Mobile body drive system and mobile body drive method, pattern formation apparatus and method, exposure apparatus and method, device manufacturing method, and decision method
38 claims: 2 independent, 36 dependent
- 1投影光学系を介して照明光で基板を露光する露光方法であって、 前記投影光学系の下方に配置されるベース上で非接触に支持され、前記基板を保持するステージを移動することと、 前記ステージに格子部とヘッドとの一方が設けられ、かつ前記格子部と前記ヘッドとの他方が前記投影光学系の下端側に配置されるように前記投影光学系を支持するフレーム部材に支持されるエンコーダシステムの、前記格子部と対向する複数の前記ヘッドによって、前記ステージの位置情報を計測することと、 前記投影光学系の光軸と垂直な所定平面内で互いに直交する第1及び第2方向の一方と異なる方向に関する前記ヘッドと前記格子部との相対運動に起因して生じる、前記一方の方向に関する前記エンコーダシステムの計測誤差を補償しつつ、前記エンコーダシステムで計測される位置情報に基づいて、前記ステージの駆動を制御することと、 前記ステージの移動中、前記エンコーダシステムで計測に用いられる前記複数のヘッドの1つを別のヘッドに切り換えることと、 を含み、 少なくとも前記基板の露光動作において、前記エンコーダシステムによって前記ステージの位置情報が計測される露光方法。
- 2請求項1に記載の露光方法において、 前記異なる方向は、前記第1及び第2方向と直交する第3方向、前記所定平面と直交する軸の回りの回転方向、及び前記所定平面と平行な軸の回りの回転方向の少なくとも1つを含む露光方法。
- 3請求項1又は2に記載の露光方法において、 前記格子部と前記ヘッドとの他方は、前記フレーム部材から支持部材を介して吊り下げ支持される露光方法。
- 4請求項1~3のいずれか一項に記載の露光方法において、 前記投影光学系から離れて前記フレーム部材に支持されるマーク検出系によって、前記基板のマークが検出され、 前記マークの検出動作において、前記エンコーダシステムによって前記ステージの位置情報が計測される露光方法。
- 5請求項1~4のいずれか一項に記載の露光方法において、 前記投影光学系の下端部を取り囲むように設けられるノズルユニットによって、前記投影光学系の下に液体で液浸領域が形成されるとともに、前記投影光学系と前記液浸領域の液体とを介して前記照明光で前記基板が露光され、 前記格子部と前記ヘッドとの他方が前記投影光学系に対して前記ノズルユニットの外側に設けられる露光方法。
- 6請求項5に記載の露光方法において、 前記フレーム部材に設けられる前記ノズルユニットによって前記液浸領域が形成される露光方法。
- 7請求項5に記載の露光方法において、 前記フレーム部材とは別のフレーム部材に設けられる前記ノズルユニットによって前記液浸領域が形成される露光方法。
- 8請求項1~7のいずれか一項に記載の露光方法において、 前記基板はその表面が前記ステージの上面とほぼ同一面となるように前記ステージに載置される露光方法。
- 9請求項1~8のいずれか一項に記載の露光方法において、 前記ステージはその上面の凹部内で前記基板の表面が前記上面とほぼ同一面となるように前記基板を保持する露光方法。
- 10請求項1~9のいずれか一項に記載の露光方法において、 前記格子部に計測ビームを照射して、前記第1及び第2方向と直交する第3方向に関する前記ステージの位置情報が計測される露光方法。
- 11請求項1~10のいずれか一項に記載の露光方法において、 前記エンコーダシステムによって、前記第1及び第2方向と、前記第1及び第2方向と直交する第3方向と、を含む6自由度方向に関する前記ステージの位置情報が計測される露光方法。
- 12請求項1~11のいずれか一項に記載の露光方法において、 前 記切換後、前記複数のヘッドのうち前記1つのヘッドを除く残りのヘッドと、前記別のヘッドと、を含む複数のヘッドによって前記ステージの位置情報が計測される露光方法。
- 13請求項12に記載の露光方法において、 前記切換前、前記格子部と対向する3つの前記ヘッドによって前記ステージの位置情報が計測されるとともに、前記切換後、前記3つのヘッドのうち前記1つのヘッドを除く2つのヘッドと、前記3つのヘッドと異なる前記別のヘッドと、を含む3つのヘッドによって前記ステージの位置情報が計測される露光方法。
- 14請求項13に記載の露光方法において、 前記エンコーダシステムの3つ又は4つの前記ヘッドが前記格子部と対向するとともに、前記格子部と対向するヘッドが、前記ステージの移動によって、前記3つのヘッドと前記4つのヘッドとの一方から他方に変更される露光方法。
- 15請求項13又は14に記載の露光方法において、 前記格子部は、それぞれ反射型格子が形成される4つのスケール部材を有し、 前記4つのスケール部材の3つ又は4つとそれぞれ対向して配置される3つ又は4つの前記ヘッドによって前記ステージの位置情報が計測される露光方法。
- 16請求項13~15のいずれか一項に記載の露光方法において、 前記1つのヘッドから前記別のヘッドへの切換は、前記切換前に用いられる前記3つのヘッドと前記別のヘッドとを含む4つのヘッドが前記格子部と対向している間に行われる露光方法。
- 17請求項1~16のいずれか一項に記載の露光方法において、 前記ステージは、前記ヘッドが設けられ、かつ前記露光動作において前記格子部の下方で移動される露光方法。
- 18請求項1~17のいずれか一項に記載の露光方法において、 前記ステージの移動では、前記ヘッドに起因して生じる前記エンコーダシステムの計測誤差、および前記所定平面に対する前記ステージの傾斜に起因して生じる前記エンコーダシステムの計測誤差の少なくとも1つも補償される露光方法。
- 19デバイス製造方法であって、 請求項1~18のいずれか一項に記載の露光方法を用いて基板を露光することと、前記露光された基板を現像することと、を含むデバイス製造方法。
- 20投影光学系を介して照明光で基板を露光する露光装置であって、 前記投影光学系を支持するフレーム部材と、 前記投影光学系の下方に配置されるベースと、 前記ベース上に配置され、前記基板を保持するステージと、 前記ベース上で非接触に支持される前記ステージを駆動する駆動系と、 前記ステージに格子部とヘッドとの一方が設けられ、かつ前記格子部と前記ヘッドとの他方が前記投影光学系の下端側に配置されるように前記フレーム部材に支持されるとともに、前記格子部と対向する複数の前記ヘッドによって、前記ステージの位置情報を計測するエンコーダシステムと、 前記投影光学系の光軸と垂直な所定平面内で互いに直交する第1及び第2方向の一方と異なる方向に関する前記ヘッドと前記格子部との相対運動に起因して生じる、前記一方の方向に関する前記エンコーダシステムの計測誤差を補償しつつ、前記エンコーダシステムで計測される位置情報に基づいて、前記駆動系を制御する制御装置と、を備え、 前記制御装置は、前記ステージの移動中、前記エンコーダシステムで計測に用いられる前記複数のヘッドの1つを別のヘッドに切り換え、 少なくとも前記基板の露光動作において、前記エンコーダシステムによって前記ステージの位置情報が計測される露光装置。
- 21請求項20に記載の露光装置において、 前記異なる方向は、前記所定平面と直交する方向、前記所定平面と直交する軸の回りの回転方向、及び前記所定平面と平行な軸の回りの回転方向の少なくとも1つを含む露光装置。
- 22請求項20又は21に記載の露光装置において、 前記格子部と前記ヘッドとの他方は、前記フレーム部材から支持部材を介して吊り下げ支持される露光装置。
- 23請求項20~22のいずれか一項に記載の露光装置において、 前記投影光学系から離れて前記フレーム部材に支持され、前記基板のマークを検出するマーク検出系を、さらに備え、 前記マークの検出動作において、前記エンコーダシステムによって前記ステージの位置情報が計測される露光装置。
- 24請求項20~23のいずれか一項に記載の露光装置において、 前記投影光学系の下端部を取り囲むように設けられるノズルユニットを有し、前記液体によって前記投影光学系の下に液浸領域を形成する局所液浸装置を、さらに備え、 前記格子部と前記ヘッドとの他方が前記投影光学系に対して前記ノズルユニットの外側に設けられ、 前記投影光学系と前記液浸領域の液体とを介して前記照明光で前記基板が露光される露光装置。
- 25請求項24に記載の露光装置において、 前記ノズルユニットは、前記フレーム部材に設けられる露光装置。
- 26請求項24に記載の露光装置において、 前記ノズルユニットは、前記フレーム部材とは別のフレーム部材に設けられる露光装置。
- 27請求項20~26のいずれか一項に記載の露光装置において、 前記基板はその表面が前記ステージの上面とほぼ同一面となるように前記ステージに載置される露光装置。
- 28請求項20~27のいずれか一項に記載の露光装置において、 前記ステージはその上面の凹部内で前記基板の表面が前記上面とほぼ同一面となるように前記基板を保持する露光装置。
- 29請求項20~28のいずれか一項に記載の露光装置において、 前記格子部に計測ビームを照射して、前記第1及び第2方向と直交する第3方向に関する前記ステージの位置情報が計測される露光装置。
- 30請求項20~29のいずれか一項に記載の露光装置において、 前記エンコーダシステムは、前記第1及び第2方向と、前記第1及び第2方向と直交する第3方向と、を含む6自由度方向に関する前記ステージの位置情報を計測する露光装置。
- 31請求項20~30のいずれか一項に記載の露光装置において、 前 記切換後、前記複数のヘッドのうち前記1つのヘッドを除く残りのヘッドと、前記別のヘッドと、を含む複数のヘッドによって前記ステージの位置情報が計測される露光装置。
- 32請求項31に記載の露光装置において、 前記切換前、前記格子部と対向する3つの前記ヘッドによって前記ステージの位置情報が計測されるとともに、前記切換後、前記3つのヘッドのうち前記1つのヘッドを除く2つのヘッドと、前記3つのヘッドと異なる前記別のヘッドと、を含む3つのヘッドによって前記ステージの位置情報が計測される露光装置。
- 33請求項32に記載の露光装置において、 前記エンコーダシステムは、3つ又は4つの前記ヘッドが前記格子部と対向するとともに、前記格子部と対向するヘッドが前記ステージの移動によって、前記3つのヘッドと前記4つのヘッドとの一方から他方に変更される露光装置。
- 34請求項32又は33に記載の露光装置において、 前記格子部は、それぞれ反射型格子が形成される4つのスケール部材を有し、 前記エンコーダシステムは、前記4つのスケール部材の3つ又は4つとそれぞれ対向して配置される3つ又は4つの前記ヘッドによって前記ステージの位置情報を計測可能である露光装置。
- 35請求項32~34のいずれか一項に記載の露光装置において、 前記1つのヘッドから前記別のヘッドへの切換は、前記切換前に用いられる前記3つのヘッドと前記別のヘッドとを含む4つのヘッドが前記格子部と対向している間に行われる露光装置。
- 36請求項20~35のいずれか一項に記載の露光装置において、 前記ステージは、前記ヘッドが設けられ、かつ前記露光動作において前記格子部の下方で移動される露光装置。
- 37請求項20~36のいずれか一項に記載の露光装置において、 前記制御装置は、前記ステージの移動中、前記ヘッドに起因して生じる前記エンコーダシステムの計測誤差、および前記所定平面に対する前記ステージの傾斜に起因して生じる前記エンコーダシステムの計測誤差の少なくとも1つも補償する露光装置。
- 38デバイス製造方法であって、 請求項20~37のいずれか一項に記載の露光装置を用いて基板を露光することと、前記露光された基板を現像することと、を含むデバイス製造方法。
Independent claims38
230 paragraphs, as filed
0001The present invention relates to an exposure method and an exposure apparatus, and a device manufacturing method, and in particular, an exposure method and an exposure apparatus for exposing an object with illumination light via a projection optical system and a liquid, and a device using the exposure method or the exposure apparatus. Regarding the manufacturing method.
0002Conventionally, in the lithography process in the manufacture of microdevices (electronic devices, etc.) such as semiconductor elements and liquid crystal display elements, step-and-repeat reduction projection exposure equipment (so-called steppers) and step-and-scan reduction projection exposure Devices (so-called scanning steppers (also called scanners)) are used relatively often.
0003In this type of exposure apparatus, in order to transfer the pattern of the reticle (or mask) to a plurality of shot regions on the wafer, the wafer stage holding the wafer is driven in the XY two-dimensional direction by, for example, a linear motor. In particular, in the case of a scanning stepper, not only the wafer stage but also the reticle stage is driven by a linear motor or the like with a predetermined stroke in the scanning direction. The position measurement of the reticle stage or the wafer stage is generally performed by using a laser interferometer having good stability of the measured value for a long period of time and high resolution.
0004However, due to the miniaturization of patterns accompanying the high integration of semiconductor elements, more accurate stage position control performance is required, and now it is caused by the temperature fluctuation of the atmosphere on the beam optical path of the laser interferometer. Short-term fluctuations in measured values occupy a large weight in the overlay budget.
0005On the other hand, there is an encoder as a device other than the laser interferometer used for stage position measurement (measurement), but since the encoder uses a scale, the mechanical long-term stability of the scale (drift of lattice pitch, It lacks fixed position drift, thermal expansion, etc.), and therefore lacks the linearity of measured values compared to laser interferometers, and has the disadvantage of being inferior in long-term stability.
0006In view of the above-mentioned drawbacks of the laser interferometer and the encoder, various devices for measuring the position of the stage by using the laser interferometer and the position detection sensor (encoder) using the diffraction grating in combination have been proposed (Patented). Refer to References 1 and 2).
0007Further, the measurement resolution of the conventional encoder is inferior to that of the interferometer, but recently, an encoder having a measurement resolution equal to or higher than that of the laser interferometer has appeared (see, for example, Patent Document 3). , The technique of combining the above-mentioned laser interferometer and the encoder has attracted attention.
0008However, when the encoder is used for measuring the position in the moving surface of the wafer stage of the exposure apparatus, for example, even if one encoder head is used to measure the position of the stage provided with the scale (grating). , When a relative motion other than the desired direction (measurement direction) occurs between the head and the scale, a change is detected in the measured value (count) in many cases, and a measurement error occurs. In addition to this, when actually applying an encoder to the wafer stage of an exposure apparatus, it is necessary to use a plurality of encoder heads for one scale, for example, tilting between encoder heads (tilt of the optical axis). There is also an inconvenience that an error occurs in the count value of the encoder due to the difference between the two.
<p num="0009"><patcit num="1"><text>JP-A-2002-151405</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2004-101362</text></patcit><patcit num="3"><text>Japanese Patent Application Laid-Open No. 2005-308592</text></patcit></p>
<p num="0010"> Inventors and others have conducted various simulations in order to know the effect of the relative displacement of the head and scale in the non-measurement direction on the encoder measurement value when measuring the position of the stage of the exposure apparatus with a reflective optical encoder. Was done. As a result, it was found that the count value of the encoder is sensitive to the posture change in the pitching direction and the yawing direction of the stage, and may also depend on the position change in the direction orthogonal to the moving surface of the stage.</p><p num="0011"> According to the first aspect of the present invention, there is an exposure method in which a substrate is exposed with illumination light via a projection optical system, which is non-contactly supported on a base arranged below the projection optical system. The stage for holding the substrate is moved, and the stage is provided with one of a lattice portion and a head, and the other of the lattice portion and the head is arranged on the lower end side of the projection optical system. The position information of the stage is measured by the plurality of heads of the encoder system supported by the frame member supporting the projection optical system and facing the lattice portion, and the predetermined position perpendicular to the optical axis of the projection optical system is measured. While compensating for the measurement error of the encoder system with respect to the one direction caused by the relative motion between the head and the lattice portion in a direction different from one of the first and second directions orthogonal to each other in the plane. Controlling the drive of the stage based on the position information measured by the encoder system,<u style="single">Switching one of the plurality of heads used for measurement in the encoder system to another head while the stage is moving,</u>Provided is an exposure method in which the position information of the stage is measured by the encoder system at least in the exposure operation of the substrate.</p><p num="0012"> According to this, it is possible to control the movement of the stage with high accuracy, at least in the exposure operation of the substrate.</p><p num="0013"> According to the second aspect of the present invention, there is a device manufacturing method including the exposure of a substrate using the exposure method according to the first aspect and the development of the exposed substrate. The method is provided.</p><p num="0014"> According to the third aspect of the present invention, it is an exposure apparatus that exposes a substrate with illumination light via a projection optical system, and is arranged below a frame member that supports the projection optical system and the projection optical system. A base, a stage arranged on the base and holding the substrate, a drive system for driving the stage non-contactly supported on the base, and one of a lattice portion and a head provided on the stage. The other of the lattice portion and the head is supported by the frame member so as to be arranged on the lower end side of the projection optical system, and the stage is supported by the plurality of heads facing the lattice portion. Caused by the relative motion of the head and the lattice portion in a direction different from one of the first and second directions orthogonal to each other in a predetermined plane perpendicular to the optical axis of the projection optical system and the encoder system for measuring position information. A control device that controls the drive system based on the position information measured by the encoder system while compensating for the measurement error of the encoder system with respect to the one direction.<u style="single">The control device switches one of the plurality of heads used for measurement in the encoder system to another head while the stage is moving.</u>An exposure apparatus is provided in which the position information of the stage is measured by the encoder system at least in the exposure operation of the substrate.</p><p num="0015"> According to this, it is possible to control the movement of the stage with high accuracy, at least in the exposure operation of the substrate.</p><p num="0016"> According to a fourth aspect of the present invention, there is a device manufacturing method including device manufacturing including exposing a substrate using the exposure apparatus according to the third aspect and developing the exposed substrate. The method is provided.</p>
0017<figref num="1">It is a figure which shows schematic structure of the exposure apparatus which concerns on one Embodiment.</figref><figref num="2">It is a top view which shows the stage apparatus of FIG.</figref><figref num="3">It is a top view which shows the arrangement of various measuring devices (encoder, alignment system, multi-point AF system, Z sensor, etc.) included in the exposure apparatus of FIG.</figref><figref num="4">FIG. 4A is a plan view showing the wafer stage, and FIG. 4B is a schematic side view showing a partially cross-sectional view of the wafer stage WST.</figref><figref num="5">FIG. 5 (A) is a plan view showing the measurement stage, and FIG. 5 (B) is a schematic side view showing a partial cross section showing the measurement stage.</figref><figref num="6">It is a block diagram which shows the main structure of the control system of the exposure apparatus which concerns on one Embodiment.</figref><figref num="7">7 (A) and 7 (B) are for explaining the position measurement in the XY plane of the wafer table by a plurality of encoders including a plurality of heads arranged in an array and the transfer of the measured values between the heads. It is a figure of.</figref><figref num="8">FIG. 8 (A) is a diagram showing an example of the encoder configuration, and FIG. 8 (B) is a diagram for explaining the mechanism of occurrence of this measurement error with respect to the reflection type diffraction grating of the beam in the encoder head. It is a figure for demonstrating the relationship between incident light and diffracted light.</figref><figref num="9">FIG. 9 (A) shows a case where the count value does not change even when a relative motion in the non-measurement direction occurs between the encoder head and the scale, and FIG. 9 (B) shows the encoder head. It is a figure which shows an example of the case where a count value changes when a relative motion in a non-measurement direction occurs between a scale and a scale.</figref><figref num="10">FIGS. 10 (A) to 10 (D) explain the case where the encoder count value changes and the case where the count value does not change when a relative motion in the non-measurement direction occurs between the head and the scale. It is a figure for doing.</figref><figref num="11">11 (A) and 11 (B) are operations for acquiring correction information for correcting the measurement error of the encoder (first encoder) due to the relative movement of the head and the scale in the non-measurement direction. It is a figure for demonstrating.</figref><figref num="12">It is a graph which shows the measurement error of the encoder with respect to the change of Z position at the pitching amount θx = α.</figref><figref num="13">It is a figure for demonstrating the operation for acquiring the correction information which corrects the measurement error of another encoder (the second encoder) caused by the relative movement of a head and a scale in a non-measurement direction.</figref><figref num="14">It is a figure which shows the state of the wafer stage and the measurement stage in the state which the step-and-scan method exposure is performed on the wafer on the wafer stage.</figref><figref num="15">It is a figure which shows the state of both stages immediately after the transition from the state where the wafer stage and the measurement stage are separated to the state where both stages are in contact after the end of exposure.</figref><figref num="16">The figure shows the state of both stages when the measurement stage moves in the -Y direction and the wafer stage moves toward the unloading position while maintaining the positional relationship between the wafer table and the measurement table in the Y-axis direction. is there.</figref><figref num="17">It is a figure which shows the state of the wafer stage and the measurement stage when the measurement stage reaches the position which performs Sec-BCHK (interval).</figref><figref num="18">It is a figure which shows the state of the wafer stage and the measurement stage when the wafer stage moves from an unload position to a loading position in parallel with performing Sec-BCHK (interval).</figref><figref num="19">It is a figure which shows the state of the wafer stage and the measurement stage when the measurement stage moves to the optimum scrum standby position, and the wafer is loaded on the wafer table.</figref><figref num="20">It is a figure which shows the state of both stages when the wafer stage moves to the position which performs the processing of the first half of Pri-BCHK while the measurement stage is waiting at the optimum scrum standby position.</figref><figref num="21">Alignment system AL1, AL2<sub>2</sub>, AL2<sub>3</sub>It is a figure which shows the state of the wafer stage and the measurement stage at the time of simultaneously detecting the alignment mark attached to three first alignment shot regions by using.</figref><figref num="22">It is a figure which shows the state of the wafer stage and the measurement stage at the time of processing of the first half of focus calibration.</figref><figref num="23">Alignment system AL1, AL2<sub>1</sub>~ AL2<sub>4</sub>Is a diagram showing the state of the wafer stage and the measurement stage when the alignment marks attached to the five second alignment shot regions are simultaneously detected using.</figref><figref num="24">It is a figure which shows the state of the wafer stage and the measurement stage when at least one of the processing of the latter half of Pri-BCHK and the processing of the latter half of focus calibration is performed.</figref><figref num="25">Alignment system AL1, AL2<sub>1</sub>~ AL2<sub>4</sub>It is a figure which shows the state of the wafer stage and the measurement stage at the time of simultaneous detection of the alignment mark attached to 5 third alignment shot regions by using.</figref><figref num="26">Alignment system AL1, AL2<sub>2</sub>, AL2<sub>3</sub>It is a figure which shows the state of the wafer stage and the measurement stage at the time of simultaneously detecting the alignment mark attached to three force alignment shot regions by using.</figref><figref num="27">It is a figure which shows the state of the wafer stage and the measurement stage when the focus mapping is completed.</figref><figref num="28">It is a flowchart for demonstrating embodiment of the device manufacturing method.</figref><figref num="29">It is a flowchart which shows the specific example of step 204 of FIG.</figref>
0018Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 27.
0019FIG. 1 schematically shows the configuration of the exposure apparatus 100 according to the embodiment. The exposure apparatus 100 is a step-and-scan scanning exposure apparatus, that is, a so-called scanner. As will be described later, in the present embodiment, the projection optical system PL is provided, and in the following, the direction parallel to the optical axis AX of the projection optical system PL is the Z-axis direction, and the reticle is defined in a plane orthogonal to the Z-axis direction. The direction in which the wafer is relatively scanned is the Y-axis direction, the direction orthogonal to the Z-axis and the Y-axis is the X-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are θx, θy, and θy, respectively. And the θz direction will be described.
0020The exposure apparatus 100 includes a reticle stage RST and a reticle R that hold a reticle R illuminated by an illumination system 10 and an illumination illumination light (hereinafter, referred to as "illumination light" or "exposure light") IL from the illumination system 10. It includes a projection unit PU including a projection optical system PL that projects the illumination light IL emitted from the wafer W, a stage device 50 having a wafer stage WST and a measurement stage MST, and a control system thereof. Wafer W is placed on the wafer stage WST.
0021The illumination system 10 is an illuminance uniforming optical system including a light source, an optical integrator, and the like, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-313250 (corresponding US Patent Application Publication No. 2003/0025890). And an illumination optical system having reticle blinds and the like (both not shown). In this illumination system 10, a slit-shaped illumination region extending in the X-axis direction on the reticle R defined by the reticle blind (masking system) is illuminated with an illumination light (exposure light) IL with substantially uniform illuminance. Here, as the illumination light IL, ArF excimer laser light (wavelength 193 nm) is used as an example. Further, as the optical integrator, for example, a fly-eye lens, a rod integrator (internal reflection type integrator), a diffractive optical element, or the like can be used.
0022On the reticle stage RST, a reticle R on which a circuit pattern or the like is formed on the pattern surface (lower surface in FIG. 1) is fixed by, for example, vacuum suction. The reticle stage RST can be slightly driven in the XY plane by a reticle stage drive system 11 (not shown in FIG. 1, see FIG. 6) including, for example, a linear motor, and can be driven in a predetermined scanning direction (inside the paper surface in FIG. 1). It can be driven at the scanning speed specified in the left-right direction (Y-axis direction).
0023Positional information (including rotation information in the θz direction) of the reticle stage RST in the moving plane is transmitted by the reticle laser interferometer (hereinafter referred to as "reticle interferometer") 116 to the moving mirror 15 (actually, in the Y-axis direction). It is always detected with a resolution of, for example, about 0.5 to 1 nm through a Y moving mirror having orthogonal reflecting surfaces and an X moving mirror having reflecting surfaces orthogonal to the X-axis direction). The measured value of the reticle interferometer 116 is sent to the main controller 20 (not shown in FIG. 1, see FIG. 6). The main controller 20 calculates the positions of the reticle stage RST in the X-axis direction, the Y-axis direction, and the θz direction based on the measured values of the reticle interferometer 116, and controls the reticle stage drive system 11 based on the calculation results. By doing so, the position (and speed) of the reticle stage RST is controlled. Instead of the moving mirror 15, the end surface of the reticle stage RST may be mirror-processed to form a reflecting surface (corresponding to the reflecting surface of the moving mirror 15). Further, the reticle interferometer 116 may be capable of measuring the position information of the reticle stage RST in at least one of the Z-axis, θx and θy directions.
0024The projection unit PU is located below the reticle stage RST in FIG. The projection unit PU includes a lens barrel 40 and a projection optical system PL having a plurality of optical elements held in the lens barrel 40 in a predetermined positional relationship. As the projection optical system PL, for example, a refractive optical system composed of a plurality of lenses (lens elements) arranged along the optical axis AX parallel to the Z-axis direction is used. The projection optical system PL is, for example, telecentric on both sides and has a predetermined projection magnification (for example, 1/4 times, 1/5 times, 1/8 times, etc.). Therefore, when the illumination region IAR is illuminated by the illumination light IL from the illumination system 10, the illumination passes through the reticle R in which the first surface (object surface) of the projection optical system PL and the pattern surface are arranged so as to be substantially aligned with each other. By optical IL, a reduced image of the circuit pattern of the reticle (a reduced image of a part of the circuit pattern) in the illumination area IAR via the projection optical system PL (projection unit PU) and liquid Lq (see Fig. 1) is displayed. It is formed in a region (exposure region) IA that is arranged on the second surface (image plane) side and is conjugate to the illumination region IAR on the wafer W on which a resist (photosensitive agent) is coated on the surface. Then, by synchronously driving the reticle stage RST and the wafer stage WST, the reticle is relatively moved in the scanning direction (Y-axis direction) with respect to the illumination region IAR (illumination light IL), and with respect to the exposure region (illumination light IL). By moving the wafer W relative to the scanning direction (Y-axis direction), scanning exposure of one shot region (partition region) on the wafer W is performed, and the reticle pattern is transferred to the shot region. That is, in the present embodiment, a pattern is generated on the wafer W by the illumination system 10, the reticle, and the projection optical system PL, and the pattern is generated on the wafer W by exposure of the sensitive layer (resist layer) on the wafer W by the illumination light IL. It is formed. Although not shown, the projection unit PU is mounted on a lens barrel surface plate supported by three columns via an anti-vibration mechanism, as disclosed in, for example, International Publication No. 2006/038952. , A mainframe member (not shown) located above the projection unit PU,
0025Further, in the exposure apparatus 100 of the present embodiment, since the exposure is performed by applying the immersion method, the optical element on the most image plane side (wafer W side) constituting the projection optical system PL, here the lens (hereinafter, "tip"). A nozzle unit 32 that forms a part of the local immersion device 8 is provided so as to surround the lower end portion of the lens barrel 40 that holds the lens) 191. In the present embodiment, as shown in FIG. 1, the lower end surface of the nozzle unit 32 is set to be substantially flush with the lower end surface of the tip lens 191. Further, the nozzle unit 32 is connected to the liquid Lq supply port and the recovery port, the lower surface on which the wafer W is arranged facing each other and the recovery port is provided, and the liquid supply pipe 31A and the liquid recovery pipe 31B, respectively. It is provided with a flow path and a recovery flow path. As shown in FIG. 3, the liquid supply pipe 31A and the liquid recovery pipe 31B are tilted by 45 ° with respect to the X-axis direction and the Y-axis direction in a plan view (viewed from above), and the light of the projection optical system PL. The arrangement is symmetrical with respect to the straight line LV in the Y-axis direction passing through the axis AX.
0026The liquid supply pipe 31A is connected to the other end of a supply pipe (not shown, see FIG. 6) whose end is connected to the liquid supply device 5 (not shown in FIG. 1, see FIG. 6). The other end of a recovery pipe (not shown, see FIG. 6), one end of which is connected to the liquid recovery device 6 (not shown in FIG. 1), is connected.
0027The liquid supply device 5 includes a liquid tank, a pressurizing pump, a temperature control device, a valve for controlling the supply / stop of the liquid to the liquid supply pipe 31A, and the like. As the valve, for example, it is desirable to use a flow rate control valve so that not only the supply / stop of the liquid but also the flow rate can be adjusted. The temperature control device adjusts the temperature of the liquid in the liquid tank to a temperature similar to the temperature in the chamber (not shown) in which the exposure device is housed. It is not necessary for the exposure device 100 to include all of the tank, pressure pump, temperature control device, valve, etc. for supplying liquid, and at least a part of the tank, pressure pump, temperature control device, valve, etc. It can be replaced by equipment.
0028The liquid recovery device 6 includes a liquid tank, a suction pump, a valve for controlling the recovery / stop of the liquid via the liquid recovery pipe 31B, and the like. As the valve, it is desirable to use a flow rate control valve corresponding to the valve of the liquid supply device 5. The tank, suction pump, valve, etc. for collecting liquid do not have to be all equipped with the exposure device 100, and at least a part of them should be replaced with equipment such as a factory where the exposure device 100 is installed. You can also.
0029In the present embodiment, as the above liquid, pure water through which ArF excimer laser light (light having a wavelength of 193 nm) is transmitted (hereinafter, simply referred to as "water" unless otherwise required) is used. Pure water has the advantage that it can be easily obtained in large quantities at semiconductor manufacturing factories and the like, and that there is no adverse effect on the photoresist, optical lens, etc. on the wafer.
0030The refractive index n of water with respect to ArF excimer laser light is approximately 1.44. In this water, the wavelength of the illumination light IL is shortened to 193 nm × 1 / n = about 134 nm.
0031The liquid supply device 5 and the liquid recovery device 6 each include a controller, and each controller is controlled by the main controller 20 (see FIG. 6). The controller of the liquid supply device 5 opens the valve connected to the liquid supply pipe 31A at a predetermined opening degree in response to the instruction from the main control device 20, and opens the tip through the liquid supply pipe 31A, the supply flow path, and the supply port. Water Lq (see FIG. 1) is supplied between the lens 191 and the wafer W. At this time, the controller of the liquid recovery device 6 opens the valve connected to the liquid recovery pipe 31B at a predetermined opening degree in response to the instruction from the main control device 20, and opens the recovery port, the recovery flow path, and the liquid recovery pipe. Water Lq is recovered inside the liquid recovery device 6 (liquid tank) from between the tip lens 191 and the wafer W via 31B. At this time, the main controller 20 is a controller of the liquid supply device 5 so that the amount of water Lq supplied between the tip lens 191 and the wafer W is always equal to the amount of water Lq recovered. Give a command to the controller of the liquid recovery device 6. Therefore, a certain amount of water Lq is held between the tip lens 191 and the wafer W (see FIG. 1). In this case, the water Lq held between the tip lens 191 and the wafer W is constantly replaced.
0032As is clear from the above description, in the present embodiment, the local immersion device 8 is configured to include the nozzle unit 32, the liquid supply device 5, the liquid recovery device 6, the liquid supply pipe 31A, the liquid recovery pipe 31B, and the like. There is. In the local immersion device 8, the nozzle unit 32 fills the space between the tip lens 191 and the wafer W with the liquid Lq, and the local immersion space including the optical path space of the illumination light IL (corresponding to the immersion region 14). To form. Therefore, the nozzle unit 32 is a immersion space forming member or a containment member (or confinement). Also called member). A part of the local immersion device 8, for example, at least the nozzle unit 32, may be suspended and supported by a main frame (including the lens barrel surface plate described above) holding the projection unit PU, and the main frame is defined as a main frame. It may be provided on another frame member. Alternatively, when the projection unit PU is suspended and supported as described above, the nozzle unit 32 may be suspended and supported integrally with the projection unit PU, but in the present embodiment, the projection unit PU is suspended and supported independently of the projection unit PU. A nozzle unit 32 is provided in the measurement frame to be measured. In this case, the projection unit PU does not have to be suspended and supported.
0033Even when the measurement stage MST is located below the projection unit PU, it is possible to fill water between the measurement table and the tip lens 191 which will be described later in the same manner as described above.
0034In the above description, as an example, one liquid supply pipe (nozzle) and one liquid recovery pipe (nozzle) are provided, but the present invention is not limited to this, and the relationship with surrounding members is taken into consideration. However, if the arrangement is possible, for example, as disclosed in International Publication No. 99/49504, a configuration having a large number of nozzles may be adopted. Further, the lower surface of the nozzle unit 32 is arranged closer to the image plane (that is, the wafer) of the projection optical system PL than the ejection surface of the tip lens 191, or in addition to the optical path on the image plane side of the tip lens 191. A configuration may be adopted in which the optical path on the object surface side of 191 is also filled with liquid. In short, any configuration may be used as long as the liquid can be supplied between at least the lowermost optical member (tip lens) 191 constituting the projection optical system PL and the wafer W. For example, the immersion mechanism disclosed in International Publication No. 2004/053955 or the immersion mechanism disclosed in European Patent Application Publication No. 1420298 can also be applied to the exposure apparatus of the present embodiment. ..
0035Returning to FIG. 1, the stage apparatus 50 includes interference including a wafer stage WST and a measurement stage MST arranged above the base board 12, and Y interferometers 16, 18 for measuring the position information of these stages WST and MST. The meter system 118 (see Fig. 6), the encoder system described later used to measure the position information of the wafer stage WST during exposure, and the stage drive system 124 that drives the stages WST and MST (see Fig. 6). And so on.
0036Non-contact bearings (not shown), for example, vacuum preload type pneumatic static pressure bearings (hereinafter referred to as "air pads") are provided at a plurality of places on the bottom surface of each of the wafer stage WST and the measurement stage MST. Due to the static pressure of the pressurized air ejected from these air pads toward the upper surface of the base plate 12, the wafer stage WST and the measurement stage MST are supported above the base plate 12 in a non-contact manner through a clearance of about several μm. ing. Further, the stages WST and MST are independently controlled by the stage drive system 124 in the Y-axis direction (left-right direction in the paper surface in FIG. 1) and the X-axis direction (orthogonal direction in the paper surface in FIG. 1) in a predetermined plane (XY plane). It can be driven in two dimensions.
0037More specifically, on the floor surface, as shown in the plan view of FIG. 2, a pair of Y extending in the Y-axis direction on one side and the other side in the X-axis direction with the base plate 12 sandwiched between them. Shaft stators 86 and 87 are arranged respectively. The Y-axis stators 86 and 87 are composed of, for example, a magnetic pole unit containing a permanent magnet group consisting of a plurality of pairs of N-pole magnets and S-pole magnets arranged at predetermined intervals and alternately along the Y-axis direction. There is. The Y-axis stators 86 and 87 are provided with two Y-axis stators 82, 84 and 83, 85, respectively, in a non-contact engagement state. That is, a total of four Y-axis stators 82, 84, 83, and 85 are inserted into the internal space of the U-shaped Y-axis stator 86 or 87 with an XZ cross section, and the corresponding Y-axis stators 82, 84, 83, and 85 are inserted. It is non-contactly supported by an air pad (not shown) with respect to 86 or 87, for example, through a clearance of about several μm. Each of the Y-axis movers 82, 84, 83, and 85 is composed of armature units incorporating armature coils arranged at predetermined intervals along the Y-axis direction, for example. That is, in the present embodiment, the moving coil type Y-axis linear motor is configured by the Y-axis movers 82 and 84 including the armature unit and the Y-axis stator 86 including the magnetic pole unit, respectively. Similarly, the Y-axis movers 83 and 85 and the Y-axis stator 87 constitute a moving coil type Y-axis linear motor, respectively. In the following, each of the above four Y-axis linear motors will be used with the same reference numerals as the movers 82, 84, 83, and 85, respectively, and the Y-axis linear motor 82, Y-axis linear motor 84, and Y-axis will be used as appropriate. It shall be referred to as a linear motor 83 and a Y-axis linear motor 85.
0038Of the above four Y-axis linear motors, the movers 82 and 83 of the two Y-axis linear motors 82 and 83 are fixed to one end and the other end of the X-axis stator 80 extending in the X-axis direction in the longitudinal direction, respectively. There is. Further, the movers 84 and 85 of the remaining two Y-axis linear motors 84 and 85 are fixed to one end and the other end of the X-axis stator 81 extending in the X-axis direction. Therefore, the X-axis stators 80 and 81 are driven along the Y-axis by each pair of Y-axis linear motors 82, 83, 84, 85, respectively.
0039Each of the X-axis stators 80 and 81 is composed of armature units containing armature coils arranged at predetermined intervals along the X-axis direction, for example.
0040On the other hand, the X-axis stator 81 is provided in an inserted state in an opening (not shown in FIG. 2, see FIG. 1) formed in the stage body 91 (not shown in FIG. 2, see FIG. 1) which constitutes a part of the wafer stage WST. Inside the opening of the stage body 91, for example, a magnetic pole unit having a permanent magnet group composed of a plurality of pairs of N-pole magnets and S-pole magnets arranged at predetermined intervals and alternately along the X-axis direction is provided. Has been done. The magnetic pole unit and the X-axis stator 81 constitute a moving magnet type X-axis linear motor that drives the stage body 91 in the X-axis direction. Similarly, the other X-axis stator 80 is provided in an inserted state in the opening formed in the stage body 92 constituting the measurement stage MST. Inside the opening of the stage body 92, a magnetic pole unit similar to that on the wafer stage WST side (stage body 91 side) is provided. The magnetic pole unit and the X-axis stator 80 constitute a moving magnet type X-axis linear motor that drives the measurement stage MST in the X-axis direction.
0041In the present embodiment, each of the linear motors constituting the stage drive system 124 is controlled by the main control device 20 shown in FIG. The linear motor is not limited to either the moving magnet type or the moving coil type, and can be appropriately selected as needed.
0042By slightly different thrusts generated by the pair of Y-axis linear motors 84 and 85, it is possible to control the yawing amount (rotation amount in the θz direction) of the wafer stage WST. Further, the yawing amount of the measurement stage MST can be controlled by slightly differentizing the thrusts generated by the pair of Y-axis linear motors 82 and 83, respectively.
0043The wafer stage WST includes the above-mentioned stage main body 91 and a wafer table WTB mounted on the stage main body 91. The wafer table WTB and the stage body 91 are subjected to a Z-leveling mechanism (including, for example, a voice coil motor) (not shown) in the Z-axis direction, the θx direction, and the θy direction with respect to the base plate 12 and the X-axis stator 81. It is driven relatively minutely. That is, the wafer table WTB can be finely moved and tilted (tilted) in the Z-axis direction with respect to the XY plane (or the image plane of the projection optical system PL). In FIG. 6, each of the above linear motors, the Z leveling mechanism, and the drive system of the measurement stage MST are included and shown as the stage drive system 124. Further, the wafer table WTB may be configured so that it can be finely moved in at least one of the X-axis, the Y-axis, and the θz direction.
0044A wafer holder (not shown) for holding the wafer W by vacuum suction or the like is provided on the wafer table WTB. The wafer holder may be formed integrally with the wafer table WTB, but in the present embodiment, the wafer holder and the wafer table WTB are separately configured, and the wafer holder is fixed in the recess of the wafer table WTB by, for example, vacuum suction. Further, the upper surface of the wafer table WTB has a surface (liquid-repellent surface) that has been treated to be liquid-repellent with respect to liquid Lq, which is substantially flush with the surface of the wafer placed on the wafer holder, and has an outer shape (liquid-repellent surface). A plate (liquid repellent plate) 28 having a rectangular contour (outline) and a circular opening slightly larger than the wafer holder (wafer mounting area) is provided at the center thereof. Plate 28 is a material with a low coefficient of thermal expansion, such as glass or ceramics (Shot's Zerodur (trade name), Al.<sub>2</sub>O<sub>3</sub>Alternatively, it is made of TiC, etc.), and on its surface, a liquid-repellent film is made of, for example, a fluororesin material, a fluororesin material such as polytetrafluoroethylene (Teflon (registered trademark)), an acrylic resin material, or a silicon resin material. Is formed. Further, the plate 28 has a first liquid repellent region 28a having a rectangular outer shape (contour) surrounding a circular opening and a first liquid repellent region 28a, as shown in the plan view of the wafer table WTB (wafer stage WST) of FIG. 4 (A). It has a rectangular frame-shaped (annular) second liquid-repellent region 28b arranged around the liquid-repellent region 28a. The first liquid-repellent region 28a is formed, for example, at least a part of the immersion region 14 protruding from the surface of the wafer during the exposure operation, and the second liquid-repellent region 28b is a scale (lattice portion) for an encoder system described later. Is formed. At least a part of the surface of the plate 28 does not have to be flush with the surface of the wafer, that is, it may have a different height. Further, the plate 28 may be a single plate, but in the present embodiment, a plurality of plates, for example, first and second liquid repellent plates corresponding to the first and second liquid repellent regions 28a and 28b, respectively, are combined and configured. .. In this embodiment, since pure water is used as the liquid Lq as described above, the first and second water repellent regions 28a and 28b are also referred to as the first and second water repellent plates 28a and 28b, respectively.
0045In this case, the first water-repellent plate 28a on the inner side is irradiated with the exposure light IL, whereas the second water-repellent plate 28b on the outer side is hardly irradiated with the exposure light IL. In consideration of this, in the present embodiment, the surface of the first water-repellent plate 28a is provided with a water-repellent coating having sufficient resistance to exposure light IL (in this case, light in the vacuum ultraviolet region). A water-repellent region is formed, and a second water-repellent region is formed on the surface of the second water-repellent plate 28b with a water-repellent coating that is inferior in resistance to exposure light IL as compared with the first water-repellent region. ing. In general, it is difficult to apply a water-repellent coating that has sufficient resistance to exposure light IL (in this case, light in the vacuum ultraviolet region) on the glass plate. Therefore, in this way, the first water-repellent plate 28a and the second water-repellent plate around it are water-repellent. It is effective to separate it into two parts with the plate 28b. Not limited to this, two types of water-repellent coatings having different resistance to exposure light IL may be applied to the upper surface of the same plate to form a first water-repellent region and a second water-repellent region. Further, the type of the water-repellent coat may be the same in the first and second water-repellent regions. For example, only one water repellent region may be formed on the same plate.
0046Further, as is clear from FIG. 4 (A), a rectangular notch is formed at the + Y side end of the first water repellent plate 28a at the center in the X-axis direction, and this notch and the first 2 The measuring plate 30 is embedded inside the rectangular space (inside the notch) surrounded by the water repellent plate 28b. A reference mark FM is formed in the center of the measurement plate 30 in the longitudinal direction (on the center line LL of the wafer table WTB), and the reference mark FM is formed on one side and the other side of the reference mark FM in the X-axis direction. A pair of spatial image measurement slit patterns SL are formed in a symmetrical arrangement with respect to the center. As an example of each spatial image measurement slit pattern SL, an L-shaped slit pattern having sides along the Y-axis direction and the X-axis direction can be used.
0047Then, as shown in FIG. 4B, an optical system including an objective lens, a mirror, a relay lens, etc. is housed in the wafer stage WST portion below each spatial image measurement slit pattern SL. The character-shaped housing 36 is attached in a partially embedded state so as to penetrate a part of the inside of the stage main body 91 from the wafer table WTB. Although not shown, the housing 36 is provided with a pair corresponding to the pair of spatial image measurement slit patterns SL.
0048The optical system inside the housing 36 guides the illumination light IL transmitted from above to below the spatial image measurement slit pattern SL along an L-shaped path and emits it in the -Y direction. In the following, for convenience, the optical system inside the housing 36 will be referred to as the light transmitting system 36 using the same reference numerals as those of the housing 36.
0049Further, on the upper surface of the second water repellent plate 28b, a large number of grid lines are directly formed along each of the four sides at a predetermined pitch. To further elaborate on this, the area on one side and the other side (both left and right sides in FIG. 4A) of the second water repellent plate 28b in the X-axis direction is Y scale 39Y.<sub>1</sub>, 39Y<sub>2</sub>Are formed respectively. Y scale 39Y<sub>1</sub>, 39Y<sub>2</sub>Is a reflection type lattice having the Y-axis direction as the periodic direction, for example, in which grid lines 38 having the X-axis direction as the longitudinal direction are formed at a predetermined pitch along a direction parallel to the Y-axis (Y-axis direction). For example, it is composed of a diffraction grid).
0050Similarly, in the area of the second water repellent plate 28b on one side in the Y-axis direction and the other side (both upper and lower sides in FIG. 4 (A)), the X scale 39X<sub>1</sub>, 39X<sub>2</sub>Are formed respectively. X scale 39X<sub>1</sub>, 39X<sub>2</sub>For example, a reflection type grid having the X-axis direction as the periodic direction, in which grid lines 37 having the Y-axis direction as the longitudinal direction are formed at a predetermined pitch along a direction parallel to the X-axis (X-axis direction). For example, it is composed of a diffraction grid). As each of the scales, one in which a reflective diffraction grating RG (FIG. 8 (A)) is created on the surface of the second water-repellent plate 28b by, for example, a hologram or the like is used. In this case, each scale is engraved with a grid consisting of narrow slits, grooves, etc. at predetermined intervals (pitch) as a scale. The type of diffraction grating used for each scale is not limited, and it may be not only a mechanically formed groove or the like, but also, for example, one created by baking interference fringes on a photosensitive resin. .. However, each scale is created by engraving the scale of the diffraction grating on, for example, a thin plate of glass at a pitch between 138 nm and 4 μm, for example, a pitch of 1 μm. These scales are covered with the above-mentioned liquid repellent film (water repellent film). In FIG. 4A, for convenience of illustration, the grid pitch is shown to be much wider than the actual pitch. The same applies to other figures.
0051As described above, in the present embodiment, since the second water-repellent plate 28b itself constitutes the scale, a glass plate having a low coefficient of thermal expansion is used as the second water-repellent plate 28b. However, the present invention is not limited to this, and the upper surface of the wafer table WTB is formed by using, for example, a leaf spring (or vacuum suction) or the like to prevent local expansion and contraction of a scale member made of a glass plate having a low thermal expansion rate in which a lattice is formed. In this case, a water-repellent plate having the same water-repellent coating on the entire surface may be used instead of the plate 28. Alternatively, the wafer table WTB may be formed of a material having a low coefficient of thermal expansion, and in such a case, the pair of Y scales and the X scale may be formed directly on the upper surface of the wafer table WTB.
0052The -Y end face and the -X end face of the wafer table WTB are mirror-finished to form the reflection surface 17a and the reflection surface 17b shown in FIG. 2, respectively. The Y interferometer 16 and the X interferometers 126, 127, 128 (in FIG. 1, the X interferometers 126 to 128 are not shown, see FIG. 2), which form a part of the interferometer system 118 (see FIG. 6), are these. By projecting an interferometer beam (length measuring beam) on each of the reflecting surfaces 17a and 17b and receiving the reflected light, a fixed mirror is placed at the reference position of each reflecting surface (generally, a fixed mirror is placed on the side of the projection unit PU. , That is, the displacement from the reference plane), that is, the position information of the wafer stage WST in the XY plane is measured, and the measured position information is supplied to the main control device 20. In the present embodiment, as described later, as each of the interferometers, a multi-axis interferometer having a plurality of length measuring axes is used, except for a part.
0053On the other hand, on the side surface of the stage body 91 on the -Y side, as shown in FIGS. 1 and 4 (B), a moving mirror 41 having the X-axis direction as the longitudinal direction is provided via a kinematic support mechanism (not shown). Is attached.
0054A pair of Z interferometers 43A and 43B forming a part of the interferometer system 118 (see FIG. 6) that irradiate the moving mirror 41 with a length measuring beam facing the moving mirror 41 are provided (FIG. 6). 1 and Figure 2). More specifically, the moving mirror 41 has a length in the X-axis direction of at least the Z interferometer 43A, which is longer than that of the reflecting surface 17a of the wafer table WTB, as can be seen by combining FIGS. 2 and 4 (B). It is designed to be longer by the interval of 43B. Further, the moving mirror 41 is made of a member having a hexagonal cross-sectional shape such that a rectangle and an isosceles trapezium are integrated. The surface of the moving mirror 41 on the -Y side is mirror-finished to form three reflecting surfaces 41b, 41a, and 41c.
0055The reflecting surface 41a constitutes the end surface on the -Y side of the moving mirror 41, and extends parallel to the XZ plane and in the X-axis direction. The reflective surface 41b constitutes a surface adjacent to the + Z side of the reflective surface 41a, and extends in the X-axis direction parallel to the surface inclined in the clockwise direction in FIG. 4 (B) by a predetermined angle with respect to the XZ plane. ing. The reflecting surface 41c constitutes a surface adjacent to the -Z side of the reflecting surface 41a, and is provided symmetrically with the reflecting surface 41b with the reflecting surface 41a interposed therebetween.
0056As can be seen by combining FIGS. 1 and 2, the Z interferometers 43A and 43B are approximately the same distance on one side and the other side of the Y interferometer 16 in the X-axis direction, and are slightly lower than the Y interferometer 16. They are placed in their respective positions.
0057As shown in FIG. 1, the length measuring beam B1 along the Y-axis direction is projected toward the reflection surface 41b from each of the Z interferometers 43A and 43B, and the length measurement beam B2 along the Y-axis direction is projected from the reflection surface. It is designed to be projected toward 41c (see Fig. 4 (B)). In the present embodiment, the fixed mirror 47A having a reflecting surface orthogonal to the length measuring beam B1 reflected by the reflecting surface 41b and the fixed mirror 47B having a reflecting surface orthogonal to the length measuring beam B2 reflected by the reflecting surface 41c are , It is extended in the X-axis direction at a position separated from the moving mirror 41 in the -Y direction by a predetermined distance without interfering with the length measuring beams B1 and B2.
0058The fixed mirrors 47A and 47B are supported, for example, by the same support (not shown) provided on a frame (not shown) that supports the projection unit PU. The fixed mirrors 47A and 47B may be provided in the above-mentioned measurement frame or the like. Further, in the present embodiment, the moving mirror 41 having three reflecting surfaces 41b, 41a and 41c and the fixed mirrors 47A and 47B are provided, but the present invention is not limited to this, and for example, a moving mirror having a 45-degree slope is provided. May be provided on the side surface of the stage main body 91, and a fixed mirror may be arranged above the wafer stage WST. In this case, the fixed mirror may be provided on the above-mentioned support, measurement frame, or the like.
0059As shown in FIG. 2, the Y interferometer 16 is separated from the straight line parallel to the Y axis passing through the projection center (optical axis AX, see FIG. 1) of the projection optical system PL by the same distance to the -X side and + X side. Length measurement beam B4 along the length measurement axis in the Y-axis direction<sub>1</sub>, B4<sub>2</sub>Is projected onto the reflecting surface 17a of the wafer table WTB, and by receiving the reflected light of each, the length measuring beam B4 of the wafer table WTB<sub>1</sub>, B4<sub>2</sub>The position (Y position) in the Y-axis direction at the irradiation point of is detected. In Fig. 1, the length measuring beam B4<sub>1</sub>, B4<sub>2</sub>Is typically shown as the length measuring beam B4.
0060In addition, the Y interferometer 16 has a length measuring beam B4.<sub>1</sub>, B4<sub>2</sub>The length-measuring beam B3 is projected toward the reflecting surface 41a along the length-measuring axis in the Y-axis direction at a predetermined interval in the Z-axis direction, and the length-measuring beam B3 reflected by the reflecting surface 41a is received. As a result, the Y position of the reflecting surface 41a (that is, the wafer stage WST) of the moving mirror 41 is detected.
0061The main controller 20 is the length measuring beam B4 of the Y interferometer 16.<sub>1</sub>, B4<sub>2</sub>The Y position (more correctly, the displacement ΔY in the Y-axis direction) of the reflecting surface 17a, that is, the wafer table WTB (wafer stage WST) is calculated based on the average value of the measured values of the length measuring axis corresponding to. The main controller 20 is a length measuring beam B4.<sub>1</sub>, B4<sub>2</sub>Displacement (yaw amount) Δθz in the rotation direction (θz direction) around the Z axis of the wafer table WTB from the difference in the measured values of the length measurement axis corresponding to<sup>(Y)</sup>Is calculated. Further, the main control device 20 calculates the displacement (pitching amount) Δθx of the wafer stage WST in the θx direction based on the Y position (displacement ΔY in the Y-axis direction) on the reflection surface 17a and the reflection surface 41a.
0062Further, as shown in FIG. 2, the X interferometer 126 has a length measuring beam B5 along the length measuring axes of two axes separated by the same distance with respect to the straight line LH in the X axis direction passing through the optical axis of the projection optical system PL.<sub>1</sub>, B5<sub>2</sub>Is projected onto the wafer table WTB, and the main controller 20 uses the length measuring beam B5.<sub>1</sub>, B5<sub>2</sub>The position of the wafer table WTB in the X-axis direction (X position, more correctly, the displacement ΔX in the X-axis direction) is calculated based on the measured value of the length measurement axis corresponding to. Further, the main controller 20 is a length measuring beam B5.<sub>1</sub>, B5<sub>2</sub>Displacement of the wafer table WTB in the θz direction (yaw amount) Δθz from the difference in the measured values of the length measurement axis corresponding to<sup>(X)</sup>Is calculated. Δθz obtained from the X interferometer 126<sup>(X)</sup>And Δθz obtained from Y interferometer 16.<sup>(Y)</sup>Are equal to each other and represent the displacement (yaw amount) Δθz of the wafer table WTB in the θz direction.
0063Further, as shown by the dotted line in FIG. 2, the length measuring beam B7 is emitted from the X interferometer 128 along the length measuring axis parallel to the X axis. This X interferometer 128 actually has the unloading position UP and the loading position LP along the length measuring axis parallel to the X axis connecting the unloading position UP and the loading position LP (see Fig. 3), which will be described later. The length measuring beam B7 is projected onto the reflecting surface 17b of the wafer table WTB located in the vicinity. Further, as shown in FIG. 2, the length measuring beam B6 is projected from the X interferometer 127 onto the reflecting surface 17b of the wafer table WTB. In reality, the length measuring beam B6 is projected onto the reflecting surface 17b of the wafer table WTB along the length measuring axis parallel to the X axis passing through the detection center of the primary alignment system AL1.
0064The main controller 20 can also obtain the displacement ΔX of the wafer table WTB in the X-axis direction from the measured values of the length measuring beam B6 of the X interferometer 127 and the measured values of the length measuring beam B7 of the X interferometer 128. .. However, the arrangement of the three X interferometers 126,127,128 is different in the Y-axis direction, with the X interferometer 126 at the time of exposure shown in FIG. 14 and the X interferometer 127 at the time of wafer alignment shown in FIG. 128 is used during loading of the wafers shown in FIGS. 18 and 19 and during unloading shown in FIG.
0065Further, the length measuring beams B1 and B2 along the Y axis are projected from the Z interferometers 43A and 43B toward the moving mirror 41, respectively. These length measuring beams B1 and B2 are incident on the reflecting surfaces 41b and 41c of the moving mirror 41 at predetermined angles of incidence (referred to as θ / 2), respectively. Then, the length measuring beams B1 and B2 are reflected by the reflecting surfaces 41b and 41c, respectively, and are vertically incident on the reflecting surfaces of the fixed mirrors 47A and 47B. Then, the length-measuring beams B1 and B2 reflected by the reflecting surfaces of the fixed mirrors 47A and 47B are reflected again by the reflecting surfaces 41b and 41c (returning the optical path at the time of incident in the opposite direction), and the Z interferometers 43A and 43B. Is received by.
0066Here, assuming that the displacement of the wafer stage WST (that is, the moving mirror 41) in the Y-axis direction is ΔYo and the displacement in the Z-axis direction is ΔZo, the optical path length of the length-measuring beam B1 received by the Z interferometers 43A and 43B. The change ΔL1 and the optical path length change ΔL2 of the length measuring beam B2 are represented by the following equations (1) and (2), respectively.
0067ΔL1 = ΔYo × (1 + cosθ)-ΔZo × sinθ ... (1) ΔL2 = ΔYo × (1 + cosθ) + ΔZo × sinθ ... (2) Therefore, from equations (1) and (2), ΔZo and ΔYo can be obtained by the following equations (3) and (4).
0068ΔZo = (ΔL2-ΔL1) / 2sinθ ... (3) ΔYo = (ΔL1 + ΔL2) / {2 (1 + cosθ)} ... (4)
0069The above displacements ΔZo and ΔYo are obtained by the Z interferometers 43A and 43B, respectively. Therefore, the displacements obtained by the Z interferometer 43A are ΔZoR and ΔYoR, and the displacements obtained by the Z interferometer 43B are ΔZoL and ΔYoL. Then, let D be the distance between the length measuring beams B1 and B2 projected by the Z interferometers 43A and 43B in the X-axis direction (see FIG. 2). Under this premise, the displacement (yaw amount) Δθz of the moving mirror 41 (that is, the wafer stage WST) in the θz direction and the displacement (rolling amount) Δθy of the moving mirror 41 (that is, the wafer stage WST) in the θy direction are as follows. It is calculated by equations (5) and (6).
0070Δθz (ΔYoR-ΔYoL) / D ... (5) Δθy (ΔZoL-ΔZoR) / D ... (6) Therefore, the main controller 20 uses the above equations (3) to (6), and based on the measurement results of the Z interferometers 43A and 43B, the displacements of the wafer stage WST with four degrees of freedom ΔZo, ΔYo, Δθz. , Δθy can be calculated.
0071In this way, the main controller 20 can obtain the displacement of the wafer stage WST in the six degrees of freedom direction (Z, X, Y, θz, θx, θy direction) from the measurement result of the interferometer system 118. In the present embodiment, the interferometer system 118 can measure the position information of the wafer stage WST in the 6-DOF direction, but the measurement direction is not limited to the 6-DOF direction and may be a direction of 5 or less degrees of freedom. ..
0072In the present embodiment, the case where the wafer stage WST (91, WTB) is a single stage that can be moved with 6 degrees of freedom has been described, but the present invention is not limited to this, and the stage that can be freely moved in the XY plane is not limited to this. A wafer stage WST is configured by including a main body 91 and a wafer table WTB mounted on the stage main body 91 and capable of microdriving at least in the Z-axis direction, the θx direction, and the θy direction with respect to the stage main body 91. You may. In this case, the moving mirror 41 described above is provided on the wafer table WTB. Further, instead of the reflecting surface 17a and the reflecting surface 17b, a moving mirror made of a plane mirror may be provided on the wafer table WTB.
0073However, in the present embodiment, the position information (position information in the three degrees of freedom direction including the rotation information in the θz direction) in the XY plane of the wafer stage WST (wafer table WTB) is mainly measured by the encoder system described later. The measured values of the interferometers 16,126,127 are used to correct (calibrate) long-term fluctuations in the measured values of the encoder system (for example, due to changes in the scale over time), or to back up when an encoder output error occurs. Used for In the present embodiment, of the position information in the 6-degree-of-degree direction of the wafer stage WST, the position information in the 3-degree-of-degree direction including the X-axis direction, the Y-axis direction and the θz direction is measured by the encoder system described later, and the rest. The position information in the three-degree-of-freedom directions, that is, the Z-axis direction, the θx direction, and the θy direction is measured by a measurement system having a plurality of Z sensors, which will be described later. Here, the position information in the remaining three degrees of freedom direction may be measured by both the measurement system and the interferometer system 118. For example, the measurement system may measure the position information in the Z-axis direction and the θy direction, and the interferometer system 118 may measure the position information in the θx direction.
0074At least a part of the interferometer system 118 (for example, an optical system) is provided in the main frame holding the projection unit PU, or is provided integrally with the projection unit PU which is suspended and supported as described above. However, in the present embodiment, it is provided in the measurement frame described above.
0075The measurement stage MST includes the stage main body 92 described above and a measurement table MTB mounted on the stage main body 92. The measurement table MTB is mounted on the stage body 92 via a Z leveling mechanism (not shown). However, the present invention is not limited to this, and for example, a measurement stage MST having a so-called coarse and fine movement structure in which the measurement table MTB can be finely moved in the X-axis direction, the Y-axis direction, and the θz direction with respect to the stage main body 92 may be adopted. Alternatively, the measurement table MTB may be fixed to the stage main body 92, and the entire measurement stage MST including the measurement table MTB and the stage main body 92 may be driven in the direction of 6 degrees of freedom.
0076The measurement table MTB (and the stage body 92) is provided with various measurement members. As the measuring member, for example, as shown in FIGS. 2 and 5 (A), an illuminance unevenness sensor 94 having a pinhole-shaped light receiving portion that receives illumination light IL on the image plane of the projection optical system PL 94. , Spatial image measuring instrument 96 that measures the spatial image (projected image) of the pattern projected by the projection optical system PL, and the Shack-Hartman method disclosed in, for example, International Publication No. 03/065428. Wave surface aberration measuring instrument 98 and the like are adopted. As the wave surface aberration measuring instrument 98, for example, the one disclosed in International Publication No. 99/60361 (corresponding European Patent Application Publication No. 1079223) can also be used.
0077As the illuminance unevenness sensor 94, for example, one having the same configuration as that disclosed in Japanese Patent Application Laid-Open No. 57-117238 (corresponding US Pat. No. 4,465,368) can be used. Further, as the spatial image measuring instrument 96, for example, one having the same configuration as that disclosed in Japanese Patent Application Laid-Open No. 2002-14005 (corresponding US Patent Application Publication No. 2002/0041377) can be used. .. In the present embodiment, three measuring members (94, 96, 98) are provided in the measuring stage MST, but the type and / or number of measuring members is not limited to this. As the measuring member, for example, a transmittance measuring instrument for measuring the transmittance of the projection optical system PL, and / or a measuring instrument for observing the above-mentioned local immersion device 8, for example, the nozzle unit 32 (or the tip lens 191), etc. May be used. Further, a member different from the measurement member, for example, a cleaning member for cleaning the nozzle unit 32, the tip lens 191 and the like may be mounted on the measurement stage MST.
0078In this embodiment, as can be seen from FIG. 5 (A), the frequently used sensors, the illuminance unevenness sensor 94, the spatial image measuring instrument 96, etc. are the center line CL (Y-axis passing through the center) of the measurement stage MST. It is placed on top. Therefore, in the present embodiment, the measurement using these sensors can be performed by moving the measurement stage MST only in the Y-axis direction without moving it in the X-axis direction.
0079In addition to the above sensors, for example, the illumination light IL is received on the image plane of the projection optical system PL disclosed in Japanese Patent Application Laid-Open No. 11-16816 (corresponding US Patent Application Publication No. 2002/0061469). An illuminance monitor having a light receiving portion having a predetermined area may be adopted, and it is desirable that this illuminance monitor is also arranged on the center line.
0080In the present embodiment, the illumination light IL is used in response to the immersion exposure in which the wafer W is exposed by the exposure light (illuminance light) IL via the projection optical system PL and the liquid (water) Lq. The above-mentioned illuminance unevenness sensor 94 (and illuminance monitor), spatial image measuring instrument 96, and wave surface aberration measuring instrument 98 used for the measurement used receive the illumination light IL via the projection optical system PL and water Lq. Become. Further, for each sensor, for example, only a part of the optical system may be mounted on the measurement table MTB (and the stage main body 92), or the entire sensor may be arranged on the measurement table MTB (and the stage main body 92). You may.
0081As shown in FIG. 5B, a frame-shaped mounting member 42 is fixed to the end face on the Y side of the stage body 92 of the measurement stage MST. Further, on the end face on the -Y side of the stage main body 92, a pair of light receiving systems 44 are arranged so as to face the pair of light transmitting systems 36 described above in the vicinity of the center position in the X-axis direction inside the opening of the mounting member 42. Is fixed. Each light receiving system 44 is composed of an optical system such as a relay lens, a light receiving element such as a photomultiplier tube, and a housing for accommodating them. As can be seen from FIGS. 4 (B) and 5 (B) and the above description, in the present embodiment, the wafer stage WST and the measurement stage MST are close to each other within a predetermined distance in the Y-axis direction (contact). In (including the state), the illumination light IL transmitted through each spatial image measurement slit pattern SL of the measurement plate 30 is guided by each of the above-mentioned light transmission systems 36, and is received by each light receiving element inside each light receiving system 44. That is, the measurement plate 30, the light transmitting system 36, and the light receiving system 44 are similar to those disclosed in Japanese Patent Application Laid-Open No. 2002-14005 (corresponding US Patent Application Publication No. 2002/0041377). The spatial image measuring device 45 is configured (see FIG. 6).
0082A confidential bar (hereinafter, abbreviated as "CD bar") 46 as a reference member made of a rod-shaped member having a rectangular cross section extends above the mounting member 42 in the X-axis direction. The CD bar 46 is kinematically supported on the measurement stage MST by a full kinematic mount structure.
0083Since the CD bar 46 serves as a prototype (measurement standard), optical glass ceramics having a low coefficient of thermal expansion, such as Schott AG's Zerodur (trade name), are used as the material. The flatness of the upper surface (surface) of the CD bar 46 is set to be as high as that of a so-called reference flat plate. Further, as shown in FIG. 5A, a reference grid (for example, a diffraction grating) 52 having a Y-axis direction as a periodic direction is provided near the ends on one side and the other side of the CD bar 46 in the longitudinal direction. Each is formed. The pair of reference grids 52 are formed in a symmetrical arrangement with respect to the center of the CD bar 46 in the X-axis direction, that is, the above-mentioned center line CL, separated from each other by a predetermined distance (L).
0084Further, on the upper surface of the CD bar 46, a plurality of reference marks M are formed in an arrangement as shown in FIG. 5 (A). The plurality of reference marks M are formed in an array of three rows in the Y-axis direction at the same pitch, and the arrays of the rows are formed so as to be offset from each other by a predetermined distance in the X-axis direction. As each reference mark M, a two-dimensional mark having dimensions that can be detected by the primary alignment system and the secondary alignment system, which will be described later, is used. The shape (configuration) of the reference mark M may be different from that of the above-mentioned reference mark FM, but in the present embodiment, the reference mark M and the reference mark FM have the same configuration and the same as the alignment mark of the wafer W. It is composed. In this embodiment, the surface of the CD bar 46 and the surface of the measurement table MTB (which may include the above-mentioned measurement member) are also covered with a liquid-repellent film (water-repellent film).
0085The + Y end face and -X end face of the measurement table MTB also have reflective surfaces 19a and 19b similar to those of the wafer table WTB described above (see FIGS. 2 and 5 (A)). The Y interferometer 18 and X interferometer 130 (in FIG. 1, the X interferometer 130 is not shown, see FIG. 2) of the interferometer system 118 (see FIG. 6) are shown on these reflective surfaces 19a and 19b, in FIG. As shown, by projecting an interferometer beam (length measuring beam) and receiving each reflected light, the displacement of each reflecting surface from the reference position, that is, the position information of the measurement stage MST (for example, at least X). (Including position information in the axis and Y-axis directions and rotation information in the θz direction) is measured, and this measured value is supplied to the main control device 20.
0086In the exposure apparatus 100 of the present embodiment, the illustration is omitted in FIG. 1 from the viewpoint of avoiding the complexity of the drawings, but in reality, as shown in FIG. 3, the center of the projection unit PU (the projection optical system PL). A primary having a detection center at a position separated by a predetermined distance from the optical axis to the -Y side on a straight line LV that passes through the optical axis AX (which also coincides with the center of the exposure region IA described above in the present embodiment) and is parallel to the Y axis. The alignment system AL1 is arranged. The primary alignment system AL1 is fixed to the lower surface of a main frame (not shown) via a support member 54. A secondary alignment system AL2 in which detection centers are arranged almost symmetrically with respect to the straight line LV on one side and the other side in the X-axis direction with this primary alignment system AL1 in between.<sub>1</sub>, AL2<sub>2</sub>And AL2<sub>3</sub>, AL2<sub>4</sub>And are provided respectively. That is, five alignment systems AL1, AL2<sub>1</sub>~ AL2<sub>4</sub>The detection centers are located at different positions with respect to the X-axis direction, that is, along the X-axis direction.
0087Each secondary alignment system AL2<sub>n</sub>(n = 1 ~ 4) is the secondary alignment system AL2<sub>4</sub>As is typically shown, an arm 56 that can rotate clockwise and counterclockwise in a predetermined angle range around the center of rotation O in FIG.<sub>n</sub>It is fixed to the tip (rotating end) of (n = 1 to 4). In this embodiment, each secondary alignment system AL2<sub>n</sub>A part of the arm 56 (for example, including an optical system that irradiates the detection region with alignment light and guides the light generated from the target mark in the detection region to the light receiving element)<sub>n</sub>The remaining part is provided on the mainframe that holds the projection unit PU. Secondary alignment system AL2<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>The X position is adjusted by rotating around the rotation center O, respectively. That is, the secondary alignment system AL2<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>The detection area (or detection center) of is independently movable in the X-axis direction. Therefore, the primary alignment system AL1 and the secondary alignment system AL2<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>The relative position of the detection area can be adjusted with respect to the X-axis direction. In this embodiment, the secondary alignment system AL2 is rotated by rotating the arm.<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>It was assumed that the X position of was adjusted, but it is not limited to this, and the secondary alignment system AL2<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>May be provided with a drive mechanism that reciprocates in the X-axis direction. In addition, the secondary alignment system AL2<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>At least one of them may be movable not only in the X-axis direction but also in the Y-axis direction. In addition, each secondary alignment system AL2<sub>n</sub>Part of it is arm 56<sub>n</sub>Because it is moved by, by a sensor (not shown), such as an interferometer, or an encoder, the arm 56<sub>n</sub>The position information of a part of it fixed to is measurable. This sensor is a secondary alignment system AL2<sub>n</sub>It is sufficient to measure the position information in the X-axis direction of, but it is also possible to measure the position information in other directions, for example, the Y-axis direction and / or the rotation direction (including at least one of the θx and θy directions).
0088Each arm 56<sub>n</sub>On the top of the vacuum pad 58 consisting of differential exhaust type air bearings<sub>n</sub>(n = 1 ~ 4) is provided. Also, arm 56<sub>n</sub>Is a rotary drive mechanism 60 including a motor, etc.<sub>n</sub>According to (n = 1 to 4, not shown in FIG. 3, see FIG. 6), the rotation is possible according to the instruction of the main controller 20. The main controller 20 is an arm 56<sub>n</sub>After adjusting the rotation of each vacuum pad 58<sub>n</sub>Activate each arm 56<sub>n</sub>Is adsorbed and fixed to a main frame (not shown). As a result, each arm 56<sub>n</sub>After adjusting the rotation angle, that is, the primary alignment system AL1 and the four secondary alignment systems AL2<sub>1</sub>~ AL2<sub>4</sub>The desired positional relationship of is maintained.
0089Mainframe arm 56<sub>n</sub>If the portion facing the vacuum pad 58 is a magnetic material, an electromagnet may be used instead of the vacuum pad 58.
0090In this embodiment, the primary alignment system AL1 and the four secondary alignment systems AL2<sub>1</sub>~ AL2<sub>4</sub>For example, the target mark is irradiated with a broadband detection light beam that does not expose the resist on the wafer, and the image of the target mark imaged on the light receiving surface by the reflected light from the target mark and an index (not shown) (each alignment). An image processing FIA (Field Image Alignment) system is used in which an image of an index pattern (index pattern on an index plate provided in the system) is imaged using an image sensor (CCD, etc.) and the imaging signals are output. ing. Primary alignment system AL1 and 4 secondary alignment systems AL2<sub>1</sub>~ AL2<sub>4</sub>The imaging signals from each of the above are supplied to the main control device 20 of FIG.
0091Each of the above alignment systems is not limited to the FIA system, and the target mark is irradiated with coherent detection light to detect scattered light or diffracted light generated from the target mark, or two types generated from the target mark. Of course, it is possible to use an alignment sensor that detects by interfering with diffracted light (for example, diffracted light of the same order or diffracted light diffracted in the same direction) alone or in combination as appropriate. Further, in this embodiment, five alignment systems AL1 and AL2 are used.<sub>1</sub>~ AL2<sub>4</sub>However, the number is not limited to 5, and may be 2 or more and 4 or less, or 6 or more, and may be an even number instead of an odd number. Further, in the present embodiment, five alignment systems AL1 and AL2<sub>1</sub>~ AL2<sub>4</sub>Is fixed to the lower surface of the main frame that holds the projection unit PU via the support member 54, but the present invention is not limited to this, and may be provided, for example, on the measurement frame described above. In addition, alignment system AL1, AL2<sub>1</sub>~ AL2<sub>4</sub>Detects the alignment mark of the wafer W and the reference mark of the CD bar 46, and is therefore simply referred to as a mark detection system in this embodiment.
0092In the exposure apparatus 100 of the present embodiment, as shown in FIG. 3, four head units 62A to 62D of the encoder system are arranged so as to surround the nozzle unit 32 described above from all sides. Although these head units 62A to 62D are not shown in FIG. 3 from the viewpoint of avoiding confusion in the drawings, they are actually suspended from the main frame holding the projection unit PU described above via a support member. It is fixed in the state. When the projection unit PU is suspended and supported, the head units 62A to 62D may be suspended and supported integrally with the projection unit PU, or may be provided in the measurement frame described above.
0093The head units 62A and 62C are arranged on the + X side and -X side of the projection unit PU with the X-axis direction as the longitudinal direction, respectively, symmetrically with respect to the optical axis AX of the projection optical system PL and separated from the optical axis AX by approximately the same distance. Has been done. Further, the head units 62B and 62D are arranged on the + Y side and the -Y side of the projection unit PU, respectively, with the Y-axis direction as the longitudinal direction and substantially the same distance from the optical axis AX of the projection optical system PL.
0094As shown in FIG. 3, a plurality of head units 62A and 62C are arranged at predetermined intervals on a straight line LH that passes through the optical axis AX of the projection optical system PL along the X-axis direction and is parallel to the X-axis. It has 6) Y heads 64. The head unit 62A is the Y scale 39Y mentioned above.<sub>1</sub>Multi-eye (here, 6 eyes) Y linear encoder (hereinafter, "Y encoder" or "encoder" as appropriate) that measures the position (Y position) of the wafer stage WST (wafer table WTB) in the Y-axis direction using (Abbreviated as) Consists of 70A (see Fig. 6). Similarly, the head unit 62C is the Y scale 39Y described above.<sub>2</sub>Is used to configure a multi-eye (here, 6-eye) Y encoder 70C (see FIG. 6) that measures the Y position of the wafer stage WST (wafer table WTB). Here, the distance between the adjacent Y heads 64 (that is, the measurement beam) included in the head units 62A and 62C is the above-mentioned Y scale 39Y.<sub>1</sub>, 39Y<sub>2</sub>Is set narrower than the width in the X-axis direction (more accurately, the length of the grid line 38). Further, among the plurality of Y heads 64 provided by the head units 62A and 62C, the innermost Y head 64 is arranged as close as possible to the optical axis of the projection optical system PL, so that the lens barrel of the projection optical system PL is arranged as close as possible. It is fixed to the lower end of 40 (more accurately, the side of the nozzle unit 32 that surrounds the tip lens 191).
0095As shown in FIG. 3, the head unit 62B includes a plurality of head units 66 arranged at predetermined intervals along the Y-axis direction on the straight line LV, in this case, seven X heads 66. In addition, there are a plurality of head units 62D arranged at predetermined intervals on the straight line LV, here 11 (however, in FIG. 3, 3 out of 11 overlapping with the primary alignment system AL1 are not shown). It has 66. The head unit 62B is the above-mentioned X scale 39X.<sub>1</sub>Multi-eye (here, 7 eyes) X linear encoder (hereinafter, "X encoder" or "encoder" as appropriate) that measures the position (X position) of the wafer stage WST (wafer table WTB) in the X-axis direction using (Abbreviated as) 70B (see Fig. 6). In addition, the head unit 62D is the above-mentioned X scale 39X.<sub>2</sub>Is used to configure a multi-eye (here, 11-eye) X encoder 70D (see FIG. 6) that measures the X position of the wafer stage WST (wafer table WTB). Further, in the present embodiment, for example, two X heads 66 out of the 11 X heads 66 included in the head unit 62D at the time of alignment described later are X scale 39X.<sub>1</sub>, X scale 39X<sub>2</sub>May face each other at the same time. In this case, X scale 39X<sub>1</sub>The X linear encoder 70B is composed of the X head 66 and the X head 66 facing it, and the X scale 39X.<sub>2</sub>The X linear encoder 70D is composed of the X head 66 and the X head 66 facing the X linear encoder.
0096Here, a part of the 11 X heads 66, here three X heads, are attached to the lower surface side of the support member 54 of the primary alignment system AL1. In addition, the distance between the adjacent X heads 66 (measurement beams) of the head units 62B and 62D, respectively, is the above-mentioned X scale 39X.<sub>1</sub>, 39X<sub>2</sub>Is set narrower than the width in the Y-axis direction (more accurately, the length of the grid line 37). Further, among the plurality of X heads 66 included in the head units 62B and 62D, the X head 66 located on the innermost side is the lens barrel of the projection optical system PL in order to be arranged as close as possible to the optical axis of the projection optical system PL. It is fixed to the lower end of the lens (more accurately, the side of the nozzle unit 32 that surrounds the tip lens 191).
0097Furthermore, the secondary alignment system AL2<sub>1</sub>-X side, secondary alignment system AL2<sub>4</sub>On the + X side of the Y head 64y, the detection points are arranged on a straight line parallel to the X axis passing through the detection center of the primary alignment system AL1 and almost symmetrically with respect to the detection center.<sub>1</sub>, 64y<sub>2</sub>Are provided respectively. Y head 64y<sub>1</sub>, 64y<sub>2</sub>The interval is set to be substantially equal to the above-mentioned distance L. Y head 64y<sub>1</sub>, 64y<sub>2</sub>Is a Y scale 39Y in the state shown in FIG. 3 where the center of the wafer W on the wafer stage WST is on the straight line LV.<sub>2</sub>, 39Y<sub>1</sub>Are designed to face each other. Y head 64y for alignment operation described later<sub>1</sub>, 64y<sub>2</sub>Y scale 39Y facing<sub>2</sub>, 39Y<sub>1</sub>Are placed respectively, this Y head 64y<sub>1</sub>, 64y<sub>2</sub>(That is, these Y heads 64y<sub>1</sub>, 64y<sub>2</sub>The Y position (and θz rotation) of the wafer stage WST is measured by the Y encoders 70C, 70A) configured by.
0098Further, in the present embodiment, a pair of reference grids 52 and a Y head 64y of the CD bar 46 are used during baseline measurement of the secondary alignment system, which will be described later.<sub>1</sub>, 64y<sub>2</sub>And each face each other, Y head 64y<sub>1</sub>, 64y<sub>2</sub>The Y position of the CD bar 46 is measured at the position of each reference grid 52 by the reference grid 52 facing the CD bar 46. In the following, the Y head 64y facing the reference grid 52 respectively<sub>1</sub>, 64y<sub>2</sub>The encoders composed of these are called Y-axis linear encoders 70E and 70F (see Fig. 6).
0099The six linear encoders 70A to 70F described above measure the position information in each measurement direction of the wafer stage WST with a resolution of, for example, about 0.1 nm, and the measured values (measurement information) are supplied to the main control device 20. To. The main controller 20 controls the position of the wafer table WTB in the XY plane based on the measured values of the linear encoders 70A to 70D, and the θz direction of the CD bar 46 based on the measured values of the linear encoders 70E and 70F. Control the rotation of. The configuration of the linear encoder will be described later.
0100In the exposure apparatus 100 of the present embodiment, a position measuring apparatus for measuring the positional information of the wafer W in the Z-axis direction is provided. In the present embodiment, as this position measuring device, as shown in FIG. 3, for example, Japanese Patent Application Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332) comprising an irradiation system 90a and a light receiving system 90b. A oblique-incident multipoint focal position detection system (hereinafter abbreviated as "multipoint AF system") having the same configuration as the one disclosed is provided. In the present embodiment, as an example, the irradiation system 90a is arranged on the -Y side of the -X end of the above-mentioned head unit 62C, and in a state facing this, -Y of the + X end of the above-mentioned head unit 62A. The light receiving system 90b is arranged on the side.
0101Although not shown, the plurality of detection points of this multipoint AF system (90a, 90b) are arranged at predetermined intervals along the X-axis direction on the test surface. In this embodiment, for example, they are arranged in a matrix of 1 row and M columns (M is the total number of detection points) or 2 rows and N columns (N is 1/2 of the total number of detection points). In FIG. 3, a plurality of detection points to which each detection beam is irradiated are not shown individually, but are shown as an elongated detection region (beam region) AF extending in the X-axis direction between the irradiation system 90a and the light receiving system 90b. There is. Since the length in the X-axis direction of this detection area AF is set to be about the same as the diameter of the wafer W, it is only necessary to scan the wafer W once in the Y-axis direction in the Z-axis direction on almost the entire surface of the wafer W. Position information (surface position information) can be measured. Further, this detection area AF is the above-mentioned immersion region 14 (exposure region IA) and the alignment system (AL1, AL2) in the Y-axis direction.<sub>1</sub>, AL2<sub>2</sub>, AL2<sub>3</sub>, AL2<sub>4</sub>Since it is arranged between the detection area of), it is possible to perform the detection operation in parallel in the multipoint AF system and the alignment system. The multipoint AF system may be provided on a main frame or the like that holds the projection unit PU, but in the present embodiment, it is provided on the measurement frame described above.
0102It should be noted that the plurality of detection points are arranged in 1 row M columns or 2 rows N columns, but the number of rows and / or the number of columns is not limited to this. However, when the number of rows is 2 or more, it is preferable that the positions of the detection points in the X-axis direction are different even between different rows. Further, although the plurality of detection points are arranged along the X-axis direction, the present invention is not limited to this, and all or a part of the plurality of detection points may be arranged at different positions in the Y-axis direction. For example, a plurality of detection points may be arranged along a direction that intersects both the X-axis and the Y-axis. That is, it suffices that the plurality of detection points have different positions at least in the X-axis direction. Further, in the present embodiment, the detection beam is irradiated to a plurality of detection points, but for example, the detection beam may be irradiated to the entire area of the detection region AF. Further, the length of the detection area AF in the X-axis direction does not have to be about the same as the diameter of the wafer W.
0103In the present embodiment, of the plurality of detection points of the multipoint AF system, each pair is arranged symmetrically with respect to the above-mentioned straight line LV in the vicinity of the detection points located at both ends, that is, in the vicinity of both ends of the beam region AF. Surface position sensors for Z position measurement (hereinafter abbreviated as "Z sensor") 72a, 72b, and 72c, 72d are provided. These Z sensors 72a to 72d are fixed to the lower surface of a main frame (not shown). The Z sensors 72a to 72d irradiate the wafer table WTB with light from above, receive the reflected light, and provide position information in the Z-axis direction orthogonal to the XY plane of the surface of the wafer table WTB at the irradiation point of the light. A sensor for measuring, for example, an optical displacement sensor (optical pickup type sensor) having a configuration like an optical pickup used in a CD drive device or the like is used. The Z sensors 72a to 72d may be provided in the measurement frame or the like described above.
0104Further, the head unit 62C described above is located on one side and the other side of the straight line LH in the X-axis direction connecting the plurality of Y heads 64, along two straight lines parallel to the straight line LH and mutually. Multiple Z-sensors 74 (6 each, 12 in total) arranged at predetermined intervals corresponding to<sub>i, j</sub>It has (i = 1,2, j = 1,2, ......, 6). In this case, a pair of Z sensors 74<sub>1,j</sub>、74<sub>2,j</sub>Are arranged symmetrically with respect to the straight line LH. In addition, multiple pairs (6 pairs here) of Z sensors 74<sub>1,j</sub>、74<sub>2,j</sub>And the plurality of Y heads 64 are arranged alternately in the X-axis direction. Each Z sensor 74<sub>i, j</sub>As the above-mentioned Z sensor 72a to 72d, an optical pickup type sensor similar to the above-mentioned Z sensor 72a to 72d is used.
0105Here, each pair of Z sensors 74 located symmetrically with respect to the straight line LH.<sub>1,j</sub>,74<sub>2,j</sub>The interval is set to be the same as the interval of the Z sensors 72a and 72b described above. Also, a pair of Z sensors 74<sub>1,4</sub>,74<sub>2,4</sub>Is located on the same straight line in the Y-axis direction as the Z sensors 72a and 72b.
0106Further, the above-mentioned head unit 62A has the above-mentioned plurality of Z sensors 74 with respect to the above-mentioned linear LV.<sub>i, j</sub>Multiple, here 12 Z sensors 76 arranged symmetrically with<sub>p, q</sub>It has (p = 1,2, q = 1,2, ......, 6). Each Z sensor 76<sub>p, q</sub>As the above-mentioned Z sensor 72a to 72d, an optical pickup type sensor similar to the above-mentioned Z sensor 72a to 72d is used. Also, a pair of Z sensors 76<sub>1,3</sub>,76<sub>2,3</sub>Is located on the same straight line in the Y-axis direction as the Z sensors 72c and 72d. Z sensor 74<sub>i, j</sub>、76<sub>p, q</sub>Is provided on, for example, the above-mentioned main frame or measurement frame. Further, in the present embodiment, Z sensors 72a to 72d, 74<sub>i, j</sub>、76<sub>p, q</sub>The measurement system having the above measures the position information of the wafer stage WST in the Z-axis direction by one or a plurality of Z sensors facing the scale described above. Therefore, in the exposure operation, the Z sensor 74 used for position measurement according to the movement of the wafer stage WST.<sub>i, j</sub>、76<sub>p, q</sub>Is switched. Furthermore, in the exposure operation, Y scale 39Y<sub>1</sub>And at least one Z sensor 76<sub>p, q</sub>Are facing each other and Y scale 39Y<sub>2</sub>And at least one Z sensor 74<sub>i, j</sub>Are opposed to each other. Therefore, the measurement system can measure not only the position information in the Z-axis direction of the wafer stage WST but also the position information (rolling) in the θy direction. Further, in the present embodiment, each Z sensor of the measurement system detects the lattice surface of the scale (the surface on which the diffraction grating is formed), but detects a surface different from the lattice surface, for example, one surface of the cover glass covering the lattice surface. It may be something to do.
0107In FIG. 3, the measurement stage MST is not shown, and the immersion region formed by the water Lq held between the measurement stage MST and the tip lens 191 is indicated by reference numeral 14. Further, in FIG. 3, reference numeral 78 indicates, for example, down the dry air whose temperature has been adjusted to a predetermined temperature in the vicinity of the beam path of the multipoint AF system (90a, 90b) as shown by the white arrows in FIG. The local air conditioning system that blows air in the flow is shown. Further, the reference numeral UP indicates an unloading position where the wafer is unloaded on the wafer table WTB, and the reference numeral LP indicates a loading position where the wafer is loaded onto the wafer table WTB. In the present embodiment, the unloading position UP and the loading position LP are set symmetrically with respect to the straight line LV. The unloading position UP and the loading position LP may be set to the same position.
0108FIG. 6 shows the main configuration of the control system of the exposure apparatus 100. This control system is mainly composed of a main control device 20 composed of a microprocessor (or workstation) that controls the entire device in an integrated manner. Correction information, which will be described later, is stored in the memory 34, which is an external storage device connected to the main control device 20. In FIG. 6, various sensors provided in the measurement stage MST such as the above-mentioned illuminance unevenness sensor 94, spatial image measuring instrument 96, and wave surface aberration measuring instrument 98 are collectively shown as a sensor group 99.
0109In the exposure apparatus 100 of the present embodiment configured as described above, the arrangement of the X scale and the Y scale on the wafer table WTB as described above and the arrangement of the X head and the Y head as described above are adopted. , FIG. 7 (A), FIG. 7 (B), etc., always in the effective stroke range of the wafer stage WST (that is, the range moved for alignment and exposure operation in this embodiment). X scale 39X<sub>1</sub>, 39X<sub>2</sub>At least one of the 18 X heads belonging to the head units 62B and 62D faces at least one of the X heads 66, and the Y scale 39Y.<sub>1</sub>, 39Y<sub>2</sub>At least one Y head 64 or Y head 64y belonging to each of the head units 62A and 62C.<sub>1</sub>, 64y<sub>2</sub>Are facing each other. That is, at least one of the corresponding heads faces at least three of the four scales.
0110In FIGS. 7 (A) and 7 (B), the heads facing the corresponding X scale or Y scale are circled and shown.
0111Therefore, in the effective stroke range of the wafer stage WST described above, the main controller 20 sets the stage drive system based on the measured values of at least three encoders of the encoders 70A and 70C and at least one of the encoders 70B and 70D. By controlling each of the motors constituting the 124, the position information (including the rotation information in the θz direction) of the wafer stage WST in the XY plane can be controlled with high accuracy. Since the influence of air fluctuations on the measured values of encoders 70A to 70D is negligibly smaller than that of the interferometer, the short-term stability of the measured values caused by the air fluctuations is much better than that of the interferometer.
0112Further, as shown by the white arrows in FIG. 7A, when the wafer stage WST is driven in the X-axis direction, the Y head 64 that measures the position of the wafer stage WST in the Y-axis direction is shown in the figure. Arrow e<sub>1</sub>, e<sub>2</sub>As shown by, it switches to the adjacent Y head 64 in sequence. For example, the Y head 64 surrounded by a solid line circle is switched to the Y head 64 circled by a dotted line. Therefore, before and after the switching, the measurement value connection processing is performed. That is, in the present embodiment, in order to smoothly switch the Y head 64 and connect the measured values, as described above, the distance between the adjacent Y head 64 provided in the head units 62A and 62C is set to the Y scale 39Y.<sub>1</sub>, 39Y<sub>2</sub>It is set narrower than the width in the X-axis direction of.
0113Further, in the present embodiment, as described above, the distance between the adjacent X heads 66 included in the head units 62B and 62D is the above-mentioned X scale 39X.<sub>1</sub>, 39X<sub>2</sub>Since the width is set narrower than the width in the Y-axis direction of, as described above, when the wafer stage WST is driven in the Y-axis direction as shown by the white arrow in FIG. 7 (B), the wafer stage is set. The X-head 66, which measures the position of the WST in the X-axis direction, is sequentially switched to the adjacent X-head 66 (for example, the X-head 66 circled by a solid line is switched to the X-head 66 circled by a dotted line). Before and after the switching, the measurement value is connected.
0114Next, the configurations of the encoders 70A to 70F will be described by taking the Y encoder 70A, which is enlarged and shown in FIG. 8A, as a representative. In Fig. 8 (A), Y scale 39Y<sub>1</sub>Shows one Y-head 64 of the head unit 62A that irradiates the detection light (measurement beam).
0115The Y head 64 is roughly divided into three parts: an irradiation system 64a, an optical system 64b, and a light receiving system 64c.
0116The irradiation system 64a is arranged on the optical path of a light source that emits the laser beam LB in a direction forming 45 ° with respect to the Y-axis and the Z-axis, for example, a semiconductor laser LD and a laser beam LB emitted from the semiconductor laser LD. Including the focusing lens L1.
0117The optical system 64b includes a polarizing beam splitter PBS whose separation surface is parallel to the XZ plane, a pair of reflection mirrors R1a, R1b, lenses L2a, L2b, and a quarter wave plate (hereinafter referred to as λ / 4 plate). It is equipped with WP1a, WP1b, and reflection mirrors R2a, R2b, etc.
0118The light receiving system 64c includes a polarizer (photon detector), a photodetector, and the like.
0119In this Y encoder 70A, the laser beam LB emitted from the semiconductor laser LD is incident on the polarization beam splitter PBS via the lens L1, and is polarized and separated into two beams LB.<sub>1</sub>, LB<sub>2</sub>Will be. Polarization Beam Splitter Beam LB through PBS<sub>1</sub>Is a Y scale 39Y through a reflective mirror R1a<sub>1</sub>Beam LB that reaches the reflective diffraction grating RG formed in and is reflected by the polarizing beam splitter PBS<sub>2</sub>Reach the reflective diffraction grating RG via the reflective mirror R1b. Here, "polarized light separation" means that the incident beam is separated into a P-polarized light component and an S-polarized light component.
0120Beam LB<sub>1</sub>, LB<sub>2</sub>Diffraction beams of a predetermined order generated from the diffraction grating RG by the irradiation of, for example, the first-order diffraction beams are converted into circularly polarized light by the λ / 4 plates WP1b and WP1a via the lenses L2b and L2a, respectively, and then the reflection mirror R2b, It is reflected by R2a, passes through the λ / 4 plates WP1b and WP1a again, and follows the same optical path as the outward path in the opposite direction to reach the polarizing beam splitter PBS.
0121Polarization Beam Splitter Each of the two beams reaching the PBS has its polarization direction rotated 90 degrees with respect to the original direction. Therefore, the beam LB that first passed through the polarizing beam splitter PBS<sub>1</sub>The primary diffraction beam of is reflected by the polarizing beam splitter PBS and incident on the light receiving system 64c, and the beam LB previously reflected by the polarizing beam splitter PBS.<sub>2</sub>The primary diffraction beam of the above beam LB is transmitted through the polarizing beam splitter PBS.<sub>1</sub>It is synthesized coaxially with the primary diffraction beam of the above and is incident on the light receiving system 64c.
0122Then, the polarization directions of the above two primary diffracted beams are aligned by the analyzer inside the light receiving system 64c, and they interfere with each other to become interfering light. It is converted into an electric signal according to the intensity.
0123As can be seen from the above explanation, in the Y encoder 70A, the optical path lengths of the two beams that interfere with each other are extremely short and almost equal, so that the influence of air fluctuation can be almost ignored. And Y scale 39Y<sub>1</sub>When (that is, the wafer stage WST) moves in the measurement direction (in this case, the Y-axis direction), the phase of each of the two beams changes and the intensity of the interference light changes. The change in the intensity of the interference light is detected by the light receiving system 64c, and the position information corresponding to the change in the intensity is output as the measured value of the Y encoder 70A. Other encoders 70B, 70C, 70D, etc. are also configured in the same manner as the encoder 70A.
0124On the other hand, the wafer stage WST moves in a direction different from the Y-axis direction, and the head 64 and the Y scale 39Y<sub>1</sub>If a relative motion other than the desired direction (relative motion in the non-measurement direction) occurs between and, in most cases, this causes a measurement error in the Y encoder 70A. Hereinafter, the mechanism by which this measurement error occurs will be described.
0125First, two return luminous flux LB<sub>1</sub>, LB<sub>2</sub>The intensity of the interference light synthesized from and the Y scale 39Y<sub>2</sub>The relationship of displacement (relative displacement with Y head 64) of (reflection type diffraction grating RG) is derived.
0126In FIG. 8B, the luminous flux LB reflected by the reflector R1a<sub>1</sub>Is an angle θ on the reflective diffraction grating RG<sub>a0</sub>Incident at, n<sub>a</sub>The next refracted light is at an angle θ<sub>a1</sub>Suppose that it occurs in. Then, the return luminous flux reflected by the reflector R2a and following the return path has an angle θ on the reflection type diffraction grating RG.<sub>a1</sub>Incident at. Then, diffracted light is generated again. Here, the angle θ<sub>a0</sub>The diffracted light generated in the above and following the original optical path toward the reflector R1a is n of the same order as the diffracted light generated in the outward path.<sub>a</sub>This is the next refracted light.
0127On the other hand, the luminous flux LB reflected by the reflector R1b<sub>2</sub>Is the angle θ<sub>b0</sub>At the reflection type diffraction grating RG, n<sub>b b</sub>The next refracted light is at an angle θ<sub>b1</sub>Occurs in. It is assumed that this diffracted light is reflected by the reflecting mirror R2b and returns to the reflecting mirror R1b by following the same optical path.
0128In this case, two return luminous flux LB<sub>1</sub>, LB<sub>2</sub>The intensity I of the interfering light synthesized from is the two return luminous flux LB at the light receiving position of the photodetector.<sub>1</sub>, LB<sub>2</sub>The phase difference (phase difference) φ between them depends on I1 + cosφ. However, two luminous flux LB<sub>1</sub>, LB<sub>2</sub>The intensities of were equal to each other.
0129Here, the phase difference φ is theoretically obtained by the following equation (7), although the details of the detailed derivation method are omitted.
0130φ = KΔL + 4π (n<sub>b b</sub>-n<sub>a</sub>) ΔY / p + 2KΔZ (cosθ)<sub>b1</sub>+ cosθ<sub>b0</sub>-cosθ<sub>a1</sub>-cosθ<sub>a0</sub>) ... (7) Where KΔL is the two luminous flux LB<sub>1</sub>, LB<sub>2</sub>Phase difference due to the optical path difference ΔL, ΔY is the displacement of the reflective diffraction grating RG in the + Y direction, ΔZ is the displacement of the reflective diffraction grating RG in the + Z direction, p is the pitch of the diffraction grating, n<sub>b b</sub>, n<sub>a</sub>Is the diffraction order of each of the above-mentioned diffracted lights.
0131Here, it is assumed that the encoder is configured so as to satisfy the optical path difference ΔL = 0 and the symmetry represented by the following equation (8).
0132θ<sub>a0</sub>= θ<sub>b0</sub>, Θ<sub>a1</sub>= θ<sub>b1</sub> ... (8) In that case, the number in parentheses in the third term on the right side of equation (7) becomes zero, and at the same time n<sub>b b</sub>= -n<sub>a</sub>Since (= n) is satisfied, the following equation (9) is obtained.
0133φ<sub>sym</sub>(ΔY) = 2πΔY / (p / 4n) ... (9) From the above equation (9), the phase difference φ<sub>sym</sub>It can be seen that does not depend on the wavelength of light.
0134Now, consider the two cases shown in FIGS. 9 (A) and 9 (B) as simple examples. First, in the case of FIG. 9A, the optical axis of the head 64 is aligned with the Z-axis direction (the head 64 is not tilted). Here, it is assumed that the wafer stage WST is displaced in the Z-axis direction (ΔZ 0, ΔY = 0). In this case, since there is no change in the optical path difference ΔL, there is no change in the first term on the right side of Eq. (7). The second term becomes zero from the assumption ΔY = 0. Then, the third term satisfies the symmetry of Eq. (8), so that it becomes zero. Therefore, the phase difference φ does not change, and the intensity of the interference light does not change. As a result, the measured value (count value) of the encoder does not change either.
0135On the other hand, in the case of FIG. 9B, the optical axis of the head 64 is tilted with respect to the Z axis (the head 64 is tilted). From this state, it is assumed that the wafer stage WST is displaced in the Z-axis direction (ΔZ 0, ΔY = 0). In this case as well, there is no change in the optical path difference ΔL, so there is no change in the first term on the right side of Eq. (7). And the second term becomes zero from the assumption ΔY = 0. However, since the symmetry of Eq. (8) is broken by tilting the head, the third term does not become zero and changes in proportion to the Z displacement ΔZ. Therefore, the phase difference φ changes, and as a result, the measured value changes. Even if the head 64 is not tilted, the symmetry of the equation (8) is broken depending on the optical characteristics (telecentricity, etc.) of the head, and the measured value changes in the same manner. That is, the characteristic information of the head unit, which causes a measurement error of the encoder system, includes not only the tilt of the head but also its optical characteristics.
0136Although not shown, when the displacement is perpendicular to the measurement direction (Y-axis direction) and the optical axis direction (Z-axis direction) (ΔX 0, ΔY = 0, ΔZ = 0), the diffraction grid RG As long as the direction (longitudinal direction) of the grid lines is orthogonal to the measurement direction, the measured value does not change, but if it is not orthogonal, sensitivity is generated with a gain proportional to the angle.
0137Next, consider, for example, the four cases shown in FIGS. 10 (A) to 10 (D). First, in the case of FIG. 10A, the optical axis of the head 64 coincides with the Z-axis direction (the head 64 is not tilted). Even if the wafer stage WST moves in the + Z direction from this state to the state shown in FIG. 10 (B), the measured value of the encoder does not change because the case is the same as in FIG. 9 (A) above.
0138Next, it is assumed that the wafer stage WST rotates about the X-axis from the state shown in FIG. 10 (B) to the state shown in FIG. 10 (C). In this case, even though the head and the scale do not move relative to each other, that is, ΔY = ΔZ = 0, the optical path difference ΔL changes due to the rotation of the wafer stage WST, so that the measured value of the encoder changes. That is, a measurement error occurs in the encoder system due to the tilt of the wafer stage WST.
0139Next, it is assumed that the wafer stage WST moves downward from the state shown in FIG. 10 (C) and becomes the state shown in FIG. 10 (D). In this case, since the wafer stage WST does not rotate, the optical path difference ΔL does not change. However, since the symmetry of Eq. (8) is broken, the phase difference φ changes due to the Z displacement ΔZ through the third term on the right side of Eq. (7). As a result, the measured value of the encoder changes. The measured value of the encoder in the case of FIG. 10 (D) is the same as that of FIG. 10 (A).
0140As a result of simulations conducted by the inventors, the measured values of the encoder are not only for changes in the scale position in the Y-axis direction, which is the measurement direction, but also for changes in attitude in the θx direction (pitching direction) and θz direction (yowing direction). In addition to having sensitivity, it was found that it also depends on the position change in the Z-axis direction when the above-mentioned symmetry is broken. That is, the above theoretical explanation and the result of the simulation agreed.
0141Therefore, in the present embodiment, the correction information for correcting the measurement error of each encoder due to the relative movement of the head and the scale in the non-measurement direction described above is acquired as follows.
0142First, the main controller 20 monitors the measured values of the Y interferometer 16, the X interferometer 126, and the Z interferometers 43A and 43B of the interferometer system 118, and performs the wafer stage WST via the stage drive system 124. Drive the Y head 64 on the most -X side of the head unit 62A, as shown in FIGS. 11 (A) and 11 (B), with the Y scale 39Y on the top surface of the wafer table WTB.<sub>1</sub>Arbitrary area of (the area circled in FIG. 11 (A)) facing AR.
0143b. Then, the main controller 20 sets the rolling amount θy and yawing amount θz of the wafer table WTB (wafer stage WST) to zero and the pitching amount based on the measured values of the Y interferometer 16 and the Z interferometers 43A and 43B. θx is the desired value α<sub>0</sub>(Here, α<sub>0</sub>= 200 μrad. ), The wafer table WTB (wafer stage WST) is driven, and after the drive, the head 64 to the Y scale 39Y<sub>1</sub>The area AR of is irradiated with the detection light, and the measured value corresponding to the photoelectric conversion signal from the head 64 that receives the reflected light is stored in the internal memory.
0144c. Next, the main controller 20 sets the attitude (pitching amount θx = α) of the wafer table WTB (wafer stage WST) based on the measured values of the Y interferometer 16 and the Z interferometers 43A and 43B.<sub>0</sub>, Yaw amount θz = 0, rolling amount θy = 0), as shown by the arrow in FIG. 11 (B), keep the wafer table WTB (wafer stage WST) within a predetermined range, for example, -100 μm to +. It is driven in the Z-axis direction within a range of 100 μm, and during the driving, the head 64 to Y scale 39Y<sub>1</sub>While irradiating the area AR with the detection light, the measured values corresponding to the photoelectric conversion signals from the head 64 that received the reflected light are sequentially taken in and stored in the internal memory at a predetermined sampling interval.
0145d. Next, the main controller 20 sets the pitching amount of the wafer table WTB (wafer stage WST) based on the measured value of the Y interferometer 16 (θx = α).<sub>0</sub>Change to -Δα).
0146e. Next, the same operation as in c. Above is repeated for the changed posture.
0147f. After that, the operations of d. And e are repeated alternately, and for a range in which the pitching amount θx is, for example, -200 μrad <θx <+ 200 μrad, Δα (rad), for example, a head within the Z drive range at intervals of 40 μrad. Capture 64 measurements.
0148g. Next, plot each data in the internal memory obtained by the above processes b. To e. On a two-dimensional coordinate system with the horizontal axis as the Z position and the vertical axis as the encoder measurement value, and the pitching amount. By sequentially connecting the plot points at the same time and shifting the horizontal axis with respect to the vertical axis so that the line with zero pitching amount (the horizontal line in the center) passes through the origin, as shown in FIG. , The graph is obtained.
0149The value on the vertical axis of each point on the graph of FIG. 12 is nothing but the measurement error of the encoder at each Z position in the pitching amount θx = α. Therefore, in the main controller 20, the pitching amount θx, Z position, and encoder measurement error of each point on the graph of FIG. 12 are used as table data, and the table data is stored in the memory 34 (see FIG. 6) as correction information. To do. Alternatively, the main controller 20 uses the measurement error as a function of the Z position z and the pitching amount θx, obtains the function by calculating an undetermined coefficient by, for example, the least squares method, and uses the function as correction information in the memory 34. Store.
0150h. Next, the main controller 20 drives the wafer stage WST in the -X direction by a predetermined amount via the stage drive system 124 while monitoring the measured value of the X interferometer 126 of the interferometer system 118, and Fig. 13 As shown in, the second Y head 64 from the -X side end of the head unit 62A (the Y head next to the Y head 64 for which data acquisition has been completed above) is placed on the Y scale 39Y on the upper surface of the wafer table WTB.<sub>1</sub>Facing the above-mentioned area AR (the area circled in FIG. 13).
0151i. Then, the main controller 20 performs the same processing as described above for the Y head 64, and the head 64 and the Y scale 39Y.<sub>1</sub>The correction information of the Y encoder 70A composed of and is stored in the memory 34.
0152j. In the same manner thereafter, each of the remaining Y heads 64 and Y scale 39Y of the head unit 62A<sub>1</sub>Correction information of Y encoder 70A composed of and, each X head 66 and X scale 39X of head unit 62B<sub>1</sub>Correction information of X encoder 70B composed of and, each X head 64 and Y scale 39Y of head unit 62C<sub>2</sub>Correction information of Y encoder 70C composed of, and each X head 66 and X scale 39X of head unit 62D<sub>2</sub>The correction information of the X encoder 70D composed of and is obtained and stored in the memory 34.
0153Here, in the above-mentioned measurement using each X head 66 of the head unit 62B, the X scale 39X is the same as described above.<sub>1</sub>In the above measurement using the same area above and using each Y head 64 of the head unit 62C, the Y scale 39Y<sub>2</sub>In the above measurement using the same area above and using each Y head 66 of the head unit 62D, the X scale 39X<sub>2</sub>It is important to use the same area above. The reason is that if the correction of each interferometer of the interferometer system 118 (including the bending correction of the reflecting surfaces 17a, 17b and the reflecting surfaces 41a, 41b, 41c) is completed, it is based on the measured value of those interferometers. The orientation of the wafer stage WST can be set to the desired orientation at any time, and by using the same part of each scale, even if the scale surface is inclined, it is affected by it and a measurement error occurs between each head. Because there is nothing.
0154The main controller 20 is a Y head 64y.<sub>1</sub>, 64y<sub>2</sub>About, the same Y scale 39Y as each Y head 64 of the above-mentioned head units 62C, 64A<sub>2</sub>, 39Y<sub>1</sub>Perform the above measurements using each of the same areas above, Y scale 39Y<sub>2</sub>Y head 64y facing<sub>1</sub>(Encoder 70C) correction information and Y scale 39Y<sub>1</sub>Y head 64y facing<sub>2</sub>The correction information of (encoder 70A) is obtained and stored in the memory 34.
0155Next, in the main controller 20, the yawing amount θz of the wafer stage WST is set to-while maintaining both the pitching amount and the rolling amount of the wafer stage WST at zero in the same procedure as when the pitching amount is changed as described above. The wafer table WTB (wafer stage WST) is driven in a predetermined range, for example, in the range of -100 μm to + 100 μm in the Z-axis direction by sequentially changing the range of 200 μrad <θz <+ 200 μrad, and is being driven. The measured values of the heads are sequentially fetched and stored in the internal memory at predetermined sampling intervals. Such measurement is performed for all heads 64 or 66, and each data in the internal memory is plotted on two-dimensional coordinates with the horizontal axis as the Z position and the vertical axis as the encoder measurement value in the same procedure as described above. Then, plot points with the same yawing amount are connected in sequence, and the horizontal axis is shifted so that the line with zero yawing amount (the horizontal line in the center) passes through the origin. To get. Then, the main control device 20 uses the yawing amount θz, Z position, and measurement error of each point on the obtained graph as table data, and stores the table data in the memory 34 as correction information. Alternatively, the main controller 20 uses the measurement error as a function of the Z position z and the yawing amount θz, obtains the function by calculating an undetermined coefficient by, for example, the least squares method, and uses the function as correction information in the memory 34. Store.
0156Here, when the pitching amount of the wafer stage WST is not zero and the yawing amount is not zero, the measurement error of each encoder at the Z position z of the wafer stage WST is the above-mentioned at the Z position z. It can be considered as a simple sum (linear sum) of the measurement error according to the pitching amount and the measurement error according to the yawing amount. The reason is that, as a result of the simulation, it has been confirmed that the measurement error (count value (measured value)) changes linearly according to the change in the Z position even when the yawing is changed.
0157In the following, for the sake of brevity, the pitching amount θx, yawing amount θz, and Z position z of the wafer stage WST representing the measurement error Δy as shown by the following equation (10) for the Y head of each Y encoder. It is assumed that the function of is obtained and stored in the memory 34. Further, for the X head of each X encoder, the functions of the rolling amount θy, yawing amount θz, and Z position z of the wafer stage WST representing the measurement error Δx as shown in the following equation (11) are obtained, and the memory 34 It is assumed that it is stored in.
0158Δy = f (z, θx, θz) = θx (za) + θz (zb) ...... (10) Δx = g (z, θy, θz) = θy (zc) + θz (zd) ...... (11) In the above equation (10), a is the Z coordinate of the point where each straight line intersects in the graph of FIG. 12, and b is FIG. 12 when the yawing amount is changed to acquire the correction information of the Y encoder. It is the Z coordinate of the point where each straight line intersects in the same graph as. Further, in the above equation (11), c is the Z coordinate of the point where each straight line intersects in the same graph as in FIG. 12 when the rolling amount is changed to acquire the correction information of the X encoder, and d. Is the Z coordinate of the point where each straight line intersects in the same graph as in FIG. 12 when the yawing amount is changed to acquire the correction information of the X encoder.
0159Next, the parallel processing operation using the wafer stage WST and the measurement stage MST in the exposure apparatus 100 of the present embodiment will be described with reference to FIGS. 14 to 27. During the following operation, the main control device 20 controls the opening and closing of each valve of the liquid supply device 5 and the liquid recovery device 6 of the local immersion device 8 as described above, and the tip lens of the projection optical system PL. The injection surface side of 191 is always filled with water. However, in the following, for the sake of clarity, the description regarding the control of the liquid supply device 5 and the liquid recovery device 6 will be omitted. In addition, although the subsequent operation description will be given using a large number of drawings, the same member may or may not be designated for each drawing. That is, although the reference numerals described are different for each drawing, those drawings have the same configuration regardless of the presence or absence of the reference numerals. The same applies to each drawing used in the explanation so far.
0160In FIG. 14, a step-and-scan exposure is performed on a wafer W on a wafer stage WST (here, as an example, an intermediate wafer of a lot (1 lot is 25 or 50 wafers)). The state is shown. At this time, the measurement stage MST may stand by at a retracted position where collision with the wafer stage WST is avoided, but in the present embodiment, the measurement stage MST follows and moves while maintaining a predetermined distance from the wafer stage WST. .. Therefore, the moving distance of the measurement stage MST when shifting to the contact state (or proximity state) with the wafer stage WST after the end of exposure is sufficient to be the same as the above-mentioned predetermined distance.
0161During this exposure, the main controller 20 allows the X scale 39X<sub>1</sub>, 39X<sub>2</sub>Two X-heads 66 (X-encoders 70B, 70D) and Y-scale 39Y, respectively, circled in Figure 14 facing each other.<sub>1</sub>, 39Y<sub>2</sub>Of the two Y heads 64 (Y encoders 70A, 70C) circled in FIG. 14 facing each other, at least three encoder measurements and wafers measured by the interferometer system 118. Based on the pitching amount or rolling amount and yawing amount of the stage WST, and the correction information of each encoder stored in the memory 34 according to the Z position (correction information obtained by the above-mentioned equation (10) or equation (11)). Therefore, the position (including θz rotation) of the wafer table WTB (wafer stage WST) in the XY plane is controlled. Further, by the main controller 20, the position of the wafer table WTB in the Z-axis direction and the θy rotation (rolling) and the θx rotation (pitching) are the ends of the wafer table WTB surface on one side and the other side in the X-axis direction (this). In the embodiment, Y scale 39Y<sub>1</sub>, 39Y<sub>2</sub>) Each pair of Z sensors 74<sub>1,j</sub>,74<sub>2,j</sub>、76<sub>1,q</sub>,76<sub>2,q</sub>It is controlled based on the measured value of. The position of the wafer table WTB in the Z-axis direction and the θy rotation (rolling) are determined by the Z sensor 74.<sub>1,j</sub>,74<sub>2,j</sub>、76<sub>1,q</sub>,76<sub>2,q</sub>It may be controlled based on the measured value of, and the θx rotation (pitching) may be controlled based on the measured value of the Y interferometer 16. In any case, the control of the position, θy rotation and θx rotation of the wafer table WTB during this exposure in the Z-axis direction (focus leveling control of the wafer W) is performed in advance by the above-mentioned multipoint AF system. It is done based on the result of mapping.
0162The above exposure operation is the result of wafer alignment (for example, enhanced global alignment (EGA)) performed in advance by the main controller 20, and the alignment systems AL1 and AL2.<sub>1</sub>~ AL2<sub>4</sub>The inter-shot movement operation in which the wafer stage WST is moved to the scanning start position (acceleration start position) for exposure of each shot area on the wafer W based on the latest baseline, etc., and the reticle for each shot area. It is performed by repeating the scanning exposure operation of transferring the pattern formed in R by the scanning exposure method. The above exposure operation is performed with water held between the tip lens 191 and the wafer W. Further, the exposure is performed in the order of the shot region located on the -Y side to the shot region located on the + Y side in FIG. The EGA method is disclosed in, for example, US Pat. No. 4,780,617.
0163Then, the main controller 20 maintains the measured value of the X interferometer 130 at a constant value before the final shot region on the wafer W is exposed, and the stage drive system is based on the measured value of the Y interferometer 18. Control 124 to move the measurement stage MST (measurement table MTB) to the position shown in FIG. At this time, the end face on the -Y side of the CD bar 46 (measurement table MTB) and the end face on the + Y side of the wafer table WTB are in contact with each other. For example, the measurement value of the interferometer or encoder that measures the position of each table in the Y-axis direction is monitored, and the measurement table MTB and the wafer table WTB are separated by about 300 μm in the Y-axis direction so that they are in a non-contact state (proximity state). ) May be kept. The wafer stage WST and the measurement stage MST are set to the positional relationship shown in FIG. 15 during the exposure of the wafer W, and then moved so as to maintain this positional relationship.
0164Next, as shown in FIG. 16, the main controller 20 starts the operation of driving the measurement stage MST in the -Y direction while maintaining the positional relationship between the wafer table WTB and the measurement table MTB in the Y-axis direction. , Start the operation of driving the wafer stage WST toward the unloading position UP. When this operation is started, in the present embodiment, the measurement stage MST is moved only in the -Y direction, and the wafer stage WST is moved in the -Y direction and the -X direction.
0165In this way, when the wafer stage WST and the measurement stage MST are simultaneously driven by the main controller 20, the water held between the tip lens 191 of the projection unit PU and the wafer W (shown in FIG. 16). The water in the immersion region 14) moves sequentially on the wafer W plate 28 CD bar 46 measurement table MTB as the wafer stage WST and the measurement stage MST move to the -Y side. During the above movement, the wafer table WTB and the measurement table MTB maintain the above-mentioned contact state (or proximity state). Note that FIG. 16 shows a state immediately before the water in the immersion region 14 is passed from the plate 28 to the CD bar 46. Further, in the state shown in FIG. 16, the measured values of the three encoders 70A, 70B, and 70D by the main controller 20 (and the pitching amount or rolling amount and yawing amount of the wafer stage WST measured by the interferometer system 118). , And the position (including θz rotation) of the wafer table WTB (wafer stage WST) in the XY plane is controlled based on the encoder 70A, 70B or 70D correction information stored in the memory 34 according to the Z position. Has been done.
0166If the wafer stage WST and the measurement stage MST are slightly driven in the above directions at the same time from the state shown in FIG. 16, the position of the wafer stage WST (wafer table WTB) cannot be measured by the Y encoder 70A (and 70C). Therefore, immediately before this, the main controller 20 controls the Y position and θz rotation of the wafer stage WST (wafer table WTB) from the control based on the measured values of the Y encoders 70A and 70C to the Y interferometer 16 and Z interferometer. Switch to control based on the measured values of 43A and 43B in total. Then, after a predetermined time, as shown in FIG. 17, the measurement stage MST performs the baseline measurement of the secondary alignment system performed at a predetermined interval (here, every wafer exchange) (hereinafter, also referred to as Sec-BCHK (interval) as appropriate). Reach the position to call). Then, the main controller 20 stops the measurement stage MST at that position and X scale 39X.<sub>1</sub>The X position of the wafer stage WST is measured by the X head 66 (X linear encoder 70B) circled in FIG. 17 facing the wafer stage, and the Y-axis direction and θz rotation are measured by the Y interferometer 16 and the Z interferometer 43A. While measuring with 43B, the wafer stage WST is further driven toward the unloading position UP and stopped at the unloading position UP. In the state of FIG. 17, water is held between the measurement table MTB and the tip lens 191.
0167The main controller 20 is then shown circled in FIG. 18 facing the pair of reference grids 52 on the CD bar 46 supported by the measurement stage MST, respectively, as shown in FIGS. 17 and 18. Y head 64y<sub>1</sub>, 64y<sub>2</sub>Based on the measured values of the Y-axis linear encoders 70E and 70F configured by, the θz rotation of the CD bar 46 is adjusted, and the reference mark M located on or near the center line CL of the measurement table MTB is detected. Adjust the XY position of the CD bar 46 based on the measured value of the primary alignment system AL1 shown in the circle in Fig. 18. Then, in this state, the main controller 20 has four secondary alignment systems AL2.<sub>1</sub>~ AL2<sub>4</sub>By simultaneously measuring the reference mark M on the CD bar 46 in the field of view of each secondary alignment system, the four secondary alignment systems AL2<sub>1</sub>~ AL2<sub>4</sub>Sec-BCHK (interval) is performed to obtain the baseline (relative positions of the four secondary alignment systems with respect to the primary alignment system AL1). In parallel with this Sec-BCHK (interval), the main controller 20 gives a command to the drive system of the unload arm (not shown) for the wafer W on the wafer stage WST stopped at the unloading position UP. While unloading, the wafer stage WST is driven in the + X direction to the loading position while the vertical movement pin CT (not shown in Fig. 17, see Fig. 18) that was driven up during the unloading is raised by a predetermined amount. Move to LP.
0168Next, the main controller 20 for shifting the measurement stage MST from the state separated from the wafer stage WST to the above-mentioned contact state (or close state) with the wafer stage WST, as shown in FIG. Move to the optimum standby position (hereinafter referred to as "optimal scrum standby position"). In parallel with this, the main controller 20 gives a command to the drive system of the load arm (not shown) to load a new wafer W on the wafer table WTB. In this case, since the vertical movement pin CT is maintained in a state of being raised by a predetermined amount, the wafer can be loaded in a shorter time than when the vertical movement pin CT is driven downward and stored inside the wafer holder. .. Note that FIG. 19 shows a state in which the wafer W is loaded on the wafer table WTB.
0169In the present embodiment, the optimum scrum standby position of the measurement stage MST described above is appropriately set according to the Y coordinate of the alignment mark attached to the alignment shot region on the wafer. Further, in the present embodiment, the optimum scrum standby position is determined so that the wafer stage WST can shift to the contact state (or the proximity state) at the position where the wafer stage WST stops for wafer alignment.
0170Next, as shown in FIG. 20, the main controller 20 positions the wafer stage WST from the loading position LP with the reference mark FM on the measurement plate 30 within the field of view (detection region) of the primary alignment system AL1. Move to the position (that is, the position where the first half of the baseline measurement (Pri-BCHK) of the primary alignment system is performed). During this movement, the main controller 20 controls the position of the wafer table WTB in the XY plane with the encoder 70B in the X-axis direction and the Y interferometer 16 and Z interferometer in the Y-axis direction and θz rotation. From control based on measured values of 43A and 43B, X scale 39X<sub>1</sub>, 39X<sub>2</sub>At least one of the two X heads 66 (encoders 70B, 70D) circled in Figure 20 facing the Y scale 39Y<sub>1</sub>, 39Y<sub>2</sub>Two Y-heads 64y circled in Figure 20 facing<sub>2</sub>, 64y<sub>1</sub>It is stored in the memory 34 according to the measured values of at least three encoders (encoders 70A and 70C), the pitching amount or rolling amount and yawing amount of the wafer stage WST measured by the interferometer system 118, and the Z position. Switch to control of the position in the XY plane based on the correction information of each encoder (correction information obtained by the above equations (10) and (11)).
0171Then, the main controller 20 performs the first half of the Pri-BCHK process of detecting the reference mark FM using the primary alignment system AL1. At this time, the measurement stage MST is waiting at the above-mentioned optimum scrum standby position.
0172Next, the main controller 20 detects the alignment marks attached to the three first alignment shot regions while managing the position of the wafer stage WST based on the measured values and correction information of at least three encoders described above. Start moving the wafer stage WST in the + Y direction toward the position.
0173Then, when the wafer stage WST reaches the position shown in FIG. 21, the main controller 20 stops the wafer stage WST. Prior to this, the main controller 20 activates (turns on) the Z sensors 72a to 72d at the time when the Z sensors 72a to 72d are hung on the wafer table WTB or at a time before the Z sensors 72a to 72d, and the wafer table WTB. The Z position and tilt (θy rotation and θx rotation) are measured.
0174After the wafer stage WST is stopped, the main controller 20 is subjected to the primary alignment system AL1 and the secondary alignment system AL2.<sub>2</sub>, AL2<sub>3</sub>The alignment marks attached to the three first alignment shot regions are detected almost simultaneously and individually (see the star mark in Fig. 21), and the above three alignment systems AL1 and AL2 are used.<sub>2</sub>, AL2<sub>3</sub>Is stored in the internal memory in association with the detection result of the above and the measurement values (measured values after correction by the correction information) of the above three encoders at the time of the detection.
0175As described above, in the present embodiment, the transition to the contact state (or proximity state) between the measurement stage MST and the wafer stage WST is completed at the position where the alignment mark in the first alignment shot region is detected, and from that position, The main controller 20 moves both stages WST and MST in the + Y direction in the contact state (or close state) (step toward the position where the alignment marks attached to the five second alignment shot areas are detected). Move) is started. Prior to the start of movement of both stages WST and MST in the + Y direction, the main controller 20 wafers the detection beam from the irradiation system 90a of the multipoint AF system (90a, 90b) as shown in FIG. Irradiation has started toward the table WTB. As a result, a detection region for the multipoint AF system is formed on the wafer table WTB.
0176Then, when both stages WST and MST reach the positions shown in FIG. 22 during the movement of both stages WST and MST in the + Y direction, the main controller 20 performs the first half of the focus calibration. , Measured values (wafer) of Z sensors 72a, 72b, 72c, 72d in a state where the straight line LV described above coincides with the straight line (center line) in the Y-axis direction passing through the center of the wafer table WTB (almost coincident with the center of the wafer W). Surface position information on one side and the other end of the table WTB in the X-axis direction) and detection points on the surface of the measurement plate 30 of the multipoint AF system (90a, 90b) (center or near the center of multiple detection points) The relationship with the detection result (plane position information) at the detection point located at) is obtained. At this time, the immersion region 14 is located near the boundary between the CD bar 46 and the wafer table WTB. That is, the immersion region 14 is in a state immediately before being passed from the CD bar 46 to the wafer table WTB.
0177Then, when both stages WST and MST move further in the + Y direction while maintaining the contact state (or close state) and reach the position shown in FIG. 23, the five alignment systems AL1 and AL2<sub>1</sub>~ AL2<sub>4</sub>The alignment marks attached to the five second alignment shot regions are detected almost simultaneously and individually (see the star mark in Fig. 23), and the above five alignment systems AL1 and AL2 are used.<sub>1</sub>~ AL2<sub>4</sub>The detection result of is associated with the measured values of the three encoders 70A, 70C, and 70D at the time of the detection (measured values after correction by the correction information) and stored in the internal memory. At this time, X scale 39X<sub>1</sub>Since there is no X head located on a straight line LV in the Y-axis direction that faces the optical axis of the projection optical system PL and passes through the optical axis of the projection optical system PL, the main controller 20 is an X scale 39X.<sub>2</sub>The position of the wafer table WTB in the XY plane is controlled based on the measured values of the X head 66 (X linear encoder 70D) and the Y linear encoders 70A and 70C facing the same.
0178As described above, in the present embodiment, when the detection of the alignment mark in the second alignment shot region is completed, the position information (two-dimensional position information) of the alignment marks of a total of eight points can be detected. Therefore, at this stage, the main control device 20 performs statistical calculations disclosed in, for example, Japanese Patent Application Laid-Open No. 61-44429 (corresponding US Pat. No. 4,780,617) using these position information. The scaling (shot magnification) of the wafer W may be obtained, and the adjustment device 68 (see FIG. 6) may be controlled based on the calculated shot magnification to adjust the optical characteristics of the projection optical system PL, for example, the projection magnification. .. The adjusting device 68 drives, for example, a specific movable lens constituting the projection optical system PL, or changes the pressure of the gas in the airtight chamber formed between the specific lenses constituting the projection optical system PL. , Adjust the optical characteristics of the projection optical system PL.
0179In addition, the main controller 20 moves the WST and MST in both stages in the + Y direction in the contact state (or close state) after the simultaneous detection of the alignment marks attached to the above five second alignment shot areas is completed. At the same time as starting again, focus mapping using the Z sensors 72a to 72d and the multipoint AF system (90a, 90b) at the same time is started as shown in FIG.
0180Then, when both stages WST and MST reach the position where the measurement plate 30 shown in FIG. 24 is arranged directly under the projection optical system PL, the main controller 20 performs the processing in the latter half of the Pri-BCHK and the latter half of the focus calibration. Is processed. Here, in the processing of the latter half of Pri-BCHK, a projection image (spatial image) of a pair of measurement marks on the reticle R projected by the projection optical system PL is formed on the measurement plate 30 with a spatial image measurement slit pattern SL. This refers to the process of measuring using the above-mentioned spatial image measuring device 45 and storing the measurement result (spatial image intensity according to the XY position of the wafer table WTB) in the internal memory. In this process, a pair of spatial image measurement operations of the slit scan method using the pair of spatial image measurement slit patterns SL are performed in the same manner as the method disclosed in the above-mentioned US Patent Application Publication No. 2002/0041377. The projected image of the measurement mark is measured. Further, the processing in the latter half of the focus calibration means that the main controller 20 measures the surface position information of the wafer table WTB (wafer stage WST) measured by the Z sensors 72a, 72b, 72c, 72d as shown in FIG. 24. While controlling the position (Z position) of the projection optical system PL of the measurement plate 30 (wafer table WTB) with respect to the optical axis direction based on the above, the spatial image measuring device 45 is used to display the reticle R or the reticle stage RST. This refers to the process of measuring the spatial image of the measurement mark formed on the illustrated mark plate and measuring the best focus position of the projection optical system PL based on the measurement result. The measurement operation of the projected image of this measurement mark is disclosed in, for example, International Publication No. 05/124834. The main control device 20 moves the measurement plate 30 in the Z-axis direction, and synchronizes with the acquisition of the output signal from the spatial image measurement device 45, and the Z sensor 74.<sub>1,4</sub>,74<sub>2,4</sub>、76<sub>1,3</sub>、76<sub>2,3</sub>Capture the measured value of. And the Z sensor 74 corresponding to the best focus position of the projection optical system PL<sub>1,4</sub>,74<sub>2,4</sub>、76<sub>1,3</sub>、76<sub>2,3</sub>The value of is stored in a memory (not shown). In the latter half of the focus calibration, the position of the measurement plate 30 (wafer stage WST) with respect to the optical axis direction is used by using the surface position information measured by the Z sensors 72a, 72b, 72c, and 72d. The (Z position) is controlled because the latter half of the focus calibration is performed in the middle of the focus mapping described above.
0181In this case, since the immersion region 14 is formed between the projection optical system PL and the measurement plate 30 (wafer table WTB), the above spatial image measurement is performed via the projection optical system PL and water Lq. Be struck. Further, since the measurement plate 30 and the like are mounted on the wafer stage WST (wafer table WTB) and the light receiving element and the like are mounted on the measurement stage MST, the above spatial image measurement is performed on the wafer as shown in FIG. The stage WST and the measurement stage MST are performed while maintaining the contact state (or proximity state). Based on the above measurement, the Z sensor 74 in a state where the straight line LV corresponding to the best focus position of the projection optical system PL coincides with the straight line (center line) in the Y-axis direction passing through the center of the wafer table WTB.<sub>1,4</sub>,74<sub>2,4</sub>、76<sub>1,3</sub>、76<sub>2,3</sub>(That is, the surface position information of the wafer table WTB) can be obtained.
0182Then, the main controller 20 calculates the baseline of the primary alignment system AL1 based on the result of the first half of the Pri-BCHK and the result of the second half of the Pri-BCHK. At the same time, the main controller 20 uses the measured values (plane position information of the wafer table WTB) of the Z sensors 72a, 72b, 72c, 72d obtained in the first half of the focus calibration described above and the multipoint AF system (90a). , 90b) Z sensor 74 corresponding to the relationship between the detection result (plane position information) at the detection point on the surface of the measurement plate 30 and the best focus position of the projection optical system PL obtained in the latter half of the focus calibration described above.<sub>1,4</sub>,74<sub>2,4</sub>、76<sub>1,3</sub>、76<sub>2,3</sub>Based on the measured value of (that is, the plane position information of the wafer table WTB), a typical detection point (in this case, a plurality of detection points) of the multipoint AF system (90a, 90b) with respect to the best focus position of the projection optical system PL. The offset at the detection point located at or near the center of the points) is obtained, and the detection origin of the multipoint AF system is adjusted so that the offset becomes zero, for example, by an optical method.
0183In this case, from the viewpoint of improving the throughput, only one of the above-mentioned Pri-BCHK second half processing and the focus calibration second half processing may be performed, or the next processing may be performed without performing both processing. You may move to. Of course, when the latter half of the Pri-BCHK is not processed, it is not necessary to perform the first half of the Pri-BCHK. In this case, the main controller 20 is first aligned from the loading position LP described above. The wafer stage WST may be moved to a position where the alignment mark attached to the shot area is detected. When the Pri-BCHK process is not performed, the baseline measured by the same operation immediately before the exposure of the wafer before the wafer W to be exposed is used. If the latter half of the focus calibration is not performed, the best focus position of the projection optical system PL measured immediately before the exposure of the previous wafer is used as in the baseline.
0184In the state of FIG. 24, the above-mentioned focus calibration is continued.
0185When the wafer stage WST reaches the position shown in FIG. 25 after a predetermined time due to the movement of both stages WST and MST in the + Y direction in the above contact state (or close state), the main controller 20 is moved. The wafer stage WST is stopped at that position, and the measurement stage MST continues to move in the + Y direction. The main controller 20 is composed of five alignment systems AL1 and AL2.<sub>1</sub>~ AL2<sub>4</sub>The alignment marks attached to the five third alignment shot regions are detected almost simultaneously and individually (see the star mark in FIG. 25), and the above five alignment systems AL1 and AL2 are used.<sub>1</sub>~ AL2<sub>4</sub>Is stored in the internal memory in association with the detection result of at least three encoders (measured values after correction by the correction information) among the above four encoders at the time of the detection. At this time, focus mapping is continuing.
0186On the other hand, after a predetermined time from the stop of the wafer stage WST, the measurement stage MST and the wafer stage WST shift from the contact (or close state) to the separated state. After shifting to this separated state, when the measurement stage MST reaches the exposure start standby position that waits until the start of exposure, the main control device 20 stops at that position.
0187Next, the main controller 20 starts moving the wafer stage WST in the + Y direction toward the position where the alignment marks attached to the three force alignment shot regions are detected. At this time, focus mapping is continuing. On the other hand, the measurement stage MST stands by at the exposure start standby position.
0188Then, when the wafer stage WST reaches the position shown in FIG. 26, the main controller 20 immediately stops the wafer stage WST, and the primary alignment system AL1 and the secondary alignment system AL2<sub>2</sub>, AL2<sub>3</sub>The alignment marks attached to the three force alignment shot regions on the wafer W are detected almost simultaneously and individually (see the star marks in FIG. 26), and the above three alignment systems AL1 and AL2 are used.<sub>2</sub>, AL2<sub>3</sub>Is stored in the internal memory in association with the detection result of at least three encoders (measured values after correction by the correction information) among the above four encoders at the time of the detection. Even at this point, the focus mapping is continued, and the measurement stage MST remains on standby at the exposure start standby position. Then, the main controller 20 uses, for example, US Pat. No. 4,780,617, using the detection results of a total of 16 alignment marks obtained in this way and the measured values of the corresponding encoders (measured values after correction based on the correction information). All shot areas on the wafer W on the coordinate system (for example, the XY coordinate system with the center of the wafer table WTB as the origin) defined by the measurement axes of the above four encoders by the EGA method disclosed in the specification etc. Calculate the array information (coordinate values) of.
0189Next, the main controller 20 continues the focus mapping while moving the wafer stage WST in the + Y direction again. Then, when the detection beam from the multipoint AF system (90a, 90b) deviates from the surface of the wafer W, focus mapping ends as shown in FIG. 27. After that, the main controller 20 uses the results of the above-mentioned wafer alignment (EGA) performed in advance and the latest five alignment systems AL1 and AL2.<sub>1</sub>~ AL2<sub>4</sub>The step-and-scan method of exposure is performed by immersion exposure based on the baseline of the above, and the reticle pattern is sequentially transferred to a plurality of shot regions on the wafer W. After that, the same operation is repeated in order to expose the remaining wafers in the lot.
0190Up to now, in order to simplify the explanation, the main control device 20 has been assumed to control each component of the exposure device such as the stage system, but the above-mentioned main control device 20 is not limited to this. Of course, at least a part of the control to be performed may be shared by a plurality of control devices. For example, a stage control device that controls the wafer stage WST or the like based on the measured values of the encoder system, the Z sensor, and the interferometer system may be provided under the main control device 20. Further, the control performed by the main control device 20 does not necessarily have to be realized by hardware, and the computer that regulates the operation of the main control device 20 or some control devices that are shared and controlled as described above. It may be realized by a program as software.
0191As described in detail above, according to the exposure apparatus 100 of the present embodiment, when the wafer stage WST is moved in a predetermined direction, for example, in the Y-axis direction at the time of wafer alignment or exposure, the measurement information of the encoder system and the measurement information of the encoder system are used. The wafer stage WST is driven in the Y-axis direction based on position information (including tilt information, for example, rotation information in the θx direction) different from the Y-axis direction of the wafer stage WST. That is, the wafer stage WST is driven so as to compensate for the measurement error of the encoder system (encoder 70A, 70C) caused by the displacement (including inclination) of the wafer stage WST in a direction different from the Y-axis direction. In the present embodiment, the measured values of the encoders 70A and 70C for measuring the position information in the Y-axis direction of the wafer stage WST by the main controller 20 and the direction different from the Y-axis direction of the wafer stage WST at the time of the measurement (non-). Position information (measurement direction), for example, correction information (correction information according to the position information in the θx direction, θz direction, and Z-axis direction of the wafer stage WST measured by the Y interferometer 16 of the interferometer system 118 and the Z interferometers 43A and 43B. The wafer stage WST is driven in the Y-axis direction based on the correction information) calculated by the above equation (10). In this way, the head 64 and scale 39Y in the non-measurement direction<sub>1</sub>Or 39Y<sub>2</sub>The stage drive system 124 is controlled and the wafer stage WST is driven in the Y-axis direction based on the measured values of the encoders 70A and 70C whose measurement errors of the encoders 70A and 70C caused by the relative displacement of the are corrected by the correction information. ..
0192When moving the wafer stage WST in the X-axis direction, the measurement information of the encoder system and the position information (including tilt information, for example, rotation information in the θy direction) of the wafer stage WST in a direction different from the X-axis direction are used. Based on this, the wafer stage WST is driven in the X-axis direction. That is, the wafer stage WST is driven so as to compensate for the measurement error of the encoder system (encoder 70B, 70D) caused by the displacement (including inclination) of the wafer stage WST in a direction different from the X-axis direction. In the present embodiment, the measured values of the encoders 70B and 70D for measuring the position information of the wafer stage WST in the X-axis direction by the main controller 20 and the direction different from the X-axis direction of the wafer stage WST at the time of the measurement (non-). Position information in the measurement direction), for example, correction information according to the position information in the θy direction, θz direction, and Z-axis direction of the wafer stage WST measured by the Z interferometers 43A and 43B of the interferometer system 118 (the above-mentioned equation (11). The wafer stage WST is driven in the X-axis direction based on the correction information) calculated in). Therefore, it is possible to drive the wafer stage WST in a desired direction with high accuracy without being affected by the relative motion between the head and the scale other than the desired direction (measurement direction).
0193Further, according to the exposure apparatus 100 of the present embodiment, it is mainly due to the relative movement of the illumination light IL and the wafer W that are applied to the wafer W from the illumination system 10 via the reticle R, the projection optical system PL, and the water Lq. The control device 20 accurately drives the wafer stage WST on which the wafer W is placed based on the above-mentioned measured value of the encoder and the position information of the wafer stage in the non-measurement direction at the time of the measurement. Therefore, the reticle R pattern can be accurately formed on the wafer by scanning exposure and immersion exposure.
0194Further, according to the present embodiment, the main control device 20 changes the wafer stage WST to a plurality of different postures when acquiring the correction information of the measured values of the encoder described above, and the measurement results of the interferometer system 118 are obtained for each posture. Scale 39Y from encoder head 64 or 66 while maintaining the attitude of wafer stage WST based on<sub>1</sub>, 39Y<sub>2</sub>, 39X<sub>1</sub>Or 39X<sub>2</sub>The wafer stage WST is moved in a predetermined stroke range in the Z-axis direction while irradiating the specific region of the above with the detection light, and the measurement result of the encoder is sampled during the movement. As a result, the change information of the encoder measurement value (for example, the characteristic curve as shown in the graph of FIG. 12) according to the position in the direction orthogonal to the moving surface of the wafer stage WST (Z-axis direction) for each posture is obtained. can get.
0195Then, the main controller 20 performs a predetermined calculation based on the sampling result, that is, the change information of the measured value of the encoder according to the position of the wafer stage WST in the Z-axis direction for each posture, thereby performing the wafer. Obtain the correction information of the encoder measurement value according to the position information of the stage WST in the non-measurement direction. Therefore, it is possible to determine the correction information for correcting the measurement error of the encoder due to the relative change of the head and the scale with respect to the non-measurement direction by a simple method.
0196Further, in the present embodiment, when the above correction information is determined for a plurality of heads constituting the same head unit, for example, a plurality of Y heads 64 constituting the head unit 62A, the corresponding Y scale 39Y<sub>1</sub>The same specific area of the above is irradiated with the detection light from each Y head 64, the measurement result of the encoder described above is sampled, and based on the sampling result, each Y head 64 and the Y scale 39Y<sub>1</sub>Since the correction information of each encoder composed of and is determined, as a result, by using this correction information, the geometric error caused by the tilting of the head is also corrected. In other words, the main controller 20 targets a plurality of encoders corresponding to the same scale, and when obtaining the correction information, the head of the encoder that is the target when the wafer stage WST is moved in the Z-axis direction. The correction information of the target encoder is obtained in consideration of the geometrical error caused by the tilt. Therefore, in the present embodiment, the cosine error due to the different tilt angles of the plurality of heads does not occur. Further, even if the Y head 64 is not tilted, if a measurement error occurs in the encoder due to, for example, the optical characteristics (telecentricity, etc.) of the head, the measurement error can be obtained by similarly obtaining the correction information. It is possible to prevent the occurrence of the problem and the deterioration of the position control accuracy of the wafer stage WST. That is, in the present embodiment, the wafer stage WST is driven so as to compensate for the measurement error (hereinafter, also referred to as head-induced error) of the encoder system caused by the head unit. It should be noted that, for example, the correction information of the measured value of the encoder system may be calculated based on the characteristic information of the head unit (including, for example, the tilting of the head and / or the optical characteristics). Further, in the present embodiment, the above-mentioned stage position-induced error and the above-mentioned head-induced error may be corrected independently.
0197It should be noted that the configuration and arrangement of the encoder system, the interferometer system, the multipoint AF system, the Z sensor, and the like in the above embodiment are examples, and it goes without saying that the present invention is not limited thereto. For example, in the above embodiment, a pair of Y scales 39Y used for measuring the position in the Y-axis direction.<sub>1</sub>, 39Y<sub>2</sub>And a pair of X scales 39X used to measure the position in the X-axis direction<sub>1</sub>, 39X<sub>2</sub>And are provided on the wafer table WTB, and correspondingly, a pair of head units 62A and 62C are arranged on one side and the other side of the projection optical system PL in the X-axis direction, and the pair of head units 62B and 62D are provided. Illustrated the case where is arranged on one side and the other side of the projection optical system PL in the Y-axis direction. However, not limited to this, the Y scale 39Y for measuring the position in the Y-axis direction<sub>1</sub>, 39Y<sub>2</sub>And X scale 39X for X-axis position measurement<sub>1</sub>, 39X<sub>2</sub>At least one of them may be provided on the wafer table WTB instead of a pair, or at least one of the pair of head units 62A and 62C and the pair of head units 62B and 62D may be provided. Only one may be provided. Further, the extension direction of the scale and the extension direction of the head unit are not limited to orthogonal directions such as the X-axis direction and the Y-axis direction of the above-described embodiment, and may be directions that intersect each other. Further, the periodic direction of the diffraction grating may be a direction orthogonal to (or intersecting with) the longitudinal direction of each scale, and in this case, a plurality of head units corresponding to the direction orthogonal to the periodic direction of the diffraction grating. It suffices if the head of is arranged. Further, each head unit may have a plurality of heads arranged without a gap in a direction orthogonal to the periodic direction of the diffraction grating.
0198Further, in the above embodiment, a lattice portion (X scale, Y scale) is provided on the wafer table (wafer stage), and a head unit (X head, Y head) is arranged outside the wafer stage so as to face the lattice portion (X scale, Y scale). The case where the above-mentioned encoder system is adopted has been illustrated, but the present invention is not limited to this. ) May be arranged. In this case, when the Z sensor is also arranged on the upper surface of the wafer stage, the two-dimensional lattice (or the two-dimensionally arranged one-dimensional lattice portion) is also used as a reflecting surface for reflecting the measurement beam from the Z sensor. You may. Even when an encoder system having such a configuration is adopted, basically, the measurement error of the encoder due to the relative displacement of the head and the scale in the non-measurement direction is corrected by the same procedure as in the above embodiment. The wafer stage WST can be driven based on the informationally corrected encoder measurements. This makes it possible to drive the wafer stage WST in a desired direction with high accuracy without being affected by the relative motion between the head and the scale other than the desired direction (measurement direction). Further, the correction information for correcting the measurement error of the encoder due to the relative change of the head and the scale with respect to the non-measurement direction can be determined by the same simple method as that of the above embodiment.
0199In the above embodiment, the rotation information (pitching amount) of the wafer stage WST in the θx direction is measured by the interferometer system 118. For example, a pair of Z sensors 74<sub>i, j</sub>Or 76<sub>p, q</sub>The pitching amount may be obtained from the measured value of. Alternatively, similarly to the head units 62A and 62C, for example, one or a pair of Z sensors are provided in close proximity to each head of the head units 62B and 62D, and the X scale 39X<sub>1</sub>, 39X<sub>2</sub>The pitching amount may be obtained from the measured values of the Z sensors facing each other. This allows the wafer stage WST to have 6 degrees of freedom in the X-axis, Y-axis, Z-axis, θx, θy, and θz directions using the encoder and Z sensor described above without using the interferometer system 118. It becomes possible to measure the position information. The measurement of the position information in the direction of 6 degrees of freedom of the wafer stage WST by the encoder and the Z sensor described above may be performed not only by the exposure operation but also by the alignment operation and / or the focus mapping operation described above.
0200Further, in the above embodiment, the measurement error of the encoder system caused by the displacement (relative displacement between the head and the scale) of the wafer stage WST in a direction different from the predetermined direction for driving the wafer stage WST is compensated. The measured value of the encoder system is corrected based on the above-mentioned correction information, but the present invention is not limited to this. For example, while driving the wafer stage WST based on the measured value of the encoder system, the wafer is based on the above-mentioned correction information. The target position for positioning the stage WST may be corrected. Alternatively, especially in the exposure operation, the position of the reticle stage RST may be corrected based on the above-mentioned correction information while driving the wafer stage WST based on the measured value of the encoder system, for example.
0201Further, in the above embodiment, for example, only the wafer stage WST is driven based on the measured value of the encoder system at the time of exposure, but for example, an encoder system for measuring the position of the reticle stage RST is added. The reticle stage RST may be driven based on the measured value of the encoder system and the correction information corresponding to the position information of the reticle stage in the non-measurement direction measured by the reticle interferometer 116.
0202Further, in the above embodiment, one fixed primary alignment system and four movable secondary alignment systems are provided, and alignments provided to 16 alignment shot regions on the wafer in a sequence corresponding to these five alignment systems. The case of detecting the mark has been described. However, the secondary alignment system does not have to be movable, and the number of secondary alignment systems does not matter. In short, it suffices if there is at least one alignment system capable of detecting the alignment mark on the wafer.
0203In the above embodiment, an exposure apparatus having a measurement stage MST in addition to the wafer stage WST has been described as in the exposure apparatus disclosed in, for example, WO 2005/074014, but the present invention is not limited to this. Two wafers, for example, as disclosed in JP-A-10-214783 and the corresponding US Pat. No. 6,341,007, and WO 98/40791 and the corresponding US Pat. No. 6,262,796. Even in a twin-wafer stage type exposure device that can perform exposure operation and measurement operation (for example, mark detection by an alignment system) using a stage in almost parallel manner, each wafer uses the above-mentioned encoder system (Fig. 3). It is possible to control the position of the stage. Here, by appropriately setting the arrangement, length, etc. of each head unit not only during the exposure operation but also during the measurement operation, it is possible to control the position of each wafer stage using the above-mentioned encoder system as it is. However, in addition to the above-mentioned head units (62A to 62D), a head unit that can be used during the measurement operation may be provided. For example, four head units arranged in a cross shape around one or two alignment systems are provided, and the position of each wafer stage WST is determined by these head units and the corresponding moving scales (62A to 62D) during the above measurement operation. Information may be measured. In the twin wafer stage type exposure apparatus, at least two moving scales are provided for each of the two wafer stages, and when the exposure operation of the wafer mounted on one wafer stage is completed, the exposure operation with the other wafer stage is completed. By replacement, the other wafer stage on which the next wafer whose mark has been detected at the measurement position is placed is placed at the exposure position. Further, the measurement operation performed in parallel with the exposure operation is not limited to the detection of marks on the wafer or the like by the alignment system, and instead or in combination with the detection, the surface information (step information, etc.) of the wafer is detected. You may go.
0204In the above embodiment, the case where Sec-BCHK (interval) is performed using the CD bar 46 on the measurement stage MST side while each wafer is exchanged on the wafer stage WST side has been described. At least one of illuminance unevenness measurement (and illuminance measurement), spatial image measurement, wave surface aberration measurement, etc. is performed using the measuring instrument (measurement member) of the measurement stage MST, and the measurement result is performed after that. It may be reflected in the exposure of the wafer. Specifically, for example, the projection optical system PL can be adjusted by the adjusting device 68 based on the measurement result.
0205Further, in the above embodiment, a scale may be arranged on the measurement stage MST, and the position of the measurement stage may be controlled by using the above-mentioned encoder system (head unit). That is, the moving body that measures the position information by the encoder system is not limited to the wafer stage.
0206Considering the miniaturization and weight reduction of the wafer stage WST, it is preferable to arrange the scale on the wafer stage WST as close as possible to the wafer W, but when it is permissible to enlarge the wafer stage, the wafer By enlarging the stage and widening the space between the pair of scales arranged facing each other, it is possible to measure a total of four position information, two each in the X-axis and Y-axis directions, at least during the wafer exposure operation. good. Further, instead of enlarging the wafer stage, for example, the scale is provided so that a part of the scale protrudes from the wafer stage, or the scale is arranged outside the wafer stage main body by using an auxiliary plate provided with at least one scale. In the same way, the distance between the pair of scales arranged so as to face each other may be widened.
0207Further, in the above embodiment, Y scale 39Y<sub>1</sub>, 39Y<sub>2</sub>, X scale 39X<sub>1</sub>, 39X<sub>2</sub>In order to prevent deterioration of measurement accuracy due to foreign matter adhering to the surface or dirt, for example, the surface may be coated or provided with a cover glass so as to cover at least the diffraction grating. In this case, particularly in an immersion type exposure apparatus, a liquid-repellent protective film may be coated on the scale (lattice surface), or a liquid-repellent film may be formed on the surface (upper surface) of the cover glass. Further, although the diffraction grating is continuously formed over almost the entire longitudinal direction of each scale, for example, the diffraction grating may be divided into a plurality of regions and formed intermittently, or each of them may be formed intermittently. The moving scale may be composed of a plurality of scales. Further, in the above embodiment, the case where a diffraction interference type encoder is used as the encoder has been illustrated, but the present invention is not limited to this, and a so-called pickup method, a magnetic method, or the like can also be used. A so-called scan encoder or the like disclosed in a document or the like can also be used.
0208Further, in the above embodiment, as the Z sensor, instead of the above-mentioned optical pickup type sensor, for example, a probe beam is projected onto the measurement target surface and the reflected light is received to displace the measurement target surface in the Z axis direction. A first sensor (which may be an optical pickup type sensation or another optical displacement sensor) that optically reads the first sensor, a drive unit that drives the first sensor in the Z-axis direction, and a first sensor. A sensor having a configuration including a second sensor (for example, an encoder) for measuring the displacement of the sensor in the Z-axis direction may be used. In the Z sensor having such a configuration, the drive unit Z the first sensor based on the output of the first sensor so that the distance between the measurement target surface, for example, the scale surface and the first sensor in the Z axis direction is always constant. A mode that drives in the axial direction (first servo control mode) and a target value of the second sensor are given from the outside (control device), and the drive unit sets the target value so that the measured value of the second sensor matches this target value. , The position of the first sensor in the Z-axis direction can be maintained (first servo control mode). In the case of the first servo control mode, the output of the measuring unit (second sensor) can be used as the output of the Z sensor, and in the case of the second servo control mode, the output of the second sensor can be used. .. Further, when such a Z sensor is used and an encoder is used as the second sensor, as a result, the position information in the 6 degrees of freedom direction of the wafer stage WST (wafer table WTB) is measured by using the encoder. be able to. Further, in the above embodiment, a sensor of another detection method can be adopted as the Z sensor.
0209Further, in the above embodiment, the configurations and combinations of the plurality of interferometers for measuring the position information of the wafer stage WST are not limited to the configurations and combinations described above. In short, the configuration and combination of the interferometers are not particularly limited as long as the position information of the wafer stage WST in the direction other than the measurement direction of the encoder system can be measured. In short, in addition to the encoder system described above, a measuring device (whether or not it is an interferometer) capable of measuring the position information of the wafer stage WST in a direction other than the measuring direction of the encoder system may be provided. For example, the above-mentioned Z sensor may be used as a measuring device.
0210Further, in the above embodiment, the Z sensor is provided in addition to the multi-point AF system. For example, since the multi-point AF system can detect the surface position information in the exposure target shot region of the wafer W during exposure. If so, the Z sensor does not necessarily have to be provided.
0211In the above embodiment, pure water (water) is used as the liquid, but it goes without saying that the present invention is not limited to this. As the liquid, a chemically stable liquid having a high transmittance of illumination light IL and a safe liquid, for example, a fluorine-based inert liquid may be used. As the fluorine-based inert liquid, for example, Fluorinert (trade name of 3M, Inc., USA) can be used. This fluorine-based inert liquid is also excellent in terms of cooling effect. Further, as the liquid, a liquid having a refractive index with respect to the illumination light IL higher than that of pure water (refractive index of about 1.44), for example, 1.5 or more may be used. Examples of this liquid include isopropanol having a refractive index of about 1.50, a predetermined liquid having a CH bond or an OH bond such as glycerol (glycerin) having a refractive index of about 1.61, and a predetermined liquid (organic solvent) such as hexane, heptane, and decan. Alternatively, decalin (Decalin: Decahydronaphthalene) having a refractive index of about 1.60 can be mentioned. Alternatively, any two or more kinds of liquids among these predetermined liquids may be mixed, or the predetermined liquid may be added (mixed) to pure water. Alternatively, as a liquid, pure water, H<sup>+</sup>, Cs<sup>+</sup>, K<sup>+</sup>, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, PO<sub>4</sub><sup>2-</sup>Such bases or acids may be added (mixed). Further, fine particles such as Al oxide may be added (mixed) to pure water. These liquids are capable of transmitting ArF excimer laser light. Further, as a liquid, the light absorption coefficient is small, the temperature dependence is small, and the photosensitive material (or protective film (top coat film)) coated on the surface of the projection optical system (optical member at the tip) and / or the wafer is applied. ) Or antireflection film, etc.). Also, F<sub>2</sub>When using a laser as a light source, von Bryn oil may be selected.
0212Further, in the above embodiment, the recovered liquid may be reused. In this case, it is desirable to provide a filter for removing impurities from the recovered liquid in the liquid recovery device, the recovery pipe, or the like. ..
0213In the above embodiment, the case where the exposure apparatus is an immersion type exposure apparatus has been described, but the present invention is not limited to this, and a dry type exposure in which the wafer W is exposed without using a liquid (water). The present invention can also be suitably applied to an apparatus.
0214Further, in the above embodiment, the case where the present invention is applied to a scanning exposure apparatus such as a step-and-scan method has been described, but the present invention is not limited to this, and the present invention is applied to a static exposure apparatus such as a stepper. You may. Even with a stepper or the like, by measuring the position of the stage on which the object to be exposed is mounted with an encoder, it is possible to similarly eliminate the occurrence of position measurement error due to air fluctuations. In this case, the stage can be positioned with high accuracy based on the measured value of the encoder and the above-mentioned correction information, and as a result, the reticle pattern can be transferred onto the object with high accuracy. The present invention can also be applied to a step-and-stitch type reduction projection exposure apparatus for synthesizing a shot region and a shot region, a proximity type exposure apparatus, a mirror projection aligner, and the like.
0215Further, the magnification of the projection optical system in the exposure apparatus of the above embodiment may be not only a reduction system but also an equal magnification system and an enlargement system, and the projection optical system PL is not only a refraction system but also a reflection system or a reflection refraction system. However, the projected image may be either an inverted image or an upright image. Further, the exposure region in which the illumination light IL is irradiated through the projection optical system PL is an on-axis region including the optical axis AX in the field of view of the projection optical system PL, which is disclosed in, for example, International Publication No. 2004/107011. An optical system (catadioptric system or catadioptric system) having a plurality of reflecting surfaces and forming an intermediate image at least once is provided in a part thereof, and has a single optical axis, so-called in-line. Similar to the catadioptric system of the type, the exposure region may be an off-axis region that does not include the optical axis AX. Further, the above-mentioned illumination area and exposure area are assumed to have a rectangular shape, but the shape is not limited to this, and may be, for example, an arc, a trapezium, or a parallelogram.
0216The light source of the exposure apparatus of the above embodiment is not limited to the ArF excimer laser, but is a KrF excimer laser (output wavelength 248 nm), F.<sub>2</sub>Laser (output wavelength 157 nm), Ar<sub>2</sub>Laser (output wavelength 126 nm), Kr<sub>2</sub>It is also possible to use a pulsed laser light source such as a laser (output wavelength 146 nm), or an ultrahigh pressure mercury lamp that emits bright lines such as g-line (wavelength 436 nm) and i-line (wavelength 365 nm). Further, a harmonic generator of a YAG laser or the like can also be used. In addition, for example, as disclosed in International Publication No. 1999/46835 (corresponding US Patent No. 7,023,610), the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser as vacuum ultraviolet light. Single-wavelength laser light may be amplified by, for example, a fiber amplifier doped with erbium (or both erbium and itterbium), and a harmonic whose wavelength is converted to ultraviolet light using a nonlinear optical crystal may be used.
0217Further, in the above embodiment, it goes without saying that the illumination light IL of the exposure apparatus is not limited to light having a wavelength of 100 nm or more, and light having a wavelength of less than 100 nm may be used. For example, in recent years, in order to expose a pattern of 70 nm or less, EUV (Extreme Ultraviolet) light in the soft X-ray region (for example, a wavelength range of 5 to 15 nm) is generated using a SOR or a plasma laser as a light source, and the exposure wavelength thereof is generated. An all-reflection reduction optical system designed under (for example, 13.5 nm) and an EUV exposure device using a reflective mask are being developed. In this apparatus, since it is conceivable that the mask and the wafer are synchronously scanned and scanned and exposed using arc illumination, the present invention can be suitably applied to such an apparatus. In addition, the present invention can be applied to an exposure apparatus using a charged particle beam such as an electron beam or an ion beam.
0218Further, in the above-described embodiment, a light-transmitting mask (reticle) in which a predetermined light-shielding pattern (or phase pattern / dimming pattern) is formed on a light-transmitting substrate is used, but instead of this reticle, For example, as disclosed in US Pat. No. 6,778,257, an electronic mask (variable molding mask, active mask, or electronic mask) that forms a transmission pattern, a reflection pattern, or a light emission pattern based on the electronic data of the pattern to be exposed. It is also called an image generator, and for example, a DMD (Digital Micro-mirror Device), which is a kind of non-emission type image display element (spatial light modulator), may be used. When such a variable molding mask is used, a stage on which a wafer, a glass plate, or the like is mounted is scanned with respect to the variable molding mask. Therefore, the position of the stage is measured using an encoder, and the measured value of the encoder is measured. By driving the stage based on the correction information according to the position information in the non-measurement direction of the stage measured by the interferometer, the same effect as that of the above embodiment can be obtained.
0219In addition, as disclosed in, for example, International Publication No. 2001/035168, this is also applied to an exposure apparatus (lithography system) that forms a line-and-space pattern on a wafer by forming interference fringes on the wafer. The invention can be applied.
0220Further, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-519850 (corresponding US Pat. No. 6,611,316), two reticle patterns are synthesized on a wafer via a projection optical system, and one scan exposure is performed. The present invention can also be applied to an exposure apparatus that double-exposes one shot region on a wafer at almost the same time.
0221Further, the apparatus for forming a pattern on an object is not limited to the above-mentioned exposure apparatus (lithography system), and the present invention can be applied to, for example, an apparatus for forming a pattern on an object by an inkjet method.
0222The object (the object to be exposed to which the energy beam is irradiated) to which the pattern should be formed in the above embodiment and the modified example is not limited to the wafer, but is not limited to the wafer, but may be a glass plate, a ceramic substrate, a film member, a mask blank, or the like. It may be an object of.
0223The application of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern onto a square glass plate, an organic EL, a thin film magnetic head, and an image pickup device. It can be widely applied to exposure equipment for manufacturing (CCD, etc.), micromachines, DNA chips, and the like. Further, in order to manufacture reticle or mask used not only in microdevices such as semiconductor elements but also in optical exposure equipment, EUV exposure equipment, X-ray exposure equipment, electron beam exposure equipment, etc., glass substrates, silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a wafer.
0224The moving body driving system, moving body driving method, or determining method of the present invention is not limited to the exposure apparatus, but is not limited to the exposure apparatus, but is another substrate processing apparatus (for example, a laser repair apparatus, a substrate inspection apparatus, etc.), or another precision machine. It can be widely applied to a device having a moving body such as a stage that moves in a two-dimensional plane such as a sample positioning device and a wire bonding device in the above.
0225Further, the exposure apparatus (pattern forming apparatus) of the above-described embodiment is such that various subsystems including each component listed in the claims of the present application maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. , Manufactured by assembling. In order to ensure these various accuracy, before and after this assembly, adjustments for achieving optical accuracy for various optical systems, adjustments for achieving mechanical accuracy for various mechanical systems, and various electrical systems Is adjusted to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connections between the various subsystems, wiring connections of electric circuits, piping connections of atmospheric pressure circuits, and the like. It goes without saying that there is an individual assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. After the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracy of the exposure apparatus as a whole. It is desirable that the exposure apparatus is manufactured in a clean room where the temperature, cleanliness, etc. are controlled.
0226In addition, all the publications, international publications, US patent application publication specifications, and disclosures of US patent specifications relating to the exposure apparatus and the like cited in the above-described embodiment are incorporated as a part of the description of this specification.
0227Next, an embodiment of a method for manufacturing a device using the above-mentioned exposure apparatus (pattern forming apparatus) in the lithography process will be described.
0228FIG. 28 shows a flowchart of a manufacturing example of a device (semiconductor chip such as IC or LSI, liquid crystal panel, CCD, thin film magnetic head, micromachine, etc.). As shown in FIG. 28, first, in step 201 (design step), the function / performance design of the device (for example, the circuit design of the semiconductor device, etc.) is performed, and the pattern design for realizing the function is performed. Subsequently, in step 202 (mask manufacturing step), a mask forming the designed circuit pattern is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.
0229Next, in step 204 (wafer processing step), an actual circuit or the like is formed on the wafer by a lithography technique or the like, as described later, using the mask and the wafer prepared in steps 201 to 203. Next, in step 205 (device assembly step), device assembly is performed using the wafer processed in step 204. This step 205 includes steps such as a dicing step, a bonding step, and a packaging step (chip encapsulation), if necessary.
0230Finally, in step 206 (inspection step), an inspection such as an operation confirmation test and an endurance test of the device created in step 205 is performed. After going through these steps, the device is completed and shipped.
0231FIG. 29 shows a detailed flow example of step 204 in the semiconductor device. In FIG. 29, in step 211 (oxidation step), the surface of the wafer is oxidized. In step 212 (CVD step), an insulating film is formed on the wafer surface. In step 213 (electrode forming step), electrodes are formed on the wafer by thin film deposition. In step 214 (ion driving step), ions are driven into the wafer. Each of the above steps 211 to 214 constitutes a pretreatment step of each stage of wafer processing, and is selected and executed according to the processing required in each stage.
0232When the above-mentioned pretreatment step is completed at each stage of the wafer process, the post-treatment step is executed as follows. In this post-treatment step, first, in step 215 (resist forming step), a photosensitizer is applied to the wafer. Subsequently, in step 216 (exposure step), the circuit pattern of the mask is transferred to the wafer by the exposure apparatus (pattern forming apparatus) described above and the exposure method (pattern forming method) thereof. Next, in step 217 (development step), the exposed wafer is developed, and in step 218 (etching step), the exposed member of the portion other than the portion where the resist remains is removed by etching. Then, in step 219 (resist removal step), the resist that has been etched and is no longer needed is removed.
0233By repeating these pretreatment steps and posttreatment steps, multiple circuit patterns are formed on the wafer.
0234If the device manufacturing method of the present embodiment described above is used, the exposure apparatus (pattern forming apparatus) of the above embodiment and the exposure method (pattern forming method) of the above embodiment are used in the exposure step (step 216), so that the overlay accuracy can be improved. It is possible to perform high-throughput exposure while maintaining a high level. Therefore, it is possible to improve the productivity of the highly integrated microdevice in which the fine pattern is formed.
0235As described above, the exposure apparatus and exposure method of the present invention and the device manufacturing method are suitable for manufacturing microdevices.
023610 ... lighting system, 11 ... reticle stage drive system, 16 ... Y interferometer, 20 ... main controller, 34 ... memory, 37 ... grid line, 38 ... grid Line, 39Y<sub>1</sub>, 39Y<sub>2</sub>... Y scale, 39X<sub>1</sub>, 39X<sub>2</sub>... X scale, 43A, 43B ... Z interferometer, 64 ... Y head, 66 ... X head, 70A ~ 70F ... encoder, 100 ... exposure device, 124 ... stage Drive system, 126 ... X interferometer, WST ... wafer stage, R ... reticle, W ... wafer, PL ... projection optical system, Lq ... water, RST ... reticle stage ..
29 sheets
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Priority claims2
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Numbers
- Publication
- 5907397
- Application
- 2357
Titles2
- Japanese
- 露光方法及び露光装置、並びにデバイス製造方法
- English
- Exposure method, exposure equipment, and device manufacturing method
Classification
- CPC, 6
- G03F7/70775
- G03F7/70341
- G03F7/70716
- G03F7/2041
- G03F7/7085
- G03F7/70725
- IPC, 4
- G03F7 20
- H01L21 68
- H10P72 30
- H10P72 50
