Exposure apparatus and exposure method
20 claims: 14 independent, 6 dependent
- 1照明光でマスクを照明する照明光学系と、前記照明されたマスクのパターン像を基板上に投影する投影光学系と、を有し、前記投影光学系と液体とを介して前記照明光で前記基板を露光する液浸露光装置であって、 前記投影光学系を囲んで設けられ、前記液体を供給するノズル部材と、 前記投影光学系の上方に配置され、前記マスクを保持する第1移動体と、前記第1移動体を駆動する第1電磁モータと、を有する第1ステージシステムと、 前記マスクのマーク又は前記第1移動体のマークを検出する第1検出系と、 前記投影光学系の光軸と直交する所定面と実質的に平行に配置され、反射型格子を有する第1格子部に対して、それぞれ第1計測ビームを照射する複数の第1ヘッドを有し、前記第1電磁モータによって移動される前記第1移動体の位置情報を計測する第1エンコーダシステムと、 前記投影光学系の下方に配置され、前記基板を保持する第2移動体と、前記第2移動体を駆動する第2電磁モータとを有する第2ステージシステムと、 前記基板のマーク又は前記第2移動体のマークを検出する第2検出系と、 前記所定面と実質的に平行に配置され、反射型格子を有する第2格子部に対して、それぞれ第2計測ビームを照射する複数の第2ヘッドを有し、前記第2電磁モータによって移動される前記第2移動体の位置情報を計測する第2エンコーダシステムと、 前記基板の露光動作において、前記照明光に対して前記マスクと前記基板とをそれぞれ相対移動するために、前記第1エンコーダシステムの計測情報に基づいて前記第1電磁モータによる前記第1移動体の駆動を制御するとともに、前記第2エンコーダシステムの計測情報に基づいて前記第2電磁モータによる前記第2移動体の駆動を制御する制御システムと、を備え、 前記露光動作と、前記第1検出系による前記マークの検出動作とでそれぞれ、前記第1エンコーダシステムによって前記第1移動体の位置情報が計測され、 前記露光動作と、前記第2検出系による前記マークの検出動作とでそれぞれ、前記第2エンコーダシステムによって前記第2移動体の位置情報が計測され、 前記複数の第2ヘッドのうち前記第2格子部と対向する3つ又は4つの第2ヘッドによって前記第2移動体の位置情報が計測されるとともに、前記第2移動体の移動によって、前記第2格子部と対向する第2ヘッドが、前記3つの第2ヘッドと前記4つの第2ヘッドとの一方から他方に変化す る液浸露光装置。
- 2請求項1に記載の液浸露光装置において、 前記第1移動体に保持されるマスクの交換動作において、前記第1エンコーダシステムによって前記第1移動体の位置情報が計測される液浸露光装置。
- 3請求項1又は2に記載の液浸露光装置において、 前記第2移動体に保持される基板の交換動作において、前記第2エンコーダシステムによって前記第2移動体の位置情報が計測される液浸露光装置。
- 4請求項1~3のいずれか一項に記載の液浸露光装置において、 前記制御システムは、前記第2格子部と前記第2ヘッドとの少なくとも一方に起因して生じる前記第2エンコーダシステムの計測誤差を補償しつつ前記第2移動体の駆動を制御する液浸露光装置。
- 5請求項4に記載の液浸露光装置において、 前記制御システムは、前記第2格子部に形成される格子のピッチと変形との少なくとも一方に関する補正情報を用いて前記第2移動体の駆動を制御する液浸露光装置。
- 6請求項4又は5に記載の液浸露光装置において、 前記制御システムは、前記第2ヘッドの倒れと光学特性との少なくとも一方に関する補正情報を用いて前記第2移動体の駆動を制御する液浸露光装置。
- 7請求項1~6のいずれか一項に記載の液浸露光装置において、 前記第2ステージシステムは、それぞれ基板を保持する、前記第2移動体を含む複数の第2移動体を有し、 前記第2エンコーダシステムはその一部が前記第2検出系の周囲に配置されるとともに、前記複数の第2移動体の位置情報を計測する液浸露光装置。
- 8請求項1~ 7 のいずれか一項に記載の液浸露光装置において、 前記第2格子部は、それぞれ格子が形成される複数のスケールを含み、 前記複数の第2ヘッドのうち前記複数のスケールにそれぞれ対向する第2ヘッドによって前記第2移動体の位置情報が計測される液浸露光装置。
- 9請求項 8 に記載の液浸露光装置において、 前記第2格子部は、前記スケールを4つ含み、 前記4つのスケールの少なくとも3つとそれぞれ対向する第2ヘッドによって前記第2移動体の位置情報が計測される液浸露光装置。
- 10照明光でマスクを照明するとともに、投影光学系と液体とを介して前記照明光で基板を露光する液浸露光方法であって、 前記投影光学系を囲んで設けられるノズル部材によって、前記投影光学系と前記基板との間に前記液体を供給することと、 前記投影光学系の上方に配置され、前記マスクを保持する第1移動体と、前記第1移動体を駆動する第1電磁モータと、を有する第1ステージシステムによって、前記マスクのマーク又は前記第1移動体のマークが第1検出系で検出されるように前記第1移動体を移動することと、 前記投影光学系の光軸と直交する所定面と実質的に平行に配置され、反射型格子を有する第1格子部に対して、それぞれ第1計測ビームを照射する複数の第1ヘッドを有する第1エンコーダシステムによって、前記第1電磁モータで駆動される前記第1移動体の位置情報を計測することと、 前記投影光学系の下方に配置され、前記基板を保持する第2移動体と、前記第2移動体を駆動する第2電磁モータとを有する第2ステージシステムによって、前記基板のマーク又は前記第2移動体のマークが第2検出系で検出されるように前記第2移動体を移動することと、 前記所定面と実質的に平行に配置され、反射型格子を有する第2格子部に対して、それぞれ第2計測ビームを照射する複数の第2ヘッドを有する第2エンコーダシステムによって、前記第2電磁モータで駆動される前記第2移動体の位置情報を計測することと、 前記基板の露光動作において、前記照明光に対して前記マスクと前記基板とをそれぞれ相対移動するために、前記第1エンコーダシステムの計測情報に基づいて前記第1電磁モータによる前記第1移動体の駆動を制御するとともに、前記第2エンコーダシステムの計測情報に基づいて前記第2電磁モータによる前記第2移動体の駆動を制御することと、を含み、 前記露光動作と、前記第1検出系による前記マークの検出動作とでそれぞれ、前記第1エンコーダシステムによって前記第1移動体の位置情報が計測され、 前記露光動作と、前記第2検出系による前記マークの検出動作とでそれぞれ、前記第2エンコーダシステムによって前記第2移動体の位置情報が計測され、 前記複数の第2ヘッドのうち前記第2格子部と対向する3つ又は4つの第2ヘッドによって前記第2移動体の位置情報が計測されるとともに、前記第2移動体の移動によって、前記第2格子部と対向する第2ヘッドが、前記3つの第2ヘッドと前記4つの第2ヘッドとの一方から他方に変化す る液浸露光方法。
- 11請求項 10 に記載の液浸露光方法において、 前記第1移動体に保持されるマスクの交換動作において、前記第1エンコーダシステムによって前記第1移動体の位置情報が計測される液浸露光方法。
- 12請求項 10 又は 11 に記載の液浸露光方法において、 前記第2移動体に保持される基板の交換動作において、前記第2エンコーダシステムによって前記第2移動体の位置情報が計測される液浸露光方法。
- 13請求項 10 ~ 12 のいずれか一項に記載の液浸露光方法において、 前記第2格子部と前記第2ヘッドとの少なくとも一方に起因して生じる前記第2エンコーダシステムの計測誤差が補償されつつ前記第2移動体の駆動が制御される液浸露光方法。
- 14請求項 13 に記載の液浸露光方法において、 前記第2格子部に形成される格子のピッチと変形との少なくとも一方に関する補正情報を用いて前記第2移動体の駆動が制御される液浸露光方法。
- 15請求項 13 又は 14 に記載の液浸露光方法において、 前記第2ヘッドの倒れと光学特性との少なくとも一方に関する補正情報を用いて前記第2移動体の駆動が制御される液浸露光方法。
- 16請求項 10 ~ 15 のいずれか一項に記載の液浸露光方法において、 前記第2移動体を含む複数の第2移動体によってそれぞれ基板が保持されるとともに、前記第2検出系の周囲に一部が配置される前記第2エンコーダシステムによって、前記複数の第2移動体の位置情報が計測される液浸露光方法。
- 17請求項 10 ~ 16 のいずれか一項に記載の液浸露光方法において、 前記第2格子部は、それぞれ格子が形成される複数のスケールを含み、 前記複数の第2ヘッドのうち前記複数のスケールにそれぞれ対向する第2ヘッドによって前記第2移動体の位置情報が計測される液浸露光方法。
- 18請求項 17 に記載の液浸露光方法において、 前記第2格子部は、前記スケールを4つ含み、 前記4つのスケールの少なくとも3つとそれぞれ対向する第2ヘッドによって前記第2移動体の位置情報が計測される液浸露光方法。
- 19デバイス製造方法であって、 請求項1~ 9 のいずれか一項に記載の液浸露光装置を用いて基板にパターンを転写するリソグラフィ工程を含むデバイス製造方法。
- 20デバイス製造方法であって、 請求項 10 ~ 18 のいずれか一項に記載の液浸露光方法を用いて基板にパターンを転写するリソグラフィ工程を含むデバイス製造方法。
Independent claims20
222 paragraphs, as filed
0001The present invention relates to an immersion exposure apparatus and an immersion exposure method, and a device manufacturing method, and in particular, an immersion exposure apparatus and an immersion exposure method used in a lithography process in the manufacture of a microdevice (electronic device, etc.), and a liquid. The present invention relates to a device manufacturing method using an immersion exposure apparatus or an immersion exposure method.
0002Conventionally, in the lithography process in the manufacture of microdevices (electronic devices, etc.) such as semiconductor elements and liquid crystal display elements, a step-and-repeat reduction projection exposure apparatus (so-called stepper) or a step-and-scan scanning type is used. Projection exposure devices (so-called scanning steppers (also called scanners)) are relatively often used.
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 and the wafer stage is generally performed by using a laser interferometer having good stability of measured values 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 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 are becoming non-negligible.
0005On the other hand, recently, as an encoder which is a kind of position measuring device, one having a measuring resolution equal to or higher than that of a laser interferometer has appeared (see, for example, Patent Document 1). However, since the encoder uses a scale (grating), there are various error factors (grid pitch drift, fixed position drift, thermal expansion, etc.) that occur in the scale over time, and mechanical long-term stability. Lacking. Therefore, the encoder has a drawback that it lacks the linearity of the measured value and is inferior in long-term stability as compared with the laser interferometer.
<p num="0006"><patcit num="1"><text>U.S. Pat. No. 6,639,686</text></patcit></p>
<p num="0007"> According to the first aspect of the present invention, it has an illumination optical system that illuminates a mask with illumination light and a projection optical system that projects a pattern image of the illuminated mask onto a substrate, and includes a projection optical system and a liquid. A immersion exposure device that exposes a substrate with illumination light via the above, a nozzle member that surrounds a projection optical system and supplies liquid, and a third that is arranged above the projection optical system and holds a mask. Light from a first stage system having one moving body and a first electromagnetic motor to drive the first moving body, a first detection system that detects a mask mark or a first moving body mark, and a projection optical system. A first electromagnetic motor has a plurality of first heads that irradiate a first measurement beam to a first grid portion that is arranged substantially parallel to a predetermined surface orthogonal to the axis and has a reflective grid. A first encoder system that measures the position information of the first moving body to be moved, a second moving body that is placed below the projection optical system and holds the substrate, and a second electromagnetic motor that drives the second moving body. With respect to the second stage system having the above, the second detection system for detecting the mark of the substrate or the mark of the second moving body, and the second lattice portion having the reflection type lattice, which is arranged substantially parallel to the predetermined surface. The second encoder system, which has a plurality of second heads for irradiating the second measurement beam and measures the position information of the second moving body moved by the second electromagnetic motor, and the illumination light in the exposure operation of the substrate. In order to move the mask and the substrate relative to each other, the drive of the first moving body by the first electromagnetic motor is controlled based on the measurement information of the first encoder system, and based on the measurement information of the second encoder system. It is equipped with a control system that controls the drive of the second moving body by the second electromagnetic motor, and the position of the first moving body by the first encoder system in the exposure operation and the mark detection operation by the first detection system, respectively. Information is measured, and the position information of the second moving object is measured by the second encoder system in the exposure operation and the mark detection operation by the second detection system, respectively.<u style="single">, The position information of the second moving body is measured by three or four second heads facing the second lattice portion among the plurality of second heads, and the movement of the second moving body causes the movement of the second moving body. The second head facing the second lattice portion changes from one of the three second heads and the four second heads to the other.</u>An immersion exposure apparatus is provided.</p><p num="0008"> According to this, the position information of the first moving body is measured by the first encoder system in the exposure operation of the substrate and the mark detection operation by the first detection system, respectively, and the exposure operation of the substrate and the second detection system are performed. The position information of the second moving body is measured by the second encoder system in each of the mark detection operations by.</p><p num="0009"> According to the second aspect of the present invention, it is a immersion exposure method in which a mask is illuminated with illumination light and a substrate is exposed with illumination light via a projection optical system and a liquid, and surrounds the projection optical system. A nozzle member provided supplies liquid between the projection optical system and the substrate, and a first moving body that is arranged above the projection optical system and holds a mask, and a first moving body that drives the first moving body. The first stage system with an electromagnetic motor moves the first moving body so that the mask mark or the first moving body mark is detected by the first detection system, and the optical axis of the projection optical system. The first electromagnetic wave is provided by a first encoder system having a plurality of first heads, each of which irradiates a first measurement beam to a first lattice portion having a reflective lattice, which is arranged substantially parallel to predetermined planes orthogonal to each other. The position information of the first moving body driven by the motor is measured, and the second moving body, which is arranged below the projection optical system and holds the substrate, and the second electromagnetic motor that drives the second moving body The second stage system has the movement of the second moving body so that the mark on the substrate or the mark of the second moving body is detected by the second detection system, and is arranged substantially parallel to the predetermined surface and reflected. The position information of the second moving body driven by the second electromagnetic motor is measured by the second encoder system having a plurality of second heads that irradiate the second measurement beam to the second lattice portion having the mold lattice. In order to move the mask and the substrate relative to the illumination light in the exposure operation of the substrate, the drive of the first moving body by the first electromagnetic motor is controlled based on the measurement information of the first encoder system. In addition, the exposure operation and the mark detection operation by the first detection system include controlling the drive of the second moving object by the second electromagnetic motor based on the measurement information of the second encoder system, respectively. The position information of the first moving body is measured by the first encoder system, and the position information of the second moving body is measured by the second encoder system in the exposure operation and the mark detection operation by the second detection system, respectively.<u style="single">, The position information of the second moving body is measured by three or four second heads facing the second lattice portion among the plurality of second heads, and the movement of the second moving body causes the movement of the second moving body. The second head facing the second lattice portion changes from one of the three second heads and the four second heads to the other.</u>An immersion exposure method is provided.</p><p num="0010"> According to this, the position information of the first moving body is measured by the first encoder system in the exposure operation of the substrate and the mark detection operation by the first detection system, respectively, and the exposure operation of the substrate and the second detection system are performed. The position information of the second moving body is measured by the second encoder system in each of the mark detection operations by.</p><p num="0011"> According to a third aspect of the present invention, there is provided a device manufacturing method including a lithography step of transferring a pattern to a substrate using the immersion exposure apparatus according to the first aspect.</p><p num="0012"> According to a fourth aspect of the present invention, there is provided a device manufacturing method including a lithography step of transferring a pattern to a substrate by using the immersion exposure method according to the second aspect.</p>
0013<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 reticle stage together with the encoder system and the interferometer system which measure the position information of the reticle stage.</figref><figref num="3">It is a top view which shows the wafer stage together with the encoder and the interferometer which measure the position information of the wafer stage.</figref><figref num="4">It is a figure which takes out and shows the Y interferometer for measuring the position of the wafer stage WST of FIG. 1, the Z interferometer and the component part in the vicinity thereof.</figref><figref num="5">It is a figure which shows an example of the structure of an encoder.</figref><figref num="6">It is a block diagram which shows partially omitting the control system which concerns on the stage control of the exposure apparatus which concerns on one Embodiment.</figref><figref num="7">It is a figure (part 1) for demonstrating the switching operation of a position measurement system.</figref><figref num="8">It is a figure (2) for demonstrating the switching operation of a position measurement system.</figref><figref num="9">It is a figure (part 1) for demonstrating the scanning operation of the reticle stage for exposure including the operation of switching (connecting the measured values) of the encoder on the reticle side.</figref><figref num="10">It is a figure (2) for demonstrating the scanning operation of the reticle stage for exposure including the operation of switching (connecting measured values) of the encoder on the reticle side.</figref><figref num="11">It is a figure (3) for demonstrating the scanning operation of the reticle stage for exposure including the operation of switching (connecting measured values) of the encoder on the reticle side.</figref><figref num="12">FIG. 12 (A) shows a state in which the wafer stage is located at a position where the vicinity of the center of the wafer is directly below the projection unit, and FIG. 12 (B) shows a state in which the vicinity between the center and the outer periphery of the wafer is directly below the projection unit. It is a figure which shows the state which the wafer stage is in the position | position.</figref><figref num="13">FIG. 13 (A) shows a state in which the wafer stage is located at a position where the vicinity of the edge on the + Y side of the wafer is directly below the projection unit PU, and FIG. 13 (B) shows the X-axis and the X-axis when viewed from the center of the wafer. It is a figure which shows the state which the wafer stage is in the position where the vicinity of the edge in the direction which forms 45 ° with respect to the Y axis is directly under the projection unit PU.</figref><figref num="14">It is a figure which shows the state which the wafer stage is in the position where the vicinity of the edge on the + X side of a wafer is directly under the projection unit PU.</figref><figref num="15">Encoder 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>It is a diagram which shows an example of the map obtained by the 1st calibration operation of.</figref><figref num="16">Encoder 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>It is a figure (the 1) for explaining the 2nd calibration operation which calibrates the measurement error of.</figref><figref num="17">Encoder 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>It is a figure (2) for explaining the 2nd calibration operation which calibrates the measurement error of.</figref><figref num="18">It is a figure which shows an example of the map obtained by the 2nd calibration operation.</figref><figref num="19">Encoder 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>It is a figure which shows an example of the map obtained by the 2nd calibration operation which calibrates the measurement error of.</figref><figref num="20">It is a figure for demonstrating the long-term calibration operation (the first calibration operation) of the measured value of encoders 50A to 50D, that is, the acquisition operation of the correction information of the lattice pitch of the moving scale, and the correction information of the lattice deformation.</figref><figref num="21">It is a figure which shows the measurement value of the interferometer and the encoder obtained by the sequential calibration of the measurement error of an encoder.</figref><figref num="22">It is a figure (the 1) for demonstrating the acquisition operation of the correction information of the lattice pitch of the moving scales 44A, 44C which concerns on a modification.</figref><figref num="23">It is a figure (the 2) for demonstrating the acquisition operation of the correction information of the lattice pitch of the moving scales 44A, 44C which concerns on a modification.</figref><figref num="24">It is a figure for demonstrating the acquisition operation of the correction information of the deformation (bending of a grid line) of the grid lines of the moving scales 44B, 44D which concerns on a modification.</figref><figref num="25">It is a figure which shows the modification of the encoder system for a wafer stage.</figref><figref num="26">It is a figure which shows another modification of the encoder system for a wafer stage.</figref><figref num="27">It is a figure which shows the modification of the wafer stage used in the immersion exposure apparatus.</figref>
0014Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 21.
0015FIG. 1 shows a schematic 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 scanning stepper. 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.
0016The exposure device 100 includes a light source and an illumination optical system, and includes an illumination system 10 that illuminates the reticle R1 and R2 with an illumination light (exposure light) IL, a reticle stage RST that holds the reticle R1 and R2, a projection unit PU, and a wafer W. It is equipped with a wafer stage device 12 including a wafer stage WST to be mounted, a body BD equipped with a reticle stage RST, a projection unit PU, and the like, and a control system for these.
0017The illumination system 10 uses the illumination light IL to cover the slit-shaped illumination region IAR (see FIG. 2) extending in the X-axis direction on the reticle R1 or R2 defined by the reticle blind (masking system) (not shown) with almost uniform illuminance. Illuminate. Here, as the illumination light IL, ArF excimer laser light (wavelength 193 nm) is used as an example.
0018The reticle stage RST is supported on a reticle base 36 constituting the top plate of the second column 34, which will be described later, by an air bearing (not shown) provided on the bottom surface thereof, for example, through a clearance of about several μm. There is. As the reticle stage RST, for example, a reticle stage capable of holding one reticle, or a twin reticle stage capable of holding one reticle each and moving independently can be used, but in the present embodiment, two reticles are used. A double reticle holder type reticle stage that can be held at the same time is used.
0019Here, the reticle stage RST is two-dimensionally (X-axis direction, Y-axis direction and θz direction) in the XY plane perpendicular to the optical axis AX of the projection optical system PL by the reticle stage drive system 11 including the linear motor and the like. It can be driven slightly. Further, the reticle stage RST can be driven by the reticle stage drive system 11 at a scanning speed specified in a predetermined scanning direction (here, the Y-axis direction which is the left-right direction of the paper surface in FIG. 1) on the reticle base 36. ing. The reticle stage RST may be, for example, a coarse and fine movement structure disclosed in Japanese Patent Application Laid-Open No. 8-130179 (corresponding US Pat. No. 6,721,034), and the structure is limited to the present embodiment (Fig. 2, etc.). It's not something.
0020The position information of the reticle stage RST in the XY plane (moving surface) is the reticle interferometer system including the reticle Y laser interferometer (hereinafter referred to as "reticle Y interferometer") 16y and the like shown in FIG. 1, and the encoder head. (Hereafter, abbreviated as "head") 26A<sub>1</sub>~ 26A<sub>3</sub>, 26C<sub>1</sub>~ 26C<sub>3</sub>And it is configured to be measurable by an encoder system including a moving scale 24A and so on. Note that FIG. 1 shows a state in which the upper end surfaces of the reticle R1 and R2 are exposed above the moving scale 24A, but this is shown in this way for convenience of explanation and is different from the actual state.
0021Here, the configuration of the reticle interferometer system and the encoder system for measuring the position of the reticle stage RST and its position in the XY plane (moving plane) will be described in more detail.
0022As shown in FIG. 2, a rectangular recess 22 elongated in the Y-axis direction (scanning direction) in a plan view (viewed from above) is formed in the central portion of the reticle stage RST. Two substantially square openings (not shown) are formed side by side in the Y-axis direction on the inner bottom surface of the recess 22, and the reticle R1 and the reticle R2 are arranged side by side in the Y-axis direction while covering each of these openings. Has been done. Each of the reticle R1 and R2 is vacuum-sucked by a suction mechanism (not shown) provided on both sides of the two openings on the inner bottom surface of the recess 22 in the X-axis direction, for example, a vacuum chuck.
0023Further, at the + X side end and the -X side end of the upper surface of the reticle stage RST, the center of the illumination region IAR (in the present embodiment, the optical axis thereof is within the first surface (object surface) of the projection optical system PL). A pair of moving scales 24A and 24B are extended with the Y-axis direction as the longitudinal direction in a symmetrical arrangement with respect to the central axis parallel to the Y-axis direction (which is almost the same as AX). The moving scales 24A and 24B are made of the same material (for example, ceramics or glass with low thermal expansion), and on the surface of the moving scales 24A and 24B, a reflective diffraction grating having a periodic direction in the Y-axis direction is symmetrical with respect to the central axis. It is formed by arrangement. The moving scales 24A and 24B are fixed to the reticle stage RST by, for example, vacuum suction (or leaf spring) so as not to cause local expansion and contraction.
0024Above the moving scales 24A and 24B (+ Z side), as shown in Fig. 2, two pairs of heads 26A for measuring the position in the Y-axis direction facing the moving scales 24A and 24B.<sub>1</sub>, 26A<sub>2</sub>, 26B<sub>1</sub>, 26B<sub>2</sub>Are arranged symmetrically with respect to the above-mentioned central axis (see FIG. 1). Of these, head 26A<sub>1</sub>, 26B<sub>1</sub>Is arranged at a position where the measurement center substantially coincides with the straight line (measurement axis) in the X-axis direction passing through the center of the above-mentioned illumination area IAR. Also, head 26A<sub>2</sub>, 26B<sub>2</sub>Is the head 26A<sub>1</sub>, 26B<sub>1</sub>Head 26A at a position separated from each other by the same distance in the + Y direction.<sub>1</sub>, 26B<sub>1</sub>Is arranged on the same plane as. In addition, head 26A<sub>1</sub>, 26B<sub>1</sub>Head 26A with respect to the above measurement axis on the same plane as<sub>2</sub>, 26B<sub>2</sub>In contrast to the head 26A<sub>1</sub>, 26B<sub>1</sub>A pair of heads 26A at positions separated from each other by the same distance in the Y direction.<sub>3</sub>, 26B<sub>3</sub>Is placed. The above 3 pairs of heads 26A<sub>1</sub>, 26B<sub>1</sub>, 26A<sub>2</sub>, 26B<sub>2</sub>, 26A<sub>3</sub>, 26B<sub>3</sub>Is fixed to the reticle base 36 via support members (not shown).
0025Further, on the -X side of the moving scale 24A on the upper surface of the reticle stage RST, a moving scale 28 having the Y-axis direction as the longitudinal direction is arranged side by side with the moving scale 24A. It is fixed to RST. The moving scale 28 is made of the same material as the moving scales 24A and 24B (for example, ceramics or glass with low thermal expansion), and a reflective diffraction grating having a periodic direction in the X-axis direction is Y on the upper surface thereof. It is formed over almost the entire length in the axial direction.
0026Above the moving scale 28 (+ Z side), as shown in FIG. 2, two heads 26C for X-axis position measurement facing the moving scale 28.<sub>1</sub>, 26C<sub>2</sub>Is placed (see Figure 1). Of these, head 26C<sub>1</sub>Is located approximately on a straight line (measurement axis) in the X-axis direction passing through the center of the above-mentioned illumination region IAR. Also, head 26C<sub>2</sub>Is the head 26C<sub>1</sub>Head 26A separated from the head in the + Y direction by a predetermined distance<sub>2</sub>At a position near the head 26A<sub>1</sub>, 26A<sub>2</sub>Etc. are arranged on the same surface.
0027In addition, head 26C<sub>1</sub>Head 26C with respect to the above measurement axis on the same plane as<sub>2</sub>In contrast to the head 26C<sub>1</sub>Head 26C at a position separated by a predetermined distance from-Y direction<sub>3</sub>Is placed. The above three heads 26C<sub>1</sub>, 26C<sub>2</sub>, 26C<sub>3</sub>Is fixed to the reticle base 36 via support members (not shown). In this embodiment, nine heads 26A<sub>1</sub>~ 26A<sub>3</sub>, 26B<sub>1</sub>~ 26B<sub>3</sub>, 26C<sub>1</sub>~ 26C<sub>3</sub>Is fixed to the reticle base 36 via a support member (not shown), but the present invention is not limited to this, and may be provided to, for example, a frame member installed on the floor surface F or the base plate BS via a vibration isolation mechanism. ..
0028In this embodiment, the head 26A<sub>1</sub>, 26B<sub>1</sub>A pair of Y linear encoders that measure the position (Y position) of the reticle stage RST in the Y-axis direction are configured by the moving scales 24A and 24B that face each other. In the following, for convenience, these Y linear encoders are used with the same code as their respective heads, and the Y linear encoder 26A is used below.<sub>1</sub>, 26B<sub>1</sub>Describe as.
0029Y linear encoder 26A<sub>1</sub>, 26B<sub>1</sub>The measurement axis of is at the same distance in the X-axis direction from the center of the above-mentioned illumination region IAR (in this embodiment, it corresponds to the optical axis AX of the projection optical system PL). Encoder 26A<sub>1</sub>, 26B<sub>1</sub>The Y position of the reticle stage RST is measured based on the average value of the measured values of. That is, Y linear encoder 26A<sub>1</sub>And 26B<sub>1</sub>The actual measurement axis for measuring the position information of the reticle stage RST by the above passes on the optical axis AX of the projection optical system PL. Therefore, during exposure, the Y position of the reticle stage RST is set to the Y linear encoder 26A.<sub>1</sub>, 26B<sub>1</sub>It is possible to measure without Abbe error by using. In addition, Y linear encoder 26A<sub>1</sub>, 26B<sub>1</sub>The rotation information (yaw) of the reticle stage RST in the θz direction is measured based on the measured value of.
0030Similarly, head 26A<sub>2</sub>, 26A<sub>3</sub>A Y linear encoder that measures the Y position of the reticle stage RST is configured by the moving scale 24A facing these. Similarly, head 26B<sub>2</sub>, 26B<sub>3</sub>And the moving scale 24B facing them constitutes a Y linear encoder that measures the Y position of the reticle stage RST. In the following, for convenience, these Y linear encoders are used with the same code as their respective heads, and the Y linear encoder 26A is used below.<sub>2</sub>, 26A<sub>3</sub>, 26B<sub>2</sub>, 26B<sub>3</sub>Describe as.
0031Also, head 26C<sub>1</sub>And the moving scale 28 facing this measure the position (X position) of the reticle stage RST in the X-axis direction on a straight line (measurement axis) parallel to the X-axis direction passing through the center of the above-mentioned illumination region IAR. An X linear encoder is configured. In the following, for convenience, this X linear encoder will be used with the same code as its head, and the X linear encoder 26C will be used.<sub>1</sub>Describe as. Therefore, at the time of exposure, the X position of the reticle stage RST is the X linear encoder 26C.<sub>1</sub>It is possible to measure without Abbe error by using.
0032Similarly, head 26C<sub>2</sub>, 26C<sub>3</sub>And the moving scale 28 constitute an X linear encoder that measures the X position of the reticle stage RST. In the following, for convenience, these X linear encoders will be referred to as the X linear encoder 26C using the same code as their respective heads.<sub>2</sub>, 26C<sub>3</sub>Describe as.
0033The above 9 linear encoders (hereinafter, also referred to as "encoders" as appropriate) 26A<sub>1</sub>~ 26C<sub>3</sub>The measured value of is sent to the main controller 20 (see Fig. 1) (see Fig. 6).
0034The lengths of the three moving scales 24A, 24B, and 28 described above in the Y-axis direction (the moving scales 24A and 24B correspond to the formation range of the diffraction grating, and the moving scale 28 corresponds to the width of the diffraction grating) are at least the reticle R1. Covers the entire area of the movement stroke (movement range) of the reticle stage RST in the Y-axis direction when the wafer W is scanned and exposed via R2 (in the present embodiment, at least during scanning exposure and before and after scanning exposure). During the acceleration / deceleration and synchronous settling of stage RST, for example, a set of three heads 26A<sub>i</sub>, 26B<sub>i</sub>, 26C<sub>i</sub>Of (i = 1 to 3), at least one set of heads (measurement beams) is set so as not to deviate from the corresponding moving scale (diffraction grating), that is, to not become unmeasurable). Similarly, the widths of the three moving scales 24A, 24B, and 28 in the X-axis direction (corresponding to the width of the diffraction grating on the moving scales 24A and 24B and the formation range of the diffraction grating on the moving scale 28) are also the same. Covers the entire area of the movement stroke in the X-axis direction (in this embodiment, for example, a set of three heads 26A<sub>i</sub>, 26B<sub>i</sub>, 26C<sub>i</sub>Of (i = 1 to 3), at least one set of heads (measurement beams) is set so as not to deviate from the corresponding moving scale (diffraction grating), that is, to not become unmeasurable). Since the reticle stage RST can rotate minutely in the θz direction, this rotation naturally causes at least three linear encoders 26A.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>The above-mentioned three movement scales 24A, 24B, and 28 are set in size (length, width) in the X-axis and Y-axis directions in consideration of the rotation range in the θz direction so that measurement by There is.
0035Further, in the present embodiment, six linear encoders 26A are used for scanning exposure using the reticle R2.<sub>1</sub>, 26A<sub>2</sub>, 26B<sub>1</sub>, 26B<sub>2</sub>, 26C<sub>1</sub>, 26C<sub>2</sub>This makes it possible to measure the position information of the reticle stage RST (including at least the position in the X-axis and Y-axis directions and the rotation information in the θz direction). In addition, six linear encoders 26A are used for scanning exposure using the reticle R1.<sub>1</sub>, 26A<sub>3</sub>, 26B<sub>1</sub>, 26B<sub>3</sub>, 26C<sub>1</sub>, 26C<sub>3</sub>This makes it possible to measure the position information of the reticle stage RST (including at least the position in the X-axis and Y-axis directions and the rotation information in the θz direction). Further, in the present embodiment, the reticle R1 and R2 are exchanged on the + Y side or the -Y side with respect to the above-mentioned illumination area IAR, or the reticle R1 is exchanged on the -Y side and the reticle R2 is exchanged on the + Y side. At least three linear encoders 26A at this exchange position<sub>2</sub>, 26B<sub>2</sub>, 26C<sub>2</sub>Or linear encoder 26A<sub>3</sub>, 26B<sub>3</sub>, 26C<sub>3</sub>It is possible to measure the position information of the reticle stage RST.
0036In this embodiment, three moving scales 24A, 24B, 28 and nine heads 26A<sub>1</sub>~ 26A<sub>3</sub>, 26B<sub>1</sub>~ 26B<sub>3</sub>, 26C<sub>1</sub>~ 26C<sub>3</sub>The encoder system for the reticle stage RST is configured by the head unit having the above, but the encoder system is not limited to the configuration shown in Fig. 2. For example, the head unit has three heads 26A.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>You may just have. In this case, the linear encoder 26A is on the way to the above reticle replacement position or its replacement position.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>When the position measurement of the reticle stage RST becomes impossible, for example, the position measurement of the reticle stage RST may be performed using another measuring device or at least a part of the above-mentioned reticle interferometer system. Further, in the present embodiment, the three moving scales 24A, 24B, and 28 are fixed to the reticle stage RST by a suction mechanism or a leaf spring, but the present invention is not limited to this, and for example, screwing or directly attaching the diffraction grating to the reticle stage. It may be formed in RST. Further, in the present embodiment, the moving scales 24A, 24B, and 28 are provided on the upper surface (illumination system side) of the reticle stage RST, but may be provided on the lower surface (projection optical system side) of the reticle stage RST, or the above-mentioned head. The arrangement of the unit (encoder head) and the moving scales 24A, 24B, 28 may be reversed, that is, the above-mentioned head unit may be provided on the reticle stage RST, and the moving scales 24A, 24B, 28 may be provided on the body side.
0037The reticle interferometer system includes a reticle Y interferometer 16y and a reticle X interferometer 16x, as shown in FIGS. 2 and 6.
0038The reticle X interferometer 16x includes a sensor head 19A (not shown in FIG. 1) and an optical system unit 19B fixed to the + X end face of the reticle stage RST, as shown in FIG.
0039The sensor head 19A is fixed to the upper surface of the reticle base 36, and contains a light source, an optical system, two analyzers (polarizers), two photoelectric conversion elements, and the like. As a light source, a dual-frequency laser utilizing the Zeeman effect is used. The cross-sectional shape of the laser beam from this light source is enlarged in the horizontal direction by the optical system, and as shown in FIG. 2, the beam BM having the enlarged cross-sectional shape is output from the sensor head 19A. Then, the beam BM is split into two in the optical system unit 19B, and one split beam is incident on a first beam splitter (not shown) and the measurement beam BM is generated.<sub>1</sub>And the reference beam, divided into the measurement beam BM<sub>1</sub>Is reflected by the reflecting surface of the plane mirror 21, and the reference beam is reflected by, for example, the reflecting surface of the reticle stage RST, returns to the first beam splitter, is coaxially combined, and is output from the optical system unit 19B. Similarly, the other split beam is incident on a second beam splitter (not shown) and the measurement beam BM<sub>2</sub>And the reference beam, divided into the measurement beam BM<sub>2</sub>Is reflected by the reflecting surface of the plane mirror 21, and the reference beam is reflected by, for example, the reflecting surface of the reticle stage RST, returns to the second beam splitter, is coaxially combined, and is output from the optical system unit 19B. Although not shown, in the present embodiment, the plane mirror 21 is fixed to a part of the body BD described above, for example, the reticle base 36 of the second column 34 or the lens barrel surface plate (main frame) 38 of the first column 32 described later. Has been done.
0040Further, the sensor head 19A receives return light from each of the first and second beam splitters in the optical system unit 19B (the measurement beam BM described above).<sub>1</sub>, BM<sub>2</sub>And the combined light with each reference beam) is returned. Inside the sensor head 19A, these return lights are incident on individual detectors via the optical system, and the interference light output from each detector is individually received by the two photoelectric conversion elements, and each interference occurs. An interference signal corresponding to light is sent to a signal processing system (not shown). This signal processing system is generated by the phase change by utilizing the fact that the phase of the measurement beam is Doppler-shifted with respect to the phase of the reference beam based on the interference signal from each photoelectric conversion element and the phase change occurs. Heterodyne detection of changes in the interference signal. Then, the signal processing system determines the measurement beam BM from the change in the detected interference signal.<sub>1</sub>, BM<sub>2</sub>Position information in the X-axis direction with respect to the plane mirror 21 at the irradiation point of<sub>1</sub>, BM<sub>2</sub>The X position information of the reticle stage RST at the irradiation point of is constantly detected with a resolution of, for example, about 0.5 to 1 nm.
0041The reticle Y interferometer 16y is a Michelson-type heterodyne laser interferometer that uses a dual-frequency laser that utilizes the Zeeman effect as a light source, similar to the reticle X interferometer 16x. In this reticle Y interferometer 16y, the Y position of the reticle stage RST was fixed to the reticle stage RST with reference to the fixed mirror 14 (see FIG. 1) fixed to the side surface of the lens barrel 40 constituting the projection unit PU. It is always detected through a moving mirror (plane mirror, retroreflector, etc.) 15 with a resolution of, for example, about 0.5 to 1 nm. At least a part of the reticle Y interferometer 16y (for example, an optical unit excluding the light source) is fixed to, for example, the reticle base 36.
0042The two-axis X position information from the reticle X interferometer 16x and the Y position information from the reticle Y interferometer 16y are sent to the main controller 20 (see FIG. 6).
0043The above-mentioned reticle interferometer system is provided with an X interferometer 16x having a sensor head 19A and an optical system unit 19B provided on the reticle stage RST, but the configuration of the X interferometer 16x is not limited to this. For example, the optical system unit 19B and the plane mirror 21 are arranged in the opposite direction, that is, the optical system unit 19B arranged on the reticle base 36 on the reflection surface (corresponding to the plane mirror 21) formed on the side surface of the reticle stage RST in the Y-axis direction. It may be configured to irradiate the measurement beam from. Further, although the sensor head 19A is provided on the reticle base 36, for example, at least a part thereof may be provided on a frame member different from the body BD. Further, in the present embodiment, as the interferometer reflecting surface of the reticle interferometer system, the above-mentioned moving mirror 15 fixed to the end of the reticle stage RST is used, but instead, for example, the reticle stage RST A reflective surface obtained by mirror-processing the end surface (side surface) may be used. Further, in the present embodiment, the Y interferometer 16y has one length measuring axis and the X interferometer 16x has two length measuring axes. For example, the number of length measuring axes is in the X-axis direction and the Y axis. The direction may be opposite, or two or more of each may be used. In particular, in the latter case, the rotation information (pitching) of the reticle stage RST in the θx direction may be measured by the Y interferometer 16y, and the rotation information (rolling) of the reticle stage RST in the θy direction may be measured by the X interferometer 16x.
0044In the exposure apparatus 100 of the present embodiment, the measured values of the reticle interferometer systems 16x and 16y are measured by the encoder 26A, which will be described later.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>It is used only when calibrating the measured values such as, etc., and during the exposure operation, the position of the reticle stage RST is controlled based on the measured values of the encoder system on the reticle side. In particular, the position of the reticle stage RST during scanning exposure is the encoder 26A.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>It is managed by the main controller 20 based on the measured value of. Therefore, as can be easily imagined from FIG. 2, it is necessary to switch the encoder (connecting the measured values) used for the position control of the reticle stage RST in the exposure operation, which will be described later.
0045Above the reticle stage RST, light of an exposure wavelength was used to simultaneously detect a pair of reference marks on the wafer stage WST and a pair of reticle marks on the corresponding reticle via the projection optical system PL. A pair of reticle alignment systems 13A and 13B (not shown in FIG. 1, see FIG. 6) composed of a TTR (Through The Reticle) type alignment system are provided at predetermined distances in the X-axis direction. As the pair of reticle alignment systems 13A and 13B, those having the same configuration as those disclosed in, for example, Japanese Patent Application Laid-Open No. 7-176468 (corresponding US Pat. No. 5,646,413) can be used.
0046The projection unit PU is held in a part of the body BD at the lower part of FIG. 1 of the reticle stage RST. This body BD includes a first column 32 provided on a frame caster FC installed on the floor surface F of a clean room, and a second column 34 fixed on the first column 32.
0047The frame caster FC includes a base plate BS placed horizontally on the floor surface F and a plurality of, for example, three (or four) legs 39 fixed on the base plate BS (however, the depth of the paper in FIG. 1). The side leg is provided with (not shown).
0048The first column 32 is substantially horizontal by a plurality of, for example, three (or four) first anti-vibration mechanisms 58 individually fixed to the upper ends of the plurality of legs 39 constituting the frame caster FC. It is equipped with a lens barrel surface plate (mainframe) 38 supported by.
0049A circular opening (not shown) is formed in the lens barrel surface plate 38 at a substantially central portion thereof, a projection unit PU is inserted into the circular opening from above, and the projection unit PU inserts a flange FLG provided on the outer peripheral portion thereof. It is held by the lens barrel surface plate 38 via the lens barrel. On the upper surface of the lens barrel surface plate 38, one end (lower end) of a plurality of, for example, three legs 41 (however, the legs on the back side of the paper in FIG. 1 are not shown) is fixed at a position surrounding the projection unit PU. ing. The other end (upper end) surface of each of these legs 41 is on substantially the same horizontal plane, and the above-mentioned reticle base 36 is fixed to these legs 41. In this way, the reticle base 36 is horizontally supported by the plurality of legs 41. That is, the second column 34 is composed of the reticle base 36 and the plurality of legs 41 supporting the reticle base 36. The reticle base 36 has an opening 36a formed in the center thereof, which serves as a passage for the illumination light IL.
0050The projection unit PU includes a lens barrel 40 that is cylindrical and provided with the flange FLG, and a projection optical system PL composed of a plurality of optical elements held in the lens barrel 40. In the present embodiment, the projection unit PU is placed on the lens barrel surface plate 38, but as disclosed in, for example, International Publication No. 2006/038952, the projection unit PU is not shown above the projection unit PU. The projection unit PU may be suspended and supported by the main frame member of the above, the reticle base 36, or the like.
0051As 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. This projection optical system PL has a predetermined projection magnification (for example, 1/4 times or 1/5 times) by telecentric on both sides, for example. Therefore, when the illumination region IAR is illuminated by the illumination light IL from the illumination system 10, the reticle (R1 or R2) is arranged so that the first surface (object surface) of the projection optical system PL and the pattern surface almost coincide with each other. Due to the illumination light IL that has passed through, a reduced image of the circuit pattern of the reticle in the illumination area IAR (a reduced image of a part of the circuit pattern) is moved to the second surface (image surface) side via the projection optical system PL. It is formed in a region (exposure region) conjugate to the illumination region IAR on the wafer W on which a resist (sensitizer) is coated on the surface to be arranged. Then, by synchronously driving the reticle stage RST and the wafer stage WST, the reticle is moved relative to the illumination region IAR (illumination light IL) in the scanning direction (Y-axis direction), 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.
0052The wafer stage apparatus 12 is mounted on a stage base 71, which is supported substantially horizontally by a plurality of (for example, three or four) second anti-vibration mechanisms (not shown) arranged on the base plate BS. It includes an arranged wafer stage WST, a wafer stage drive system 27 for driving the wafer stage WST, and the like.
0053The stage base 71 is made of a plate-shaped member also called a surface plate, and its upper surface is finished with extremely high flatness, and is used as a guide surface when the wafer stage WST is moved.
0054The wafer stage WST has a main body portion and a table portion above the main body portion, and the wafer stage drive system 27 including, for example, a linear motor, a voice coil motor, and the like has an X-axis direction, a Y-axis direction, a Z-axis direction, and a θx direction. It is driven in 6 degrees of freedom in the θy and θz directions.
0055As the wafer stage WST, for example, a wafer stage main body driven by a linear motor or the like in at least the X-axis direction, the Y-axis direction, and the θz direction, and a voice coil motor or the like on the wafer stage main body at least in the Z-axis direction, θx. A structure including a wafer table that is micro-driven in the direction and the θy direction may be adopted.
0056A wafer W is placed on the wafer stage WST (more accurately, on the table portion) via a wafer holder (not shown), and the wafer W is fixed to the wafer holder by, for example, vacuum adsorption (or electrostatic adsorption). Has been done.
0057The position information of the wafer stage WST in the XY plane (moving surface) is the encoder system including the head units 46B, 46C, 46D and the moving scales 44B, 44C, 44D, etc., and the wafer laser interferometer system shown in FIG. It is configured to be measurable by 18 (hereinafter referred to as "wafer interferometer system"). Hereinafter, the configuration and the like of the encoder system for the wafer stage WST and the wafer interferometer system 18 will be described in detail.
0058As shown in FIG. 3, four moving scales 44A to 44D are fixed on the upper surface of the wafer stage WST so as to surround the wafer W. More specifically, the moving scales 44A to 44D are made of the same material (for example, ceramics or glass with low thermal expansion), and a reflective diffraction grating having a longitudinal direction as a periodic direction is formed on the surface thereof. .. This diffraction grating is formed, for example, at a pitch between 4 μm and 138 nm, and in this embodiment, at a pitch of 1 μm. In FIG. 3, for convenience of illustration, the grid pitch is shown to be much wider than the actual pitch. The same applies to other figures.
0059The moving scales 44A and 44C have a longitudinal direction that coincides with the Y-axis direction in FIG. 3, and is symmetrical with respect to a center line parallel to the Y-axis direction that passes through the center of the wafer stage WST (excluding the moving mirrors 17X and 17Y). Each diffraction grating that is arranged and formed on the moving scales 44A and 44C is also arranged symmetrically with respect to its center line. Since the diffraction gratings are periodically arranged in the Y-axis direction, these moving scales 44A and 44C are used for measuring the position of the wafer stage WST in the Y-axis direction.
0060In addition, the moving scales 44B and 44D have a longitudinal direction that coincides with the X-axis direction in FIG. 3, and a center line parallel to the X-axis direction that passes through the center of the wafer stage WST (excluding the moving mirrors 17X and 17Y). The diffraction gratings arranged symmetrically and formed on the moving scales 44B and 44D are also arranged symmetrically with respect to the center line. Since the diffraction gratings are periodically arranged in the X-axis direction, these moving scales 44B and 44D are used for measuring the position of the wafer stage WST in the X-axis direction.
0061Note that FIG. 1 shows a state in which the wafer W is exposed above the moving scale 44C. This is for convenience, and in reality, the upper surface of the moving scales 44A to 44D is a wafer. It is located at about the same height as or above the upper surface of W.
0062On the other hand, as can be seen from FIGS. 1 and 3, four encoder head units (hereinafter abbreviated as "head units") 46A to 46D are arranged so as to surround the lowermost end of the projection unit PU from all sides. They are arranged so as to intersect with the corresponding movement scales 44A to 44D. Although these head units 46A to 46D are not shown in FIG. 1 from the viewpoint of avoiding complications in the drawings, they are actually fixed to the lens barrel surface plate 38 in a suspended state via a support member. ..
0063The head units 46A and 46C have the X-axis direction orthogonal to the longitudinal direction (Y-axis direction in FIG. 3) of the corresponding moving scales 44A and 44C on the -X side and + X side of the projection unit PU as the longitudinal direction. Moreover, they are arranged symmetrically with respect to the optical axis AX of the projection optical system PL. Further, the head units 46B and 46D are oriented in the Y-axis direction orthogonal to the longitudinal direction (X-axis direction in FIG. 3) of the corresponding moving scales 44B and 44D on the + Y side and -Y side of the projection unit PU, respectively. And are arranged symmetrically with respect to the optical axis AX of the projection optical system PL.
0064Each of the head units 46A to 46D may have, for example, a single head or a plurality of heads arranged almost seamlessly, but in the present embodiment, the head unit 46C is typically shown in FIG. As described above, it has a plurality of heads 48a to 48k arranged at predetermined intervals along the longitudinal direction thereof, for example, 11 heads. The head units 46A to 46D are intervals that do not deviate from the corresponding moving scales (diffraction gratings) of the two adjacent heads, in other words, the diffraction gratings in the direction orthogonal to the longitudinal direction of the moving scales (diffraction grating arrangement direction). A plurality of heads are arranged at intervals equal to or less than the width of.
0065The head unit 46A, together with the moving scale 44A, constitutes a multi-lens, more accurately 11-eye Y linear encoder 50A (see FIG. 6) equipped with heads 48a to 48k that measure the Y position of the wafer stage WST. The head unit 46B, together with the moving scale 44B, constitutes an 11-eye X linear encoder 50B (see FIG. 6) that measures the X position of the wafer stage WST. The head unit 46C, together with the moving scale 44C, constitutes an 11-eye Y linear encoder 50C (see FIG. 6) that measures the Y position of the wafer stage WST. The head unit 46D, together with the moving scale 44D, constitutes an 11-eye X linear encoder 50D (see FIG. 6) that measures the X position of the wafer stage WST. The measured values of the encoders 50A to 50D are supplied to the main controller 20. In the present embodiment, the four head units 46A to 46D are suspended and supported by the lens barrel platen 38, but the exposure device 100 in FIG. 1 projects the four head units 46A to 46D onto the mainframe member or the reticle base 36 as described above. When the unit PU is suspended and supported, for example, the head units 46A to 46D may be suspended and supported integrally with the projection unit PU, or from the mainframe member or the reticle base 36 independently of the projection unit PU. Four head units 46A to 46D may be provided on the measurement frame that is suspended and supported.
0066Further, as shown in FIG. 1, the position information of the wafer stage WST has a resolution of, for example, about 0.5 to 1 nm by the wafer interferometer system 18 that irradiates the moving mirrors 17 and 43 fixed to the wafer stage WST with the measurement beam. Is always detected in. At least a part of the wafer interferometer system 18 (for example, an optical unit excluding a light source) is fixed to a lens barrel surface plate 38 in a suspended state. At least a part of the wafer interferometer system 18 may be suspended and supported integrally with the projection unit PU, or may be provided in the measurement frame described above.
0067Here, on the wafer stage WST, as shown in FIG. 3, a Y moving mirror 17Y having a reflecting surface orthogonal to the Y-axis direction which is the scanning direction and an X-axis direction which is the non-scanning direction are actually present. An X moving mirror 17X having a reflecting surface orthogonal to the above is provided, and in FIG. 1, these are typically shown as the moving mirror 17.
0068The wafer interferometer system 18 includes a wafer Y interferometer 18Y and two wafer X interferometers 18X, as shown in FIG.<sub>1</sub>And 18X<sub>2</sub>And two Z interferometers 18Z<sub>1</sub>, 18Z<sub>2</sub>Includes 5 interferometers. These 5 interferometers 18Y, 18X<sub>1</sub>, 18X<sub>2</sub>, 18Z<sub>1</sub>, 18Z<sub>2</sub>As, a Michelson-type heterodyne laser interferometer using a dual-frequency laser utilizing the Zeeman effect is used. Of these, the wafer Y interferometer 18Y is an axis parallel to the Y axis passing through the optical axis AX (center of the above-mentioned exposure region) of the projection optical system PL and the detection center of the alignment system ALG, as shown in FIG. A multi-axis interferometer having a plurality of length measuring axes including two length measuring axes symmetrical with respect to (central axis) is used.
0069Wafer X interferometer 18X<sub>1</sub>Irradiates the moving mirror 17X with a measurement beam along the length measurement axis parallel to the X axis, which passes through the optical axis AX of the projection optical system PL. This wafer X interferometer 18X<sub>1</sub>Measures the position information of the reflecting surface of the moving mirror 17X with reference to the reflecting surface of the X fixed mirror fixed to the side surface of the lens barrel 40 of the projection unit PU as the X position of the wafer stage WST.
0070Wafer X interferometer 18X<sub>2</sub>Irradiates the moving mirror 17X with a measurement beam along the length measurement axis parallel to the X axis, which passes through the detection center of the alignment system ALG, and refers to the reflection surface of the fixed mirror fixed to the side surface of the alignment system ALG. The position information of the reflecting surface of the moving mirror 17X is measured as the X position of the wafer stage WST.
0071Further, as shown in FIGS. 1 and 4, a moving mirror 43 having a longitudinal direction in the X-axis direction is provided on the + Y side of the main body of the wafer stage WST via a kinematic support mechanism (not shown). Is attached.
0072A pair of Z interferometers 18Z that form part of the interferometer system 18 that irradiate the moving mirror 43 with a measurement beam facing the moving mirror 43.<sub>1</sub>, 18Z<sub>2</sub>Is provided (see Figures 3 and 4). More specifically, as can be seen from FIGS. 3 and 4, the moving mirror 43 has a length in the X-axis direction longer than that of the moving mirror 17Y, and has a hexagonal shape as if a rectangle and an isosceles trapezium were integrated. It is composed of a member having a cross-sectional shape of. The surface on the + Y side of the moving mirror 43 is mirror-finished to form the three reflecting surfaces 43b, 43a, and 43c shown in FIG.
0073The reflecting surface 43a constitutes an end surface on the + Y side of the moving mirror 43, and extends parallel to the XZ plane and in the X-axis direction. The reflecting surface 43b constitutes a surface adjacent to the + Z side of the reflecting surface 43a, and extends parallel to the surface inclined in the clockwise direction in FIG. 4 and in the X-axis direction by a predetermined angle with respect to the XZ plane. The reflecting surface 43c constitutes a surface adjacent to the -Z side of the reflecting surface 43a, and is provided symmetrically with the reflecting surface 43b with the reflecting surface 43a interposed therebetween.
0074The Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>Are located approximately the same distance on one side and the other side of the Y interferometer 18Y in the X-axis direction, and at positions slightly lower than the Y interferometer 18Y, as can be seen from FIGS. 3 and 4.
0075Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>Projects the measurement beams B1 and B2 onto the reflection surfaces 43b and 43c, respectively, along the Y-axis direction, as shown in FIGS. 3 and 4. In the present embodiment, it has a fixed mirror 47A having a reflecting surface on which the measurement beam B1 reflected by the reflecting surface 43b is incident substantially vertically, and a reflecting surface on which the measuring beam B2 reflected by the reflecting surface 43c is incident substantially vertically. Fixed mirrors 47B are extended in the X-axis direction, respectively.
0076The fixed mirrors 47A and 47B are supported by, for example, the same support (not shown) provided on the lens barrel surface plate 38. The fixed mirrors 47A and 47B may be supported by the above-mentioned measurement frame or the like.
0077As shown in FIG. 3, the Y interferometer 18Y is located at the same distance 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 to the -X side and + X side. Measurement beam B4 along the length measurement axis in the distant Y-axis direction<sub>1</sub>, B4<sub>2</sub>Is projected onto the moving mirror 17Y, and by receiving the reflected light of each, the measurement beam B4<sub>1</sub>, B4<sub>2</sub>The position information of the wafer stage WST in the Y-axis direction at the irradiation point of is detected with reference to the reflection surface of the Y-fixed mirror fixed to the side surface of the lens barrel 40 of the projection unit PU. In FIG. 4, the measurement beam B4<sub>1</sub>, B4<sub>2</sub>Is typically shown as the measurement beam B4.
0078In addition, the Y interferometer 18Y measures the beam B4 in plan view.<sub>1</sub>, B4<sub>2</sub>Measured beam B4 in side view, located approximately in the center of<sub>1</sub>, B4<sub>2</sub>The measurement beam B3 is projected toward the reflection surface 43a of the fixed mirror 43 along the length measurement axis in the Y-axis direction located on the -Z side of the mirror 43, and moves by receiving the measurement beam B3 reflected by the reflection surface 43a. The position information of the reflecting surface 43a (that is, the wafer stage WST) of the mirror 43 in the Y-axis direction is detected.
0079The main controller 20 is the measurement beam B4 of the Y interferometer 18Y.<sub>1</sub>, B4<sub>2</sub>The Y position of the moving mirror 17Y, that is, the wafer table WTB (wafer stage WST) is calculated based on the average value of the measured values on the length measurement axis corresponding to. Further, the main control device 20 calculates the displacement (pitching amount) of the wafer stage WST in the θx direction based on the Y position of the moving mirror 17Y and the moving mirror 43 on the reflecting surface 43a.
0080Also, Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>The measurement beams B1 and B2 projected from are incident on the reflecting surfaces 43b and 43c of the moving mirror 43 at a predetermined angle of incidence (referred to as θ / 2), and are reflected by the reflecting surfaces 43b and 43c to be reflected by the fixed mirror 47A. , 47B incident perpendicular to the reflective surface. Then, the measurement beams B1 and B2 reflected by the fixed mirrors 47A and 47B are reflected again by the reflecting surfaces 43b and 43c, respectively, and the Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>Is received by.
0081Here, assuming that the displacement (movement amount) of the wafer stage WST (that is, the moving mirror 43) in the Y-axis direction is ΔYo and the displacement (movement amount) in the Z-axis direction is ΔZo, the Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>The optical path length change ΔL1 of the measurement beam B1 and the optical path length change ΔL2 of the measurement beam B2 received in the above are represented by the following equations (1) and (2), respectively.
0082ΔL1 ΔYo × cosθ-ΔZo × sinθ ... (1) ΔL2 ΔYo × cosθ + ΔZo × sinθ ... (2) Therefore, from equations (1) and (2), ΔZo and ΔYo can be obtained by the following equations (3) and (4).
0083ΔZo = (ΔL2-ΔL1) / 2sinθ ... (3) ΔYo = (ΔL1 + ΔL2) / 2cosθ ... (4)
0084The above displacements ΔZo and ΔYo are the Z interferometer 18Z.<sub>1</sub>, 18Z<sub>2</sub>It is required in each of. Therefore, Z interferometer 18Z<sub>1</sub>Let ΔZoR and ΔYoR be the displacements obtained by, and Z interferometer 18Z.<sub>2</sub>If the displacements obtained in are ΔZoL and ΔYoL and the distances (intervals) of the measurement beams B1 and B2 in the X-axis direction are D (see Fig. 3), the displacement of the moving mirror 43 (that is, the wafer stage WST) in the θz direction (that is, the wafer stage WST) The yawing amount) Δθz and the displacement (rolling amount) Δθy of the moving mirror 43 (that is, the wafer stage WST) in the θy direction are obtained by the following equations (5) and (6).
0085Δθz = (ΔYoR-ΔYoL) / D ... (5) Δθy = (ΔZoL-ΔZoR) / D ... (6) Therefore, the main controller 20 uses the above equations (1) 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.
0086Further, as described above, the main controller 20 obtains the displacement ΔY of the wafer stage WST in the Y-axis direction and the displacement (pitching amount) Δθx in the θx direction of the wafer stage WST from the measurement results of the Y interferometer 18Y. Can be done.
0087In Fig. 1, the X interferometer 18X<sub>1</sub>, 18X<sub>2</sub>And Y interferometer 18Y, and Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>Is typically shown as a wafer interferometer system 18, and a fixed mirror for X-axis position measurement and a fixed mirror for Y-axis position measurement are typically shown as fixed mirror 57. Further, the alignment system ALG and the fixed mirror fixed to the alignment system ALG are not shown in FIG.
0088In this embodiment, the wafer X interferometer 18X<sub>1</sub>And the wafer Y interferometer 18Y are used to calibrate the encoder system used during wafer exposure operation, and the wafer X interferometer 18X.<sub>2</sub>And the wafer Y interferometer 18Y are used when the mark is detected by the alignment system ALG. In addition to the Y position of the wafer stage WST, the wafer Y interferometer 18Y can also measure rotation information (pitching) in the θx direction. In this embodiment, the X interferometer 18X of the above-mentioned wafer interferometer system 18<sub>1</sub>, 18X<sub>2</sub>As the reflecting surface of the measurement beam of the Y interferometer 18Y, the moving mirrors 17X and 17Y fixed to the wafer stage WST were used, but the present invention is not limited to this, and for example, the end surface (side surface) of the wafer stage WST is mirror-processed. A reflective surface (corresponding to the reflective surface of the moving mirrors 17X and 17Y) may be formed.
0089Wafer Y Interferometer 18Y, Wafer X Interferometer 18X<sub>1</sub>And 18X<sub>2</sub>, And Z interferometer 18Z<sub>1</sub>And 18Z<sub>2</sub>The measured value of is supplied to the main controller 20.
0090Further, on the wafer stage WST, a reference mark plate (not shown) is fixed in a state where the surface thereof is at the same height as the wafer W. On the surface of this reference mark plate, at least a pair of first reference marks for reticle alignment and a second reference mark for baseline measurement of an alignment system ALG having a known positional relationship with respect to these first reference marks. Etc. are formed.
0091In the exposure apparatus 100 of the present embodiment, although not shown in FIG. 1, an irradiation system similar to that disclosed in, for example, Japanese Patent Application Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332) is used. A oblique incident multipoint focal position detection system consisting of 42a and a light receiving system 42b (see Fig. 6) is provided.
0092Further, in the exposure apparatus 100, the above-mentioned alignment system ALG (not shown in FIG. 1) is provided in the vicinity of the projection unit PU. As this alignment system ALG, for example, an image processing type alignment sensor, a so-called FIA (Field Image Alignment) system, is used. This off-axis alignment system ALG supplies the position information of the mark with reference to the index center to the main control device 20. The main controller 20 uses this supplied information and the interferometers 18Y and 18X of the wafer interferometer system 18.<sub>2</sub>Interferometers 18Y, 18X of the mark to be detected, specifically the second reference mark on the reference mark plate or the alignment mark on the wafer, based on the measured values of<sub>2</sub>Measure the position information on the coordinate system (alignment coordinate system) specified in.
0093Next, the configurations of the encoders 50A to 50D and the like will be described by taking the encoder 50C enlarged in FIG. 5 as a representative. In FIG. 5, one of the heads 48a to 48k (FIG. 3) of the head unit 46C that irradiates the moving scale 44C with the detection light is shown as the head 48y.
0094The head 48y is roughly divided into three parts: an irradiation system 64a, an optical system 64b, and a light receiving system 64c.
0095The 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 the laser beam LB emitted from the semiconductor laser LD. Including the lens L1.
0096The 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.
0097The light receiving system 64c includes a polarizer (photon detector), a photodetector, and the like.
0098In this encoder 50C, 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>Reached the reflective diffraction grating RG formed on the moving scale 44C through the reflection mirror R1a, and the beam LB 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.
0099Beam 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.
0100Polarization 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 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.
0101Then, 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 interference light. The interference light is detected by the photodetector, and the interference light is detected. It is converted into an electric signal according to the intensity.
0102As can be seen from the above explanation, in the encoder 50C, 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. Then, when the moving scale 44C (that is, the wafer stage WST) moves in the measurement direction (in this case, the Y-axis direction), the phases of the two beams change 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 encoder 50C. The other encoders 50A, 50B, and 50D are also configured in the same manner as the encoder 50C. Also, the nine encoders 26A for the reticle stage mentioned above.<sub>1</sub>~ 26C<sub>3</sub>Also, a diffraction interference type encoder having the same configuration as the encoder 50C is used. As each encoder, an encoder having a resolution of, for example, about 0.1 nm is used.
0103In FIG. 6, a part of the control system related to the stage control of the exposure apparatus 100 of the present embodiment is omitted and shown in a block diagram. The control system of FIG. 6 includes a so-called microcomputer (or workstation) consisting of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and covers the entire device. It is mainly composed of a main control device 20 that controls in a centralized manner.
0104In the exposure apparatus 100 configured as described above, for example, the EGA (Enhanced Global Alignment) method disclosed in Japanese Patent Application Laid-Open No. 61-44429 and the corresponding US Pat. No. 4,780,617 is used. During the wafer alignment operation, the position of the wafer stage WST is controlled by the main controller 20 based on the measured values of the wafer interferometer system 18 as described above. The position of the wafer stage WST is controlled by the main controller 20 based on the measured values of the encoders 50A to 50D. The position of the wafer stage WST may be managed based on the measured values of the encoders 50A to 50D even during the wafer alignment operation. When managing the position of the wafer stage WST based on the measured values of the encoders 50A to 50D, at least one measured value of the wafer interferometer system 18 (for example, position information in the Z-axis, θx and θy directions) is used together. You may.
0105Therefore, in the present embodiment, the position measurement system used for the position measurement of the wafer stage is used as the wafer interferometer system 18 (that is, the wafer Y interferometer 18Y and the wafer X interferometer) after the wafer alignment operation is completed and before the exposure is started. 18X<sub>2</sub>) To the encoder 50A to 50D, it is necessary to perform the switching operation of the position measurement system.
0106Hereinafter, the switching operation of this position measurement system will be briefly described.
0107When the wafer alignment is completed, for example, as shown in FIG. 7, the position of the wafer stage WST is set to the interferometers 18Y, 18X.<sub>2</sub>, 18Z<sub>1</sub>, 18Z<sub>2</sub>It is managed by the main controller 20 based on the measured value of. Therefore, after the wafer alignment is completed, the main controller 20 uses these interferometers 18Y, 18X.<sub>2</sub>, 18Z<sub>1</sub>, 18Z<sub>2</sub>The wafer stage WST is driven in the + Y direction via the wafer stage drive system 27 based on the measured values of.
0108And as shown in Figure 8, the interferometer 18X<sub>2</sub>Measurement beam from and interferometer 18X<sub>1</sub>When the wafer stage WST reaches the position where the two measurement beams from the above are simultaneously irradiated to the X moving mirror 17X, the main controller 20 rotates the wafer stage WST by θz based on the measurement value of the interferometer 18Y. After adjusting the attitude of the wafer stage WST so that the error (yawing error) (and θx rotation error (pitching error)) is zero, the interferometer 18X<sub>1</sub>The measured value of, the interferometer 18X at that time<sub>2</sub>Preset to the same value as the measured value of. The θz rotation error of the wafer stage WST is the Z interferometer 18Z.<sub>1</sub>, 18Z<sub>2</sub>It may be adjusted based on the measured value of.
0109After that preset, the main controller 20 is an interferometer 18X<sub>1</sub>, The wafer stage WST is stopped at that position for a predetermined time until the short-term fluctuation due to the air fluctuation (air temperature fluctuation) of the measured value of 18Y becomes a negligible level due to the averaging effect, and the interference acquired during the stop time. 18X in total<sub>1</sub>The added average value (average value during the stop time) of the measured values of is taken over as the measured value of the X linear encoders 50B and 50D. At the same time, the main controller 20 sets the average value of the added average values (average values during the stop time) of the measured values of the interferometer 18Y acquired during the stop time for each of the multiple axes of the Y linear encoders 50A and 50C. Take over as a measured value. As a result, the presets of the X linear encoders 50B and 50D and the Y linear encoders 50A and 50C, that is, the switching operation of the position measurement system is completed. After that, the position of the wafer stage WST will be managed by the main controller 20 based on the measured values of the encoders 50A to 50D.
0110Next, the scanning operation of the reticle stage RST for exposure, including the encoder switching (connecting the measured values) operation in the encoder system for the reticle stage, will be described.
0111For example, in the case of scan exposure by moving the wafer W in the + Y direction and moving the reticle R1 in the -Y direction (here, focusing on the moving direction of the wafer W, it is called a plus scan exposure), FIG. 9 shows. Acceleration of the reticle stage RST in the -Y direction is started from the acceleration start position. At this acceleration start position, the position of the reticle stage RST is set by the main controller 20 to the encoder 26A.<sub>2</sub>, 26B<sub>2</sub>And 26C<sub>2</sub>Is measured using.
0112Then, at the end of acceleration when the acceleration of the reticle stage RST in the -Y direction is completed, as shown in FIG. 10, the -Y end of the reticle R1 almost coincides with the + Y end of the illumination region IAR. Immediately before this, head 26A<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>However, they will face the moving scales 24A, 24B, and 28, respectively. That is, encoder 26A<sub>2</sub>, 26B<sub>2</sub>And 26C<sub>2</sub>Not only encoder 26A<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Also, the position of the reticle stage RST can be measured.
0113Therefore, the main controller 20 is, for example, the encoder 26A.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Encoder 26A at a certain point from the time when the position of the reticle stage RST became measurable to the end of acceleration by<sub>2</sub>, 26B<sub>2</sub>And 26C<sub>2</sub>Measured value (count value with a predetermined origin as zero (scale reading)), encoder 26A<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Take over as it is as the measured value of. After that, the main controller 20 is the encoder 26A.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Use to manage the position of the reticle stage RST.
0114Then, the constant velocity movement of the reticle stage RST is started from the time of FIG. 10, and the exposure is started when the predetermined settling time elapses and the pattern area of the reticle R1 reaches the illumination area IAR (see FIG. 16). ). Further, after a predetermined time has elapsed, the exposure is completed (see FIG. 17), the deceleration of the reticle stage RST is started, and the reticle stage RST is stopped at the position shown in FIG. The deceleration of the reticle stage RST may be started almost at the same time as the end of the exposure.
0115As can be seen from FIGS. 10 and 11, the reticle stage is the period from immediately before the start of exposure (that is, when the encoder used for position control of the reticle stage RST is switched) to the end of deceleration through the scanning exposure period. The position of RST is encoder 26A<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>It is managed by the main controller 20 based on the measured value of.
0116On the other hand, in the case of scan exposure (minus scan exposure) by moving the wafer W in the -Y direction and moving the reticle R1 in the + Y direction, the reticle stage starts from the state shown in FIG. Acceleration of RST in the + Y direction is started, and immediately after the end of exposure shown in Fig. 10, the encoder is switched (connection of measured values), and during the deceleration period, the position of the reticle stage RST is the encoder. 26A<sub>2</sub>, 26B<sub>2</sub>, 26C<sub>2</sub>It is managed by the main controller 20 based on the measured value of.
0117Here, in FIGS. 9, 10, 11, 11 and the like, the position of the reticle stage RST is measured by the interferometers 16x and 16y in addition to the encoder. Of course, it is not always necessary to measure the position. In this embodiment, a method of using the measurement results of the encoder and the interferometers 16x and 16y obtained during the scanning exposure will be described later.
0118Although detailed description is omitted, the encoder 26A is used for plus scan exposure and minus scan exposure using the reticle R2.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>And encoder 26A<sub>3</sub>, 26B<sub>3</sub>, 26C<sub>3</sub>And are used. At this time as well, the same encoder switching (connecting the measured values) as described above is performed, and the position of the reticle stage RST is set to the encoder 26A at least during the scanning exposure period.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>It is managed by the main controller 20 based on the measured value of. Further, the main controller 20 manages not only the X and Y positions of the reticle stage RST but also the positions (yaw) in the θz direction based on the measured values of the encoder.
0119In the exposure apparatus 100 of the present embodiment, the reticle alignment (reticle) is performed by using the reticle alignment systems 13A and 13B (Fig. 6), the reference mark plate on the wafer stage WST, the alignment system ALG, and the like in the same manner as the normal scanning stepper. A series of operations such as (including the correspondence between the coordinate system and the wafer coordinate system) and baseline measurement of the alignment system ALG are performed. The position control of the reticle stage RST and wafer stage WST during these series of operations is performed by the interferometers 16y and 16x, and the interferometer 18X.<sub>1</sub>, 18X<sub>2</sub>, 18Y, 18Z<sub>1</sub>, 18Z<sub>2</sub>It is performed based on the measured value of. Even in reticle alignment or baseline measurement, the positions of the reticle stage RST and the wafer stage WST may be controlled based only on the measured values of the encoder described above or based on the measured values of both the interferometer and the encoder.
0120Next, the main control device 20 performs wafer exchange on the wafer stage WST (loading the wafer if there is no wafer on the wafer stage WST) using a wafer loader (conveyor device) (not shown), and aligns the wafer. For example, an EGA type wafer alignment using the system ALG is performed. By this wafer alignment, the array coordinates of a plurality of shot regions on the wafer on the above-mentioned alignment coordinate system can be obtained.
0121After that, the main controller 20 switches the position measurement system described above, and then the position of the wafer stage WST is managed based on the previously measured baseline and the measured values of the encoders 50A to 50D, and the position of the wafer stage WST is managed as described above. Encoder 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>While managing the position of the reticle stage RST based on the measured value of, step-and-scan exposure is performed in the same procedure as a normal scanning stepper, and the reticle (R1 or R2) pattern is displayed on the wafer. Is transferred to each of the multiple shot regions of.
0122FIG. 12A shows a state in which the wafer stage WST is located at a position where the center of the wafer W is directly below the projection unit PU, and FIG. 12B shows an intermediate between the center and the outer periphery of the wafer W. The state where the wafer stage WST is located near the projection unit PU is shown. Further, FIG. 13 (A) shows a state in which the wafer stage WST is located at a position where the vicinity of the edge on the + Y side of the wafer W is directly below the projection unit PU, and FIG. 13 (B) shows the state of the wafer W. It is shown that the wafer stage WST is located at a position where the vicinity of the edge in the direction forming 45 ° with respect to the X-axis and the Y-axis when viewed from the center is directly below the projection unit PU. Further, FIG. 14 shows a state in which the wafer stage WST is located at a position where the vicinity of the edge on the + X side of the wafer W is directly below the projection unit PU. Looking at FIGS. 12A to 14A, in each of the head units 46A to 46D, at least one of the 11 heads (one or two in the present embodiment) corresponds to each of the head units 46A to 46D. It can be seen that it faces the moving scale. This fact, and the symmetrical arrangement in the vertical and horizontal directions around the optical axis AX of the projection optical system PL of the head units 46A to 46D, and the X-axis direction and the Y-axis direction with respect to the center of the wafer stage WST of the moving scales 44A to 44D. Considering the symmetrical arrangement of the above, we can see the following. That is, in the exposure apparatus 100, at least one of the 11 heads corresponds to each of the head units 46A to 46D regardless of the position of the wafer stage WST within the moving range of the wafer stage WST during the exposure operation. It is possible to constantly measure the X position and Y position of the wafer stage WST with four encoders 50A to 50D facing the moving scale. It is also possible to measure the yawing of the wafer stage WST.
0123In other words, each of the four moving scales 44A to 44D described above has a length (corresponding to the formation range of the diffraction grating) in the longitudinal direction, and the moving stroke of the wafer stage WST when scanning and exposing at least the entire surface of the wafer W. It covers the entire area of (movement range) (in this embodiment, in all shot regions, at least during scanning exposure and during the acceleration / deceleration and synchronous settling period of the wafer stage WST before and after scanning exposure, four head units 46A. It is set longer than the size (diameter) of the wafer W so that ~ 46D (measurement beam) does not deviate from the corresponding moving scale (diffraction grating), that is, it does not become unmeasurable).
0124Similarly, the lengths (corresponding to the detection range of the diffraction grating) of the four head units 46A to 46D in the longitudinal direction are at least the movement stroke of the wafer stage WST when the entire surface of the wafer W is scanned and exposed. Its movement covers the entire area (ie, at least during the wafer W exposure operation, the four head units 46A-46D (measurement beams) do not deviate from the corresponding movement scale (diffraction grating), that is, do not become unmeasurable). It is set to be equal to or higher than the stroke. It should be noted that the head units 46A to 46D can be used to measure the position of the wafer stage WST by the encoders 50A to 50D not only in the exposure operation but also in other operations such as alignment operation (including the above-mentioned wafer alignment and baseline measurement). It may be configured.
0125By the way, since the fixed position of the moving scale of the encoder shifts with the lapse of use time, or the pitch of the diffraction grating changes partially or entirely due to thermal expansion or the like, the encoder lacks long-term stability. Therefore, the error included in the measured value increases with the passage of use time, and it is necessary to calibrate this. Hereinafter, the encoder calibration operation performed by the exposure apparatus 100 of the present embodiment will be described.
0126First, the first calibration operation for correcting the gain error and the linearity error of the measured values of the encoders constituting the encoder system for the reticle stage will be described. Since this first calibration operation is performed, for example, before the start of exposure of the first wafer for each lot, that is, at relatively long intervals, it is also referred to as a long-term calibration operation below.
0127Specifically, the main controller 20 covers a range in which the illumination region IAR passes through the reticle R1 and R2 (pattern region) (actually, the reticle R1 and R2 (pattern region) cross the illumination region IAR). , Scan the reticle stage RST in the Y-axis direction at an extremely low speed so that short-term fluctuations in the measured values of the interferometer can be ignored. In this first calibration operation, the illumination area IAR is not illuminated by the illumination light IL, but here, in order to explain the moving position of the reticle stage RST in an easy-to-understand manner, "the illumination area IAR passes through." Expressions such as "to do" are used.
0128During the above scan, the main controller 20 uses the reticle Y interferometer 16y and the Y linear encoder 26A at predetermined sampling intervals.<sub>1</sub>, 26B<sub>1</sub>Reticle X Interferometer 16x and X Linear Encoder 26C<sub>1</sub>The measured values of are captured and stored in a memory (not shown), and the Y linear encoder 26A<sub>1</sub>And 26B<sub>1</sub>Measurement value and reticle Y interferometer 16y measurement value, reticle X interferometer 16x measurement value and X linear encoder 26C<sub>1</sub>For each of the measured values of, create a map as shown in Fig. 15. Here, three encoders 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>These three encoders 26A capture the measured values of the reticle R1 and R2 (pattern area) as long as the illumination area IAR passes through them.<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>This is because it is considered that the position of the reticle stage RST is controlled by using.
0129FIG. 15 is a diagram showing the relationship between the two when the horizontal axis is the measured value of the interferometer and the vertical axis is the measured value of the encoder, and the difference between this curve C and the ideal line TL is the encoder. Indicates the error included in the measured value. The diagram of FIG. 15 can be used as it is as a correction map for correcting the measured value of the encoder. The reason is that, for example, the point P1 in FIG. 15 indicates that the measured value of the corresponding interferometer is i1 when the measured value of the encoder is e1, but the measured value of this interferometer is at the extremely low speed described above. Since it is obtained when scanning the reticle stage RST, it can be considered that the error is an accurate value that can be ignored because it contains almost no short-term fluctuation error due to air fluctuation as well as long-term fluctuation error. Because.
0130Encoder 26A according to the correction map in Figure 15.<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>Encoder 26A corrected for the measured value of<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>The relationship between the corrected measured value of and the measured value of the corresponding interferometer is found to match the ideal line TL in FIG. Encoder 26C<sub>1</sub>The correction map that corrects the measured value of is driving the reticle stage RST in the movable range in the X-axis direction, and the encoder 26C obtained during the driving.<sub>1</sub>Of course, it may be created based on the measured value of the reticle X interferometer 16x.
0131The main controller 20 also includes the encoder 26A described above for the remaining encoders.<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>A correction map may be created using the measured values of the interferometers 16x and 16y in the same procedure as above.
0132However, when the short-term calibration operation described later is also executed in addition to the above-mentioned long-term calibration operation, the curve C of the above-mentioned correction map is divided into the low-order components of the offset component and the inclination component and other components. Separate it into higher-order components and have each of the lower-order component and higher-order component as a correction map, or separate the lower-order component into an offset component and a slope component and use each correction map as a higher-order component. You can bring it with you. Alternatively, have a correction map (correction information) for higher-order components that are not expected to fluctuate over a relatively long period of time, and perform short-term calibration of correction information for lower-order components that are expected to fluctuate in a relatively short period of time. It may be acquired by the operation.
0133In the above description, at least encoder 26A<sub>1</sub>, 26B<sub>1</sub>In the calibration operation for acquiring (determining) the correction information of the measured value of, the reticle stage RST is set in the scanning direction (Y-axis direction) over the range in which the pattern areas of the reticle R1 and R2 cross the illumination area IAR, respectively, as described above. Although it is assumed that it will move, the range of movement of the reticle stage RST is not limited to this. For example, encoder 26A<sub>1</sub>, 26B<sub>1</sub>It may be almost the entire measurable range (corresponding to the formation range of the diffraction grating of the moving scales 24A and 24B), or the moving range at the time of scanning exposure using either one of the reticle R1 and R2. The moving range during the scanning exposure may be the moving range of the reticle stage RST including at least a part of the acceleration / deceleration period and the synchronous settling period before and after the scanning exposure period as well as the scanning exposure period. The movement range of the reticle stage RST is not only the movement range of the reticle stage RST during scanning exposure using the reticle R1 and R2, but also the movement range during the measurement operation using the reference mark (not shown) provided in the reticle stage RST. May also be included. At least one of these reference marks is provided on the reticle stage RST on the -Y side with respect to the reticle R1 and / or on the + Y side with respect to the reticle R2.
0134Next, for example, the encoder 26A is performed for each wafer (so-called overhead time (between the end of exposure of the previous wafer and the start of exposure of the next wafer)).<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>The second calibration operation for calibrating the gain error (scaling error of the encoder measurement value with respect to the interferometer measurement value) will be described. Since this second calibration operation is performed for each wafer, that is, at relatively short intervals, it is also referred to as a short-term calibration operation below.
0135First, in the main control device 20, as shown in FIG. 16, the end on the -Y side of the pattern region of the reticle R1 (or R2) used for the next exposure in the scanning direction (Y-axis direction) is the illumination region. Position the reticle stage RST at the first Y position (hereinafter simply referred to as the first position) that coincides with the + Y end of the IAR. Even in this calibration operation, the illumination area IAR is not actually illuminated by the illumination light IL, but in FIG. 16, the illumination area IAR is illustrated in order to make it easy to understand the position of the reticle stage RST. ..
0136Then, the main control device 20 continues the positioning state of the reticle stage RST at the first position shown in FIG. 16 for a predetermined time, and the encoder 26A is maintained during the continuation of the positioning state.<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>, And the measured values of the interferometers 16x and 16y are acquired at predetermined sampling intervals and stored in a memory (not shown).
0137Next, the main controller 20 drives the reticle stage RST in the -Y direction, and as shown in FIG. 17, the end on the + Y side of the pattern region of the reticle R1 (or R2) is the illumination region IAR. -Position the reticle stage RST to the second Y position (hereinafter simply referred to as the second position) that coincides with the end on the Y side. Then, the main control device 20 continues the positioning state of the reticle stage RST at the second position shown in FIG. 17 for a predetermined time, and the encoder 26A is maintained during the continuation of the positioning state.<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>, And the measured values of the interferometers 16x and 16y are acquired at predetermined sampling intervals and stored in a memory (not shown).
0138Then, the main control device 20 uses the encoder 26A based on the measured values (information) stored in the memory at the first and second positions, respectively.<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>, And for each of the interferometers 16x and 16y, the added average value (time average value) of the measured values at the first and second positions is calculated. Then, based on this calculation result, the Y linear encoder 26A<sub>1</sub>And 26B<sub>1</sub>Measurement value and reticle Y interferometer 16y measurement value, and reticle X interferometer 16x measurement value and X linear encoder 26C<sub>1</sub>For each of the measured values of, create a map as shown in Fig. 18. In the map of FIG. 18, points P2 and P3 correspond to the measured values of the interferometer in which short-term fluctuations due to air fluctuations and the like at the first and second positions are reduced by the averaging effect. This is a point showing the relationship with the measured value of the encoder.
0139Next, the main controller 20 corrects the measured value of the encoder using the measured value of the interferometer. The slope component (scaling) S of the correction map.<sub>c</sub>Is calculated by the following formula. S<sub>c</sub>= (e3-e2) / (i3-i2) Then, the main control device 20 replaces the calculated inclination component of the correction map with the inclination component in the correction map of the low-order component, and has the correction map of the low-order component after the replacement and the high of the correction map. A new correction map for correcting the low-order component and the high-order component is created based on the next component.
0140In the above description, the reticle stage RST is set at two positions, the first position and the second position, which are the positions at both ends of the range in which the illumination area IAR passes through the pattern area of the reticle R1 (or R2) to be exposed. Positioning was performed and a predetermined process was performed to calculate the above-mentioned new correction information. However, not limited to this, in addition to the first position and the second position, the reticle stage RST is positioned at three or more positions including at least one position between these positions, and the same as above is performed. The processing may be performed to obtain the least squares approximate straight line of the obtained three or more points, and the offset component may be calculated in addition to the inclination component (scaling error) of the correction map based on the approximate straight line. In this case, a new correction for correcting the low-order component and the high-order component based on the calculated low-order component (inclination component and offset component) of the correction map and the high-order component held as the correction map. Just create a map. In addition, the first and second positions for positioning the reticle stage RST correspond to both ends of the movement range of the reticle stage RST for the entire pattern area of the reticle to cross the illumination area IAR with respect to the scanning direction. It corresponds to the range in which the reticle stage RST is actually moved during scanning exposure using either Reticle R1 or R2 (moving range including acceleration / deceleration period before and after scanning exposure and synchronous settling period). It may be a thing. Further, the range of movement in the scanning direction defined by the first and second positions may deviate at least in part from the range of movement of the reticle stage RST for the entire pattern area of the reticle to cross the illumination area IAR. , At least the range of movement thereof is preferably included. Further, the moving range of the reticle stage RST may include the moving range during the measurement operation using the reference mark described above.
0141Next, the encoder 26A is performed for each wafer (so-called overhead time).<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>The gain error (scaling error and offset of the encoder measurement value with respect to the interferometer measurement value), that is , the third calibration operation for updating the low-order component of the correction map described above will be described. For the same reason as described above, this third calibration operation is also referred to as a short-term calibration operation below.
0142First, the main controller 20 uses the reticle R1 for the next exposure at a low speed enough to maintain the throughput within the allowable range even if the throughput of the exposure device 100 decreases due to the execution of the third calibration operation. Drive the reticle stage RST in the Y-axis direction within a predetermined range through which the illumination region IAR passes through the pattern region (or R2). And while driving it, the interferometer 16x, 16y and the encoder 26A<sub>1</sub>, 26B<sub>1</sub>And 26C<sub>1</sub>The position information of the reticle stage RST is acquired at a predetermined sampling interval and stored in a memory (not shown). Even in this third calibration operation, the illumination area IAR is not illuminated by the illumination light IL, but for the same reason as described above, expressions such as "the illumination area IAR passes through" are used. .. Further, the moving range of the reticle stage RST is the same as the range described in the second calibration operation described above. However, in this third calibration operation, it is not necessary to position the reticle stage RST at both ends of the moving range.
0143Next, the main controller 20 is the Y linear encoder 26A as described above.<sub>1</sub>And 26B<sub>1</sub>Measurement value and reticle Y interferometer 16y measurement value, reticle X interferometer 16x measurement value and X linear encoder 26C<sub>1</sub>For the measured values of, create a curve like the curve C1 shown in FIG. In FIG. 19, reference numeral EA indicates a predetermined range in which the illumination region IAR passes through the pattern region of the reticle R1 (or R2), that is, an exposure section.
0144Next, the main controller 20 obtains the least squares approximate straight line FL of the curve C1 and obtains the offset drift OD and the scaling drift SD with respect to the ideal straight line TL of the approximate straight line FL. Then, using the obtained offset drift (offset error) and scaling drift (inclination error), the correction map of the low-order component that was previously held as a map is updated. Then, a new correction map for correcting the low-order component and the high-order component is created based on the correction map of the low-order component after this correction and the correction map of the high-order component that is held in advance as a map. ..
0145The movement range of the reticle stage RST in the third calibration operation may be at least partially deviated from the predetermined range (corresponding to the exposure section EA) for the entire pattern area of the reticle to cross the illumination area IAR. However, it is preferable to include at least the predetermined range, for example, the range in which the reticle stage RST is actually moved during scanning exposure using either Reticle R1 or R2 (acceleration / deceleration period before and after scanning exposure and synchronous settling period). (Movement range including) may be used. Further, the moving range of the reticle stage RST may include the moving range during the measurement operation using the reference mark described above.
0146In the exposure apparatus 100, the long-term calibration operation and the short-term calibration operation of the encoders 50A to 50D used for position control of the wafer stage WST during the exposure operation are performed by the main controller 20 in the first to third described above. It is performed in the same manner as the calibration operation. However, the movement of the wafer stage WST is performed in a two-dimensional plane. In this case, the wafer Y interferometer 18Y and the wafer X interferometer 18X<sub>1</sub>A correction map based on the error distribution of the measured values of the X linear encoders 50B and 50D by driving the wafer stage WST on the Cartesian coordinate system defined by, and the error distribution of the measured values of the Y linear encoders 50A and 50C. A correction map based on is required. At this time, the Y linear encoders 50A and 50C have the Y-axis direction in both the arrangement direction and the longitudinal direction of the diffraction gratings of the moving scales 44A and 44C, and the longitudinal direction (head arrangement direction) of the head units 46A and 46C is X. Axial.
0147Next, the long-term calibration operation (first calibration operation) of the encoders 50A to 50D performed by the exposure apparatus 100 of the present embodiment, that is, the correction information of the lattice pitch of the moving scale of the wafer stage WST and the correction information of the lattice deformation. The acquisition operation of the above will be described with reference to FIG.
0148In FIG. 20, the measurement beam B4 from the Y interferometer 18Y<sub>1</sub>, B4<sub>2</sub>Are symmetrically arranged with respect to a straight line parallel to the Y axis (corresponding to the straight line connecting the centers of the heads of the head unit 46B and the head unit 46D) passing through the optical axis of the projection optical system PL, and of the Y interferometer 18Y. The actual length measurement axis coincides with a straight line parallel to the Y axis that passes through the optical axis of the projection optical system PL. Therefore, according to the Y interferometer 18Y, the Y position of the wafer stage WST can be measured without an abbe error. Similarly, the X interferometer 18X<sub>1</sub>The measurement beam from is placed on a straight line parallel to the X axis (corresponding to the straight line connecting the centers of the heads of the head unit 46A and the head unit 46C) passing through the optical axis of the projection optical system PL, and X interferometry. 18X in total<sub>1</sub>The axis of length measurement coincides with a straight line parallel to the X axis that passes through the optical axis of the projection optical system PL. Therefore, the X interferometer 18X<sub>1</sub>According to this, the X position of the wafer stage WST can be measured without an abbe error during exposure or the like.
0149Here, as an example, the acquisition operation of the correction information of the deformation (bending of the grid line) of the X-scale grid line and the correction information of the Y-scale grid pitch will be described. Here, for the sake of simplicity, it is assumed that the reflecting surface of the moving mirror 17X is an ideal plane.
0150First, the main controller 20 is a Y interferometer 18Y, an X interferometer 18X.<sub>1</sub>And Z interferometer 18Z<sub>1</sub>, 18Z<sub>2</sub>The wafer stage WST is driven based on the measured values of, and as shown in FIG. 20, the moving scales 44A and 44C are arranged directly under the corresponding head units 46A and 46C (at least one head), and the moving scales are arranged. (Diffraction grating) Position the wafer stage WST at a position where one end on the + Y side of 44A and 44C coincides with the corresponding head units 46A and 46C, respectively.
0151Next, the main controller 20 has a low speed at which short-term fluctuations of the measured values of the Y interferometer 18Y can be ignored, and the X interferometer 18X.<sub>1</sub>Y interferometer 18Y and Z interferometer 18Z while fixing the measured value of<sub>1</sub>, 18Z<sub>2</sub>As shown by the arrow F in FIG. 20, for example, the other end (one end on the -Y side) of the moving scales 44A and 44C, while maintaining the pitching amount, rolling amount, and yawing amount at zero based on the measured values of. ) Matches the corresponding head units 46A and 46C, respectively, and moves the wafer stage WST in the + Y direction. During this movement, the main controller 20 uses the measured values of the Y linear encoders 50A and 50C and the measured values of the Y interferometer 18Y (measurement beam B4).<sub>1</sub>, B4<sub>2</sub>The relationship between the measured values of the Y linear encoders 50A and 50C and the measured values of the Y interferometer 18Y is obtained based on the captured measured values. That is, the main control device 20 has a grid pitch (interval between adjacent grid lines) of the moving scales 44A and 44C which are sequentially arranged to face the head units 46A and 46C as the wafer stage WST moves, and the grid pitch of the grid pitch. Ask for correction information. The correction information of the grid pitch can be obtained, for example, as a correction map showing the relationship between the two when the horizontal axis is the measured value of the interferometer and the vertical axis is the measured value of the encoder. Since the measured value of the Y interferometer 18Y in this case is obtained when the wafer stage WST is scanned at the extremely low speed described above, it is not only a long-term fluctuation error but also a short-term fluctuation due to air fluctuations and the like. Almost no error is included, and the error can be considered as an accurate value that can be ignored. Here, it is assumed that the wafer stage WST is driven in the Y-axis direction over a range in which both ends of the moving scales 44A and 44C cross the corresponding head units 46A and 46C. The wafer stage WST may be driven within the range in the Y-axis direction in which the wafer stage WST is moved.
0152Further, the main control device 20 is a measured value (X) obtained from a plurality of heads of the head units 46B and 46D which are sequentially arranged to face the moving scales 44B and 44D as the wafer stage WST moves. By statistically processing (measured values of linear encoders 50B and 50D), for example, averaging (or weighting averaging), correction information for deformation (bending) of grid lines sequentially facing the plurality of heads is also obtained. .. This is because if the reflecting surface of the moving mirror 17X is an ideal plane, the same blur pattern should appear repeatedly in the process of feeding the wafer stage WST in the + Y direction, so multiple heads should be used. This is because by averaging the acquired measurement data, it is possible to accurately obtain correction information for deformation (bending) of the grid lines of the moving scales 44B and 44D that sequentially face the plurality of heads.
0153If the reflecting surface of the moving mirror 17X is not an ideal flat surface, the unevenness (bending) of the reflecting surface is measured in advance to obtain the correction data for the bending. Then, when the above-mentioned wafer stage WST moves in the + Y direction, the X interferometer 18X<sub>1</sub>Instead of fixing the measured value of the above to a predetermined value, the wafer stage WST may be moved accurately in the Y-axis direction by controlling the X position of the wafer stage WST based on the correction data. By doing so, it is possible to obtain the correction information of the grid pitch of the moving scales 44A and 44C and the correction information of the deformation (bending) of the grid lines of the moving scales 44B and 44D in exactly the same manner as described above. The measurement data acquired by the plurality of heads of the head units 46B and 46D are a plurality of data based on different parts of the reflecting surface of the moving mirror 17X, and all the heads have the same lattice line deformation (bending). Since the measurement is performed, the bending correction residual of the reflecting surface is averaged by the above averaging and approaches the true value (in other words, the measurement data acquired by a plurality of heads (bending of the grid line). By averaging the information), the influence of the bending residual can be diminished).
0154The X linear encoders 50B and 50D have the Y linear encoders 50A and 50C in the arrangement direction and the longitudinal direction of the diffraction grids of the moving scales 44B and 44D and the longitudinal direction (head arrangement direction) of the head units 46B and 46D. Since the X-axis and Y-axis directions are only opposite, the operation of acquiring the correction information for the deformation (bending of the grid lines) of the Y-scale grid lines and the correction information for the grid pitches of the moving scales 50B and 50D (first calibration). In the case of the operation), the above-mentioned correction and the processing in which the X-axis direction and the Y-axis direction are exchanged may be performed, so detailed description thereof will be omitted.
0155In this way, the main controller 20 provides correction information for the grid pitch of the moving scales 44A and 44C and correction information for deformation (bending) of the grid lines of the moving scales 44B and 44D at predetermined timings, for example, for each lot. , And the correction information of the grid pitch of the moving scales 44B and 44D and the correction information of the deformation (bending) of the grid lines of the moving scales 44A and 44C are obtained.
0156Then, during the exposure processing of the wafers in the lot, the main controller 20 transfers the measured values obtained from the head units 46A and 46C (that is, the measured values of the encoders 50A and 50C) to the grids of the moving scales 44A and 44C. The position of the wafer stage WST in the Y-axis direction is controlled while correcting based on the pitch correction information and the grid line deformation (bending) correction information. As a result, the position control of the wafer stage WST in the Y-axis direction can be performed accurately using the linear encoders 50A and 50C without being affected by changes in the grid pitch of the moving scales 44A and 44C over time and bending of the grid lines. It becomes possible to do.
0157Further, during the exposure processing of the wafers in the lot, the main controller 20 transfers the measured values obtained from the head units 46B and 46D (that is, the measured values of the encoders 50B and 50D) to the grids of the moving scales 44B and 44D. The position of the wafer stage WST in the X-axis direction is controlled while correcting based on the pitch correction information and the grid line deformation (bending) correction information. As a result, the linear encoders 50B and 50D are used to accurately control the position of the wafer stage WST in the X-axis direction without being affected by changes in the grid pitch of the moving scales 44B and 44D over time and bending of the grid lines. It becomes possible to do.
0158In the above description, it is assumed that the grid pitch and the grid line bending correction information are acquired for all of the moving scales 44A to 44D, but the moving scales 44A and 44C and the moving scales 44B are not limited to this. The correction information of the grid pitch and the grid line bending may be acquired only for any of the grid pitch and the grid line bending, and for both the moving scales 44A and 44C and the moving scales 44B and 44D, either the grid pitch or the grid line bending may be acquired. You may get only the correction information about.
0159Although detailed description is omitted, the short-term calibration operation (second and third calibration operations) of the encoders 50A to 50D used for position control of the wafer stage WST during the exposure operation is also the above-mentioned long-term calibration operation. It is performed according to (first calibration operation).
0160Then, during the step-and-scan exposure operation, the encoder 26A is operated by the main controller 20 as described above.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>The position of the reticle stage RST is controlled based on the measured value of the reticle stage RST and the correction map thereof, and the position of the wafer stage WST is controlled based on the measured value of the encoders 50A to 50D and the correction map thereof.
0161Further, in the exposure apparatus 100 of the present embodiment, the reticle R1 and the reticle R2 can be placed on the reticle stage RST at the same time. Therefore, the main controller 20 performs the reticle alignment on the reticle R1 and the reticle R2, so that the encoder 26A does not perform the reticle exchange operation with respect to the reticle stage RST.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>By simply moving the reticle stage RST based on the measured value of, for example, double exposure can be performed using the reticle R1 and the reticle R2.
0162The encoders used in the present embodiment are not limited to the diffraction interference method described above, and various types such as a so-called pickup method can be used, and are disclosed in, for example, US Pat. No. 6,639,686. A so-called scan encoder or the like can be used.
0163As described in detail above, according to the exposure apparatus 100 according to the present embodiment, the main control apparatus 20 causes, for example, the encoder 26A.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Calibration operations such as are performed. That is, encoder 26A<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Encoder 26A, which has excellent short-term stability of measured values compared to the interferometers 16y and 16x, using the measured values of interferometers 16y and 16x, which are superior in linearity and long-term stability of measured values.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>Correction information for correcting measured values such as is acquired. Then, the main control device 20 uses the encoder 26A at the time of scanning exposure or the like.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>The reticle stage RST is driven based on the measured value of the above and the correction information.
0164Therefore, the encoder 26A corrected using the correction information.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>The reticle stage RST can be driven accurately based on the measured value of the reticle stage RST, that is, the position information of the reticle stage RST having good linearity and long-term stability as well as short-term stability.
0165Further, according to the exposure apparatus 100 of the present embodiment, the encoder 26A is obtained by the long-term calibration described above.<sub>1</sub>, 26B<sub>1</sub>Encoder 26A, which is superior in short-term stability of measured values compared to the interferometer 16y, using the measured values of the interferometer 16y, which is superior in linearity and long-term stability of measured values.<sub>1</sub>, 26B<sub>1</sub>Correction information for correcting the measured value of is acquired. Then, the main controller 20 uses the encoder 26A at the time of pattern transfer or the like.<sub>1</sub>, 26B<sub>1</sub>The movement of the reticle stage RST is controlled based on the measured value of the above and the correction information. Therefore, the encoder 26A corrected using the correction information.<sub>1</sub>, 26B<sub>1</sub>It is possible to accurately control the movement of the reticle stage RST in the scanning direction based on the measured value of the reticle stage RST, that is, the position information in the scanning direction of the reticle stage RST, which has good linearity and long-term stability as well as short-term stability. ..
0166Further, according to the exposure apparatus 100 of the present embodiment, the encoder 26A is obtained by any of the short-term calibrations described above.<sub>1</sub>, 26B<sub>1</sub>Interferometer 16y, which is superior in linearity and long-term stability of measured values, and encoder 26A, which is superior in short-term stability of measured values compared to the interferometer 16y.<sub>1</sub>, 26B<sub>1</sub>Correction information for correcting low-order components (scaling error, or scaling error and scaling offset) of the map information indicating the relationship with the measured value of is acquired. Then, the main controller 20 uses the encoder 26A at the time of pattern transfer or the like.<sub>1</sub>, 26B<sub>1</sub>The movement of the reticle stage RST is controlled based on the measured value of the above and the map information in which the low-order component is corrected by using the above correction information.
0167Further, according to the exposure apparatus 100, the calibration operation of the encoders 50A to 50D, for example, is performed by the main controller 20 by the above-mentioned encoder 26A.<sub>1</sub>, 26B<sub>1</sub>It is performed in the same manner as the calibration operation of. That is, the interferometers 18Y, 18X<sub>1</sub>Interferometers 18Y, 18X, which have better short-term stability of measured values than encoders 50A to 50D, and better linearity and long-term stability of measured values than encoders 50A to 50D.<sub>1</sub>Correction information to be corrected using the measured value of is acquired. Then, the main control device 20 drives the wafer stage WST based on the measured values of the encoders 50A to 50D and the correction information at the time of scanning exposure, step movement between shot regions, and the like.
0168Therefore, based on the measured values of the encoders 50A to 50D corrected using the correction information, that is, the position information in the X-axis and Y-axis directions of the wafer stage WST having good linearity and long-term stability as well as short-term stability. The wafer stage WST can be driven accurately in either the X-axis or Y-axis direction.
0169Therefore, in the exposure apparatus 100 of the present embodiment, the main control apparatus 20 uses the encoder 26A during scanning exposure to each shot region on the wafer.<sub>1</sub>, 26B<sub>1</sub>, 26C<sub>1</sub>, And the reticle R1 or R2 (reticle stage RST) and wafer W (wafer stage WST) can be driven accurately along the scanning direction (Y-axis direction) based on the measured values of the encoders 50A to 50D). At the same time, highly accurate positioning (alignment) between the reticle R1 or R2 (reticle stage RST) and the wafer W (wafer stage WST) in the non-scanning direction (X-axis direction) is also possible. This makes it possible to accurately form a pattern of the reticle R1 (or R2) in a plurality of shot regions on the wafer W.
0170In the exposure device 100 of the present embodiment, the main control device 20 updates the correction information of the measured values of the encoder based on the measured values of the encoder and the interferometer obtained by moving the reticle stage RST separately from the exposure operation. However, for example, the correction information may be updated using the measured values of the encoder and the interferometer obtained while the reticle stage RST is moving during the exposure operation. That is, when performing a step-and-scan exposure operation in which the pattern of the reticle R1 (or R2) is sequentially transferred to a plurality of shot regions on the wafer W, for example, during the scan exposure of each shot region, the reticle stage RST The position is controlled based on the measured value of the encoder and its correction information, and in parallel with the control (exposure operation of the wafer), the measured values of the interferometer and the encoder are accumulated, and based on the accumulated measured values, the position is accumulated. Sequential calibration of the encoder measurement error to calibrate the correction information (eg, the map information shown in FIG. 21 showing the relationship between the interferometer and encoder measurements) prior to the next wafer exposure. You may do it.
0171In FIG. 21, the symbol C2 indicates the average value of the accumulated data, and the data of this average value is averaged with short-term fluctuations of the measured values of the interferometer (fluctuations of the measured values due to air fluctuations, etc.). There is. In this case, it is not necessary to accumulate the data during the scanning exposure for all the shot regions, and it is sufficient to accumulate the data during the scanning exposure for a number of shot regions sufficient to average the short-term fluctuations of the measured values of the interferometer. .. In FIG. 21, reference numeral EA indicates an exposure section similar to that in FIG.
0172Even in this case, when the next wafer is exposed by the step-and-scan method, the movement of the reticle stage RST during the scan exposure (during pattern transfer) of each shot area is corrected by the correction information (for example, the map information in FIG. 21). It is possible to accurately control the measured value of the encoder corrected by using the position information of the reticle stage, which has good linearity and long-term stability as well as short-term stability. This makes it possible to accurately transfer the pattern formed on the reticle R1 (or R2) to a plurality of shot regions on the wafer by scanning exposure. This calibration may be performed not only on the Y linear encoder but also on the X linear encoder, and further, it may be performed on the wafer stage encoder system (encoder 50A to 50D).
0173In the exposure apparatus 100 of the above embodiment, the correction information of the grid pitch of the moving scale and the correction information of the bending of the grid lines may be acquired by the method according to the modification described below.
0174Here, the operation of acquiring the correction information of the grid pitch of the moving scales 44A and 44C and the operation of acquiring the correction information of the deformation (bending of the grid line) of the grid lines of the moving scales 44B and 44D will be described. Further, for the sake of simplicity, the reflecting surface of the moving mirror 17X is assumed to be an ideal plane.
0175First, the main controller 20 is an X interferometer 18X.<sub>1</sub>Y interferometer 18Y and Z interferometer 18Z while fixing the measured value of<sub>1</sub>, 18Z<sub>2</sub>The wafer stage WST is moved in the + Y direction indicated by the arrow F in FIG. 22 in the stroke range described above, for example, while maintaining the pitching amount, rolling amount, and yawing amount to zero based on the measured values of. During this movement, the main controller 20 uses the measured values of the encoders 50A and 50C and the measured values of the Y interferometer 18Y (measurement beam B4).<sub>1</sub>, B4<sub>2</sub>(Measured value by) is taken into the internal memory at a predetermined sampling interval. In this case, the measured value of the encoder 50C is circled in FIG. 22 at a distance a in the + X direction from the straight line LV parallel to the Y axis passing through the optical axis of the projection optical system PL facing the moving scale 44C. Obtained from the head 48k of the head unit 46C shown enclosed. The measured value of the encoder 50A is obtained from the head 48e of the head unit 46A circled in FIG. 22 at a distance b in the -X direction from the straight line LV facing the moving scale 44A.
0176Next, the main controller 20 is an X interferometer 18X.<sub>1</sub>After moving the wafer stage WST by a predetermined distance in the + X direction based on the measured value of, the wafer stage WST was moved by a predetermined distance in the -Y direction indicated by the arrow F'in FIG. 22 based on the measured value of the Y interferometer 18Y. Stop at the position.
0177Then, the main controller 20 is an X interferometer 18X.<sub>1</sub>Y interferometer 18Y and Z interferometer 18Z while fixing the measured value of<sub>1</sub>, 18Z<sub>2</sub>While maintaining the pitching amount and rolling amount to zero and the yawing amount to zero as much as possible based on the measured values of, for example, the wafer stage WST is moved in the + Y direction indicated by the arrow F in FIG. 23 in the above stroke range. Let me. During this movement, the main controller 20 uses the measured values of the encoders 50A and 50C and the measured values of the Y interferometer 18Y (measurement beam B4).<sub>1</sub>, B4<sub>2</sub>(Measured value by) is taken into the internal memory at a predetermined sampling interval. In this case, the measured value of the encoder 50C is obtained from the head 48e of the head unit 46C, which is circled in FIG. 23 and is located at a distance b in the + X direction from the straight line LV, which faces the moving scale 44C. The measured value of the encoder 50A is obtained from the head 48k of the head unit 46A, which is circled in FIG. 23 and is located at a distance a in the -X direction from the straight line LV, which faces the moving scale 44A.
0178However, since the positions of each head on the XY coordinate system are known, simultaneous equations are established using the sampling values obtained in the above two operations, and by solving these simultaneous equations, the moving scales 44C and 44A The correction information (for example, the correction map) of the grid pitch of the above can be obtained independently.
0179If the reflecting surface of the moving mirror 17X is not an ideal flat surface, the unevenness (bending) of the reflecting surface is measured in advance to obtain the correction data for the bending. Then, when the wafer stage WST shown in FIGS. 22 and 23 is moved in the + Y direction, the X interferometer 18X<sub>1</sub>Instead of fixing the measured value of the above to a predetermined value, the wafer stage WST may be moved accurately in the Y-axis direction by controlling the X position of the wafer stage WST based on the correction data.
0180After obtaining the correction information (for example, correction map) of the lattice pitches of the moving scales 44A and 44C as described above, the main controller 20 sets the wafer stage WST as described above, for example, as shown in FIG. Move in the + Y direction in the same procedure as in Fig. 22 and so on. In this case, unlike the case of acquiring the correction information of the grid pitches of the moving scales 44A and 44C, the head 48g of the head unit 46B circled in FIG. 24 facing the moving scales 44B and 44D, respectively. And the head 48i of the head unit 46D is the X interferometer 18X<sub>1</sub>It is off the length measurement axis of. Therefore, the influence of the apparent yawing amount of the wafer stage WST measured by the interferometer due to air fluctuation is regarded as an error (hereinafter, abbreviated as the yawing-induced error) of the encoders 50B and 50D (head unit 46B). It is included in the measured values of the head 48g and the head 48i) of the head unit 46D. However, in this case, the encoders 50A and 50C (the head 48h of the head unit 46A and the head 48h of the head unit 46C shown in a circle in FIG. 24, which face the moving scales 44A and 44C, respectively) are used as described above. The apparent yawing amount of the wafer stage WST measured by an interferometer due to air fluctuations can be measured. That is, the main controller 20 corrects the measured values of the encoders 50A and 50C by using the previously obtained correction information of the grid pitches of the moving scales 44C and 44A, and describes the above based on the corrected measured values. The apparent yawing amount of the wafer stage WST can be obtained. Then, the main controller 20 can correct the above-mentioned yawing-induced error by using the obtained apparent yawing amount.
0181While the main controller 20 is moving the wafer stage WST in the + Y direction, the head units 46B and 46D are sequentially arranged to face the moving scales 44B and 44D while correcting the yawing-induced error as described above. The measured values obtained from the plurality of heads of the above are taken into the internal memory at predetermined sampling intervals. Then, for the same reason as described above, the main controller 20 statistically processes the measured values taken into the internal memory, for example, averaging (or weighting averaging), thereby deforming the grid lines of the moving scales 44B and 44D. Also ask for correction information for (bending).
0182Further, in consideration of the so-called forward / reverse difference, the wafer stage WST is driven in the -Y direction indicated by the arrow F'in FIGS. 22, 23 and 24 to correct the lattice pitch of the moving scales 44A and 44C ( For example, when obtaining correction information for deformation (bending) of the grid lines of the correction map) and / or the moving scales 44B and 44D, the same processing as described above may be performed.
0183On the other hand, when acquiring the correction information of the deformation (bending) of the grid lines of the moving scales 44A and 44C and the correction information of the grid pitch of the moving scales 44B and 44D, the main controller 20 uses the above case and the X-axis. The processing is performed by exchanging the direction and the Y-axis direction, but the detailed description thereof will be omitted.
0184Since each scale (diffraction grating) has a width, the above-mentioned lattice pitch correction information is acquired in the width direction, for example, along the three lines in the center of the left and right, and a typical lattice for lattice bending is obtained. It suffices to pick up the line and measure the bend. This is preferable from the viewpoint of accuracy and workability.
0185According to the method according to the deformation example described above, when acquiring the correction information of the grid pitch of the scale and / or the correction information of the deformation (bending of the grid line) of the grid line of the scale, the wafer stage WST is not necessarily performed at an extremely low speed. Since it is not necessary to move the correction information, it is possible to acquire the correction information in a short time.
0186Next, a modification of the encoder system for the wafer stage will be described with reference to FIGS. 25 and 26. Since the difference between FIGS. 25 and 26 is only the configuration of the encoder system, the same reference numerals are given to the components having the same or equivalent operations and functions as those in FIG. 3, and the description thereof is omitted below. To do.
0187As shown in FIG. 25, two moving scales 52A and 52B, which are orthogonal to each other in the longitudinal direction and have the longitudinal direction in the Y-axis direction and the X-axis direction, respectively, are fixed in an L shape on the upper surface of the wafer stage WST. ing. The two moving scales 52A and 52B have a reflection type diffraction grating whose periodic direction is orthogonal to the longitudinal direction on the surface thereof.
0188In addition, the head unit 46A and the pair of head units 46B<sub>1</sub>, 46B<sub>2</sub>Is arranged so as to intersect with the corresponding moving scales 52A and 52B, respectively, and is fixed to the lens barrel surface plate 38 in a suspended state via a support member (not shown). The head unit 46A passes through the optical axis AX of the projection optical system PL with the X-axis direction (periodic direction of the diffraction lattice) orthogonal to the longitudinal direction (Y-axis direction) of the moving scale 52A as the longitudinal direction (head arrangement direction). It is arranged on an axis (central axis) parallel to the X axis, and together with the moving scale 52A, constitutes an X linear encoder 56A that measures the position information of the wafer stage WST in the X axis direction. Pair of head units 46B<sub>1</sub>, 46B<sub>2</sub>The Y-axis direction (periodic direction of the diffraction lattice) orthogonal to the longitudinal direction (X-axis direction) of the moving scale 52B is set as the longitudinal direction (head arrangement direction), and the Y-axis passes through the optical axis AX of the projection optical system PL. It is arranged symmetrically with respect to the parallel axis (central axis), and together with the moving scale 52B, constitutes a Y linear encoder 56B that measures two position information in the Y-axis direction of the wafer stage WST.
0189Further, the measured values of the two linear encoders 56A and 56B are supplied to the main controller 20, and the main controller 20 is based on the position information in the X-axis and Y-axis directions and the rotation information in the θz direction, and the wafer stage drive system 27 The position of the wafer stage WST is controlled via. As a result, it is possible to drive the wafer stage WST in two dimensions with high accuracy in exactly the same manner as in the above embodiment.
0190FIG. 26 is a diagram showing another modification of the encoder system for the wafer stage, and the difference from FIG. 25 is that apart from the above-mentioned set of linear encoders 56A and 56B, another set of linear encoders 56C and 56D It is only the point that provided. As shown in FIG. 26, two moving scales 52C and 52D, which are orthogonal to each other in the longitudinal direction and have the longitudinal direction in the Y-axis direction and the X-axis direction, respectively, are fixed in an L shape on the upper surface of the wafer stage WST. ing. The two moving scales 52C and 52D have a reflective diffraction grating whose periodic direction is orthogonal to the longitudinal direction on the surface thereof, and are arranged symmetrically with respect to the moving scales 52A and 52B with respect to the center of the wafer stage WST. ing.
0191In addition, the head unit 46C and the pair of head units 46D<sub>1</sub>, 46D<sub>2</sub>Is arranged so as to intersect with the corresponding moving scales 52C and 52D, respectively, and is fixed to the lens barrel surface plate 38 in a suspended state via a support member (not shown). The head unit 46C described above with respect to the optical axis AX of the projection optical system PL, with the X-axis direction (periodic direction of the diffraction lattice) orthogonal to the longitudinal direction (Y-axis direction) of the moving scale 52C as the longitudinal direction (head arrangement direction). (That is, on the axis parallel to the X axis (central axis) passing through the optical axis AX described above) and in the X-axis direction of the wafer stage WST together with the moving scale 52C. Configure the X linear encoder 56C to measure position information. Pair of head units 46D<sub>1</sub>, 46D<sub>2</sub>Each has the Y-axis direction (periodic direction of the diffraction grating) orthogonal to the longitudinal direction (X-axis direction) of the moving scale 52D as the longitudinal direction (head arrangement direction), and the above-mentioned head unit with respect to the optical axis AX of the projection optical system PL. 46B<sub>1</sub>, 46B<sub>2</sub>(That is, symmetrically arranged with respect to the axis parallel to the Y axis (central axis) passing through the optical axis AX described above), and two positions in the Y-axis direction of the wafer stage WST together with the moving scale 52D. A Y linear encoder 56D that measures information is configured.
0192Further, the measured values of the four linear encoders 56A to 56D are supplied to the main controller 20, and the main controller 20 is based on the position information in the X-axis and Y-axis directions and the rotation information in the θz direction, and the wafer stage drive system 27 The position of the wafer stage WST is controlled via. As a result, it is possible to drive the wafer stage WST in two dimensions with high accuracy in exactly the same manner as in the above embodiment. Since the encoder system of FIG. 26 has four linear encoders 56A to 56D, the wafer is exposed even if the head unit is not placed closer to the projection optical system PL than the encoder system of FIG. 25. Regardless of the position of the wafer stage WST during operation, the position information of the wafer stage WST (position information in the X-axis and Y-axis directions and rotation information in the θz direction) is always obtained from at least three of the four linear encoders 56A to 56D. Obtainable. Further, in the encoder system of FIG. 26, the Y linear encoders 56B and 56D each have two head units, but the present invention is not limited to this, and for example, it may have only one head unit.
0193Here, the above-mentioned wafer X interferometer 18X<sub>1</sub>Has at least one length measuring axis including a length measuring axis (corresponding to the solid line in the figure) that coincides with an axis (central axis) parallel to the X axis passing through the optical axis AX of the projection optical system PL. Then, in the encoder system shown in FIGS. 25 and 26, the measurement axis (head arrangement direction) of the head unit 46A (and 46C) of the X linear encoder 56A (and 56C) is the central axis (wafer X interferometer 18X).<sub>1</sub>It is arranged so as to coincide with the length measurement axis in the X measurement of. In addition, the wafer Y interferometer 18Y described above has two length measurement axes (Figs. 25 and 26) that are symmetrical with respect to the axis (central axis) parallel to the Y axis that passes through the optical axis AX of the projection optical system PL and the detection center of the alignment system ALG. Beam B4 shown by solid line inside<sub>1</sub>, B4<sub>2</sub>It has multiple length measurement axes including (corresponding to). And the Y linear encoder 56B (and 56D) is the head unit 46B.<sub>1</sub>, 46B<sub>2</sub>(And 46D<sub>1</sub>, 46D<sub>2</sub>) Measurement axes (head arrangement direction) are arranged so as to coincide with the two measurement axes. As a result, it becomes difficult for a difference in the measured values to occur between the linear encoder and the wafer interferometer whose measurement axis and length measurement axis coincide with each other, and the above-mentioned calibration operation can be performed with high accuracy. In this modification, the measurement axis of the linear encoder and the length measurement axis of the wafer interferometer are matched, but the present invention is not limited to this, and both axes may be offset in the XY plane. This also applies to the above embodiment (FIG. 3).
0194In the encoder system shown in FIGS. 25 and 26, the two or four moving scales (52A to 52D) are made of the same material (for example, ceramics or glass with low thermal expansion), and each of them is formed in the longitudinal direction. The length (corresponding to the width of the diffraction grating) covers at least the entire moving stroke (moving range) of the wafer stage WST during the exposure operation of the wafer W (in other words, each head during scanning exposure of all shot regions). It is set longer than the size (diameter) of the wafer W so that the unit (measurement beam) does not deviate from the corresponding moving scale (diffraction grating), that is, it does not become unmeasurable). Also, in the encoder system shown in FIGS. 25 and 26, 3 or 6 head units (46A to 46D).<sub>2</sub>) May have, for example, a single head or a plurality of heads arranged almost seamlessly, but in the encoder systems shown in FIGS. 25 and 26, they are all arranged at predetermined intervals along the longitudinal direction thereof. It is assumed that it has a plurality of heads. Furthermore, each head unit has the same range as the diffraction grating formation range in the direction orthogonal to the longitudinal direction of the moving scale (diffraction grating arrangement direction), that is, the interval at which two adjacent heads do not deviate from the corresponding moving scale (diffraction grating). A plurality of heads are arranged at intervals of less than or equal to a degree. Also, 3 or 6 head units (46A ~ 46D)<sub>2</sub>) Covers at least the entire moving stroke (moving range) of the wafer stage WST during the exposure operation of the wafer W in its length (corresponding to the detection range of the diffraction grating) in the longitudinal direction (in other words, all). The head unit (measurement beam) is set to be equal to or higher than the movement stroke so that the head unit (measurement beam) does not deviate from the corresponding movement scale (diffraction grating) during scanning exposure of the shot area of
0195Further, even in the exposure apparatus provided with the encoder system shown in FIGS. 25 and 26, the correction information of the measured value of each encoder is obtained in exactly the same manner as the exposure apparatus 100 (including the encoder system shown in FIG. 3) of the above embodiment. The calibration operation to be determined (the first to third calibration operations described above) is performed. In this case, as an example, in each encoder, the position of the moving scale is set so that one end of the moving scale coincides with the corresponding head unit in the longitudinal direction, and then the moving scale is moved in the arrangement direction of the diffraction grating (the direction orthogonal to the longitudinal direction). Move the scale at least as far as its width. Further, the moving scale is moved in its longitudinal direction by a distance comparable to the size of the measurement beam in one head of the head unit, and then similarly, the moving scale is approximately comparable in width with respect to the alignment direction of the grating. Move more than a distance. Hereinafter, the above operation is repeatedly executed until the other end of the moving scale coincides with the head unit. Then, the correction information of the encoder may be determined based on the measured value of the encoder obtained by this drive and the wafer interferometer having the same measurement direction as the encoder. Here, it is assumed that the wafer stage WST is driven over a range in which both ends of the moving scale coincide with the corresponding head unit in the longitudinal direction, but the present invention is not limited to this, and the wafer stage WST moves, for example, during the wafer exposure operation. The wafer stage WST may be driven within its longitudinal range.
0196By the way, in the above-described embodiment and modification, the positions of the reticle stage RST and the wafer stage WST are controlled by using only the above-mentioned encoder system (FIGS. 2, FIG. 3, FIG. 25, FIG. 26) during the wafer exposure operation. did. However, even if the above-mentioned (especially short-term) calibration operation is performed, for some reason (for example, foreign matter adheres to the moving scale, the moving scale is displaced, the head unit collapses or its telesen collapses, the allowable range Due to the displacement of the moving scale exceeding the above in the Z direction (direction orthogonal to the surface), there is a problem that the position measurement becomes impossible or the measurement accuracy exceeds the allowable range, and the above position control is performed during the exposure operation. At least a part of the necessary position information in the X-axis and Y-axis directions and rotation information in the θz direction may not be obtained. Since the encoder system shown in FIGS. 3 and 26 has four encoders, the position control cannot be performed even if the above problem occurs in one encoder, but the encoders shown in FIGS. 2 and 25 are not disabled. In the system, if the above problem occurs in one encoder, the position control cannot be performed.
0197Therefore, a first drive mode using the position information measured by the above-mentioned encoder system and a second drive mode using the position information measured by the above-mentioned interferometer system are prepared, and usually the first drive mode is set. Set to be used during the exposure operation. Then, when at least a part of the position information in the X-axis and Y-axis directions and the rotation information in the θz direction required for position control cannot be obtained, for example, during an exposure operation, the first drive mode is changed to the second drive mode. It is preferable to switch to control the position of the reticle stage or the wafer stage. Further, a third drive mode in which at least a part of the position information measured by the above-mentioned encoder system and at least a part of the position information measured by the above-mentioned interferometer system are used in combination is also prepared, and the first drive mode is prepared. It may be possible to control the position of the reticle stage or the wafer stage by using one of the second and third drive modes instead of the mode. The switching of the first drive mode to the second drive mode (or the third drive mode) is not limited to the exposure operation, and the switching is also performed in other operations (for example, measurement operation such as alignment). May be done. In addition, it is not necessary to set the first drive mode in advance for other operations, and even if another drive mode (for example, one of the second and third drive modes) is set instead of the first drive mode. good. In this case, when the position of the stage is controlled by another drive mode, for example, if an error occurs, the stage is switched to another drive mode (for example, the other of the second and third drive modes, or the first drive mode). Is also good. Further, any drive mode may be selectable except for the exposure operation.
0198In the above embodiment and the modified example, the interferometer 18X is used during the switching operation of the position measurement system.<sub>1</sub>After stopping the wafer stage WST for a predetermined time until the effect of short-term fluctuations due to air fluctuations (air temperature fluctuations) of 18Y measured values becomes negligible due to the averaging effect, the interferometer 18X<sub>1</sub>, The case where the measured value of 18Y is taken over by the encoders 50A to 50D has been described, but the present invention is not limited to this, and for example, the same operation as the second calibration operation described above is performed, and the interferometer is based on the obtained low-order component. 18X<sub>1</sub>, 18Y may take over the measured values from encoders 50A to 50D. Further, the switching operation of the position measurement system described above does not necessarily have to be performed. That is, alignment system ALG and wafer interferometer system (18X)<sub>2</sub>, 18Y) to measure the position information of the alignment mark on the wafer W and the reference mark on the wafer stage WST, and the reticle alignment system and the encoder system to measure the position information of the reference mark on the wafer stage WST. Based on these position information, the position of the wafer stage may be controlled by the encoder system.
0199Further, in the above-described embodiment and modification, the case of switching from the interferometer to the encoder as the switching operation of the position measurement system has been described, but the present invention is not limited to this. For example, when the alignment system ALG is installed at a position sufficiently distant from the projection unit PU, the same area as the above-mentioned head units 46A to 46D is used in the area where the alignment operation using the alignment system ALG is performed. The head unit is arranged in a cross shape around the alignment system ALG. Then, each of the moving scales 44A to 44D has an origin, and at the time of wafer alignment such as EGA, the origin of the coordinate system defined by the combination of these moving scales 44A to 44D (that is, the moving scale 44A ~ The position information of each alignment mark on the wafer W based on the point defined by the origin of 44D) is detected by using the head unit and the moving scales 44A to 44D, and a predetermined calculation is performed based on the detection result. This may be performed to obtain the relative position information of each shot region with respect to the above origin. In this case, at the time of exposure, the origin is detected by using the encoders 50A to 50D, and the acceleration start position for exposing each shot area is used by using the relative position information of each shot area with respect to the above origin. Can be moved to. In this case, the position drift between the head, the projection unit PU, and the alignment system ALG also causes an error, so it is desirable to calibrate this as well.
0200In the above-described embodiment and modification, the positions of the reticle stage RST and the wafer stage WST are controlled by using the above-mentioned encoder system (FIGS. 2, FIG. 3, FIG. 25, FIG. 26) during the wafer exposure operation. However, the position control of the stage using the encoder system is not limited to the exposure operation, and other than the exposure operation, for example, the detection operation of the reticle alignment mark or the reference mark of the reticle stage RST by the reticle alignment system, or the reticle The position of the reticle stage RST may be controlled by using the encoder system shown in FIG. 2 even in the replacement operation. Similarly, for example, in the detection operation of the alignment mark of the wafer W by the alignment system ALG, or in the wafer replacement operation, the position control of the wafer stage WST is performed by using the encoder system shown in FIGS. 3, 25, and 26. You may go. In this case, of course, the above-mentioned switching operation of the position measurement system becomes unnecessary.
0201Here, even when the alignment mark on the wafer W or the reference mark of the wafer stage WST is detected by the alignment system ALG, or when the reference mark of the wafer stage WST is detected by the reticle alignment system, the above-mentioned encoder system (FIGS. 3 and 3). When 25 and FIG. 26) are used, it is preferable to consider the moving range of the wafer stage WST during this detection operation. In particular, each head unit (46A to 46D, 46A to 46D) is also in the mark detection operation performed by moving the wafer stage to the measurement position of the alignment system ALG.<sub>2</sub>) Does not deviate from the corresponding moving scale (diffraction grating), that is, the length (or arrangement) of each head unit in the longitudinal direction does not become impossible to measure the position by the encoder system and the position control of the wafer stage is not interrupted. Etc.), or it is preferable to provide a head unit different from those head units.
0202Further, it depends on the wafer exchange position (including at least one of the load position and the unload position), the exchange position, and the exposure position where the reticle pattern is transferred via the projection optical system PL, or the alignment system ALG. When the above-mentioned encoder system (FIGS. 3, 25, 26) is used while the wafer stage WST is moving from one of the measurement positions where the mark is detected to the other, the wafer replacement position and its replacement operation are similarly performed. Considering the movement range of the wafer stage at the time, set the arrangement, length, etc. of each head unit so that the position measurement by the encoder system is not impossible and the position control of the wafer stage is not interrupted, or they. It is preferable to provide a head unit different from the head unit.
0203Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-214783 and the corresponding US Pat. No. 6,341,007, and International Publication No. 98/40791 and the corresponding US Pat. No. 6,262,796, two Even in a twin wafer stage type exposure apparatus capable of performing an exposure operation and a measurement operation (for example, mark detection by an alignment system) almost in parallel using a wafer stage, the above-mentioned encoder system (FIGS. 3, 25, FIG. It is possible to control the position of each wafer stage using 26). Here, by appropriately setting the arrangement, length, etc. of each head unit not only during the exposure operation but also during the measurement operation, the above-mentioned encoder systems (FIGS. 3, 25, 26) can be used as they are. Although it is possible to control the position of the wafer stage, the above-mentioned head units (46A to 46D, 54A to 54D)<sub>2</sub>), A head unit that can be used during the measurement operation may be provided. For example, four head units arranged in a cross shape centered on the alignment system ALG are provided, and during the above measurement operation, the positions of each wafer stage WST are determined by these head units and the corresponding moving scales (46A to 46D, 52A to 52D). Information may be measured. In the twin wafer stage type exposure apparatus, two or four moving scales (Fig. 3, Fig. 25, Fig. 26) are provided on each of the two wafer stages, and the wafer mounted on one wafer stage is exposed. When the process is completed, the other wafer stage on which the next wafer whose mark is detected at the measurement position is placed is arranged at the exposure position by exchanging with one of the wafer stages. Further, the measurement operation performed in parallel with the exposure operation is not limited to the detection of marks such as wafers by the alignment system, and instead or in combination with it, for example, the surface information (step information, etc.) of the wafer. You may perform detection and the like.
0204In the above description, the position control of the wafer stage using the encoder system is performed at the measurement position or the exchange position, or during the movement of the wafer stage from one of the exposure position, the measurement position, and the exchange position to the other position. When it runs out, it is preferable to control the position of the wafer stage at each of the above positions or during movement by using a measuring device (for example, an interferometer, an encoder, etc.) different from the encoder system.
0205Further, in the above-described embodiment and modification, as disclosed in, for example, International Publication No. 2005/074014, International Publication No. 99/23692, and US Patent No. 6,897,963, measurement is performed separately from the wafer stage. A measurement stage having members (reference marks, sensors, etc.) is provided, and the measurement stage is placed directly under the projection optical system PL by exchanging with the wafer stage during wafer replacement operation, and the characteristics of the exposure device (for example, projection optics). It may be used to measure the imaging characteristics (wave surface aberration, etc.) of the system, the polarization characteristics of the illumination light IL, etc.). In this case, a moving scale may be arranged on the measurement stage as well, and the position of the measurement stage may be controlled by using the encoder system described above. Further, during the exposure operation of the wafer placed on the wafer stage, the measurement stage is retracted to a predetermined position that does not interfere with the wafer stage, and is moved between the retracted position and the exposure position. Therefore, the position can be measured by the encoder system in consideration of the moving range of the measurement stage as well as the wafer stage even at the retracted position or while the retracted position and the exposed position are moving from one to the other. It is preferable to set the arrangement, length, etc. of each head unit so that the position control of the measurement stage is not interrupted due to the inability, or to provide a head unit different from those head units. Alternatively, when the position control of the measurement stage by the encoder system is cut off at the retracted position or during the movement, the position control of the measurement stage is performed using a measurement device (for example, an interferometer, an encoder, etc.) different from the encoder system. It is preferable to do so.
0206Further, in the above-described embodiment and modification, for example, depending on the size of the projection unit PU, the distance between the pair of head units extending in the same direction must be widened, and a specific shot area on the wafer W, For example, during scanning exposure of a shot region located on the outermost periphery, one of the pair of head units may deviate from the corresponding moving scale. As an example, if the projection unit PU becomes slightly larger in FIG. 3, the head unit 46B of the pair of head units 46B and 46D may deviate from the corresponding movement scale 44B. Further, for example, International Publication No. 99/49504, International Publication No. 2004/053955 (corresponding US Patent Application Publication No. 2005/0252506), US Pat. No. 6,952, 253, European Patent Application Publication No. 1420298, International Publication No. 2004/055803, International Publication No. 2004/057590, US Patent Application Publication No. 2006/0231206, US Patent Application Publication No. 2005 / In the immersion type exposure apparatus in which a liquid (for example, pure water) is filled between the projection optical system PL and the wafer, which is disclosed in the specification of 0280791, a nozzle member for supplying the liquid surrounds the projection unit PU. Therefore, it becomes more difficult to arrange the head unit close to the above-mentioned exposure region of the projection optical system PL. Therefore, in the encoder system shown in FIGS. 3 and 26, it is not always necessary to be able to measure two position information in each of the X-axis and Y-axis directions, and two position information in one of the X-axis and Y-axis directions. , And on the other hand, the encoder system (particularly the head unit) may be configured so that one position information can be measured. That is, in the position control of the wafer stage (or measurement stage) by the encoder system, it is not always necessary to use a total of four position information, two each in the X-axis direction and the Y-axis direction. Further, in the immersion type exposure apparatus, for example, as shown in FIG. 27, the liquid repellent plate WRP on the upper surface of the wafer stage WST (or the wafer table WTB) may be made of glass, and a scale pattern may be directly provided on the glass. .. Alternatively, the wafer table may be made of glass. In an immersion exposure apparatus including a wafer stage (or measurement stage) having a moving scale (FIGS. 3, 25, 26) of the above embodiment and a modified example, a liquid repellent film is formed on the surface of the moving scale. It is preferable to keep it.
0207Considering the miniaturization and weight reduction of the wafer stage WST, it is preferable to arrange the moving scale on the wafer stage WST as close as possible to the wafer W, but when it is permissible to enlarge the wafer stage, By enlarging the wafer stage and widening the distance between the pair of moving scales arranged facing each other, a total of four position information is measured, two each in the X-axis and Y-axis directions, at least during the wafer exposure operation. It may be possible. Further, instead of enlarging the wafer stage, for example, a moving scale is provided so that a part of the moving scale protrudes from the wafer stage, or an auxiliary plate provided with at least one moving scale is used to provide the moving scale outside the wafer stage body. By arranging them, the distance between the pair of moving scales arranged so as to face each other may be widened.
0208In addition, prior to controlling the position of the stage by the encoder system, for example, the tilt of the head unit (tilt with respect to the Z-axis direction), the arrangement of the heads in the XY plane (position or spacing, etc.), or the telecentric tilt of the head, etc. It is preferable to measure and use this measurement result in the above position control. Further, for example, it is preferable to measure the amount of displacement or inclination of the moving scale in the Z-axis direction (direction perpendicular to the surface) and use this measurement result in the above position control.
0209The first to third calibration operations of the encoder described in the above embodiment and the modified example and the above-mentioned sequential calibration operation may be performed individually or in combination as appropriate. Further, the stage is moved at a low speed when the position is measured by the encoder system and the interferometer system in the calibration operation described above, but the present invention is not limited to this, and the stage may be moved at the same speed as the scanning exposure as described above. good.
0210Further, in the above-described embodiment and modification, the position control of the reticle stage and the wafer stage is performed by using the encoder system, but the position control is not limited to this, and for example, the position control using the encoder system is performed in one of the reticle stage and the wafer stage. In the other stage, position control using an interferometer system may be performed. Further, in the above-described embodiment and modification, the encoder head unit is arranged above the reticle stage, but the encoder head unit may be arranged below the reticle stage. In this case, the moving scale is also provided on the lower surface side of the reticle stage.
0211Further, in the encoder system of the above-described embodiment and modified examples (FIGS. 3, 25, 26), the plurality of moving scales (44A to 44D, 52A to 52D) are, for example, suction mechanisms such as vacuum chucks or leaf springs, respectively. The wafer stage is fixed to the WST, but the present invention is not limited to this, and for example, screwing or a diffraction grating may be formed directly on the wafer stage. In particular, in the latter case, a diffraction grating may be formed on the table on which the wafer holder is formed, or particularly on the liquid repellent plate in the immersion type exposure apparatus. In both the reticle stage RST and the wafer stage WST, the members forming the diffraction grating (including the above-mentioned moving scale) are made of a low thermal expansion material such as ceramics (for example, Zerodur manufactured by Shot Co., Ltd.). It is preferable to do so. Further, in order to prevent deterioration of measurement accuracy due to adhesion of foreign matter, dirt, etc., for example, the surface may be coated or provided with a cover glass so as to cover at least the diffraction grating. Further, in both the reticle stage RST and the wafer stage WST, the diffraction grating is continuously formed over almost the entire longitudinal direction of each moving scale. For example, the diffraction grating is divided into a plurality of regions. It may be formed intermittently, or each movement scale may be composed of a plurality of scales.
0212In the above-described embodiment and modification, especially in the encoder system of FIG. 3, a pair of moving scales 44A and 44C used for measuring the Y-axis direction position and a pair of moving scales 44B used for measuring the X-axis direction position. , 44D are provided on the wafer stage WST, and correspondingly, a pair of head units 46A and 46C 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 46B , 46D is illustrated on one side and the other side of the projection optical system PL in the Y-axis direction. However, not limited to this, at least one of the moving scales 44A and 44C for measuring the position in the Y-axis direction and the moving scales 44B and 44D for measuring the position in the X-axis direction is not a pair but only one on the wafer stage WST. Alternatively, at least one of the pair of head units 46A and 46C and the pair of head units 46B and 46D may be provided instead of the pair. This also applies to the encoder system shown in FIG. Further, the extension direction of the moving 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.
0213Further, in the above-described embodiment and modification, the configuration of the wafer interferometer system 18 is not limited to FIG. 3, and for example, when the head unit is arranged in the alignment system ALG (measurement position), the wafer X interference occurs. 18X in total<sub>2</sub>Does not have to be equipped with Wafer X Interferometer 18X<sub>2</sub>May be configured by, for example, a multi-axis interferometer similar to the wafer Y interferometer 18Y so that rotation information (eg yawing and rolling) as well as the X position of the wafer stage WST can be measured. Also, wafer X interferometer 18X<sub>1</sub>Wafer Y interferometer 18Y is used as a 1-axis interferometer, and wafer X interferometer 18X<sub>1</sub>May be a multi-axis interferometer similar to the wafer Y interferometer 18Y. The multi-axis interferometer may be capable of measuring only yawing as rotation information. In addition, Wafer X Interferometer 18X<sub>1</sub>And one of the wafer Y interferometer 18Y may be capable of measuring only one rotation information (rolling or pitching). That is, the wafer interferometer system 18 of the present embodiment may be capable of measuring at least position information in the X-axis and Y-axis directions and rotation information (yaw) in the θz direction during the wafer exposure operation.
0214In the above embodiment, the case where the present invention is applied to a scanning stepper has been described, but the present invention is not limited to this, and the present invention may be applied to a static exposure device such as a stepper. Even with a stepper, a position measurement error due to air fluctuation is different from the case where the position of the stage on which the object to be exposed is mounted is measured with an encoder and the position of the stage is measured with an interferometer. Can be reduced to almost zero. In addition, the stage can be positioned with high accuracy based on the correction information that corrects the short-term fluctuation of the measured value of this encoder using the measured value of the interferometer and the measured value of the encoder, and the reticle is highly accurate. The pattern can be transferred onto the object. 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. As such, 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 illumination light IL is not limited to ArF excimer laser light (wavelength 193 nm), but is ultraviolet light such as KrF excimer laser light (wavelength 248 nm), or F.<sub>2</sub>It may be vacuum ultraviolet light such as laser light (wavelength 157 nm). As vacuum ultraviolet light, for example, as disclosed in International Publication No. 99/46835 (corresponding US patent No. 7,023,610), a single infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser. 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 form a pattern of 70 nm or less, EUV (Extreme Ultraviolet) light in the soft X-ray region (for example, wavelength range of 5 to 15 nm) is generated using a SOR or 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 or dimming pattern) is formed on a light-transmitting substrate is used, but instead of this reticle, a light-transmitting mask (reticle) is used. 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 (also called a 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 calibrating using the measured value of the interferometer in the same manner as described above, the same effect as that of the above embodiment can be obtained.
0219Further, for example, as disclosed in International Publication No. 2001/035168, an exposure apparatus (lithographic system) that forms a line-and-space pattern on a wafer W by forming interference fringes on the wafer W. The present invention can also 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 double-headed projection optical system, and 1 The present invention can also be applied to an exposure apparatus that double-exposes one shot area on a wafer at almost the same time by performing multiple scan exposures.
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, and the glass plate, ceramic substrate, mask blanks, film member, etc., etc. It may be an object of. Further, the shape of the object is not limited to a circle, but may be another shape such as a rectangle.
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, or an image pickup device. It can be widely applied to exposure equipment for manufacturing (CCD, etc.), micromachines, DNA chips, etc. 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 and the like, glass substrates or silicon wafers and the like are used. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a wafer.
0224The present invention is not limited to an exposure apparatus, but may be a moving stage such as a processing apparatus for other substrates (for example, a laser repair apparatus, a substrate inspection apparatus, etc.), a sample positioning apparatus in another precision machine, a wire bonding apparatus, or the like. It can be widely applied to the equipment provided.
0225The semiconductor device is formed on a mask by a step of designing the function and performance of the device, a step of manufacturing a reticle based on this design step, a step of manufacturing a wafer from a silicon material, and an exposure apparatus of the above embodiment. It is manufactured through a lithography step of transferring a pattern onto a photosensitive object, a device assembly step (including a dicing step, a bonding step, and a packaging step), an inspection step, and the like. In this case, since the exposure apparatus of the above embodiment is used in the lithography step, a device having a high degree of integration can be manufactured with a high yield.
0226Further, the exposure apparatus (pattern forming apparatus) of the above-described embodiment and the modified example provides various subsystems including each component listed in the claims of the present application with predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Manufactured by assembling to keep. 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.
022711 ... Reticle stage drive system, 16y ... Reticle Y interferometer, 18X<sub>1</sub>, 18X<sub>2</sub>... Wafer X Interferometer, 18Y ... Wafer Y Interferometer, 20 ... Main Controller, 24A ... Moving Scale, 26A<sub>1</sub>, 26B<sub>1</sub>... Y encoder, 27 ... Wafer stage drive system, 32 ... 1st column, 50A, 50C ... Y linear encoder, 50B, 50D ... X linear encoder, 100 ... exposure equipment, ALG ... alignment system, PL ... projection optical system, RST ... reticle stage, WST ... wafer stage, IL ... illumination light, W ... wafer, R ... reticle.
27 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11 Sheet 12 Sheet 13 Sheet 14 Sheet 15 Sheet 16 Sheet 17 Sheet 18 Sheet 19 Sheet 20 Sheet 21 Sheet 22 Sheet 23 Sheet 24 Sheet 25 Sheet 26 Sheet 27
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| SG2014011563A | Singapore | A | |
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| EP2765458A3 | European Patent Office (EPO) | A3 | |
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| KR101477468B1 | Republic of Korea | B1 | |
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| EP2752714B1 | European Patent Office (EPO) | B1 | |
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| EP2752714B8 | European Patent Office (EPO) | B8 | |
| EP2801864B8 | European Patent Office (EPO) | B8 | |
| JP5804299B2 | Japan | B2 | |
| HK1204087A1 | Hong Kong, China | A1 | |
| TWI508132B | Taiwan Province of China | B | |
| TWI508133B | Taiwan Province of China | B | |
| EP2963498A1 | European Patent Office (EPO) | A1 | |
| TW201603117A | Taiwan Province of China | A | |
| SG10201510758QA | Singapore | A | |
| JP5896255B2 | Japan | B2 | |
| EP2765458B1 | European Patent Office (EPO) | B1 | |
| EP2857902B1 | European Patent Office (EPO) | B1 | |
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| EP3043208A1 | European Patent Office (EPO) | A1 | |
| TW201628064A | Taiwan Province of China | A | |
| JP5967390B2This record | Japan | B2 | |
| US9423702B2 | United States of America | B2 | |
| US9423703B2 | United States of America | B2 | |
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| EP2963498B8 | European Patent Office (EPO) | B8 | |
| JP2017142528A | Japan | A |
8 legal events, as the office reported them to INPADOC
Over the term
Point at a mark for the eventEvents
| Event | Code | |
|---|---|---|
| Cancellation because of no payment of annual feesLAPS | LAPS | |
| Receipt of annual feesJAPANESE INTERMEDIATE CODE: R250R250 | R250 | |
| Certificate of patent or registration of utility modelJAPANESE INTERMEDIATE CODE: R150R150 | R150 | |
| First payment of annual fees (during grant procedure)JAPANESE INTERMEDIATE CODE: A61A61 | A61 | |
| Written decision to grant a patent or to grant a registration (utility model)JAPANESE INTERMEDIATE CODE: A01A01 | A01 | |
| Decision of grant or rejection writtenTRDD | TRDD | |
| Written amendmentJAPANESE INTERMEDIATE CODE: A523A521 | A521 | |
| Notification of reasons for refusalJAPANESE INTERMEDIATE CODE: A131A131 | A131 |
Numbers
- Publication
- 5967390
- Application
- 97003
Titles2
- Japanese
- 液浸露光装置及び液浸露光方法、並びにデバイス製造方法
- English
- Immersion exposure equipment and immersion exposure method, and device manufacturing method
Classification
- CPC, 16
- G03F7/70516
- G03F7/70725
- G03F7/70716
- G03F7/70341
- G03F7/70775
- Y10T29/49826
- G03F7/70758
- G03F7/706837
- G03F7/7085
- G01B11/27
- G01D5/266
- G03F7/70975
- G01D5/26
- G01D18/002
- G03F7/70141
- G03F7/70483
- IPC, 4
- G03F9 00
- G03F7 20
- G01B11 00
- H10P72 50
