Method and device for the correction of imaging defects

[0001] The present invention relates to a lithographic apparatus and a device manufacturing method using the lithographic apparatus.

[0002] A lithographic apparatus is a machine that applies a desired pattern on a substrate, usually on a target portion of the substrate. Lithographic equipment can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, also called a mask or reticle, can be used to generate the circuit patterns to be formed on the individual layers of the IC. This pattern can be transferred onto a target portion (eg, including a portion of one or more dies) on a substrate (eg, a silicon wafer). Pattern transfer is generally done by forming an image on a layer of radiation sensitive material (resist) provided on the substrate. Generally, a single substrate contains a network of adjacent target portions that are continuously patterned. Known lithographic devices include a so-called stepper, which illuminates each target portion by exposing the entire pattern onto the target portion at once, and scans the pattern in a given direction (scan direction) with a radiating beam. However, it includes a so-called scanner in which each target portion is illuminated by scanning the substrate parallel to or antiparallel to that direction in synchronization with it. By imprinting the pattern on the substrate, it is also possible to transfer the pattern from the patterning device to the substrate.

[0003] Efforts to follow the known Moore's Law, which is intended to quadruple the density of components in integrated circuits every three years, drive continuous improvements in lithographic equipment. ing. The critical dimension of a feature that can be printed using a lithographic device is proportional to the wavelength of the exposure radiation used divided by the numerical aperture NA of the device's projection system. Therefore, there is a tendency to increase the numerical aperture of the projection system more and more. However, as the numerical aperture of the projection system increases, so does its size and complexity. It also reduces the depth of focus DOF, making it more difficult to image difficult patterns, especially in contact hole arrays.

<p>[0004] Therefore, it is desirable to provide a lithography apparatus with improved imaging capability.</p>

<p>[0005] According to one embodiment of the invention, a projection system configured to project an image of a pattern onto a substrate, such as projecting a radiated beam along an optical path that includes at least one pupil plane. A projection system containing a plurality of optical elements forming an optical system constructed in an optical system and interchangeable optical elements are moved into and out of an optical path in the pupil plane or a certain pupil plane of the optical system. A lithography projection apparatus is provided, which includes a transport mechanism configured to allow the optics.</p><p>[0006] According to one embodiment of the present invention, it is a projection system configured to project an image of a pattern onto a substrate, and is configured to project a radiation beam along an optical path including an optical path. A projection system with multiple optical elements forming the optical system and interchangeable optical elements with peripheral dimensions that closely match the relevant parts of the patterning device standard into the optical path in the pupil plane of the optical system. Also provided is a lithography projection apparatus including a transfer mechanism configured to move from the inside to the outside.</p><p>[0007] According to one embodiment of the present invention, a lithographic projection apparatus is used that includes a patterning device and a projection system having at least one pupil surface configured to project an image of the patterning device onto a substrate. Device manufacturing methods, such as loading a pattern onto a patterning device, placing interchangeable optics in its pupil plane or within a pupil plane, projecting an image of the pattern onto a substrate, and patterning the pattern. Methods are provided that include removing from the device and removing interchangeable optical elements from the pupil plane.</p><p>[0008] According to one embodiment of the present invention, a pattern support for supporting the patterning device and a projection system having a pupil surface and configured to project an image of the pattern of the patterning device onto a substrate. A device manufacturing method that uses a lithography projection device that includes, loading a patterning device onto a pattern support, placing interchangeable optics in the pupil, and projecting an image of the pattern onto a substrate. The interchangeable optics have peripheral dimensions that closely match the relevant parts of the patterning device standard, including removing the patterning device from the pattern support and removing the interchangeable optics from the pupil plane. , The method is provided.</p><p>[0009] According to one embodiment of the invention, interchangeable optics configured to be selectively located within the pupil plane of the projection system of a lithographic apparatus, the relevant portion of the reticle standard. Interchangeable optical elements with external dimensions commensurate with are provided.</p><p>[0010] According to one embodiment of the invention, interchangeable optics configured to be selectively located within the pupil plane of the projection system of the lithography system, which are not rotationally symmetric. The element is provided.</p><p>[0011] Next, as only one example, embodiments of the present invention will be described with reference to the accompanying schematics. In those schematics, the corresponding reference symbols indicate the corresponding parts.</p>

[0026] FIG. 1 schematically shows a lithography apparatus according to an embodiment of the present invention. The device has several structures that support an irradiation system (illuminator) IL configured to adjust the emission beam B (eg UV or DUV emission) and a patterning device (eg mask) MA. It has a structure that holds a support structure (for example, a mask table) MT connected to a first positioner PM configured to accurately position the patterning device according to parameters, and a substrate (for example, a resist coated wafer) W. A substrate table (eg, a wafer table) WT connected to a second positioner PW configured to accurately position the substrate according to some parameters and a pattern imparted to the radiated beam B by the patterning device MA. Includes a projection system (eg, a refraction projection lens system) PS configured to project onto a target portion C (eg, including one or more dies) of substrate W.

[0027] Irradiation systems can be used to guide, shape, or control radiation, including refraction-type, reflection-type, magnetic-type, electromagnetic-type, electrostatic-type, or other types of optical components, or any combination thereof. Can include types of optical components. The support structure supports the patterning device, i.e. supports its weight. The support structure holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as whether the patterning device is held in a vacuum environment. The support structure can use mechanical clamping techniques, vacuum clamping techniques, electrostatic clamping techniques, or other clamping techniques to hold the patterning device. The support structure may be, for example, a frame or a table, which may be fixed or movable as needed. The support structure can allow the patterning device to be in the desired position, eg, with respect to the projection system. When the term "reticle" or "mask" is used herein, it can be considered as a synonym for the more general term "patterning device".

[0028] The term "patterning device" as used herein can be used to impart a pattern within a cross section of a radiated beam, such as to form a pattern within a target portion of a substrate. It should be broadly interpreted as referring to any device. It should be noted that the pattern imparted to the radiated beam may not exactly match the desired pattern within the target portion of the substrate, for example if the pattern contains phase shift features or so-called assist features. In general, the pattern applied to the radiated beam corresponds to a particular functional layer within a device formed within the target portion, such as an integrated circuit.

[0029] The patterning device may be a transmissive type or a reflective type. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are known in lithography, and masks include mask types such as binary, Alternating phase shift, attenuation phase shift, and various hybrid mask types. An example of a programmable mirror array uses a matrix array of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirror imparts a pattern within the radiated beam reflected by the mirror matrix.

[0030] As used herein, the term "projection system" refers to refraction optical systems, suitable for the exposure radiation used, or for other factors, such as the use of immersion liquid or the use of vacuum. It should be broadly interpreted as including any type of projection system, including reflective optical systems, catadioptric optical systems, magnetic optical systems, electromagnetic optical systems, and electrostatic optical systems, or any combination thereof. Is. When the term "projection lens" is used herein, it can be considered as a synonym for the more general term "projection system".

[0031] As shown here, this device is transparent (eg, using a transparent mask). Alternatively, the device may be reflective (eg, using a programmable mirror array of the type described above, or using a reflective mask).

[0032] The lithographic apparatus may be of a type having two or more (dual stage) substrate tables (and / or two or more mask tables). In such "multi-stage" machines, additional tables can be used simultaneously, or one or more other tables are exposed while performing preliminary stages on one or more tables. Can also be used for.

The lithography apparatus may be of a type in which at least a part of the substrate can be covered with a liquid having a relatively high refractive index, for example, water so as to fill the space between the projection system and the substrate. Immersion liquid can also be applied to other spaces within the lithographic apparatus, such as between the mask and the projection system. Immersion techniques are known in the art by increasing the numerical aperture of the projection system. The term "immersion" does not mean here that a structure such as a substrate must be immersed in a liquid, but that the liquid is between the projection system and the substrate during exposure. It just means.

[0034] Referring to FIG. 1, the illuminator IL receives a radiated beam from the source SO. The radiation source and the lithographic apparatus can be separate, for example, when the radiation source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiated beam uses a beam feeding system BD, including, for example, a suitable induction mirror and / or beam magnifier. It is passed from the radiation source SO to the illuminator IL. In other cases, for example, when the source is a mercury lamp, the source can be part of a lithographic device. The source SO and the illuminator IL, together with the beam supply system BD, can be referred to as the radiation system, if desired.

The illuminator IL can include an adjuster AD for adjusting the angular intensity distribution of the radiated beam. In general, the intensity distribution within the pupil plane of the illuminator can be adjusted at least in the outer and / or inner radial ranges (commonly referred to as σ-outer and σ-inner, respectively). In addition, the illuminator IL can include a variety of other components such as integrator IN and condenser lens CO. The illuminator can be used to adjust the radiated beam to have the desired uniformity and intensity distribution within its cross section.

[0036] The radiated beam B is incident on a patterning device (eg, mask MA) held on a support structure (eg, mask table MT) and patterned by the patterning device. The radiated beam B that has passed through the mask MA passes through the projection system PS, and the projection system PS focuses the beam on the target portion C of the substrate W. A second positioner PW and a position sensor IF (eg, an interferometer device, linear encoder, or capacitive sensor) are used to position the board table WT, for example, to position various target portions C in the path of the radiation beam B. It can be moved accurately. Similarly, using the first positioner PM and another position sensor (not explicitly shown in Figure 1), the mask MA is removed, for example, from the mask library mechanically, or during scanning. , Can be accurately positioned with respect to the path of the radiated beam B. In general, the movement of the mask table MT can be realized by using a long stroke module (coarse movement positioning) and a short stroke module (fine movement positioning) that form a part of the first positioner PM. Similarly, movement of the board table WT can be achieved using long stroke modules and short stroke modules that form part of the second positioner PW. In the case of steppers (as opposed to scanners), the mask table MT may be connected only to the short stroke actuator or fixed. The mask MA and the substrate W can be aligned using the mask alignment markers M1 and M2 and the substrate alignment markers P1 and P2. Although the illustrated substrate alignment markers occupy a dedicated target portion, they can also be placed within the distance between the target portions (they are known as scribe lane alignment markers). Similarly, in situations where there are two or more dies on the mask MA, a mask alignment marker is placed between the dies.

[0037] The illustrated device may be used in at least one of the following modes:

[0038] In step mode, the entire pattern applied to the radiated beam is projected onto the target portion C at once (ie, single static exposure), with the mask table MT and substrate table WT essentially fixed. ). The substrate table WT is then moved in the X and / or Y directions so that the various target portions C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

[0039] In scan mode, the mask table MT and the substrate table WT are synchronously scanned and the pattern applied to the emitted beam is projected onto the target portion C (ie, single dynamic exposure). The speed and direction of the substrate table WT with respect to the mask table MT can be determined by the magnification (reduction ratio) of the projection system PS and the inversion characteristics of the image. In scan mode, the maximum size of the exposure field limits the width of the target area (in the non-scan direction) in a single dynamic exposure, and the length of the scan motion determines the height of the target area (in the scan direction).

[0040] In another mode, the mask table MT holding the programmable patterning device remains essentially fixed, the pattern applied to the radiated beam is projected onto the target portion C, and the substrate table WT moves. Or it will be scanned. In this mode, pulse sources are commonly used and programmable patterning devices are updated as needed after each movement of the substrate table WT or between successive radiated pulses during a scan. This mode of operation can be easily applied to maskless lithography utilizing programmable patterning devices such as the types of programmable mirror arrays described above.

[0041] Combinations and / or variations of the above-mentioned usage modes, or completely different usage modes may be used.

As shown in FIG. 2, the projection system PS is one or more Fourier conjugates of the object plane on which the patterning device MA is located and the image plane on which the substrate W is located. Has a surface PP. Such a surface is known as the pupil surface. By arranging the optical element in the pupil plane, it is possible to effectively improve the projected image. For example, the contrast of the image can be improved by placing a filter in the pupil plane to block or attenuate the 0th order of the radiation diffracted by the pattern. However, the shape of the element, eg, the filter, required to give a useful improvement in image quality depends on the projected pattern and / or the irradiation settings used. For example, the zero-order size and position varies with the pitch of the lines in the pattern and the position of any off-axis poles in the illumination distribution.

Therefore, in order to take advantage of the opportunity to place elements within the pupil plane, change the elements within the pupil plane each time the imaged pattern and / or the irradiation settings used change. It is desirable to be able to. However, existing projection systems are fairly complex and susceptible to pollution. Therefore, they are a slightly overloaded, clean flushing gas, eg N, for example 3 mbar.₂Is housed in a sealed housing that is commonly supplied. Some projection systems have elements that can be replaced several times, for example four times, during the useful life of the projection system to compensate for the aging of the lens. To replace such elements, the housing of the projection system is opened and those elements are generally performed by one of ordinary skill in the art under extremely severe clean room conditions. Performing this task more frequently than required is undesirable due to the risk of contaminating the elements of the projection system and the time it takes to perform the task.

[0044] In one embodiment of the invention is provided a transport mechanism 30 for allowing the optical element 10 to be replaced within the pupil plane PP of the projection system without opening the projection system housing 20. This is shown in detail in FIGS. 3 to 8.

Focusing first on FIG. 3 and FIG. 4, which is an enlarged view of the annular portion of FIG. 3, the transport mechanism 30 includes a slider 31 having a recess 35 into which a replaceable optical element 10 is mounted. You can see that it is. The slider 31 projects through an opening 21 in the wall surface 22 of the housing 20 of the projection system PS, thus projecting the replaceable optical element 10 into the projection system by inserting or pulling out the slider 31. It can be placed in or withdrawn from the path of the radiating beam.

[0046] FIGS. 4, 5 and 6 show in more detail that the opening 21 is defined in more detail by a lip piece 23 that projects outward from the wall surface 22 and snugly surrounds the slider 31. Note that in FIG. 4, the slider 31 is shown partially pulled out. To minimize the leakage of flushing gas from the housing 22, the opening defined by the lip piece 23 is very closely conformal to the shape of the slider 31 and is also extremely long. The gap length l and height w were determined to provide sufficient flow resistance to reduce gas leaks to acceptable levels that could depend on the cost of housing overpressure and flushing gas.₂, H₂It is also determined to ensure an outward gas flow rate that is fast enough to prevent the ingress of pollutants such as O and HC. The length may be in the range of about 50 to 500 mm, preferably about 200 to 500 mm, and the width may be in the range of about 0.05 to 0.2 mm, preferably about 0.075 to 0.15 mm. The resulting "seal" is leaky non-contact and therefore does not itself become a source of pollution.

It can be seen that the side surface portion 32 of the slider 31 is higher in height than the inner portion. This provides additional longitudinal stiffness for the slider and additional space 24 for the bearings, while allowing the aperture for the projection lens in the housing to be kept as small as possible, a pupil filter. Allows for a secure fit within the narrow gap between the lens elements. It is desirable for the slider to be very stiff in order to avoid the need to widen the opening 21 to accommodate the deflection within the slider 31.

[0048] The slider is supported by a lip piece 23 connected to housing 20. Since the slider is fixed during exposure, there is no transmission of vibration to the projection system. However, it is desirable that there is no physical contact between the slider and the lip piece to prevent the formation of contaminant particles that can occur when two objects rub against each other.

A convenient way to support the slider 31 is by using gas bearings (not shown in FIGS. 3-8), which can provide very low friction support. The gas bearing may be provided in the lip piece 23 or may be provided as an extension portion of the lip piece 23. When using gas bearings near the opening 21, it is convenient to use the same gas used to flush the housing 20, which further reduces the risk of contamination of the projection system. There is an advantage.

[0050] FIGS. 7 and 8 show a slider 31 that holds the replaceable optical element 10 in the fully inserted (FIG. 7) and fully retracted (FIG. 8) positions. In the fully retracted position, it can be seen that the replaceable element 10 is in a position where it can be removed from the slider and replaced with another element, for example for use with different patterns or different irradiation settings. However, the end portion 33 of the slider 31 remains within the lip piece 23 so as to maintain an effective seal of the housing 20.

Actuators for slider 31 are not shown in FIGS. 3-8, but any suitable actuator with the desired motion and power range, such as a linear motor, voice coil motor, belt driven, or pneumatic actuator. Can be used. Since the projection system is susceptible to changes in vibration and temperature, it is desirable to use actuators that do not induce vibration and dissipate heat relatively low, as described above. The actuator can be placed outside the clean environment and the motion can be supplied using a suitable mechanism.

[0052] The replaceable element 10 remains within the slider 31 when inside the projection system, and the replacement of the element takes place outside the projection system when the slider is in the fully retracted position. Please note. This avoids the need to provide a mechanism within the projection system and thus avoids the possibility of contamination. The exchange mechanism according to the embodiment of the present invention will be described below.

[0053] FIGS. 9 and 10 show different embodiments of the above embodiments in the inserted and pulled out positions, respectively. Actuators and bearing units 34, including gas bearings or roller bearings, are shown adjacent to the lip piece 23, but preferably the lip to avoid heat and / or vibration transfer to the projection system. Do not touch piece 23.

As an alternative to the slider and leaky seal configuration, an airlock configuration with a clean interior of the housing 20 and separate doors to the outside world can be provided. A mechanism, such as a grip in the airlock, receives the optics through the outer door, which is then closed. The inner door opens and the mechanism places the optics in the pupil. A flushing process can be performed after closing the outer door and before opening the inner door.

[0055] Replaceable optical elements 10 according to one embodiment of the present invention are shown in FIGS. 11 and 12. Element 10 is square and its sides a and b are equal to the length specified in the mask (reticle) standard, eg, approximately equal to 5, 6 or 9 inches (127, 152.4 or 228.6 mm). Includes frame 11. A related standard is the SEMI standard P1-83 (available from www.semi.org), which states that a 5-inch reticle is 4.97 inches (126.24 mm) to 5 inches (127 mm). It is usually possible to have aspects in the range of. In one embodiment, the thickness of the frame also meets the thickness specified by the same standard, eg, about 0.09 inch (2.29 mm) or about 0.12 inch (3.05 mm), but to the one specified by the standard. It is possible to deviate from the standard thickness without losing the benefits of having equal sides. Specifically, the pupil filter can meet the standard at the edges to allow it to be housed in a standard SMIF box, but can be thicker in the middle. it can. The width of the frame is preferably sufficient to allow the frame to be gripped by a standard reticle handling device, but the frame is a projection system in which the central area within it is used with the frame. It should not be wide enough to be narrower than the pupillary surface of. The frame may also be provided with human-readable and machine-readable markings (eg, barcodes) at standard positions specified for the reticle in industry or proprietary standards.

[0056] The optical element itself is mounted within the frame. In the illustrated embodiment, the optical element includes a binary pupil filter made of a metal (eg, aluminum) sheet 12 having an annular aperture 13. Again, metal, preferably aluminum ribs 15 support the central piece 14. The sheet 12, ribs 15, and central piece 14 are all provided with an antireflection coating that is effective at the wavelength of the exposure radiation used. The pupil filter may be monolithic, i.e., a standard shaped frame with inserts that can be easily formed into the desired shape.

The effect when the illustrated filter is placed in the pupil plane of the projection system blurs the central 0th order of the diffracted radiation and allows at least one higher order to pass through. That is, it increases the contrast in the projected image, especially when imaging contact holes. To do this correctly, in one embodiment, the inner and outer radii of the annular aperture are preferably determined for a given pattern to be imaged and / or for a given irradiation setting. Appropriate values can be determined by simulation or experiment.

Other shapes of the binary filter can be formed by providing suitable openings in the metal sheet and support ribs. The filter can also be formed by providing a locally opaque layer on the transparent substrate, eg, by providing chromium on quartz and / or by varying the thickness of the transparent substrate for phase correction. ..

A non-rotational symmetric pupil filter can be used to correct image asymmetry, such as horizontal and vertical HV CD offsets. With proper design of the pupil filter, this effect can be tuned as a function of pitch. By exposing features such as contact holes with an elliptical filter, it can be possible to reduce the amount of bias on the mask. This allows more chrome to remain between the holes, while creating less elliptical contact holes, reducing mask costs and improving resolution. Other non-rotating symmetric pupil filters can be used to filter the selected diffraction order in a particular direction.

[0060] Rotational symmetric pupil filters can also be used to improve proximity matching between machines and to provide smaller NA values than can otherwise be achieved.

[0061] FIGS. 13 to 15 show a replacement mechanism 40 for attaching and detaching a replaceable optical element to and from the slider 31, according to an embodiment of the present invention. As can be seen from FIG. 13, the switching mechanism 40 is provided adjacent to the projection system PS, but in one embodiment, the metrology or reference frame is preferably thermally and mechanically contained within the projection system PS and the apparatus. If there is, it will be separated from it. In one embodiment, the replaceable optics are preferably Standard Mechanical for reticle storage and transport containers. It is stored in a transport box 41 that complies with the InterFace (SMIF) standard. Such containers can be attached to and detached from the elevator platform 42 either manually or by known automated handling devices. A known type of grip 43 is used to move the replaceable optical element between the slider 31 and the container 41. The grip 43 is mounted on the X-drive 45 by the arm 44, and the X-drive is mounted on the Y-drive 46. Thus, as shown in FIGS. 14 and 15, the grip can move in two directions to remove the replaceable optical element 10 from the container 41 and place it in the recess 35 within the slider 31. The reverse is also true. The arm 44 may include an actuator to provide any desired movement in the Z direction (perpendicular to X and Y) to pick up the element and release it into the recess. The elevator platform 42 moves vertically by a known mechanism 47 to provide an optical element or an empty slot in the grip 43.

[0062] Container 41 acts as a local buffer for optical elements used in lots processed by the device. In many cases, each optical element 10 is optimized for a particular mask pattern, so it is desirable to have a buffer in the device that has the same storage capacity as the buffer for the corresponding mask. In that case, the operator can load a set of masks and the corresponding optics at the same time. It is also desirable that the replacement of the optics be performed at the same time as the replacement of the mask.

[0063] Figure 16 shows a modified exchange mechanism designed for smaller spaces. Most of this exchange mechanism is the same as that shown in FIGS. 13-15, but the X-drive 45'and Y-drive 46' have been modified to accommodate a smaller volume, omitting the arm 44. It has been done.

[0064] An additional alternative exchange mechanism 140 is shown in FIG. In this embodiment, instead of the SMIF box, rack 141 is used, which opens on two sides to store and buffer the pupil filter. The number of slots provided in rack 141 depends on the height available, but may be, for example, 4 or 5. The grip 143 is movable with two degrees of freedom, Z and Rz, to move the pupil filter from the slider 31 when in the replacement position and from the storage rack 141. The grip 143 is initially under the pupil filter in the slider, lifts the pupil filter out of the slider, then rotates to place the pupil filter in rack 141, and finally lowers to place the pupil filter in rack 141. Place on the support of. Additional cutouts can be provided within the slider to accommodate this movement. The actuator for the grip 143 is located outside the clean environment and is a leaky seal consisting of differential gas bearings. It can be supplied via a bellows, which is a seal). The grip does not include any active grip mechanism such as a vacuum clamp or electromagnet, but is passive and may simply lift the pupil filter. Rack 141 can use mechanisms that allow accurate placement within the slider, such as a ball in the v-groove for accurate placement of the pupil filter.

[0065] In any of the transport systems described above, an additional pupil filter handling device or grip can be provided above the position where the pupil filter emerges from the housing 20. As soon as the "old" pupil filter emerges from the housing 20 during the pupil filter replacement, an additional grip removes it from the slider, thereby removing the "new" pupil filter previously removed from storage by the grip 43. , Can be placed directly on the slider 31. This allows both the return of the "old" pupil filter to storage and the preselection of the "new" pupil filter to occur at the same time as the exposure, minimizing the time it takes to replace the pupil filter. ..

[0066] In a further alternative not shown, which is particularly useful in embodiments where the interchangeable optics are the same size as the mask, the mask and the interchangeable optics are the same or adjacent, eg, SMIF box. A common handling system can be used to transport the mask to the mask stage and the replaceable optics to the transport mechanism, which can be stored together in the container.

[0067] In devices with a mask stage capable of holding two masks, which is beneficial, which allows for faster double exposure performance, the two can be exchanged between masks as quickly as possible. It is desirable to have a slider that can receive the optical elements so that they can be replaced. Such a configuration is shown in FIG. In this embodiment, two load / unload positions 241, 242 for the pupil filter and corresponding transport mechanisms are provided on both sides of the projection system PS. The drive mechanism 232 for the slider 231 includes a rod 233 penetrating an opening in the housing 20 and a bearing 234 for the slider 231.

The entire transport and exchange mechanism is a clean, pure N to prevent contamination of replaceable optics that can be transported into the projection system.₂Can be housed in a closed compartment that is purged with.

[0069] If the projection system has multiple pupil planes, interchangeable optical elements can be provided in any or all pupil planes, as desired and conveniently. In one embodiment of the present invention, the pupil surface closest to the imaged pattern has a size equivalent to that of the pattern and is therefore found to be most convenient.

[0070] It will be appreciated that the transport mechanism described above can be used in other embodiments of the invention to replace any type of optical element within the projection system. For example, the transport mechanism, in one embodiment, replaces a lens, a mirror, or an optical element that includes a combination of various types of optical components, including refracting, reflective, magnetic, electromagnetic, and electrostatic. Can be used for.

[0071] Although specific description may be given here for the use of lithographic devices in the manufacture of ICs, the lithographic devices described herein include induction patterns for integrated optical systems, magnetic domain memories. And it should be understood that there are other application areas such as detection patterns, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads and the like. In the context of such alternative applications, when the terms "wafer" or "die" are used herein, they are considered synonymous with the more general terms "base" or "target portion", respectively. Those skilled in the art will understand that they can. The substrates referred to herein are processed before or after exposure, eg, within a track (generally a tool that provides a layer of resist to the substrate and develops the resist after exposure), metrology tools, and / or inspection tools. can do. Where applicable, the disclosure herein can be applied to such substrate processing tools, as well as other substrate processing tools. Further, the substrate can be processed more than once, for example to form a multilayer IC, and therefore the term substrate as used herein may also refer to a substrate that already contains multiple treated layers. is there.

[0072] In the context of optical lithography, the use of embodiments of the invention may have been specifically described above, but the present invention is described in other applications, such as imprint lithography. It will be appreciated that it can be used in and, where the context allows, is not limited to optical lithography. In imprint lithography, topography within the patterning device defines the pattern formed on the substrate. The topography of the patterning device can be pushed into a layer of resist fed to the substrate, after which the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist has been cured, the patterning device is transferred from it leaving a pattern in the resist.

[0073] As used herein, the terms "radiation" and "beam" are ultraviolet (eg, having wavelengths of about 365, 355, 248, 193, 157 or 126 nm, or close to them). Includes all types of electromagnetic radiation, including UV) radiation, and extreme ultraviolet (EUV) radiation (eg, having wavelengths in the range of 5-20 nm), as well as particle beams such as ion or electron beams.

[0074] The term "lens" refers to any one or combination of various types of optical components, including refracting, reflective, magnetic, electromagnetic, and electrostatic, where the context allows. There is.

Although the specific embodiments of the present invention have been described above, it will be understood that the present invention can be carried out by a method other than those described above. For example, the present invention is in the form of a computer program containing one or more sequences of machine-readable instructions describing the methods disclosed above, or a data storage medium (eg, a semiconductor memory) that stores such computer programs. , Magnetic or optical disc).

[0076] The above description is for illustration purposes only, without limitation. Therefore, it will be apparent to those skilled in the art that modifications can be made to the present invention as described without departing from the appended claims.

<figref num="1">[0012] It is a figure which shows the lithography apparatus by one Embodiment of this invention.</figref><figref num="2">[0013] It is a figure which shows the projection system of the apparatus of FIG.</figref><figref num="3">[0014] A side sectional view of a portion of the projection system of the device of FIG. 1 showing interchangeable optical elements.</figref><figref num="4">[0015] FIG. 3 is an enlarged view of a portion of FIG. 3 showing a partially extracted, magnified optical element.</figref><figref num="5">[0016] FIG. 6 is a front view of a portion of the projection system of the device of FIG. 1 corresponding to FIG.</figref><figref num="6">[0017] It is an enlarged view of a part of FIG.</figref><figref num="7">[0018] Corresponding to FIG. 3, it is a diagram showing a position where a replaceable optical element is completely inserted.</figref><figref num="8">[0018] Corresponding to FIG. 3, it is a diagram showing a position where a replaceable optical element is completely pulled out.</figref><figref num="9">[0019] FIG. 6 is a perspective view of a modified form of the transport mechanism according to an embodiment of the present invention.</figref><figref num="10">[0019] Another perspective view of a modified form of the transport mechanism according to one embodiment of the present invention.</figref><figref num="11">[0020] FIG. 6 is a perspective view of a replaceable optical element according to an embodiment of the present invention.</figref><figref num="12">[0020] FIG. 6 is a plan view of an interchangeable optical element according to an embodiment of the present invention.</figref><figref num="13">[0021] FIG. 6 is a perspective view showing a buffer and an exchange mechanism for an interchangeable optical element according to an embodiment of the present invention.</figref><figref num="14">[0022] FIG. 6 is an enlarged view of a portion of the exchange mechanism of FIG. 13 showing the movement of the grip.</figref><figref num="15">[0022] Another enlarged view of a portion of the exchange mechanism of FIG. 13 showing the movement of the grip.</figref><figref num="16">It is a perspective view of an alternative storage and exchange mechanism according to a further embodiment of the present invention.</figref><figref num="17">[0024] FIG. 6 is a perspective view of an alternative storage and exchange mechanism according to a further embodiment of the present invention.</figref><figref num="18">[0025] FIG. 6 is a perspective view of an alternative slider configuration according to an embodiment of the present invention.</figref>