JP2005266146A - Optical element holding device, lens barrel, exposure device, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide; an optical element holding device and a lens barrel which allow assembling errors to be reduced to minimize aberrations and allow compatibility by holding to be enhanced; an exposure device improved in exposure precision; and a device manufacturing method of manufacturing devices having a high degree of integration, with a good yield. <P>SOLUTION: An optical element holding device 38 has: an annularly formed frame body 41 arranged in a peripheral edge of an optical element 37; and an annularly formed clamp member 42 arranged on an upper surface side of the optical element 37. The frame body 41 has a seat 44 for supporting a lower surface of the optical element 37. The clamp member 42 has an outer diameter made larger than that of the optical element 37, and also has a press part in a lower surface thereof. Since the press part and the seat 44 are in positions of the same phase, which are opposed to each other through the optical element 37 between them, the press part presses the optical element 37 to the seat 44 from the above to hold the optical element 37. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides an optical device for holding an optical element of an exposure apparatus used in a lithography process in a manufacturing process of a device such as a semiconductor element, a liquid crystal display element, an imaging element, a thin film magnetic head, or a mask such as a reticle or a photomask. The present invention relates to an element holding device. The present invention also relates to a lens barrel and an exposure apparatus provided with the optical element holding device. Furthermore, the present invention relates to a device manufacturing method using the exposure apparatus.

  In an exposure apparatus, a reticle such as a reticle or a photomask on which a predetermined pattern is formed is illuminated with predetermined exposure light, and an image of the predetermined pattern is coated with a photosensitive resin such as a photoresist via a projection optical system. Exposure is performed on a substrate such as a wafer or a glass plate (see Patent Document 1). In such an exposure apparatus, the wavelength of exposure light has been shortened to cope with the recent miniaturization of circuit patterns. Recently, far ultraviolet light, for example, KrF excimer laser (λ = 248 nm), vacuum ultraviolet ArF excimer laser (λ = 193 nm), F2 laser (λ = 157 nm) and the like have been developed. .

  By the way, as an optical element holding device in this type of exposure apparatus, for example, one having a structure as shown in FIGS. 8 and 9 is known. In this conventional configuration, a frame 202 for accommodating an optical element 201 such as an optical element is formed in an annular shape. On the inner peripheral surface of the frame 202, three narrow seating surfaces 204 for supporting the optical element 201 are formed at equal angular intervals. A screw hole 205 is formed on the upper surface of the frame 202 so as to correspond to the seating surfaces 204. Further, three clamp members 206 are attached to the upper surface of the frame body 202 at equal angular intervals by screwing bolts 207 into the respective screw holes 205.

These bolts 207 are tightened while adjusting the pressing force, and the outer peripheral flange portion 201a of the optical element 201 is sandwiched between the clamp members 206 and the seating surface 204 with a predetermined pressing force. As a result, the optical element 201 is held at a predetermined position in the frame body 202.
JP2003-307660

  In an exposure process using an exposure apparatus including such an optical element holding device, a photosensitive resin (for example, a novolak resin) is generally used as a resist layer applied on the wafer. For this reason, at the time of projection exposure, volatile substances generated from the photosensitive resin may adhere to the surface of the optical element located closest to the wafer in the projection optical system and contaminate the surface of the optical element. The contamination on the surface of the optical element changes the optical characteristics of the projection optical system and may cause exposure failure. Therefore, the optical element is removed from the lens barrel and the optical element is cleaned or replaced.

  However, in the conventional method of clamping with three members, the three members are independent of each other, and it is impossible to strictly align physical characteristics such as the spring constant of these clamp members, resulting in individual differences. It was. Further, it has been difficult to ensure position reproducibility. This optical element is usually a parallel plate or a lens with a very small curvature, and displacement in the direction perpendicular to the optical axis has little effect on the optical performance, so it is not constrained in this direction and is parallel to the optical axis. Restrain only in direction. Therefore, even if a mounting error in the direction perpendicular to the optical axis (horizontal direction in FIG. 9) is allowed, the optical element is inclined obliquely in the direction parallel to the optical axis (vertical direction in FIG. 9). It is necessary to hold it moderately so as not to be distorted. However, due to the large number of parts, there has been a problem that the optical characteristics of the optical element at the time of assembly do not match with the selected clamp member. For this reason, aberration occurs in the optical element, and formation of a highly accurate mask pattern has been hindered. Furthermore, since the position reproducibility by assembling is not ensured, the assembling work is complicated and takes time, and there is also a problem that the assembling productivity is impaired.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the present invention is to provide an optical element holding device and a lens barrel that can reduce the assembly error and minimize the aberration of the optical element in the exposure apparatus, and can improve the compatibility by holding. Another object of the present invention is to provide an exposure apparatus capable of improving exposure accuracy. A further object of the present invention is to provide a device manufacturing method capable of producing a highly integrated device with a high yield.

  In order to achieve the above object, an optical element holding device according to claim 1 is disposed on a frame, a seat provided on an inner periphery of the frame and supporting a lower surface of the optical element, and an upper surface side of the optical element. And an annular clamp member having an outer diameter larger than the outer diameter of the optical element, and the clamp member includes a pressing portion that presses the optical element against the seat. And

  Therefore, in the optical element holding device according to the first aspect, by providing an annular clamp member that includes a pressing portion that presses the optical element against the seat, the spring constant or the like is compared with the case where a plurality of clamp members are used. The error due to the individual difference in the physical characteristics is eliminated, the assembly error is further reduced, and stable optical characteristics can be obtained. In addition, it is possible to improve the hold compatibility at each replacement of the optical element. Further, the work by assembling is simplified, and the assembling productivity can be improved.

An optical element holding device according to a second aspect is the optical element holding device according to the first aspect, wherein the pressing portion presses the optical element in a direction parallel to the optical axis.
Therefore, in the optical element holding device according to claim 2, since the pressing portion presses the optical element straight in a direction parallel to the optical axis, the flatness is less likely to be lost, and the distortion and deformation of the optical element can be reduced. There is an effect that the imaging performance of the optical element can be maintained without deteriorating.

  The optical element holding device according to claim 3 is the configuration of the optical element holding device according to claim 1 or 2, wherein the seat has a protrusion that contacts a lower surface of the optical element, and the pressing portion is Protruding portions that contact the upper surface of the optical element, three seats are provided at equal angular intervals on the inner periphery of the frame body, and the pressing portion is connected to the seat via the optical element. The gist is that the optical elements are respectively held at opposite positions of the same phase and held between the seat and the pressing portion.

  Therefore, in the optical element holding device according to the third aspect, the three seats provided at equiangular intervals on the inner periphery of the frame, and the three seats and the relative direction in the direction parallel to the optical axis of the projection optical system. The optical element can be held so as to be sandwiched between the three pressing portions provided at the same phase position. Moreover, there is an effect that it can be held more stably by holding the three equiangular intervals.

  An optical element holding device according to a fourth aspect of the present invention is the optical element holding device according to any one of the first to third aspects, wherein the clamp member has a radius approximately from an inner peripheral edge of the clamp member. It has a leaf spring portion formed in a portion sandwiched between a pair of slits cut toward the outside in the direction, and the pressing portion is provided in the leaf spring portion, and when holding the optical element, The gist is that the pressing portion presses the optical element in a direction parallel to the optical axis by an urging force of the leaf spring portion in a direction parallel to the optical axis.

  Therefore, in the optical element holding device according to the fourth aspect, the leaf spring portion can be easily configured by the pair of slits, and the urging force by the leaf spring portion is utilized by providing the leaf spring portion with a pressing portion. Thus, the optical element can be pressed by the pressing portion.

  The optical element holding device according to claim 5 is the configuration of the optical element holding device according to claim 4, wherein the clamp member and the frame are fixed at a portion different from the leaf spring portion. The gist.

  Therefore, in the optical element holding device according to claim 5, in order to fix the clamp member and the frame body, the plate spring portion is not fixed directly, but is fixed at a portion different from the plate spring portion. The influence of fixing to the pressing part formed in the part can be reduced. For example, even if there is a difference in tightening and fixing force such as a bolt or a positional difference, the difference is not directly applied to the leaf spring part, so that the pressing force at each pressing part can be prevented from changing. effective.

  The optical element holding device according to claim 6 is the configuration of the optical element holding device according to claim 4 or 5, wherein the leaf spring portion is slightly smaller than a portion different from the leaf spring portion of the clamp member. The gist of the invention is to hold the optical element at a position warped in a direction away from the optical element.

  Therefore, in the optical element holding device according to the sixth aspect, since the urging force always acts on the leaf spring portion in the direction approaching the optical element, the optical element is pressed by the pressing portion formed on the leaf spring portion. And can be held.

  An optical element holding device according to a seventh aspect is the optical element holding device according to any one of the first to sixth aspects, wherein the clamp member and the frame body are respectively in corresponding positions. The gist is that a hole for positioning is provided.

  Therefore, in the optical element holding device according to the seventh aspect, by providing a positioning hole when holding the optical element, whether or not the rotational phase of the clamp member with respect to the frame is correct is inserted. It can be confirmed, and the phase can be easily assembled correctly in the fixing operation between the clamp member and the frame, and the assembly productivity can be improved.

  The optical element holding device according to claim 8 is the configuration of the optical element holding device according to any one of claims 1 to 7, wherein the clamp member is interposed between the clamp member and the frame body. The gist is that a distance adjusting member for adjusting the distance between the frame and the frame is provided.

  Therefore, in the optical element holding device according to the eighth aspect, for example, the distance between the clamp member and the frame body can be adjusted as desired by a distance adjusting member such as a washer, and the pressure at each pressing portion can be made uniform. effective.

  The optical element holding device according to claim 9 is the configuration of the optical element holding device according to any one of claims 1 to 8, wherein the optical element is a pattern formed on a mask in the projection exposure apparatus. The gist of the present invention is that it is one of a plurality of optical elements constituting a projection optical system for projecting the image on the substrate.

Therefore, in the optical element holding device according to the ninth aspect, there is an effect that an error when assembling the optical element as a projection optical system can be reduced and aberration can be minimized.
An optical element holding apparatus according to a tenth aspect is the optical element holding apparatus according to the ninth aspect, wherein the optical element is an optical element closest to the substrate of a projection optical system in the projection exposure apparatus. And

  Therefore, in the optical element holding device according to the tenth aspect, among the optical elements in the projection optical system, the optical element located closest to the wafer is easily contaminated by a volatile substance generated from the photosensitive resin applied on the wafer. On the other hand, there is an effect that the assembling error can be reduced and the aberration can be minimized.

  A lens barrel according to an eleventh aspect of the present invention is a lens barrel configured to include at least one optical element holding device, and includes the optical element holding device according to any one of claims 1 to 10. The gist.

Therefore, the lens barrel according to the eleventh aspect has an effect that the aberration can be reduced and the lens barrel can have a high compatibility of the optical element by the hold.
An exposure apparatus according to a twelfth aspect of the invention is an exposure apparatus that exposes an image of a predetermined pattern formed on a mask on a substrate under exposure light, and the image of the predetermined pattern according to claim 11. The gist is to transfer onto the substrate via a projection optical system in the lens barrel.

  Therefore, the exposure apparatus according to the twelfth aspect has an effect that an exposure apparatus with stable optical characteristics can be obtained by reducing the assembly error of the optical elements and minimizing the aberration.

  A device manufacturing method according to a thirteenth aspect is characterized in that, in the device manufacturing method including a lithography step, the exposure is performed using the exposure apparatus according to the twelfth aspect in the lithography step.

  Therefore, the device manufacturing method according to the thirteenth aspect has an effect that a high-quality device can be manufactured with a high yield by using an exposure apparatus that reduces the assembly error and minimizes the aberration.

Next, the technical ideas further included in the invention described in the above claims will be described below together with their actions.
(A) The optical element holding device according to any one of claims 1 to 10, wherein the outer shape of the pressing portion is substantially hemispherical.

  Therefore, in the optical element holding device according to (a), since the tip of the substantially hemispherical pressing portion is a part in contact with the optical element, the contact area can be made to be a minute contact area substantially equivalent to the point contact, There is an effect that stress due to a change in the angle of the pressing portion does not occur, and the imaging performance of the optical element can be prevented from deteriorating due to deformation of the optical element.

(B) The optical element holding device according to claim 7, wherein two pin holes for positioning are provided in each of the clamp member and the frame body.
Therefore, in the optical element holding device according to (a), if the pin is inserted into the positioning hole when holding the optical element, the clamp member rotates relative to the central axis (optical axis AX) of the clamp member. Positioning in the direction and the vertical direction will be performed. Therefore, there is an effect that position reproducibility is ensured, and fixing work by a bolt or the like between the clamp member and the frame can be facilitated.

(C) The optical element holding device according to any one of claims 1 to 10, or (a) or (b), wherein the clamp member is integrally formed.
Accordingly, since the respective pressing portions included in the clamp member are formed of the same material, the contained components, the crystal structure due to quenching, and the like are the same, the spring constant is made uniform, and the optical element can be held in a well-balanced manner. Further, even when the clamp members are replaced, the clamp members are formed of the same material, and therefore can be replaced with simple work without adjusting the respective pressing portions. Therefore, the compatibility of the clamp member can be improved.

  As described above in detail, according to the present invention, an optical element holding device and a lens barrel that can reduce the assembly error and minimize the aberration and can improve the compatibility by the holding, in the optical element in the exposure apparatus. Can be provided. In addition, an exposure apparatus with high exposure accuracy can be provided. Furthermore, it is possible to provide a device manufacturing method capable of producing a highly integrated device with a high yield.

  Hereinafter, the exposure apparatus, the barrel, and the optical element holding apparatus of the present invention hold the exposure apparatus for manufacturing a semiconductor element and the barrel that houses the projection optical system, and the optical element closest to the photosensitive substrate of the projection optical system. An embodiment embodied in an optical element holding device will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of the exposure apparatus 31 with the projection optical system 35 as the center. As shown in FIG. 1, an exposure apparatus 31 of this embodiment includes a light source 32, an illumination optical system 33, a reticle stage 34 that holds a reticle Rt as a mask, a projection optical system 35, and a wafer W as a substrate. And a wafer stage 36 for holding the wafer.

In this embodiment, the light source 32 oscillates an F ₂ laser having a wavelength of 157 nm. In addition, a KrF excimer laser with a wavelength of 248 nm, an ArF excimer laser with a wavelength of 193 nm, or the like can also be used.

  The illumination optical system 33 includes an optical integrator (not shown) such as a fly-eye lens and a rod lens, various lens systems such as a relay lens and a condenser lens, an aperture stop, and the like. The exposure light EL emitted from the light source 32 is adjusted so as to uniformly illuminate the pattern on the reticle Rt by passing through the illumination optical system 33.

  In the reticle stage 34, on the exit side of the illumination optical system 33, that is, on the object plane side (incident side of the exposure light EL) of the projection optical system 35 described later, the mounting surface of the reticle Rt is the optical axis of the projection optical system 35. They are arranged so as to be substantially orthogonal to the AX direction.

  The projection optical system 35 includes a plurality of optical elements 37 such as lenses. In the projection optical system 35, an optical element 37 is accommodated in a lens barrel 39 formed by stacking a plurality of lens barrel modules 39a so that the optical axes AX coincide with each other. Each of the plurality of lens barrel modules 39 a holds one or more optical elements 37.

  Among the plurality of lens barrel modules 39a, a specific lens barrel module 39a holds the optical element 37 via the optical element holding device 38 (see FIG. 2) of the present invention. Note that the other lens barrel module 39a may also be held via the optical element holding device of the present invention, or may be held by an optical element holding device configured by another mechanism. In the present embodiment, the optical element 37 is the optical element closest to the substrate (wafer W) in the projection optical system 35, and is a parallel plate or an almost parallel plate optical element with almost no curvature. It is said. In the case of a parallel plate, an optical axis does not exist in a strict sense, but for the sake of convenience, description will be made assuming that the central axis of the optical element is the optical axis.

  The wafer stage 36 is disposed on the image plane side of the projection optical system 35 (exposing side of the exposure light EL) so that the mounting surface of the wafer W intersects the optical axis direction of the projection optical system 35. Then, the image of the pattern on the reticle Rt illuminated with the exposure light EL is projected and transferred onto the wafer W on the wafer stage 36 in a state of being reduced to a predetermined reduction magnification through the projection optical system 35. ing.

  Next, the detailed configuration of the optical element holding device 38 will be described. 2 is an exploded perspective view showing the optical element holding device 38, FIG. 3 is a plan view showing the optical element holding device 38, and FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. Further, FIG. 5 is a view of a part of the clamp member as viewed from the lower side (lower side in FIG. 2).

  As shown in FIG. 2, the optical element holding device 38 is arranged on the upper surface side of the optical element 37 and the frame body 41 formed in an annular shape arranged on the periphery of the optical element 37, and the outer diameter thereof is the optical element. And an annular clamp member 42 formed larger than the outer diameter of 37. The optical element 37 is clamped to the frame body 41 by the clamp member 42 and is held between the clamp member 42 and the frame body 41.

  The frame body 41 is formed with a receiving portion 43 in the form of a flange on the inner periphery of the frame body 41, and three seats 44 project from the upper surface of the receiving portion 43 at regular angular intervals as protrusions. ing. The seat 44 is constituted by a minute plane seat that contacts the lower surface of the optical element 37 with a minute area. The three seats 44 support the lower surface of the optical element 37. In addition, a plurality of screw holes 45 (in the present embodiment, a pair of screw holes 45, three pairs in total of six pairs at equal angular intervals) are formed near the inner peripheral edge of the upper surface of the frame body 41. Yes. Bolts 46 for fixing the clamp member 42 and the frame body 41 are inserted into the screw holes 45. Furthermore, two pin holes 47 for positioning when fixing the clamp member 42 to the frame body 41 are formed in the vicinity of the inner peripheral edge of the upper surface of the frame body 41 at 180 ° symmetrical positions (note that Only one appears in the drawing of FIG. 2).

  On the other hand, the clamp member 42 is formed of an elastic member such as steel. The clamp member 42 is formed with a pair of slits (desirably parallel to each other) from the inner peripheral edge to the outside in the radial direction, and is sandwiched between the pair of slits. A leaf spring portion 49 is formed by the portion. Three pairs of slits are formed on the clamp member 42 at equiangular intervals, whereby three leaf spring portions 49 are formed at equiangular intervals. Furthermore, a pressing portion 50 that presses the vicinity of the periphery of the upper surface of the optical element 37 is provided on the lower surfaces of the three leaf spring portions 49 (see FIG. 5). The pressing portion 50 is formed as a protruding portion that protrudes from the leaf spring portion 49, and the outer shape thereof is substantially hemispherical. Further, the three pressing portions 50 are formed at positions facing the three seats formed on the upper surface of the receiving portion 43 of the frame body 41 with the optical element 37 interposed therebetween. The pressing portion 50 is a protruding portion obtained by pressing from the upper surface side of the clamp member 42 with a bar-shaped member having a thin tip, and the protruding height is made uniform by grinding the protruding portion after pressing. Aligned and formed.

  Further, the clamp member 42 has a plurality of screw holes (however, the diameter of the screw holes 51 is larger than that of the bolt 46 and is commonly referred to as an idiot hole) 51 (in this embodiment, the pair of screw holes 51 are spaced at equal angular intervals). A total of 6 pairs of 3 pairs). The screw hole 51 is formed at a position away from the leaf spring portion 49 to some extent and at a position corresponding to the screw hole 45 formed on the frame body 41 side. Further, two pin holes 52 for positioning when fixing the clamp member 42 to the frame body 41 are formed at positions corresponding to the pin holes 47 formed on the frame body 41 side, at 180 ° symmetrical positions. .

  In addition, washers 53 for adjusting the distance between the clamp member 42 and the frame body 41 as desired are provided at portions (6 places in the present embodiment) where the clamp member 42 and the frame body 41 are fixed by the bolts 46. It has been.

  Further, a marking line 54 for positioning when holding the optical element 37 on the frame body 41 is formed on the side surface of the optical element 37, and similarly, a marking line 55 is formed on the upper surface of the frame body 41. The markings 54 and 55 are adjusted by visual observation so that they can be aligned, and the optical element 37 can be positioned in the rotational direction with respect to the center axis (the optical axis AX of the projection optical system 35). Then, with the optical element 37 placed on the three seats 44 of the frame body 41, the bolts 46 are screwed into the screw holes 45 of the frame body 41 via the screw holes 51 of the clamp member 42, thereby clamping The member 42 is fixed to the frame body 41.

  When the clamp member 42 is fixed to the frame body 41, the three leaf spring portions 49 of the clamp member 42 are elastically deformed slightly upward with respect to a portion different from the leaf spring portion 49 of the clamp member 42. Since the leaf spring portion 49 is formed integrally with the clamp member 42, the upward force due to this elastic deformation is a force that opposes a portion different from the leaf spring portion 49 of the clamp member 42. Therefore, a downward biasing force always acts on the leaf spring portion 49 due to the generation of this force, and this biasing force becomes a pressing force for pressing the optical element 37 against the three seats 44 of the frame body 41. .

  As shown in FIG. 4, when the optical element 37 is held between the clamp member 42 and the frame body 41, the lower surface of the optical element 37 is placed on the receiving portion 43 of the frame body 41 as described above. It is supported by the three seats 44 formed. On the other hand, the three leaf spring portions 49 of the clamp member 42 hold the optical element 37 at a position slightly above the portion different from the leaf spring portion 49 of the clamp member 42 (in a direction away from the optical element 37). doing. The leaf spring portion 49 extending slightly upward is always urged parallel to the optical axis AX and downward (on the optical element 37 side), so that the pressing portion 50 formed on the lower surface of the leaf spring portion 49. (See FIG. 5) presses the optical element 37 in a direction parallel to the optical axis AX. Here, the three pressing portions 50 are in-phase positions facing the three seats 44 of the frame body 41 via the optical element 37 (positions facing in a direction parallel to the optical axis AX of the projection optical system 35). Is provided. Therefore, the lower surface of the optical element 37 is supported by the three seats 44 and is pressed by the pressing portion 50 at the position of the upper surface in the same phase corresponding to the position supported by the seat 44. That is, it is held so as to be sandwiched between the three sets of seats 44 and the pressing portion 50. This is for minimizing the deformation of the optical element 37 by pressing the optical element 37 configured in a substantially parallel plate perpendicularly to the plane with the projections of the pressing part 50 in phase with the seat. . The reason why the protrusions of the pressing part 50 are formed in a hemispherical shape is that no stress is applied to the optical element 37. This is to prevent the imaging performance of the optical element 37 from deteriorating.

Next, a procedure for holding the optical element 37 using the optical element holding device 38 described above will be described.
First, the optical element 37 is placed on the receiving portion 43 of the frame body 41 so that the positions of the marking line 54 formed on the side surface of the optical element 37 and the marking line 55 formed on the upper surface of the frame body 41 are aligned. To do. At this time, the lower surface of the optical element 37 is supported by three seats 44 formed on the upper surface of the receiving portion 43. Next, the clamp member 42 is fixed to the frame body 41 with a bolt 46 via a washer 53 between the clamp member 42 and the frame body 41. At this time, the central axis (optical axis AX) of the clamp member 42 and the frame body 41 is coaxial, and the pin holes 47 and 52 formed in the respective positions are at the same position. A pin is inserted into 52. The clamp member 42 is positioned in the rotational direction and the vertical direction with respect to the central axis (optical axis AX) of the clamp member 42 by being fixed by the pins at two locations. Therefore, the fixing work of the clamp member 42 and the frame body 41 by the bolt 46 can be facilitated, and the assembly productivity can be improved.

  The optical element holding device 38 configured as described above, the lens barrel module 39a including the optical element holding device 38, and the exposure apparatus 31 shown in FIG. 1 using the lens barrel 39 configured thereby are manufactured as follows, for example. The

  First, the optical element 37 on the most substrate (wafer W) side constituting the projection optical system 35 is held by the optical element holding device 38 of the above-described embodiment, and this projection optical system 35 is incorporated in the main body of the exposure apparatus 31 to perform optical adjustment. I do.

Next, a wafer stage 36 (including a reticle stage 34 in the case of a scan type exposure apparatus) made up of a large number of mechanical parts is attached to the main body of the exposure apparatus 31 to connect wiring. After the gas supply pipe for supplying gas is connected to the optical path of the exposure light, the inside of the lens barrel is purged. In this case, N ₂ is filled after thoroughly removing O ₂ and moisture in the lens barrel. Furthermore, comprehensive adjustment (electric adjustment, operation check, etc.) is performed.

  Here, each component constituting the optical element holding device 38 and a sealing member such as an O-ring are processed by ultrasonic cleaning or the like to remove impurities such as processing oil and metal substances so that they do not become an outgas emission source. Done and assembled. The exposure apparatus 31 is preferably manufactured in a clean room in which the temperature, humidity, and pressure are controlled and the cleanness is adjusted.

Next, an embodiment of a device manufacturing method using the exposure apparatus 31 described above in a lithography process will be described.
FIG. 6 is a flowchart showing a manufacturing example of a device (a semiconductor element such as an IC or LSI, a liquid crystal display element, an imaging element (CCD or the like), a thin film magnetic head, a micromachine, or the like). As shown in FIG. 6, first, in step S101 (design step), function / performance design (for example, circuit design of a semiconductor device) of a device (microdevice) is performed, and pattern design for realizing the function is performed. Do. Subsequently, in step S102 (mask manufacturing step), a mask (such as a reticle Rt) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S103 (substrate manufacturing step), a substrate (wafer W when silicon material is used) is manufactured using a material such as silicon or glass plate.

  Next, in step S104 (substrate processing step), using the mask and substrate prepared in steps S101 to S103, an actual circuit or the like is formed on the substrate by lithography or the like, as will be described later. Next, in step S105 (device assembly step), device assembly is performed using the substrate processed in step S104. Step S105 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation or the like) as necessary.

  Finally, in step S106 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S105 are performed. After these steps, the device is completed and shipped.

  FIG. 7 is a diagram showing an example of a detailed flow of step S104 of FIG. 6 in the case of a semiconductor device. In FIG. 7, in step S111 (oxidation step), the surface of the wafer W is oxidized. In step S112 (CVD step), an insulating film is formed on the surface of the wafer W. In step S113 (electrode formation step), an electrode is formed on the wafer W by vapor deposition. In step S114 (ion implantation step), ions are implanted into the wafer W. Each of the above steps S111 to S114 constitutes a pretreatment process at each stage of the wafer processing, and is selected and executed according to a necessary process at each stage.

  At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing process, first, a photosensitive agent is applied to the wafer W in step S115 (resist formation step). Subsequently, in step S116 (exposure step), the circuit pattern of the mask (reticle Rt) is transferred onto the wafer W by the lithography system (exposure apparatus 31) described above. Next, in step S117 (developing step), the exposed wafer W is developed, and in step S118 (etching step), the exposed members other than the portion where the resist remains are removed by etching. In step S119 (resist removal step), the resist that has become unnecessary after the etching is removed.

Multiple circuit patterns are formed on the wafer W by repeatedly performing these pre-processing and post-processing steps.
By using the device manufacturing method of the embodiment described above, the exposure process the exposure device 31 (Step S116) is used, it is possible to improve the resolution by the exposure light EL of the F ₂ laser, moreover exposure control It can be performed with high accuracy. Therefore, as a result, a highly integrated device having a minimum line width of 0.1 μm can be produced with high yield.

In the above embodiment, the following effects can be obtained.
(1) Since the outer diameter of the clamp member 42 is larger than the outer diameter of the optical element 37 and is a single member formed integrally, the spring constant at the holding portion by the three pressing portions 50, etc. The deformation error due to the difference in the physical characteristics of the optical element 37 is small, and since this error is small, the imaging performance of the optical element 37 is hardly shifted.

(2) Since the number of assembling steps is reduced by reducing the number of parts, the assembling work of the projection optical system 35 is facilitated, and the productivity can be improved.
(3) The leaf spring portion 49 is formed by a pair of slits cut from the inner peripheral edge of the clamp member 42 generally outward in the radial direction. Further, the leaf spring portion 49 is a plate spring that can be biased with a predetermined pressing force by being positioned slightly along the direction away from the optical element 37 from a portion different from the leaf spring portion 49 of the clamp member 42. There is an effect that the function can be realized.

  (4) Further, since the pressing portion 50 as a hemispherical protrusion is formed on the lower surface of the leaf spring portion 49, the leaf spring portion 49 is biased downward in parallel with the optical axis AX. Accordingly, there is an effect that the pressing portion 50 can press the optical element 37 from above to hold the optical element 37 without stress.

  (5) The clamp member 42 and the frame 41 have two pin holes 47 and 52 at corresponding positions, respectively. For this reason, the clamp member 42 can be fixed to the frame body 41 with the pins inserted into the pin holes 47 and 52. That is, the clamp member 42 has an effect that the position reproducibility in the rotation direction and the vertical direction with respect to the central axis of the clamp member 42 is ensured, and the optical element 37 can be exchanged more efficiently.

  (6) By providing the washer 53 between the clamp member 42 and the frame body 41, the distance between the clamp member 42 and the frame body 41 can be adjusted, and the balance of the pressing force by the pressing portion 50 can be adjusted. effective.

  (7) Since the fixing position of the clamp member 42 and the frame 41 by the bolt 46 is not on the leaf spring portion 49 but at a certain distance from the leaf spring portion 49, the biasing force (pressing force of the leaf spring portion 49) There is an effect that the influence on the pressing force by the portion 50) and the spring constant can be reduced.

  (8) The optical element 37 is the optical element closest to the substrate (wafer W) among the optical elements constituting the projection optical system 35. This optical element is a parallel plate or an almost parallel plate optical element with almost no curvature, and the displacement in the direction perpendicular to the optical axis AX hardly affects the optical performance. Therefore, it is not restricted in the direction perpendicular to the optical axis AX, and is restricted only in the direction parallel to the optical axis AX. In the above embodiment, since the pressing portion 50 (see FIG. 5) formed on the lower surface of the leaf spring portion 49 presses the optical element 37 in a direction parallel to the optical axis AX, the optical element 37 is parallel to the optical axis AX. There is an effect that it can be held so as not to be inclined or distorted with respect to the direction.

In addition, you may change the said embodiment as follows.
The fixing position of the clamp member 42 and the frame body 41 by the bolt 46 is set to a position away from the leaf spring portion 49 to some extent, but it may be fixed at the portion of the leaf spring portion 49 instead. In this case, for example, if the vicinity of the outer peripheral edge of the clamp member 42 is fixed between a pair of slits, the spring constant of the leaf spring portion 49 and the pressing force of the pressing portion 50 formed near the inner peripheral edge are affected. Therefore, the number of members such as the bolts 46 can be reduced and fixed.

The leaf spring portion 49 is configured as a portion sandwiched between a pair of slits, but may instead be configured to protrude toward the center at three locations inside the annular clamp member 42.
○ Two pin holes 47 and 52 for positioning when fixing the clamp member 42 to the frame body 41 are provided at 180 ° symmetrical positions, but the positions and the number thereof are not limited at all. . Thus, for example, three or a plurality of three or more may be provided.

  In the present embodiment, the optical element holding device 38 has been described by taking the optical element closest to the substrate among the projection optical systems 35 as an example, but may be applied to other optical elements of the projection optical system 35. . Further, the present invention can be applied not only to the projection optical system 35 but also to optical elements (reflecting mirrors, lenses, etc.) constituting the illumination optical system. Furthermore, the optical element held by the optical element holding device 38 is not limited to a parallel plate optical element, and can be applied to a lens having a curvature, for example, a concave lens or a convex lens.

  ○ As an exposure device, without using a projection optical system, a contact exposure device that exposes the mask pattern by bringing the mask and substrate into close contact, and a proximity exposure device that exposes the mask pattern by bringing the mask and substrate close together It can also be applied to an optical system. Further, the projection optical system is not limited to the total refraction type, but may be a catadioptric type.

Further, the exposure apparatus of the present invention is not limited to a reduction exposure type exposure apparatus, and may be, for example, an equal exposure type exposure apparatus or an enlargement exposure type exposure apparatus.
○ Also, from a reticle to a glass substrate, not only for microdevices such as semiconductor elements, but also for manufacturing reticles or masks used in light exposure equipment, EUV exposure equipment, X-ray exposure equipment, electron beam exposure equipment, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a silicon wafer or the like. Here, in an exposure apparatus using DUV (deep ultraviolet) or VUV (vacuum ultraviolet) light, a transmission type reticle is generally used. As a reticle substrate, quartz glass, quartz glass doped with fluorine, fluorite, fluoride, and the like are used. Magnesium or quartz is used. In proximity type X-ray exposure apparatuses and electron beam exposure apparatuses, a transmission type mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate.

  Further, the exposure apparatus may be an exposure apparatus that uses an immersion method in order to ensure a wide depth of focus. In this immersion method, a space between the lower surface of the projection optical system and the substrate surface is filled with a predetermined liquid (such as water or an organic solvent) to form an immersion region, and the wavelength of exposure light in the liquid is air. The resolution is improved by utilizing 1 / n (n is the refractive index of the liquid, usually about 1.2 to 1.6), and the depth of focus is expanded about n times.

  Of course, the present invention is applied not only to an exposure apparatus used for manufacturing a semiconductor element but also to an exposure apparatus used for manufacturing a display including a liquid crystal display element (LCD) to transfer a device pattern onto a glass plate. can do. The present invention can also be applied to an exposure apparatus used for manufacturing a thin film magnetic head or the like and transferring a device pattern onto a ceramic wafer or the like, and an exposure apparatus used for manufacturing an image pickup device such as a CCD.

  Further, the present invention can be applied to a scanning stepper that transfers a mask pattern to a substrate while the mask and the substrate are relatively moved, and sequentially moves the substrate in steps. The present invention can also be applied to a step-and-repeat stepper in which the mask pattern is transferred to the substrate while the mask and the substrate are stationary, and the substrate is sequentially moved stepwise.

As a light source of the exposure apparatus, in addition to the F ₂ laser (157 nm) described in the above embodiment, ArF excimer laser (193 nm), for example, g-line (436 nm), i-line (365 nm), KrF excimer laser (248 nm) ), Kr ₂ laser (146 nm), Ar ₂ laser (126 nm), or the like may be used. In addition, a single wavelength laser beam in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear optical crystal is obtained. It is also possible to use harmonics that have been converted into ultraviolet light.

1 is a schematic block diagram showing an embodiment of an exposure apparatus of the present invention. The disassembled perspective view which shows the optical element holding | maintenance apparatus of FIG. The top view which shows the optical element holding | maintenance apparatus of FIG. FIG. 4 is a sectional view taken along line 4-4 of FIG. The figure which looked at a part of clamp member from the lower side. The figure which shows the flowchart of the manufacture example of devices (semiconductor elements, such as IC and LSI, a liquid crystal display element, an image pick-up element (CCD etc.), a thin film magnetic head, a micromachine, etc.). The figure which shows an example of the detailed flow of step S104 of FIG. 6 in the case of a semiconductor device. The disassembled perspective view which shows the optical element holding | maintenance apparatus of a conventional structure. Sectional drawing of the optical element holding | maintenance apparatus of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 31 ... Exposure apparatus (projection exposure apparatus), 35 ... Projection optical system, 37 ... Optical element, 38 ... Optical element holding apparatus, 39 ... Lens barrel, 41 ... Frame, 42 ... Clamp member, 44 ... Seat (projection part) , 47: Pin hole (positioning hole), 49: Leaf spring part, 50: Pressing part (projection part), 52 ... Pin hole (positioning hole), 53 ... Washer (space adjusting member), AX ... Light Axis, Rt ... reticle as mask, W ... wafer as substrate.

Claims (13)

A frame, a seat provided on the inner periphery of the frame to support the lower surface of the optical element, and disposed on the upper surface side of the optical element, the outer diameter of which is larger than the outer diameter of the optical element An annular clamping member,
The said clamp member is provided with the press part which presses the said optical element with respect to the said seat, The optical element holding | maintenance apparatus characterized by the above-mentioned. The optical element holding device according to claim 1, wherein the pressing unit presses the optical element in a direction parallel to the optical axis. The seat has a protrusion that contacts the lower surface of the optical element, and the pressing portion has a protrusion that contacts the upper surface of the optical element,
Three seats are provided at equiangular intervals on the inner periphery of the frame, and the pressing portions are provided at the same phase positions facing the seat via the optical element, respectively.
The optical element holding device according to claim 1, wherein the optical element is held between the seat and the pressing portion. The clamp member has a leaf spring portion formed at a portion sandwiched between a pair of slits cut from the inner peripheral edge of the clamp member generally outward in the radial direction, and the pressing portion is the leaf spring portion. It is provided in
When holding the optical element, the pressing portion presses the optical element in a direction parallel to the optical axis by an urging force of the leaf spring portion in a direction parallel to the optical axis. The optical element holding device according to any one of claims 1 to 3. The optical element holding device according to claim 4, wherein the clamp member and the frame are fixed at a portion different from the leaf spring portion. The said leaf | plate spring part hold | maintains the said optical element in the position slightly curved in the direction spaced apart from an optical element rather than the part different from the said leaf | plate spring part of the said clamp member. 5. The optical element holding device according to 5. The optical element holding device according to any one of claims 1 to 6, wherein positioning holes are provided at corresponding positions in the clamp member and the frame body, respectively. The space | interval adjustment member which adjusts the space | interval of the said clamp member and the said frame is provided between the said clamp member and the said frame, The any one of Claim 1 thru | or 7 characterized by the above-mentioned. The optical element holding device according to Item. 2. The optical element according to claim 1, wherein the optical element is one of a plurality of optical elements constituting a projection optical system that projects an image of a pattern formed on a mask on a substrate in a projection exposure apparatus. 9. The optical element holding device according to any one of 8 above. The optical element holding device according to claim 9, wherein the optical element is an optical element closest to the substrate of a projection optical system in the projection exposure apparatus. A lens barrel comprising at least one optical element holding device, wherein the lens barrel comprises the optical element holding device according to any one of claims 1 to 10. 12. An exposure apparatus that exposes an image of a predetermined pattern formed on a mask on a substrate under exposure light, the image of the predetermined pattern via a projection optical system in a lens barrel according to claim 11. An exposure apparatus for transferring onto the substrate. A device manufacturing method including a lithography process, wherein exposure is performed using the exposure apparatus according to claim 12 in the lithography process.

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