JP5168507B2 - Optical element holding mechanism, optical system barrel, and exposure apparatus - Google Patents

Description

  The present invention relates to a mechanism for holding an optical element such as a lens or a mirror in an optical system barrel. In particular, the present invention relates to an optical element holding mechanism that can suppress deformation of an optical element in a precision optical machine such as a semiconductor device exposure apparatus. The present invention also relates to an exposure apparatus having such an optical element holding mechanism.

  The background art will be described by taking an EUV light (extreme ultraviolet light) exposure apparatus as an example.

  FIG. 13 is a diagram showing a schematic configuration example of an EUV light exposure apparatus.

  The exposure apparatus shown in FIG. 13 includes an EUV source 101, an illumination optical system 103 that irradiates the reflective mask 102 with EUV light (wavelength 13.4 nm) 100 emitted from the EUV source 101, and a circuit on the reflective mask 102. It comprises an EUV projection optical system 105 that projects a pattern onto a wafer 104, a mask stage 106, and a wafer stage 107.

  In this exposure apparatus, the EUV light 100 emitted from the EUV source 101 is applied to the reflective mask 102 via the illumination optical system 103. The EUV light 100 reflected by the reflective mask 102 enters the projection optical system 105. The EUV light 100 that has passed through the projection optical system 105 reaches the wafer 104, and the pattern on the reflective mask 102 is reduced and transferred onto the wafer 104.

  The projection optical system 105 is composed of, for example, six multilayer mirrors (not shown), and its reduction magnification is 1/5. The projection optical system 105 has a ring-shaped exposure field having a width of 2 mm and a length of 30 mm on the wafer 104. Each reflecting mirror has an aspheric reflecting surface, and the surface thereof is coated with a Mo / Si multilayer film for improving the reflectance of EUV light. At the time of exposure, the reflective mask 102 and the wafer 104 are scanned on the stages 106 and 107, respectively. The scanning speed of the wafer 104 is always synchronized so as to be 1/5 of the scanning speed of the reflective mask 102. As a result, a pattern extending over a region larger than the field of view of the optical system can be transferred.

  Next, the optical system barrel will be described in more detail with reference to FIG.

  FIG. 14 is a block diagram showing an example of an optical column of the EUV light exposure apparatus.

  FIG. 14 shows an optical system barrel 110 that holds two reflecting mirrors (optical elements) 111 and 112. The lens barrel 110 includes a lens barrel body 110a and a flange portion 110b. The lens barrel 110 is made of Invar and is not easily heat denatured.

  The reflecting mirror 111 is held by a holding mechanism 116 via a position adjusting mechanism (piezo motor or the like) 115 on the flange portion 110 b of the lens barrel 110. The position adjusting mechanism 115 is a mechanism for adjusting the position of the reflecting mirror at the time of assembly or after that. On the other hand, the reflecting mirror 112 is held by the holding mechanism 117 under the flange portion 110 b of the lens barrel 110. The two reflecting mirrors 111 and 112 have holes 111a and 112a, respectively. The light 100 emitted from the upper mask (object, not shown) in the figure passes through the hole 111 a of the upper reflecting mirror 111 and reaches the upper surface of the lower reflecting mirror 112, and the reflected light 100 is reflected by the reflecting mirror 111. Head to the bottom of the. The light 100 is further reflected by the lower surface of the reflecting mirror 111, travels downward, and reaches the wafer (image plane, not shown) through the hole 112a of the reflecting mirror 112.

  In the EUV optical system, the Mo / Si multilayer film is coated on the surface of the reflecting mirror (optical element) as described above. The numerical aperture of the EUV optical system is 0.3, and the wavefront aberration is required to be 1 nm RMS or less. In order to realize such a small wavefront aberration, it is necessary to use an aspherical mirror having a highly accurate shape as a reflecting mirror and to assemble and adjust the mirror with high accuracy.

As described with reference to FIG. 14, the optical element is held on the lens barrel 110 by the holding mechanisms 116 and 117. This type of holding mechanism preferably has a function of holding a highly accurate mirror without being deformed and a function of keeping the position of the optical element unchanged.
Here, as a function of preventing the optical element from being deformed, a function of suppressing the distortion (nonuniform deformation) of the optical element by deforming the holding mechanism when the optical element is thermally expanded is considered. On the other hand, as a function of preventing the position of the optical element from changing, it is conceivable to restrain the optical element in all directions. Furthermore, it is also necessary to prevent displacement due to slipping or the like when the lens barrel is vibrated.

  The present invention has been made in view of such problems, and can suppress deformation and position change of the optical element, or can positively deform the optical element to obtain better optical performance. An object of the present invention is to provide an optical element holding mechanism that can be used.

The optical element holding mechanism according to claim 1 is a mechanism for holding an optical element in an optical system barrel, and holding a holding member that holds an end of the optical element, and a diameter of the optical element. Direction, circumferential direction, and tilt direction are supported flexibly, and the first elastic support member is supported with high rigidity in the gravity direction, and the holding member is flexibly supported in the radial direction and gravity direction, and the circumferential direction is And a second elastic support member supported with high rigidity .

  According to this optical element holding mechanism, since the rigidity of the first elastic support member in the direction other than the gravitational direction is flexible, the strain generated when the holding mechanism and the optical element are coupled (the flatness of both contact surfaces is reduced). The resulting strain) can be absorbed by deformation of the elastic support member. Therefore, deformation of the optical element at the time of coupling can be suppressed. Furthermore, even when the end of the optical element moves in the radial direction due to a temperature change, the optical element holding mechanism can suppress deformation of the optical element.

  In the optical element holding mechanism according to claim 2, the first elastic support member and / or the second elastic support member are arranged in series in the direction of supporting with high rigidity, and each of them is easily bent in the flexible direction. It can consist of two sets of leaf springs.

  In this case, the supporting force of the elastic support member can be easily realized.

  In the optical element holding mechanism according to a third aspect, the two sets of leaf springs may be two-dimensional leaf springs built so as to be orthogonal to one block.

  In this case, as described above, two sets of leaf spring functions can be realized in a small space in one block.

  5. The optical element holding mechanism according to claim 4, wherein the centers of the two sets of leaf springs of the elastic support member coincide with the centers of the holding protrusions at the ends of the holding member and the optical element. Is preferred.

  A moment force acts on the optical element in addition to a simple pulling force. These external forces may adversely affect the shape of the optical element. In this aspect of the present invention, by aligning the leaf spring and the center of the holding projection, no excessive force is generated in the holding projection portion, so that the deformation of the optical element can be suppressed to a small level.

  In the optical element holding mechanism according to claim 5, three or more sets of the holding member, the first elastic support member, and the second elastic support member are dispersedly arranged on the side periphery of the optical element. Can be.

  In this case, the binding force of the optical element can be obtained in all horizontal directions.

  The optical system barrel according to claim 6 is an optical system barrel including an optical element holding mechanism, a position adjusting mechanism of the optical element and / or a shape adjusting mechanism of the optical element, The element holding mechanism is the optical element holding mechanism described above.

  The optical system barrel according to claim 7 is characterized in that the shape adjusting mechanism applies a moment to the optical element via the holding mechanism to correct a shape error of the optical element.

  By correcting the shape error of the optical element by the shape adjustment mechanism, desired wavefront aberration and resolution can be easily obtained.

  In the optical system barrel according to an eighth aspect, the shape adjusting mechanism may include an actuator that applies a horizontal displacement to the holding mechanism.

  In this case, the optical element can be deformed by applying displacement to the holding mechanism with the actuator. When the optical element is deformed, the wavefront aberration changes. Therefore, the desired wavefront aberration can be obtained by adjusting the shape of the optical element while referring to this change.

  The optical system barrel according to claim 9 is characterized in that the position adjustment mechanism includes an actuator and a drive amount reduction mechanism that reduces the movement of the actuator and transmits the reduced movement to the optical element holding mechanism.

  Such an optical system barrel is suitable when the required position accuracy is as small as about 1 μm because the optical element can be finely adjusted by the drive amount reduction mechanism.

  The exposure apparatus according to claim 10 is an exposure apparatus that selectively irradiates a sensitive substrate with an energy beam to form a pattern, and includes the above-described optical system barrel on which the optical system of the energy beam is mounted. It is characterized by.

  The type of the energy beam is not limited to EUV light, but may be ultraviolet light, electron beam, ion beam, or the like. Further, the exposure method is not particularly limited, and may be reduced projection exposure or equal magnification proximity transfer.

As apparent from the above description, according to the present invention, there is an effect that deformation of the optical element can be suppressed.

FIG. 1A is a plan view showing a mirror holding mechanism in the optical system barrel according to the first embodiment of the present invention, and FIG. 1B is an enlarged view of an adhesive member of the holding mechanism. FIG. 2A is a side sectional view showing the mirror holding mechanism, and FIG. 2B is a plan view of a bowl-shaped member of the mechanism. It is side surface sectional drawing which shows the optical system barrel of the exposure apparatus which concerns on 2nd Example of this invention. It is a plane sectional view showing a mirror in the barrel and its holding mechanism. It is a front view which shows the detailed structure of the holding member of the holding mechanism. 6A is a cross-sectional view taken along line XX in FIG. 5, FIG. 6B is an explanatory view showing a free state of the outer clamping member, and FIG. 6C is an adjustment of the outer clamping member. It is explanatory drawing which shows a back state. It is sectional drawing which follows the YY line | wire of FIG. It is sectional drawing which follows the ZZ line | wire of FIG. It is a figure which shows the detailed structure of the elastic support member (two-dimensional leaf | plate spring) of the holding mechanism shown in FIG.3 and FIG.4. (A) is a front view, (B) is a side view, (C) is a top view, and (D) is a bottom view. FIG. 10A is a plan view mainly showing an example of the drive amount reduction mechanism of the position adjustment mechanism (81 82) in the present embodiment, and FIG. 10B is an example of the position adjustment mechanism (80). It is a block diagram mainly shown. It is a figure which shows the example in which the two-dimensional actuator (shape adjustment mechanism) was provided between the two-dimensional leaf | plate spring and the ring. FIG. 12A is a plan view showing an example of the fixing mechanism of the optical barrel according to the present invention, and FIG. 12B is a side view of the fixing mechanism. It is a figure which shows the schematic structural example of an EUV light exposure apparatus. It is a block diagram which shows an example of the optical system barrel of an EUV light exposure apparatus.

Hereinafter, it demonstrates, referring drawings. In the following description, “up, down, left, and right” refers to the up, down, left, and right directions in each drawing unless otherwise specified.
[First embodiment]
FIG. 1A is a plan view showing a mirror holding mechanism in the optical system barrel according to the first embodiment of the present invention, and FIG. 1B is an enlarged view of an adhesive member of the holding mechanism.

  FIG. 2A is a side sectional view showing the mirror holding mechanism, and FIG. 2B is a plan view of a bowl-shaped member of the mechanism.

  A plate-like mirror 1 (optical element) shown in these drawings is arranged in an optical system barrel. The mirror 1 is held by three holding member sets 10 as shown in FIG. These holding member sets 10 are distributed and arranged on the side peripheral surface of the mirror 1 by 120 °. As shown in FIG. 2A, the mirror 1 is held in the optical system barrel by the three holding member sets 10, the ring 3, and the bowl-like member 5.

  First, the holding member set 10 will be described.

  As shown in FIG. 1, the holding member set 10 includes a connecting member 18. The connecting member 18 is a member for connecting to the ring 3 (see FIG. 2A). On the inner side of the connecting member 18 (the side facing the mirror 1 side peripheral surface), there are a central adhesive member 16 and two leaf springs 11 extending from the adhesive member 16 in both directions in the circumferential direction of the mirror 1. Is provided.

  A lattice-like groove 14 extending in the vertical and horizontal directions is formed on the surface (front surface) of the adhesive member 16 facing the peripheral surface on the mirror 1 side (see FIG. 1B). Due to the lattice-like grooves 14, the surface of the adhesive member 16 is divided into a plurality of parts. The surface of the adhesive member 16 is bonded to the peripheral surface of the mirror 1 with an adhesive 17 (in FIGS. 1 and 2A, the adhesive 17 is exaggerated and thickened). By dividing the surface of the adhesive member 16 into a plurality of parts, shrinkage when the adhesive 17 is solidified is suppressed, and deformation of the mirror 1 is suppressed. As the adhesive 17, a material that does not adversely affect the optical performance of the mirror 1, peripheral devices of the optical system barrel, and the like (for example, epoxy adhesive) is used. In particular, when an adhesive with less outgas is used, adverse effects such as adhesion of gas to the mirror 1 can be avoided.

  Each leaf spring 11 on both sides of the adhesive member 16 is formed by connecting two spring pieces 12 in series with a rigid piece 13 interposed therebetween. The length of the rigid piece 13 is at least twice the total length of the two spring pieces 12. The longer and thinner the spring piece 12, the smaller the rigidity. However, if the spring piece 12 is excessively thin, plastic deformation may occur at the time of processing or assembly, so that the minimum rigidity is ensured. Moreover, it is meaningful to shorten the length of the spring piece 12 in order to prevent buckling of the leaf spring.

  Actually, it is determined according to the rigidity of the mirror 1 (which is generally determined by the size of the mirror 1) and the required shape accuracy. As an example, the value of the spring piece can be selected in the range of 0.1 to 1 mm, and the length can be selected in the range of 1 mm to 10 mm. Furthermore, it is preferable that the length of the rigid piece 13 is at least twice the total length of the two spring pieces 12. For example, when the diameter of the mirror 1 is 200 mm and the thickness is 30 mm, the thickness of the spring piece 12 is about 0.5 mm, the length is about 3 mm, and the length of the rigid piece 13 is 15 mm. According to the observation, when such a leaf spring was used, the deformation of the mirror could be suppressed to 1 nm or less.

  Next, the ring 3 and the bowl-shaped member 5 will be described.

  As shown in FIG. 2A, the ring 3 is interposed between the mirror 1 and the optical system lens barrel flange 2. The connecting member 18 of each holding member set 10 is fixed to the lower end surface of the ring 3. The ring 3 and the optical system barrel flange 2 are connected by a hook-shaped member 5. The flange-shaped member 5 is formed by integrally forming an outer fitting portion 5a that is fitted on the ring 3 and a flange portion 5b that projects outward from the end of the outer fitting portion 5a. The outer fitting portion 5a and the ring 3, and the flange portion 5b and the optical system lens barrel flange 2 are coupled by screws (not shown).

  The thickness of the bowl-shaped member 5 is 1/10 or less of the thickness of the ring 3. As shown in FIG. 2B, a slit 5c is cut in the flange portion 5b. By interposing such a hook-shaped member 5, the deformation of the ring 3 occurs in a biased manner toward the thin low-rigid hook-shaped member 5. Therefore, the deformation of the entire ring 3 is reduced, and the deformation of the mirror 1 can be suppressed to a small level. Although it is not always necessary to provide the slit 5 c, in this embodiment, the rigidity is further reduced by forming the slit 5 c in the hook-shaped member 5, and the deformation of the ring 3 is more biased toward the hook-shaped member 5.

  As shown in FIG. 2A, a spacer 7 such as a washer can be interposed between the flange-shaped member 5 and the optical system barrel flange 2. In this case, since the space (gap) for the spacer 7 can be secured, it is possible to prevent the optical system lens barrel flange 2 and the flange-like member 5 from contacting each other than the holding portion. Or when using a flat washer as a spacer, a deformation | transformation of the collar part 5b of the collar-shaped member 5 at the time of attachment can also be suppressed.

According to such a holding mechanism, the leaf spring 11 is easily deformed in the vertical direction of the side surface of the mirror 1 (the radial direction of the mirror 1) at the contact portion between the side surface of the mirror 1 and the optical system barrel flange 2. For this reason, the mirror 1 itself is restrained in the vertical, horizontal, and front-rear directions, but even when the mirror 1 is deformed due to thermal expansion or the like, the leaf spring 11 escapes to suppress uneven local deformation of the mirror 1 to a small extent. Can do.
[Second Embodiment]
FIG. 3 is a side sectional view showing the optical system barrel of the exposure apparatus according to the second embodiment of the present invention.

  FIG. 4 is a plan sectional view showing a mirror in the lens barrel and a holding mechanism thereof.

  FIG. 5 is a front view showing a detailed configuration of a holding member of the holding mechanism.

  6A is a cross-sectional view taken along line XX in FIG. 5, FIG. 6B is an explanatory view showing a free state of the outer clamping member, and FIG. 6C is an adjustment of the outer clamping member. It is explanatory drawing which shows a back state.

  FIG. 7 is a cross-sectional view taken along line YY of FIG.

  FIG. 8 is a cross-sectional view taken along the line ZZ in FIG.

  FIG. 9 is a diagram showing a detailed structure of the elastic support member (two-dimensional leaf spring) of the holding mechanism shown in FIGS. 3 and 4. (A) is a front view, (B) is a side view, (C) is a top view, and (D) is a bottom view.

  3 and 4 show an end portion (holding protrusion) 201A of a plate-like mirror 201 (optical element). The holding projections 201A of the mirror 201 are integrally formed at three locations apart from each other on the mirror side peripheral surface. Each holding projection 201A is held in a state of being sandwiched between holding members 20 in this embodiment.

  Hereinafter, the detailed configuration of the holding member 20 will be described mainly with reference to FIGS.

  As clearly shown in FIG. 6, the holding member 20 includes an upper and lower holding member 21 that holds the holding protrusion 201 </ b> A of the mirror 201 up and down. The upper and lower clamping member 21 includes an upper pressing member 22 that contacts the upper surface of the mirror holding projection 201A, and a lower pressing member 23 that contacts the outer peripheral end and the lower surface of the mirror holding projection 201A. The upper presser member 22 and the lower presser member 23 are coupled by a screw S1 shown in FIG. The upper and lower pressing members 22 and 23 can be integrally formed.

  As shown best in FIG. 8, the upper pressing member 22 includes a central portion 25 that contacts the upper surface of the mirror holding projection 201 </ b> A, and end portions 27 on both sides of the central portion 25. The central portion 25 and both end portions 27 are integrally connected by a leaf spring 28 formed by wire cutting. The center portion 25 can be displaced up and down with respect to the end portion 27 by the leaf spring 28.

  As best shown in FIGS. 6 and 7, the lower presser member 23 has a side plate portion 31 located on the outer peripheral end side of the mirror holding projection 201A and a lower end portion 33 located on the lower surface side of the mirror holding projection 201A. It is a member having a substantially L-shaped cross section (see FIG. 6). The side plate portion 31 of the lower presser member 23 has a substantially flat plate shape, and a recess 31a is formed on the inner surface. The outer peripheral end of the mirror holding projection 201A is engaged with the recess 31a. As for the lower end part 33 of the lower pressing member 23, the convex part 33a (refer FIG. 8) is formed in the center upper side. The convex portion 33a contacts the lower surface side of the mirror holding projection 201A.

  As clearly shown in FIGS. 6 and 8, an upper screw shaft 36 and a lower screw shaft 37 are inserted into the center portion 25 of the upper pressing member 22 and the lower end portion 33 of the lower pressing member 23, respectively. These upper and lower screw shafts 36 and 37 are positioned in parallel to each other via the mirror holding projection 201A. These screw shafts 36 and 37 will be described later.

  As shown in FIG. 8, on the left end side of the mirror holding projection 201 </ b> A, a spring-equipped block (left clamping member) 41 is disposed between the end portion 27 of the upper pressing member 22 and the lower end portion 33 of the lower pressing member 23. Yes. The spring-loaded block 41 and the side plate portion 31 of the lower pressing member 23 are coupled by a screw S2 shown in FIG. This spring-loaded block 41 has a block main body 42 and a contact portion 43. The contact portion 43 is formed with a contact surface 43a that contacts the side surface of the mirror holding projection 201A. The left end portions of the upper and lower screw shafts 36 and 37 are screwed into the block main body 42 at the upper and lower sides with the contact portion 43 interposed therebetween.

  The block main body 42 is formed with a plate spring (horizontal plate spring) 45 for deformation in the horizontal direction (the radial direction of the optical element 1). As shown in FIG. 7, the horizontal leaf spring 45 is a part of the block main body 42 by engraving a groove along the vertical direction from both side surfaces toward the width center so that the thickness of the block main body 42 is reduced. It is formed as (thin wall part). The horizontal leaf springs 45 are formed at two locations in parallel with each other in the same plane. The horizontal plate spring 45 can incline (rotate) the block body 42 in the direction of the arrow α in FIG.

  As shown in FIG. 8, the abutting portion 43 of the block 41 with the spring is connected to the right side of the block main body 42 by a plate spring (upper and lower plate spring) 47 for tilting in the vertical direction. The upper and lower leaf springs 47 are cut and formed in the block body 42 by wire cutting. The contact surface 43 a of the contact portion 43 protrudes to the right side (mirror holding protrusion 201 </ b> A side) from the end surface of the block main body 42. The upper and lower leaf springs 47 can incline the abutting portion 43 in the direction in which the contact portion 43 inclines up and down with respect to the block body 42 (in the direction of arrow β in FIG. 8). In other words, the contact surface 43a of the contact portion 43 can be tilted by the entire upper and lower leaf springs 47.

  As shown in FIG. 8, on the right end side of the mirror holding projection 201 </ b> A, a right clamping member 51 and a deflecting plate 53 are disposed between the end portion 27 of the upper pressing member 22 and the lower end portion 33 of the lower pressing member 23. . Upper and lower screw shafts 36 and 37 are inserted through the upper and lower ends of the right clamping member 51. On the left end side (mirror holding projection 201A side) of the right clamping member 51, a mirror abutting projection 51a is formed that hits the side surface of the mirror holding projection 201A. On the right end side of the right clamping member 51 (on the side opposite to the mirror holding projection 201 </ b> A), a deflecting plate abutting projection 51 b that hits the center of the deflecting plate 53 is formed. The right clamping member 51 and the side plate portion 31 of the lower pressing member 23 are coupled by a screw S3 shown in FIG.

  The bending plate 53 is disposed on the right side of the right clamping member 51. The upper and lower screw shafts 36 and 37 are also inserted through the bending plate 53. Nuts 56 and 57 are screwed into the right end portions of the upper and lower screw shafts 36 and 37 on the outer side (right side in FIG. 8) of the bending plate 53, respectively. The flexure plate 53 can be flexed with the tightening amount of the nuts 56 and 57 with the flexure plate abutment protrusion 51b of the right clamping member 51 as a power point while being supported by the screw shafts 36 and 37. The central portion 25 of the upper pressing member 22 passing through the screw shafts 36 and 37, the lower end portion 33 of the lower pressing member 23, and the through holes of the right clamping member 51 are larger than the screw shafts 36 and 37. There is a gap on the outside.

  As shown in FIG. 5, two windows 39 are formed on the right side portion of the side plate portion 31 of the upper and lower clamping member 21. From each window 39, the right clamping member 51, the flexible plate 53, and the screw shafts 36 and 37 between them can be seen. By measuring the size between the right clamping member 51 and the bending plate 53 from these windows 39 with a microscope or the like, the bending amount of the bending plate 53 accompanying the tightening amount of the nuts 56 and 57 can be measured. Based on the amount of bending (the above-described dimensions) of the bending plate 53, the holding force (the force to be held between the spring-loaded block 41 and the right holding member 51) on the left and right sides of the mirror holding projection 201A can be adjusted.

  In addition, the code | symbol T of FIG. 5 is a tap hole for couple | bonding the side-plate part 31 and the member 202 of FIG.

  As clearly shown in FIG. 6, a U-shaped outer clamping member 61 is externally fitted to the upper and lower clamping members 21 of the holding member 20. A protrusion 62 a is formed on the inner side of the upper end portion 62 of the outer clamping member 61. The protrusion 62 a is in contact with the upper surface of the central portion 25 of the upper pressing member 22 of the upper and lower clamping member 21. The lower end portion 63 of the outer clamping member 61 is disposed in a recess 34 formed in the lower end portion 33 of the lower pressing member 23 of the upper and lower clamping member 21. Between the upper end part 62 and the lower end part 63 of the outer clamping member 61 is a strip-like intermediate part 64.

  As shown in FIG. 8, three through holes 63 a (center portion) and 63 b (both side portions) are opened in the lower end portion 63 of the outer clamping member 61. A positioning pin 35 is fixed to the lower end 33 of the lower presser member 23 concentrically with the central through hole 63a. The lower end portion of the positioning pin 35 protrudes downward through the through hole 63a at the center of the lower end portion 63. Further, two screw holes 33 b are formed in the lower end portion 33 of the lower pressing member 23 substantially concentrically with the two through holes 63 b in the lower end portion 63 of the outer clamping member 61. Screws 32 with holes are screwed into the screw holes 33b.

  The screw 32 with a hole can be moved up and down in the screw hole 33b by turning a wrench or the like through the through hole 63b of the lower end portion 63 of the outer clamping member 61. When the screw 32 with a hole is turned down, the lower end of the screw hits the upper surface of the lower end portion 63 of the outer clamping member 61 and pushes down the lower end portion 63. This push-down force is transmitted to the upper end portion 62 of the outer clamping member 61, and the upper end portion 62 also tends to be lowered. This pressing force is transmitted from the protrusion 62a of the upper end portion 62 to the mirror holding protrusion 201A via the center portion 25 of the upper pressing member 22. That is, when the screw 32 with a hole is lowered, the force for sandwiching the mirror holding projection 201A between the upper pressing member 22 and the lower pressing member 23 of the upper and lower clamping member 21 is increased. Conversely, when the screw 32 with the hole is turned up and the lower end of the screw is separated from the upper surface of the lower end portion 63 of the outer clamping member 61, the mirror holding projection 201A is clamped between the upper pressing member 22 and the lower pressing member 23 of the upper and lower clamping member 21. The power is reduced.

  Here, with reference to FIG. 6 (B) and (C), the deformation | transformation (adjustment of the pinching force) of the outer clamping member 61 accompanying the upper and lower sides of the screw 32 with a hole is demonstrated. As shown in FIG. 6 (B), the outer clamping member 61 maintains a normal U-shape until the lower end of the screw hits the upper surface of the lower end portion 63 of the outer clamping member 61. When the holed screw 32 is lowered from this state and the lower end of the screw pushes down the lower end portion 63 of the outer clamping member 61, the intermediate portion 64 is mainly bent and the outer clamping member 61 is deformed as shown in FIG. To do. The deformation amount δ of the outer clamping member 61 at this time can be adjusted according to the lowered position of the screw 32 with a hole.

  Conventionally, there is no such clamping member, and the mirror holding projection is directly pressed by a screw, and the force for pressing the mirror holding projection is managed by the tightening torque of the screw. However, in such management, since the pressing force is difficult to be constant even if the torque is constant, the pressing force of the mirror holding projection is difficult to stabilize, and therefore the mirror deformation is not constant. On the other hand, since the holding member 20 described above can manage the force for pressing the mirror holding projection in a visible manner, the holding force necessary for holding can be reliably obtained. That is, the holding member 20 can prevent the mirror from being deformed as much as possible, and can always manage the inevitable deformation of the mirror stably.

  Thus, when the holding member 20 of the present embodiment is used, the mirror holding projection 201A can be sandwiched from four directions, up, down, left, and right. The mirror holding projections 201A can be sandwiched flexibly and perfectly right and left and up and down by the action of the leaf springs 45 and 47 of the block 41 with spring and the leaf spring 28 of the upper pressing member 22. As a result, local deformation of the mirror holding projection 201A is suppressed, and the frictional force of the abutting portion is increased, thereby suppressing the displacement of the mirror holding projection 201A. Alternatively, a high holding force of the mirror holding protrusion 201A can be realized. Furthermore, since the plate spring 28 of the upper holding member 22 and the plate springs 45 and 47 of the spring-loaded block 41 are deformed and escape, an excessive force is not applied to the mirror holding projection 201A, and the deformation is suppressed to be small. Can do.

  Returning to FIG. 3 and FIG.

As shown in FIG. 3, an elastic support member (elastic support member 1) 70 is disposed below the holding member 20. On the other hand, as shown in FIG. 4, elastic support members (elastic support members 2) 70 ′ are also arranged on the left and right sides of the holding member 20. These elastic support members 70 and 70 ' are two-dimensional leaf springs shown in detail in FIG. Since the structure of each elastic support member (two-dimensional leaf spring) 70, 70 ' is substantially the same, the configuration of the two-dimensional leaf spring 70 will be described below with reference to FIG.

  As shown in FIG. 9, the two-dimensional leaf spring 70 is formed so that two sets of leaf springs are orthogonal to each other in one block. More specifically, the two-dimensional leaf spring 70 includes a central block portion 71. The block portion 71 is a solid body having a substantially rectangular parallelepiped shape. At the upper end and the lower end of the same portion 71, attachment piece portions 72, 73 projecting in a blade shape on the left and right sides (block longitudinal direction) are formed, respectively. In the block portion 71, cut grooves 75 and 75 ′ and 76 and 76 ′ forming two sets of leaf springs are cut so as to be orthogonal to each other by wire cutting with a single stroke. The cut grooves 75 and 75 'and the cut grooves 76 and 76' are symmetrical with respect to the center lines C1 (see FIG. 9A) and C2 (see FIG. 9B) of the block portion 71, respectively. It is cut into. For example, the width of each groove is about 0.3 mm.

  The notch groove 75 (and the notch groove 75 'symmetrical thereto) is formed so that the following first to fourth notch portions 75a to 75d are connected; as shown in FIG. The one cut portion 75a extends from the vicinity of the boundary portion between the side portion of the block portion 71 and the upper end attachment piece portion 72 to the vicinity of the center line C1. The second notch 75b bends 90 ° from the end of the first notch 75a and extends parallel to the center line C1. The third cut portion 75c is cut in a U shape so as to swell from the end of the second cut portion 75b to the side away from the center line C1. The fourth cut portion 75d bends 90 ° from the end of the third cut portion 75c and extends parallel to the center line C1 (extends on the same straight line as the second cut portion 75b). Thin leaf springs 77X and 77Y are formed between the second cut portions 75b and 75b ′ and between the fourth cut portions 75d and 75d ′.

  The notch groove 76 (and the notch groove 76 'symmetrical thereto) is formed so that the following first to fourth notch portions 76a to 76d are connected; as shown in FIG. The one cut portion 76a extends from the vicinity of the boundary portion between the block portion 71 side portion and the lower end attachment piece portion 73 to the vicinity of the center line C2. The second notch 76b bends 90 ° from the end of the first notch 76a and extends parallel to the center line C2. The third cut portion 76c is cut in a U shape so as to swell from the end of the second cut portion 76b to the side away from the center line C2. The fourth cut portion 76d bends 90 ° from the end of the third cut portion 76c and extends parallel to the center line C2 (extends on the same straight line as the second cut portion 76b). Thin leaf springs 78X and 78Y are formed between the second cut portions 76b and 76b 'and between the fourth cut portions 76d and 76d'.

  By cutting the cut grooves 75, 75 'and 76, 76', the block 71 can be displaced in the directions of arrows (both horizontal and tilted (rotated)) in FIGS. 9A and 9B. It is. The wire cut processing used for forming each groove can perform precise processing without applying excessive force to the block portion 71. With such a two-dimensional leaf spring 70, two sets of leaf spring functions can be realized in a small space in one block.

  Pin holes 71a and 71b are formed at the centers of the upper and lower end surfaces of the block portion 71 of the two-dimensional leaf spring 70, respectively. The positioning pin 35 (see FIG. 3 and the like) engages with the upper pin hole 71a. The hole 72a of the upper mounting piece 72 and the hole 73a of the lower mounting piece 73 are insertion holes through which screws for fixing the two-dimensional leaf spring 70 are inserted.

  Returning to FIG. 3 and FIG.

  As shown in FIG. 3, the holding member 20 of the mirror holding projection 201 </ b> A and the two-dimensional plate spring 70 are screw-coupled in a state where the positioning pin 35 of the holding member 20 is engaged with the pin hole 71 a of the two-dimensional plate spring 70. . At this time, the center of the two-dimensional leaf spring 70 coincides with the center of the positioning pin 35 of the holding mechanism. In this way, by aligning the center and aligning the approximate center of the positioning pin 35 with the surface of the two-dimensional leaf spring 70, even if gravity or impact is applied to the mirror 201, the mirror holding projection 201A can be gripped. Unreasonable power is not applied. Therefore, deformation of the mirror 201 can be suppressed to a small level. The holding member 20 is intended to be integrated with the mirror holding protrusion 201A, and the holding member 20 itself is not distorted.

A two-dimensional leaf spring (elastic support member 1) 70 attached to the lower side of the holding member 20 as shown in FIG. 3 supports the holding member 20 with high rigidity in the direction of gravity, and the mirror circumferential direction and radial direction. And it supports flexibly in the tilt direction. On the other hand, as shown in FIG. 4, two-dimensional leaf springs (elastic support members 2) 70 ' attached to the left and right of the holding member 20 support the holding member 20 with high rigidity in the circumferential direction of the mirror. Flexible support in the mirror radial direction. According to such a mirror holding mechanism, the distortion that occurs when the holding member 20 and the mirror 201 are coupled (distortion caused by the flatness of both contact surfaces) is caused by the deformation of each two-dimensional leaf spring 70 ′ . Can be absorbed. Therefore, deformation of the mirror 201 at the time of coupling can be suppressed.

  As shown in FIG. 3, the lower end attachment piece 73 of the two-dimensional leaf spring 70 is fixed to the ring 3. Further, position adjusting mechanisms 80, 81, 82 of the mirror 201 are arranged in a state of being sandwiched between the ring 3 and the optical system barrel flange 2. On the other hand, a fixing mechanism 90 is arranged so as to connect the ring 3 and the optical system barrel flange 2.

  The position adjustment mechanism 80 adjusts the position of Z, θx, and θy of the mirror 201 (refer to the arrow directions in FIG. 3 for X, Y, and Z). On the other hand, the position adjustment mechanisms 81 and 82 adjust the X, Y, and θz positions of the mirror 201 (refer to the arrow directions in FIG. 3 for X, Y, and Z). The position adjustment mechanism 80 is operated by an actuator such as a DC motor or a pico motor (PZT motor).

  When a highly accurate aspherical mirror is used as the mirror 201, the required positional accuracy may be as small as about 1 μm. When the mirror 201 is a spherical mirror, the lateral shift often generates the same aberration as the tilt. On the other hand, when the mirror 201 is an aspherical mirror, the amount and type of aberration are not necessarily the same. Since the position adjustment mechanisms 80, 81, 82 of this embodiment have both a lateral shift function and an inclination function, and an interval adjustment function (that is, X, Y, Z, θx, θy, θz adjustment), By appropriately adjusting these functions and correcting the position error of the mirror 201, desired wavefront aberration and resolution can be easily obtained.

  Further, the position adjusting mechanisms 80, 81, 82 can be configured by a driving amount reducing mechanism (lever mechanism) as shown in FIG.

  FIG. 10A is a plan view mainly showing an example of the drive amount reduction mechanism of the position adjustment mechanism (81 82) in the present embodiment, and FIG. 10B is an example of the position adjustment mechanism (80). It is a block diagram mainly shown.

  The left lever mechanism (Y-direction position adjusting mechanism) 81 and the right lever mechanism (YX-direction position adjusting mechanism) 82 in FIG. 10A are finely adjusted for the X, Y, and θz positions of the mirror 201 as described above. It is a mechanism that performs. FIG. 10B shows details of adjusting mechanisms 80 (three in total) arranged at intervals of 120 ° around the center ring 3 (shown virtually) in FIG. These three adjusting mechanisms 80 are mechanisms for adjusting the positions of Z, θx, and θy of the mirror 201 as described above. As shown in FIG. 3, each mechanism 80, 81, 82 is arranged immediately below the holding mechanism (see the support point F in FIGS. 3 and 10A). Since the adjusting mechanism 80 is disposed immediately below the ring 3, the rigidity of the ring 3 can be reduced. However, the adjustment mechanism 80 does not necessarily need to be disposed directly below the holding mechanism.

  The drive amount reduction mechanism reduces the movement of the actuator A and transmits it to the ring 3. By adjusting the position of the ring 3, the position of the mirror 201 is adjusted. The drive amount reduction mechanism includes a lever lever 85. As shown in FIG. 10B, the lever lever 85 includes a fixed portion 85a fixed to the optical system lens barrel flange 2, a moving portion 85b connected to the ring 3 via a two-dimensional leaf spring 70, A leaf spring 86 is provided to connect these two parts. The fixed portion 85a and the moving portion 85b are arranged in parallel with the leaf spring 86 interposed therebetween.

  In the drive amount reduction mechanism (position adjustment mechanism 80), when the actuator A is operated, the moving portion 85b of the lever lever 85 moves in the direction of the arrow Z1 in FIG. The movement of the moving portion 85b moves the two-dimensional leaf spring 87 in the direction of arrow Z2 in FIG. 10B with the leaf spring 86 as a fulcrum. At this time, due to the lever action of the lever lever 85, the movement of the moving portion 85 b (drive amount of the actuator A) is reduced and transmitted to the two-dimensional leaf spring 70.

  When the actuators A are actuated in the same manner as described above, the drive amount reduction mechanisms (position adjustment mechanisms 81 and 82) transmit the reduced drive amounts to the two-dimensional plate springs using the plate springs 86 as fulcrums. This driving amount acts on the ring 3 at a support point (power point) F from each two-dimensional leaf spring. In the position adjustment mechanism 81, the two-dimensional leaf spring 88 moves in the direction of arrow Y in FIG. On the other hand, in the position adjustment mechanism 82, the two two-dimensional leaf springs 88 move in the directions of arrows Y and X in FIG.

  With such a drive amount micro mechanism (position adjustment mechanisms 80, 81, 82), the position of the mirror 201 can be finely adjusted.

By the way, after the position of the mirror 201 is adjusted by the above-described position adjusting mechanisms 80, 81, and 82, the position must be maintained. However, the position adjusting mechanisms 80, 81, and 82 may not have sufficient ability to maintain the position. is there. In such a case, the fixing mechanism 90 shown in FIG. 3 is used.
FIG. 12A is a plan view showing an example of the fixing mechanism of the optical barrel according to the present invention, and FIG. 12B is a side view of the fixing mechanism.

  As shown in FIG. 12 (and FIG. 3 described above), the fixing mechanism 90 includes a clamp member 91 that connects the optical system lens barrel flange 2 and the ring 3, and a leaf spring 92. The leaf spring 92 serves to prevent the position of the ring 3 from shifting when the optical system barrel flange 2 and the ring 3 are coupled to the clamp member 91 with screws or the like. The leaf spring 92 is formed by connecting two spring pieces 95 in series with a rigid piece 96 interposed therebetween. The two spring pieces 95 are located in the same plane. Three or more pairs of the leaf springs 92 are distributed along the circumferential direction of the ring 3. At this time, the leaf springs 92 arranged in a distributed manner are arranged in different directions.

  If the leaf springs 92 are arranged in this way, after the position adjustment of the holding member 20 is performed, the movements of the leaf springs 92 are restrained and there is no degree of freedom, and the mirror position can be maintained. In particular, as shown in the figure, when the three fixing mechanisms 90 are dispersedly arranged at intervals of 120 ° and the direction of the leaf springs 92 is also changed at intervals of 120 °, the fixing mechanisms 90 can be restrained almost completely. Three sets are ideal because of the best balance, but it is also possible to use four or more sets if you want to fix them more firmly. When the number of groups is four or more, the ring 3 can be fixed more strongly although it is instable and excessively constrained. At this time, even if the ring 3 is somewhat distorted, the two-dimensional leaf spring 70 is spring-deformed, so that the distortion of the ring 3 has little influence on the deformation of the mirror 201. Further, since the allowable distortion amount of the ring 3 is larger in each stage than the allowable distortion amount of the mirror 201, it can be said that there is no big problem.

It is also possible to correct the mirror shape error with the actuator shown in FIG. The correction of the mirror shape error described here is an adjustment different from the fine position adjustment of the mirror described above.
FIGS. 11A and 11B are diagrams illustrating an example in which a two-dimensional actuator (shape adjusting mechanism) is provided between a two-dimensional leaf spring and a ring.

  In FIG. 11, a two-dimensional actuator B is provided between the two-dimensional leaf spring 70 and the ring 3 shown in FIG. When the two-dimensional actuator B is operated, a displacement in the circumferential direction or the radial direction can be applied to the two-dimensional leaf spring 70. FIG. 11A schematically shows a state where the two-dimensional leaf spring 70 is displaced in the radial direction by the two-dimensional actuator B and the moment force indicated by the arrow M1 is applied to the holding projection 201A of the mirror 201. FIG. On the other hand, FIG. 11B schematically illustrates a state in which the two-dimensional leaf spring 70 is displaced in the circumferential direction by the two-dimensional actuator B and the moment force indicated by the arrow M2 is applied to the holding projection 201A of the mirror 201. When the mirror 201 is deformed, the wavefront aberration changes, and based on this, a moment force that gives a desired wavefront aberration is applied to correct the mirror shape error.

1,201 Mirror (Optical element)
DESCRIPTION OF SYMBOLS 1A, 201A Mirror holding protrusion 2 Optical system lens barrel flange 3 Ring 5 Gutter-like member 5a Outer fitting part 5b Gutter part 5c Slit 7 Spacer 10 Holding member set 11 Leaf spring 12 Spring piece 13 Rigid piece 14 Groove 16 Adhesive member 17 Adhesive 18 connecting member 20 holding member 21 upper and lower clamping member 22 upper pressing member 23 lower pressing member 25 center portion 27 end portion 28 leaf spring 31 side plate portion 32 screw with hole 33 lower end portion 35 positioning pin 36 upper screw shaft 37 lower screw shaft 39 window 41 Block with Spring (Left Holding Member) 42 Block Body 43 Abutting Portion 43a Abutting Surface 45 Leaf Spring (Horizontal Leaf Spring) 47 Leaf Spring (Upper and Lower Leaf Springs)
51 Right clamping member 51a Mirror abutting projection 51b Bending plate abutting projection 53 Bending plate 56, 57 Nut 61 Outer clamping member 62 Upper end 62a Projection 63 Lower end 63a, 63b Through hole 64 Deformed portion 70 Two-dimensional leaf spring 71 Block portion 71a, 71b Pin holes 72, 73 Mounting pieces 75, 75 ', 76, 76' Cut grooves 77X, 77Y, 78X, 78Y Leaf spring 80 Adjustment mechanism 81 Y-direction position adjustment mechanism 82 YX-direction position adjustment mechanism 85 Lever lever 85a Fixed portion 85b Moving portion 86 Leaf spring 90 Fixing mechanism 91 Clamp member 92 Leaf spring 95 Spring piece 96 Rigid piece A, B Actuator

Claims (10)

A mechanism for holding the optical element in the optical barrel;
A holding member for holding an end of the optical element;
A first elastic support member that flexibly supports the holding member in the radial direction, the circumferential direction, and the tilt direction of the optical element, and supports the holding member with high rigidity in the gravity direction ;
A second elastic support member that flexibly supports the holding member in the radial direction and the gravity direction and supports the circumferential direction with high rigidity ;
An optical element holding mechanism comprising: The first elastic support member and / or the second elastic support member are arranged in series in the direction of supporting with high rigidity and are composed of two sets of leaf springs that are easily bent in the flexible direction. The optical element holding mechanism according to claim 1. 3. The optical element holding mechanism according to claim 2, wherein the two sets of leaf springs are two-dimensional leaf springs formed so as to be orthogonal to one block. 4. The optical element according to claim 2, wherein the centers of the two sets of leaf springs of the elastic support member coincide with the centers of the holding protrusions at the ends of the holding member and the optical element. Retention mechanism. The set of said holding member, said 1st elastic support member, and said 2nd elastic support member is disperse | distributed 3 or more sets by the side periphery of the said optical element among Claims 1-4 characterized by the above-mentioned. The optical element holding mechanism according to any one of claims. An optical element holding mechanism;
An optical system barrel comprising a position adjusting mechanism for the optical element and / or a shape adjusting mechanism for the optical element,
An optical system barrel, wherein the optical element holding mechanism is the optical element holding mechanism according to any one of claims 1 to 5. The optical system barrel according to claim 6, wherein the shape adjusting mechanism applies a moment to the optical element via the holding mechanism to correct a shape error of the optical element. The optical system barrel according to claim 7, wherein the shape adjusting mechanism includes an actuator that applies a horizontal displacement to the holding mechanism. The optical according to any one of claims 6 to 8, wherein the position adjustment mechanism includes an actuator and a drive amount reduction mechanism that reduces the movement of the actuator and transmits the reduction to the optical element holding mechanism. System barrel. An exposure apparatus that selectively irradiates a sensitive substrate with energy rays to form a pattern,
An exposure apparatus comprising the optical system barrel according to any one of claims 6 to 9, wherein the energy beam optical system is mounted.