JPWO2004021419A1 - Projection optical system and exposure apparatus - Google Patents

Abstract

The projection optical system 25 that holds the optical element without deteriorating the surface accuracy of the optical element includes an upper barrel 32, a horizontal barrel 33, a lower barrel 34, a coupling body 54, and a flange 55. The upper barrel 32, the horizontal barrel 33, and the lower barrel 34 are coupled to the coupling body 54 without contacting each other. The connecting body 54 is supported by the flange 55, and the flange 55 is supported by the lower mount 14.

Description

  The present invention is provided in 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, and the exposure apparatus. The present invention relates to a projection optical system.

A conventional projection optical system is a refraction type projection optical system composed of a large number of lenses arranged in the optical axis direction in order to accurately project an image of a predetermined pattern formed on a mask onto a substrate. Mainstream. The refractive optical system is an optical system including only a transmission optical member such as a lens without including a reflecting mirror having a power (a concave reflecting mirror or a convex reflecting mirror). These lenses are held inside the lens barrel. The lens barrel has a flange portion formed on the outer surface thereof. Therefore, the conventional projection optical system is supported on the frame of the exposure apparatus main body via the flange portion of the lens barrel.
By the way, as the degree of integration of semiconductor elements and the like improves, the resolution (resolution) required for the projection optical system of the exposure apparatus is increasing. As a result, in order to satisfy the resolution requirement of the projection optical system, it is necessary to shorten the wavelength of the illumination light (exposure light) and increase the numerical aperture (NA) of the projection optical system.
However, when the wavelength of the illumination light is shortened, light absorption becomes significant. Therefore, the types of glass materials (optical materials) that can be used are limited. In particular, when the wavelength of illumination light is 180 nm or less, the practical glass material is limited to fluorite. As a result, it is difficult to correct chromatic aberration in the refraction type projection optical system. As described above, there is a limit to the chromatic aberration that can be tolerated in a refraction type projection optical system made of a single glass material. However, when the laser light source is extremely narrowed, an increase in cost and a decrease in output of the laser light source are inevitable.
Therefore, a catadioptric projection optical system having a reflective optical element that does not cause chromatic aberration has been proposed. The catadioptric optical system includes, as a reflective optical element, an optical path bending mirror that deflects exposure light that has passed through a circuit pattern on a mask, and a concave reflecting mirror that reflects exposure light deflected by the optical path bending mirror. .
In the conventional catadioptric projection optical system, the lens barrel includes at least a first partial lens barrel (vertical lens barrel) whose optical axis extends in the vertical direction and a second partial lens barrel whose optical axis extends horizontally. (Horizontal lens barrel). If the horizontal lens barrel is simply attached to one side surface of the vertical lens barrel, there is a possibility that an offset load based on the weight of the horizontal lens barrel may act on the vertical lens barrel. Uneven load distorts the vertical column. When the vertical lens barrel is distorted, the surface accuracy of the optical element accommodated in the vertical lens barrel is deteriorated, and an unpredictable aberration may occur in the projection optical system. The occurrence of this unpredictable aberration leads to deterioration of exposure accuracy.
It is conceivable to reduce the influence of the weight of the horizontal lens barrel on the vertical lens barrel by supporting the horizontal lens tube on the frame of the exposure apparatus main body or providing a support device for supporting the horizontal lens barrel separately. However, this method requires a positioning operation of the horizontal lens barrel with respect to the vertical lens barrel, and causes a new problem that leads to an increase in the size of the exposure apparatus.

The present invention has been made paying attention to the problems of the prior art, and an object thereof is to provide a projection optical system capable of holding the optical element without deteriorating the surface accuracy of the optical element. is there. 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 improving exposure accuracy.
According to an aspect of the present invention, there is provided a projection optical system that projects an image of a pattern that is supported on a gantry and formed on a mask onto a predetermined surface. The first holding member holds at least one first optical element disposed on the first optical axis. The second holding member holds at least one second optical element disposed on the second optical axis that intersects the first optical axis. The connecting member has a first connecting part connected to the first holding member and a second connecting part connected to the second holding member. The projection optical system includes an attachment member for attaching the connecting member to the gantry.
It is preferable that the first holding member connected to the first connecting portion does not contact the second holding member connected to the second connecting portion.
The first connecting portion is connected to one end portion of the first holding member, the second connecting portion is connected to one end portion of the second holding member, and the first holding member and the second holding portion are connected. In the state where the holding member is connected to the connecting member, the optical axis of the first optical element held by the first holding member and the light of the second optical element held by the second holding member It is preferable that the axes are oriented in different directions.
In one embodiment, the attachment member is provided integrally with the connection member.
The projection optical system according to an embodiment is provided with the coupling member sandwiched between the first holding member, the first optical axis, an axis parallel to the first optical axis, or the first A third holding member for holding at least one third optical element disposed on an axis intersecting the optical axis, wherein the connecting member is connected to the third holding member; Have
It is preferable that the third holding member is connected to the third connecting portion without the first holding member, the second holding member, and the third holding member being in contact with each other.
In one embodiment, the attachment member is provided on the third holding member, and the connecting member is supported by the third holding member.
In one embodiment, the first holding member includes at least one holding frame that holds the at least one first optical element, and the second holding member includes the at least one second optical element and a concave reflecting mirror. Including at least one holding frame.
In one embodiment, the at least one first optical element constitutes a first imaging optical system, and the at least one second optical element and the concave reflecting mirror constitute a second imaging optical system.
The holding frame of the first holding member and the holding frame of the second holding member are preferably made of the same material.
A projection optical system according to an embodiment includes a plurality of optical elements including the at least one first optical element, a first imaging optical system that forms a first intermediate image of the pattern, and the first intermediate image. A first optical path bending mirror that is disposed in the vicinity of the first intermediate image and deflects the light beam toward the first intermediate image or the light beam from the first intermediate image, the at least one second optical element, and a concave reflecting mirror; A second imaging optical system that forms a second intermediate image in the vicinity of the formation position of the first intermediate image using a light beam from the first intermediate image, and a formation position of the second intermediate image. A plurality of optical elements including a second optical path bending mirror disposed in the vicinity and deflecting a light beam directed to the second intermediate image or a light beam from the second intermediate image, and the at least one third optical element; Using the light flux from the second intermediate image, The statuette and a third imaging optical system for imaging on a substrate.
In one embodiment, the first holding member includes a plurality of holding frames that hold a plurality of optical elements including the at least one first optical element, and the second holding member is bent in the first optical path. A plurality of holding frames for holding a mirror, the at least one second optical element, the concave reflecting mirror, and the second optical path bending mirror; and the third holding member includes the at least one third optical element. A plurality of holding frames for holding the plurality of optical elements.
The connecting member includes an optical element exchanging mechanism for exchanging at least one optical element held in at least one of the first, second, and third holding members and accommodated in the connecting member. It is preferable to have.
In one embodiment, the second optical element includes a first optical path bending mirror that deflects a light beam from the first intermediate image formed by at least a part of the first optical element or a light beam toward the first intermediate image; A reflective optical element having a second optical path bending mirror that deflects a light beam from the second intermediate image formed by the second optical element based on the first intermediate image or a light beam directed to the second intermediate image. The optical element exchanging mechanism is for exchanging the reflective optical element.
The connecting member is preferably made of a ceramic material.
At least one of the first, second, and third holding members and the gantry is formed of a material having a linear expansion coefficient that is different from the linear expansion coefficient of the material constituting the connection member. The difference in coefficient of linear expansion is greater than a predetermined value, and the first, second and third holding members, at least one of the mounts and the connecting member are connected via a flexure mechanism. preferable.
The projection optical system is provided in an exposure apparatus used in a lithography process for manufacturing a device by exposing a pattern image formed on a mask onto a substrate.

FIG. 1 is a schematic view of an exposure apparatus according to the first embodiment of the present invention.
FIG. 2 is a sectional view of the projection optical system of FIG.
FIG. 3 is a partial cross-sectional perspective view of the horizontal barrel and connection body of FIG. 1.
4 is a cross-sectional view taken along line 4-4 of FIG. 2. FIG. 5 is a partially enlarged cross-sectional view of the bolt mounting portion of FIG.
FIG. 6 is a sectional view of a projection optical system according to the second embodiment of the present invention.
FIG. 7 is a sectional view of a projection optical system according to the third embodiment of the present invention.
FIG. 8 is a sectional view of a projection optical system according to the fourth embodiment of the present invention.
FIG. 9 is a flowchart of an example of manufacturing a device using the exposure apparatus of the present invention.
FIG. 10 is a detailed flowchart of FIG.

The projection optical system and exposure apparatus according to the first embodiment of the present invention will be described below.
As shown in FIG. 1, the projection optical system 25 of the first embodiment is a catadioptric type, and is provided in a so-called step-and-scan type scanning projection exposure apparatus 11.
1, the X axis is perpendicular to the paper surface of FIG. 1, the Z axis is parallel to the first optical axis AX of the projection optical system 25, the Y axis is parallel to the paper surface of FIG. 1, and the first optical axis AX. Is perpendicular to.
The exposure apparatus 11 uses, for example, F as a light source 21 for supplying exposure light EL having a wavelength in the vacuum ultraviolet region. ₂ A laser (oscillation center wavelength 157.624 nm) is provided. The exposure light EL emitted from the light source 21 uniformly illuminates the reticle R as a mask on which a predetermined circuit pattern is formed via the illumination optical system 22. A beam matching unit (BMU) 23 is provided between the light source 21 and the illumination optical system 22, and the light source 21 and the exposure apparatus main body 12 are optically connected by the BMU 23. The exposure light EL emitted from the light source 21 is guided to the exposure apparatus main body 12 via the BMU 23. The space from the light source 21 to the optical element closest to the reticle R in the illumination optical system 22 is replaced with a gas having a low absorption rate of the exposure light EL, for example, an inert gas such as helium gas or nitrogen, or It is kept in a vacuum state.
The exposure apparatus main body 12 includes an upper frame 15, a lower frame 14, and a surface plate 13 that supports the frames 14 and 15. A reticle stage 24 is disposed on the upper pedestal 15, and the reticle R is held parallel to the XY plane by a reticle holder (not shown). A pattern to be transferred is formed on the reticle R, and the pattern area is sequentially illuminated with rectangular exposure light EL having a long side along the X direction and a short side along the Y direction. The The reticle stage 24 can be moved two-dimensionally along the reticle surface (that is, the XY plane) by a drive system (not shown). The position (coordinates) of reticle stage 24 is measured by an interferometer (not shown).
The light that has passed through the reticle R is projected onto a wafer W as a substrate coated with a photosensitive material via the projection optical system 25, and an image of a pattern formed on the reticle R is formed on the wafer W. The wafer W is held in parallel with the XY plane by a wafer stage 26 disposed on the surface plate 13 of the exposure apparatus main body 12 via a wafer holder (not shown). A rectangular exposure region having a long side along the X direction and a short side along the Y direction on the wafer W so as to optically correspond to the rectangular illumination region on the reticle R. A pattern image is formed. The wafer stage 26 can be moved two-dimensionally along the wafer surface (that is, the XY plane) by a drive system (not shown). The position (coordinates) of the wafer stage 26 is measured by an interferometer (not shown).
As shown in FIG. 2, in the projection optical system 25, a cover glass 27 as a first optical element disposed on the side closest to the reticle R, and a third optical element disposed on the side closest to the wafer W are used. The internal space partitioned between the cover glass 28 is kept airtight. The internal space of the projection optical system 25 is preferably replaced with an inert gas such as helium gas or nitrogen, or is preferably maintained in a substantially vacuum state.
The reticle R and the reticle stage 24 are disposed between the illumination optical system 22 and the projection optical system 25 and are surrounded by a sealed casing (not shown). The internal space of the casing is filled with an inert gas such as nitrogen or helium gas, or is maintained in a substantially vacuum state.
The wafer W and the wafer stage 26 are disposed between the projection optical system 25 and the wafer stage 26 and are surrounded by another sealed casing (not shown). The internal space of the casing is filled with an inert gas such as nitrogen or helium gas, or is maintained in a substantially vacuum state.
Thus, an atmosphere in which the exposure light EL is hardly absorbed is formed in the optical path from the light source 21 to the wafer W.
As described above, the illumination area on the reticle R and the exposure area on the wafer W defined by the illumination optical system 22 have a rectangular shape having short sides along the Y direction. Accordingly, the positions of the reticle R and the wafer W are controlled using the drive system and the interferometer, and the reticle stage 24 and the wafer stage 26 are arranged along the short side direction of the rectangular exposure area and illumination area, that is, the Y direction. , And the reticle R and the wafer W are moved (scanned) synchronously in the same direction, so that the wafer W has a width equal to the long side of the exposure region and the scanning amount (movement of the wafer W) The reticle pattern is exposed to an area having a length corresponding to (amount).
Next, the projection optical system 25 will be described.
As shown in FIGS. 1 and 2, the projection optical system 25 has a first lens barrel module (upper lens barrel) 32 as a first holding member and a second holding member around a connecting member 31. The second lens barrel module (horizontal lens barrel) 33 and a third lens barrel module (lower lens barrel) 34 as a third holding member. All refractive optical elements (lenses) of the projection optical system 25 are fluorite (CaF ₂ Crystal).
The upper lens barrel 32 is disposed on the side close to the reticle R on the first optical axis AX of the projection optical system 25. The upper lens barrel 32 has a substantially cylindrical shape, and holds a first imaging optical system 35 for forming a first intermediate image of the pattern of the reticle R therein. The first imaging optical system 35 has a plurality of refractive optical elements. The upper lens barrel 32 is formed by laminating a plurality (four in this embodiment) of holding frames 37u each holding one or a combination of a lens 36a as a first optical element and a cover glass 27. . Each holding frame 37u is made of a metal material such as stainless steel or titanium alloy.
Of the plurality of holding frames 37u, the holding frame 37uw provided at the end far from the reticle R (that is, the lower end of the upper barrel 32) has a smaller outer diameter than the outer diameters of the other holding frames 37u. It has the edge part 32a which has. The end 32 a is inserted into the connecting member 31, and the upper barrel 32 is connected to the connecting member 31. Further, in order to avoid interference between the horizontal lens barrel 33 connected to the connecting member 31 and the upper lens barrel 32, a concave portion (a meat removal portion) 32b is provided in a part of the end portion 32a.
The horizontal barrel 33 holds a second imaging optical system 39 for forming a second intermediate image. The horizontal barrel 33 is arranged so that the optical axis (second optical axis AX ′) of the second imaging optical system 39 is orthogonal to the first optical axis AX. The second imaging optical system 39 includes a right-angle reflecting mirror 44 as a reflecting optical element to be described later, a negative lens 40 as a second optical element, and a concave reflecting mirror 41. The negative lens 40 and the concave reflecting mirror 41 are arranged in a vertically placed state so that the second optical axis AX ′ is oriented in the horizontal direction. The right-angle reflecting mirror 44 includes a first optical path folding mirror 38 and a second optical path folding mirror 42. The horizontal barrel 33 is formed by connecting a plurality of holding frames 37a, 37b, and 37c that hold the right-angle reflecting mirror 44, the negative lens 40, and the concave reflecting mirror 41.
A first optical path bending mirror 38 is disposed in the vicinity of the first intermediate image formed by the first imaging optical system 35. The exposure light EL deflected by the first optical path bending mirror 38 is guided to the concave reflecting mirror 41 through the negative lens 40 and reflected by the concave reflecting mirror 41. The exposure light EL reflected by the concave reflecting mirror 41 passes through the negative lens 40 again to form a second intermediate image in the vicinity of the first intermediate image forming position, in the present embodiment, in the vicinity of the second optical path folding mirror 42. To do. The second intermediate image is approximately the same size as the first intermediate image and is a secondary image of the pattern.
That is, the second optical path bending mirror 42 is disposed in the vicinity of the second intermediate image formed by the second imaging optical system 39, and the exposure light EL toward the second intermediate image or the exposure light EL from the second intermediate image. Is deflected toward the refractive third imaging optical system 43. The right-angle reflecting mirror 44 is formed on a base material made of a metal material (stainless steel or the like), a low thermal expansion ceramic (such as silicon carbide) or the like. The right-angle reflecting mirror 44 has two inclined surfaces orthogonal to each other, the reflecting surface of the first optical path bending mirror 38 is formed on one inclined surface, and the reflecting surface of the second optical path bending mirror 42 is formed on the other inclined surface. When the base material is made of silicon carbide, the right-angle reflecting mirror 44 is formed by performing shaping after pouring silicon carbide into the mold.
The reflection surface of the first optical path bending mirror 38 and the reflection surface of the second optical path bending mirror 42 are metal reflection surfaces. The metal reflecting surface is a surface obtained by coating the slopes 45 and 46 of the base material with a material suitable for polishing, such as Si, by chemical vapor deposition (CVD) or the like, and mirror-polishing the slopes 45 and 46. Is coated with a metal film (such as an aluminum film) or a fluoride film. Further, a fluoride film may be formed on the metal film.
Furthermore, it is preferable that the material coating for providing a mirror surface such as Si is applied not only to the slopes 45 and 46 of the base material but also to the entire surface of the base material, for example, a support leg 44a of a right-angle reflecting mirror 44 described later. . By coating the entire surface of the base material in this way, volatilization of a light-absorbing substance (oxygen, water vapor, organic matter, etc. that absorbs exposure light EL) from the base material can be reduced. In addition, when coating a reflective surface and another part, since the reflective surface needs mirror surface processing, the one where it is thicker than another part is desirable. Further, as the processing accuracy of the base material, it is desirable that the squareness of both reflecting surfaces is within ± 5 seconds and the surface accuracy is within 3.5 to 7λ / 10000 rms. Further, the reflecting surface of the concave reflecting mirror 41 may be a metal reflecting surface as in the case of the right-angle reflecting mirror 44, and it is desirable that accuracy other than the squareness and other processing be performed in the same manner as the right-angle reflecting mirror 44.
In addition, both inclined surfaces 45 and 46 of the right-angle reflecting mirror 44 are optically isolated. Therefore, the light beam from the first imaging optical system 35 does not enter the second optical path bending mirror 42, and the light beam from the second imaging optical system 39 does not enter the first optical path bending mirror 38.
The horizontal lens barrel 33 includes a first holding frame 37 a that holds the concave reflecting mirror 41, a second holding frame 37 b that holds the negative lens 40, and a third holding frame 37 c that holds the right-angle reflecting mirror 44. The first holding frame 37a that holds the concave reflecting mirror 41 has a bottomed cylindrical shape.
The first holding frame 37a, the second holding frame 37b, and the third holding frame 37c are connected to each other. That is, the inner end of the first holding frame 37a and the outer end of the second holding frame 37b are connected, and the inner end of the second holding frame 37b and the outer end of the third holding frame 37c are connected. . Further, the second holding frame 37b is connected to the connecting member 31 at the inner end portion 33a. The outer shape of the inner end portion 33a of the second holding frame 37b is smaller than the outer diameter of the outer end portion. The horizontal barrel 33 is connected to the connecting member 31 in a state where the inner end portion 33 a is inserted into the connecting member 31. The inner end portion 33a functions as one end portion of the second holding member.
As shown in FIG. 3, the third holding frame 37c is formed in a bottomed quadrangular prism shape. At the bottom 48 of the third holding frame 37, the right-angle reflecting mirror 44 is held so that the ridge lines of both inclined surfaces 45 and 46 of the right-angle reflecting mirror 44 face the concave reflecting mirror 41. The right-angle reflecting mirror 44 has a support leg 44a formed at a position away from both reflection surfaces, and is held by the third holding frame 37c via the support leg 44a.
A guide rail 49 as a part of the optical element exchanging mechanism is formed on the bottom 48 of the third holding frame 37 c, and the support leg 44 a of the right-angle reflecting mirror 44 is formed with respect to the guide rail 49. It can move in a direction parallel to the ridgeline. An opening (not shown) is formed in the side wall of the third holding frame 37c on the extension line of the guide rail 49, and the right-angle reflecting mirror 44 can be exchanged through this opening. Since the third holding frame 37c is inserted into the connecting body 54, the connecting body 54 is also formed with a reflector replacement opening 67 as a part of the optical element replacement mechanism (for details, see FIG. Later).
On the side wall 51 a of the third holding frame 37 c facing the reflecting surface of the first optical path bending mirror 38 of the right-angle reflecting mirror 44, the exposure light EL that has passed through the first imaging optical system 35 is the first of the right-angle reflecting mirror 44. An opening 50a is formed having a dimension that does not cause the exposure light EL to be “scratched” when entering the reflecting surface of the optical path bending mirror 38. On the side wall 51b of the third holding frame 37c facing the reflecting surface of the second optical path folding mirror 42, the exposure light EL reflected by the reflecting surface of the second optical path folding mirror 42 of the right angle reflecting mirror 44 is the third imaging optical system. An opening 50b having a size such that the exposure light EL is not scattered when being deflected toward 43 is formed. The side wall 51a of the third holding frame 37c directly passes through the third imaging optical system 35 without passing through the first optical path folding mirror 38, the second imaging optical system 39, and the second optical path folding mirror 42. It functions as a shielding plate for shielding stray light incident on the system 43.
The lower barrel 34 is arranged on the first optical axis AX of the projection optical system 25, that is, on the side close to the wafer W on the same axis as the upper barrel 32. The lower barrel 34 has a substantially cylindrical shape, and a reduced image of the pattern on the reticle R (an image of the second intermediate image, which is the final image of the pattern), based on the light beam from the second intermediate image. ) Is formed on the wafer W. The third imaging optical system 43 is held. The third imaging optical system 43 has a plurality of refractive optical elements. The lower barrel 34 is formed by laminating a plurality (four in the present embodiment) of holding frames 37l each holding one or a plurality of lenses 36b and a cover glass 28 as third optical elements. Yes.
The upper end of the lower barrel 34, that is, the end 34a of the holding frame 37lr arranged on the side close to the reticle R has a smaller diameter than the outer diameter of the other holding frame 37l of the lower barrel 34. The end 34 a is inserted into the connecting member 31, and the lower barrel 34 is connected to the connecting member 31. This end 34a functions as one end of the third holding member. In order to avoid interference with the horizontal lens barrel 33 connected to the connecting member 31, a concave portion (a meat removal portion) 34 b is provided in a part of the end portion 34 a.
Next, the connecting member 31 will be described.
As shown in FIGS. 2 and 3, the connecting member 31 includes a connecting body 54 connected to the upper lens barrel 32, the horizontal lens barrel 33, and the lower lens barrel 34, and the connecting body 54 as a lower frame of the exposure apparatus main body 12. 14 and a flange 55 as an attachment member for attachment to the motor 14. The connecting body 54 and the flange 55 are made of ceramics such as silicon carbide, for example.
4 is a cross-sectional view of the upper barrel 32 taken along line 4-4 in FIG.
As shown in FIGS. 3 and 4, the connecting body 54 has a substantially octagonal prism shape. As shown in FIGS. 2 and 3, an upper lens barrel mounting recess 56 is formed on the upper surface of the coupling body 54 as a first coupling portion into which the end portion 32 a of the upper lens barrel 32 is inserted. On the lower surface of the connecting body 54, a lower barrel mounting recess 57 is formed as a third connecting portion into which the end 34a of the lower barrel 34 is inserted. The upper barrel attachment recess 56 and the lower barrel attachment recess 57 are formed so that the upper barrel 32 and the lower barrel 34 are arranged on the first optical axis AX. On one side of the connecting body 54, a horizontal barrel mounting hole 58 is formed in which the third holding frame 37c of the horizontal barrel 33 is inserted and the inner end 33a of the second holding frame 37b is inserted. ing. Fixing portions 54 b that are fixed to a plurality of (three in this embodiment) flanges 55 are formed on the outer peripheral side surface of the connecting body 54. A partition wall 59 that partitions the upper barrel mounting recess 56 and the lower barrel mounting recess 57 is formed with a notch 60 in which a horizontal barrel mounting hole 58 is continuous. The third holding frame 37c of the horizontal barrel 33 is accommodated in the notch 60.
The upper lens barrel 32 is connected to the upper lens barrel mounting recess 56, and the horizontal lens barrel 33 is connected to the horizontal lens barrel mounting hole 58, and fixed to the connecting body 54 by bolts 61. The fixing portion 54b of the connecting body 54 and one surface (upper surface) of the flange 55 are fixed by a bolt 62, and the connecting body 54 and the flange 55 are integrated. The flange 55 has a shape larger than the outer diameter in the plane orthogonal to the first optical axis AX of the coupling body 54, and has an opening 63 into which the lower barrel 34 can be inserted. The opening 63 is formed at a substantially central portion of the flange 55. The lower barrel 34 is inserted into the opening 63 of the flange 55, and the bolt mounting portion 65 formed on the holding frame 37 lr of the lower barrel 34 is fixed to the other surface (lower surface) of the flange 55 by the bolt 64.
Thus, the upper barrel 32, the horizontal barrel 33, and the lower barrel 34 are coupled to the coupling body 54 of the coupling member 31, and the upper barrel 32 and the horizontal barrel 33 are coupled to the coupling body 54, and the lower barrel. In a state where 34 is fixed to the flange 55, the lens barrels 32 to 34 do not contact each other.
The flange 55 is placed on the lower base 14 of the exposure apparatus main body 12 via a plurality of (for example, three) washers having a predetermined thickness arranged at a predetermined interval.
By the way, when the exposure light EL is irradiated to the lenses 36a and 36b and the cover glasses 27 and 28 of the projection optical system 25, the lenses 36a and 36b and the cover glasses 27 and 28 may generate heat. The heat of the lenses 36a and 36b and the cover glasses 27 and 28 is transmitted to the connecting body 54 and the flange 55 through the holding frames 37u, 37uw, 37a, 37b, 37c, 37lr, and 37l constituting the lens barrels 32 to 34. The
In the present embodiment, the lens barrels 32 to 34 are made of a metal material, whereas the coupling body 54 and the flange 55 are made of ceramics. For this reason, the linear expansion coefficient is different between the upper barrel 32 and the connecting body 54, and a difference occurs in the amount of thermal deformation. Further, the horizontal lens barrel 33 and the coupling body 54 have different linear expansion coefficients, resulting in a difference in the amount of thermal deformation. Furthermore, the lower lens barrel 34 and the flange 55 have different linear expansion coefficients, resulting in a difference in the amount of thermal deformation.
Therefore, as shown in FIGS. 4 and 5, a plurality of (three in this embodiment) bolt mounting portions 65 are formed at equal angular intervals on the outer peripheral surface of the holding frame 37 uw of the upper barrel 32. Yes. A pair of substantially Ω-shaped slits 66 is formed in the bolt mounting portion 65 so as to surround a bolt hole (not shown) formed in the center. A flexure structure is formed by the pair of slits 66. Due to the flexure structure, the upper barrel 32 includes a bolt 61 inserted into the bolt hole of the bolt mounting portion 65 and screwed into the screw hole 54a of the coupling body 54, and the bolt mounting portion 65 of the holding frame 37uw of the upper barrel 32. A minute relative movement in the radial direction is allowed. By this relative movement, the difference between the thermal deformation in the radial direction of the upper barrel 32 and the thermal deformation between the coupling body 54 is absorbed.
Bolt mounting portions 65 similar to the holding frame 37 uw of the upper barrel 32 are also formed on the outer circumferential surface of the second holding frame 37 b of the horizontal barrel 33 and on the outer circumferential surface of the holding frame 37 lr of the lower barrel 34. . Thus, the bolt 61 inserted into the bolt hole of the bolt mounting portion 65 and screwed into the screw hole 54a (see FIG. 3) of the connecting body 54, and the bolt mounting portion 65 of the second holding frame 37b of the horizontal barrel 33. A minute relative movement in the radial direction of the horizontal barrel 33 is allowed. And by this relative movement, the difference between the thermal deformation in the radial direction of the horizontal barrel 33 and the thermal deformation between the coupling body 54 is absorbed.
A bolt 64 inserted into a bolt hole of the bolt mounting portion 65 and screwed into a screw hole (not shown) of the flange 55, and a bolt mounting portion 65 of the holding frame 37lr of the lower barrel 34, the lower barrel 34 Minute relative movement in the radial direction is allowed. And by this relative movement, the difference between the thermal deformation in the radial direction of the lower barrel 34 and the thermal deformation between the flange 55 is absorbed.
As shown in FIG. 1, on one side surface corresponding to one end surface in the longitudinal direction of the right-angle reflecting mirror 44 in the coupling body 54, as a part of the optical element exchanging apparatus that allows the right-angle reflecting mirror 44 to pass. The reflector replacement opening 67 is formed so as to be continuous with the guide rail 49 of the third holding frame 37 c of the horizontal lens barrel 33. The reflector replacement opening 67 is always sealed with a plug 68 to ensure airtightness in the projection optical system 25. On the other hand, when the right-angle reflecting mirror 44 needs to be replaced, the plug 68 is removed and the right-angle reflecting mirror 44 is moved along the guide rail 49 to replace the right-angle reflecting mirror 44 from the reflecting mirror replacement opening 67. Do.
According to the first embodiment, the following advantages can be obtained.
(A) In the projection optical system 25, the upper barrel 32 holding the first imaging optical system 35 disposed on the first optical axis AX is coupled to the upper barrel mounting recess 56 of the coupling body 54. The lower barrel 34 that holds the third imaging optical system 43 disposed on the first optical axis AX is coupled to the lower barrel mounting recess 57 of the coupling body 54. The horizontal barrel 33 that holds the second imaging optical system 39 disposed on the second optical axis AX ′ is coupled to the lateral barrel mounting hole 58 of the coupling body 54. The lens barrels 32 to 34 are held on the lower gantry 14 of the exposure apparatus main body 12 via the coupling body 54 and the flange 55. For this reason, the upper barrel 32 and the horizontal barrel 33 having optical axes orthogonal to each other are connected to the connecting body 54 independently of each other. Further, the lower barrel 34 and the horizontal barrel 33 having optical axes orthogonal to each other are connected to the connecting body 54 independently of each other. The lens barrels 32 to 34 are supported by the lower mount 14 independently of each other via the connecting body 54 and the flange 55. Thereby, the weight of the other lens barrel does not act on the lens barrels 32 to 34 between the lens barrels 32 to 34, and the occurrence of distortion due to the uneven load is suppressed in each of the lens barrels 32 to 34. Accordingly, the surface states of the cover glasses 27 and 28, the lenses 36a and 36b, the first and second optical path bending mirrors 38 and 42, the negative lens 40, and the concave reflecting mirror 41 in the lens barrels 32 to 34 can be kept good. . The connecting member 31 has a simple configuration including a connecting body 54 and a flange 55. By providing the connecting member 31, the lens barrels 32 to 34 are made to cover glass 27 and 28 of the imaging optical systems 35, 39 and 43, lenses 36 a and 36 b, first and second optical path bending mirrors 38 and 42, and negative lenses. 40 and the concave reflecting mirror 41 can be held without deteriorating the surface accuracy.
Therefore, the imaging performance of the projection optical system 25 is improved, and the exposure accuracy can be improved. In addition, the configuration of the connecting member 31 is simple. By attaching the connecting member 31 to the projection optical system 25, the weight of the projection optical system 25 does not increase greatly, and the projection optical system 25 However, even if the size is increased and the weight is increased, it can be kept to a slight extent.
Also in the exposure apparatus main body 12, in order to directly support the horizontal lens barrel 33, it is not necessary to increase the size of the lower frame 14 of the exposure apparatus main body 12 or to separately provide a support device for supporting the horizontal lens barrel 33. . Therefore, the enlargement of the exposure apparatus main body 12 can also be suppressed.
The first imaging optical system 35 and the third imaging optical system 43 arranged on the first optical axis AX are divided and held in an upper lens barrel 32 and a lower lens barrel 34, respectively. The length of the cylinders 32 and 34 can be shortened. Since the distance from the support point to the tip of each barrel 32, 34 is shortened, the vibration of the projection optical system 25 is further reduced, and the resolution of the projection optical system 25 can be further improved.
(B) The projection optical system 25 includes a refraction-type first imaging optical system 35 and a third imaging optical system 43, and includes a concave reflecting mirror 41 between the imaging optical systems 35 and 43. An imaging optical system 39 is included. That is, the projection optical system 25 has an imaging point for each of the imaging optical systems 35, 43, and 39. Therefore, the aberration state can be adjusted for each of the imaging optical systems 35, 43, and 39. Further, since the first and third imaging optical systems 35 and 43 do not include the reflecting optical element such as the concave reflecting mirror 41, the lenses 36a and 36b held by the upper barrel 32 and the lower barrel 34 are used. And the arrangement direction of the cover glasses 27 and 28 can be aligned. Therefore, the structure of the upper lens barrel 32 and the lower lens barrel 34 can be simplified.
(C) In the projection optical system 25, the connecting body 54 is connected to the upper lens barrel 32 with the end 32 a of the upper lens barrel 32 inserted into the upper lens barrel mounting recess 56, and the inner end of the horizontal lens barrel 33. The portion 33a is connected to the horizontal barrel 33 in a state where the portion 33a is inserted into the horizontal barrel mounting hole 58 from a direction different from that of the upper barrel 32. Therefore, the upper lens barrel 32 and the horizontal lens barrel 33 can be coupled to the coupling body 54 from two directions with a simple configuration. In addition, by inserting the inner end portion 33a of the horizontal barrel 33 into the horizontal barrel mounting hole 58 of the connecting body 54, the horizontal barrel 33 can be easily positioned with respect to the upper barrel 32 and the lower barrel 34. Can do.
(D) In the projection optical system 25, the upper barrel 32 has holding frames 37u and 37uw for holding one or a combination of two or more optical elements (cover glass 27, lens 36a). Further, the horizontal barrel 33 has holding frames 37a to 37c for holding one or a combination of two or more optical elements (first and second optical path bending mirrors 38 and 42, negative lens 40 and concave reflecting mirror 41). are doing. Further, the lower barrel 34 has holding frames 37lr and 37l for holding one or a combination of two or more optical elements (lens 36b, cover glass 28). For this reason, the relative position of the optical element can be finely and precisely adjusted in each of the lens barrels 32 to 34. Thereby, aberration adjustment with higher accuracy becomes possible, and the resolution of the projection optical system 25 can be further improved.
(E) In the projection optical system 25, the guide rail 49 for exchanging the right-angle reflecting mirror 44 accommodated in the coupling body 54 while the horizontal barrel 33 and the coupling body 54 are held by the horizontal barrel 33, and A reflector replacement opening 67 is provided. For this reason, even if the reflecting mirror replacement opening 67 for replacing the right-angle reflecting mirror 44 is formed by forming the coupling body 54 from a material having sufficiently high rigidity, the strength of the lens barrels 32 to 34 is increased. No problems arise. Accordingly, the surface accuracy of each optical element (cover glasses 27 and 28, lenses 36a and 36b, first and second optical path bending mirrors 38 and 42, negative lens 40, and concave reflecting mirror 41) held by the lens barrels 32 to 34. Is kept good. Further, maintenance of the projection optical system 25 can be easily performed.
(F) In the projection optical system 25, the right-angle reflecting mirror 44 is mounted in a replaceable manner. The reflecting film formed on the right-angle reflecting mirror 44 as the optical path bending mirrors 38 and 42 is particularly F. ₂ When using exposure light EL having a very short wavelength, such as a laser or EUV, it is desirable to replace the exposure light after a predetermined period in order to keep the reflection performance stable. Therefore, such a projection optical system 25 is particularly suitable for the exposure apparatus 11 that uses far ultraviolet light to vacuum ultraviolet light as the exposure light EL.
(G) In the projection optical system 25, the coupling body 54 and the flange 55 that support the lens barrels 32 to 34 are made of a ceramic material. For this reason, while providing high rigidity to the coupling body 54 and the flange 55, the weight increase of the whole projection optical system by providing the coupling body 54 and the flange 55 can be suppressed small. Here, in particular, among the ceramic materials, when silicon carbide having excellent thermal conductivity is employed, the heat generated by the irradiation of the exposure light EL is transmitted through the lens barrels 32 to 34, the coupling body 54, and the flange 55. Thus, it is possible to quickly escape to the lower mount 14 of the exposure apparatus main body 12. Thereby, the surface state of the optical elements (cover glasses 27 and 28, lenses 36a and 36b, first and second optical path bending mirrors 38 and 42, negative lens 40 and concave reflecting mirror 41) during irradiation with the exposure light EL is good. Can be kept in.
(H) In the projection optical system 25, the lens barrels 32 to 34 are made of a metal material, and the coupling body 54 and the flange 55 are made of a ceramic material having a different linear expansion coefficient from the material of the lens barrels 32 to 34. And the flexure mechanism which consists of a pair of slit 66 is formed in the bolt attachment part 65 in each barrel 32-34. For this reason, thermal deformation of each of the lens barrels 32 to 34 accompanying irradiation of the exposure light EL can be absorbed by deformation of the bolt mounting portion 65. Therefore, the occurrence of distortion in each of the lens barrels 32 to 34 is suppressed, and the optical elements (cover glasses 27 and 28, lenses 36a and 36b, first and second optical path bending mirrors 38 and 42 during irradiation with the exposure light EL) are suppressed. The surface states of the negative lens 40 and the concave reflecting mirror 41) can be kept good.
(I) In the projection optical system 25, the connecting body 54 and the flange 55 are formed separately. For this reason, the side surface opposite to the horizontal barrel mounting hole 58 in the connecting body 54 is formed in a flat shape, so that the horizontal lens barrel 33 is connected to the connecting body 54 and the horizontal lens barrel 33 is temporarily moved to the first position. The two optical axes AX ′ can be arranged in a standing state in which they are oriented in the vertical direction. Then, the second imaging optical system 39 held in the horizontal lens barrel 33 can be adjusted in the state in which the horizontal lens barrel 33 is raised, and the adjustment work can be facilitated.
(J) In the projection optical system 25, if the holding frames 37u, 37uw, 37a-37c, 37lr, 37l of the lens barrels 32-34 are made of the same material in one lens barrel 32-34, It is possible to suppress the occurrence of variation in thermal deformation for each of the holding frames 37u, 37uw, 37a to 37c, 37lr, and 37l in each of the lens barrels 32 to 34 during irradiation with the exposure light EL. Therefore, the surface accuracy of the optical elements (cover glasses 27 and 28, lenses 36a and 36b, first and second optical path bending mirrors 38 and 42, negative lens 40 and concave reflecting mirror 41) during irradiation with the exposure light EL is further improved. Can be kept in.
The projection optical system and exposure apparatus according to the second embodiment of the present invention will be described with a focus on differences from the first embodiment.
As shown in FIG. 6, the projection optical system 81 of the second embodiment is different from that of the first embodiment in the configuration of the vertical barrel 82 and the connecting member 83 as the first holding member.
That is, in the projection optical system 81, the vertical lens barrel 82 is a single substantially cylindrical structure. A first imaging optical system 35 disposed on the first optical axis AX and a third imaging optical system 43 also disposed on the first optical axis AX are held in the vertical lens barrel 82. . On the side surface of the vertical barrel 82, a horizontal barrel accommodation hole 82a that allows the third holding frame 37c of the horizontal barrel 33 to be inserted is formed near the center of the longitudinal axis.
The connecting member 83 is integrally formed with a connecting portion 84 for connecting the vertical lens barrel 82 and the horizontal lens barrel 33 and a flange portion 85 as an attachment member for attaching the connecting portion 84 to the lower frame 14 of the exposure apparatus main body 12. Has been. The connecting member 83 is made of Invar (registered trademark), which is a metal material having a small linear expansion coefficient. The connecting member 83 has an octagonal columnar connecting portion 84 and is formed to have an outer dimension larger than the outer diameter of the vertical barrel 82 in a plane orthogonal to the first optical axis AX. A vertical lens barrel insertion hole 86 is formed as a connecting portion. Further, the connecting portion 84 is formed to have an outer dimension larger than the outer diameter of the horizontal barrel 33 in a plane orthogonal to the second optical axis AX ′, and the vertical barrel insertion hole 86 is formed at the center of one side surface thereof. A horizontal barrel mounting hole 58 as a second connecting portion is formed so as to be connected.
Whereas the vertical barrel 82 and the horizontal barrel 33 are formed of stainless steel, titanium alloy, or the like, the connecting member 83 is formed of invar. For this reason, the vertical barrel 82 and the connecting member 83 have different linear expansion coefficients, resulting in a difference in the amount of thermal deformation. Further, the horizontal barrel 33 and the connecting member 83 have different linear expansion coefficients, and a difference occurs in the amount of thermal deformation.
On the other hand, on the outer peripheral surface of the vertical barrel 82, a plurality of (three in this embodiment) bolt mounting portions 65 having a pair of slits 66 slightly above the center of the vertical barrel 82 are provided. They are formed at angular intervals. The vertical barrel 82 is attached so that the horizontal barrel accommodation hole 82 a corresponds to the horizontal barrel mounting hole 58 of the connecting member 83 in a state where the vertical barrel 82 is inserted into the vertical barrel insertion hole 86 of the connecting member 83. . In a state where the vertical lens barrel 82 is inserted through the connecting member 83, the bolt mounting portion 65 of the vertical lens barrel 82 is engaged with the upper surface of the connecting member 83, and the bolt mounting portion 65 is tightened with the bolt 61 with respect to the connecting member 83. Fix it. Thereby, the vertical barrel 82 and the connecting member 83 are connected via the flexure structure including the pair of slits 66.
Thereby, a minute relative movement in the radial direction of the vertical barrel 82 between the bolt 61 fixed to the connecting member 83 and the bolt mounting portion 65 of the vertical barrel 82 is allowed. The relative movement absorbs the difference between the thermal deformation in the radial direction of the vertical barrel 82 and the thermal deformation between the connecting member 83.
The inner end 33a of the second holding frame 37b of the horizontal barrel 33 is formed by inserting the third holding frame 37c of the horizontal barrel 33 into the horizontal barrel receiving hole 82a of the vertical barrel 82. It is inserted into the horizontal barrel mounting hole 58. In this state, a plurality of bolt mounting portions 65 formed on the outer peripheral surface of the second holding frame 37 b of the horizontal barrel 33 and having a pair of slits 66 engage with the side surfaces of the connecting member 83. Then, the bolt mounting portion 65 is fastened and fixed to the connecting member 83 by the bolt 61. Thereby, the horizontal barrel 33 and the connecting member 83 are connected via the flexure structure including the pair of slits 66.
Thereby, a minute relative movement in the radial direction of the horizontal barrel 33 between the bolt 61 fixed to the connecting member 83 and the bolt mounting portion 65 of the second holding frame 37b of the horizontal barrel 33 is allowed. By this relative movement, the difference between the thermal deformation in the radial direction of the horizontal barrel 33 and the thermal deformation between the connecting member 83 is absorbed.
When the horizontal barrel 33 is connected to the connecting member 83, the vertical barrel 82 and the horizontal barrel 33 are separated from each other and do not contact each other.
Therefore, according to the second embodiment, the following effects can be obtained.
(K) In the projection optical system 81, the vertical lens barrel 82 holding the first imaging optical system 35 and the third imaging optical system 43 disposed on the first optical axis AX is inserted through the connecting member 83. In a state of being inserted through the hole 86, the bolt mounting portion 65 and the upper surface of the connecting portion 84 are connected by engagement. Further, the horizontal barrel 33 holding the second imaging optical system 39 disposed on the second optical axis AX ′ orthogonal to the first optical axis AX is connected to the horizontal barrel mounting hole 58 of the connecting member 83. ing. Both lens barrels 82 and 33 are held on the lower gantry 14 of the exposure apparatus main body 12 via the flange portion 85 of the connecting member 83.
Therefore, the vertical lens barrel 82 and the horizontal lens barrel 33 having optical axes orthogonal to each other are connected to the connecting member 83 in an independent state, and are supported on the lower gantry 14 in an independent state. Accordingly, the weight of the other lens barrel does not act on one of the lens barrels 32 to 34 between the lens barrels 32 to 34, and the occurrence of distortion due to the uneven load is suppressed in the lens barrels 82 and 33. . Accordingly, the surface states of the cover glasses 27 and 28, the lenses 36a and 36b, the first and second optical path bending mirrors 38 and 42, the negative lens 40, and the concave reflecting mirror 41 in the lens barrels 82 and 33 can be kept good. . Thus, by providing the connecting member 83 having a simple configuration, the lens barrels 82 and 33 can hold the imaging optical systems 35, 39, and 43 in a good state. Therefore, the imaging performance of the projection optical system 81 is improved, and the exposure accuracy can be improved.
(L) In the projection optical system 81, the lens barrels 82 and 33 are made of a metal material such as stainless steel or titanium alloy having a relatively large linear expansion coefficient, and the connecting member 83 is compared with the material constituting the lens barrels 82 and 33. It is made of a metal material with a small coefficient of linear expansion. A flexure mechanism including a pair of slits 66 is formed on the bolt mounting portion 65 in each of the lens barrels 82 and 33. For this reason, the thermal deformation of the lens barrels 82 and 33 due to the exposure light EL irradiation can be absorbed by the deformation of the bolt mounting portion 65. Therefore, the occurrence of distortion in each of the lens barrels 82 and 33 is suppressed, and the optical elements (cover glass 27 and 28, lenses 36a and 36b, first and second optical path bending mirrors 38 and 42 during irradiation with the exposure light EL) are suppressed. The surface states of the negative lens 40 and the concave reflecting mirror 41) can be kept good.
(M) In the connecting member 83 of the projection optical system 81, a connecting portion 84 that connects the vertical lens barrel 82 and the horizontal lens barrel 33 and a flange portion 85 that engages with the lower frame 14 of the exposure apparatus main body 12 are integrally formed. ing. For this reason, even if the connecting member 83 is provided in order to hold the lens barrels 82 and 33 on the connection and the lower gantry 14, an increase in the number of parts can be minimized.
The above embodiment may be modified as follows.
In the first embodiment, the upper barrel 32 is fixed to the connecting body 54 and the lower barrel 34 is fixed to the flange 55. On the other hand, the upper barrel 32 and the lower barrel 34 may be fixed to the connecting body 54. Further, the connecting member 31 may be engaged with the lower base 14 of the exposure apparatus main body 12 so as to hang down, and the upper lens barrel 32 and the lower lens barrel 34 may be fixed to the connector 54. When the connecting member 31 is suspended, the flange 55 is arranged on the upper side and the connecting body 54 is arranged on the lower side. Therefore, the upper barrel 32 is fixed to the flange 55 and the lower barrel 34 is fixed to the connecting body 54. May be.
In the first embodiment, the upper barrel 32 is fixed to the connecting body 54, and the connecting body 54 is fixed to the flange 55. On the other hand, as shown in FIG. 7, for example, a flange as an attachment member is provided on the outer peripheral surface of the lower barrel 34, for example, on the outer peripheral surface of the holding frame 37lr or the like disposed at the end opposite to the wafer W. It is good also as a structure which forms the part 91 and fixes the connection body 54 on the flange part 91. FIG. When comprised in this way, the increase in a number of parts can be suppressed.
In this case, when the material of the holding frame 37lr of the lower barrel 34 and the coupling body 54 are different, the bolt mounting portion in the upper barrel 32 of the first embodiment is used as a fixing portion for the flange portion 91 of the coupling body 54, for example. It is desirable to provide a flexure structure such as that formed in 65.
In the first embodiment, the connecting body 54 and the flange 55 may be integrated. Moreover, in 2nd Embodiment, you may comprise the connection part 84 and the flange part 85 by another body. In the first embodiment and the second embodiment, the first optical path folding mirror 38 and the second optical path folding mirror 42 are configured by one member, but the first optical path folding mirror 38 and the second optical path folding mirror are configured. 42 may be configured independently of each other.
In each embodiment, the holding frames 37u, 37uw, 37b, 37lr, and 37l each hold one lens 36a and 36b (in combination with the cover glasses 27 and 28 depending on the location) or the negative lens 40, respectively. On the other hand, each holding frame 37u, 37uw, 37b, 37lr, 37l may hold a plurality of lenses 36a, 36b or a negative lens 40.
In each embodiment, the horizontal lens barrel 33 holds the second imaging optical system 39 disposed on the second optical axis AX ′ orthogonal to the first optical axis AX. On the other hand, an optical system arranged on the optical axis that obliquely intersects the first optical axis AX may be held in the horizontal barrel 33. In this case, at least one of the upper barrel 32, the horizontal barrel 33, and the lower barrel 34 may be obliquely coupled to the upper surface, side surface, or lower surface of the coupling body 54.
In each embodiment, the first imaging optical system 35 and the third imaging optical system 43 are arranged on the first optical axis AX. However, the third imaging optical system 43 is coaxial with the first optical axis AX. Instead, they may be arranged on a third optical axis that intersects the first optical axis AX (or the second optical axis AX ′) or is parallel to the first optical axis AX. In short, the lens barrels that respectively hold the optical systems arranged on a plurality of optical axes that intersect continuously are independently connected to the connecting member without contacting each other, and the exposure apparatus is connected via the connecting member. What is necessary is just to be supported by the lower mount frame 14 of the main body 12. In this case, the first optical path folding mirror 38 and the second optical path folding mirror 42 may be formed in separate reflective optical elements.
In the first and second embodiments, the right-angle reflecting mirror 44 is held by the horizontal lens barrel 33, but the right-angle reflecting mirror 44 may be separated from the horizontal lens barrel 33. In the example shown in FIG. 8, the attachment 100 provided with the right-angle reflecting mirror 44 at the tip thereof is detachably attached to the side wall of the coupling body 54. In this case, the right-angle reflecting mirror 44 is held by the connecting member 31. Since it is not necessary to remove the horizontal barrel 33 in order to replace the right-angle reflecting mirror 44, the right-angle reflecting mirror 44 can be easily replaced. The right-angle reflecting mirror 44 may be a separate member that can be detached from the attachment 100.
As the light source 21, F that supplies pulsed light having a wavelength of 157 nm is used. ₂ KrF excimer laser that supplies not only laser light but also light with a wavelength of 248 nm, ArF excimer laser that supplies light with a wavelength of 193 nm, and Ar that supplies light with a wavelength of 126 nm ₂ A laser 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 to ultraviolet light.
The present invention is not limited to an exposure apparatus for manufacturing micro devices such as semiconductor elements. That is, the present invention provides a circuit pattern from a mother reticle to a glass substrate, a silicon wafer or the like in order to manufacture a reticle or mask used in an optical exposure apparatus, EUV exposure apparatus, X-ray exposure apparatus, and electron beam exposure apparatus. It is also applicable to an exposure apparatus that transfers Here, in an exposure apparatus using DUV (deep ultraviolet) or VUV (vacuum ultraviolet) light, a transmission type reticle is generally used. As the reticle substrate, quartz glass, fluorine-doped quartz glass, meteorite, Magnesium fluoride or quartz is used. In proximity-type X-ray exposure apparatuses and electron beam exposure apparatuses, a reflective mask (stencil mask, membrane mask, etc.) is used, and a silicon wafer or the like is used as the mask substrate.
The present invention is applicable to an exposure apparatus other than an exposure apparatus used for manufacturing a semiconductor element. For example, an exposure apparatus used to manufacture a display including a liquid crystal display element (LCD) and the like to transfer a device pattern onto a glass plate, and an exposure apparatus used to manufacture a thin film magnetic head and transfer the device pattern onto a ceramic wafer. The present invention can also be applied to an exposure apparatus used for manufacturing an image sensor such as a CCD.
In the above embodiment, the case where the present invention is applied to a scanning stepper has been described. However, the mask pattern is transferred to the substrate in a state where the mask and the substrate are stationary, and the substrate is sequentially moved step by step. The present invention can also be applied to a type of exposure apparatus.
In the above embodiment, the projection magnification of the projection optical systems 25 and 81 is the reduction magnification. However, the projection magnification is not limited to the reduction, and may be the same magnification or the enlargement magnification. For example, when the projection magnification is set to an enlargement magnification, light is incident from the third imaging optical system 43 side, and a primary image of the mask or reticle R is formed by the third imaging optical system 43. A secondary image may be formed by the second imaging optical system 39, and a tertiary image (final image) may be formed on the substrate such as the wafer W by the first imaging optical system 35.
The exposure apparatus 11 of the present invention is manufactured as follows, for example. That is, optical elements such as a plurality of lenses 36a, 36b, 40, reflecting mirrors 41, 44, and cover glasses 27, 28 constituting the projection optical systems 25, 81 are held by the respective lens barrels 32-34, 82. The lens barrels 32 to 34 and 82 are connected by connecting members 31 and 83 and incorporated in the exposure apparatus main body 12 for optical adjustment. Then, a wafer stage 26 (including a reticle stage 24 in the case of a scan type exposure apparatus) made up of a number of mechanical parts is attached to the exposure apparatus main body 12 and connected to wiring. Next, a gas supply pipe for supplying a gas is connected to the optical path of the exposure light EL, and further comprehensive adjustment (electrical adjustment, operation check, etc.) is performed.
Components constituting the lens barrels 32 to 34 and 82 are assembled after removing impurities such as processing oil and metal substances by ultrasonic cleaning or the like. The exposure apparatus 11 is preferably manufactured in a clean room in which the temperature, humidity, and pressure are controlled and maintained at an appropriate clean level.
Fluorite was taken as an example of a glass material, but crystals such as quartz, lithium fluoride, magnesium fluoride, strontium fluoride, lithium-calcium-aluminum fluoride, and lithium-strontium-aluminum fluoride, zirconium-barium- Lanthanum-aluminum fluoride glass, quartz glass doped with fluorine, quartz glass doped with hydrogen in addition to fluorine, quartz glass containing OH groups, quartz glass containing OH groups in addition to fluorine, etc. The improved quartz may be used.
Next, an embodiment of a device manufacturing method using the above-described exposure apparatus 11 in a lithography process will be described.
FIG. 9 is a flowchart illustrating a manufacturing example of a device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, or the like). As shown in FIG. 9, first, in step S101 (design step), function / performance design (for example, circuit design of a semiconductor device) of a device (micro device) is performed, and pattern design for realizing the function is performed. Do. Subsequently, in step S102 (mask manufacturing step), a mask (reticle R, photomask, etc.) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S103 (substrate manufacturing step), a substrate (wafer W, glass plate, etc.) is manufactured using a material such as silicon or glass.
In step S104 (substrate processing step), as will be described later, an actual circuit or the like is formed on the substrate using the mask and substrate prepared in steps S101 to S103, as will be described later. 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) 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. The device after inspection is shipped.
FIG. 10 is a diagram showing an example of a detailed flow of step S104 of FIG. 9 in the case of a semiconductor device. In FIG. 10, in step S111 (oxidation step), the surface of the wafer W (substrate) 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 the post-processing step, first, a photosensitive agent such as a photoresist is applied to the wafer W in step S115 (resist formation step). Subsequently, in step S116 (exposure step), the circuit pattern of the reticle R is transferred onto the wafer W by the lithography system (exposure apparatus 11) 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 the pre-process and the post-process.
The exposure apparatus 11 described above is used in the exposure step (step S116), and the resolution can be improved by the exposure light EL in the vacuum ultraviolet region, so that the exposure amount can be controlled with high accuracy. Therefore, according to the above device manufacturing method, as a result, a highly integrated device having a minimum line width of about 0.1 μm can be produced with a high yield.

Claims (23)

In a projection optical system that projects an image of a pattern formed on a mask supported on a frame onto a predetermined surface,
A first holding member that holds at least one first optical element disposed on the first optical axis;
A second holding member that holds at least one second optical element disposed on a second optical axis that intersects the first optical axis;
A connecting member having a first connecting part connected to the first holding member and a second connecting part connected to the second holding member;
A projection optical system comprising: an attachment member for attaching the connecting member to the gantry. The projection optical according to claim 1, wherein the first holding member connected to the first connecting portion does not contact the second holding member connected to the second connecting portion. system. The first connecting portion is connected to one end portion of the first holding member, the second connecting portion is connected to one end portion of the second holding member, and the first holding member and the second holding portion are connected. In a state where the holding member is connected to the connecting member, the optical axis of the first optical element held by the first holding member and the optical axis of the second optical element held by the second holding member The projection optical system according to claim 1, wherein the directions are different from each other. The projection optical system according to any one of claims 1 to 3, wherein the mounting member is provided integrally with the connecting member. On the first optical axis, on an axis parallel to the first optical axis, or on an axis that intersects the first optical axis, with the coupling member being sandwiched with respect to the first holding member And a third holding member for holding at least one third optical element disposed on the connecting member, wherein the connecting member has a third connecting portion connected to the third holding member. The projection optical system according to any one of claims 1 to 4. 6. The third holding member is connected to the third connecting portion without the first holding member, the second holding member, and the third holding member being in contact with each other. The projection optical system described in 1. The projection optical system according to claim 5, wherein the attachment member is provided on the third holding member, and the connecting member is supported by the third holding member. The first holding member includes at least one holding frame that holds the at least one first optical element, and the second holding member holds the at least one second optical element and a concave reflecting mirror. The projection optical system according to claim 1, further comprising at least one holding frame. 9. The at least one first optical element constitutes a first imaging optical system, and the at least one second optical element and the concave reflecting mirror constitute a second imaging optical system. The projection optical system described in 1. The projection optical system according to claim 8, wherein the holding frame of the first holding member and the holding frame of the second holding member are made of the same material. A first imaging optical system having a plurality of optical elements including the at least one first optical element and forming a first intermediate image of the pattern;
A first optical path bending mirror disposed near the formation position of the first intermediate image and deflecting a light beam directed to the first intermediate image or a light beam from the first intermediate image;
A second image forming unit that includes the at least one second optical element and a concave reflecting mirror, and forms a second intermediate image in the vicinity of a position where the first intermediate image is formed using a light beam from the first intermediate image. Optical system,
A second optical path bending mirror disposed near the formation position of the second intermediate image and deflecting a light beam directed to the second intermediate image or a light beam from the second intermediate image; and the at least one third optical element; And a third image-forming optical system that forms a reduced image of the pattern on a substrate using a light beam from the second intermediate image. The projection optical system according to claim 7. The first holding member includes a plurality of holding frames that hold a plurality of optical elements including the at least one first optical element, and the second holding member includes the first optical path bending mirror and the at least one optical element. A plurality of holding frames for holding the second optical element, the concave reflecting mirror, and the second optical path bending mirror, wherein the third holding member includes the at least one third optical element. The projection optical system according to claim 11, further comprising a plurality of holding frames that hold the lens. The projection optical system according to claim 12, wherein the plurality of holding frames are made of the same material. The connecting member includes an optical element exchanging mechanism for exchanging at least one optical element held in at least one of the first, second and third holding members and accommodated in the connecting member. The projection optical system according to claim 1, comprising: a projection optical system according to claim 1. The second optical element includes a first optical path bending mirror that deflects a light beam from the first intermediate image formed by at least a part of the first optical element or a light beam toward the first intermediate image, and the second optical element. A reflection optical element having a second optical path bending mirror for deflecting a light beam from the second intermediate image formed by the element based on the first intermediate image or a light beam toward the second intermediate image, and replacing the optical element The projection optical system according to claim 14, wherein the mechanism is for exchanging the reflection optical element. The projection optical system according to claim 1, wherein the connecting member is made of a ceramic material. At least one of the first, second, and third holding members and the gantry is formed of a material having a linear expansion coefficient that is different from the linear expansion coefficient of the material constituting the connection member. The difference between the linear expansion coefficients is larger than a predetermined value, and the first, second and third holding members, at least one of the mounts, and the connecting member are connected via a flexure mechanism. The projection optical system according to any one of claims 1 to 16, wherein the projection optical system is any one of claims 1 to 16. An exposure apparatus for exposing an image of a pattern formed on a mask onto a substrate, comprising the projection optical system according to any one of claims 1 to 17. A device manufacturing method, comprising: a lithography step of performing exposure using the exposure apparatus according to claim 18. In an exposure apparatus that exposes an image of a pattern formed on a mask onto a substrate,
A frame,
A catadioptric projection optical system supported by the gantry, the projection optical system,
A first holding member for holding at least one first optical element disposed on the first optical axis;
A second holding member for holding at least one second optical element disposed on the second optical axis;
The first holding member and the second holding member so that the first optical axis and the second optical axis intersect, and the first holding member and the second holding member are separated from each other. A connecting member for connecting
An exposure apparatus comprising: a flange for supporting the projection optical system on the mount. 21. The exposure apparatus according to claim 20, wherein the first holding member and the second holding member are formed to be attachable to the connecting member independently of each other. 21. The reflective optical element according to claim 20, further comprising a reflective optical element that is accommodated in the coupling member and changes a direction of light incident on the projection optical system along the first optical axis to a direction of the second optical axis. Exposure device. The exposure apparatus according to claim 22, wherein the reflective optical element has an attachment removably attached to the connecting member.

Images