JP2011096720A - Holding device of optical element, aligner using the same, and manufacturing method of device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holding device of an optical element, reducing an eccentric shift of the optical element by an external force, also reducing variation in aberration, and providing high resolution. <P>SOLUTION: A holding device 10 of an optical element is equipped with: a first support member 2 which is annular and supports an optical element 1; a second support member 3 which is annular and is positioned on the outer diameter side of the first support member 2 to support the first support member 2; and a plurality of elastic members 4 which elastically deform and are positioned between the first support member 2 and the second support member 3. The elastic member 4 is a cylindrical member, and one end face of the cylindrical member is coupled to the first support member 2 in the optical axis direction of the optical element 1 while the other end face of the cylindrical member is coupled to the second support member 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical element holding apparatus, an exposure apparatus using the same, and a device manufacturing method.

  In a lithography process, which is a manufacturing process for semiconductor devices, liquid crystal display devices, and the like, an exposure apparatus uses a pattern of an original (reticle or mask) as a photosensitive substrate (a resist layer is formed on the surface) via a projection optical system. A transfer device to a wafer, a glass plate, or the like). For example, in a semiconductor exposure apparatus, an optical device for forming an image of a reticle pattern on a wafer is used, but a high resolving power is required to create a highly integrated circuit. For this reason, an optical apparatus for a semiconductor exposure apparatus needs to suppress optical aberrations to be small. Specifically, the characteristics of optical elements such as lenses and mirrors constituting the optical apparatus and characteristics regarding films are uniform. Performance, processing accuracy of the optical surface shape of the optical element, and assembly accuracy are required.

  Here, the holding member for holding the optical element used in the optical device is generally formed of a metal material, that is, a material different from the optical element. However, due to a change in the environmental temperature or the like, the optical element or the holding member may change in shape and the aberration may change. Therefore, in recent years, an optical element holding device that can obtain high resolution with low aberration by reducing the deformation of the lens surface due to changes in environmental temperature, and further distortion and the like that occur during assembly. Has been proposed. For example, Patent Document 1 discloses an optical element including an elastic member that is elastically deformable in a radial direction between a first support member that supports the optical element and a second support member that supports the first support member. A holding device is disclosed. The elastic member includes a leaf spring whose both ends are coupled to the first support member and whose central portion is coupled to the second support member. When the environmental temperature changes, the leaf spring undergoes bending deformation. Reduces undesirable deformation of the optical element.

JP 2001-343576 A

However, in the optical element holding apparatus as shown in Patent Document 1, when the second support member is pushed and deformed in the radial direction from the outer shape side, the optical element moves eccentrically. FIG. 6 is a plan view of the optical element holding device shown in Patent Document 1 as seen from the optical axis direction. The holding device 100 includes an optical element 111, a first support member 112, a second support member 113, and a first support member 112 and a second support member 113 that are 120 ° on the circumference. And three elastic members 114a, 114b, 114c arranged at intervals. Here, with an arbitrary point on the optical axis (z axis) as the origin, an xyz orthogonal coordinate system and an rθz cylindrical coordinate system in which the x axis is θ = 0 are set, and the elastic constant of each elastic member 114 Are the same, and the components of the elastic constant relating to the rθz coordinate system are assumed to be Kr, Kθ, and Kz, respectively. For example, as shown in FIG. 6, when an external force acts on the second support member 113, the second support member 113 contracts in the y direction and deforms into an elliptical shape as indicated by a broken line. At this time, the y-direction component Ky of the elastic constant of each elastic member 114 is Ky = Kr in the elastic member 114c, while the y-direction component Ky of the elastic constant of the elastic members 114a and 114b is expressed by the following equation. Is done.
Ky = Kr × sin 30 ° + Kθ × cos 30 °
= (1/2) Kr + ((√3) / 2) Kθ
Here, the sum of the y-direction components of the elastic constants of the two elastic members 114a and 114b located on the y-axis direction plus side is Kr + (√3) Kθ, and the elastic member 114c located on the y-axis direction minus side is added. It is larger than the y-direction component Kr. Each elastic member 114 has low elasticity in the radial direction. That is, since the holding device of Patent Document 1 is configured so that Kr << Kθ, the difference in the y-direction component of the elastic constant is very large between the positive side and the negative side of the y-axis. . Therefore, the deformation in the y-axis direction of each elastic member 114 due to the deformation of the second support member 113 becomes large at the elastic member 114c, and the first support member 112 moves eccentrically in the minus direction of the y-axis, Along with this, the optical element 111 also moves eccentrically in the negative direction of the y-axis. Such deformation of the optical element 111 adversely affects the optical performance of the optical system including the optical element holding device.

  The present invention has been made in view of such circumstances, and provides an optical element holding device that reduces the eccentric movement of the optical element due to an external force, has a small change in aberration, and provides high resolution. For the purpose.

  In order to solve the above-described problems, the present invention provides an annular first support member that supports an optical element, and an annular first support member that is positioned on the outer diameter side of the first support member and supports the first support member. 2 is a holding device for an optical element, and a plurality of elastic members capable of elastic deformation located between the first support member and the second support member, wherein the elastic member is a cylindrical member. And one end surface of the cylindrical member is coupled to the first support member in the optical axis direction of the optical element, and the other end surface of the cylindrical member is coupled to the second support member.

  According to the present invention, by adopting a cylindrical elastic member having the same elastic constant in each direction, the eccentric movement of the optical element due to the second support member receiving an external force is reduced, and the aberration change An optical element holding device that is small in size and can provide high resolution is provided.

It is a cross-sectional three-dimensional view of the holding device for the optical element according to the embodiment of the present invention. It is an expanded view of the holding | maintenance apparatus of the optical element shown in FIG. It is the cross-sectional solid view which expanded the periphery of the elastic member shown in FIG. It is the top view which looked at the holding | maintenance apparatus of the optical element of this invention from the optical axis direction. It is the schematic which shows the structure of the exposure apparatus which concerns on embodiment of this invention. It is the top view which looked at the holding device of the conventional optical element from the optical axis direction.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Optical element holding device)
First, the configuration of the optical element holding device according to the embodiment of the present invention will be described. FIG. 1 is a cross-sectional three-dimensional view (perspective view) of an optical element holding device according to an embodiment of the present invention. FIG. 2 is a development view of the optical element holding device. The holding device 10 includes an optical element 1, a first support member 2, a second support member 3, and three elastic members 4. The optical element 1 is an optical element formed by a lens or a mirror. In the present embodiment, the optical element 1 is a lens, and the material of the lens is preferably quartz glass or meteorite glass.

  The first support member 2 is an annular member that supports the optical element 1 on the inner diameter side. First, the first support member 2 has an L-shaped groove portion 21 whose bottom portion faces the center of the diameter so as to accommodate the outer diameter portion of the optical element 1 on the inner diameter side thereof. The groove portion 21 has three protrusion portions 22 which are convex portions of a square shape or a hemispheric shape protruding upward in the optical axis direction on the horizontal plane at substantially equal intervals in the circumferential direction. Moreover, the 1st supporting member 2 possesses three notch parts 23 which accommodate the elastic member 4 mentioned later on the outer diameter side at equal intervals in the circumferential direction. The number of protrusions 22 and notches 23 is three in the present embodiment in consideration of manufacturing efficiency and operational efficiency, but is not particularly limited. The material of the first support member 2 has a thermal expansion coefficient that approximates that of the material of the optical element 1. For example, when the material of the optical element 1 is quartz glass, the material of the first support member 2 is preferably a cordierite ceramic material made of nickel alloy, magnesium oxide, silicon oxide, or the like. Alternatively, the material of the first support member 2 is preferably a ceramic material such as alumina or silicon nitride, and further, Zero Joule (registered trademark) which is a low thermal expansion glass. On the other hand, when the material of the optical element 1 is meteorite glass, the material of the first support member 2 is a copper alloy such as brass, an alloy of iron such as 18-8 stainless steel, chromium and nickel, or aluminum. An alloy or the like containing as a main component is suitable.

  The second support member 3 is an annular member that supports the first support member 2 on the inner diameter side. The second support member 3 has, on its inner diameter side, an L-shaped groove portion 31 whose bottom portion faces the diameter center so as to accommodate the outer diameter portion of the first support member 2. The material of the second support member 3 is preferably a steel material such as stainless steel.

  The elastic member 4 is a cylindrical member that can be elastically deformed, and has a first coupling portion 41 coupled to the first support member 2 on one end surface of the cylinder, and a second end surface facing the coupling portion 41. And a second coupling portion 42 coupled to the flat portion of the groove portion 31 formed in the second support member 3. In this embodiment, the 1st coupling | bond part 41 is two flat parts which protruded toward the center part of the cylinder, while the 2nd coupling | bond part 42 protruded toward the outer side of the cylinder. It is a flat part. The dimensions of the cylindrical member depend on the shape and weight of the optical element 1 to be held. For example, if the diameter of the optical element 1 is about 40 mm, the diameter of the cylinder is about 10 mm, and the optical axis direction of the cylinder The height is preferably about 5 mm, and the thickness of the cylindrical wall surface is preferably about 1 to 2 mm. Further, the material of the cylindrical member is preferably a metal material for spring formed of stainless steel or the like, or a non-metallic material such as zirconium, but the material is particularly limited as long as the formed cylindrical member has elasticity. is not.

  Next, connection of each member which comprises the holding | maintenance apparatus 10 is demonstrated. 3 is a cross-sectional three-dimensional view (perspective view) in which the periphery of the elastic member 4 in FIG. 1 is enlarged. Hereinafter, the optical element 1 shall be arrange | positioned so that an optical axis direction may correspond with a gravitational direction. First, the optical element 1 is fixed to the first support member 2 by bringing the lower surface in the gravitational direction into point contact with the three protrusions 22 and adhering the outer periphery to the side surface of the groove 21. Next, the first support member 2 is connected to the second support member 3 while accommodating the elastic members 4 in the three cutout portions 23 respectively. At this time, each elastic member 4 is disposed such that the central axis of the cylinder is parallel to the central axis of the first support member 2. In this case, the direction of each central axis coincides with the optical axis direction, that is, the gravity direction. The elastic member 4 fastens the first and second coupling parts 41 and 42 to the first and second support members 2 and 3, respectively, by a method such as adhesion (not shown) or screwing. It is fixed by.

  Next, the operation and effect of the holding device 10 will be described. First, in this embodiment, the materials of the optical element 1 and the first support member 2 have coefficients of thermal expansion that are close to each other, and the optical element 1 has three protrusions 22 in the optical axis direction. It is supported. Therefore, even if expansion or contraction occurs with respect to the optical element 1 and the first support member 2 due to a change in environmental temperature, the optical element 1 becomes a shape change close to simple expansion or simple contraction, Changes in the surface shape that are harmful to optical performance can be suppressed. In addition, when the first support member 2 and the second support member 3 are formed of materials having different thermal expansion coefficients, different expansion or contraction may occur due to a change in environmental temperature. In this case, according to the present invention, the elastic member 4 can be deformed to absorb these thermal expansion differences.

  Furthermore, in this embodiment, when an external force is applied to the side surface of the second support member 3, the elastic member 4 is deformed, thereby suppressing the deformation of the optical element 1. Hereinafter, the deformation of each elastic member 4 will be described in comparison with the example described in the conventional problem. FIG. 4 is a plan view of the holding device 10 according to the present embodiment as viewed from the optical axis direction. Here, as in FIG. 6 described above, an xyz orthogonal coordinate system is set with an arbitrary point on the optical axis (z axis) as the origin. In addition, since each elastic member 4 (4a, 4b, 4c) of this embodiment is a cylindrical member, the elastic constant Kc with respect to deformation symmetrical to the plane including the central axis of the cylinder is equal to the central axis of the cylinder. The elastic constants of the elastic members 4 are considered to be the same. For example, as shown in FIG. 4, when an external force is applied to the second support member 3, the second support member 3 contracts in the y direction and deforms into an elliptical shape as indicated by a broken line. At this time, the y-direction component of the elastic constant of the elastic member 4c located on the negative side of the y-axis is Kc. On the other hand, the sum of the y direction components of the elastic constants of the two elastic members 4a and 4b located on the plus side of the y axis is 2 × Kc, which is larger than the minus side of the y axis. However, when it is assumed that the elastic constant Kc of the elastic member 4 is equal to the r-direction component Kr of the elastic constant of the elastic member 114 shown in FIG. The constant y-direction component is equal to Kc = Kr. On the other hand, the sum of the y-direction components of the elastic constant on the plus side of the y-axis is 2 × Kc = 2 × Kr in the present embodiment, whereas the conventional example is Kr + (√3) Kθ. Here, since the conventional example is configured to satisfy Kr << Kθ, 2 × Kr << Kr + (√3) Kθ. That is, in the holding device 10 of the present embodiment, the difference in the y-direction component of the elastic constant between the positive side and the negative side of the y-axis is very small as compared with the holding device 100 of the conventional example. Therefore, when the second support member 3 is deformed by receiving an external force in the y direction, the amount by which the optical element 1 is decentered can be very small.

  As described above, according to the optical element holding device 10 of the present invention, the eccentric movement of the optical element 1 due to the second holding member 3 receiving an external force in the radial direction can be reduced. Thereby, the change of the surface shape which is harmful to the optical performance of the optical element 1 can be suppressed.

(Exposure equipment)
Next, the configuration of an exposure apparatus to which the optical element holding device of the present invention is applied will be described. FIG. 5 is a schematic view showing the arrangement of an exposure apparatus to which the holding apparatus of the present invention is applied. The exposure apparatus 90 includes an illumination optical system 91, a reticle stage 92 that holds a reticle, a projection optical system 93, and a substrate stage 94 that holds a substrate to be processed. Note that the exposure apparatus 90 in the present embodiment employs a step-and-repeat method or a step-and-scan method, and exposes a pattern formed on the reticle onto a wafer that is a substrate to be processed. It is.

  The illumination optical system 91 is a device that includes a light source unit (not shown) and illuminates the reticle. In the light source unit, for example, a laser is used as the light source. Usable lasers include an ArF excimer laser having a wavelength of about 193 nm, a KrF excimer laser having a wavelength of about 248 nm, and an F2 excimer laser having a wavelength of about 157 nm. In addition, the kind of laser is not limited to an excimer laser, For example, a YAG laser may be used and the number of lasers is not limited. When a laser is used for the light source unit, it is preferable to use a light beam shaping optical system that shapes a parallel light beam from the laser light source into a desired beam shape and an incoherent optical system that makes a coherent laser incoherent. Furthermore, the light source that can be used in the light source unit is not limited to the laser, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can be used. The illumination optical system 91 includes a lens, a mirror, a light integrator, a diaphragm, and the like. In general, an optical system is arranged in the order of a condenser lens, a fly-eye lens, an aperture stop, a condenser lens, a slit, and an imaging optical system. The illumination optical system 91 can be used regardless of on-axis light or off-axis light. The light integrator includes an integrator configured by stacking a fly-eye lens and two sets of cylindrical lens array plates. The light integrator may be replaced with an optical rod or a diffraction element. The aperture stop is configured as a circular stop, an annular illumination stop for modified illumination, a quadrupole illumination stop, or the like.

  The reticle is, for example, a quartz glass original plate on which a circuit pattern to be transferred is formed. The reticle stage 92 is a stage that can move in the xy directions, and is a device that holds the reticle. Note that reticle stage 92 is held by reticle stage surface plate 95.

  The projection optical system 93 projects and exposes the pattern on the reticle illuminated with the exposure light from the illumination optical system 91 onto the substrate at a predetermined magnification (for example, 1/4). As the projection optical system 93, an optical system composed only of a plurality of optical elements or an optical system (catadioptric optical system) composed of a plurality of optical elements and at least one concave mirror can be employed. Alternatively, as the projection optical system 93, an optical system including a plurality of optical elements and at least one diffractive optical element such as a kinoform, an all-mirror optical system, or the like can be employed. The reticle stage surface plate 95 and the projection optical system 93 are supported on a floor surface (base surface) 96 by a lens barrel surface plate 98 via a damper 97. Here, the projection optical system 93 is indispensable for high resolution performance, and is required to have optical performance with extremely low aberration. Therefore, by applying the optical element holding device 10 described above, even if the projection optical system 93 is deformed by an external force or the like from the lens barrel surface plate 98, the optical performance is deteriorated due to the eccentric movement of the optical element. It becomes difficult to happen. That is, since optical performance with extremely low aberration can be obtained, it is possible to realize a lens system for obtaining the resolving power necessary for semiconductor manufacturing. The optical element holding device 10 of the present invention is applicable not only to the projection optical system 93 but also to the illumination optical system 91.

  A substrate (substrate to be processed) is an object to be processed such as a silicon wafer having a surface coated with a photosensitive agent (resist). The substrate stage 94 is a stage that can move in the xyz direction, and is a device that holds the substrate. The substrate stage 94 is installed on a stage surface plate 99 placed on a floor surface (base surface) 96.

  In the exposure apparatus 90 of the present embodiment, the diffracted light emitted from the reticle passes through the projection optical system 93 and is projected onto the substrate. The substrate and the reticle are in a conjugate relationship. In the case of a scanning projection exposure apparatus, the reticle pattern is transferred onto the substrate by scanning the reticle and the substrate. In the case of a stepper (step-and-repeat type exposure apparatus), exposure is performed with the reticle and substrate stationary.

(Device manufacturing method)
Next, a method for manufacturing a device (semiconductor device, liquid crystal display device, etc.) according to an embodiment of the present invention will be described. A semiconductor device is manufactured through a pre-process for producing an integrated circuit on a wafer and a post-process for completing an integrated circuit chip on the wafer produced in the pre-process as a product. The pre-process includes a step of exposing a wafer coated with a photosensitive agent using the above-described exposure apparatus, and a step of developing the wafer. The post-process includes an assembly process (dicing and bonding) and a packaging process (encapsulation). A liquid crystal display device is manufactured through a process of forming a transparent electrode. The step of forming the transparent electrode includes a step of applying a photosensitive agent to a glass substrate on which a transparent conductive film is deposited, a step of exposing the glass substrate on which the photosensitive agent is applied using the above-described exposure apparatus, and a glass substrate. The process of developing is included. According to the device manufacturing method of the present embodiment, it is possible to manufacture a higher quality device than before.

(Other embodiments)
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  In the above embodiment, as a method of connecting the elastic member 4 to the first and second support members 2 and 3, the first and second coupling portions 41 and 42 are formed on the elastic member 4 and bonded, or Although the method of fastening by screwing is adopted, the present invention is not limited to this. For example, the circumferential portions at both ends of the cylinder constituting the elastic member 4 may be directly bonded to the first and second support members 2 and 3. Alternatively, a hole having substantially the same diameter as that of the cylinder may be formed in the connection portion between the first and second support members 2 and 3, and both ends of the cylinder may be fitted into the hole.

DESCRIPTION OF SYMBOLS 1 Optical element 2 1st support member 3 2nd support member 4 Elastic member 10 Holding device 23 Notch part 31 Groove part 91 Illumination optical system 93 Projection optical system

Claims (6)

An annular first support member that supports the optical element, an annular second support member that is positioned on the outer diameter side of the first support member and supports the first support member, and the first An optical element holding device comprising a plurality of elastic members capable of elastic deformation located between a support member and the second support member,
The elastic member is a cylindrical member,
One end surface of the cylindrical member is coupled to the first support member in the optical axis direction of the optical element, and the other end surface of the cylindrical member is coupled to the second support member. Holding device for optical element. The first support member has a cutout portion for accommodating the elastic member,
The second support member has an L-shaped groove on the inner diameter side, with a bottom portion facing the diameter center,
The elastic member is coupled to the first support member while being accommodated in the cutout portion, and the other end surface of the cylindrical member is coupled to the flat portion of the groove portion. The holding device of the optical element described.   3. The optical element holding device according to claim 1, wherein the elastic member is disposed such that a central axis of a cylinder is parallel to a central axis of the first support member.   The optical element according to claim 1, wherein the elastic members are arranged at equal intervals in a circumferential direction of the first support member and the second support member. Holding device. An exposure apparatus having an illumination optical system that illuminates a pattern of an original and a projection optical system that guides light from the original to a substrate to be processed,
5. An exposure apparatus, wherein at least one of the illumination optical system and the projection optical system includes the optical element holding device according to any one of claims 1 to 4. Exposing the substrate using the exposure apparatus according to claim 5;
Developing the substrate;
A device manufacturing method characterized by comprising:

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