JP2014006360A - Optical member, optical device, exposure device, and method for manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical member that is advantageous to be supported in a stable planar shape.SOLUTION: An optical member 2 is supported via at least three portions. In particular, at least a first portion 2b nearest to the gravity center 2a of the optical member 2, in the three portions, is disposed outside the effective area of the optical member 2 and on a plane 2d continuing a neutral plane between an upper surface and a lower surface of the effective area.

Description

  The present invention relates to an optical member, an optical apparatus that supports the optical member, an exposure apparatus that uses the optical apparatus, and a device manufacturing method.

  An exposure apparatus is a lithography process included in a manufacturing process of a liquid crystal display device, a semiconductor device, etc., in which a pattern of an original (such as a mask) is transferred to a photosensitive substrate (glass having a resist layer formed on the surface) via a projection optical system. A device for transferring to a plate or wafer). In particular, an exposure apparatus for manufacturing a liquid crystal display device is required to be able to perform exposure processing on more substrates within a predetermined time. Therefore, the projection optical system in the exposure apparatus can be enlarged in order to widen the range that can be exposed at one time. Furthermore, this exposure apparatus is also required to improve resolution and overlay accuracy. Therefore, it is necessary to increase the size and accuracy of individual optical members included in the projection optical system. However, an increase in the size of the optical member may increase the surface shape error through support in the projection optical system due to an increase in the weight of the optical member and a decrease in relative rigidity. The same applies to the case of manufacturing an optical member. In particular, when a large optical member is manufactured, the surface shape of the optical member changes on a processing apparatus or a measuring instrument in repeated processing and measurement. Can do. Therefore, in order to suppress the deformation of the optical member due to the support of the optical member, Patent Document 1 discloses a support device that supports the outer peripheral portion of the optical member at at least three points arranged at equal intervals.

JP 2001-208945 A

  Here, for example, many reflection optical systems provided in an exposure apparatus for manufacturing a liquid crystal display device have an effective optical path outside the optical axis, so an optical member having a non-axisymmetric effective diameter (outer shape) is employed. It is common. If such a large optical member having a non-axisymmetric shape is supported by a plurality of support points that are simply distributed at equal intervals, a difference occurs in the load acting on each support point, which is not preferable in terms of optical performance. For example, when manufacturing such an optical member, if such a load difference occurs in the support device, an undesirable change may appear in the surface shape of the optical member. Also, in the process of manufacturing the exposure apparatus, various processes such as attachment / detachment of the optical member and surface shape correction / film formation are repeated. However, if the surface shape changes before and after the attachment / detachment of the optical member to / from the support portion, the exposure apparatus It is disadvantageous to achieve the necessary performance. The support device of Patent Document 1 supports the outer peripheral portion of the optical member at three equally spaced points, and is not suitable for supporting an optical member having a non-axisymmetric outer shape.

  The present invention has been made in view of such a situation, and an object thereof is to provide an optical member that is advantageous for supporting a stable surface shape, for example.

  In order to solve the above-mentioned problem, the present invention is an optical member supported via at least three locations, and at least a first location closest to the center of gravity of the optical member among the at least three locations is an optical member. It is characterized in that it is arranged on a surface continuous with a neutral plane between the upper surface and the lower surface of the effective region outside the effective region.

  According to the present invention, for example, an optical member that is advantageous for supporting a stable surface shape can be provided.

It is a figure which shows the structure of the optical apparatus which concerns on one Embodiment of this invention. It is a figure which shows the shape of the optical member which concerns on one Embodiment of this invention. It is a figure which shows the structure of the receiving member containing an elastic hinge. It is a figure which shows the structure of the exposure apparatus which concerns on one Embodiment of this invention.

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

(Optical member and optical device)
First, the structure of the optical member which concerns on one Embodiment of this invention, and the optical apparatus (support apparatus) which supports this optical member is demonstrated. FIG. 1 is a diagram illustrating a configuration of an optical device 1 according to the present embodiment. In particular, FIG. 1A is a perspective view of the entire optical device 1, and FIG. 1B is a side view seen from the X-axis direction. The optical device 1 uses, for example, a large optical member 2 that can be used in a projection optical system of an exposure apparatus used in a manufacturing process of a liquid crystal display device. In particular, in this embodiment, the optical member 2 is a lens or a mirror having a non-axisymmetric shape (effective diameter), and the material thereof is, for example, glass such as synthetic quartz. The shape of the optical member 2 will be described in detail below. Further, in each of the following drawings including FIG. 1, an X axis and a Y axis perpendicular to each other are taken in a plane in a state where the optical member 2 is supported, and perpendicular to the XY plane (in this embodiment, the direction of gravity). The Z axis is taken. First, the optical device 1 includes a frame 3, a plurality of members installed on the frame 3, a receiving member 4 that receives a specific position (surface) of the optical member 2, and a plurality of pressers that are installed to face the specific receiving member 4. And a plate 5.

  The frame 3 is a main body structure of the optical device 1. For example, as shown in FIG. 1, the frame 3 is larger than the surface area (planar outer shape) of the optical member 2 that is a support target and can withstand the weight of the optical member 2. It is comprised with the board | plate material which has fixed thickness. The material of the frame 3 is preferably a low thermal expansion material in order to reduce the influence of heat deformation on the optical member 2 due to heat from the outside, and for example, an Invar alloy can be adopted. However, when the influence of heat from the outside is small, the material of the frame 3 may be a general steel material. Furthermore, an opening 3 a having an opening area smaller than the surface area of the optical member 2 is formed inside the frame 3. This opening area is the surface area of the optical member 2 in order to increase the effective area of the optical member 2 when irradiated with exposure light, particularly when the optical device 1 is installed in the projection optical system of the exposure apparatus. It is desirable to be close.

  The receiving member 4 is installed in at least three locations of the frame 3 and places the optical member 2 in contact with the XY plane that is horizontal with respect to the direction of gravity of the optical member 2. In particular, in the present embodiment, as shown in FIG. 1, the outer shape of the optical member 2 is longer in the X-axis direction than in the Y-axis direction, and one side (first side) in the Y-axis direction is Most of the sides are composed of straight portions, and the other side (second side) has a non-axisymmetric shape that is mostly composed of curved portions. Therefore, in the present embodiment, in consideration of the shape of the optical member 2, the number of receiving members 4 is set to three, of which the first receiving member 4a is in the middle of the second side, while the second receiving member. 4b and the 3rd receiving member 4c shall be arrange | positioned in the front-end | tip vicinity of each 1st edge | side. The material of the receiving member 4 is, for example, a low friction coefficient material such as PTFE, and a lubricant may be further applied to reduce friction. The tip of each receiving member 4a, 4b, 4c that contacts the optical member 2 has a spherical shape, and the radius of this spherical shape is determined by the contact area determined from the material and physical properties in relation to the optical member 2. Specifically, the contact area may be set such that the eigenvalue is, for example, 100 Hz or more with reference to the eigenvalue. Furthermore, although attachment of the receiving member 4 to the frame 3 is assumed to be mechanical fastening using screws or the like in the present embodiment, for example, an adhesive or the like may be used. However, especially when the optical apparatus 1 is used in an exposure apparatus, the optical apparatus 1 is installed in the lens barrel (the lens barrel 16 in FIG. 4) of the projection optical system that becomes a closed space. At this time, if an adhesive is used, it may volatilize in the lens barrel and cause clouding in various optical elements. Therefore, it is desirable to adopt a low gas generation type as the adhesive.

  The pressing plate 5 is a plate material having elasticity, and is installed immediately above the two receiving members 4 including the second receiving member 4b and the third receiving member 4c. Thereby, the optical member 2 is pressed and fixed at the positions of the receiving members 4b and 4c. That is, in the first receiving member 4a other than these receiving members (other than the second receiving member 4b and the third receiving member 4c), the optical member 2 is not fixed and only receives its own weight. Furthermore, it is desirable to install a contact ball made of a low friction coefficient material at the contact portion of the pressing plate 5 with the optical member 2, similarly to the receiving member 4.

  Next, the shape of the optical member 2 will be described. FIG. 2 is a schematic diagram showing the shape of the optical member 2 mounted on the optical device 1 shown in FIG. 1. In particular, FIG. 2 (a) is a diagram showing the XY plane, and FIG. These are figures which show the AA 'cross section of Fig.2 (a). Since the plane of the optical member 2 is non-axisymmetric (asymmetric with respect to the optical axis), as shown in FIG. 2A, the XY plane from the center of gravity 2a to the three receiving members 4a, 4b, and 4c. Each distance above is different. This is because, in the position of the first receiving member 4a closest to the center of gravity 2a, the force in the Z-axis direction due to its own weight becomes the maximum, that is, the XY plane that can be generated at the portion where the optical member 2 and the receiving member 4 are in contact with each other. It means that the frictional force in the direction is maximized. Here, when manufacturing a large optical member with particularly high accuracy, a processing step such as polishing of an optical surface or correction aspherical processing and a measurement step mainly including surface measurement are repeatedly performed. Therefore, in the support device (optical device) included in the processing device or the measuring instrument, it is required that the surface shape of the optical member does not change before and after the optical member is attached or detached. Further, in the exposure apparatus, the optical member may be repeatedly attached / removed, re-formed, or corrected aspherical processing is performed in order to improve the imaging performance. Similarly, it is not preferable that the surface shape changes before and after the optical member is attached to and detached from the optical device in the exposure apparatus. Therefore, considering the point of improving the reproducibility of the surface shape of the optical member, it is most effective to dodge the stress at the position of the first receiving member 4a.

  Therefore, the optical member 2 of the present embodiment has a plurality of engraved portions (first engraved portion 2b and second engraved portion 2c) at a specific portion that contacts the receiving member 4 outside the effective region. As long as the engraved portion (also referred to as a supported location or simply a location) has a similar structure as a result, the formation method is not limited to so-called “engraving”. Among these, the 1st engraving part (1st location) 2b is a site | part which has a contact surface with the 1st receiving member 4a, On the other hand, the 2nd engraving part 2c is the 2nd receiving member 4b and the 3rd receiving member 4c. It is a site | part which has a contact surface with. Here, inside the thickness direction of the optical member 2, when frictional forces in the XY plane direction are generated in each receiving member 4, the upper surface (light incident surface) and the lower surface (light emitting surface) of the effective region of the optical member 2. There is a position (neutral surface 2d) where the expansion and contraction deformation is minimum (ideally zero). And the contact surface with the receiving member 4 of the 1st engraving part 2b and the 2nd engraving part 2c is set to the surface connected to the neutral surface 2d. Further, the neutral plane can be obtained by analyzing the structure of the effective region of the optical member 2 using, for example, a finite element method, although not limited thereto. Thereby, even if the frictional force generated on the contact surface with the receiving member 4 at each of the engraved portions 2b and 2c is different before and after the optical member 2 is attached and detached, the frictional force itself has an effect on the effective diameter of the optical member 2. Can be made smaller compared to the case where there are no engraved portions 2b and 2c. In addition, although it is desirable to install the engraved part corresponding to all the receiving members 4 as described above, the optical member 2 may have only the first engraved part 2b in terms of avoiding stress. Good. Furthermore, as described above, the force that may change before and after the optical member 2 is attached / detached is a frictional force at the three receiving positions, so the contact surfaces of the engraved portions 2b and 2c with the receiving members 4 are For example, it is desirable to have a polished finish. At this time, the centerline surface roughness (centerline average roughness) Ra is preferably 0.1 μm or less.

  As described above, the optical member 2 and the optical device 1 that supports the optical member 2 can reduce changes in the surface shape of the optical member 2 even when the optical member 2 has a large and non-axisymmetric shape. it can. In particular, when the optical member 2 is repeatedly attached to and detached from the optical device 1, it can be advantageous in improving the reproducibility of the surface shape of the optical member 2. In order to further reduce the frictional force that can be generated when the optical member 2 is attached or detached, a flexible elastic hinge (hinge member) may be formed on the receiving member 4 in a direction perpendicular to the direction of gravity rather than the direction of gravity. FIG. 3 is a cross-sectional view showing the configuration of the receiving member 4 including the elastic hinge 6. The elastic hinge 6 absorbs, for example, a force applied in the XY plane direction by deforming it into a specific state.

  As described above, according to the present embodiment, it is possible to provide an optical member that is advantageous for supporting a stable surface shape. Further, it is possible to provide an optical device that is advantageous for supporting the optical member with a stable surface shape.

(Exposure equipment)
Next, the configuration of an exposure apparatus according to an embodiment of the present invention will be described. FIG. 4 is a schematic view showing a configuration of the exposure apparatus 10 according to the present embodiment. As an example, this exposure apparatus 10 is used in the manufacture of a liquid crystal display device, and scan-type exposure that exposes a pattern formed on a mask (original plate) 11 on a glass plate (substrate) 12 by a step-and-scan method. A device. First, the exposure apparatus 10 includes an illumination system 13, an alignment scope 14, a mask stage (not shown) that holds the mask 11, a projection optical system 15, and a glass plate 12 that is coated with a photosensitive agent (not shown). A substrate stage. The illumination system 13 has a light source such as an Hg lamp, for example, and irradiates the mask 11 with illumination light shaped like a slit to project a pattern image onto the glass plate 12 via the projection optical system 15. . The alignment scope 14 observes positioning alignment marks formed on the mask and the glass plate. Here, when the illumination system 13 irradiates the mask 11 with illumination light, the alignment scope 14 has a configuration capable of driving part or all of the illumination scope 13 so as not to block the illumination light. Retraction driving can be performed outside the illumination light beam. The projection optical system 15 is installed in the lens barrel 16 and projects a pattern image onto the glass plate 12 held on the substrate stage. The projection optical system 15 includes two flat transmission elements 20, two plane mirrors 21, a concave mirror 22, and a convex mirror 23. The flat plate transmissive element 20 is disposed on the incident side and the outgoing side of the projection optical system 15 and is an optical element (optical member) for assisting in improving the imaging performance of the parallel flat glass or the projection optical system 15. . The plane mirror 21, the concave mirror 22, and the convex mirror 23 are optical members that reflect the pattern image, and the material thereof is glass having a small linear expansion coefficient. When the projection magnification of the projection optical system 15 is the same magnification, the exposure apparatus 10 performs scanning exposure by synchronizing the mask 11 and the glass plate 12 so that the pattern image from the mask 11 is formed on the glass plate 12 (substrate). The above can be transferred. In particular, in the exposure apparatus 10, the optical member 2 according to the above-described embodiment is adopted as the flat plate transmissive element 20, and although not shown, as a support portion for the flat plate transmissive element 20 included in the lens barrel 16. The optical device 1 according to the above embodiment can be employed. According to this, for example, when the flat transmissive element 20 is incorporated in the projection optical system 15, the surface shape of the flat transmissive element 20 is suitably reproduced even if the flat transmissive element 20 is repeatedly attached and detached. Therefore, it is possible to manufacture an exposure apparatus with higher accuracy than before.

(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.

  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.

2 Optical member 2a Center of gravity 2b First engraving portion 2d Internal surface 4a First receiving member

Claims (8)

An optical member supported through at least three locations,
A first location closest to the center of gravity of the optical member among the at least three locations is arranged outside the effective region of the optical member on a surface continuous with a neutral surface between the upper surface and the lower surface of the effective region. Being
An optical member.   The optical member according to claim 1, wherein the effective region is asymmetric with respect to an optical axis. At least one of the at least three locations has a centerline surface roughness of 0.1 μm or less,
The optical member according to claim 1, wherein the optical member is an optical member. The optical member according to any one of claims 1 to 3,
Frame,
At least three receiving members provided on the frame and receiving the optical member;
A plurality of pressing members that are provided facing each of a plurality of receiving members excluding the receiving member that receives the first portion of the optical member among the at least three receiving members, and that hold the optical member;
An optical device comprising:   The optical apparatus according to claim 4, wherein the receiving member includes a hinge member that is more flexible in a direction perpendicular to gravity than in a direction of gravity. An exposure apparatus for exposing a substrate,
It has an optical member given in any 1 paragraph of Claims 1 thru / or 3,
Exposing the substrate through the optical member;
An exposure apparatus characterized by that. An exposure apparatus for exposing a substrate,
An optical device according to claim 4 or 5,
Exposing the substrate through the optical device;
An exposure apparatus characterized by that. Exposing the substrate using the exposure apparatus according to claim 6 or 7,
Developing the substrate exposed in the step;
A device manufacturing method comprising:

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