JP2006140366A - Projection optical system and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To support an optical member constituting a projection optical system through a relatively simple and lightweight mechanism under a state ensuring high vibration removing performance. <P>SOLUTION: A concave mirror 24 out of a plurality of optical members constituting a projection optical system is contained in a lens frame 27 which is then suspended from an upper frame through three wires 30A-30C and three anti-vibration pads 31A-31C. The lens frame 27 is held at a target position for that frame by using three noncontact Z-axis actuators 33A, 33B, and the like, arranged on the bottom face of the lens frame 27 and three noncontact XY-axis actuators 32A, 32B and 32C arranged on the side face of the lens frame 27. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projection optical system that projects an image of a predetermined pattern. Furthermore, the present invention relates to an exposure apparatus used for transferring a mask pattern onto a substrate via a projection optical system when manufacturing various devices such as a semiconductor device, an image sensor (CCD, etc.), or a liquid crystal display. About.

  For example, in a lithography process, which is one of the manufacturing processes of a semiconductor device, a wafer (or glass plate) coated with a resist as a substrate (sensitive substrate) on a pattern (or a photomask) as a mask. Etc.) An exposure apparatus is used for the above-mentioned transfer exposure. As the exposure apparatus, a batch exposure type projection exposure apparatus such as a stepper or a scanning exposure type projection exposure apparatus (scanning exposure apparatus) such as a scanning stepper is used.

  In these exposure apparatuses, the rigidity of mechanical parts such as a stage for positioning and moving a reticle and wafer, a support mechanism for the stage, and a support mechanism for the projection optical system are used for vibration isolation performance and exposure accuracy (such as overlay accuracy). Greatly affects the performance of the apparatus, the weight of the mechanism, and the manufacturing cost of the exposure apparatus. In general, an exposure apparatus having a highly rigid mechanism part tends to increase the manufacturing cost because the apparatus performance is high while the weight of the mechanism part increases. The rigidity of the mechanism is also related to the stability of the device performance corresponding to the change of the device performance over time and the temperature characteristic of the device performance. That is, an exposure apparatus with a high rigidity of the mechanism portion tends to have high stability of the apparatus performance and excellent temperature characteristics, but depending on the structure of the mechanism section, the opposite behavior may be exhibited. For example, when high rigidity members are connected to each other via a high rigidity member in the mechanical part, vibration is easily transmitted, or a temperature characteristic is deteriorated due to a bimetal effect at the time of temperature change. There are things to do.

Further, as a result of increasing the rigidity of the mechanism portion, if the weight of the mechanism portion increases, there is a risk of increasing the construction cost of the device manufacturing factory where the exposure apparatus is installed. Therefore, conventionally, as a configuration for reducing the weight of the mechanism part as a whole while maintaining high rigidity at necessary portions, a parallel link mechanism having a plurality of rods each capable of expanding and contracting the base of the reticle stage and the wafer stage, etc. There has been proposed an exposure apparatus that supports them independently of each other (see, for example, Patent Document 1).
International Publication No. 01/022480 Pamphlet

As described above, in the conventional exposure apparatus, in order to maintain high apparatus performance such as vibration isolation performance, it is required to increase the rigidity of the mechanism section such as the support mechanism while reducing the weight of the mechanism section. .
Recently, in order to further improve the resolution, an exposure apparatus using EUV (Extreme Ultraviolet) light, which is extreme ultraviolet light having a wavelength of about 1 to 100 nm, has been developed as an exposure beam. A projection optical system used in such an exposure apparatus using EUV light is configured by arranging a plurality of mirrors such as concave mirrors in a predetermined positional relationship. However, if a conventional parallel link mechanism having a plurality of extendable rods is used to support such a plurality of mirrors, the structure of the support mechanism may become complicated and the weight may increase. Further, in an exposure apparatus that uses EUV light, it is necessary to increase the vibration isolation performance of the projection optical system, particularly in response to high resolution.

  Also, with recent exposure equipment, the amount of change in the imaging characteristics of the projection optical system and the amount of thermal deformation of the mechanism are predicted according to the ambient temperature and the exposure amount of the exposure beam, and image formation is performed in an online process according to this prediction result. Correction of characteristics, position correction of the reticle and wafer, and the like are also performed. Such predictive control is desirably applied also when a projection optical system including a plurality of mirrors is used. However, if the support mechanism of each mirror is complicated, the prediction accuracy of the variation amount of the imaging characteristics and the like may be reduced, and the exposure accuracy may be reduced.

In view of the above, it is a first object of the present invention to provide a technique capable of supporting an optical member constituting a projection optical system with a simple and lightweight mechanism in a state where high vibration isolation performance is obtained. .
A second object of the present invention is to provide an exposure technique capable of obtaining high apparatus performance by using a projection optical system having a simple and lightweight structure.

The projection optical system according to the present invention is a projection optical system that projects an image of a pattern, and includes a plurality of optical members (24, 25, 26) for guiding a beam from the pattern to an image plane, and at least of the plurality of optical members. It is provided with connecting members (30A, 31A) that suspend and support one optical member (24).
According to the present invention, at least one optical member constituting the projection optical system is supported so as to be suspended from a predetermined member via the connecting member in the vertical direction. Therefore, for example, the optical member is supported by a mechanism that is simpler and lighter than a support mechanism in which members having high rigidity are combined. In addition, vibration from the member supporting the connecting member is difficult to be transmitted to the optical member, and the natural frequency of the connecting member is low in at least the direction (horizontal direction) perpendicular to the hanging direction. Performance is obtained.

  In this case, the member that supports the connecting member and the optical member can be regarded as a rigid structure having high rigidity, and the connecting member can be regarded as a flexible structure having low rigidity. According to the present invention, the ratio of the rigid structure member in the optical system is reduced, and a flexible structure is incorporated. In the present invention, it is possible to use a rigid structure in a part that directly affects the performance of the apparatus, and use a flexible structure in a part that should block the effects of vibration transmission and thermal displacement, or a part that joins rigid structures. Therefore, the mechanism can be reduced in weight while maintaining high device performance such as vibration isolation performance.

In the present invention, as an example, the plurality of optical members are arranged in a vacuum atmosphere, and the connecting member includes a support device (31A) that supports the at least one optical member using atmospheric pressure. By using atmospheric pressure in this way, vibration and heat transfer can be suppressed.
In this case, as an example, the support device includes a cylinder part (41) to which the atmospheric pressure is supplied, and a piston that is levitated and supported in the cylinder part by the atmospheric pressure and connected to the at least one optical member. Part (42) and the exhaust part (45A, 45B) which keeps the surrounding part which surrounds the cylinder part in a vacuum atmosphere.

The connecting member may suspend and support the at least one optical member in the projection optical system. Thereby, the projection optical system can be assembled and adjusted independently of other mechanisms.
Moreover, as an example, the connecting member includes three wire members (30A to 30C) or rod members for each optical member supported by being suspended.

As another example, the connecting member includes three wire members (30A to 30C) or three rod members. Accordingly, each optical member or at least one optical member thereof can be stably supported.
In the present invention, the connecting member may include a damping mechanism (31A) that attenuates vibration of the at least one optical member. This improves the vibration isolation performance of the optical member.

In this case, as an example, the damping mechanism includes a cylinder part (41) to which a gas is supplied, and an optical member that is housed in the cylinder part and supported by being floated and supported by the gas. A piston part (42) to be connected and a pipe (45A, 45B) for exhausting gas leaking from the cylinder part are provided.
Moreover, as an example, the optical member supported by being suspended is a mirror (reflecting member) that reflects the beam. Mirrors such as concave mirrors, convex mirrors, and plane mirrors may be easier to suspend and support than transmissive members such as lenses.

Also, a frame mechanism (22) for supporting the connecting member, and displacement sensors (50A to 50C, 27a to 27c) for measuring displacements of the optical members supported by being suspended with respect to the frame mechanism with six degrees of freedom. And may further be provided.
In the present invention, since the connecting member has a flexible structure, the frame mechanism, which is a rigid structure, and the corresponding optical member may be relatively displaced at a low frequency. Therefore, by detecting the relative displacement with the displacement sensor and performing projection when the detection result is within the allowable range, for example, the influence of the relative displacement can be reduced.

In this case, as an example, the displacement sensor includes three movable mirrors (27a to 27c) provided on the optical member to be measured, a reference mirror (38A, 38B) provided on the frame mechanism, and the three movements. And an interferometer unit (35, 39A, 39B) for detecting a displacement of two degrees of freedom with respect to the reference mirror of the mirror.
Moreover, you may further provide the position adjustment mechanism (32A-32C, 33A-33C) which positions each optical member supported by hanging with respect to the frame mechanism by 6 degrees of freedom, respectively. By maintaining the relative position between the frame mechanism and each optical member at the target position using the position adjustment mechanism, the favorable characteristics (weight reduction of the mechanism and vibration and heat interruption) are maintained. However, it is possible to improve the apparatus performance such as the stability of the position of the projected image.

The frame mechanism may be formed of a material having a low expansion coefficient. This improves the stability of the imaging characteristics of the projection optical system.
Next, an exposure apparatus according to the present invention is an exposure apparatus provided with the projection optical system of the present invention, and transfers an image of the pattern onto the substrate (W) by the projection optical system. Since the projection optical system of the present invention has a simple and lightweight configuration and excellent vibration isolation performance, apparatus performance such as exposure accuracy is improved.

  In this case, as an example, the beam is extreme ultraviolet light having a wavelength of 1 to 100 nm, and the plurality of optical members constituting the projection optical system are mirrors. The projection optical system is configured by arranging a plurality of mirrors such as a concave mirror, a convex mirror, and a plane mirror in a predetermined positional relationship, and by supporting each mirror by hanging it, the support mechanism can be reduced in weight, Fine adjustment of the positional relationship of the mirrors and control of the imaging characteristics can be easily performed.

According to the present invention, since the optical member in the projection optical system is suspended and supported, the optical member in the projection optical system is supported by a simple and lightweight mechanism in a state where high vibration isolation performance is obtained. be able to.
Further, by suspending and supporting an optical member as a rigid structure via a connecting member as a flexible structure, it is possible to combine the rigid structure and the flexible structure by utilizing their respective advantages. Therefore, since the ratio occupied by the rigid structure can be reduced, the mechanism portion can be reduced in weight and cost without deteriorating the apparatus performance such as the vibration isolation performance and the stability of the position of the projected image.

Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to the drawings. In this example, EUV (Extreme Ultraviolet) light, which is extreme ultraviolet light having a wavelength of about 1 to 100 nm, is used as an exposure beam (energy beam), and an exposure apparatus (EUV exposure apparatus) having a reflective projection optical system ) To which the present invention is applied.
FIG. 1 is a cross-sectional view showing a schematic configuration of the exposure apparatus of this example. In FIG. 1, the exposure apparatus is housed in a vacuum chamber, but the chamber is omitted. ing. In FIG. 1, a wavelength selected from soft X-rays emitted from an EUV light source (not shown) such as a SOR (Synchrotron Orbital Radiation) ring device or a laser plasma light source is used as an exposure beam. EUV light such as 5 nm is used. Since the exposure beam IL made of the EUV light is reflected and propagated by a number of mirrors (reflecting members) such as a concave mirror, a convex mirror, or a plane mirror, a multi-layer for reflecting the EUV light is reflected on the reflecting surface of each mirror. A reflective film is formed.

  The exposure beam IL is first reflected by the plane mirror 1 and enters the reflective illumination optical system 2. The illumination optical system 2 includes a beam shaping optical system, an illuminance distribution uniforming optical system, an aperture stop, a field stop, a relay optical system, and the like. The exposure beam IL emitted from the illumination optical system 2 illuminates the illumination area of a predetermined shape (for example, an elongated rectangle) on the pattern surface (reflection surface) of the mask M on which the circuit pattern to be transferred is formed with a uniform illuminance distribution. . The exposure beam IL reflected by the pattern surface of the mask M has a plurality of concave mirrors 24, 25, and 26 as a plurality of optical members in the reflection type projection optical system PL having a projection magnification β of a reduction magnification (for example, ¼). It is reflected by the (mirror) and irradiated onto the exposure surface of the wafer W coated with an X-ray resist as a substrate (sensitive substrate). In FIG. 1, the projection optical system PL includes three concave mirrors 24 to 26. However, a convex mirror or a plane mirror may be used as the mirror (reflecting member), and the number thereof is three or more. Also good.

  Of the circuit pattern area formed on the mask M, the image of the portion illuminated by the exposure beam IL is imaged and projected onto one shot area on the wafer W via the projection optical system PL. The mask M and the wafer W can also be regarded as a first object and a second object, respectively. In this example, the pattern surface of the mask M and the exposure surface of the wafer W are substantially parallel to the horizontal plane and are directed downward along the vertical lines. In the following description, the Z-axis is taken along the direction of the vertical line, the X-axis is taken in a direction parallel to the paper surface of FIG. To do. The concave mirrors 24 to 26 of the projection optical system PL are sequentially arranged in an upward direction (+ Z direction), a downward direction (−Z direction), and an upward direction along a direction (X direction) parallel to the X axis. The concave mirrors 24 to 26 are arranged with their axes off in the X direction. In this configuration, an image in the illumination area that is elongated in the Y direction (non-scanning direction) on the pattern surface of the mask M is projected onto the wafer W, so that the entire circuit pattern of the mask M is captured on one shot on the wafer W. In order to transfer to the region, it is necessary to scan the mask M and the wafer W in the X direction (scanning direction) using the projection magnification β of the projection optical system PL as a speed ratio.

  Next, the stage system of this example will be described. First, the mask M disposed on the object plane side of the projection optical system PL is held on the mask stage 3 by electrostatic adsorption or the like. The mask stage 3 is connected to the guide 4 so as to be able to finely move in the X direction, the Y direction, and the rotation direction around the Z axis, and the guide 4 can move to the pair of X axis guides 5 in the X direction at a constant speed. So that they are connected. The mask stage 3 and the guide 4 smoothly slide in a non-contact state with respect to the guide surface via a magnetic bearing or the like. The movement coordinate position of the mask stage 3 (X-direction, Y-direction position, and rotation angle around the Z-axis) is on a movable mirror (not shown) fixed to the mask stage 3 and the upper side surface of the projection optical system PL. Measurement is sequentially performed by a mask-side interferometer system including a fixed reference mirror 9M, a beam splitter 8M that divides a laser beam, and a laser interferometer 7M. The mask interferometer system actually constitutes a triaxial laser interferometer having at least two axes in the X direction and one axis in the Y direction.

Measurement information of the mask-side interferometer system is supplied to a stage control system 11. The stage control system 11 controls the measurement information and control information (input information) from a main control system 10 comprising a computer that controls the overall operation of the apparatus. The operation of the mask stage 3 is controlled via a drive system (not shown) composed of a linear motor, a fine actuator, and the like.
On the other hand, the wafer W arranged on the image plane side of the projection optical system PL is held on the wafer stage 13 by electrostatic adsorption or the like. The wafer stage 13 is coupled to the guide 14 so that it can be stepped in the Y direction. The guide 14 can be moved to the pair of X-axis guides 15 at a constant speed in the X direction, and in the X direction as necessary. It is connected so that it can be moved step by step. The wafer stage 13 and the guide 14 slide smoothly in a non-contact state with respect to the guide surface via a magnetic bearing or the like. The movement coordinate position of the wafer stage 13 (X-direction, Y-direction position and rotation angle around the Z-axis) is fixed to the reference mirror 9W fixed to the upper side surface of the projection optical system PL and the wafer stage 13. Measurement is sequentially performed by a wafer-side interferometer system including a movable mirror (not shown), a beam splitter 8W that splits a laser beam, and a laser interferometer 7W. The wafer side interferometer system actually constitutes a triaxial laser interferometer having at least two axes in the X direction and one axis in the Y direction.

  Measurement information of the wafer-side interferometer system is supplied to a stage control system 11, and the stage control system 11 is composed of a linear motor, a fine actuator, etc. based on the measurement information and control information (input information) from the main control system 10. The operation of the wafer stage 13 is controlled via a drive system (not shown). Further, the wafer stage 13 has a Z leveling mechanism for controlling the position (focus position) of the wafer W in the Z direction and the tilt angles around the X axis and the Y axis based on the measurement result of an auto focus sensor (not shown). Is also provided.

  The stage control system 11 optimizes the wafer stage 13 based on the mask-side control circuit that optimally controls the mask stage 3 based on the measurement information obtained from the mask-side interferometer system, and the measurement information obtained from the wafer-side interferometer system. And a wafer side control circuit. When synchronously scanning the mask M and the wafer W during scanning exposure, both control circuits cooperatively control the mask stage 3 and the wafer stage 13. Further, the main control system 10 exchanges commands and parameters with each control circuit in the stage control system 11, and executes an optimum exposure process according to a program designated by the operator. For this purpose, an operation panel unit (not shown) (including an input device and a display device) that provides an interface between the operator and the main control system 10 is provided.

Furthermore, it is necessary to align the mask M and the wafer W in advance for exposure. 1 is provided with a reticle alignment system (not shown) for setting the mask M at a predetermined position and an alignment system (not shown) for detecting marks on the wafer W. Yes.
When the exposure apparatus shown in FIG. 1 performs exposure, exposure of the exposure beam IL to the mask M is started, and an image of a part of the pattern of the mask M via the projection optical system PL is taken as one shot area on the wafer W. The mask M is placed in the shot area by a scanning exposure operation in which the mask stage 3 and the wafer stage 13 are moved synchronously in the X direction (synchronous scanning) with the projection magnification β of the projection optical system PL as the speed ratio. The pattern image is transferred. Thereafter, the irradiation of the exposure beam IL is stopped, and the step-and-scan method is performed by repeating the operation of moving the wafer W stepwise in the X and Y directions via the wafer stage 13 and the above scanning exposure operation. Thus, the pattern image of the mask M is transferred to all the shot areas on the wafer W.

Next, a mechanism for supporting a plurality of concave mirrors 24 to 26 (mirrors) that are optical members of the projection optical system PL of this example will be described in detail.
In FIG. 1, the projection optical system PL includes a box-shaped first frame 21 whose top is open, and a flat plate-like second frame 22 disposed so as to cover the first frame 21. In this case, the first frame 21 is installed on a floor (not shown) via, for example, three or more vibration isolation tables, and the exposure beam IL is passed through the side surfaces of the first frame 21 in the −X direction and the + X direction, respectively. Window portions 21a and 21b are formed. The second frame 22 is installed on the first frame 21 via three or more vibration isolation tables 23A and 23B (the third and subsequent vibration isolation tables are not shown). Since the second frame 22 is used as a reference frame (a frame mechanism that supports the connecting member) that serves as a reference for the positions of the concave mirrors 24 to 26 in the projection optical system PL, the second frame 22 has a low expansion such as invar so that the positional accuracy is stabilized. Is formed from rate material. Reference mirrors 9M and 9W of the mask side laser interferometer system and the wafer side interferometer system are also fixed to the second frame 22.

  Concave mirrors 24 to 26 are arranged in a vacuum atmosphere, which is a space surrounded by the first frame 21 and the second frame 22, in a state (off-axis state) gradually shifted laterally in the X direction. In this example, the concave mirrors 24 and 26 at both ends are disposed at positions close to the upper surface of the first frame 21, and the intermediate concave mirror 25 is disposed at a position close to the bottom surface of the second frame 22. IL enters the wafer W sequentially through the window portion 21a, the concave mirror 24, the concave mirror 25, the concave mirror 26, and the window portion 21b. Each of the concave mirrors 24 to 26 is formed by, for example, forming a reflective film that reflects EUV light on the concave surface portion of a disk-shaped glass substrate.

  FIG. 2 is a perspective view showing a support state of the concave mirror 24 in the −X direction in FIG. 1. In FIG. 2, the concave mirror 24 is housed in a concave portion on the upper surface of a metal disk-shaped lens frame 27. The lens frame 27 is connected to steel wires 30A, 30B, and 30C (wire members) at three locations, and the wires 30A, 30B, and 30C are vibration-proof pads 31A, 31B, and 31C (support devices or vibrations), respectively. 1 is connected to the second frame 22 of FIG. The wires 30 </ b> A to 30 </ b> C are connected to positions at which the peripheral edge of the lens frame 27 is substantially an apex of an equilateral triangle and do not block the optical path of the exposure beam. The mechanisms composed of the wires 30A to 30C and the vibration isolation pads 31A to 31C correspond to the connecting members, respectively. In FIG. 1, the wire 30C and the vibration isolation pad 31C are not shown.

  Returning to FIG. 1, the lens frame 27 and the concave mirror 24 (a rigid structure having high rigidity) are vertically formed using three sets of connecting members (a flexible structure having low rigidity) from the second frame 22 (a rigid structure having high rigidity). It is supported by hanging in the direction. By the connecting member, vibration and heat conduction from the second frame 22 to the concave mirror 24 are reduced. Instead of the wires 30 </ b> A to 30 </ b> C, for example, a rod member provided with a flexure (a highly flexible portion) at the front end portion and the lower end portion can be used.

In this case, the natural frequency of the wire 30A in one connecting member is lower in the horizontal direction perpendicular to the Z axis than in the Z direction (vertical direction). Since the wire 30A vibrates like a pendulum in the horizontal direction, if the length in the Z direction of the wire 30A is L and the gravity constant is G (= 9.8 m / s ² ), the natural vibration in the horizontal direction The number fg becomes smaller as the length L becomes longer as follows.

fg = {1 / (2π)} (G / L) ^1/2 (1)
As the natural frequency fg is smaller, the vibration isolation performance of the horizontal concave mirror 24 (the ability to prevent floor vibration from being transmitted to the concave mirror 24) is improved. To increase the vibration isolation performance of the wire 30A, The longer the length L, the better. However, on the other hand, in order to easily assemble and adjust the projection optical system PL, in order to house the connecting member in the projection optical system PL, the length L of the wire 30A is from the connecting member to the lens frame 27. It is necessary to determine such that the members of the first and second frames 21 and 22 are accommodated. If the length L of the wire 30A is set to 1 m or more, the natural frequency fg is about 0.5 Hz or less, which is sufficiently small for the exposure apparatus as follows from the equation (1).

fg ≦ 0.5 (Hz) (2)
Thus, the concave mirror 24 can obtain high vibration isolation performance in the horizontal direction by the wire 30A. However, since the natural frequency in the Z direction (vertical direction) of the wire 30A is considerably higher than the natural frequency fg in the horizontal direction, the vibration isolation performance in the vertical direction of the concave mirror 24 is lowered as it is. Therefore, in order to improve the vibration isolation performance in the vertical direction of the connecting member, anti-vibration pads 31A to 31C are provided on the wires 30A to 30C in the connecting member. The anti-vibration pads 31A to 31C in this example connect the second frame 22 (frame mechanism), the wires 30A to 30C, the lens frame 27, and the concave mirror 24 with low rigidity using atmospheric pressure. Moreover, since the upper and lower members are connected substantially non-contact using atmospheric pressure, a high heat insulating effect is also obtained.

Hereinafter, the configuration of the vibration-proof pad 31A (support device or damping mechanism) will be described. The configuration of the other anti-vibration pads 31B and 31C is the same as that of the anti-vibration pad 31A.
FIG. 3 is a cross-sectional view showing the vibration isolation pad 31A in FIG. 1, and the vibration isolation pad 31A is installed in a vacuum atmosphere. In FIG. 3, a support member 40 having a circular opening formed at the center and spacer portions at both ends is fixed to the bottom surface of the second frame 22, and the circular opening is covered on the bottom surface of the support member 40. A cylinder 41 (cylinder portion) that is cylindrical and has a closed bottom surface is fixed. In addition, a cylindrical piston 42 (piston part) is disposed in a state where it can move up and down (± Z direction) with a certain gap in the cylinder 41, and the upper part of the piston 42 is located downward at each of the three locations. Via the bent arms 43 a, 43 b and 43 c (see FIG. 4), it is connected to a disk-like member 43 disposed below the cylinder 41, and the wire 30 </ b> A is connected to the bottom surface of the disk-like member 43.

4 is a perspective view showing the vibration isolating pad 31A when the support member 40 of FIG. 3 is represented by a two-dot chain line. In FIG. 4, the support member 40 has three locations surrounding the central circular opening. Are formed with rectangular openings 40a, 40b, 40c, and arms 43a-43c are inserted into these openings 40a-40c, respectively.
Returning to FIG. 3, an opening 41a is formed on the side surface of the cylinder 41, and openings 41b and 41c are formed so as to sandwich the opening 41a in the Z direction. Then, an external air compressor (not shown) is connected to the opening 41a via the air supply pipe 44, and compressed air highly dedusted is supplied from the air supply pipe 44 to the space B1 between the cylinder 41 and the piston 42. Yes. As a result, the cylinder 41 and the piston 42 slide in the Z direction without contact via the air bearing. Further, since the compressed air flows into the space B2 on the bottom surface side of the piston 42 in the cylinder 41, the piston 42 and the wire 30A are pushed upward (+ Z direction) by the compressed air and supported. Yes. With this configuration, the second frame 22 and the wire 30A are connected in a non-contact manner.

  Further, in order to stably maintain the pressure of the compressed air in the space B2, the openings 41b and 41c are connected to predetermined gas chambers (not shown) via exhaust pipes 45A and 45B (exhaust portions or pipes), respectively. This gas chamber communicates with a space having the same atmospheric pressure as the atmospheric pressure via a dust filter. Actually, as shown in FIG. 4, the exhaust pipes 45 </ b> A and 45 </ b> B are connected to the gas chambers via the synthesis unit 46 and the exhaust pipe 47. In FIG. 3, the openings 41b and 41c of the cylinder 41 communicate with the space where the internal atmospheric pressure is the same as the atmospheric pressure via the exhaust pipes 45A and 45B. Further, an exhaust groove 41d is formed in the upper part of the inner surface of the cylinder 41 so as to continue to the opening 41c. In the present embodiment, the vibration isolation pad 31A includes the support member 40, the cylinder 41, the piston 42, the arms 43a to 43c, the disk-like member 43, the air supply pipe 44, and the exhaust pipes 45A and 45B. However, the present invention is not limited to this, and various configurations can be taken as described later.

  In the vibration isolating pad 31A, the compressed air that passes upward through the space between the cylinder 41 and the piston 42 is released from the groove 41d and the opening 41c to the atmospheric pressure space through the exhaust pipe 45B. Accordingly, the space (enclosure) surrounding the cylinder 41 is maintained in a vacuum atmosphere. Even if the piston 42 is pushed down in the cylinder 41 and the volume of the space B2 changes, the space B2 communicates with the atmospheric pressure space via the exhaust pipe 45A, so that the pressure in the space B2 is stable. Maintained. Accordingly, the piston 42 and the wire 30A, and hence the lens frame 27 and the concave mirror 24 of FIG. 1, are always supported so as to float at a substantially constant pressure. Therefore, even if the second frame 22 vibrates in the Z direction, the vibration is not transmitted to the wire 30 </ b> A, and thus high vibration isolation performance can be obtained in the vertical direction.

The vibration-proof pad 31A (support device or damping mechanism) includes a mechanical mechanism using a coil spring, a non-contact electromagnetic actuator such as a voice coil motor, in addition to a mechanism using atmospheric pressure as in this example. A mechanism using the above, a mechanism combining them, or the like can also be used.
As described above, the rigid concave mirror 24 and the lens frame 27 of this example are suspended from the rigid second frame 22 via the vibration isolation pads 31A to 31C and the wires 30A to 30C as flexible connection members. Lowered and supported. With this structure, high vibration isolation performance can be obtained and the mechanical portion can be significantly reduced in weight, but the relative position between the lens frame 27 (and the concave mirror 24) and the second frame 22 (reference frame) is relatively low. May change with frequency. In order to maintain the relative position between the lens frame 27 and the second frame 22 in a predetermined state, a non-contact type 6-degree-of-freedom position adjustment mechanism is provided. A 6-DOF displacement sensor is provided to measure the position of the lens frame 27 when driving the position adjusting mechanism. The measurement information of the displacement sensor is supplied to the mirror control system 12 of FIG. 1, and the mirror control system 12 has the lens frame 27 and the concave mirror 24 based on the measurement information and the target position information from the main control system 10. The position adjustment mechanism is driven so as to approach the target position.

  In FIG. 1, the position adjusting mechanism includes three non-contact type Z-axis actuators 33 </ b> A, 33 </ b> B that generate thrust in the Z direction disposed between the bottom surface of the lens frame 27 and the top surface of the first frame 21. 33C is provided. The Z-axis actuators 33A to 33C are disposed at positions that are substantially vertexes of a regular triangle on the bottom surface of the lens frame 27, and can finely adjust the position of the lens frame 27 in the Z direction independently of each other. The Z-axis actuators 33 </ b> A to 33 </ b> C each include a moving magnet type voice coil including a mover including a permanent magnet fixed to the lens frame 27 and a stator including a coil fixed to the first frame 21. It is a motor.

  That is, as shown in FIG. 2, the Z-axis actuators 33A and 33B are respectively composed of a mover 33Aa and 33Ba fixed to the lens frame 27 and a stator 33Ab and 33Bb fixed to the first frame 21 of FIG. It is configured. The movers 33Aa and 33Ba include permanent magnets arranged at a predetermined pitch, the stators 33Ab and 33Bb include coils, and the current of the coils is controlled by the mirror control system 12. By controlling the thrust in the Z direction of the three Z axis actuators 33A to 33C in FIG. 1, the position of the lens frame 27 (and the concave mirror 24) in the Z direction, the tilt angle around the X axis, and the Y axis around Can be finely adjusted.

  In FIG. 2, the position adjusting mechanism includes three non-contact XY-axis actuators 32A, 32B, and 32C that generate thrust in the radial direction, which are arranged on the side surface of the lens frame 27 at substantially equal angular intervals. I have. The XY-axis actuators 32A to 32C are moving magnet type voice coil motors that can finely adjust the radial position of the lens frame 27 independently of each other. That is, the XY axis actuators 32A, 32B, and 32C are respectively movable elements 32Aa, 32Ba, and 32Ca including permanent magnets fixed to the lens frame 27, and a stator 32Ab including coils fixed to the first frame 21 of FIG. , 32Bb, 32Cb, and the current of the coil is controlled by the mirror control system 12. As shown in FIG. 1, the stator 32Bb is fixed to the first frame 21 via an attachment member 34A. Similarly, the stator 32Cb of FIG. 2 is also attached to the first frame 21 via an attachment member (not shown). It is fixed. The mirror control system 12 finely adjusts the position of the lens frame 27 in the X and Y directions and the rotation angle around the Z axis by independently controlling the currents of the coils of the three XY axis actuators 32A to 32C. be able to.

  In this way, by using the 6-axis Z-axis actuators 33A to 33C and the XY-axis actuators 32A to 32C in total, the lens frame 27 and the concave mirror 24 with respect to the first frame 21 (finally with respect to the second frame 22) 6 The degree of freedom displacement is controlled in a non-contact manner. The response frequencies of the actuators 33A to 33C and 32A to 32C in this example are about 10 Hz, and the lens frame 27 and the concave mirror 24 are supported by an active suspension system against vibrations up to the response frequency. The lens frame 27 and the concave mirror 24 are suspended and supported by a passive vibration-proof structure against vibrations having a frequency exceeding that.

  Further, since the six-axis Z-axis actuators 33A to 33C and the XY-axis actuators 32A to 32C are of a moving magnet type, it is not necessary to route wiring around the lens frame 27. Therefore, the displacement control of the lens frame 27 and the concave mirror 24 can be performed with high accuracy. Furthermore, since the lens frame 27 is substantially in a stationary state, the amount of heat generated by the coils of each actuator is small, and the lens frame 27 is separated from the coil, so that the lens frame 27 and the concave mirror 24 have high temperature stability. can get. Further, a coolant pipe for cooling the coil may be disposed on the inner surface of the first frame 21. Even in this case, an unnecessary load is not applied to the lens frame 27. The same applies to the other concave mirrors 25 and 26. Since the projection optical system PL of this example has high vibration isolation performance and temperature stability of each optical member, the imaging characteristics are also maintained high. In addition to the voice coil motor, for example, a non-contact electromagnetic actuator such as an EI core system can be used as these actuators.

  Returning to FIG. 1, the central concave mirror 25 is also supported in the same manner as the concave mirror 24. However, the concave mirror 25 is different in that the reflecting surface faces downward. That is, the concave mirror 25 (optical member) is housed in a metal lens frame 28 and is fixed by a pressing ring 28C. The lens frame 28 is made of steel wires 30D and 30E (the third wire is formed in three places). The three wires 30D and 30E are connected to the second frame 22 via vibration-proof pads 31D and 31E (supporting device or damping mechanism), respectively. Vibration and heat conduction from the second frame 22 to the concave mirror 25 are reduced by a mechanism (connecting member) including the three wires 30D and 30E and the corresponding three anti-vibration pads 31D and 31E.

  Also in this case, if the length in the Z direction of one connecting member (the wire 30D and the vibration isolating pad 31D) is L, the natural frequency fg in the direction perpendicular to the Z axis of the connecting member is expressed by Equation (1). Determined. The longer the length L, the smaller the natural frequency fg. However, since the concave mirror 25 is disposed at a position close to the second frame 22, the length L is shorter than that of the concave mirror 24. In this example, in order to make the length L as long as possible, the anti-vibration pads 31D and 31E that support the wires 30D and 30E are connected to the recess 22a on the bottom surface of the second frame 22. Assuming that the length L of the connecting member connected to the concave mirror 25 can be set to about 0.5 m as an example, the natural frequency fg is approximately 0.7 Hz, which is a sufficiently small value during normal exposure from the equation (1). become.

  Further, in order to maintain the relative position of the lens frame 28 and the concave mirror 25 and the second frame 22 in a predetermined state, a non-contact type 6-degree-of-freedom position adjustment mechanism is provided, and when this position adjustment mechanism is driven. In order to measure the position of the lens frame 28, a displacement sensor having 6 degrees of freedom is provided. This is the same as in the case of the concave mirror 24. Based on the measurement information of the displacement sensor 24, the mirror control system 12 drives the position adjustment mechanism so that the lens frame 28 and eventually the concave mirror 25 approach the target position.

  The position adjusting mechanism includes three non-contact Z-axis actuators 33D and 33E that generate thrust in the Z direction disposed between the bottom surface of the lens frame 28 and the mounting member 34B fixed to the second frame 22. , 33F. The Z-axis actuators 33D to 33F are moving magnet type voice coil motors. Further, the position adjusting mechanism includes three non-contact type XY-axis actuators 32D and 32E that generate thrust in the radial direction arranged on the side surface of the lens frame 28 at substantially equal angular intervals (the third XY-axis actuator is (Not shown). The XY axis actuators 32D and 32E are moving magnet type voice coil motors, and their stators are fixed to the second frame 22 via attachment members (not shown). By using these 6-axis XY-axis actuators 32D and 32E and Z-axis actuators 33D to 33F, displacement of the lens frame 28 and the concave mirror 25 with respect to the second frame 22 (in the X, Y, and Z directions). The position and the inclination angles around the X, Y, and Z axes) are controlled in a non-contact manner.

  Further, the concave mirror 26 in the + X direction is also supported in the same manner as the concave mirror 24. That is, the concave mirror 26 (optical member) is housed and fixed in a metal lens frame 29, and the lens frame 29 is connected to steel wires 30G and 30H (the third wire is not shown) at three locations. The three wires 30G and 30H are connected to the second frame 22 via vibration-proof pads 31G and 31H (supporting device or damping mechanism), respectively. Since the length of the connecting member of the concave mirror 26 is about the same as that of the concave mirror 24, the natural frequency in the horizontal direction of the concave mirror 26 is kept as low as the concave mirror 24.

  Further, in order to maintain the relative position of the lens frame 29 and the concave mirror 26 and the second frame 22 in a predetermined state, a non-contact type 6-degree-of-freedom position adjustment mechanism is provided, and when this position adjustment mechanism is driven. In order to measure the position of the lens frame 29, a displacement sensor with six degrees of freedom is provided. This is the same as in the case of the concave mirror 24. Based on the measurement information of the displacement sensor, the mirror control system 12 drives the position adjusting mechanism so that the lens frame 29 and, consequently, the concave mirror 26, approaches the target position.

  The position adjustment mechanism includes three non-contact type Z-axis actuators 33G, 33H, and 33I that generate thrust in the Z direction, which are disposed between the bottom surface of the lens frame 29 and the first frame 21. Further, the position adjusting mechanism includes three non-contact XY-axis actuators 32G and 32H that generate thrust in the radial direction, which are arranged on the side surface of the lens frame 29 at substantially equal angular intervals (the third XY-axis actuator is (Not shown). The Z-axis actuators 33G to 33I and the XY-axis actuators 32G and 32H are moving magnet type voice coil motors, and the stator of the XY-axis actuator 32G is fixed to the first frame 21 via an attachment member 34C.

Next, the configuration of the laser interferometer system as a displacement sensor for measuring the displacement of 6 degrees of freedom of the lens frame 27 and the concave mirror 24 of FIG. 1 will be described with reference to FIGS.
FIG. 5 shows a laser interferometer system for measuring the displacement of the lens frame 27 and the concave mirror 24. In FIG. 5, two reflections perpendicular to each other are provided on the upper surface of the peripheral portion of the lens frame 27 at three equiangular intervals. Corner mirror portions 27a, 27b, and 27c (moving mirrors) having surfaces are formed. Straight lines (hereinafter referred to as “ridge lines”) obtained by extending the intersecting lines of the two reflecting surfaces of the three corner mirror portions 27a to 27c are arranged at intervals of 120 ° on a certain plane. Intersects in the vicinity of a straight line passing through the center of the concave mirror 24 and parallel to the Z-axis. The corner mirror portions 27a to 27c can be formed by, for example, mirror-processing a part of the lens frame 27, but a corner mirror having two reflection surfaces made of glass is embedded in the cutout portion of the lens frame 27. But you can.

  In this example, by measuring the horizontal direction (lateral direction) position and the Z direction position (height) of the three ridge lines as an example, the position of the lens frame 27 (concave mirror 24) with six degrees of freedom is determined. Determine uniquely. For example, two measurement beams having different angles are applied to one corner mirror portion 27a from a laser interferometer fixed to the second frame 22 in FIG. By using these measurement beams, a plane with the two measurement beams as normals is defined, and the intersection of these two planes becomes one ridge line, so the distance to the two planes can be measured. The position of the ridgeline in the horizontal direction and the Z direction can be measured.

In order to perform the measurement, biaxial laser interferometers 50A, 50B, and 50C are disposed above the corner mirror portions 27a, 27b, and 27c of the lens frame 27, respectively. The members constituting the laser interferometers 50A to 50C are actually fixed to the bottom surface of the second frame 22 (frame mechanism) in FIG. 1 directly or via a predetermined attachment member.
Since the three laser interferometers 50A to 50C have the same configuration, the configuration of the laser interferometer 50A will be described below. In the laser interferometer 50A, a laser beam having a predetermined wavelength emitted from the laser light source 35 is divided into two by a beam splitter 36, and one laser beam L1 is further divided into a measurement beam L1m and a reference beam L1r by a polarization beam splitter 37A. . As an example, a polarizing beam splitter 38A (reference mirror) for photosynthesis is fixed to the polarizing beam splitter 37A, and the reference beam L1r reflected by the former polarizing beam splitter 37A is reflected again by the polarizing beam splitter 38A. On the other hand, the measurement beam L1m transmitted through the polarizing beam splitter 37A enters the corner mirror portion 27a, is reflected in the opposite direction parallel to the incident direction, passes through the polarizing beam splitter 38A, and is combined with the reference beam L1r. The combined measurement beam L1m and reference beam L1r enter the photoelectric detector 39A via a polarizing plate (not shown), and the detection signal of the photoelectric detector 39A is supplied to the position detection unit of the mirror control system 12. In the position detection unit, the position of one reflection surface of the corner mirror unit 27a is measured, for example, with a resolution of about 1 nm with reference to the position of the polarization beam splitter 38A.

  The other laser beam L2 divided by the beam splitter 36 is incident on the polarization beam splitter 37B via a light transmission optical system (not shown) and divided into two. As an example, a polarization beam splitter 38B (reference mirror) for light synthesis is also fixed to the polarization beam splitter 37B, and the reference beam L2r reflected by the former polarization beam splitter 37B is reflected again by the polarization beam splitter 38B. On the other hand, the measurement beam L2m transmitted through the polarizing beam splitter 37B is incident on the corner mirror portion 27a, reflected in the opposite direction parallel to the incident direction, and transmitted through the polarizing beam splitter 38B to be combined with the reference beam L2r. The combined measurement beam L2m and reference beam L2r are incident on the photoelectric detector 39B via a polarizing plate (not shown), and the detection signal of the photoelectric detector 39B is supplied to the position detection unit of the mirror control system 12. In the position detection unit, the position of the other reflecting surface of the corner mirror unit 27a is measured with a resolution of about 1 nm, for example, with the position of the polarization beam splitter 38B as a reference. In the present embodiment, the laser interferometer 50A includes the laser light source 35, the beam splitter 36, the polarization beam splitters 37A and 37B, the polarization beam splitters 38A and 38B, and the photoelectric detectors 39A and 39B. The configuration is not necessarily limited to this. Further, the laser light source 35 and the photoelectric detectors 39A and 39B correspond to the interferometer unit.

  FIG. 6 is an enlarged view showing the corner mirror portion 27a in FIG. 5. In FIG. 6, the measurement beams L1m and L2m are substantially symmetrical and incident on the two reflecting surfaces A1 and A2 of the corner mirror portion 27a, respectively. The light is incident so that the surface is substantially perpendicular to the reflection surfaces A2 and A1. At this time, since the reflection surfaces A1 and A2 are perpendicular to each other, the measurement beam L1m incident on the reflection surface A1 is then reflected by the reflection surface A2 in a reverse direction substantially parallel to the incident direction with respect to the reflection surface A1. In contrast, the measurement beam L2m incident on the reflecting surface A2 is then reflected by the reflecting surface A1 in the opposite direction substantially parallel to the incident direction with respect to the reflecting surface A2. By using the corner mirror portion 27a in this way, the horizontal direction of the ridgeline of the corner mirror portion 27a and the horizontal direction of the corner mirror portion 27a using the measurement beams L1m and L2m can be obtained even if the position in the horizontal direction and the Z direction of the lens frame 27 changes at that position. The position in the Z direction can be measured with high accuracy.

  Returning to FIG. 5, the other laser interferometers 50 </ b> B and 50 </ b> C similarly supply a detection signal including position information of the corner mirror units 27 b and 27 c in two directions to the position detection unit of the mirror control system 12. In the position detection unit, the positions of the ridgelines of the corner mirror units 27b and 27c in the horizontal direction and the Z direction are measured with a resolution of about 1 nm, for example, with reference to the position of the polarization beam splitter in the laser interferometers 50B and 50C. At this time, if the lens frame 27 is at the target position, the positions of the three ridge lines coincide with the positions of the predetermined target straight lines. When the lens frame 27 is slightly displaced, the position and orientation of the lens frame 27 are uniquely determined from the positions of the three ridge lines of the corner mirror portions 27a to 27c. Therefore, as an example, in the position detection unit, the six-axis non-contact XY-axis actuators 32A to 32C (see FIG. 2) and Z of FIG. 1 are set so that the positions of the three ridge lines are returned to the target positions. The operation of the shaft actuators 33A to 33C is controlled. Thereby, the positions of the lens frame 27 and the concave mirror 24 are maintained at target positions with respect to the second frame 22.

  As another processing method, the lens frame 27 and the concave mirror 24 shown in FIG. 1 are processed by processing the two-direction positions (position information of 6 degrees of freedom in total) of the three corner mirror portions 27a to 27c. The positions in the X direction, Y direction, and Z direction with respect to the second frame 22 and the inclination angles around the X axis, Y axis, and Z axis may be obtained. Also by using information on these positions and inclination angles, the operations of the six-axis XY-axis actuators 32A to 32C and the Z-axis actuators 33A to 33C in FIG. 1 can be controlled with high accuracy.

  Similarly, a 6-axis laser interferometer system (not shown) is also arranged for each of the concave mirror 25 (lens frame 28) and the concave mirror 26 (lens frame 29) of FIG. A displacement of 6 degrees of freedom with respect to the 26th second frame 22 is measured. It should be noted that an acceleration sensor or a position sensor can be used as a displacement sensor for detecting the displacement of the concave mirrors 24 to 26 (lens frames 27 to 29) with six degrees of freedom. As an acceleration sensor, a piezoelectric acceleration sensor that detects a voltage generated by a piezoelectric element (piezo element or the like), or a semiconductor type that utilizes a change in the logical threshold voltage of a CMOS converter according to the magnitude of strain, for example. An acceleration sensor or the like can be used. Further, as the position sensor, for example, a non-contact type sensor such as an eddy current displacement sensor, a capacitance type displacement sensor, or an optical sensor can be used.

Note that the position adjustment mechanisms of the concave mirrors 24 to 26 such as the six-axis XY-axis actuators 32A to 32C and the Z-axis actuators 33A to 33C in FIG. 1 can also be used as a mechanism for correcting the imaging characteristics of the projection optical system PL. Good. In this example, since the displacements of the concave mirrors 24 to 26 can be predicted fairly accurately, the imaging characteristics can be corrected with high accuracy.
As described above, in the projection optical system PL of the exposure apparatus of this example, the anti-vibration pads 31A to 31C or the like as flexible connecting members and the wires 30A to 30C or the like are connected to the rigid second frame 22. The lens frame 27 having a rigid structure and the concave mirror 24 are suspended and supported by an active suspension system. For this reason, there are the following advantages.

1) The projection optical system PL is composed of a very simple combination of structures, the mechanism can be reduced in weight, and the manufacturing cost can be reduced.
2) Since the lens frames 27 to 29 (concave mirrors 24 to 26) are suspended and supported, and the natural frequency of the vibration of the connecting member in particular in the horizontal direction is extremely small, the influence of vibration from the floor surface is greatly reduced. Is done. Therefore, apparatus performance such as vibration isolation performance and exposure accuracy (overlay accuracy) is improved. And even if vibration becomes a problem, it is easy to specify the transmission path, and for example, it is possible to easily take measures such as adding an anti-vibration member to a portion where vibration is transmitted.

3) Since the thermal deformation of the structure can be easily predicted when the environmental temperature of the exposure apparatus changes, positioning errors based on the measurement results can be obtained by measuring the temperature of each part of the structure using a temperature sensor. Etc. can also be corrected.
4) Since there is a wide space around the optical member in the projection optical system PL, the degree of freedom in design increases, and it can be said that the structure is suitable for so-called module design.

  Note that the exposure apparatus of the above-described embodiment incorporates an illumination optical system and projection optical system composed of a plurality of mirrors into the exposure apparatus main body and performs optical adjustment to expose a mask stage and wafer stage made up of a large number of mechanical parts. It can be manufactured by attaching to the main body of the apparatus, connecting wiring and piping, and performing general adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  Further, when a semiconductor device is manufactured using the exposure apparatus of the above-described embodiment, the semiconductor device includes a step of designing a function and performance of the device, a step of manufacturing a reticle based on this step, and a wafer from a silicon material. Forming step, aligning with the exposure apparatus of the above-described embodiment to expose the pattern of the reticle onto the wafer, forming circuit pattern such as etching, device assembly step (including dicing process, bonding process, and packaging process) ) And an inspection step.

In the present invention, excimer laser light (KrF excimer laser light with a wavelength of 248 nm, ArF excimer laser light with a wavelength of 193 nm, etc.), F ₂ laser light (wavelength of 157 nm), or solid-state laser (YAG laser or semiconductor) is used as a projection beam. The present invention can also be applied to the case of supporting a projection optical system such as a refraction type or a catadioptric type of an exposure apparatus that uses ultraviolet light having a wavelength of about 100 to 300 nm such as a harmonic of a laser. Needless to say, the supporting optical member may be a lens (refractive member) as well as a mirror such as a concave mirror or a plane mirror. The present invention can also be applied to support a projection optical system mounted on an immersion type exposure apparatus disclosed in, for example, International Publication (WO) No. 99/49504.

  In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to an exposure apparatus for manufacturing various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithographic process.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various structure can be taken in the range which does not deviate from the summary of this invention.

  According to the exposure apparatus of the present invention, since the projection optical system having a simple and lightweight configuration is used while being excellent in vibration isolation performance, the exposure accuracy can be maintained high, and the weight and cost of the mechanism can be reduced. It becomes possible.

It is the figure which made the cross section the part which shows the schematic structure of the exposure apparatus of an example of embodiment of this invention. It is a perspective view which shows the support state of the concave mirror 24 and the lens frame 27 in FIG. It is the figure which made the cross section the part which shows 31 A of vibration-proof pads in FIG. It is a perspective view which shows 31 A of vibration isolating pads when the supporting member 40 of FIG. 3 is represented with a dashed-two dotted line. It is a perspective view which shows the laser interferometer system for the displacement measurement of the concave mirror 24 and the lens frame 27 in FIG. It is an enlarged view which shows the corner mirror part 27a of FIG.

Explanation of symbols

M ... Mask, 3 ... Mask stage, PL ... Projection optical system, W ... Wafer, 13 ... Wafer stage, 21 ... First frame, 22 ... Second frame, 24, 25, 26 ... Concave mirror, 27, 28, 29 ... Lens frame, 27a, 27b, 27c ... corner mirror part, 30A-30C, 30D, 30E, 30G, 30H ... wire, 31A-31C, 31D, 31E, 31G, 31H ... anti-vibration pad, 32A-32C, 32D, 32E , 32G, 32H ... XY axis actuator, 33A to 33C, 33D to 33F, 33G to 33I, Z axis actuator, 41 ... Cylinder, 42 ... Piston, 45A, 45B ... Exhaust pipe, 50A-50C ... Laser interferometer

Claims (15)

In a projection optical system that projects a pattern image,
A plurality of optical members for guiding the beam from the pattern to the image plane;
A projection optical system comprising: a connecting member that suspends and supports at least one of the plurality of optical members. The plurality of optical members are arranged in a vacuum atmosphere,
The projection optical system according to claim 1, wherein the connecting member includes a support device that supports the at least one optical member using atmospheric pressure. The support device is
A cylinder part to which the atmospheric pressure is supplied;
A piston portion that is levitated and supported in the cylinder portion by the atmospheric pressure, and connected to the at least one optical member;
The projection optical system according to claim 2, further comprising: an exhaust portion that keeps the surrounding portion surrounding the cylinder portion in a vacuum atmosphere.   4. The projection optical system according to claim 1, wherein the connecting member suspends and supports the at least one optical member in the projection optical system. 5.   The projection optical system according to any one of claims 1 to 4, wherein the connecting member includes three wire members or rod members for each of the optical members supported by being suspended.   The projection optical system according to any one of claims 1 to 5, wherein the connecting member includes three wire members or three rod members.   The projection optical system according to claim 1, wherein the coupling member includes a damping mechanism that attenuates vibration of the at least one optical member. The damping mechanism is
A cylinder part to which gas is supplied;
A piston part that is housed in the cylinder part and supported by being floated by the gas, and connected to the optical member that is supported by being suspended;
The projection optical system according to claim 7, further comprising a pipe for exhausting gas leaking from the cylinder portion.   The projection optical system according to claim 1, wherein the optical member that is supported by being suspended is a mirror that reflects the beam. A frame mechanism for supporting the connecting member;
The projection according to any one of claims 1 to 9, further comprising a displacement sensor that measures displacement of each of the optical members supported by being suspended with respect to the frame mechanism with six degrees of freedom. Optical system.   The displacement sensor detects displacement of two degrees of freedom with respect to the three movable mirrors provided on the optical member to be measured, the reference mirror provided on the frame mechanism, and the three movable mirrors with respect to the reference mirror. The projection optical system according to claim 10, further comprising an interferometer unit.   The projection optical system according to claim 10, further comprising a position adjustment mechanism that positions each optical member supported by being suspended in a non-contact manner with respect to the frame mechanism with six degrees of freedom. .   The projection optical system according to any one of claims 10 to 12, wherein the frame mechanism is formed of a material having a low expansion coefficient. An exposure apparatus comprising the projection optical system according to any one of claims 1 to 13,
An exposure apparatus for transferring an image of the pattern on the substrate by the projection optical system. The exposure apparatus according to claim 14, wherein the beam is extreme ultraviolet light having a wavelength of 1 to 100 nm, and each of the plurality of optical members constituting the projection optical system is a mirror.

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