JPH1047914A - Moving mirror-supporting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid dislocation of a moving mirror supported on a sample object even when it is moved, and also to suppress deformation of a reflection surface of the moving mirror. SOLUTION: A moving mirror 10 is horizontally placed on a bottom surface supporting surface 32A formed on the upper surface of a protruded part 14 of a stage 12, and through a mounting hole 18A of the moving mirror 10 and its through hole 19, a bolt 30 is inserted from above, so that a rod-like part 30B of the bolt 30 is screwed into a threaded hole 34 for tight-fixing. Between a head part 30A of the bolt 30 and a bottom surface 38 of the mounting hole 18A, a spherically protruded part 48 and a spherically recessed part 47 are assigned facing each other, in addition, between the spherically recessed part 47 and the bottom surface 38, a sliding plate 46 is assigned. The bottom surface supporting surface 32A which supports the moving mirror 10 is a protrusion-like surface 36 where the height gradually increases starting from both end parts in measurement direction (arrow A direction) to a center part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving mirror supporting mechanism, and more particularly, to a moving mirror supporting mechanism for supporting a moving mirror, which forms a part of an interferometer, on an object to be measured.

[0002]

2. Description of the Related Art Conventionally, in a sequential movement type reduction projection type exposure apparatus (so-called stepper) or the like used in a lithography process in the manufacture of semiconductor elements or the like, a moving stage which moves in a biaxial direction on a plane as an exposure stage. (XY
Stage is provided, and a light wave interferometer is used as a device for measuring a position (distance) using interference of coherent light such as laser light in order to measure the X coordinate position and the Y coordinate position of the moving stage. Have been.

Normally, in this type of apparatus, a reflecting mirror (moving mirror) is provided at an end on a moving stage, which is an object to be measured, in a direction orthogonal to the measuring direction, and an interference is caused by a fixed portion outside the stage facing the mirror. A frequency stabilizing laser (eg, a He-Ne laser) from the interferometer to the moving mirror
And the interference of the reflected and incident laser light
Ultra-precision measurement in units of 1 μm is performed. Strictly speaking, in such an interferometer, it can be said that the movable mirror forms a part of the interferometer system in the sense that it cannot be measured without the movable mirror on the object to be measured.

FIG. 8 schematically shows an example of a mechanism for supporting a movable mirror on the stage side in this type of apparatus.

Usually, the movable mirror has a reflecting surface formed by vapor deposition of silver or the like on one surface of a glass body having a rectangular cross section, and the movable mirror 50 (shown by a two-dot chain line in FIG. 8).
In the direction of gravity, two movable mirror supporting surfaces (“island”) projecting from the upper surface of a band-shaped convex portion 54 having a predetermined width formed at one end on the stage 52 at a predetermined interval along the longitudinal direction thereof are provided. 56A and 56B. The movable mirror 50 is provided in the measurement direction (the direction of arrow A in the figure) on the inner side of the rectangular reference pieces 58A, 58B that are erected on one side of the movable mirror support surfaces 56A, 56B in the measurement direction. The pressurizing springs 64 are inserted from outside into the pressurizing pieces 62A, 62B erected on the other side in the measurement direction of the movable mirror supporting surfaces 56A, 56B and the rectangular supporting surfaces 60A, 60B.
A and 64B are sandwiched between pressurizing pins 66A and 66B (the ends of which are flat) urged toward the support surfaces 60A and 60B facing each other.

[0006]

However, in such a conventional movable mirror support mechanism, the stage 52 on which the movable mirror 50 shown in FIG. 8 is mounted is moved in a predetermined direction (for example, a measurement direction). When trying to drive, the reference piece 58
Moving mirror 50 held between supporting surfaces 60A, 60B of A, 58B and pressurizing pins 66A, 66B opposed thereto.
A force due to the driving acceleration acts on the pressure spring 64.
A, 64B expands and contracts, and the movable mirror 50 moves to the supporting surfaces 60A, 6B.
In some cases, the movable mirror 50 may not return to the original state in a state in which the movable mirror 50 is separated from the OB. As described above, the positional relationship (tilt, etc.) of the movable mirror 50 with respect to the stage 52 is different between before and after driving the stage 52, so that there is an inconvenience that the measured value of the interferometer is greatly deviated. .

Therefore, as described above, the reference pieces 58A, 5A
The movable mirror 50 is not supported by urging the movable mirror 50 with the pressurizing pins 66A and 66B against the supporting surfaces 60A and 60B of the 8B, and even if a driving acceleration is applied to the movable mirror 50 by driving the stage 52. To avoid misalignment,
It is conceivable that the movable mirror 46 is securely fixed to the stage 52.

However, the glass body constituting the movable mirror 46 is not a rigid body in an ideal sense, but can be minutely deformed by the action of a force. In addition, since the measurement by the interferometer has a very high measurement accuracy (0.01 μm unit), the fact that the deformation of the reflecting surface due to the support state of the movable mirror 46 greatly affects the measurement accuracy is as follows. It is common sense among those skilled in the art. For this reason, it has not been performed until now to securely fix the movable mirror to the stage using a fixture or the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned disadvantages of the related art, and has as its object to shift the position of a movable mirror supported on a measurement object even if the measurement object is moved. It is an object of the present invention to provide a movable mirror support mechanism capable of preventing deformation of the reflecting surface of the movable mirror while preventing the occurrence of the movable mirror.

[0010]

According to the first aspect of the present invention, there is provided a movable mirror having a rectangular cross section which constitutes a part of an interferometer.
Is a moving mirror supporting mechanism for supporting the moving mirror (10) perpendicularly to the measuring direction (the direction of arrow A) on the measuring object (12), wherein the moving mirror (10) is positioned on the measuring object (12) from above. At least two fixtures (30 or 4) respectively fixed to the mounting surface (16A, 16B or 32A, 32B)
0), and the fixed position for fixing the movable mirror (10) on the object to be measured (12) using the fixture (30 or 40) is a measurement surface (20) of the movable mirror (10). Is provided outside the range of use.

According to this, the movable mirror is securely fixed to the movable mirror mounting surface of the object to be measured by at least two fixtures from above the movable mirror, and their fixed positions are within the range of use of the measurement surface of the movable mirror. Since the movable mirror is not displaced even when the object to be measured is moved, even if the movable mirror is subjected to stress deformation by the fixture, the range of the deformation is kept out of the range of use of the measurement surface (reflection surface). This makes it possible to prevent the measurement result of the interferometer from being adversely affected.

According to a second aspect of the present invention, a movable mirror (10) having a rectangular cross section, which forms a part of an interferometer, is mounted on an object (1).
2) A moving mirror support mechanism for supporting the moving mirror at right angles to the measurement direction (the direction of arrow A).
It is arranged at a predetermined interval along a direction orthogonal to the measurement direction (arrow A direction), and its height gradually increases on the upper surface from at least both ends in the measurement direction (arrow A direction) toward the center. At least two movable mirror mounting surfaces (32A, 3A) formed with such convex surfaces (36).
2B); the at least two movable mirror mounting surfaces (3
2A, 32B) and a plurality of fixtures (30 or 40) for respectively fixing the movable mirror (10) from above to the measurement object (12).

According to this, since the upper surface of the movable mirror mounting surface is formed so as to gradually increase in height from both ends in the measurement direction to the central portion, the movable mirror mounting surface is formed on the movable mirror mounting surface. When the movable mirror is fixed from above by a fixture, even if the movable mirror is subjected to stress deformation, there is no movable mirror mounting surface at the position that hinders the deformation. Distortion can be prevented.

According to a third aspect of the present invention, a movable mirror (10) having a rectangular cross section, which forms a part of an interferometer, is mounted on an object (1).
2) A moving mirror support mechanism for supporting the moving mirror (10) from above from above the moving mirror mounting surface (16) on the measurement object (12).
A, 16B or 32A, 32B) and at least two fixtures (40) comprising a rod-shaped member (40B) for fixing to the rod-shaped member (40B) and a large-diameter portion (40A) provided at one end of the rod-shaped member (40B). And the upper surface (3) of the movable mirror (10).
8) The large-diameter portion (40A) of the fixture (40) opposed to (8)
Is formed in a spherical shape so as to gradually project toward the upper surface (38) of the movable mirror from the periphery to the center of the rod-shaped member (40B).

According to this, the surface of the large-diameter portion of the fixture facing the upper surface of the movable mirror has a spherical shape that gradually projects toward the upper surface of the movable mirror from the peripheral portion to the central portion of the rod-shaped member. Even if the upper surface of the movable mirror fixed by the fixture is inclined, the large diameter part of the fixture will not hit one side, preventing the occurrence of minimal stress concentration due to the one side of the fixture, and deforming the reflecting surface Can be prevented.

According to a fourth aspect of the present invention, in the movable mirror supporting mechanism according to any one of the first to third aspects, since the fixing tool is constituted by a bolt (30 or 40), the moving mechanism is moved. The mirror can be easily and reliably fixed to the measurement object.

According to a fifth aspect of the present invention, in the moving mirror supporting mechanism according to the fourth aspect, the bolt (30 or 4) is provided.
0) and the movable mirror (10), a sliding member (46) for reducing the rotational torque applied to the movable mirror (10) from the bolt (30 or 40) when tightening the bolt (30 or 40). ) Is interposed.

When the movable mirror is fastened and fixed by bolts, the large diameter portion of the bolt is rotated to screw a rod-shaped member having an external thread formed on the outer periphery into a screw hole, and the upper surface of the movable mirror and the large bolt are used. Tightening is completed when the friction increases due to the contact with the diameter part, but the force that twists the moving mirror in the direction of rotation of the bolt from the moment when the moving mirror comes into contact with the bolt until the tightening is completed. (Rotational torque). In this case, since the sliding member for reducing the rotational torque is interposed between the bolt and the movable mirror, the stress generated in the movable mirror by tightening the bolt can be reduced, and the measurement surface (reflection surface) of the movable mirror Can be suppressed as much as possible.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to fourth embodiments of the movable mirror support mechanism according to the present invention will be described with reference to FIGS.

<< First Embodiment >> FIG. 1 shows the configuration of a movable mirror support mechanism according to a first embodiment. FIG.
In the upper surface of the band-shaped convex portion 14 having a predetermined width formed at one end on the stage 12 as a measurement target, a rectangular convex in a plan view is provided at a position spaced at a predetermined interval along the longitudinal direction. Bottom support surfaces 16A and 16B are provided as two movable mirror mounting surfaces each composed of a portion. Moving mirror 10
Are horizontally supported by these bottom support surfaces 16A and 16B. Two mounting holes 18A and 18B are formed in the upper surface portion of the movable mirror 10, and bolts 30 (however, a fixing tool) are provided in the mounting holes 18A and 18B.
The bolts in the mounting holes 18B are not shown in FIG.
Are inserted, and the bottom support surfaces 16A, 16A on the stage 12 are inserted.
B is screwed and fixed to a screw hole 34 formed in B.

On one end face (right end face in FIG. 1) of the movable mirror 10, there is provided a reflection surface 20 as a measurement surface for receiving and reflecting laser light emitted from a laser interferometer (not shown) in a measurement direction (in the figure). It is formed so as to extend in a direction orthogonal to the direction of arrow A). The reflection surface 20 is formed by depositing silver or the like on the measurement end surface side of the movable mirror 10 which is a glass body having a rectangular cross section.

The reflecting surface 20 of the movable mirror 10 shown in FIG.
Is a use area 22A used for incident and reflection of laser light from a laser interferometer when the stage 12 moves on a plane.
And a non-use area 22B in which a reflection surface is formed but not used for measurement. (In FIG. 1, the non-use area 22B is drawn with sand for convenience of explanation. Reference numeral 22B denotes a reflection surface on which silver or the like is vapor-deposited similarly to the use area, and there is no boundary between the use area 22A and the non-use area 22B.) In the first embodiment, the aforementioned mounting holes 18A and 18B are provided at positions corresponding to the non-use area 22B of the reflection surface 20, and the movable mirror 10 is fixed to the stage 12 by bolts 30 at that position.

The stage 12 projects a circuit pattern formed on a mask (or reticle) in a lithography process for manufacturing a semiconductor element or the like on a photosensitive substrate (a wafer or the like) coated with a resist or the like via a projection optical system. Is a wafer stage of a reduction projection exposure apparatus (a so-called stepper). In this stepper, the exposure process is sequentially performed while the stage 12 is being moved stepwise. Therefore, when the stage 12 starts moving or stops (at the time of the exposure process), the movable mirror 1 is moved.
Since a force due to the drive acceleration acts on 0, it is required that the movable mirror be supported so as not to be displaced. The laser beam from a laser interferometer (not shown) is incident on and reflected from the reflecting surface 20 of the movable mirror 10 fixed on the stage 12, so that the coordinate position of the wafer stage, that is, the stage 12, is super-precise. (In units of 0.01 μm).

According to the moving mirror support mechanism of the first embodiment configured as described above, the moving mirror 10 has two mounting holes 18A and 18B formed on the upper surface thereof.
The movable mirror 10 can be securely fixed on the stage 12 by being screwed and fixed to the screw holes 34 formed in the bottom surface supporting surfaces 16A and 16B on the stage 12 side with the bolt 30 via. For this reason, when the stage 12 is driven and moved stepwise, even if a force due to the drive acceleration acts on the movable mirror 10, the movable mirror 10 does not displace, and the laser interferometer can perform highly accurate position measurement. It became so. In particular, since the movable mirror is fixed at two or more places by the fixture (here, bolts), the movable mirror 10 is fixed.
Can be prevented from being displaced due to the rotation of.

In the first embodiment, the movable mirror 10
Area other than the use area 22A of the reflective surface 20 (here,
Since the movable mirror 10 is fixed by using the bolt 30 at a position corresponding to the non-use area 22B), even if the movable mirror 10 is stressed due to the force applied to the movable mirror 10 when tightened with the bolt 30, the reflection is reflected. The distortion of the surface 20 is reduced to the unused area 22B.
, And does not reach the use area 22A.

<< Second Embodiment >> FIG. 2 shows the configuration of a moving mirror support mechanism according to a second embodiment. FIG.
Here, the same or equivalent components as those in FIG. 1 showing the movable mirror support mechanism of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 2, the movable mirror supporting mechanism according to the second embodiment
The two bottom support surfaces 32A and 32B are formed as movable mirror mounting surfaces that support 0 in the direction of gravity, and the shapes of the bottom support surfaces 32A and 32B are changed from both ends in the measurement direction indicated by arrow A in the figure. It is characterized in that it is formed in a convex shape so that its height gradually increases toward the center.

FIG. 3 shows a cross section at the position of the bolt 30 in FIG. 2 to explain the shape of the one bottom support surface 32A more easily. As shown in FIG.
The top surface of the bottom support surface 32A facing the bottom surface of the movable mirror 10 has the lowest position corresponding to both ends of the movable mirror 10 in the measurement direction indicated by the arrow A in the figure.
The convex surface 36 is formed such that the height gradually increases toward the central portion where 4 is formed.

Here, the configuration of the moving mirror support mechanism shown in FIG. 3 will be described. At a fixing position where the movable mirror 10 is fixed with a fixing tool, a bolt mounting hole 18A having a circular shape in a plan view is formed to the middle, and a central portion of a bottom surface 38 of the mounting hole 18A has a smaller diameter. Through hole 19 is formed downward (the other mounting hole 18B is also formed in the depth direction of the paper surface with the same configuration). On the side of the stage 12 that supports the movable mirror 10, two bottom support surfaces 32 </ b> A that support the movable mirror 10 on the upper surface of the convex portion 14 formed at one end of the stage 12 (however, in the depth direction of the paper surface). The formed bottom support surface 32B is not shown), and the bottom support surface 32B is formed.
At approximately the middle position in the measurement direction A (arrow A) of A (32B), there is formed a screw hole 34 in which a female screw is screwed to be screwed with the rod portion 30B of the bolt 30. Further, a bolt 30 as a fixing tool has a head 30A having a large diameter portion and a head 30A.
A small-diameter rod-shaped portion 30B integrally formed below A and having an outer peripheral portion threaded.

In the above-described movable mirror 10, the movable mirror 12 is mounted on the bottom support surface 32A (32B) of the stage 12,
Screw hole 34 of bottom support surface 32A (32B) and movable mirror 10
Is fixed to the stage 12 by inserting the bolt 30 into the mounting hole 18A of the movable mirror 10 and screwing the rod-shaped portion 30B into the screw hole 34 and tightening.

As described above, when the movable mirror 10 is fixed on the stage 12 with the bolts 30, the center of the movable mirror 10 made of a low-rigidity glass member or the like is placed on the stage 12 made of a high-rigidity metal member or the like. When the area is tightened with bolts 30 and compressed, the measurement direction of the movable mirror 10 (arrow A direction)
Stress deformation that extends in the vertical direction occurs at both ends. At this time, when the bottom support surface has a planar shape (conventional example), the force of the movable mirror 10 deformed in the direction shown by arrow B in FIG. 3 is applied to this bottom support surface, but the bottom support surface made of metal is applied. Since the side hardly deforms, the movable mirror 10
The side may receive the reaction force (indicated by the white arrow C) and distort the reflecting surface 20 of the movable mirror 10.

On the other hand, according to the movable mirror support mechanism of the second embodiment, since the upper surface of the bottom support surface 32A is a convex surface 36 (see FIG. 3), the movable mirror 10 can be moved. Even if stress is deformed in the direction of arrow B, there is a gap between the movable mirror 10 and the bottom support surface 32A, so that the deformation of the movable mirror 10 is not hindered, and the movable mirror 10 receives a reaction force (arrow C) from the bottom support surface 32A. And the reflecting surface 20 of the movable mirror 10
Can be prevented from being distorted.

The degree of curvature of the convex surface 36 of the bottom support surface 32A (32B) shown in FIG. 3 is greatly bent for easy understanding. The deformation amount itself is very small, and the convex surface 36 is actually formed by a curved surface according to the deformation amount.

<< Third Embodiment >> FIG. 4 shows the configuration of a moving mirror support mechanism according to a third embodiment. In FIG. 4, the same or equivalent components as those in FIGS. 1 to 3 described above are denoted by the same reference numerals and description thereof will be omitted.

In the third embodiment, as shown in FIG. 4, between the head 30A of the bolt 30 and the bottom 38 of the mounting hole 18A, the head 30A of the bolt 30
It is characterized in that a sliding plate 46 for reducing the rotational torque applied to the motor is arranged.

Here, the sliding member 46 has a donut-shaped flat plate shape such as a washer, and is formed by using a resin or the like (for example, Teflon) that reduces the friction coefficient. Bolt 3
As a member for reducing the friction between the movable mirror 10 and the bottom surface 38 of the movable mirror 10, for example, a member obtained by applying a lubricating oil to a metal plate or a member obtained by laminating a plurality of thin-film sheets which are easily slipped on each other is used. The member 46 may be interposed.

According to the moving mirror support mechanism described above, as shown in FIG. 4, when the bolt 30 is fastened while rotating the bolt 30 in the right direction (the tightening direction indicated by the arrow D), the bolt 30 is fixed. The head 30A is tightened while rubbing the bottom surface 38 of the movable mirror 10 via the sliding plate 46, so that the friction between the head 30A and the bottom surface 38 can be greatly reduced. That is, the effect of reducing the frictional force by the sliding plate 46 between the head 30A and the bottom surface 38 is that the rotation applied to the bottom surface 38 of the movable mirror when the bolt 30 is rotated in the tightening direction (the direction of arrow D). The torque can be significantly reduced.

Therefore, when the slide plate 46 is interposed between the bolt 30 and the movable mirror 10 and fixed to the stage 12, the rotational torque applied to the movable mirror 10 when tightening with the bolt 30 is greatly reduced. In addition, the deformation of the movable mirror 10 in the torsional direction (the direction of the arrow D) is reduced, so that it is possible to prevent the reflective surface from being distorted.

<< Fourth Embodiment >> FIG. 5 shows a case where the bottom of the mounting hole of the movable mirror is inclined and fixed using ordinary bolts. FIG. The configuration of the moving mirror support mechanism according to the fourth embodiment is shown. In FIGS. 5 and 6, the same or equivalent components as those in FIGS. 1 to 4 described above are denoted by the same reference numerals and description thereof is omitted.

First, as shown in FIG. 6, the movable mirror support mechanism of the fourth embodiment has a mounting hole 1 for the movable mirror 10.
Even when the bottom surface 38 of the bolt 8A is inclined, the spherical projection 48 is provided between the head 30A of the bolt 30 and the bottom surface 38 so that the head 30A of the bolt 30 does not hit against the bottom surface 38.
And the spherical concave portion 47 are opposed to each other. The spherical projection 48 is formed around the rod 30B directly below the head 30A of the bolt 30, and is a member having a spherical surface that gradually projects toward the bottom surface 38 from the periphery to the central rod 30B. is there. The spherical concave portion 47 is formed around the rod portion 30B of the bolt 30 at a position facing the above-mentioned spherical convex portion 48, and extends from the peripheral portion to the central rod portion 3B.
It is a member in which a depression is gradually formed toward 0B. The spherical convex portion 48 and the spherical concave portion 47 are tightened with the bolt 30 in a state where the opposing convex portion and concave portion are in contact with each other, so that even if the bolt 30 or the bottom surface 38 is inclined, the contact position between the spherical surfaces is reduced. It is moved as appropriate to prevent the one-sided contact, and the tightening force of the bolt is dispersed to the bottom surface 38 side so that stress concentration does not occur.

For example, as shown in FIG. 5, when the bottom surface 38 of the mounting hole 18A of the movable mirror 10 is inclined as shown in FIG. When the movable mirror 10 is tightened and fixed using the bolts 30), the edge of the head 30A of the bolt 30 is in contact with a part of the inclined bottom surface 38. On the bottom surface 38 against which the bolt has one side, the tightening force of the bolt 30 (the direction in which the force is applied is indicated by an arrow E in FIG. 5).
Are concentrated in the moving mirror 10, and a biased stress is generated in the movable mirror 10, and the position where the stress is generated may be near the reflection surface 20 of the movable mirror 10 depending on the tilt direction (in the case of FIG. 5). ), It is necessary to consider the influence of distortion on the reflection surface 20.

For this reason, the movable mirror supporting mechanism according to the fourth embodiment has the above-described structure for preventing the one-sided contact of the bolt, and in addition to the structure, the first to third embodiments described above. It is configured to incorporate all the features of the moving mirror support mechanism according to the embodiment.

That is, the movable mirror 10 shown in FIG.
The bottom support surface 3 on the stage 12 side using two bolts 30 (the other one is provided in the depth direction of the drawing and not shown).
2A (32B is also provided in the depth direction of the drawing and is not shown), is screwed into a screw hole 34 formed therein, and is tightened and fixed. Although not shown in FIG. 6,
The fixing position where the movable mirror 10 is fixed with the bolt 30 is the same as that in FIG. 1, and is provided at a position corresponding to a region other than the use region 22A of the reflection surface 20 (here, the non-use region 22B). (Similar to the first embodiment).

In the fourth embodiment, the movable mirror 10 shown in FIG. 6 is moved to a position at a predetermined interval on the upper surface of the convex portion 14 formed at one end of the stage 12 in the direction of gravity. Two bottom support surfaces 32A as mirror mounting surfaces
(32B) is formed and is horizontally supported by this. The shape of the bottom support surface 32A (32B) corresponds to the moving mirror 1 shown in the measurement direction (the direction of arrow A) of the laser interferometer.
0 is formed on the convex surface 36 such that the height gradually increases from both end portions to the center portion (second surface).
As in the embodiment).

Further, in the fourth embodiment, the bottom surface 3 of the mounting hole 18A formed in the movable mirror 10 shown in FIG.
A sliding plate 46 for reducing the frictional force between the bolt 8 and the head 30A of the bolt 30 is interposed (similar to the third embodiment).

As described above, the moving mirror support mechanism of the fourth embodiment incorporates the characteristic configurations of the above-described first to third embodiments in addition to the characteristic configuration of the fourth embodiment. Therefore, it is possible to obtain a suitable effect in which the effects of these components are superimposed.

Specifically, the moving mirror supporting mechanism of the fourth embodiment shown in FIG. The movable mirror 10 is moved to the stage 1 using the bolts 30.
2, the displacement of the movable mirror 10 can be reliably prevented. In addition, the position where the movable mirror 10 is fixed by the bolt 30 is a position corresponding to an area other than the use area 22A of the reflection surface 20 of the movable mirror 10 (see FIG. 1). Even if the deformation occurs, the distortion generated on the reflection surface 20 is changed to the unused area 22B.
, And does not reach the use area 22A.

In the fourth embodiment, when the movable mirror 10 is securely fixed to the stage 12 by using bolts 30 or the like, both ends of the movable mirror 10 in the measurement direction (the direction of the arrow A) are fixed. Although it may be deformed so as to extend in the vertical direction, the bottom support surface 32A (32
By making the shape of B) the convex surface 36, the movable mirror 10
Since there is no bottom support surface 32A (32B) at the position where the deformation of the reflective surface 20 is prevented, secondary stress due to the reaction force is not generated, and it is possible to prevent the reflective surface 20 from being distorted.

Further, in the fourth embodiment, the movable mirror 1
Since the sliding plate 46 made of resin or the like for reducing the frictional force between the two is interposed between the bottom surface 38 of the mounting hole 18A formed at 0 and the spherical concave portion 47, the bottom support surface 32A using the bolt 30 is used. When the movable mirror 10 is tightened and fixed, the rotational moment applied from the bolt 30 to the bottom surface 38 of the movable mirror 10 can be greatly reduced. As an effect of reducing the rotational moment, it is possible to prevent the stress generated in the movable mirror 10 from being reduced, thereby preventing the reflection surface 20 from being distorted.

Also, as shown in FIG.
The spherical concave portion 47 and the spherical convex portion 48 are opposed to each other between the bolt 30 and the head 30A of the bolt 30, so that the bottom surface 38 is inclined or the screw hole 34 is formed in a direction perpendicular to the bottom surface 32A. Even if the bolt is inclined and screwed into place, the contact position of the spherical concave portion 47 and the spherical convex portion 48 is changed in accordance with the inclination of the concave portion 47 and the one-side contact is prevented, so that the reflection surface 20 of the movable mirror 10 is prevented. Can be prevented from being distorted.

Next, another embodiment of the above-described fourth embodiment will be described. The moving mirror support mechanism shown in FIG. 7 has a simple configuration to prevent the one-side contact even if the bottom surface 38 of the mounting hole 18A of the moving mirror 10 is inclined. Specifically, the opposing surface 42 side of the head 40A of the bolt 40 opposing the bottom surface 38 of the mounting hole 18A of the movable mirror 10 gradually projects toward the bottom surface 38 from the peripheral portion to the central portion of the rod portion 40B. The feature is that a bolt formed in a spherical shape is used.

As described above, since the facing surface 42 of the head 40A of the bolt 40 has a spherical shape, when the bolt 40 is tightened while the bottom surface 38 of the mounting hole 18A of the movable mirror 10 is inclined, the bottom surface 38 is always Head 40 near screw hole 34
A and the vicinity of the boundary between the bar-shaped portion 40B and the head 40A
Can be prevented from hitting against the bottom surface 38. As a result, it is possible to prevent the reflection surface 20 of the movable mirror 10 from being distorted.

As described above, according to the moving mirror support mechanism of the first to fourth embodiments, the displacement of the movable mirror is prevented by securely fixing the movable mirror, and the movable mirror is fixed when the movable mirror is fixed. When the clamping force is applied to the moving mirror, the movable mirror is not deformed as much as possible, and even if it is deformed, the reflection surface is prevented from being deformed as much as possible. It can be performed with high accuracy.

In the above embodiment, the movable mirror and the stage are fixed by using two fixtures.
It may be fixed by one or more fixing devices. In this case, it is preferable that the fixed position is a position corresponding to an area other than the use area of the reflecting surface of the movable mirror.

In the above embodiment, the bolt is used as the fixing tool. However, the present invention is not limited to this, and the fixing tool may be fixed using a rivet or the like.

Further, in the above-described embodiment, the sliding plate is interposed between the bolt and the movable mirror, so that when the bolt is tightened and the movable mirror is fixed, the rotational torque applied to the movable mirror from the bolt is reduced. However, the present invention is not limited to this, and at least one of the contact surfaces between the bolt and the movable mirror may be coated or coated with a sliding film for reducing the coefficient of friction or a lubricant.

In the fourth embodiment, as shown in FIG. 7, the spherical concave portion 47 and the spherical convex portion 48 are arranged between the bolt and the movable mirror so as to face each other. In the case of a resin member having a small coefficient, the sliding plate 4
6 can also be omitted.

In the other embodiment of the fourth embodiment, the opposing surface 42 of the head 40A of the bolt 40 is formed in a spherical shape. However, the present invention is not limited to this. It may be formed in a shape.

Further, in the above embodiment, the present invention is applied to the exposure apparatus of the step-and-repeat method, but the scope of the present invention is not limited to this, and the step-and-scan method, other It is also possible to apply the present invention not only to the exposure apparatus, but also to general apparatuses that perform position measurement using an interferometer.

[0060]

As described above, according to the present invention,
By securely fixing the movable mirror, it is possible to prevent the displacement of the movable mirror on the object to be measured, and the stress generated in the movable mirror when the movable mirror is securely fixed causes the movable mirror itself to be displaced. Even if it is deformed, there is an unprecedented excellent effect that distortion of the reflecting surface due to the deformation can be suppressed as much as possible.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing a movable mirror support mechanism according to a first embodiment.

FIG. 2 is a partially broken perspective view showing a movable mirror support mechanism according to a second embodiment.

FIG. 3 is an enlarged sectional view of a movable mirror in the movable mirror support mechanism of FIG.

FIG. 4 is a perspective view showing a main part of a movable mirror supporting mechanism according to a third embodiment, partially cut away;

FIG. 5 is a cross-sectional view of the movable mirror for explaining a state in which a bolt hits one side.

FIG. 6 is a schematic sectional view of a main part of a moving mirror support mechanism according to a fourth embodiment.

FIG. 7 is a schematic sectional view of a main part of a moving mirror support mechanism according to another embodiment of the fourth embodiment.

FIG. 8 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Moving mirror 12 Stage 16A, 16B Bottom support surface 20 Reflection surface 30 Bolt 30A Head 30B Rod part 32A, 32B Bottom support surface 38 Bottom 40 Bolt 40A Head 40B Rod part 42 Opposite surface 46 Sliding plate

Claims (5)

[Claims] 1. A moving mirror support mechanism for supporting a movable mirror having a rectangular cross section that constitutes a part of an interferometer on a measuring object at right angles to a measuring direction, wherein the moving mirror is mounted on the measuring object from above. At least two fixtures respectively fixed to the upper movable mirror mounting surface, and a fixed position for fixing the movable mirror on the measurement object using the fixture is outside a range of use of the measurement surface of the movable mirror. A movable mirror support mechanism provided on the movable mirror. 2. A moving mirror support mechanism for supporting a movable mirror having a rectangular cross section which constitutes a part of an interferometer on a measuring object at right angles to a measuring direction, wherein the measuring direction is provided on the measuring object. At least two convex surfaces are arranged at predetermined intervals along a direction orthogonal to the upper surface, and the upper surface thereof has at least two convex surfaces whose height gradually increases from both ends in the measurement direction toward the center. A moving mirror support mechanism comprising: a moving mirror mounting surface; and a plurality of fixtures for fixing the moving mirror on the measurement object from above at the positions of the at least two moving mirror mounting surfaces. 3. A moving mirror supporting mechanism for supporting a movable mirror having a rectangular cross section that forms a part of an interferometer on a measurement object at right angles to a measurement direction, wherein the movement mirror is mounted on the measurement object from above. At least two fixtures each including a rod-shaped member for fixing to the upper movable mirror mounting surface and a large-diameter portion provided at one end of the rod-shaped member, and the fixture opposed to the upper surface of the movable mirror A movable mirror supporting mechanism, wherein a surface of the large diameter portion is formed in a spherical shape so as to gradually protrude toward the upper surface of the movable mirror from a peripheral portion to a central portion of the rod-shaped member. 4. The moving mirror support mechanism according to claim 1, wherein the fixing tool is a bolt. 5. A sliding member interposed between the bolt and the movable mirror for reducing a rotational torque applied to the movable mirror from the bolt when the bolt is tightened. 3. The moving mirror support mechanism according to claim 1.