JPH0735963A - Position adjusting device for optical device - Google Patents

Abstract

PURPOSE:To dispense with the exchange of a washer and to perform the adjustment of three axes easily and in a short time in the position adjustment of an optical device which comprises an optical system. CONSTITUTION:A holding member 3 which holds the optical device M is arranged on a movable member 2 provided with a placing plane 2A inclined to a prescribed reference plane. Also, fixing members (4a-4d, 5a-5d) can be switched to a first state where the movable member 2 and the holding member 3 are fixed integrally and a second state where they can be moved relatively. First driving means(6, 23c) drive the movable member 2 in a prescribed direction within the reference plane when the second state is set, and second driving means (7, 8, 23a, 23b) drive the holding member 3 in the prescribed direction within the reference plane when the first state is set, and also, supply a prescribed pressing force to the holding member 3 so as to move the holding member 3 only in a direction perpendicular to the reference plane when the first driving means (6, 23c) drive the movable member 2 in the prescribed direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for adjusting the position of an optical element (for example, a lens, a mirror, etc.), and more particularly to the position of the optical element in a projection optical system in a projection exposure apparatus with respect to the optical axis of the projection optical system. The present invention relates to a position adjusting device that moves.

[0002]

2. Description of the Related Art In a projection exposure apparatus for manufacturing a semiconductor element, a transmitted light flux of a mask pattern is imaged on a photosensitive substrate (wafer) on a stage via a projection optical system. The projection optical system includes a refraction system, a reflection system, or a catadioptric system that is a combination of both, and is composed of a plurality of optical elements (lens, mirror, concave mirror, etc.). Since this type of projection optical system needs to project and image a fine pattern on a wafer with high resolution, individual optical elements are assembled and adjusted with extremely high precision in the manufacturing thereof, and sophisticated aberration correction is also performed. Has been done. However, various aberrations (for example, field curvature, coma aberration, astigmatism, etc.) may largely remain due to the manufacturing accuracy, assembly accuracy, and the like of the optical element.

For example, in a projection optical system in which field curvature remains, it becomes difficult to make the entire surface of one shot area on the wafer coincide with the image plane of the projection optical system, or to set it within the depth of focus. Poor resolution will occur. However, various aberrations of the projection optical system can be suppressed to some extent by finely adjusting the positions of one or a plurality of optical elements that form the projection optical system.
Therefore, a mechanism for finely adjusting the position is provided for the optical element in the projection optical system, particularly for the optical element at the position (position) where the effect of suppressing the occurrence of each aberration is greatest.

Conventionally, in order to adjust the position of the optical element with respect to the optical axis of the projection optical system, a gap is adjusted between a holding member for holding the optical element and a base (for example, a part of a lens barrel of the projection optical system). A plate (washer) was placed, and the washer was replaced with a washer having a different thickness depending on the type and magnitude of aberration occurring in the projection optical system. A driving element such as a piezo element may be used instead of the washer. This is at least 3 between the holding member holding the optical element and the base.
A drive element is arranged at some place. Then, each drive element is expanded / contracted by changing the voltage applied to each drive element to adjust the position and inclination of the optical element.

[0005]

However, in the prior art as described above, a plurality of washers having different thicknesses must be prepared, or one washer must be processed to adjust the position of the optical element while changing the thickness. I have to. If multiple washers are prepared, the cost will be significantly high, and the adjustment during processing will be time-consuming.
Furthermore, since the required processing accuracy of the washer is extremely severe, a skilled technique for processing the washer is also required.

Further, the above-mentioned position adjustment by the washer and the drive element is targeted only in the Z-axis direction, and the adjustment in the directions substantially perpendicular to the Z-axis (XY directions) cannot be performed. Therefore, in order to adjust one optical element in three axes (X, Y, Z), an adjustment mechanism in the XY directions must be provided, and the device becomes complicated and large. The present invention has been made in view of the above problems, and in the position adjustment of the optical element in the projection optical system, it is not necessary to replace the washer, and the triaxial adjustment can be easily performed in a short time. An object of the present invention is to provide a position adjusting device that can be used.

[0007]

In order to make the present invention easier to understand, the present invention will be described with reference to FIG. 1 which is an embodiment. In order to solve such a problem, according to the present invention, an optical element (M) that constitutes an optical system is finely moved to adjust the position of the optical element (M) with respect to the optical axis (AX) of the optical system. Of the movable member (2), which has a mounting surface (2A) tilted with respect to the reference plane and is movable on the movable member (2) while moving two-dimensionally within the reference plane of the optical element (M). Is provided on at least one of the movable member (2) and the holding member (3) that holds the substrate and is movable along the mounting surface (2A), and the movable member (2) and the holding member. (3) and a fixing member (5a to 5d) for switching between a first state in which they are integrally fixed and a second state in which they are relatively movable.

Further, a first driving means (6, 23c) for driving the movable member (2) in a predetermined direction (Y direction) in the above-mentioned second state, and a holding member (in the above-mentioned first state). 3) is driven in a predetermined direction (XY direction) within the reference plane, and when the first driving means (6, 23c) drives the movable member (2) in a predetermined direction (Y direction), the holding member (3). So as to move only in the direction (Z direction) perpendicular to the reference plane, the second drive means (7, 8, 23a, 23b) for restricting the movement of the holding member (3) in the reference plane direction. .

[0009]

When the position of the optical element in the projection optical system is two-dimensionally moved within a predetermined reference plane, first, the movable member and the holding member are integrally fixed by the fixed member. Then, the holding member is moved in the predetermined direction within the reference plane by the second driving means. Since the holding member and the movable member are fixed,
Both move two-dimensionally within the reference plane. Therefore, the optical element also moves two-dimensionally within the reference plane.

Further, when the position of the optical element is moved in a direction substantially perpendicular to the reference plane, the fixed member switches to a state in which the movable member and the holding member are relatively movable. Then, the first driving means moves the movable member in a predetermined direction within the reference plane. Here, the inclination angle of the mounting surface of the movable member with respect to the reference plane is θ, and the direction in which the movable member is moved by the first driving means is a direction in which the mounting surface of the movable member forms an angle θ with respect to the reference plane. .

For example, assume that the movable member is moved by the distance x in the above-mentioned direction. Since the second driving means limits the movement of the holding member in the reference plane direction, the holding member moves only in the direction perpendicular to the reference plane. Therefore, when the movable member moves by the distance x as described above, the holding member moves by the distance xtan θ along the inclined surface of the movable member in the direction perpendicular to the reference plane.

By operating the position adjusting device in this manner, it becomes possible to adjust the optical element in the projection optical system in the reference plane direction and in the direction perpendicular to the reference plane.

[0013]

1 is a diagram showing a schematic configuration of a position adjusting device according to an embodiment of the present invention. In this embodiment, a projection optical system suitable for a projection exposure apparatus, for example, Japanese Patent Laid-Open No. 3-285272.
The present invention is applied to a concave mirror among a plurality of optical elements constituting the catadioptric reduction projection optical system disclosed in Japanese Patent Laid-Open Publication No. A description will be given below with reference to FIG.

The concave mirror M is one optical element in the projection optical system, and illustration of optical elements other than the mirror M is omitted. Further, FIG. 1A is a top view of the apparatus when viewed from above (the mirror M side), and FIG. 1B is a side view of the apparatus when viewed from the side. As shown in FIG. 1 (b),
The optical axis AX of the projection optical system of this apparatus is substantially parallel to the Z-axis direction in the XYZ coordinate system. A plane substantially perpendicular to the optical axis AX is defined as an XY plane (reference plane).

The base 1 is a reference plane 1 substantially parallel to the reference plane.
A, and a movable member (spacing adjustment ring) on this reference plane 1A
2 is placed. The spacing adjusting ring 2 has a wedge shape so that the upper surface (mounting surface) 2A has a predetermined inclination angle θ with respect to the lower surface 2B. In this embodiment, the inclination angle θ is 10% (about 5%). 7 degrees). And FIG. 1 (b)
As shown in FIG. 5, the base 1 is arranged so that the inclination in the Y direction is maximized. A holding member 3 that holds the concave mirror M is placed on the space adjusting ring 2. Holding member 3
3A is a plane substantially perpendicular to the optical axis MX of the mirror M. Therefore, the optical axis MX of the mirror M is the optical axis AX of the projection optical system.
In contrast to the inclination angle θ of the interval adjusting ring 2 described above, 10%
Leaning.

The interval adjusting ring 2 and the holding member 3 are each cylindrical, and as shown in FIG. 1B, the diameter (diameter) of the lower cylinder of each member is larger than the diameter of the upper cylinder, and the cross section is L. It has a glyph. The lower portion of the gap adjusting ring 2 and the base 1 are connected by bolts 4a to 4d. Figure 1 (a)
As shown in FIG. 5, the bolts 4a to 4d are arranged at positions rotated by 90 ° each, and are inclined by 45 ° with respect to the X axis and the Y axis. Similarly, the lower portion of the holding member 3 and the gap adjusting ring 2 are connected by bolts 5a to 5d, and the bolts 5a to 5d are arranged at positions rotated by 90 ° each, and the bolts 5a to 5d are rotated 45 ° with respect to the X axis and the Y axis, respectively. ° tilted.

Further, as shown in FIG. 1B, since the exposure light is applied to the mirror M from the lower side (base 1 side), each of the base 1, the gap adjusting ring 2 and the holding member 3 is exposed. Are provided with circular openings 1H, 2H, 3H having a size (diameter) that does not block the exposure light irradiation area. A drive member (actuator) 6 is fixed to the base 1, and actuators 7 and 8 are held by support members 9 and 10 fixed to the base 1, respectively. The tip portion 6A of the actuator 6 is in contact with the outer peripheral portion of the space adjusting ring 2,
Each is connected by an elastic member (spring) 23c.
Similarly, the tip portions 7A and 8A of the actuators 7 and 8 are also in contact with the outer peripheral portion of the holding member, and the springs 23a and 23b.
Are connected by each. And actuator 6
When the adjusting knob portion 6B is rotated, the actuator 6
6A has a mechanism such that the tip end portion 6A thereof moves in the Y direction, and the interval adjusting ring 2 can be moved in the Y direction.
Similarly, the actuators 7 and 8 also have such a mechanism that when the tips 7B and 8B are rotated, the tips 7A and 8A move in the Y and X directions, respectively, and the holding member 3 is moved in the XY directions. You can These detailed configurations will be described below with reference to FIG.

FIG. 2 is a partial sectional view showing a schematic structure of a portion where the actuator 7 and the holding member 3 are in contact with each other. The actuator 6, the gap adjusting ring 2 and the actuator 8 are shown.
The portion where the holding member 3 contacts with the holding member 3 has the same configuration. Further, in FIG. 2, a connecting portion of a bolt connecting the holding member 3 and the gap adjusting ring 2 is shown in a sectional view. The drive mechanism for the gap adjusting ring 2 and the holding member 3 will be described below with reference to FIGS. 1 and 2. In FIG. 2, the same members as those in FIG. 1 are designated by the same reference numerals.

The male screw of the bolt 5d is screwed with the female screw 25 provided on the gap adjusting ring 2, and the holding member 3 has a circular opening 26 having a diameter larger than that of the male screw of the bolt 5d.
Is provided. The other bolts 5a to 5c connecting the space adjusting ring 2 and the holding member 3 have the same structure, and the bolts 4a to 4d connecting the space adjusting ring 2 to the base 1 also have the same structure. It is a composition. Therefore, the male screws of the bolts 5a to 5d are attached to the space adjusting ring 2 by 4
Even if the holding members 3 are not completely removed from the two female screws, the holding members 3 and the distance adjusting rings 2 are relatively moved by loosening the holding members 3 by the heads of the bolts 5a to 5d to such an extent that there is no force to press them against the distance adjusting rings 2. A small amount (within the range of the difference between the diameter of the circular opening provided on the holding member 3 and the diameter of the male screw of the bolts 5a to 5d) can be moved. Bolt 4 as well
By slightly loosening the male screws a to 4d, the gap adjusting ring 2 and the base 1 can be moved by a relatively small amount.

A stopper 21 is fixed to the tip portion 7A of the actuator 7, and a stopper 22 is fixed to the holding member 3 as well. And each stop 21,
22 are connected by an elastic member (spring) 23a. An address piece 24 is provided on the end surface of the holding member 3, and the tip of the address piece 24 has a hemispherical shape. The tip end of the contact piece 24 and the end face of the tip end 7A of the actuator 7 are in contact with each other, and the springs 23a exert a force to attract each other. The actuator 7 can move the tip portion 7A in the Y direction by rotating the adjusting knob 7B shown in FIG. Here, the tip portion 7A is moved to the right in FIG. 2 (the holding member 3 by the adjusting knob 7B).
When it is moved to the side), the holding member 3 can be moved in the same direction via the address piece 24. Adjustment knob 7B
When the tip portion 7A is moved leftward in FIG. 2 (on the side of the support member 9) by means of, the holding member 3 can be moved in the same direction by the elastic force of the spring 23a. Since the tip portion 7A does not move unless the adjusting knob 7B is rotated, the tip portion 7A
On the other hand, even if some external force is applied in the Y direction, the tip portion 7A does not move in the Y direction by the external force. Further, the spring 23a brings the tip end portion of the contact piece 24 and the tip end portion 7A of the actuator 7 into contact with each other by a high expansion and contraction force.
Therefore, the space adjusting ring 2 is moved in the Y direction to move the holding member 3
When slightly moving in the Z direction, the holding member 3 is always given a predetermined urging force in the direction opposite to the moving direction of the distance adjusting ring 2 by the actuator 7 and the spring 23a, so that the holding member does not shift in the Y direction. . This also applies to the X direction.

Next, the operation of moving the holding member 3 in the X direction and the Y direction (within the reference plane), that is, the position of the mirror M is changed to the X direction.
The operation for adjusting the direction and the Y direction will be described. First, the bolts 4a to 4d are loosened to such an extent that the distance adjusting ring 2 can move on the base 1, and the holding member 3 and the distance adjusting ring 2 are coupled by the bolts 5a to 5d, so that both can move integrally ( 1st state). Then, the holding member 3 is moved by the actuators 7 and 8. Since the holding member 3 and the gap adjusting ring 2 are connected by the bolts, both of them move integrally on the base 1. Since the reference plane 1A of the base 1 is substantially parallel to the reference plane (XY plane), the position of the mirror M can be moved in the XY plane, that is, the direction substantially perpendicular to the optical axis AX of the projection optical system by the above operation. it can.

At this time, since the actuator 6 suppresses the movement of the gap adjusting ring 2 in the Y direction, the actuator 6 is detached from the base 1 before adjusting the position of the mirror M in the XY directions. Further, a mechanism may be provided so that the tip portion 6A can be switched so as to be movable in the Y direction according to an external force applied to the tip portion 6A (a force applied to the tip portion 6A by the movement of the interval adjusting ring 2 in the Y direction).

Next, the operation for moving the holding member 3 in the Z direction, that is, the operation for adjusting the position of the mirror M in the Z direction will be described. First, the bolts 4a to 4d and 5a to
All of 5d are loosened so that the base 1 and the gap adjusting ring 2, and the gap adjusting ring 2 and the holding member 3 can move relative to each other (second state). Then, the actuator 6 moves the distance adjusting ring 2 on the base 1 by a small amount. At this time, the holding member 3 is prevented from moving in the Y direction by each of the actuator 7 and the spring 23, and is also prevented from moving in the X direction. Therefore, the holding member 3 moves in the Z-axis direction along the mounting surface 2A of the gap adjusting ring 2. With the above operation, the mirror M can be moved in the Z-axis direction, that is, in the direction substantially parallel to the optical axis of the projection optical system. Since the inclination angle of the mounting surface 2A with respect to the reference plane is 10%, the movement amount of the mirror M in the Z-axis direction is reduced to 1/10 when the movement amount of the interval adjusting ring 2 is 1. That is, when the distance adjusting ring 2 is moved 0.1 mm in the Y-axis direction, the mirror M is moved 10 μm in the Z-axis direction.

In this embodiment, the mirror M is first moved in the XY directions and then moved in the Z direction, but either one may be adjusted first. Further, the fixing member is not limited to the bolt,
A mechanism may be used in which the holding member 3 and the gap adjusting ring 2 (or the gap adjusting ring 2 and the base 1) are integrally fixed by vacuum suction or the like. Further, in FIG. 1B, the illumination light is radiated toward the mirror M from the lower side (base 1 side) of the figure, but the reflection surface of the mirror M is reversed (see FIG. 1B). The illumination light may be emitted from the upper side of FIG. 1B toward the upper side). At this time, each of the space adjusting ring 2 and the holding member 3 may have a cylindrical shape without an opening, instead of a cylindrical shape.

Further, when adjusting the position of the holding member 3 in the Z direction, the actuator 6 moves the gap adjusting ring 2 to the position shown in FIG.
In the Y direction (the inclination angle between the inclined surface 2A and the bottom surface 2B is 1
However, the moving direction is not limited to this. However, since the holding member 3 does not move in the Z direction even if the space adjusting ring 2 is moved in the X direction, it is necessary to move it in the other direction. In addition, the amount of movement of the gap adjusting ring 2 and the Z of the mirror M depending on the moving direction of the gap adjusting ring 2.
The relationship with the amount of movement in the direction changes. Therefore, if the relationship is obtained in advance, the mirror M can be adjusted to a desired position.

[0026]

As described above, according to the present invention, by appropriately selecting a state in which the adjusting member and the holding member are integrally fixed by the fixing means and a state in which the adjusting member and the holding member are relatively movable, the first The position of the optical element can be adjusted in the Z-axis direction by the driving means, and the position of the optical element can be adjusted in the XY directions by the second driving means. Therefore, the triaxial position adjustment of the optical element can be easily performed in a short time without replacing the washer. The second driving member has a function of driving the holding member in a predetermined direction within the reference plane and a function of limiting the movement of the holding member in the reference plane direction when the holding member is moved in a direction perpendicular to the reference plane. Because it doubles as
The device can be constructed relatively easily. Furthermore, when the optical element is moved in the XY directions, it does not move in the Z direction, and conversely, when it moves in the Z direction, it does not move in the XY directions.

[Brief description of drawings]

1A and 1B are views showing a schematic configuration of an adjusting device according to an embodiment of the present invention, FIG. 1A is a top view, and FIG. 1B is a side view of the device seen from a side.

FIG. 2 is a partial cross-sectional view showing a schematic configuration of a portion where an actuator 7 and a holding member 3 are in contact with each other.

[Explanation of symbols]

 M ... Mirror 1 ... Base 2 ... Interval adjustment ring 3 ... Holding member 4a-4d, 5a-5d ... Bolt 6, 7, 8 ... Actuator 21, 22 ... Stopper Tools 23a, 23b, 23c ... springs

Claims (1)

[Claims] 1. An optical element that constitutes an optical system is finely moved,
In a device for adjusting the position of the optical element with respect to the optical axis of the optical system, a movable member that moves two-dimensionally within a predetermined reference plane and has a mounting surface inclined with respect to the reference plane, and the movable member. A holding member that is disposed above and that holds the optical element and is movable along the mounting surface, and is provided on at least one of the movable member and the holding member, and includes the movable member and the holding member. A fixing member that switches between a first state in which the optical element is fixed integrally and a second state in which the optical element is relatively movable; and a moving member in the second state in order to move the optical element in a direction substantially perpendicular to the reference plane. First driving means for driving the movable member in a predetermined direction; driving the holding member in a predetermined direction within the reference plane in the first state; and the first driving means for moving the movable member in a predetermined direction. Drive in the direction In this case, the optical element is provided with a second drive means for restricting movement of the holding member in the reference plane direction so that the holding member moves only in a direction perpendicular to the reference plane. Position adjustment device.