JPH11329965A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any position deviation error between a reticule and a wafer from being generated even when a stage system for supporting a reticule, projecting optical system, and wafer is inclined. SOLUTION: When a projection magnification from a reticule 16A of a projecting optical system PL on a wafer 8 is 1/M (M is a positive real number), an interval M/L in a direction in parallel to the optical axis of the projecting optical system PL of light beams made incident to a reticule side moving mirror 24 and a reticule side fixed mirror 25 is set as M times as large as an interval L in a direction in parallel to the optical axis of the projecting optical system PL of the light beams made incident to a moving mirror 9 for an X axis and a fixed mirror 10 for an X axis at the wafer 8 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus provided with a mechanism for measuring the positions of a reticle and a wafer by, for example, a laser interferometer method.

[0002]

2. Description of the Related Art When a semiconductor element, a liquid crystal display element, a thin film magnetic head, or the like is manufactured by a photolithography process, a pattern of a photomask or a reticle (hereinafter, collectively referred to as a "reticle") is exposed through a projection optical system. A projection exposure apparatus that performs projection exposure on a substrate is used. In such a projection exposure apparatus, since it is necessary to accurately position the photosensitive substrate, a laser interferometer is used as a length measuring system of the stage on the photosensitive substrate side.

FIG. 5 shows a projection exposure apparatus provided with a conventional laser interferometer. In FIG. 5, a stage support 3 is mounted on a base 1 via vibration-proof springs 2A and 2B, and a stage support is provided. On the base 3, a column 4 made of invar (an alloy having a low expansion coefficient) is implanted. Anti-vibration spring 2A
2B prevents various vibrations from the floor on which the base 1 is placed from being transmitted to the stage support 3 side. A lens barrel 5 is held in the middle stage of the column 4, and a projection optical system PL having a projection magnification of ５ is housed inside the lens barrel 5. A wafer-side Y stage 6 is placed in an area surrounded by the column 4 on the stage support 3, a wafer-side X stage 7 is placed on the wafer-side Y stage 6, and a wafer-side X stage 7 is placed on the wafer-side X stage 7. Holds a wafer 8 as a photosensitive substrate.

The wafer-side Y stage 6 includes a projection optical system PL.
The wafer 8 is positioned in a Y direction perpendicular to the plane of FIG.
Performs positioning of the wafer 8 in the X direction perpendicular to the Y axis in a plane perpendicular to the optical axis AX1 of the projection optical system PL. Although not shown, a Z stage for positioning the wafer 8 in the Z direction parallel to the optical axis AX1 of the projection optical system PL is also mounted on the wafer-side X stage 7.

In the laser interferometer on the wafer 8 side, an X-axis movable mirror 9 is attached to one end of the wafer-side X stage 7 in the X direction.
Is fixed, and an X-axis fixed mirror (reference mirror) 10 is attached to one end of the lens barrel 5 in the X direction. Further, a beam splitter 12 is fixed to an end of the base 1 in the X direction via a support 14, and a reflection prism 11 is provided above the beam splitter 12 at a portion where the support 14 is extended (not shown).
Has been fixed. The laser beam emitted from the X-axis laser interferometer main body 13 fixed to a support (not shown) is split by the beam splitter 12 into a wafer-side measurement beam WS and a wafer-side reference beam WR. The wafer-side measurement beam WS is reflected by the X-axis movable mirror 9 and returns to the beam splitter 12 again. The wafer-side reference beam WR is reflected by the reflection prism 11 and travels to the X-axis fixed mirror 10. After being reflected, the light returns to the beam splitter 12 through the reflecting prism 11 again. The wafer-side measurement beam WS between the beam splitter 12 and the X-axis movable mirror 9 and the wafer-side reference beam WR between the reflection prism 11 and the X-axis fixed mirror 10 are parallel to each other and X Parallel to the axis.

The two beams WS and WR returned to the beam splitter 12 are incident on a receiver (light receiving unit) attached to the X-axis laser interferometer main body 13. In practice, both beams WS and WR returned to the beam splitter 12
May be emitted in a direction orthogonal to the direction of incidence from the X-axis laser interferometer main body 13. In this case, the receiver is disposed on the bottom side of the beam splitter 12. For example, in the case of the heterodyne method, the frequency of the wafer-side reference beam WR and the wafer-side length measurement beam WS at the time of emission from the beam splitter 12 are very small Δf.
Only the X-axis movable mirror 9
A beat signal whose frequency changes from Δf in accordance with the moving speed in the direction is output. By processing this beat signal, the amount of change in the optical path length of the wafer-side measured beam WS with reference to the optical path length of the wafer-side reference beam WR, and hence the X-axis when the X-axis fixed mirror 10 is referenced, The coordinates of the movable mirror 9 in the X direction are measured with high resolution and high accuracy.

In the case of the homodyne method, the wafer-side reference beam WR and the wafer-side length measurement beam WS have the same frequency, and the receiver is, for example, the X of the movable mirror 9.
It is composed of two light receiving elements that output two-phase signals having a 90 ° phase difference whose phase changes sinusoidally according to the position in the direction. By supplying the two-phase signals to, for example, an up / down counter having an electronic interpolation function, the coordinates of the X-axis movable mirror 9 in the X direction are measured. Although only the X-axis laser interferometer is shown in FIG. 5, a Y-axis laser interferometer for detecting the Y-direction coordinates of the wafer-side Y stage 6 is also provided.

In FIG. 5, a reticle stage 15 is fixed to an upper end of a column 4, a reticle 16 is held on the reticle stage 15, and a pattern area of the reticle 16 is illuminated by exposure light IL from an illumination optical system 17. I have. The pattern of the reticle 16 is changed to 1 by the projection optical system PL.
The projected image reduced to / 5 is exposed on a certain shot area of the wafer 8. Thereafter, the wafer-side Y stage 6 and the wafer-side X stage 7 are driven to move the next shot area on the wafer 8 to the exposure field of the projection optical system PL to expose a reduced image of the pattern on the reticle 16. By repeating, a reduced image of the pattern of the reticle 16 is exposed on each shot area on the wafer 8.

[0009]

In the prior art as described above, the wafer-side Y stage 6 and the wafer-side X stage 7 on the stage support 3 are driven to move in a horizontal plane (XY).
The reticle 1 is positioned over the entire surface of the wafer 8 by positioning the wafer 8 in a step-and-repeat manner within a plane.
A reduced image of the pattern on 6 is exposed. When the stages 6 and 7 move in this manner, the center of gravity of the apparatus on the stage support 3 changes, or the projection optical system PL is moved with respect to the support 14 supporting the beam splitter 12 due to the recoil of stage drive or the like. The column 4 that supports the lens barrel 5 may be inclined.

FIG. 6 shows a state in which the projection exposure section including the lens barrel 5 and the wafer 8 is tilted with respect to the support table 14, and the optical axis AX1 of the projection optical system in the lens barrel 5 is set to the original Z axis. It is inclined by an angle θ with respect to the parallel optical axis AX0. In this case, X
A reference beam WR on the wafer side toward the fixed mirror 10 for the shaft;
Assuming that the distance in the Z direction from the wafer-side measurement beam WS toward the axis movable mirror 9 is L, the beam splitter 12
The optical path length up to the fixed axis mirror 10 and the beam splitter 1
The optical path difference from the optical path length from 2 to the X-axis movable mirror 9 is L ·
An error of sin θ (≒ L · θ) occurs. The reticle 16, the projection optical system PL, and the wafer 8 necessary for the projection exposure are all supported by the stage support 3 or the column 4 implanted in the stage support 3. Therefore, even if the stage support 3 rotates, they are rotated. The relative imaging relationship does not change, and does not result in a displacement error at the time of exposure.

However, as shown in FIG. 6, when an error occurs in the optical path difference between the optical path length to the X-axis fixed mirror 10 and the optical path length to the X-axis movable mirror 9, the wafer 8 moves in the X direction. Since the exposure is performed while moving by the error, a displacement error occurs between the wafer 8 and the conjugate image of the reticle 16A.
For example, assuming that a circuit pattern of the first layer is formed on the wafer 8 and such a positional error occurs when exposing a circuit pattern of the second layer on the wafer 8, There is a disadvantage that the overlay error between the first layer and the second layer becomes worse.

In view of the foregoing, it is an object of the present invention to provide a projection exposure apparatus which does not generate a displacement error between a reticle and a wafer even when a reticle, a projection optical system, and a stage system supporting a wafer are inclined. And

[0013]

According to the projection exposure apparatus of the present invention, as shown in FIG. 1, for example, a projection optical system (P) for projecting a pattern image of a mask (16A) onto a photosensitive substrate (8).
L) and the projection optical system (P) holding the mask (16A).
L) a mask stage (23) for moving the mask (16A) in a plane perpendicular to the optical axis, and holding the photosensitive substrate (8) and exposing in a plane perpendicular to the optical axis of the projection optical system (PL). A substrate stage (6, 7) for moving the substrate (8), a mask-side interferometer (24, 25, 26) for detecting a moving amount of the mask stage (23) in a predetermined direction, and a substrate stage (6, 7). ) In a projection exposure apparatus having a substrate-side interferometer (9, 10, 13) for detecting an amount of movement in a direction conjugate to the predetermined direction, the mask-side interferometer is mounted on a mask stage (23). Mask-side moving mirror (24)
A mask-side reference mirror (25) fixedly attached to a mask-side guide section (22) on which a mask stage (23) is mounted, a mask-side movable mirror (24) and a mask-side reference mirror A mask-side interference measuring means (26) for irradiating a light beam in parallel to (25) and causing the light beams reflected from the mask-side moving mirror and the mask-side reference mirror to interfere with each other.

Further, according to the present invention, a substrate-side moving mirror (9) mounted on a substrate stage (6, 7) and a substrate-side interferometer mounted on the substrate stage (6, 7) are provided. A light beam is irradiated in parallel to the substrate-side reference mirror (10), which is fixed so as not to move with respect to the guide portion (3), and the substrate-side movable mirror (9) and the substrate-side reference mirror (10). A substrate-side interference measuring means for interfering light beams reflected from the substrate-side moving mirror and the substrate-side reference mirror, respectively (13)
And a mask (16A) for the projection optical system (PL).
The projection optics of the light beams incident on the mask-side moving mirror (24) and the mask-side reference mirror (25), respectively, when the projection magnification from the substrate to the photosensitive substrate (8) is 1 / M (M is a positive real number). The distance L1 in the direction parallel to the optical axis of the system (PL) is set to be parallel to the optical axis of the projection optical system (PL) of the light beam incident on the substrate-side moving mirror (9) and the substrate-side reference mirror (10). This is set to M times the interval L2 in the direction.

In this case, it is desirable to mount the mask-side reference mirror (25) and the substrate-side reference mirror (10) so as to face the side surfaces of the lens barrel (5) of the projection optical system (PL).

[0016]

According to the present invention, for example, as shown in FIG. 3A, the optical axis AX1 of the projection exposure section including the mask (16A), the projection optical system (PL) and the photosensitive substrate (8) is originally Is tilted by an angle θ with respect to the optical axis AX0, the light beam (WS) incident on the substrate-side moving mirror (9) based on the optical path length of the light beam (WR) incident on the substrate-side reference mirror (10)
The optical path length of the mask-side reference mirror (2
The optical path length of the light beam (RS) incident on the mask-side moving mirror (24) with reference to the optical path length of the light beam (RR) incident on 5) changes by ΔX1. In this case, the light beam (R
R, RS) is equal to M of the light beam (WS, WR) interval.
Since it is twice, the following equation holds. ΔX1 = M · ΔX2

Next, as shown in FIG. 3B, the substrate stage (6, 6)
7) The side moves by -ΔX2, and the mask stage (2
3) The side moves by -ΔX1. Thus, the amount of change in the optical path length of the light beam (RS) on the mask side and the amount of change in the optical path length of the light beam (WS) on the substrate side become zero. In this case, for example, the mask (16) on the optical axis AX1 in FIG.
Assuming that the point (30) of A) and the point (30P) on the photosensitive substrate (8) are conjugate, in FIG.
P) moves to the right from the optical axis AX1 by −ΔX2, and the point (30) moves from the optical axis AX1 to −ΔX1 (= −M · ΔX2).
Just moving to the left. However, since the projection magnification of the projection optical system (PL) is 1 / M, the point (30) and the point (30P) are also conjugated in FIG.
Therefore, even if the optical axis AX1 is inclined by an arbitrary angle θ, the superposition accuracy of the conjugate image of the mask (16A) and the photosensitive substrate (8) is maintained at high accuracy.

Next, when the mask-side reference mirror (25) and the substrate-side reference mirror (10) are attached to face the side surfaces of the lens barrel (5) of the projection optical system (PL), respectively, the light beams (WR, WR, WS) and the intervals of the light beams (RS, RR), while simplifying the overall configuration.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a projection exposure apparatus according to the present invention will be described below with reference to FIGS. In the present embodiment, the present invention is applied to a so-called slit scan exposure type projection exposure apparatus. The conventional example of FIG.
Although this is a reduction projection type exposure apparatus (stepper) of the AND repeat type, in FIGS. 1 to 3, the portions corresponding to FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a projection exposure apparatus according to the present embodiment. In FIG. 1, a stage support 3 is mounted on a center portion of a base 18 via anti-vibration springs 2A and 2B. The projection magnification is 1 / M (M) through the lens barrel 5 to the middle stage of the implanted Invar (low expansion coefficient alloy) column 4.
Is mounted with the projection optical system PL of, for example, 5).
A wafer-side Y stage 6 and a wafer-side X stage 7 are placed at the center of the stage support 3, and a wafer 8 is held on the wafer-side X stage 7. The movable mirror 9 for the axis is attached, and the fixed mirror 10 for the X axis
Is attached. Wafer-side X stage 7 of this example
Also has a function of scanning the wafer 8 at a constant speed in the X direction when performing slit scan exposure.

Further, a beam splitter 12 and a reflecting prism 11 are fixed to a support 14 implanted at an end of the base 18 in the X direction, and a laser beam from an external X-axis laser interferometer main body 13 is used. Splitter 12
The beam is divided into a wafer-side reference beam WR and a wafer-side length measurement beam WS, and these beams WR and WS are incident on the X-axis fixed mirror 10 and the X-axis movable mirror 9, respectively.
The beams WR and WS are parallel to the X axis, and the interval between the beams WR and WS in the optical axis direction (Z direction) of the projection optical system PL is L. X-axis laser interferometer body 1
Numeral 3 constantly measures the X-direction coordinates of the X-axis movable mirror 9 with respect to the X-axis fixed mirror 10 from the amount of change in the optical path length of the wafer-side measurement beam WS with respect to the optical path length of the wafer-side reference beam WR. doing. The drive unit of the wafer-side X stage 7 sets the coordinates of the wafer-side X stage 7 in the X direction based on the measurement result of the X-axis laser interferometer main body 13.

A support 19 is planted at an end of the base 18 opposite to the support 14, a beam splitter 20 is fixed to an upper end of the support 19, and a reflection prism 21 is provided at a middle portion of the support 19. Fixed. A reticle stage support 22 is fixed to the upper end of the column 4, and a reticle scanning stage 23 is slidably mounted on the reticle stage support 22 in the X direction.
A reticle 16A on which a transfer pattern is formed is held. A reticle-side moving mirror 24 is fixed to an end of the reticle scanning stage 23 in the X direction, and a reticle-side fixed mirror 2 is mounted on a side of the lens barrel 5 of the projection optical system PL in the X direction.
5 is fixed.

In this case, the X-axis fixed mirror 10 on the wafer side and the reticle-side fixed mirror 25 are mounted so as to face the side surface of the lens barrel 5 in the X direction. Then, the laser beam emitted from the external reticle laser interferometer main body 26 (not shown) is split by the beam splitter 20 into a reticle-side measurement beam RS and a reticle-side reference beam RR. The reticle-side measuring beam RS is reflected by the reticle-side moving mirror 24 and returns to the beam splitter 20 again. The reticle-side reference beam RR is reflected by the reflecting prism 21 and travels to the reticle-side fixed mirror 25. After being reflected, the light returns to the beam splitter 20 via the reflecting prism 21 again.

The reticle-side measurement beam RS between the beam splitter 20 and the reticle-side movable mirror 24 and the reticle-side reference beam RR between the reflection prism 21 and the reticle-side fixed mirror 25 are parallel to each other, and Parallel to the X axis. The distance in the Z direction between the reticle-side measurement beam RS incident on the reticle-side movable mirror 24 and the reticle-side reference beam RR incident on the reticle-side fixed mirror 25 is ML. That is, for a projection magnification 1 / M of the projection optical system PL from the reticle 16A to the wafer 8, the distance in the Z direction between the reticle-side measurement beam RS and the reticle-side reference beam RR is equal to the wafer-side measurement beam WS. Wafer side reference beam WR
Is set to M times as large as the distance in the Z direction.

The two beams RS and RR returned to the beam splitter 20 are applied to the reticle laser interferometer main body 2.
The light enters a receiver (light receiving unit) attached to 6. actually,
Both beams RS and R returned to the beam splitter 20
In some cases, R is emitted in a direction orthogonal to the direction of incidence from the reticle laser interferometer main body 26, in which case the receiver is arranged on the upper side of the beam splitter 20. Then, similarly to the X-axis laser interferometer main body 13 on the wafer side, the reticle laser interferometer main body 2
6 is the difference between the optical path length of the reticle-side reference beam RR and the optical path length of the reticle-side measurement beam RS by the heterodyne method or the homodyne method, and furthermore, the X of the reticle-side movable mirror 24 with reference to the reticle-side fixed mirror 25. Direction coordinates are measured with high resolution and high accuracy. A fixed cylinder (cover) that covers at least the optical path of the laser beam toward the fixed mirror 25 among the optical paths of the laser beam emitted from the beam splitter 20 and directed to the movable mirror 24 and the fixed mirror 25 is provided. It is also possible to prevent the measurement accuracy of the interferometer from decreasing due to the above. At this time, a gas whose temperature is controlled may further flow inside the fixed cover. This is because the optical path of the laser beam toward the fixed mirror 25 can be long due to the configuration of the interferometer of the present embodiment.
Further, a cover for covering the optical path of the laser beam toward the movable mirror 24 may be provided. At this time, it is desirable that the cover be configured to be able to expand and contract in accordance with the movement of the stage 23. Further, the cover as described above may be provided for the interferometer on the wafer side.

A drive unit (not shown) of the reticle scanning stage 23 adjusts the coordinate position of the reticle scanning stage 23 in the X direction based on the measurement result of the reticle laser interferometer main body 26. In the present embodiment, the illumination optical system 27
Exposure light IL emitted from illuminates a slit-shaped illumination area 28 on reticle 16A. This illumination area 28
Is a rectangular area inscribed in the circular area 29 as shown in FIG. 2, and the illumination area 28 has an area only covering a part of the pattern area PA of the reticle 16A. In order to expose the entire pattern image of the pattern area PA of the reticle 16A onto the wafer 8, the scanning direction D orthogonal to the longitudinal direction of the illumination area 28 in FIG.
1 needs to scan the reticle 16A.

Returning to FIG. 1, the scanning direction D of the reticle 16A
1 is the -X direction. When scanning the reticle 16A in the −X direction at a constant speed V, the wafer side X
By driving the stage 7, the wafer 8 is scanned at a constant speed V / M in the X direction. Therefore, the X direction is the wafer 8
In the scanning direction D2. By scanning the reticle 16A and the wafer 8 in synchronization in this manner, the reticle 1
With the positional relationship between the conjugate image of 6A and the wafer 8 kept constant, a reduced image of 1 / M times the entire pattern of the reticle 16A is transferred to the exposure area of the wafer 8. At this time, in this embodiment, the stage support 3, the column 4, and the reticle stage support 22 are made of a material having high rigidity, and are not deformed by driving the reticle stage system and the wafer stage system during slit scan exposure. It has become.

Next, in this embodiment, the projection exposure section including the stage support 3 and the column 4 is tilted and the optical axis A of the projection optical system PL is tilted.
The operation when X1 is inclined will be described. FIG. 3 (a)
Is an optical axis AX where the optical axis AX1 of the projection optical system PL is parallel to the Z axis.
This shows a state in which the optical axis AX1 is inclined from 0 by an angle θ.
Are coincident with the optical axis AX0, the X-axis movable mirror 9 and the X-axis fixed mirror 10 are at the same position in the X direction, and the reticle-side movable mirror 24 and the reticle-side fixed mirror 25 are in the X direction. At the same position.

In the state shown in FIG. 3A, the X-axis fixed mirror 10
X with respect to the optical path length of the wafer-side reference beam WR incident on the
The optical path length of the wafer side measurement beam WS incident on the axis moving mirror 9 changes by ΔX2, and enters the reticle side moving mirror 24 with respect to the optical path length of the reticle side reference beam RR incident on the reticle side reference mirror 25. The optical path length of the reticle-side measurement beam RS changes by ΔX1. Since the interval between both beams WR and WS is M times the interval between both beams RS and RR,
The following equation holds. ΔX1 = M · ΔX2

Next, as shown in FIG. 3B, the wafer-side X stage 7 is moved by a predetermined amount in the scanning direction D2, that is, by -ΔX2 in the X direction, in order to cancel the change in the optical path length. The reticle scanning stage 23 moves by a predetermined amount in the scanning direction D1, that is, by -ΔX1 in the -X direction. Thus, the change amount of the optical path length difference on the reticle 16A side and the change amount of the optical path length difference on the wafer 8 side become zero. In this case, for example, the point 3 on the reticle 16A on the optical axis AX1 in FIG.
Assuming that 0 and the point 30P on the wafer 8 are conjugate, in FIG. 3B, the point 30P moves from the optical axis AX1 by -ΔX2 in the X direction, and the point 30 moves from the optical axis AX1 to the -X direction. Is moved by -ΔX1 (= −M · ΔX2). However, since the projection magnification of the projection optical system PL is 1 / M, the point 30 and the point 30P are conjugate also in FIG. Therefore, even if the optical axis AX1 is inclined by an arbitrary angle θ, the superposition accuracy of the conjugate image of the reticle 16A and the wafer 8 is maintained with high accuracy.

In the configuration shown in FIG. 1, the X-axis fixed mirror 10 and the reticle-side fixed mirror 25 are fixed to the lens barrel 5 of the projection optical system PL. Obviously, it may be fixed to 4b.
Next, various modifications of the present embodiment will be described with reference to FIG. In FIG. 4, parts corresponding to those in FIG. 1 are given the same reference numerals. First, in the modification of FIG. 4A, the X-axis fixed mirror 10 on the wafer side is fixed to the side surface of the stage support 3 below the X-axis movable mirror 9, and the reticle-side fixed mirror 25 is placed on the column 4. And fixed above the reticle-side movable mirror 24 on the side surface of the support base 31 further extended.

The X-axis movable mirror 9 and the X-axis fixed mirror 1
The direction of the 0 reflection surface is opposite to the direction of the reflection surfaces of the reticle-side moving mirror 24 and the reticle-side fixed mirror 25. Then, assuming that the projection magnification of the projection optical system PL is 1 / M, the wafer-side measurement beam WS incident on the X-axis movable mirror 9 and the X-axis fixed mirror 1
Assuming that the distance in the Z direction from the wafer-side reference beam WR incident on 0 is L, the reticle-side measurement beam RS incident on the reticle-side moving mirror 24 and the reticle-side reference beam RR incident on the reticle-side fixed mirror 25. The interval in the Z direction is set to ML. Even in this arrangement, similarly to the embodiment of FIG. 1, the reticle 16 when the optical axis AX1 of the projection optical system PL is tilted.
The superposition accuracy of the conjugate image of A and the wafer 8 is maintained with high accuracy.

Next, in the modification shown in FIG. 4B, the reticle-side moving mirror 24 is fixed on the reticle scanning stage 23 on the same side as the X-axis moving mirror 9 on the wafer side. Then, the X-axis fixed mirror 10 on the wafer side is fixed to the side surface of the lens barrel 5 above the X-axis movable mirror 9, and the reticle-side fixed mirror 25 is further extended on the column 4 to the side surface of the support base 31. And fixed above the reticle-side movable mirror 24. Therefore, the directions of the reflecting surfaces of the X-axis moving mirror 9 and the X-axis fixed mirror 10 are the same as the directions of the reflecting surfaces of the reticle-side moving mirror 24 and the reticle-side fixed mirror 25. Then, the projection magnification of the projection optical system PL is set to 1 / M, and the wafer-side length measurement beam W incident on the X-axis movable mirror 9 is set.
Wafer side reference beam W incident on S and X axis fixed mirror 10
Assuming that the distance in the Z direction from R is L, the reticle-side movable mirror 2
The distance in the Z direction between the reticle-side measurement beam RS incident on the reticle 4 and the reticle-side reference beam RR incident on the reticle-side fixed mirror 25 is set to ML. Even in this arrangement, as in the embodiment of FIG. 1, the superposition accuracy of the conjugate image of the reticle 16A and the wafer 8 when the optical axis AX1 of the projection optical system PL is inclined is maintained with high accuracy.

Next, in the modification shown in FIG. 4C, the reticle-side moving mirror 24 is fixed on the reticle scanning stage 23 on the same side as the X-axis moving mirror 9 on the wafer side. And
The X-axis fixed mirror 10 on the wafer side is fixed to the side surface of the stage support 3 below the X-axis movable mirror 9, and the reticle-side fixed mirror 25 is placed on the side of the lens barrel 5 below the reticle-side movable mirror 24. Fixed to. Therefore, the X-axis movable mirror 9 and the X-axis fixed mirror 1
The direction of the 0 reflection surface is the same as the direction of the reflection surfaces of the reticle-side moving mirror 24 and the reticle-side fixed mirror 25. And
Assuming that the projection magnification of the projection optical system PL is 1 / M, the distance in the Z direction between the wafer-side measurement beam WS incident on the X-axis movable mirror 9 and the wafer-side reference beam WR incident on the X-axis fixed mirror 10 is set. L, the distance in the Z direction between the reticle-side measurement beam RS incident on the reticle-side movable mirror 24 and the reticle-side reference beam RR incident on the reticle-side fixed mirror 25 is represented by M · L.
Set to. Also in this arrangement, similar to the embodiment of FIG. 1, reticle 1 when optical axis AX1 of projection optical system PL is inclined.
The superposition accuracy of the conjugate image of 6A and the wafer 8 is maintained with high accuracy.

In the above embodiment, the present invention is applied to a slit scanning type projection exposure apparatus.
In the step-and-repeat type projection exposure apparatus as well, when the position of the reticle 16 is detected by the laser interferometer method, the arrangement of the present invention is applied so that the conjugate image of the reticle 16 and the wafer 8 Is maintained with high accuracy. As described above, the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention.

[0036]

According to the present invention, the distance L1 between the light beams incident on the mask-side moving mirror and the mask-side reference mirror, respectively.
And the distance L2 between the light beams incident on the substrate-side moving mirror and the substrate-side reference mirror, respectively, are set in a predetermined relationship, so that errors due to the tilt of the stage system supporting the photosensitive substrate, the projection optical system, and the mask are offset. Therefore, there is an advantage that a displacement error between the mask and the photosensitive substrate does not occur.

In this case, the degree of freedom in the arrangement of the mask-side reference mirror and the substrate-side reference mirror is wide, and an optimum arrangement can be selected as needed. In the configuration in which the mask-side reference mirror and the substrate-side reference mirror are respectively mounted so as to face the side surfaces of the barrel of the projection optical system, the length of the device in the optical axis direction of the projection optical system is shortened, and the The configuration is also particularly simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a projection exposure apparatus according to the present invention.

FIG. 2 is a plan view showing a slit-shaped illumination area in FIG. 1;

3A is a side view showing a state in which the optical axis of the projection optical system PL in FIG. 1 is inclined, and FIG. 3B is a view showing a state where the change in the optical path length from the state in FIG. FIG. 9 is a side view showing a state where a side X stage 7 and a reticle scanning stage 23 are moved.

FIG. 4 is a configuration diagram of main parts showing various modifications of the embodiment of FIG. 1;

FIG. 5 is a configuration diagram showing a projection exposure apparatus provided with a conventional laser interferometer.

6 is an enlarged view showing a main part of the projection exposure apparatus of FIG. 5 in a state where a projection exposure unit is inclined.

[Explanation of symbols]

 2A, 2B Anti-vibration spring 3 Stage support 4 Column PL Projection optical system 5 Barrel of projection optical system 7 Wafer-side X stage 9 X-axis movable mirror 10 X-axis fixed mirror 13 X-axis laser interferometer main body 22 Reticle stage support 23 Reticle scanning stage 24 Reticle-side moving mirror 25 Reticle-side fixed mirror 26 Reticle laser interferometer main body 27 Illumination optical system

Claims (2)

[Claims] A projection optical system for projecting a mask pattern image onto a photosensitive substrate; a mask stage for holding the mask and moving the mask in a plane perpendicular to an optical axis of the projection optical system; A substrate stage that holds the photosensitive substrate and moves the photosensitive substrate in a plane perpendicular to the optical axis of the projection optical system, a mask-side interferometer that detects an amount of movement of the mask stage in a predetermined direction, and the substrate In a projection exposure apparatus having a substrate-side interferometer for detecting an amount of movement of a stage in a direction conjugate to the predetermined direction, the mask-side interferometer includes a mask-side moving mirror attached to the mask stage, and the mask A mask-side reference mirror mounted so as not to move with respect to the mask-side guide portion on which the stage is mounted, and a light beam is applied to the mask-side movable mirror and the mask-side reference mirror. A mask-side interferometer configured to irradiate a row and interfere with light beams respectively reflected from the mask-side moving mirror and the mask-side reference mirror, wherein the substrate-side interferometer is a substrate mounted on the substrate stage. A side-moving mirror, a substrate-side reference mirror attached so as not to move with respect to a substrate-side guide on which the substrate stage is mounted, and a light beam parallel to the substrate-side moving mirror and the substrate-side reference mirror. And substrate-side interference measurement means for irradiating light beams respectively reflected from the substrate-side moving mirror and the substrate-side reference mirror, and setting a projection magnification of the projection optical system from the mask to the photosensitive substrate. When 1 / M (M is a positive real number), the interval L in the direction parallel to the optical axis of the projection optical system between the light beams incident on the mask-side moving mirror and the mask-side reference mirror, respectively.
1. A projection exposure apparatus, wherein 1 is set to M times an interval L2 of light beams respectively incident on the substrate-side moving mirror and the substrate-side reference mirror in a direction parallel to the optical axis of the projection optical system. 2. The projection exposure apparatus according to claim 1, wherein the mask-side reference mirror and the substrate-side reference mirror are respectively mounted so as to face side surfaces of a barrel of the projection optical system.