JPH10229042A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection aligner allowing a a change of relative positions of a reticle and a projecting optical system relating to the projection aligner for projecting a pattern of the reticle on an exposure substrate through the projecting optical system. SOLUTION: Reflection mirrors 3 are fixed in the X, Y directions of the side of a reticle stage 2 of the projecting optical system 6. In the X, Y directions oriented to the reticle stage 2 of a second stand 5 supporting the reticle stage 2, a laser length-measuring unit 4 is mounted corresponding to a reflection mirror 3 mounted on the system 6. A fixed mirror of the laser length-measuring unit 4 is fixed on the second stand 5, and a relative positional difference between a fixed mirror of the second stand 5 and the reflection mirror 3 of the system 6 is made to be received by a light-receiving system as coherent light. Positional information of the system 6 and the second stand 5 measured by the laser length-measuring unit 4 is inputted to a control part 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection exposure apparatus for projecting a reticle pattern onto an exposure substrate via a projection optical system.

[0002]

2. Description of the Related Art A schematic structure of a conventional projection exposure apparatus will be described with reference to FIG. In FIG. 4, a reticle 1 on which a circuit pattern is drawn is placed on a reticle stage 2. The reticle stage 2 is mounted on a second gantry 5 and can move in a two-dimensional plane.

The entire projection exposure apparatus is installed on an installation surface via four anti-vibration pads 11 below the anti-vibration table 10.
The second mount 5 on which the reticle stage 2 is mounted is mounted on a first mount 7 supporting a projection optical system 6. The first mount 7 supporting the projection optical system 6 is a vibration isolator 10
Fixed on top. Also, on the anti-vibration table 10, the first
Below the projection area of the projection optical system 6 supported by the gantry 7, a substrate stage 9 on which an exposure substrate 8 such as a glass substrate or a semiconductor substrate is placed and which can move two-dimensionally is placed.

In this projection exposure apparatus, the substrate stage 9 is moved and positioned by a predetermined amount so that a predetermined exposure area of the exposure substrate 8 coincides with the image forming plane of the projection optical system 6.
When the exposure is completed, an operation of moving the next exposure area to the image forming plane of the projection optical system 6 is sequentially repeated to perform exposure on all the exposure areas on the exposure substrate, that is, a so-called step-and-repeat exposure operation. Is performed.

[0005]

In this step-and-repeat projection exposure apparatus, in order to improve the substrate processing capacity (so-called throughput) per apparatus, the exposure substrate 8 is placed and moved. Substrate stage 9
It is conceivable to make the stepping operation at high speed. To speed up the stepping operation of the substrate stage 9, it is necessary to accelerate and decelerate the substrate stage 9 in a short time. However, when the acceleration / deceleration of the substrate stage 9 is increased, the reaction force applied in the direction opposite to the moving direction of the substrate stage 9 increases, and the transmission of the reaction force becomes steep (that is, a step function). As a result, the vibration frequency component generated from the noise spreads to a high frequency range. This reaction force is transmitted to the anti-vibration pedestal 10 and gives vibration to the structure on the anti-vibration pedestal 10. As described above, on the anti-vibration table 10,
In addition to the substrate stage 9, a first gantry 7 supporting the projection optical system 6 is mounted, and a second gantry 5 supporting the reticle stage 2 is mounted on the first gantry 7. Therefore, when the reaction force due to the steep movement of the substrate stage 9 is transmitted to the vibration isolator 10, the first frame 7
And the second base 5 also vibrates. Since the mass and shape of the system of the first gantry 7 and the system of the second gantry 5 are different from each other, the first gantry 7 and the second gantry 5 are separated when the reaction force by the substrate stage 9 becomes steep and large. Start vibration at vibration amplitude and frequency.

The first mount 7 supports the projection optical system 6, and the second mount 5 supports the reticle stage 2 on which the reticle 1 is mounted. Accordingly, the projection optical system 6 and the reticle 1 vibrate at different amplitudes and frequencies with the vibrations of the gantry. While these are vibrating, the center of the reticle 1 and the optical axis of the projection optical system 6 are displaced. However, if exposure is started in a state where the deviation exceeds a predetermined allowable range, the exposure substrate A pattern shift occurs, and the manufacturing yield decreases. After all,
Since exposure must be started after a certain period of time until the substrate stage 9 completes the stepping operation and the vibration is attenuated, the throughput cannot be improved much.

Further, the rigidity of the first and second frames is increased to suppress the vibration frequency component so that the reticle 1 and the projection optical system 6 vibrate at substantially the same vibration amplitude and frequency, and Although it is conceivable to reduce the relative displacement between the projection optical system 1 and the projection optical system 6, there is a problem in that the weight of the entire apparatus increases and the cost increases. In order to improve the throughput based on the current apparatus configuration without modifying the rigidity of the members constituting the projection exposure apparatus, it is premised that the reticle 1 and the projection optical system 6 by the reaction force from the substrate stage 9 are used. Needs to be measured in almost real time.

An object of the present invention is to provide a projection exposure apparatus capable of detecting a change in a relative position between a reticle and a projection optical system.

[0009]

The object of the present invention will be described with reference to FIG. 1, which shows an embodiment of the present invention. An object of the present invention is to provide a reticle stage (2) on which a reticle (1) on which a pattern is formed is mounted and moved. A projection optical system (6) for projecting the image on the exposure substrate (8) and a substrate stage (9) on which the exposure substrate (8) is mounted and moved.
A projection exposure apparatus comprising measuring means (3, 4) for measuring a difference in relative position between a reticle (1) and a projection optical system (6) due to movement of a substrate stage (9). Achieved by

In the above-mentioned projection exposure apparatus, the measuring means (3, 4) includes a reflecting mirror (3) fixed to a side of the projection optical system (6) near the reticle stage (2), and a reticle stage ( And a reflecting mirror (4) fixed to a mount (5) that supports the two mirrors. The reflected light of the laser light applied to the two reflecting mirrors (3, 4) interferes with each other to reduce the relative position difference. It is characterized by measuring.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection exposure apparatus according to a first embodiment of the present invention will be described with reference to FIGS. First,
The configuration of the projection exposure apparatus according to the present embodiment will be described with reference to FIG. The projection exposure apparatus according to the present embodiment is characterized in that a measurement unit for measuring a relative position difference between a reticle and a projection optical system is provided. Other components are the same as those of the conventional projection exposure apparatus shown in FIG.
The same components are denoted by the same reference numerals. In FIG. 1, a reticle 1 on which a circuit pattern is drawn is illuminated by illumination light from an illumination unit (not shown). The reticle 1 is mounted on a reticle stage 2, and can move in a two-dimensional plane as the reticle stage 2 moves. The position of the reticle stage 2 in the X and Y directions is measured by a laser length measuring device (not shown), and the position is controlled by the control unit 15. The reticle stage 2 is mounted on a second gantry 5. The illumination light illuminating the circuit pattern of the reticle 1 is incident on the projection optical system 6 mounted on the first gantry, and forms an image of the circuit pattern on the projection plane of the projection optical system 6.

The entire projection exposure apparatus is installed on an installation surface via four anti-vibration pads 11 below the anti-vibration table 10.
Due to the anti-vibration pad 11 and the anti-vibration base 10, external vibration transmitted through the ground plane is suppressed to some extent. The second mount 5 on which the reticle stage 2 is mounted is mounted on a first mount 7 supporting a projection optical system 6.
The first gantry 7 supporting the projection optical system 6 is fixed on an anti-vibration table 10. Also, on the anti-vibration table 10, the first mount 7
Below the projection area of the projection optical system 6 supported by the camera, a substrate stage 9 on which an exposure substrate 8 such as a glass substrate or a semiconductor substrate is placed and which can move two-dimensionally is placed. The position of the substrate stage 9 in the X and Y directions is also measured by a laser length measuring device (not shown), and the position is controlled by the control unit 15.

The reticle stage 2 of the projection optical system 6
The reflecting mirrors 3 are fixed in the X and Y directions on the side portions closer to each other. In FIG. 1, the illustration of the reflecting mirror 3 in the Y-axis direction is omitted. In the X and Y directions of the second gantry 5 supporting the reticle stage 2 near the reticle stage 2, a laser measuring unit 4 corresponding to the reflecting mirror 3 attached to the projection optical system 6.
Is attached. The laser length measurement unit 4 includes a fixed mirror, a laser transmitter, a light receiving system that receives interference light, and the like. The illustration of the laser length measuring unit 4 in the Y-axis direction is omitted in FIG. The fixed mirror not shown is the second
It is attached to the gantry 5, and the difference in the relative position between the fixed mirror of the second gantry 5 and the reflecting mirror 3 of the projection optical system 6 is received by the light receiving system as interference light. Position information of the projection optical system 6 and the second gantry 5 measured by the laser measuring unit 4 is input to the control unit 15. The control unit 15 calculates the difference between the projection optical system 6 and the second gantry 5 from the reference position based on the position information from the laser measuring unit 4.
The control unit 15 inputs the difference from the reference position as an error signal to the control system of the reticle stage 2 to move the reticle stage 2 and correct the displacement between the projection optical system 6 and the reticle 1. I have.

FIG. 2 shows a state immediately after the substrate stage 9 starts a stepping operation in the + X direction. Second
The gantry 5 and the projection optical system 6 start vibrating upon receiving a reaction force in the −X direction. At this time, the positional deviation of the second gantry 5 and the projection optical system 6 from the reference position is sequentially measured by the reflecting mirror 3 and the laser length measuring unit 4 and fed back to the control system 15 so that the control system 15 becomes reticle stage 2 Is controlled so that the deviation between the center of the reticle 1 and the optical axis of the projection optical system 6 is reduced.

As described above, according to the projection exposure apparatus of the present embodiment, the relative position shift due to the vibration between the reticle 1 and the projection optical system 6 is measured and fed back to the movement control system of the reticle stage 2 to provide the reticle stage. 2 is moved, the displacement between the center of the reticle 1 and the optical axis of the projection optical system 6 can be reduced, and the stepping operation of the substrate stage 9 can be performed at a high speed to improve the throughput. .

Next, a projection exposure apparatus according to a second embodiment of the present invention will be described with reference to FIG. The projection exposure apparatus according to the present embodiment is also characterized in that a measurement unit for measuring a relative position difference between the reticle and the projection optical system is provided. The other components are the same as those of the projection exposure apparatus according to the first embodiment shown in FIG. 1, and therefore, the same components are denoted by the same reference numerals and description thereof will be omitted. In FIG. 3, a light receiving unit 13 including an image pickup device such as a CCD is fixed above the projection optical system 6. In addition, a laser light transmission system 12 that emits a laser beam having a predetermined spot diameter that passes through the reticle 1 and enters the light receiving unit 13 is provided above the second gantry 5. The spot position of the laser beam incident on the light receiving unit 13 is imaged by the imaging device and
5 is input.

When the substrate stage 9 starts a stepping operation in the + X direction as shown in FIG. 2 in a state where the laser beam emitted from the laser transmitting system 12 is incident on the image pickup device of the light receiving section 13, the second The gantry 5 and the projection optical system 6 start vibrating upon receiving a reaction force in the −X direction. The second stand 5 at this time
From the upper laser transmission system 12 to the light receiving unit 13 on the projection optical system 6
The position of the spot of the laser light incident on the laser beam is shifted from the reference position by an amount corresponding to the shift between the second gantry 5 and the projection optical system 6. By feeding back the positional deviation to the control system 15 sequentially, the control system 15 controls the movement of the reticle stage 2 so as to reduce the deviation between the center of the reticle 1 and the optical axis of the projection optical system 6. Can be.

As described above, also in the projection exposure apparatus according to the present embodiment, the relative position shift due to the vibration between the reticle 1 and the projection optical system 6 is measured and fed back to the movement control system of the reticle stage 2 to thereby control the reticle stage 2. Is moved, the displacement between the center of the reticle 1 and the optical axis of the projection optical system 6 can be reduced, and the stepping operation of the substrate stage 9 can be performed at a high speed to improve the throughput.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above embodiment, the difference between the projection optical system 6 measured by the laser measuring unit 4 and the reference position of the second gantry is fed back to the position control system of the reticle stage 2 to move the reticle stage 2. Thus, the deviation between the center of the reticle 1 and the optical axis of the projection optical system 6 is corrected. However, the feedback control is not performed, and the position from the reference position measured by the laser length measurement unit 4 or the light receiving unit 13 is adjusted. The difference may be compared with a predetermined allowable value, and exposure may be started when the difference falls within the allowable range.

[0020]

As described above, according to the present invention, a change in the relative position between the reticle and the projection optical system can be detected.
The position of the reticle and the position of the projection optical system can be corrected based on the change in the position.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an operation of the projection exposure apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a schematic configuration of a projection exposure apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a conventional projection exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reticle 2 Reticle stage 3 Reflector 4 Laser measuring unit 5 2nd pedestal 6 Projection optical system 7 1st pedestal 8 Glass substrate 9 Substrate stage 10 Support stand 11 Support leg 12 Laser transmission system 13 Light receiving unit 15 Control unit

Claims (2)

[Claims] A reticle stage for mounting and moving a reticle on which a pattern is formed; a projection optical system for projecting an image of the pattern onto an exposure substrate; and a substrate stage for mounting and moving the exposure substrate. A projection exposure apparatus, comprising: a measurement unit configured to measure a difference in a relative position between the reticle and the projection optical system due to the movement of the substrate stage. 2. The projection exposure apparatus according to claim 1, wherein said measuring means is fixed to a reflecting mirror fixed to a side of said projection optical system near said reticle stage, and to a gantry supporting said reticle stage. And a reflection mirror for measuring the relative position difference by causing reflected light of the laser light applied to the two reflection mirrors to interfere with each other.