JPH09239628A - Self-weight bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate the displacement to the behavior of the base of the on board article against the base with highly accurate following ability by feeding back the value obtained by multiplying the detected acceleration signal by conversion factor to a control means together with the deviated value. SOLUTION: This device has a servo system wherein the value detected by a Z axis detection means 105 is fed back to a linear motor controller 25, and a gate stage follows to the Z displacement of the XY movable stage corresponding to the Z displacement of a base. In addition, the value obtained by multiplying the acceleration signal of the XY movable stage in the Z direction, which is detected by an accelerometer 101, by a conversion factor 102 by means of a multiplier 103 is fed back to the linear motor controller 25. The following ability of the servo system in a limited servo gain can be improved by feeding back the acceleration of the base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-weight supporting device for supporting the self-weight of a mechanical structure including an XY stage of a semiconductor manufacturing apparatus, a precision machine tool, a precision measuring instrument and the like.

[0002]

2. Description of the Related Art FIG. 6 shows a tilt stage to which a conventional self-weight supporting device is added. In the figure, reference numeral 1 denotes a tilting stage, and an upper surface 2 of the tilting stage 1 is required to have extremely high surface accuracy for mounting a wafer 3. 20
0 is the base, 6 is the XY movable stage, and the base 20
It can move in the XY directions with respect to 0. The XY movable stage 6 is rigidly guided with respect to the base 200 by, for example, a combination of a hydrostatic bearing and a pressurizing magnet (not shown), and can be almost completely aligned with the displacement of the base in the Z direction. Reference numeral 4 denotes a guide that has a cylindrical guide surface and restricts the tilt stage 1 only in the horizontal direction. For example, by using a porous hydrostatic bearing, movement in the Z direction, the tilt direction, and the Z axis rotation direction can be performed. Tolerate. 5 (5
a, 5b) is a weight supporting device, and 105 (105a,
Reference numeral 105b) is a Z detecting means for detecting the relative displacement of the tilt stage 1 in the Z direction with respect to the XY movable stage 6 in the vicinity of the weight supporting device 1. For example, by using a capacitance sensor, the Z relative displacement is highly accurately measured. be able to. Based on the detection values obtained by the three Z detection means 105, the tilt stage 1 is driven by driving the three self-weight supporting devices 5 (the remaining one of each of the Z detecting means and the self-weight supporting device is not shown). The displacement or inclination of the XY movable stage 6 in the Z direction, which is the direction of gravity, can be automatically controlled at high speed. Further, with the above configuration, the tilt stage 1 can move in the XY directions together with the XY movable stage 6.

FIG. 2 is an enlarged view of the weight supporting device 5a shown in FIG. The self-weight supporting device includes a linear motor unit 300 and a self-weight supporting unit 400. The linear motor unit 300 includes a permanent magnet 8, a coil 9, a non-magnetic coil holder 10, a magnetic yoke 7, and a yoke holder 11. The coil holder 10 is provided with a cooling pipe 12 so as to cover the coil 9 in order to recover the heat generated from the coil 9, and the refrigerant can be made to flow from the outside. The direction of the magnetic field of the permanent magnet 8 and the direction of the current flowing through the coil 9 are such that the Lorentz force acts in the Z direction.

The self-weight supporting portion 400 comprises a cylinder 13, a piston 15 and a rolling seal 14. An air chamber 16 between the cylinder 13 and the piston 15 is completely sealed by a rolling seal 14. The piston 15 is fixed to the coil holder fitting 10. The cylinder 13 is fixed to the yoke holder 11. With such a configuration, the force generated by the linear motor unit 300 and the force generated by the cylinder 13 act coaxially in the Z direction, and drive the tilt stage 1 via the yoke holder 11. The rigidity due to the compressibility of the air in the air chamber 16 is very weak, and the natural frequency determined by the inertia of the tilt stage 1 is low.

Next, the drive system of the self-weight supporting device will be described. In FIG. 7, 19 is an air supply source. Reference numeral 17 is an air supply port, and 18 is an air discharge port. Reference numeral 20 is a servo valve for controlling the air pressure. Reference numeral 21 is a diaphragm, and the secondary side is open to the atmosphere. Reference numeral 24 is a pressure controller that gives a command to the servo valve 20. Reference numeral 22 is a pressure gauge for measuring the cylinder pressure. Pressure controller 24
Uses the signal 23 of the pressure gauge 22 as a feedback signal to realize a control system in which the cylinder pressure is constant. A linear motor controller 25 includes a current amplifier for driving the linear motor. The detection value Z of the Z detection means 105 is fed back to the linear motor controller, and X corresponding to the Z displacement of the tilt stage is the base.
It is a servo system that follows the Z displacement of the Y movable stage. In order to improve the followability, (1) the higher the Z servo gain is, the more desirable. (2) The higher the rigidity of the weight supporting portion, the more desirable. However, the servo gain is finite. Further, if the rigidity of the self-weight supporting portion is increased too much, the controllability may be impaired. Due to the above, the followability of the servo system is limited.

[0006]

In the above-mentioned conventional example, for example, when the XY stage is stepwise moved in the horizontal direction, the following problems occur. The reaction force of the driving force for stepping the XY stage is applied to the base. As a result, the base is largely displaced, and displacement is also generated in the Z direction as another component. As described above, the tracking capability of the servo system with respect to the displacement in the base Z direction is limited, and the amount (deviation) that cannot follow the magnitude or frequency of the base Z displacement may be unacceptable.

The present invention has been made in view of the problems in the above-mentioned conventional example, and an object thereof is to provide a self-weight supporting device capable of extremely high followability with respect to a base.

[0008]

In order to achieve the above object, the self-weight supporting device of the present invention supports the driving means for moving the driven body in the direction of gravity from the base (base) and the self-weight of the driven body. Self-weight including a support means, a detection means for detecting displacement of the driven body in the gravity direction with respect to the base in the vicinity of the drive means, and a control means for controlling the position of the driven body in the gravity direction based on the value detected by the detection means. In the supporting device, an acceleration signal in the gravity direction of the base is detected, and a value obtained by multiplying the acceleration signal by a conversion coefficient is fed back to the control means.

Further, a horizontal movable body having a driven body mounted thereon and held by the base so as to be movable in the horizontal direction with respect to the base, and the degree of freedom in the horizontal direction with respect to the horizontal movable body are restricted, and other freedom is provided. A bearing that holds the driven body so that the driven body can move with respect to each other, drive means that moves in the gravity direction from the horizontal movable body, and support means that supports the weight of the driven body.
And control for controlling the position or inclination of the driven body in the direction of gravity based on the value detected by the detection means, the detection means detecting a displacement of the driven body in the direction of gravity with respect to the horizontal movable body in the vicinity of the driving means. In the self-weight supporting device including means, acceleration signals in the gravity direction at a plurality of points on the horizontal movable body may be detected, and a value obtained by multiplying the conversion coefficient may be fed back to the control means.

Further, the driven body is mounted and the horizontally movable body is held by the base so as to be movable in the horizontal direction with respect to the base, and the degree of freedom in the horizontal direction of the horizontally movable body is restricted. Bearing for holding the driven body so as to be movable with respect to the degree of freedom, driving means for moving in the gravity direction from the horizontal movable body, the supporting means for supporting the weight of the driven body, and the vicinity of the driving means. A plurality of sets of detection means for detecting displacement of the driven body in the direction of gravity with respect to the horizontal movable body, and a self-weight including control means for controlling the position or inclination of the driven body in the direction of gravity based on the value detected by the detection means. In the supporting device, acceleration signals in the gravity direction at a plurality of points on the base are detected, a value obtained by multiplying the conversion coefficient is fed back to the control means, and the conversion coefficient is the horizontal movable body. It may be such a variable configuration depending on the horizontal position on the over scan.

[0011]

With the above structure, it is possible to achieve extremely high followability with respect to large Z-direction movement fluctuations of the base when the XY stage is stepwise moved horizontally, for example. Moreover, an appropriate effect can be obtained regardless of the position of the horizontally movable body on the base in the horizontal direction.

[0012]

【Example】

(First Embodiment) FIG. 1 shows a tilt stage to which a weight supporting device of the present invention is added. Reference numeral 1 denotes a tilting stage, and an upper surface 2 of the tilting stage 1 is required to have extremely high surface accuracy for mounting the wafer 3. Reference numeral 200 denotes a base, 6 denotes an XY movable stage, and the XY movable stage 6
Can move in the XY directions with respect to the base 200.
The XY movable stage 6 is rigidly guided with respect to the base 200 by, for example, a combination of a hydrostatic bearing and a pressurizing magnet (not shown), and can almost completely follow the displacement of the base in the Z direction. 4 is a guide that has a cylindrical guide surface and that restricts the tilt stage 1 only in the horizontal direction,
For example, by using a porous hydrostatic bearing,
The movement in the tilt direction and the Z-axis rotation direction is allowed.
Reference numeral 5 (5a, 5b) is a weight supporting device. 105 (10
5a and 105b) are Z detecting means for detecting the relative displacement of the tilt stage 1 in the Z direction with respect to the XY movable stage 6 in the vicinity of the weight supporting device 5. For example, by using a capacitance sensor, the relative displacement in the Z direction can be detected with high accuracy. It can be measured. Based on the detection values obtained by the three Z detection means 105, the tilt stage 1 is driven by driving the three self-weight supporting devices 5 (the remaining one of each of the Z detection means and the self-weight supporting device is not shown). The Z direction, which is the direction of gravity, or the tilt of the XY movable stage 6 can be automatically controlled at high speed. Further, with the above configuration, the tilt stage 1 can move in the XY directions together with the XY movable stage 6.

Further, 100 (100a, 100b) is an accelerometer, and a total of three accelerometers are fixed near the three weight supporting devices 5 of the XY movable stage 6, respectively. Direction) is being detected. As described above, since the Z-direction displacement of the XY movable stage 6 matches the Z-direction displacement of the base 200, it is equivalent to detecting the acceleration of the base.

FIG. 2 is an enlarged view of the weight supporting device 5 in FIG. The self-weight supporting device 5 includes a linear motor unit 300 and a self-weight supporting unit 400. The linear motor unit 300 includes a permanent magnet 8, a coil 9, a non-magnetic coil holder 10, a magnetic yoke 7, and a yoke holder 11. The coil holder 10 is provided with a cooling pipe 12 so as to cover the coil 9 in order to recover the heat generated from the coil 9, and the refrigerant can be made to flow from the outside. The direction of the magnetic field of the permanent magnet 8 and the direction of the current flowing through the coil 9 are such that the Lorentz force acts in the Z direction.

The self-weight supporting portion 400 comprises a cylinder 13, a piston 15 and a rolling seal 14. An air chamber 16 between the cylinder 13 and the piston 15 is completely sealed by a rolling seal 14. The piston 15 is the coil holder fitting 10 of the linear motor unit 300.
It is fixed to. The cylinder 13 is a linear motor unit 30.
It is fixed to the yoke holder 11 of 0. With such a configuration, the force generated by the linear motor unit 300 and the force generated by the cylinder 13 act coaxially in the Z direction, and drive the tilt stage 1 via the yoke holder 11.
The rigidity due to the compressibility of the air in the air chamber is very weak, and the natural frequency determined by the combination of the tilt stage 1 with the inertia is low.

Next, the drive system of the self-weight supporting device will be described. In FIG. 3, 19 is an air supply source. Reference numeral 17 is an air supply port, and 18 is an air discharge port. Reference numeral 20 is a servo valve for controlling the air pressure. Reference numeral 21 is a diaphragm, and the secondary side is open to the atmosphere. Reference numeral 24 is a pressure controller that gives a command to the servo valve. Reference numeral 22 is a pressure gauge for measuring the cylinder pressure. The pressure controller 24 uses the signal 23 of the pressure gauge 22 as a feedback signal to realize a control system in which the pressure in the cylinder is constant. A linear motor controller 25 includes a current amplifier for driving the linear motor. Linear motor controller 25
The detection value Z of the Z detection means 105 is fed back to the servo system to make the tilt stage 1 follow the Z displacement of the XY movable stage 6 corresponding to the Z displacement of the base 200. To improve tracking, (1) Z
The higher the servo gain in the direction, the better. (2) The higher the rigidity of the self-weight supporting portion 400, the more desirable. However, the servo gain is finite, and the rigidity of the self-weight supporting portion is extremely low as described above, so the followability of the servo system is limited.

In FIG. 3, 101 is an acceleration signal, 102 is a conversion coefficient, and 103 is a multiplier. A value obtained by multiplying the Z direction acceleration signal of the XY movable stage detected by the accelerometer by the conversion coefficient is used by the linear motor controller 25.
Feedback. In the above configuration, the followability of the servo system with a finite servo gain is based on the base 2
It can be improved by feeding back the acceleration of 00.

The influence of the base behavior on the XY movable stage when the XY movable stage moves horizontally on the base 200 will be described with reference to FIG. The tilt stage 201 when the XY movable stage is near the center of the base
The C, XY movable stage is represented by 206C. In addition, the tilt stage when the XY movable stage is at the end of the base is 20
The 1L, XY movable stage is represented by 206L. XY
The step movement of the movable stage in the horizontal direction causes the base 200 to behave in the stationary state as shown in, for example, FIG. 4B. On the other hand, if the Z servo system is not provided, the tilt stages 201C and 201L are located at the position indicated by the broken line in FIG. 4B. It must be made to follow the base behavior by the Z servo system (solid line in the figure). However, although the base behavior due to the step in the horizontal direction is reproduced, the degree of influence on the Z displacement of the tilt stage differs depending on the horizontal position of the XY movable stage. For example, when the XY movable stage is in the vicinity of the center of the base, the tilt stage 201C has an influence of the inclination (θ), but has almost no influence on the gravitational translation direction.
On the other hand, when the XY movable stage is located at the end of the base, the tilt stage 201L has an influence on the gravity translation direction (ZL) in addition to the inclination (θ).

However, according to this embodiment, since the accelerometer is fixed to the XY movable stage which is a movable body, XY
It is not necessary to consider that the influence of the base behavior on the displacement of the tilting stage in the Z direction differs depending on the horizontal position of the movable stage. As a result, the conversion coefficient may be a constant.

(Second Embodiment) Although the accelerometer 100 is fixed to the XY movable stage 6 in the first embodiment, it may be fixed to the base 200 as shown in FIG. More accurate followability can be obtained by detecting the acceleration of the base. However, as described above, the influence degree of the tilt stage in the Z direction differs depending on the horizontal position of the XY movable stage, and it becomes necessary to consider the influence degree by fixing the accelerometer to the base. In this case, the conversion coefficient may be a function of the position of the XY movable stage. In a simple example, each of the three conversion coefficients may be a linear function related to the position of the XY movable stage. Thereby, the same effect as the first embodiment can be obtained.

[0021]

As described above, according to the present invention,
For example, in comparison with the conventional method, when the XY stage is stepwise moved in the horizontal direction against a large variation in the Z-direction behavior of the base,
Enables extremely high tracking performance. Moreover, an appropriate effect can be obtained regardless of the horizontal position of the horizontally movable body on the base.

[Brief description of drawings]

FIG. 1 is a view showing a tilt stage equipped with a weight supporting device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of the weight supporting device in FIGS. 1 and 6.

FIG. 3 is a diagram showing a drive system of a weight supporting device of the present invention.

FIG. 4 is a diagram showing operational characteristics of the self-weight supporting device of the present invention when the tilt stage is driven in the Z direction.

FIG. 5 is a diagram showing a second embodiment of the self-weight supporting device of the present invention.

FIG. 6 is a view showing a tilt stage equipped with a conventional self-weight supporting device.

FIG. 7 is a diagram showing a drive system of a conventional self-weight supporting device.

[Explanation of symbols]

1, 201C, 201L: tilting stage, 2: tilting stage upper surface, 3: wafer, 4: horizontal guide, 5a, 5
b: self-weight support device, 6,206C, 206L: XY movable stage, 7: yoke, 8: permanent magnet, 9: coil, 1
0: coil holder, 11: yoke holder, 12: cooling pipe, 13: cylinder, 14: rolling seal, 1
5: piston, 16: air chamber, 17: air supply port, 1
8: air exhaust port, 19: air supply source, 20: servo valve, 21: throttle, 22: pressure gauge, 23: pressure signal line, 24: pressure controller, 25: linear motor controller, 100a, 100b: accelerometer, 101: acceleration signal, 102: conversion coefficient, 103: multiplier, 105
a, 105b: Z detecting means, 200: base, 300:
Linear motor part, 400: own weight support part.

Claims (12)

[Claims] 1. A drive means for moving a driven body in the direction of gravity from a base, a support means for supporting the weight of the driven body, a detection means for detecting displacement of the driven body with respect to the base in the direction of gravity, and In the self-weight supporting device having a control means for controlling the position of the driven body in the gravity direction based on the displacement value detected by the detection means, means for detecting an acceleration signal of the base in the gravity direction is provided and detected. A self-weight supporting device, wherein a value obtained by multiplying the acceleration signal by a conversion coefficient is fed back to the control means together with the displacement value. 2. A horizontal movable body having a driven body mounted thereon and held by the base so as to be movable in the horizontal direction with respect to the base, and a degree of freedom in the horizontal direction of the horizontal movable body is restricted, and other freedom is provided. A bearing for holding the driven body so as to be movable with respect to a degree, a drive means for moving in the gravity direction from the horizontal movable body,
Support means for supporting the weight of the driven body, a plurality of sets of detection means for detecting displacement of the driven body in the direction of gravity with respect to the horizontal movable body in the vicinity of the drive means, and displacement values detected by the detection means. In the self-weight supporting device having a control means for controlling the position or inclination of the driven body in the direction of gravity based on the above, means for detecting acceleration signals in the direction of gravity at a plurality of points on the horizontal movable body are provided and detected. A self-weight supporting device, wherein a value obtained by multiplying the acceleration signal by a predetermined conversion coefficient is fed back to the control means together with the displacement value. 3. A horizontal movable body having a driven body mounted thereon and held by the base so as to be movable in the horizontal direction with respect to the base, and a freedom degree in the horizontal direction with respect to the horizontal movable body is restricted, and other freedom is provided. A bearing for holding the driven body so as to be movable with respect to a degree, a drive means for moving in the gravity direction from the horizontal movable body,
Support means for supporting the weight of the driven body, a plurality of sets of detection means for detecting displacement of the driven body in the direction of gravity with respect to the horizontal movable body in the vicinity of the drive means, and displacement values detected by the detection means. In a gravity supporting device having a control means for controlling the position or inclination of the driven body in the direction of gravity based on the above, means for detecting acceleration signals in the direction of gravity at a plurality of points on the base are provided, and the detected acceleration A value obtained by multiplying a signal by a predetermined conversion coefficient is fed back to the control means together with the displacement value, and the conversion coefficient is a function of a horizontal position of the horizontal movable body on the base plate. apparatus. 4. The self-weight supporting device according to claim 2, wherein the force generated by the drive means and the force generated by the support means work coaxially. 5. The self-weight supporting device according to claim 2, wherein the bearing is a porous hydrostatic bearing. 6. The driven body is supported by a fixed guide having a cylindrical guide surface arranged on the horizontal movable body in the radial direction of the fixed guide via a fluid lubrication film. The weight supporting device according to any one of claims 2 to 4. 7. The self-weight supporting device according to claim 1, wherein the driving means is a linear motor, and the supporting means is an air cylinder. 8. The linear motor comprises a permanent magnet, a coil,
8. The self-weight support according to claim 7, further comprising: a member for holding the coil, and a pipe line for flowing a refrigerant on at least one of the member for holding the coil and the surface of the coil. apparatus. 9. The self-weight supporting device according to claim 7, wherein the air cylinder includes a cylinder, a piston, and a seal, and the seal is a rolling seal. 10. The self-weight supporting device according to claim 7, further comprising an adjusting device for adjusting the pressure in the air cylinder. 11. The self-weight supporting device according to claim 10, wherein the adjusting device uses the pressure in the air cylinder as a feedback signal. 12. The weight supporting device according to claim 10, wherein the adjusting device uses a current signal of the linear motor as a feedback signal.