Synchronous position control apparatus and method

• US 6,714,842 B1
• Filed: 05/25/2000
• Issued: 03/30/2004
• Est. Priority Date: 05/26/1999
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ito, Hiroshi
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): Rapp, Chad
• Application Number:
  US09/577,607
• Time in Patent Office: 1,405 Days
• Field of Search: 700/187, 700/188, 700/193, 700/194, 700/170, 700/13, 700/44, 700/45, 700/46, 700/63, 700/302, 318/560, 318/568.22, 318/570, 318/632, 318/638, 318/640, 318/651, 318/652
• US Class Current: 700/302
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70725 control
• CPC Class Codes: G05B 19/4142 characterised by the use of a microprocessor G05B19/4141 takes precedence
• CPC Class Codes: G05B 2219/45204 Die, mould making
• CPC Class Codes: G05B 2219/50218 Synchronize groups of axis, spindles

Abstract

A synchronous position control apparatus includes position controllers which perform control based on position feedback for a plurality of axes to be controlled, target position command value generators for respective axes which generate target position command values to be set in a respective position controller, and converters for respective axes which convert, on the basis of predetermined transfer functions, the target position command values for the respective axes that are output from the respective target position command value generators, and set the converted values in the respective position controllers. The characteristics of the transfer functions are set to substantially the same high-frequency cutoff characteristics for the respective axes, and the cutoff frequency of the transfer function is set to a smaller value than a servo band in any one position controller.

Claims

1. A synchronous position control apparatus comprising:

position controllers which perform control based on position feedback for a plurality of axes to be controlled;

target position command value generators for respective axes which generate target position command values to be set in a respective position controller; and

converters for respective axes which convert, on the basis of predetermined transfer functions, the target position command values for the respective axes that are output from the respective target position command value generators, and set the converted values in the respective position controllers,

wherein characteristics of the transfer functions are set to substantially the same high-frequency cutoff characteristics for the respective axes, and the cutoff frequency of the transfer function is set to a smaller value than a servo band in any one position controller.

2. The apparatus according to claim 1, further comprising prefilters inserted on input stages of the respective position controllers for the respective axes,

wherein characteristics of said prefilters are set to make transfer characteristics of combinations of said prefilters and said position controllers substantially the same for all the plurality of axes.

3. The apparatus according to claim 1, wherein the plurality of axes are two axes, and

the apparatus further comprises:

a coefficient multiplier which multiplies a tracking position along one of the two axes by a predetermined coefficient;

a corrector which obtains a correction value to be added to a position command value for one of the two axes on the basis of a synchronous error as a difference between the tracking position multiplied by the coefficient by said coefficient multiplier and a tracking position along another axis; and

an adder which adds the correction value obtained by said corrector to the position command value for one of the two axes.

4. The apparatus according to claim 3, wherein one of the two axes is a wafer stage in a scanning semiconductor exposure apparatus, and the other axis is a reticle stage in the semiconductor exposure apparatus.

5. A synchronous position control apparatus comprising:

an acceleration command value generator which generates target acceleration command values for a plurality of axes to be controlled;

compensators for the respective axes which convert the respective target acceleration command values in accordance with predetermined transfer functions, and output the converted values as converted acceleration command values;

integrators for the respective axes which integrate the respective converted acceleration command values twice, and output the integrated values as position command values;

correctors for the respective axes which perform predetermined compensation for the respective converted acceleration command values, and output the compensated values as feedforward signals; and

position controllers for performing control based on position feedback control for the respective axes on the basis of the respective position command values and the feedforward signals,

wherein characteristics of the transfer functions are set to be substantially the same high-frequency cutoff characteristics for the respective axes, and the cutoff frequency of the transfer function is set to a smaller value than a servo band in any one position controller.

6. The apparatus according to claim 5, wherein the plurality of axes are two axes, and

the apparatus further comprises:

a coefficient multiplier which multiplies a tracking position along one of the two axes by a predetermined coefficient;

a corrector which obtains a correction value to be added to the position command value for one of the two axes on the basis of a synchronous error as a difference between the tracking position multiplied by the coefficient by said coefficient multiplier and a tracking position along another axis; and

an adder which adds the correction value obtained by said corrector to the position command value for one of the two axes.

7. The apparatus according to claim 6, wherein one of the two axes is a wafer stage in a scanning semiconductor exposure apparatus, and the other axis is a reticle stage in the semiconductor exposure apparatus.

8. A synchronous position control method of performing synchronous position control by setting target position command values for position control mechanisms for performing control based on position feedback control for a plurality of axes to be controlled, said method comprising steps of:

converting the respective target position command values for the respective axes on the basis of predetermined transfer functions, and setting the converted values in the respective position control mechanisms; and

setting characteristics of the transfer functions to substantially the same high-frequency cutoff characteristics for the respective axes, and setting the cutoff frequency of the transfer function to a smaller value than a servo band in said any position control mechanism.

9. The method according to claim 8, wherein prefilters are inserted on input stages of the respective position control mechanisms for the respective axes, and

characteristics of the respective prefilters are set to make transfer characteristics of combinations of the prefilters and the position control mechanisms substantially the same for all the plurality of axes.

10. The method according to claim 8, wherein the plurality of axes are two axes, and

the method further comprises:

a coefficient multiplying step of multiplying a tracking position along one of the two axes by a predetermined coefficient;

a correction step of obtaining a correction value to be added to a position command value for one of the two axes on the basis of a synchronous error as a difference between the tracking position multiplied by the coefficient in said coefficient multiplying step and a tracking position along another axis; and

an addition step of adding the correction value obtained in said correction step to the position command value for one of the two axes.

11. The method according to claim 10, wherein one of the two axes is a wafer stage in a scanning semiconductor exposure apparatus, and the other axis is a reticle stage in the semiconductor exposure apparatus.

12. A synchronous position control method comprising:

an acceleration command value generation step of generating target acceleration command values for a plurality of axes to be controlled;

a conversion step of converting the respective target acceleration command values in accordance with predetermined transfer functions for the respective axes, and outputting the converted values as converted acceleration command values;

an integral step of integrating the respective converted acceleration command values twice, and outputting the integrated values as position command values for the respective axes;

a compensation step of performing predetermined compensation for the respective converted acceleration command values, and outputting the compensated values as feedforward signals for the respective axes; and

a position control step of performing control based on position feedback control for the respective axes on the basis of the position command values and the feedforward signals,

wherein characteristics of the transfer functions are set to substantially the same high-frequency cutoff characteristics for the respective axes, and the cutoff frequency of the transfer function is set to a smaller value than a servo band in said any position feedback control.

13. The method according to claim 12, wherein the plurality of axes are two axes, and

the method further comprises:

a coefficient multiplying step of multiplying a tracking position along one of the two axes by a predetermined coefficient;

a correction step of obtaining a correction value to be added to the position command value for one of the two axes on the basis of a synchronous error as a difference between the tracking position multiplied by the coefficient in said coefficient multiplying step and a tracking position along another axis; and

an addition step of adding the correction value obtained in said correction step to the position command value for one of the two axes.

14. The method according to claim 13, wherein one of the two axes is a wafer stage in a scanning semiconductor exposure apparatus, and the other axis is a reticle stage in the semiconductor exposure apparatus.

15. A position control apparatus comprising:

a first control loop for performing a first position feedback control for a first control axis;

a second control loop for performing a second position feedback control for a second control axis; and

plural prefilters set outside the first and second control loops so that transfer characteristics of the first and second control axes are substantially the same.

16. The position control apparatus according to claim 15, wherein the plural prefilters include a first prefilter set for the first control axis and a second prefilter set for the second control axis.

17. The position control apparatus according to claim 16, wherein characteristics of the first and second prefilters are set so that a transfer characteristic of a combination of the first control loop and the first prefilter is substantially the same as a transfer characteristic of a combination of the second control loop and the second prefilter.

18. The position control apparatus according to claim 16, wherein the first and second prefilters are set to substantially the same high-frequency cutoff characteristics.

19. The position control apparatus according to claim 15, wherein cutoff frequencies of the plural prefilters are smaller than servo bands of the first and second control loops.

20. The position control apparatus according to claim 19, wherein the plural prefilters include a first prefilter for the first control axis and a second prefilter for the second control axis.

21. The position control apparatus according to claim 20, wherein the first and second prefilters are set to substantially the same high-frequency cutoff characteristics.

22. The position control apparatus according to claim 15, wherein the first control axis is a wafer stage in a semiconductor exposure apparatus and wherein the second control axis is a reticle stage in the semiconductor exposure apparatus.

23. A position control method comprising the steps of:

performing a first position feedback control for a first control axis by a first control loop;

performing a second position feedback control for a second control axis by a second control loop; and

controlling transfer characteristics of the first and second control axes to be substantially the same by plural prefilters set outside the first and second control loops.

24. The position control method according to claim 23, wherein the plural prefilters include a first prefilter set for the first control axis and a second prefilter set for the second control axis.

25. The position control method according to claim 24, wherein characteristics of the first and second prefilters are set so that a transfer characteristic of a combination of the first control loop and the first prefilter is substantially the same as a transfer characteristic of a combination of the second control loop and the second prefilter.

26. The position control method according to claim 24, wherein the first and second prefilters are set to substantially the same high-frequency cutoff characteristics.

27. The position control method according to claim 23, wherein cutoff frequencies of the plural prefilters are smaller than servo bands of the first and second control loops.

28. The position control method according to claim 27, wherein the plural prefilters include a first prefilter for the first control axis and a second prefilter for the second control axis.

29. The position control method according to claim 28, wherein the first and second prefilters are set to substantially the same high-frequency cutoff characteristics.

30. The position control method according to claim 23, wherein the first control axis is a wafer stage in a semiconductor exposure apparatus and wherein the second control axis is a reticle stage in the semiconductor exposure apparatus.