Control method, control system, and program

• US 20080221709A1
• Filed: 09/15/2006
• Published: 09/11/2008
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Okita, Shinichi, Ishii, Yuuki
• Granted Patent: US 7,941,232 B2
• Time in Patent Office: Days
• US Class Current: 700/30
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G03F 7/70533 Controlling abnormal operating mode, e.g. taking account of waiting time, decision to rework or rework flow
• CPC Class Codes: G03F 7/70641 Focus
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load

Abstract

By repeatedly executing a predetermined measurement at set intervals, data on a predetermined performance (a best focus position) of a predetermined apparatus and data on variation factors of the performance are obtained (Steps 204 to 214). Based on the obtained data, multivariate analysis is performed and a model equation that is used to predict a variation amount of the performance and includes at least one of the variation factors as a variable is derived (Step 214). Therefore, after deriving the model equation, a variation amount of the performance can be predicted using the model equation by obtaining data on the variation factor that serves as the variable (Step 238). Accordingly, it becomes possible to maintain the performance described above with good accuracy in accordance with the prediction results and also optimize the implementation timing of maintenance and the like.

Claims

1. A control method in which a performance of a predetermined apparatus is controlled, the method comprising:

obtaining data related to a predetermined performance of the predetermined apparatus and data on variation factors of the performance by repeatedly executing a predetermined measurement at least one of at a set timing and at set intervals; and

deriving a model equation used to predict a variation amount of the performance that includes at least one of the variation factors as a variable, by performing multivariate analysis based on the obtained data.

2. The control method of claim 1, further comprising:

obtaining data on the variation factor that is the variable at a predetermined timing during operation of the predetermined apparatus, and computing a variation amount of the performance based on the obtained data and the model equation.

3. The control method of claim 2, further comprising:

executing the predetermined measurement at an implementation timing that is optimized based on the computed variation amount.

4. The control method of claim 3 wherein

the implementation timing is optimized so that an implementation interval of the predetermined measurement lengthens in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, and

the implementation timing is optimized so that an implementation interval of the predetermined measurement shortens in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance.

5. The control method of claim 2 wherein

a period of time required for the predetermined measurement is optimized based on a variation amount of the performance computed using the model equation.

6. The control method of claim 5 wherein

a period of time required for the predetermined measurement is shortened in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, and

a period of time required for the predetermined measurement is extended in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance.

7. The control method of claim 2, further comprising:

correcting the performance based on the computed variation amount.

8. The control method of claim 2 wherein

the number of the obtained data is optimized based on a variation amount of the performance computed using the model equation.

9. The control method of claim 8 wherein

in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, the number of the obtained data is decreased, and

in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance, the number of the obtained data is increased.

10. The control method of claim 1 wherein

the predetermined measurement is executed at the time of maintenance of the predetermined apparatus.

11. The control method of claim 1 wherein

the predetermined performance is at least one of an offset of a detection origin of a measurement unit that measures a positional relation between an image plane of a projection optical system and an object to be exposed with respect to an optical axis direction of the projection optical system, a best focus position of the projection optical system, and a focus offset of the projection optical system.

12. The control method of claim 11 wherein

the data related to the predetermined performance is data on at least one of an offset of the detection origin of the measurement unit and the best focus position, which are obtained as a result of executing at least one of measurement of an aerial image of a predetermined pattern and measurement of a transferred image of a predetermined pattern that is obtained as a result of a test exposure.

13. The control method of claim 11 wherein

the data related to the predetermined performance is data on at least one of an offset of the detection origin of the measurement unit and the best focus position, which are obtained based on data after conversion in which measurement data on the aerial image of the predetermined pattern is converted into measurement data on the transferred image of the predetermined pattern that is obtained as a result of the test exposure based on a known relation between the measurement data on the aerial image and the measurement data on the transferred image.

14. The control method of claim 1, wherein

the predetermined performance is a position control performance of a stage on which an object to be exposed is mounted.

15. A control system that controls a performance of a predetermined apparatus, the system comprising:

a data obtaining unit that obtains data related to a predetermined performance of the predetermined apparatus and data on variation factors of the performance by repeatedly executing a predetermined measurement at least one of at a set timing and at set intervals; and

a model equation deriving unit that derives a model equation used to predict a variation amount of the performance that includes at least one of the variation factors as a variable, by performing multivariate analysis based on the obtained data.

16. The control system of claim 15, further comprising:

a variation amount computing unit that obtains data on the variation factor that is the variable at a predetermined timing during operation of the predetermined apparatus, and computes a variation amount of the performance based on the obtained data and the model equation.

17. The control system of claim 16, further comprising:

a measurement executing unit that executes the predetermined measurement at an implementation timing that is optimized based on the computed variation amount.

18. The control system of claim 17 wherein

in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, the implementation timing is optimized so that an implementation interval of the predetermined measurement lengthens, and

in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance, the implementation timing is optimized so that an implementation interval of the predetermined measurement shortens.

19. The control system of claim 16 wherein

a period of time required for the predetermined measurement is optimized based on a variation amount of the performance computed using the model equation.

20. The control system of claim 19, further comprising:

a measurement time changing unit that shortens a period of time required for the predetermined measurement in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, and extends a period of time required for the predetermined measurement in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance.

21. The control system of claim 16, further comprising:

a correction unit that corrects the performance based on the computed variation amount.

22. The control system of claim 16 wherein

the number of the obtained data is optimized based on a variation amount of the performance computed using the model equation.

23. The control system of claim 22 wherein

in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, the number of the obtained data is decreased, and

in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance, the number of the obtained data is increased.

24. The control system of claim 15 wherein

the predetermined measurement is executed at the time of maintenance of the predetermined apparatus.

25. The control system of claim 15, further comprising:

a computer that online connects to the predetermined apparatus, wherein

at least a part of the data obtaining unit and the model equation deriving unit is arranged in one of the predetermined apparatus and the computer.

26. The control system of claim 15, further comprising:

an image measurement unit that online connects to the predetermined apparatus and measures a transferred image of a pattern that is formed on an object to be exposed, wherein

at least a part of the data obtaining unit and the model equation deriving unit is arranged in the image measurement unit.

27. The control system of claim 15, wherein

the predetermined performance is at least one of an offset of a detection origin of a measurement unit that measures a positional relation between an image plane of a projection optical system and an object to be exposed with respect to an optical axis direction of a projection optical system, a best focus position of the projection optical system, and a focus offset of the projection optical system.

28. A program that makes a computer that controls a performance of a predetermined apparatus execute a predetermined procedure, the program making the computer execute:

a procedure of obtaining data related to a predetermined performance of the predetermined apparatus and data on variation factors of the performance by repeatedly executing a predetermined measurement at least one of at a set timing and at set intervals; and

a procedure of deriving a model equation used to predict a variation amount of the performance that includes at least one of the variation factors as a variable, by performing multivariate analysis based on the obtained data.

29. The program of claim 28, further making the computer execute:

a procedure of obtaining data on the variation factor that is the variable at a predetermined timing during operation of the predetermined apparatus, and computing a variation amount of the performance based on the obtained data and the model equation.

30. The program of claim 29, further making the computer execute:

a procedure of executing the predetermined measurement at an implementation timing that is optimized based on the computed variation amount.

31. The program of claim 29, further making the computer execute:

a procedure of shortening a period of time required for the predetermined measurement in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, and extending a period of time required for the predetermined measurement in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance.

32. The program of claim 29, further making the computer execute:

a procedure of optimizing a period of time required for the predetermined measurement based on a variation amount of the performance computed using the model equation.

33. The program of claim 32, further making the computer execute:

a procedure of shortening a period of time required for the predetermined measurement in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, and extending a period of time required for the predetermined measurement in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance.

34. The program of claim 29, further making the computer execute:

a procedure of optimizing the number of the obtained data based on a variation amount of the performance computed using the model equation.

35. The program of claim 34, further making the computer execute:

a procedure of decreasing the number of the obtained data in the case a variation amount of the performance computed using the model equation does not exceed a value set in advance predetermined times in a row, and increasing the number of the obtained data in the case a variation amount of the performance computed using the model equation exceeds a permissible value set in advance.

36. The program of claim 28, wherein

the computer is made to execute the predetermined measurement at the time of maintenance of the predetermined apparatus.