Movable body drive method and movable body drive system, pattern formation method and apparatus, exposure method and apparatus, position control method and position control system, and device manufacturing method

• US 8,194,232 B2
• Filed: 07/18/2008
• Issued: 06/05/2012
• Est. Priority Date: 07/24/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Shibazaki, Yuichi, Kanaya, Yuho
• Primary Examiner(s): Glick, Edward
• Assistant Examiner(s): Asfaw, Mesfin T
• Application Number:
  US12/176,050
• Publication Number:
  US 20090027640A1
• Time in Patent Office: 1,418 Days
• Field of Search: 355/53, 355/72
• US Class Current: 355/72
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position

Abstract

Positional information of a movement plane of a wafer stage is measured using an encoder system such as, for example, an X head and a Y head, and the wafer stage is controlled based on the measurement results. At the same time, positional information of the wafer stage is measured using an interferometer system such as, for example, an X interferometer and a Y interferometer. When abnormality of the encoder system is detected or when the wafer stage moves off from a measurement area of the encoder system, drive control is switched to a drive control based on the measurement results of the interferometer system. Accordingly, drive control of the wafer stage can be performed continuously in the entire stroke area, even at the time when abnormality occurs in the encoder system.

Claims

1. A movable body drive system in which a movable body is driven at least in a uniaxial direction, the system comprising:

a laser interferometer which measures positional information of the movable body in the uniaxial direction at a first sampling interval;

an encoder which measures positional information of the movable body in the uniaxial direction at a second sampling interval;

a drive device which drives the movable body; and

a controller which drives the movable body in the uniaxial direction via the drive device based on measurement results of the encoder, and when detecting abnormality occurring in the encoder output, switches a measurement device used in position control of the movable body in the uniaxial direction from the encoder to the laser interferometer whose output coordinate has been corrected to be successive to an output of the encoder just before.

2. The movable body drive system according to claim 1, the system further comprising:

an update device which updates a difference between an output coordinate by the encoder and an output coordinate by the laser interferometer at every sampling interval of the encoder, wherein

when the controller detects abnormality occurring in the encoder output, by correcting the output coordinate of the laser interferometer at that time using the latest difference, the output coordinate of the laser interferometer is corrected to be successive to the output coordinate of the encoder just before.

3. The movable body drive system according to claim 1 wherein

after switching the measurement device used in the position control of the movable body in the uniaxial direction from the encoder to the laser interferometer, when the output of the encoder returns to a reliable degree, the controller switches the measurement device used in the position control of the movable body in the uniaxial direction from the laser interferometer to the encoder.

4. The movable body drive system according to claim 3 wherein

the controller performs the switching from the laser interferometer to the encoder by computing the output coordinate of the encoder during the switching, using an offset of a measurement unit computed based on the output coordinate of the laser interferometer and an offset of the encoder equal to or less than the measurement unit that has already been set.

5. The movable body drive system according to claim 1 wherein

when abnormality occurring in the encoder output is detected, an error-processing method to be performed can be specified to the controller.

6. The movable body drive system according to claim 5 wherein

as the error-processing method, one of showing a display encouraging manual assist, showing an alarm display that switching from the encoder to the laser interferometer has been performed, and not performing anything in particular can be specified alternatively.

7. A pattern formation apparatus that forms a pattern on an object, the apparatus comprising:

a patterning device which generates a pattern on the object; and

a movable body drive system according to claim 1, wherein

drive of a movable body on which the object is mounted is performed by the movable body drive system for pattern formation on the object.

8. The pattern formation apparatus according to claim 7 wherein

the object has a sensitive layer, and a pattern is generated on the object by an exposure of the sensitive layer by irradiation of an energy beam.

9. An exposure apparatus that forms a pattern on an object by an irradiation of an energy beam, the apparatus comprising:

a patterning device that irradiates the energy beam on the object; and

a movable body drive system according to claim 1, wherein

the movable body drive system drives the movable body on which the object is mounted for relative movement of the energy beam and the object.

10. A movable body drive system in which a movable body is driven in directions of three degree of freedom in a predetermined plane, the system comprising:

an interferometer system that measures positional information of the movable body in the directions of three degrees of freedom;

an encoder system that measures positional information of the movable body in the directions of three degrees of freedom;

a drive device which drives the movable body; and

a controller which performs a switching from servo control via the drive device of the position in the directions of three degrees of freedom of the movable body using the interferometer system to servo control via the drive device of the position in the directions of three degrees of freedom of the movable body using an encoder system by a phase linkage, where an output coordinate of the encoder system at the time of the switching is computed using an offset of a measurement unit computed based on the output coordinate of the interferometer system and an offset of the encoder system equal to or less than the measurement unit that has already been set for at least a rotational direction in the predetermined plane.

11. The movable body drive system according to claim 10 wherein

the controller performs a switching of the control by a coordinate linkage where an initial value of the output coordinate of the encoder system is set to coincide with the output coordinate of the interferometer system for directions of two degrees of freedom, excluding the rotational direction in the predetermined plane.

12. The movable body drive system according to claim 10 wherein

the movable body has a grating that has a grid arranged periodically in the uniaxial direction, and the encoder system has a head unit, which intersects a longitudinal direction of the grating and is placed substantially covering the whole area of the stroke of the movable body, including a plurality of head sections that are also placed at a spacing so that two adjacent head sections do not move off from the grating, whereby

the controller performs the phase linkage for the rotational direction in the predetermined plane, after having converted rotation quantity of the movable body measured by the interferometer system into rotation quantity between the two adjacent head sections of the head unit on the switching of the control.

13. A pattern formation apparatus that forms a pattern on an object, the apparatus comprising:

a patterning device which generates a pattern on the object; and

a movable body drive system according to claim 10, wherein

drive of a movable body on which the object is mounted is performed by the movable body drive system for pattern formation on the object.

14. The pattern formation apparatus according to claim 13 wherein

the object has a sensitive layer, and the patterning device generates a pattern on the object by an exposure of the sensitive layer by irradiation of an energy beam.

15. An exposure apparatus that forms a pattern on an object by an irradiation of an energy beam, the apparatus comprising:

a patterning device that irradiates the energy beam on the object; and

a movable body drive system according to claim 10, wherein

the movable body drive system drives the movable body on which the object is mounted for relative movement of the energy beam and the object.

16. A movable body drive system in which a movable body is driven at least in a uniaxial direction, the system comprising:

a laser interferometer which measures positional information of the movable body in the uniaxial direction;

an encoder which measures positional information of the movable body in the uniaxial direction;

a drive device which drives the movable body; and

a controller which performs switching from servo control via the drive device of the position of the movable body using the encoder to a control via the drive device of the position of the movable body using the laser interferometer when abnormality of the encoder is detected or when the movable body moves off from a measurement area of the encoder.

17. A pattern formation apparatus that forms a pattern on an object, the apparatus comprising:

a patterning device which generates a pattern on the object; and

a movable body drive system according to claim 16, wherein

drive of a movable body on which the object is mounted is performed by the movable body drive system for pattern formation on the object.

18. The pattern formation apparatus according to claim 17 wherein

the object has a sensitive layer, and the patterning device generates a pattern on the object by an exposure of the sensitive layer by irradiation of an energy beam.

19. An exposure apparatus that forms a pattern on an object by an irradiation of an energy beam, the apparatus comprising:

a patterning device that irradiates the energy beam on the object; and

a movable body drive system according to claim 16, wherein

the movable body drive system drives the movable body on which the object is mounted for relative movement of the energy beam and the object.

20. A movable body drive system in which a movable body is driven at least in a uniaxial direction, the system comprising:

a laser interferometer which measures positional information of the movable body in the uniaxial direction;

an encoder which measures positional information of the movable body in the uniaxial direction;

a drive device which drives the movable body; and

a controller which performs a coordinate linkage in the case of switching from servo control via the drive device of the position of the movable body using the encoder to control via the drive device of the position of the movable body using the laser interferometer, when abnormality occurring in the encoder output is detected, where an initial value of the output of the laser interferometer is set to coincide with the output coordinate of the encoder just before.

21. A pattern formation apparatus that forms a pattern on an object, the apparatus comprising:

a patterning device which generates a pattern on the object; and

a movable body drive system according to claim 20, wherein

drive of a movable body on which the object is mounted is performed by the movable body drive system for pattern formation on the object.

22. The pattern formation apparatus according to claim 21 wherein

the object has a sensitive layer, and the patterning device generates a pattern on the object by an exposure of the sensitive layer by irradiation of an energy beam.

23. An exposure apparatus that forms a pattern on an object by an irradiation of an energy beam, the apparatus comprising:

a patterning device that irradiates the energy beam on the object; and

a movable body drive system according to claim 20, wherein

the movable body drive system drives the movable body on which the object is mounted for relative movement of the energy beam and the object.

24. A position control system of a movable body in which a position of a movable body is controlled in at least a uniaxial direction, the system comprising:

a first measurement device which includes an encoder that generates information according to a position of the movable body in the uniaxial direction, and outputs a first positional information using an output from the encoder;

a second measurement device which includes a laser interferometer that irradiates a laser beam to the movable body in the uniaxial direction and generates a signal corresponding to an optical path length of the laser beam to the movable body in the uniaxial direction, and outputs a second positional information using an output from the laser interferometer;

a computing unit which obtains relation information between the first positional information and the second positional information; and

a controller which controls a position of the movable body using at least one of the first positional information and the second positional information, and when abnormality occurs in one of the first positional information and the second positional information used for the control of the movable body, the other positional information and the relation information obtained by the computing unit are used to control the position of the movable body.

25. The position control system according to claim 24 wherein

the computing unit obtains difference information of the first positional information and the second positional information as the relation information.

26. The position control system according to claim 24 wherein

the abnormality is a state where there is no output from one of the encoder and the laser interferometer.

27. The position control system according to claim 24 wherein

when abnormality occurs in one of the first positional information and the second positional information used for the control of the movable body, the controller begins position control of the movable body using the other positional information and the relation information obtained by the computing unit, and also begins the position control using the one positional information again at a predetermined timing.

28. The position control system according to claim 27 wherein

the controller includes a judgment section which judges abnormality cancellation of the one positional information after abnormality has occurred in one of the first positional information and the second positional information used for the control of the movable body, and

the predetermined timing in which the position control using the one positional information is started again is after when the judgment section judges abnormality cancellation in the one positional information.

29. The position control system according to claim 24 wherein

when abnormality occurs in one of the first positional information and the second positional information used for the control of the movable body, the controller encourages to select the control method of the movable body from a plurality of operation methods.

30. The position control system according to claim 24, the system further comprising:

an output device which outputs warning information when abnormality occurs in one of the first positional information and the second positional information used for the control of the movable body.

31. A position control system of a movable body in which a position of a movable body is controlled in at least a uniaxial direction, the system comprising:

a first measurement device which includes an encoder that generates information according to a position of the movable body in the uniaxial direction, and outputs positional information using an output from the encoder;

a second measurement device which includes a laser interferometer that irradiates a laser beam to the movable body in the uniaxial direction and generates a signal corresponding to an optical path length of the laser beam to the movable body in the uniaxial direction, and outputs positional information using an output from the laser interferometer; and

a controller which controls the position of the movable body using positional information output from the first measurement device, after having controlled the position of the movable body using positional information output from the second measurement device, whereby

when starting the position control of the movable body using the positional information output from the first measurement device, the controller adjusts the positional information output by the first measurement device using the positional information output from the second measurement device.

32. The position control system according to claim 31 wherein

the first measurement device and the second measurement device output a first coordinate information and a second coordinate information as the positional information, respectively, and

the controller adjusts the first coordinate information from the first measurement device which is obtained by using the output from the encoder so as to coincide with the second coordinate information from the second measurement device which is obtained by using the output from the laser interferometer.

33. The position control system according to claim 31 wherein

when starting the position control of the movable body using the positional information output from the first measurement device, the controller adjusts the positional information output by the first measurement device for at least a rotational direction within a movement plane of the movable body, using an offset of a measurement unit output from the second measurement device and an offset of the encoder system equal to or less than the measurement unit that has already been set.

34. The position control system according to claim 31 wherein

the first measurement device comprises a plurality of the encoders, and

as the output of the encoder used when starting the output of the positional information, the output from a specific encoder among the plurality of encoders is used.

35. An exposure apparatus that exposes an object held by a movable body with an energy beam, the apparatus comprising:

a first measurement device including an encoder, which measures positional information of the movable body;

a second measurement device including an interferometer, which measures positional information of the movable body; and

a controller that moves the movable body using one of the first and second measurement devices, and also decides positional information of the other of the measurement devices based on positional information of the one of the measurement devices, in order to control the movement by switching the one of the measurement devices to the other of the measurement devices during the movement.