Exposure method, exposure apparatus, and device manufacturing method

• US 8,488,109 B2
• Filed: 08/20/2010
• Issued: 07/16/2013
• Est. Priority Date: 08/25/2009
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Shibazaki, Yuichi
• Primary Examiner(s): Nguyen, Hung Henry
• Assistant Examiner(s): KREUTZER, COLIN WRIGHT
• Application Number:
  US12/860,299
• Publication Number:
  US 20110051108A1
• Time in Patent Office: 1,061 Days
• Field of Search: 310 1205- 1206, 355/53, 355/72, 355/75, 355/77, 356399-401, 356614-624
• US Class Current: 355/77
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

Positional information of a stage is obtained using an interferometer system only during an exposure time when a constant speed drive of the stage is performed to form a pattern. Therefore, the linear measurement of the positional information is secured enough, which makes it possible to linearly drive the stage with high accuracy. Meanwhile, between an acceleration time and a deceleration time in which a step drive is performed, the positional information of the stage is obtained using an encoder system and a surface position measurement system. Therefore, measurement reproducibility of the positional information is sufficiently secured by the mechanical stability of a diffraction grating, which makes it possible to drive the stage precisely to the starting position of the constant speed drive.

Claims

1. An exposure method in which a pattern is sequentially formed on a plurality of shot areas arranged on an object, the method comprising:

measuring a positional information of a movable body which moves along a predetermined plane holding the object by a first measurement system which irradiates a first measurement beam on a first measurement plane and receives a reflected beam, and performing a constant speed drive of the movable body in a scanning direction to form the pattern in each of the plurality of shot areas using the measurement results of the first measurement system;

measuring a positional information of the movable body by a second measurement system which irradiates a second measurement beam on a second measurement plane different from the first measurement plane, and receives a reflected beam, and performing a stepping drive of the movable body toward a starting position of the constant speed drive to form the pattern in each of the plurality of shot areas using the measurement results of the second measurement system; and

switching a measurement system which obtains the positional information used to drive the movable body from one of the first measurement system and the second measurement system to the other of the first measurement system and the second measurement system, in accordance with whether the constant speed drive or the stepping drive is being performed.

2. The exposure method according to claim 1, the method further comprising:

switching the measurement system which obtains the positional information used to drive the movable body from the second measurement system to the first measurement system, before the constant speed drive is performed.

3. The exposure method according to claim 2, the method further comprising:

making an offset used to reset measurement results of the first measurement system using measurement results of the first and second measurement systems, and resetting the measurement results of the first measurement system using the offset, prior to switching the measurement system.

4. The exposure method according to claim 3 wherein

the offset is made by time averaging a difference between the measurement results of the first and second measurement systems.

5. The exposure apparatus according to claim 3 wherein

the offset is made by collecting the measurement results of the first and second measurement systems for each predetermined time, and applying moving averaging to the difference of the measurement results which have been collected.

6. The exposure method according to claim 4 wherein

the measurement results of the first measurement system are reset using the offset, after the offset is converged.

7. The exposure method according to claim 6 wherein

the measurement results of the first measurement system are reset when a difference of the measurement results of the first and second measurement systems coincides with the offset which has been converged.

8. The exposure method according to claim 3 wherein

the measurement results of the first measurement system are reset so that the measurement results coincide with the measurement results of the second measurement system.

9. The exposure method according to claim 3 wherein

the measurement results of the first measurement system are reset while the movable body is being moved at a constant speed.

10. The exposure method according to claim 3, the method further comprising:

correcting measurement errors of the first measurement system which are caused due to acceleration of the movable body, wherein

the measurement results of the first measurement system are reset while the movable body is accelerated.

11. The exposure method according to claim 1 wherein

an optical path length of the second measurement beam reaching the second measurement plane is set shorter than an optical path length of the first measurement beam reaching the first measurement plane.

12. The exposure method according to claim 1 wherein

the first measurement plane is a reflection surface provided on the movable body, and

the first measurement system includes an interferometer system which obtains positional information of the movable body by irradiating the first measurement beam on the reflection surface and receiving a reflected beam from the reflection surface.

13. The exposure method according to claim 1 wherein

the second measurement plane is a measurement plane which is parallel to the predetermined plane provided on at least one of the movable body and an outside of the movable body, and has a diffraction grating on a surface, and

the second measurement system includes an encoder system which obtains positional information in a predetermined measurement direction of the movable body by irradiating the second measurement beam on the second measurement plane from the other of the movable body and an outside of the movable body, and receiving a diffraction beam from the diffraction grating.

14. The exposure method according to claim 13 wherein

the encoder system obtains positional information of the movable body in at least one direction of a direction parallel to the predetermined plane, a perpendicular direction with respect to the predetermined plane, and a tilt direction with respect to the predetermined plane.

15. The exposure method according to claim 1 wherein

the first measurement system is superior in linearity of measurement values to the second measurement system.

16. The exposure method according to claim 1 wherein

the first measurement system is superior in long-term stability of measurement values to the second measurement system.

17. The exposure method according to claim 1 wherein

the first measurement system is slower in temporal change of output signals at the time of abnormality generation than the second measurement system.

18. The exposure method according to claim 1 wherein

the second measurement system is smaller in short-term variation of measurement values than the first measurement system.

19. The exposure method according to claim 1 wherein

the second measurement system is superior in measurement accuracy to the first measurement system.

20. The exposure method according to claim 1 wherein

the second measurement system is superior in measurement reproducibility to the first measurement system.

21. The exposure method according to claim 1, the method further comprising:

switching the measurement system which obtains the positional information used to drive the movable body from the first measurement system to the second measurement system, after the constant speed drive is performed.

22. The exposure method according to claim 1 wherein

the pattern is formed on the object by projecting an energy beam via a mask on which the pattern is formed and an optical system, and

in the formation, position alignment of the pattern to each of the plurality of shot areas is performed by driving an optical element which configures the optical system.

23. The exposure method according to claim 1 wherein

the pattern is formed on the object by performing a relative drive of a mask on which the pattern is formed and the object, and

in the formation, position alignment of the pattern to each of the plurality of shot areas is performed by adjusting the relative drive.

24. A device manufacturing method, including

forming a pattern on an object by the exposure method according to claim 1;

and

developing the object on which the pattern is formed.

25. An exposure apparatus which sequentially forms a pattern on a plurality of shot areas arranged on an object, the apparatus comprising:

a movable body which holds the object and moves along a predetermined plane;

a first measurement system which measures positional information of the movable body by irradiating a first measurement beam on a first measurement plane and receiving a reflected beam;

a second measurement system which measures positional information of the movable body by irradiating a second measurement beam on a second measurement plane different from the first measurement plane and receiving a reflected beam; and

a control system which performs a constant speed drive of the movable body in a scanning direction to form the pattern in each of the plurality of shot areas using measurement results of the first measurement system, and performs a step drive of the movable body toward a starting position of the constant speed drive to form the pattern in each of the plurality of shot areas using measurement results of the second measurement system, wherein

the control system switches a measurement system that obtains the positional information used to drive the movable body from one of the first measurement system and the second measurement system to the other of the first measurement system and the second measurement system, in accordance with whether the control system performs the constant speed drive or the stepping drive.

26. The exposure apparatus according to claim 25 wherein

the control system switches the measurement system which obtains the positional information used to drive the movable body from the second measurement system to the first measurement system, before the constant speed drive is performed.

27. The exposure apparatus according to claim 26 wherein

the control system makes an offset used to reset measurement results of the first measurement system using measurement results of the first and second measurement systems, and resets the measurement results of the first measurement system using the offset, prior to switching the measurement system.

28. The exposure apparatus according to claim 26 wherein

the control system switches the measurement system which obtains the positional information used to drive the movable body from the first measurement system to the second measurement system, after the constant speed drive is performed.

29. The exposure apparatus according to claim 25 wherein

an optical path length of the second measurement beam reaching the second measurement plane is set shorter than an optical path length of the first measurement beam reaching the first measurement plane.

30. The exposure apparatus according to claim 25 wherein

the first measurement plane is a reflection surface provided on the movable body, and

the first measurement system includes an interferometer system which obtains positional information of the movable body by irradiating the first measurement beam on the reflection surface and receiving a return beam from the reflection surface.

31. The exposure apparatus according to claim 25 wherein

the second measurement plane is a measurement plane which is parallel to the predetermined plane provided on at least one of the movable body and an outside of the movable body, and has a diffraction grating on a surface, and

the second measurement system includes an encoder system which obtains positional information in a predetermined measurement direction of the movable body by irradiating the second measurement beam on the second measurement plane from the other of the movable body and an outside of the movable body, and receiving a diffraction beam from the diffraction grating.

32. The exposure apparatus according to claim 31 wherein

the encoder system obtains positional information of the movable body in at least one direction of a direction parallel to the predetermined plane, a perpendicular direction with respect to the predetermined plane, and a tilt direction with respect to the predetermined plane.

33. The exposure apparatus according to claim 25 wherein

the first measurement system is superior in linearity of measurement values to the second measurement system.

34. The exposure apparatus according to claim 25 wherein

the first measurement system is superior in long-term stability of measurement values to the second measurement system.

35. The exposure apparatus according to claim 25 wherein

the first measurement system is slower in temporal change of output signals at the time of abnormality generation than the second measurement system.

36. The exposure apparatus according to claim 25 wherein

the second measurement system is smaller in short-term variation of measurement values than the first measurement system.

37. The exposure apparatus according to claim 25 wherein

the second measurement system is superior in measurement accuracy to the first measurement system.

38. The exposure apparatus according to claim 25 wherein

the second measurement system is superior in measurement reproducibility to the first measurement system.

39. The exposure apparatus according to claim 25, the apparatus further comprising:

an optical system which projects an image of the pattern on the object, wherein

the control system performs position alignment of the pattern to each of the plurality of shot areas by driving an optical element which configures the optical system.

40. The exposure apparatus according to claim 25, the apparatus further comprising:

another movable body which moves holding a mask on which the pattern is formed, wherein

the control system performs position alignment of the pattern to each of the plurality of shot areas by adjusting a relative drive of the another movable body and the movable body.

41. A device manufacturing method, including

forming a pattern on an object using the exposure apparatus according to claim 25;

and

developing the object on which the pattern is formed.

42. A making method of an exposure apparatus which sequentially forms a pattern on a plurality of shot areas arranged on an object, the method comprising:

providing a movable body which holds the object and moves along a predetermined plane;

providing a first measurement system which measures positional information of the movable body by irradiating a first measurement beam on a first measurement plane and receiving a reflected beam;

providing a second measurement system which measures positional information of the movable body by irradiating a second measurement beam on a second measurement plane different from the first measurement plane and receiving a reflected beam; and

providing a control system which performs a constant speed drive of the movable body in a scanning direction to form the pattern in each of the plurality of shot areas using measurement results of the first measurement system, and performs a step drive of the movable body toward a starting position of the constant speed drive to form the pattern in each of the plurality of shot areas using measurement results of the second measurement system, wherein

the control system switches a measurement system that obtains the positional information used to drive the movable body from one of the first measurement system and the second measurement system to the other of the first measurement system and the second measurement system, in accordance with whether the control system performs the constant speed drive or the step drive.