Inspection device and inspecting method for spatial light modulator, illumination optical system, method for adjusting the illumination optical system, exposure apparatus, and device manufacturing method

• US 8,456,624 B2
• Filed: 11/22/2010
• Issued: 06/04/2013
• Est. Priority Date: 05/28/2008
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu, Tanaka, Hirohisa
• Primary Examiner(s): NGUYEN, TU T
• Application Number:
  US12/952,197
• Publication Number:
  US 20110069305A1
• Time in Patent Office: 925 Days
• Field of Search: 356/237.2
• US Class Current: 356/237.2
• CPC Class Codes: G01M 11/005 Testing of reflective surfaces, e.g. mirrors
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70591 Testing optical components

Abstract

There is disclosed an inspection device for inspecting a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, said inspection device comprising, a conjugate optical system which is arranged optically downstream the spatial light modulator and which forms a conjugate plane optically conjugate with an array plane where the plurality of optical elements are arrayed, a photodetector having a detection surface arranged on or near the conjugate plane, and an inspection unit which inspects optical characteristics of the plurality of optical elements, based on a result of detection by the photodetector.

Claims

1. An inspection device for inspecting a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, said inspection device comprising:

a conjugate optical system which is arranged optically downstream from the spatial light modulator and which forms a conjugate plane optically conjugate with an array plane where the plurality of optical elements are arrayed;

a first photodetector having a first detection surface arranged on or near the conjugate plane;

a Fourier transform optical system which is arranged optically downstream from the spatial light modulator and which forms a Fourier transform plane optically in a Fourier transform relation with the array plane where the plurality of optical elements are arrayed;

a second photodetector having a second detection surface arranged on or near the Fourier transform plane; and

an inspection unit which receives a first output of the first photodetector and a second output of the second photodetector and which inspects optical characteristics of the plurality of optical elements.

2. The inspection device according to claim 1 wherein the optical elements are mirror elements.

3. The inspection device according to claim 2, wherein the inspection unit inspects reflectances of the plurality of mirror elements, based on a light intensity distribution formed on the first detection surface through the conjugate optical system by light reflected on the plurality of mirror elements.

4. The inspection device according to claim 2, wherein the inspection unit inspects an operation of at least one mirror element, based on a light intensity distribution formed on the first detection surface by light reflected on the plurality of mirror elements in a first state of the plurality of mirror elements and a light intensity distribution formed on the first detection surface by light reflected on the plurality of mirror elements in a second state of the plurality of mirror elements in which a posture of a reflecting surface of said at least one mirror element is changed from the first state.

5. The inspection device according to claim 2, wherein the inspection unit inspects a change characteristic of a posture of at least one mirror element, based on a light intensity distribution formed on the second detection surface by light reflected on the plurality of mirror elements in a third state of the plurality of mirror elements and a light intensity distribution formed on the second detection surface by light reflected on the plurality of mirror elements in a fourth state of the plurality of mirror elements in which a posture of a reflecting surface of said at least one mirror element is changed from the third state.

6. The inspection device according to claim 2, wherein the inspection unit inspects a change characteristic of a posture of at least one mirror element, based on a light intensity distribution formed on the second detection surface by light reflected on the plurality of mirror elements in a first state of the plurality of mirror elements and a light intensity distribution formed on the second detection surface by light reflected on the plurality of mirror elements in a second state of the plurality of mirror elements in which a posture of a reflecting surface of said at least one mirror element is changed from the first state.

7. The inspection device according to claim 1, wherein a part of a plurality of optical members constituting the conjugate optical system belongs to the Fourier transform optical system.

8. The inspection device according to claim 1, wherein there is no optical element having an optical power in an optical path between the conjugate optical system and the first detection surface.

9. The inspection device according to claim 1, wherein optical members constituting the conjugate optical system are arranged along one optical axis.

10. The inspection device according to claim 1, which can be combined with an illumination optical system comprising a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, and illuminating an illumination target surface on the basis of illumination light from a light source,

the inspection device inspecting the spatial light modulator, based on the illumination light having traveled via at least a part of the plurality of optical elements of the spatial light modulator.

11. The inspection device according to claim 10, further comprising a splitting optical member which can be arranged in an optical path between the spatial light modulator and the illumination target surface and which splits the illumination light having traveled via at least a part of the plurality of optical elements of the spatial light modulator.

12. The inspection device according to claim 11, wherein the splitting optical member can be arranged in an optical path between a zoom optical system of the illumination optical system and the spatial light modulator.

13. The inspection device according to claim 11, wherein the splitting optical member can be arranged in an optical path between an integrator of the illumination optical system and the spatial light modulator.

14. The inspection device according to claim 1, which can be combined with an illumination optical system comprising a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, and illuminating an illumination target surface on the basis of illumination light from a light source,

the inspection device inspecting the spatial light modulator via a reflecting surface arranged between the conjugate optical system and the spatial light modulator and obliquely set with respect to an optical axis of the illumination optical system.

15. The inspection device according to claim 14, wherein each of the first and second photodetectors is obliquely set with respect to the optical axis of the conjugate optical system.

16. The inspection device according to claim 1, wherein each of the first and second photodetectors comprises a plurality of pixels and wherein a plurality of pixels correspond to one of the optical elements of the spatial light modulator.

17. The inspection device according to claim 1, the inspection device inspecting the spatial light modulator, based on a beam with a uniform light intensity distribution supplied to the plurality of optical elements of the spatial light modulator.

18. The inspection device according to claim 1, the inspection device inspecting the spatial light modulator, based on a beam with a nonuniform light intensity distribution supplied to a part of the plurality of optical elements of the spatial light modulator.

19. An illumination optical system which comprises a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually and which illuminates an illumination target surface on the basis of light from a light source, said illumination optical system comprising:

the inspection device as set forth in claim 1 for inspecting the spatial light modulator; and

a distribution forming optical system which forms a predetermined light intensity distribution on an illumination pupil of the illumination optical system, based on light having traveled via the spatial light modulator.

20. The illumination optical system according to claim 19, wherein the distribution forming optical system has an optical integrator, and a condensing optical system arranged in an optical path between the optical integrator and the spatial light modulator.

21. The illumination optical system according to claim 19, which is used in combination with a projection optical system for forming a plane optically conjugate with the illumination target surface, wherein the illumination pupil is a position optically conjugate with an aperture stop of the projection optical system.

22. An exposure apparatus comprising the illumination optical system as set forth in claim 19 for illuminating a predetermined pattern, wherein the predetermined pattern is transferred onto a photosensitive substrate to effect exposure thereof.

23. A device manufacturing method comprising:

transferring the predetermined pattern onto the photosensitive substrate to effect exposure thereof, using the exposure apparatus as set forth in claim 22;

developing the photosensitive substrate on which the predetermined pattern is transferred, to form a mask layer of a shape corresponding to the predetermined pattern on a surface of the photosensitive substrate; and

processing the surface of the photosensitive substrate through the mask layer.

24. A method for adjusting an illumination optical system which comprises a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually and which illuminates an illumination target surface on the basis of light from a light source, said method comprising:

inspecting optical characteristics of the plurality of optical elements, using the inspection device as set forth in claim 1; and

optically adjusting the illumination optical system, based on a result of the inspection.

25. An inspecting method for inspecting a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, said inspecting method comprising:

inspecting optical characteristics of the plurality of optical elements using a first photodetector and a second photodetector,

the first photodetector making a detection based on a light intensity distribution formed on or near a conjugate plane optically conjugate with an array plane where the plurality of optical elements are arrayed, by light having traveled via the plurality of optical elements, and

the second photodetector making a detection based on a light intensity distribution formed on or near a Fourier transform plane optically in a Fourier transform relation with the array plane, by light having traveled via the plurality of optical elements.

26. The inspecting method according to claim 25, wherein the optical elements are mirror elements.

27. The inspecting method according to claim 26, wherein the inspecting includes inspecting reflectances of the plurality of mirror elements, based on a light intensity distribution formed on or near the conjugate plane by light reflected on the plurality of mirror elements.

28. The inspecting method according to claim 26, wherein the inspecting includes inspecting a change characteristic of a posture of at least one mirror element, based on a light intensity distribution formed on or near the Fourier transform plane by light reflected on the plurality of mirror elements in a first state of the plurality of mirror elements and a light intensity distribution formed on or near the Fourier transform plane by light reflected on the plurality of mirror elements in a second state of the plurality of mirror elements in which a posture of a reflecting surface of said at least one mirror element is changed from the first state.

29. A method for adjusting an illumination optical system which comprises a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually and which illuminates an illumination target surface on the basis of light from a light source, said method comprising:

inspecting optical characteristics of the plurality of optical elements, using the inspecting method as set forth in claim 25; and

optically adjusting the illumination optical system, based on a result of the inspection.