OPTICAL UNIT, ILLUMINATION OPTICAL APPARATUS, EXPOSURE APPARATUS, AND DEVICE MANUFACTURING METHOD

• US 20090109417A1
• Filed: 10/03/2008
• Published: 04/30/2009
• Est. Priority Date: 10/24/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu
• Granted Patent: US 8,379,187 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: F21V 13/02 Combinations of only two kinds of elements
• CPC Class Codes: F21V 14/003 by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices
• CPC Class Codes: F21V 9/14 for producing polarised light
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0938 Using specific optical elements
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• 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 7/70566 Polarisation control

Abstract

An illumination optical apparatus has an optical unit. The optical unit has a light splitter to split an incident beam into two beams; a first spatial light modulator which can be arranged in an optical path of a first beam; a second spatial light modulator which can be arranged in an optical path of a second beam; and a light combiner which combines a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator; each of the first spatial light modulator and the second spatial light modulator has a plurality of optical elements arranged two-dimensionally and controlled individually.

Claims

1. An optical unit comprising:

a light splitter, arranged in an incident light path, to split an incident beam traveling in the incident light path, into a plurality of beams;

a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams;

a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams; and

a light combiner, arranged in an exiting light path, to combine a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator, and to direct a resultant beam to the exiting light path;

wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements arranged two-dimensionally and controlled individually; and

wherein the incident light path on the light splitter side and the exiting light path on the light combiner side extend in the same direction.

2. The optical unit according to claim 1, wherein said at least one spatial light modulator includes a plurality of mirror elements arranged two-dimensionally, and a drive unit to individually control and drive postures of the plurality of mirror elements.

3. The optical unit according to claim 2, wherein the drive unit continuously changes orientations of the plurality of mirror elements.

4. The optical unit according to claim 1, wherein the light splitter includes a polarization separating film.

5. The optical unit according to claim 4, wherein the light combiner includes a polarization separating film.

6. The optical unit according to claim 1, further comprising:

a first folding surface to fold the second beam having passed via the light splitter, toward the second spatial light modulator; and

a second folding surface to fold the second beam having passed via the second spatial light modulator, toward the light combiner.

7. The optical unit according to claim 1, wherein a light splitting surface of the light splitter and a light combining surface of the light combiner are provided at different positions.

8. The optical unit according to claim 1, wherein the first spatial light modulator can be arranged in a first space out of a plurality of spaces made by division by a plane including an axis connecting the incident light path and the exiting light path, and wherein the second spatial light modulator can be arranged in a second space different from the first space out of the plurality of spaces.

9. The optical unit according to claim 8, wherein the first spatial light modulator and the second spatial light modulator can be arranged at opposite positions on both sides of the axis.

10. The optical unit according to claim 1, wherein a traveling direction of the incident beam incident to the light splitter is parallel to a traveling direction in a standard state of the exiting beam exiting from the light combiner.

11. The optical unit according to claim 10, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source,

wherein the traveling direction in the standard state of the exiting beam is coincident with or parallel to an optical axis of the illumination optical apparatus.

12. The optical unit according to claim 1, wherein the light splitter and the light combiner include a common polarization beam splitter.

13. The optical unit according to claim 1, wherein the light splitter includes a diffractive optical element.

14. The optical unit according to claim 1, wherein the light splitter includes at least one prism.

15. The optical unit according to claim 14, further comprising a polarizer or an optical rotator which can be arranged in at least one of the optical path of the first beam and the optical path of the second beam between the light splitter and the light combiner.

16. The optical unit according to claim 14, wherein the light combiner includes an optical system to superimpose the beam having passed via the first spatial light modulator, and the beam having passed via the second spatial light modulator, on a predetermined surface.

17. The optical unit according to claim 1, wherein an angle of incidence of the incident beam to the light splitter is the Brewster'"'"'s angle.

18. The optical unit according to claim 1, wherein a path length difference is provided between light of the first beam traveling via the first spatial light modulator and light of the second beam traveling via the second spatial light modulator.

19. The optical unit according to claim 1, wherein the incident beam has such a sectional shape that a length along a first direction in a cross section of the incident beam is smaller than a length along a second direction perpendicular to the first direction, and

wherein the light splitter splits the incident beam along the first direction.

30. The optical unit according to claim 1, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the optical unit guiding light to a distribution forming optical system in the illumination optical apparatus in order to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus.

31. An illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the illumination optical apparatus comprising:

the optical unit as set forth in claim 1; and

a distribution forming optical system to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus, based on the beams having passed via the first and second spatial light modulators.

32. An exposure apparatus comprising the illumination optical apparatus as set forth in claim 31, for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

33. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus as set forth in claim 32;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, to form a mask layer in 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.

34. The optical unit according to claim 19, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the optical unit guiding light to a distribution forming optical system in the illumination optical apparatus in order to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus.

35. An illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the illumination optical apparatus comprising:

the optical unit as set forth in claim 19; and

a distribution forming optical system to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus, based on the beams having passed via the first and second spatial light modulators.

36. An exposure apparatus comprising the illumination optical apparatus as set forth in claim 35, for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

37. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus as set forth in claim 36;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, to form a mask layer in 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.

20. An optical unit comprising:

a light splitter, arranged in a path of an incident beam, to split the incident beam into a plurality of beams in mutually different polarization states;

a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams;

a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams; and

a light combiner, arranged in a path of a beam having passed via the first spatial light modulator and a path of a beam having passed via the second spatial light modulator, to combine the beam having passed via the first spatial light modulator, with the beam having passed via the second spatial light modulator;

wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements arranged two-dimensionally and controlled individually.

21. An optical unit comprising:

a light splitter, arranged in a path of an incident beam, to split the incident beam into a plurality of beams;

a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams;

a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams; and

a light combiner, arranged in a path of a beam having passed via the first spatial light modulator and a path of a beam having passed via the second spatial light modulator, to combine the beam having passed via the first spatial light modulator, with the beam having passed via the second spatial light modulator;

wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements arranged two-dimensionally and controlled individually;

wherein the incident beam has such a sectional shape that a length along a first direction in a cross section of the incident beam is smaller than a length along a second direction perpendicular to the first direction, and

wherein the light splitter splits the incident beam along the first direction.

38. The optical unit according to claim 21, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the optical unit guiding light to a distribution forming optical system in the illumination optical apparatus in order to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus.

39. An illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the illumination optical apparatus comprising:

the optical unit as set forth in claim 21; and

a distribution forming optical system to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus, based on the beams having passed via the first and second spatial light modulators.

40. An exposure apparatus comprising the illumination optical apparatus as set forth in claim 39, for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

41. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus as set forth in claim 40;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, to form a mask layer in 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.

22. An optical unit to be used together with an optical system having a predetermined optical axis, the optical unit comprising:

a light splitter which can be arranged in an optical path of the optical system and which splits an incident beam into a plurality of beams;

a first spatial light modulator which can be arranged at a first position being a position in an optical path of a first beam out of the plurality of beams and position different from the predetermined optical axis;

a second spatial light modulator which can be arranged at a second position being a position in an optical path of a second beam out of the plurality of beams and position different from the predetermined optical axis; and

a light combiner which can be arranged in the optical path of the optical system and which combines a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator;

wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements arranged two-dimensionally and controlled individually; and

wherein the first position and the second position are positions off the predetermined optical axis of the optical system.

23. The optical unit according to claim 22, wherein the first spatial light modulator can be arranged in a first space out of a plurality of spaces made by division by a plane including the predetermined optical axis, and

wherein the second spatial light modulator can be arranged in a second space different from the first space out of the plurality of spaces.

24. The optical unit according to claim 22, wherein the first spatial light modulator and the second spatial light modulator can be arranged at opposite positions on both sides of the predetermined optical axis.

42. The optical unit according to claim 22, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the optical unit guiding light to a distribution forming optical system in the illumination optical apparatus in order to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus.

43. An illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the illumination optical apparatus comprising:

the optical unit as set forth in claim 22; and

a distribution forming optical system to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus, based on the beams having passed via the first and second spatial light modulators.

44. An exposure apparatus comprising the illumination optical apparatus as set forth in claim 43, for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

45. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus as set forth in claim 44;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, to form a mask layer in 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.

25. An optical unit to be used together with an optical system having a predetermined optical axis, the optical unit comprising:

a first reflecting surface which can be arranged in an optical path of the optical system and which reflects light incident in parallel with the optical axis of the optical system;

a first spatial light modulator which can be arranged in optical path of the light reflected on the first reflecting surface;

a second reflecting surface which can be arranged in a path of light having passed via the first spatial light modulator and which reflects the light having passed via the first spatial light modulator, and emit the reflected light into the optical system;

a third reflecting surface which can be arranged in an optical path of the optical system and which reflects light incident in parallel with the optical axis of the optical system;

a second spatial light modulator which can be arranged in an optical path of the light reflected on the third reflecting surface; and

a fourth reflecting surface which can be arranged in a path of light having passed via the second spatial light modulator and which reflects the light having passed via the second spatial light modulator, and emit the reflected light into the optical system;

wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements arranged two-dimensionally and controlled individually.

26. The optical unit according to claim 25, wherein the first to fourth reflecting surfaces are obliquely arranged with respect to the predetermined optical axis of the optical system.

27. The optical unit according to claim 26, wherein the first spatial light modulator can modulate light in such a manner that the light reflected on the second reflecting surface to be emitted into the optical system becomes parallel to the light incident to the first reflecting surface, and

wherein the second spatial light modulator can modulate light in such a manner that the light reflected on the fourth reflecting surface to be emitted into the optical system becomes parallel to the light incident to the third reflecting surface.

28. The optical unit according to claim 27,

wherein the first reflecting surface is located on a first plane,

wherein the second reflecting surface is located on a second plane intersecting with the first plane,

wherein the third reflecting surface is located on a third plane, and

wherein the fourth reflecting surface is located on a fourth plane intersecting with the third plane.

29. The optical unit according to claim 28, wherein a ridge line made by the first and second planes is provided on the first spatial light modulator side with respect to the first and second reflecting surfaces,

wherein a ridge line made by the third and fourth planes is provided on the second spatial light modulator side with respect to the third and fourth reflecting surfaces, and

wherein an angle between the first and second reflecting surfaces is an obtuse angle and an angle between the third and fourth reflecting surfaces is an obtuse angle.

46. The optical unit according to claim 25, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the optical unit guiding light to a distribution forming optical system in the illumination optical apparatus in order to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus.

47. An illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the illumination optical apparatus comprising:

the optical unit as set forth in claim 25; and

a distribution forming optical system to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus, based on the beams having passed via the first and second spatial light modulators.

48. An exposure apparatus comprising the illumination optical apparatus as set forth in claim 47, for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

49. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus as set forth in claim 48;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, to form a mask layer in 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.