ILLUMINATION OPTICAL SYSTEM, EXPOSURE APPARATUS, DEVICE PRODUCTION METHOD, AND LIGHT POLARIZATION UNIT

• US 20140233008A1
• Filed: 11/25/2011
• Published: 08/21/2014
• Est. Priority Date: 06/07/2011
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu, Tanaka, Hirohisa, Kato, Kinya, Mori, Takashi
• Granted Patent: US 9,599,905 B2
• Time in Patent Office: Days
• US Class Current: 355/71
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• 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 7/0007 Filters, e.g. additive colour filters; Components for display devices
• 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 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• CPC Class Codes: G03F 7/70566 Polarisation control

Abstract

An illumination optical system which illuminates an illumination objective surface with a light from a light source. The illumination optical system includes a spatial light modulator which includes a plurality of optical elements arranged within a predetermined plane and controlled individually, and which forms a light intensity distribution in an illumination pupil of the illumination optical system; and a polarization unit which is arranged in a position optically conjugate with the predetermined plane, and which polarizes an incident light beam having a first and second partial light beams, coming into the polarization unit such that the first and second partial light beams have polarization states different from each other, and emits the polarized incident light beam as an outgoing light beam, wherein the polarization unit changes, in a cross section of the outgoing light beam, a ratio between a cross sectional areas of the first and second partial light beams.

Claims

1. An illumination optical system which illuminates an illumination objective surface with a light from a light source, the illumination optical system comprising:

a spatial light modulator which includes a plurality of optical elements arranged within a predetermined plane and controlled individually, and which forms a light intensity distribution in a variable manner in an illumination pupil of the illumination optical system; and

a polarization unit which is arranged in a conjugate position optically conjugate with the predetermined plane in an optical path of the illumination optical system, and which polarizes an incident light beam having a first partial light beam and a second partial light beam different from the first partial light beam, coming into the polarization unit such that the first partial light beam and the second partial light beam have polarization states different from each other, and emits the polarized incident light beam as an outgoing light beam,

wherein the polarization unit changes, in a cross section of the outgoing light beam, a ratio between a cross sectional area of the first partial light beam and a cross sectional area of the second partial light beam.

2. The illumination optical system according to claim 1, wherein the polarization unit is arranged in the conjugate position in the optical path on the illumination objective surface side with respect to the spatial light modulator.

3. The illumination optical system according to claim 2, wherein a light in a polarization state in which a linearly polarized light is a main component passes through the optical path on the light source side with respect to the polarization unit.

4. The illumination optical system according to claim 3, wherein a polarization direction of the linearly polarized light is a direction along a plane including optical axes on the light source side with respect to an arrangement plane of the spatial light modulator and on the illumination objective surface side with respect to the arrangement plane of the spatial light modulator or a direction orthogonal to the plane including the optical axes.

5. The illumination optical system according to claim 1, wherein the polarization unit has a first optical element which changes the polarization state of the second partial light beam in the incident light beam, the second partial light beam being different from the first partial light beam, without exerting any effect on the first partial light beam in the incident light beam.

6. The illumination optical system according to claim 5, wherein the first optical element is arranged on a first plane along a cross section of the incident light beam, and configured to be movable along the first plane for changing the ratio between the cross-sectional area of the first partial light beam via the first plane and the cross-sectional area of the second partial light beam via the first plane.

7. The illumination optical system according to claim 5, wherein the first optical element has a pair of edges extending in a first direction parallel to one pair of sides of a rectangular cross section of the incident light beam, and is movable in a second direction orthogonal to the first direction.

8. The illumination optical system according to claim 5, wherein the first optical element has a first edge extending in a third direction obliquely intersecting one pair of sides of a rectangular cross section of the incident light beam, and a second edge extending in a fourth direction different from the third direction, and is movable two-dimensionally along the cross section of the incident light beam.

9. The illumination optical system according to claim 8, wherein the fourth direction in which the second edge of the first optical element extends is a direction obliquely intersecting the one pair of sides.

10. The illumination optical system according to claim 5, wherein the polarization unit has a second optical element which changes a polarization state of a third partial light beam which is at least part of the second partial light beam via the first optical element, and a polarization state of a fourth partial light beam which is at least part of the first partial light beam coming into the second optical element without passing through the first optical element.

11. The illumination optical system according to claim 10, wherein the second optical element is arranged on a second plane along the cross section of the incident light beam, and configured to be movable along the second plane for changing a ratio between a cross-sectional area of the third partial light beam via the second plane and a cross-sectional area of the fourth partial light beam via the second plane.

12. The illumination optical system according to claim 10, wherein the second optical element has a pair of edges extending in a first direction parallel to one pair of sides of a rectangular cross section of the incident light beam, and is movable in a second direction orthogonal to the first direction.

13. The illumination optical system according to claim 10, wherein the second optical element has a third edge extending in a fifth direction obliquely intersecting one pair of sides of a rectangular cross section of the incident light beam, and a fourth edge extending in a sixth direction different from the fifth direction, and is movable two-dimensionally along the cross section of the incident light beam.

14. The illumination optical system according to claim 13, wherein the sixth direction in which the fourth edge of the second optical element extends is a direction obliquely intersecting the one pair of sides.

15. The illumination optical system according to claim 5, wherein the first optical element includes a polarization rotation member which rotates the polarization direction of the incident light beam with linear polarization by a predetermined angle, and then emits the incident light beam as the outgoing light beam.

16. The illumination optical system according to claim 5, wherein the first optical element has an optical rotation member formed of an optical material having optical rotation property.

17. The illumination optical system according to claim 10, wherein at least one of the first optical element and the second optical element includes a polarization rotation member which rotates the polarization direction of the incident light beam with linear polarization by a predetermined angle, and then emits the incident light beam as the outgoing light beam.

18. The illumination optical system according to claim 10, wherein at least one of the first optical element and the second optical element includes an optical rotation member formed of an optical material having optical rotation property.

19. The illumination optical system according to claim 16, wherein the optical rotation member comprises a first optical rotation member formed of a clockwise optical rotation material, and a second optical rotation member formed of a counterclockwise optical rotation material and arranged adjacent to the first optical rotation member.

20. The illumination optical system according to claim 18, wherein a phase difference imparting member which imparts the incident light beam with phase differences which are different based on an incident position of the incident light beam is arranged on an optical Fourier transform plane of the predetermined plane.

21. The illumination optical system according to claim 5, wherein the first optical element includes a wave plate which changes the incident light beam into a light in a predetermined polarization state.

22. The illumination optical system according to claim 10, wherein at least one of the first optical element and the second optical element includes a wave plate which changes the incident light beam into a light in a predetermined polarization state.

23. The illumination optical system according to claim 21, wherein the wave plate is rotatable along a cross section of the incident light beam.

24. The illumination optical system according to claim 22, wherein the wave plate comprises a first wave plate having an optic axis along a first direction within a plane along the cross section of the incident light beam, and a second wave plate having an optic axis along a second direction different from the first direction within the plane along the cross section of the incident light beam.

25. The illumination optical system according to claim 10, wherein at least one of the first optical element and the second optical element includes a polarizer which selects a light in a predetermined polarization state from the incident light beam and then emits the selected light.

26. The illumination optical system according to claim 10, wherein the first optical element and the second optical element are arranged adjacent to each other.

27. The illumination optical system according to claim 1, further comprising a relay optical system arranged between the predetermined plane and a position conjugate with the predetermined plane.

28. The illumination optical system according to claim 27, wherein the first optical element and the second optical element are arranged across the position optically conjugate with the predetermined plane.

29. The illumination optical system according to claim 27, wherein the position optically conjugate with the predetermined plane is a position on an optical axis of the relay optical system.

30. The illumination optical system according to claim 27, wherein the predetermined plane on which the plurality of optical elements of the spatial light modulator are arranged is inclined with respect to a plane orthogonal to an optical axis of the relay optical system;

and the first optical element is configured to be movable in a direction along a plane optically conjugate with the predetermined plane with respect to the relay optical system.

31. The illumination optical system according to claim 10, further comprising a second relay optical system which is arranged between the first optical element and the second optical element, and which sets the first optical element and the second optical element optically conjugate with each other.

32. The illumination optical system according to claim 1, wherein the polarization unit has a depolarizing element insertable to and removable from the illumination optical path.

33. The illumination optical system according to claim 32, wherein the depolarizing element is insertable and removable at a position optically conjugate with the predetermined plane in the illumination optical path, or in the vicinity of the position optically conjugate with the predetermined plane.

34. The illumination optical system according to claim 1, further comprising an optical integrator, wherein the polarization unit is arranged in an optical path between the spatial light modulator and the optical integrator.

35. The illumination optical system according to claim 1, wherein the spatial light modulator includes a plurality of mirror elements arranged two-dimensionally within the predetermined plane, and a drive portion which controls and drives attitudes of the plurality of mirror elements individually.

36. The illumination optical system according to claim 35, wherein the drive portion changes orientations of the plurality of mirror elements continuously or discretely.

37. The illumination optical system according to claim 35, wherein in a case that a group of mirror elements positioned in a first region on the predetermined plane, among the plurality of mirror elements, is defined as a first mirror element group, and that a group of mirror elements positioned in a second region different from the first region on the predetermined plane, among the plurality of mirror elements, is defined as a second mirror element group, the drive portion controls and drives the first mirror element group such that a light via the first mirror element group is guided to a first pupil region on an optical Fourier transform plane of the predetermined plane, and controls and drives the second mirror element group such that a light via the second mirror element group is guided to a second pupil region on the optical Fourier transform plane of the predetermined plane.

38. The illumination optical system according to claim 37, wherein the first pupil region is different from the second pupil region.

39. The illumination optical system according to claim 37, wherein the first pupil region partially overlaps the second pupil region.

40. The illumination optical system according to claim 37, wherein the polarization unit includes a first optical element which changes a polarization state of the second partial light beam via the second mirror element group without exerting any effect on the first partial light beam via the first mirror element group.

41. The illumination optical system according to claim 1, wherein the polarization unit is arranged in the conjugate position in the optical path on the light source side with respect to the spatial light modulator.

42. The illumination optical system according to claim 41, further comprising an illuminance uniformization optical system which is arranged in the optical path on the light source side with respect to the conjugate position, and improves an illuminance uniformity within a plane including the conjugate position to be higher than an illuminance uniformity within a cross section of the incident light beam.

43. The illumination optical system according to claim 41, further comprising a wavefront division optical system arranged in the optical path on the light source side with respect to the conjugate position and which performs wavefront division of the incident light beam and superimposes the divided light beam on a plane including the conjugate position.

44. The illumination optical system according to claim 1, wherein the illumination optical system is used in combination with a projection optical system which forms a plane optically conjugate with the illumination objective surface, the illumination pupil is defined at a position optically conjugate with an aperture stop of the projection optical system.

45. An exposure apparatus comprising the illumination optical system as defined in claim 1 for illuminating a predetermined pattern, the exposure apparatus exposing a photosensitive substrate with the predetermined pattern.

46. The exposure apparatus according to claim 45, further comprising a projection optical system which forms an image of the predetermined pattern on the photosensitive substrate.

47. A device production method comprising the steps of:

exposing the photosensitive substrate with the predetermined pattern by using the exposure apparatus as defined in claim 45;

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

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

55. The polarization unit according to claim 46, wherein at least one of the first optical element and the second optical element has a polarizer which selects a light in a predetermined polarization state from the incident light beam and emits the selected light.

48. A polarization unit which changes a polarization state of a part of an incident light beam having a rectangular cross section and then emits the incident light beam as an outgoing light beam, the polarization unit comprising:

a first optical element which is arranged on a first plane along the cross section of the incident light beam and which changes a polarization state of a second partial light beam in the incident light beam, without exerting any effect on a first partial light beam in the incident light beam; and

a second optical element which is arranged on a second plane along the cross section of the incident light beam and which changes a polarization state of a third partial light beam which is at least a part of the second partial light beam passed through the first optical element, and a polarization state of a fourth partial light beam which is at least a part of the first partial light beam which coming into the second optical element without passing through the first optical element,

wherein the first optical element has a first edge extending in a first direction obliquely intersecting one pair of sides of the rectangular cross section of the incident light beam, and a second edge extending in a second direction different from the first direction.

49. The polarization unit according to claim 48, wherein at least one of the first optical element and the second optical element is configured to be movable along the first plane or the second plane for changing a ratio between a cross-sectional area of the first partial light beam, a cross-sectional area of the second partial light beam, a cross-sectional area of the third partial light beam, and a cross-sectional area of the fourth partial light beam.

50. The polarization unit according to claim 48, wherein the second direction in which the second edge of the first optical element extends is a direction obliquely intersecting the one pair of sides.

51. The polarization unit according to claim 48, wherein the second optical element has a third edge extending in a third direction obliquely intersecting one pair of sides of the rectangular cross section of the incident light beam, and a fourth edge extending in a fourth direction different from the third direction;

and the second optical element is movable two-dimensionally along the second plane.

52. The polarization unit according to claim 48, wherein at least one of the first optical element and the second optical element includes an optical rotation member formed of an optical material having optical rotation property.

53. The polarization unit according to claim 48, wherein at least one of the first optical element and the second optical element includes a wave plate which changes the incident light beam into a light having a predetermined polarization state.

54. The polarization unit according to claim 53, wherein the wave plate is rotatable along the cross section of the incident light beam.