Illumination optical system, aligner, and process for fabricating device

• US 8,913,227 B2
• Filed: 02/25/2011
• Issued: 12/16/2014
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu
• Primary Examiner(s): Whitesell Gordon, Steven H
• Application Number:
  US12/929,944
• Publication Number:
  US 20110211183A1
• Time in Patent Office: 1,390 Days
• Field of Search: 355/53, 355/67, 355/71, 355/77, 355/68
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70108 Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides
• 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

Abstract

According to one embodiment, an illumination optical system configured to illuminate an illumination target surface on the basis of light from a light source comprises a distribution forming optical system and a correction unit. The distribution forming optical system forms a pupil intensity distribution on an illumination pupil of the illumination optical system. The correction unit changes an emission direction of a beam according to an incidence position of the beam, in order to correct the pupil intensity distribution. The correction unit is arranged at or near a position of the illumination pupil, or, arranged at or near a position optically conjugate with the illumination pupil.

Claims

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

a distribution forming optical system having an optical integrator which has a plurality of optical surfaces, the plurality of optical surfaces being arrayed two-dimensionally on a plane intersecting with an optical path of the illumination optical system, the distribution forming optical system distributing a beam having passed through the optical integrator onto an illumination pupil of the illumination optical system;

a condenser optical system arranged on an optical path of the beam traveling from the optical integrator to the illumination target surface, the condenser optical system superposing a plurality of beams from the plurality of optical surfaces on the illumination target surface; and

a correction member arranged on a section of the optical path of the beam between the illumination pupil and the illumination target surface, the correction member changing an emission direction of the beam according to an incidence position of the beam.

2. The illumination optical system according to claim 1, wherein the correction member actively changes the emission direction of the beam.

3. The illumination optical system according to claim 1, wherein the correction member comprises a spatial light modulator with a plurality of optical elements arrayed two-dimensionally and controlled individually.

4. The illumination optical system according to claim 3, wherein the spatial light modulator has a plurality of mirror elements arrayed two-dimensionally, and a drive unit which individually controls and drives postures of the plurality of mirror elements.

5. The illumination optical system according to claim 4, wherein the drive unit continuously or discretely changes orientations of the plurality of mirror elements.

6. The illumination optical system according to claim 3, wherein the spatial light modulator has a plurality of variable angle prisms arrayed two-dimensionally, and a drive unit which individually controls and drives apex angles of the plurality of variable angle prisms.

7. The illumination optical system according to claim 1, wherein the correction member has a locally deformable reflecting surface.

8. The illumination optical system according to claim 1, wherein the correction member has a locally deformable refracting surface.

9. The illumination optical system according to claim 1, further comprising a light quantity distribution adjusting unit, the light quantity distribution adjusting unit changing an illuminance distribution on the illumination target surface or a shape of an illumination region formed on the illumination target surface.

10. The illumination optical system according to claim 9, wherein the light quantity distribution adjusting unit corrects influence of the correction member on a light quantity distribution on the illumination target surface.

11. The illumination optical system according to claim 1, used in combination with a projection optical system configured to form 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.

12. The illumination optical system according to claim 1, further comprising a beam splitter arranged upstream of the correction member,

wherein the correction member can receive light via the beam splitter.

13. The illumination optical system according to claim 12, further comprising a beam combiner arranged downstream of the correction member,

wherein the beam combiner can receive light from the correction member and light from the beam splitter.

14. The illumination optical system according to claim 1, wherein the correction member includes a reflecting surface, and

wherein an optical path upstream the reflecting surface and an optical path downstream the reflecting surface are folded.

15. The illumination optical system according to claim 1, wherein the correction member corrects substantially all of the light traveling from the optical integrator to the illumination target surface.

16. The illumination optical system according to claim 15, wherein the correction member includes a reflecting surface, and

wherein an optical path upstream the reflecting surface and an optical path downstream the reflecting surface are folded.

17. An exposure apparatus comprising the illumination optical system as set forth in claim 1 configured to illuminate a predetermined pattern, the exposure apparatus performing exposure to expose a photosensitive substrate to the predetermined pattern.

18. The exposure apparatus according to claim 17, comprising a projection optical system configured to form an image of the predetermined pattern on the photosensitive substrate.

19. The exposure apparatus according to claim 18, further comprising:

a measuring unit, arrangeable downstream the projection optical system, measuring a pupil intensity distribution on a pupil plane of the projection optical system, on the basis of light having traveled via the projection optical system; and

a control unit, connectable to the measuring unit, controlling the correction member on the basis of the result of measurement by the measuring unit, in order to adjust the pupil intensity distribution to a required distribution.

20. A device manufacturing method, comprising:

performing exposure of the photosensitive substrate with the predetermined pattern, using the exposure apparatus as set forth in claim 17;

developing the photosensitive substrate with the predetermined pattern being transferred thereon, 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.

21. The illumination optical system according to claim 1, wherein the correction member is arranged at or near a position of the illumination pupil, or, arranged at or near a position optically conjugate with the illumination pupil.

22. The illumination optical system according to claim 1, further comprising:

a measuring unit which measures a pupil intensity distribution relevant to the beam incident on a predetermined point on the illumination target surface; and

a control unit which controls the correction member on the basis of the result of measurement by the measuring unit, in order to adjust the pupil intensity distribution to a required distribution.

23. The illumination optical system according to claim 22, wherein the measuring unit measures pupil intensity distributions relevant to beams respectively incident on a plurality of points which include the predetermined point and are on the illumination target surface.

24. An illumination optical system which illuminates an illumination target surface with light from a light source, comprising:

a distribution forming optical system having an optical integrator which has a plurality of optical surfaces, the plurality of optical surfaces being arrayed two-dimensionally on a plane intersecting with an optical path of the illumination optical system, the distribution forming optical system distributing a beam having passed through the optical integrator onto an illumination pupil of the illumination optical system;

a condenser optical system arranged on an optical path of the beam traveling from the optical integrator to the illumination target surface, the condenser optical system superposing a plurality of beams from the plurality of optical surfaces on the illumination target surface; and

a correction member arranged on a section of the optical path of the beam traveling between the illumination pupil and the illumination target surface, the correction member having a plurality of optical elements arrayed two-dimensionally and controlled individually.

25. The illumination optical system according to claim 24, wherein the plurality of optical elements actively change emission directions of beams emitted from the plurality of optical elements.

26. The illumination optical system according to claim 25, wherein the correction member unit is arranged at or near a position of the illumination pupil, or, arranged at or near a position optically conjugate with the illumination pupil.

27. The illumination optical system according to claim 24, further comprising:

a measuring unit which measures a pupil intensity distribution relevant to the beam incident on a predetermined point on the illumination target surface; and

a control unit which controls the correction member on the basis of the result of measurement by the measuring unit, in order to adjust the pupil intensity distribution to a required distribution.

28. The illumination optical system according to claim 27, wherein the measuring unit measures pupil intensity distributions relevant to beams respectively incident on a plurality of points which include the predetermined point and are on the illumination target surface.