Illumination optical system, aligner, and process for fabricating device

• US 20110211183A1
• Filed: 02/25/2011
• Published: 09/01/2011
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu
• Granted Patent: US 8,913,227 B2
• Time in Patent Office: Days
• 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

[Problem] Each of pupil intensity distributions at respective points on an illumination target surface is substantially uniformly adjusted.

[Solving Means] An illumination optical system to illuminate an illumination target surface (M; W) on the basis of light from a light source (1) is provided with a distribution forming optical system (3, 4, 5) for forming a pupil intensity distribution on an illumination pupil of the illumination optical system, and a correction unit (12) which is arranged at or near a position of the illumination pupil, or, at or near a position optically conjugate with the illumination pupil, in order to correct the pupil intensity distribution, and which changes an emission direction of a beam according to an incidence position of the beam.

Claims

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

a distribution forming optical system, arranged in an optical path of the illumination optical system, forming a pupil intensity distribution on an illumination pupil of the illumination optical system; and

a correction unit, for correcting the pupil intensity distribution, changing an emission direction of a beam according to an incidence position of the beam, the correction unit being arranged at or near a position of the illumination pupil, or, arranged at or near a position optically conjugate with the illumination pupil.

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

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

8. The illumination optical system according to claim 1, wherein the correction unit 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 unit 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 unit,

wherein the correction unit 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 unit,

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

14. The illumination optical system according to claim 1, wherein the correction unit 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 unit corrects almost all of the light from the pupil intensity distribution.

16. The illumination optical system according to claim 15, 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 unit 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.