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 8,446,579 B2
• Filed: 03/12/2012
• Issued: 05/21/2013
• 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:
  US13/417,602
• Publication Number:
  US 20120171627A1
• Time in Patent Office: 435 Days
• Field of Search: None
• 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

An inspection device is for inspecting a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually. The inspection device includes a Fourier transform optical system which is arranged optically downstream the spatial light modulator and which forms a Fourier transform plane optically in a Fourier transform relation with an array plane where the plurality of optical elements are arrayed, a photodetector having a detection surface arranged on or near the Fourier transform 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 Fourier transform optical system which is arranged optically downstream the spatial light modulator and which forms a Fourier transform plane optically in a Fourier transform relation with an array plane where the plurality of optical elements are arrayed;

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

an inspection unit which inspects optical characteristics of the plurality of optical elements, based on a result of detection by the photodetector.

2. The inspection device according to claim 1, wherein the plurality of optical elements are a plurality of mirror elements.

3. The inspection device according to claim 2, wherein the inspection unit inspects a change characteristic of a posture of at least one mirror element of the plurality of mirror elements based on a light intensity distribution formed on the 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 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 the at least one mirror element of the plurality of mirror elements is changed from the first state.

4. 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, based on a light intensity distribution formed on a Fourier transform plane optically in a Fourier transform relation with an array plane where the plurality of optical elements are arrayed, by light having traveled via the plurality of optical elements.

5. The inspecting method according to claim 4, wherein the plurality of optical elements are a plurality of mirror elements.

6. The inspecting method according to claim 5, comprising inspecting a change characteristic of a posture of at least one mirror element of the plurality of mirror elements based on a light intensity distribution formed on 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 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 the at least one mirror element of the plurality of mirror elements is changed from the first state.

7. An illumination method comprising:

imparting light from a light source to a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually;

forming a predetermined light intensity distribution on an illumination pupil of an illumination optical system, with the light that has travelled via the spatial light modulator;

illuminating an illumination target surface with the light that has travelled via the illumination optical system; and

inspecting the spatial light modulator using the inspecting method as set forth claim 4.

8. An illumination optical system comprising:

a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually, the illumination optical system illuminating an illumination target surface with light from a light source;

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

an inspection device, the inspection device comprising;

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

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

an inspection unit which inspects optical characteristics of the plurality of optical elements, based on a result of detection by the photodetector.

9. The illumination optical system according to claim 8, wherein the distribution forming optical system comprises:

an optical integrator; and

a condensing optical system arranged in an optical path between the optical integrator and the spatial light modulator.

10. The illumination optical system according to claim 8, 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.

11. An exposure apparatus comprising the illumination optical system as set forth in claim 8 for illuminating a predetermined pattern, wherein the predetermined pattern is transferred onto a photosensitive substrate to effect exposure thereof.

12. 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 11;

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.

13. The illumination optical system according to claim 8, wherein the plurality of optical elements are a plurality of mirror elements.

14. The illumination optical system according to claim 13, wherein the inspection unit inspects a change characteristic of a posture of at least one mirror element of the plurality of mirror elements, based on a light intensity distribution formed on the 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 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 the at least one mirror element of the plurality of mirror elements is changed from the first state.

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

a spatial light modulator having a plurality of optical elements arrayed two-dimensionally and controlled individually;

a distribution forming optical system which comprises a condensing optical system and an optical integrator and which forms a predetermined light intensity distribution on an illumination pupil of the illumination optical system, with the light that has travelled via the spatial light modulator;

a splitting optical member which is arranged in an optical path between the spatial light modulator and the distribution forming optical system and which splits part of the light that has traveled via the spatial light modulator;

a Fourier transform optical system which is arranged in an optical path of the light split by the splitting optical member and which forms a Fourier transform plane of a plane where the plurality of optical elements are arrayed;

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

an inspection unit which inspects optical characteristics of the plurality of optical elements, based on a result of detection by the photodetector.

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

a front focal position of the condensing optical system is arranged on or near the plane where the plurality of optical elements are arrayed, and

a rear focal position of the condensing optical system is arranged on or near an entrance-side surface of the optical integrator.

17. The illumination optical system according to claim 16, wherein the plurality of optical elements are a plurality of mirror elements.

18. An exposure apparatus which exposures a photosensitive substrate, the exposure apparatus comprising:

the illumination optical system as set forth claim 15; and

a projection optical system which projects the light from the illumination optical system onto the photosensitive substrate,

wherein the illumination pupil of the illumination optical system is optically conjugate with an aperture stop of the projection optical system.