Illumination apparatus, illumination method, exposure apparatus, and device manufacturing method

• US 9,678,332 B2
• Filed: 03/20/2015
• Issued: 06/13/2017
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu
• Primary Examiner(s): Kim, Peter B
• Application Number:
  US14/664,576
• Publication Number:
  US 20150212424A1
• Time in Patent Office: 816 Days
• Field of Search: 355 67, 355 71, 359237
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• 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 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70075 Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection
• 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

To optionally forming a multilevel light intensity distribution on an illumination pupil plane, the illumination apparatus implements Köhler illumination on an illumination target surface, using as a light source the light intensity distribution formed on the illumination pupil plane on the basis of light from a light source. The illumination apparatus has a spatial light modulator, a condensing optical system, and a controller. The spatial light modulator has reflecting surfaces which are two-dimensionally arranged and postures of which can be controlled independently of each other. The condensing optical system condenses light from the reflecting surfaces to form a predetermined light intensity distribution on the illumination pupil plane. The controller controls the number of reflecting surfaces contributing to arriving light, for each of points on the illumination pupil plane forming the light intensity distribution, according to a light intensity distribution to be formed on the illumination pupil plane.

Claims

1. An illumination apparatus which illuminates an illumination target surface with light, the illumination apparatus comprising:

a spatial light modulator with a plurality of reflecting surfaces and a driving unit, the plurality of reflecting surfaces being arranged two-dimensionally in an optical path of the light, the driving unit being capable of setting postures of the respective reflecting surfaces independently of each other;

an optical system including a lens element arranged in the optical path of the light on a reflected side of the plurality of reflecting surfaces;

a fly'"'"'s eye optical system arranged in the optical path of the light on an emitting side of the optical system; and

a controller which controls the driving unit of the spatial light modulator to set the postures of first reflecting surfaces among the plurality of reflecting surfaces into a first inclination so that light beams from the first reflecting surfaces overlap on a predetermined surface via the optical system, the predetermined surface being located on or near an entrance surface of the eye optical system.

2. The illumination apparatus according to claim 1, wherein

the controller controls the driving unit to set the postures of second reflecting surfaces among the plurality of reflecting surfaces into a second inclination so that light beams from the second reflecting surfaces overlap on the predetermined surface via the optical system so as not to overlap with the light beams from the first reflecting surfaces on the predetermined surface, the first and second inclinations being different from each other.

3. The illumination apparatus according to claim 1, further comprising:

a condensing optical system arranged in the optical path between the fly'"'"'s eye optical system and the illumination target surface, the condensing optical system being configured to condense light from the fly'"'"'s eye optical system onto the illumination target surface.

4. The illumination apparatus according to claim 3, wherein

the condensing optical system causes a condition that the illumination target surface becomes an optical Fourier transform surface of an illumination pupil plane of the illumination apparatus.

5. The illumination apparatus according to claim 1, wherein

the illumination apparatus is used together with a projection optical system which projects a pattern arranged on the illumination target surface onto an image surface.

6. The illumination apparatus according to claim 1, wherein

the spatial light modulator is arranged near a front focal point of the optical system.

7. The illumination apparatus according to claim 6, wherein

a rear focal point of the optical system is located on the predetermined surface.

8. An exposure apparatus including the illumination apparatus according to claim 1 for illuminating a predetermined pattern, wherein

the exposure apparatus performs exposure of the predetermined pattern on a photosensitive substrate.

9. An illumination method which illuminates an illumination target surface with light, the illumination method comprising:

reflecting the light by a plurality of reflecting surfaces arranged two-dimensionally in an optical path of the light, respective postures of the plurality of reflecting surfaces being set independently of each other by a driving unit;

guiding light reflected by the plurality of reflecting surfaces onto a fly'"'"'s eye optical system arranged in the optical path of the light on an emitting side of an optical system, the optical system including a lens element arranged in the optical path of the light on a reflected side of the plurality of reflecting surfaces, wherein

the reflecting includes controlling the driving unit to set the postures of first reflecting surfaces among the plurality of reflecting surfaces into a first inclination so that light beams from the first reflecting surfaces overlap on a predetermined surface after passing through the optical system, the predetermined surface being located on or near an entrance surface of the fly'"'"'s eye optical system.

10. The illumination method according to claim 9, wherein

the reflecting includes controlling the driving unit to set the postures of second reflecting surfaces among the plurality of reflecting surfaces into a second inclination so that light beams from the second reflecting surfaces overlap on the predetermined surface via the optical system so as not to overlap with the light beams from the first reflecting surfaces on the predetermined surface, the first and second inclinations being different from each other.

11. The illumination method according to claim 9, further comprising:

condensing light from the fly'"'"'s eye optical system onto the illumination target surface.

12. The illumination method according to claim 11, wherein

the condensing includes causing a condition that the illumination target surface becomes an optical Fourier transform surface of an illumination pupil plane.

13. The illumination method according to claim 11, wherein

the illumination method is used for projecting a pattern arranged on the illumination target surface onto an image surface by using a projection optical system.

14. The illumination method according to claim 13, wherein

a surface on which the plurality of reflecting surfaces are two-dimensionally arranged is located near a front focal point of the condensing optical system.

15. The illumination method according to claim 14, wherein

a rear focal point of the condensing optical system is located on the predetermined surface.

16. An exposure method including:

illuminating a predetermined pattern by using the illumination method according to claim 9; and

performing exposure of the predetermined pattern on a photosensitive substrate.

17. A device manufacturing method comprising:

effecting exposure of a predetermined pattern on a photosensitive substrate, using the exposure method according to claim 16;

developing the photosensitive substrate onto which the predetermined pattern has been transferred;

forming 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.