Illumination optical system, exposure apparatus, optical element and manufacturing method thereof, and device manufacturing method

• US 8,451,427 B2
• Filed: 08/14/2008
• Issued: 05/28/2013
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu
• Primary Examiner(s): Nguyen, Hung Henry
• Assistant Examiner(s): KREUTZER, COLIN WRIGHT
• Application Number:
  US12/191,821
• Publication Number:
  US 20090073411A1
• Time in Patent Office: 1,748 Days
• Field of Search: 250/492.2, 250/492.22, 355/53, 355/67, 355/71, 355/77, 359850-851
• US Class Current: 355/67
• CPC Class Codes: G02B 26/00 Optical devices or arrangements for the control of light using movable or deformable optical elements control of light by modification of the optical properties of the media of the elements involved therein G02F1/00
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• 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
• CPC Class Codes: G03F 7/70141 Illumination system adjustment, e.g. adjustments during exposure or alignment during assembly of illumination system
• CPC Class Codes: G03F 7/70158 Diffractive optical elements

Abstract

An illumination optical system which illuminates a surface to be illuminated on the basis of light from a light source has a first optical path in which a diffractive optical element can be arranged at a first position thereof; a second optical path in which a spatial light modulator with a plurality of optical elements arrayed two-dimensionally and controlled individually can be arranged at a second position thereof; and a third optical path which is an optical path of light having passed via at least one of the first optical path and the second optical path and in which a distribution forming optical system is arranged. The distribution forming optical system forms a predetermined light intensity distribution on an illumination pupil located in the third optical path, based on the light having passed via at least one of the first and second optical paths.

Claims

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

a diffractive optical element which can be inserted at and retracted from a first position in an optical path of the illumination optical system by operation of a control system;

a spatial light modulator with a plurality of optical elements arrayed two-dimensionally and controlled individually, which can be inserted at and retracted from the first position or a second position optically conjugate with the first position by operation of the control system; and

a distribution forming optical system which forms a predetermined light intensity distribution on an illumination pupil with light having passed via at least one of the diffractive optical element and the spatial light modulator.

2. The illumination optical system according to claim 1, wherein the spatial light modulator can be replaced with a plane mirror or a prism mirror at the second position.

3. The illumination optical system according to claim 2, comprising a path folding reflecting mirror which is arranged immediately before the spatial light modulator and which sets an angle of incidence of light to the spatial light modulator to not more than a predetermined angle.

4. The illumination optical system according to claim 2, which comprises a polarization beam splitter arranged in an optical path between the light source and the spatial light modulator, and a quarter wave plate arranged in an optical path between the polarization beam splitter and the spatial light modulator, wherein light incident to the polarization beam splitter is guided via the quarter wave plate, the spatial light modulator, the quarter wave plate, and the polarization beam splitter to the target surface.

5. The illumination optical system according to claim 1, comprising a control unit which controls arrangement of at least one of the diffractive optical element and the spatial light modulator in the optical path.

6. The illumination optical system according to claim 5, wherein the control unit arranges either one of the diffractive optical element and the spatial light modulator at the first position.

7. The illumination optical system according to claim 5, wherein the control unit arranges the diffractive optical element at the first position and the spatial light modulator at the second position.

8. The illumination optical system according to claim 1, wherein the spatial light modulator includes a plurality of mirror elements arrayed two-dimensionally, and a driving unit which individually controls and drives postures of the plurality of mirror elements.

9. The illumination optical system according to claim 8, wherein the driving unit continuously or discretely changes orientations of the plurality of mirror elements.

10. The illumination optical system according to claim 1, which is used in combination with a projection optical system which forms a surface optically conjugate with the target surface, wherein the illumination pupil is at 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 1, for illuminating a predetermined pattern, the exposure apparatus performing an exposure of the predetermined pattern on a photosensitive substrate.

12. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus as set forth in claim 11;

developing the photosensitive substrate to which the pattern has been transferred, to form a mask layer in a shape corresponding to the 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 1, wherein the distribution forming optical system has an optical integrator and forms the a predetermined light intensity distribution on an illumination pupil located at or near the target surface side of the optical integrator.