Optical unit, illumination optical apparatus, exposure apparatus, and device manufacturing method

• US 9,057,877 B2
• Filed: 04/17/2012
• Issued: 06/16/2015
• Est. Priority Date: 10/24/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu
• Primary Examiner(s): NGUYEN, HUNG
• Application Number:
  US13/449,115
• Publication Number:
  US 20120202157A1
• Time in Patent Office: 1,155 Days
• Field of Search: 355/52, 355/53, 355/55, 355/67, 355/71
• US Class Current: 1/1
• CPC Class Codes: F21V 13/02 Combinations of only two kinds of elements
• CPC Class Codes: F21V 14/003 by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices
• CPC Class Codes: F21V 9/14 for producing polarised light
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0938 Using specific optical elements
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• 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 7/70566 Polarisation control

Abstract

An illumination optical apparatus has an optical unit. The optical unit has a light splitter to split an incident beam into two beams; a first spatial light modulator which can be arranged in an optical path of a first beam; a second spatial light modulator which can be arranged in an optical path of a second beam; and a light combiner which combines a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator; each of the first spatial light modulator and the second spatial light modulator has a plurality of optical elements arranged two-dimensionally and controlled individually.

Claims

1. An optical unit comprising:

a light splitter, arranged in a path of an incident beam, to split the incident beam into a plurality of beams;

a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams;

a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams; and

a light combiner, arranged in a path of a beam having passed via the first spatial light modulator and a path of a beam having passed via the second spatial light modulator, to combine the beam having passed via the first spatial light modulator, with the beam having passed via the second spatial light modulator;

wherein at least one spatial light modulator out of the first spatial light modulator and the second spatial light modulator includes a plurality of optical elements arranged two-dimensionally and controlled individually;

wherein the incident beam has such a sectional shape that a length along a first direction in a cross section of the incident beam is smaller than a length along a second direction perpendicular to the first direction, and

wherein the light splitter splits the incident beam along the first direction.

2. The optical unit according to claim 1, said optical unit being used in an illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the optical unit guiding light to a distribution forming optical system in the illumination optical apparatus in order to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus.

3. An illumination optical apparatus to illuminate an illumination target surface on the basis of light from a light source, the illumination optical apparatus comprising:

the optical unit as set forth in claim 1; and

a distribution forming optical system to form a predetermined light intensity distribution on an illumination pupil of the illumination optical apparatus, based on the beams having passed via the first and second spatial light modulators.

4. An exposure apparatus comprising the illumination optical apparatus as set forth in claim 3, for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

5. 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 4;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, 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.