Method and device for inspecting spatial light modulator, and exposure method and device

• US 10,317,346 B2
• Filed: 08/30/2012
• Issued: 06/11/2019
• Est. Priority Date: 09/02/2011
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Fujiwara, Tomoharu
• Primary Examiner(s): Kim, Peter B
• Application Number:
  US14/241,951
• Publication Number:
  US 20140320835A1
• Time in Patent Office: 2,476 Days
• Field of Search: 355 67
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01B 11/255 for measuring radius of curvature measuring diameter G01B11/08
• CPC Class Codes: G01M 11/005 Testing of reflective surfaces, e.g. mirrors
• CPC Class Codes: G01N 2021/9511 Optical elements other than lenses, e.g. mirrors testing of optical apparatus in G01M11/00
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 21/95 characterised by the material or shape of the object to be examined G01N21/89 - G01N21/91, G01N21/94 take precedence
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 27/62 Optical apparatus specially adapted for adjusting optical elements during the assembly of optical systems
• CPC Class Codes: G02B 7/003 Alignment of optical elements G02B7/001, G02B7/002 take precedence; for mirrors G02B7/1822
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70425 Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
• CPC Class Codes: G03F 7/7065 Defects, e.g. optical inspection of patterned layer for defects
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/0004 Industrial image inspection

Abstract

A method for inspecting a spatial light modulator includes: performing such control that in an inspection target area in an array of mirror elements, the mirror elements in a first state in which incident light is given a phase change amount of 0 and the mirror elements in a second state in which incident light is given a phase change amount of 180° (π) become arrayed in a checkered pattern; guiding light having passed the inspection target area to a projection optical system with a resolution limit coarser than a width of an image of one mirror element, to form a spatial image; and inspecting a characteristic of the spatial light modulator from the spatial image. This method allows us to readily perform the inspection of the characteristic of the spatial light modulator having the array of optical elements.

Claims

1. An exposure apparatus for exposing an object, comprising:

an illumination system which supplies exposure light;

a spatial light modulator having a base and a plurality of mirrors, each reflecting the exposure light, each of the plurality of mirrors being arranged on the base in parallel with the base;

a projection optical system which projects a pattern onto the object with the exposure light by way of the spatial light modulator;

a base-adjustment system adapted to deform the base, at different positions on the base, in a direction along an optical axis of the projection optical system; and

an inspecting system which inspects information regarding the flatness of the base to be used for the base-adjustment system deforming the base, the inspecting system including a light receiver which receives light from the plurality of mirrors of the spatial light modulator by way of the projection optical system and provides an output regarding the flatness state of the base.

2. The exposure apparatus according to claim 1, wherein the base-adjustment system deforms the base so as to flatten the base.

3. The exposure apparatus according to claim 2, wherein each of the plurality of mirrors of the spatial light modulator is selectively set in one of a first state and a second state, the first state defined as a state in which light from the illumination system is reflected, the second state defined as a state in which the light from the illumination system is reflected so that the light from the illumination system has a phase difference with respect to the light reflected by the first state mirrors, and

the light receiver receives light from the spatial light modulator, the spatial light modulator being set so that the first state mirrors and the second state mirrors are alternately located.

4. The exposure apparatus according to claim 1, wherein the base-adjustment system has a stress applying system which applies a stress to the base.

5. A device manufacturing method comprising:

forming a pattern of a photosensitive layer on a substrate, using the exposure apparatus as set forth in claim 1; and

processing the substrate on which the pattern is formed.

6. An exposure method for exposing an object, comprising:

supplying exposure light;

providing a spatial light modulator having a base and a plurality of mirrors, each reflecting the exposure light, each of the plurality of mirrors being arranged on the base in parallel with the base;

projecting a pattern onto the object with the exposure light, using a projection optical system;

deforming the base, at different positions on the base, in a direction along an optical axis of the projection optical system; and

inspecting information regarding the flatness of the base to be used for the deforming, the inspecting comprising receiving light from the plurality of mirrors of the spatial light modulator by way of the projection optical system and providing an output regarding the flatness state of the base.

7. The exposure method according to claim 6, wherein the deforming flattens the base.

8. The exposure method according to claim 7, wherein each of the plurality of mirrors of the spatial light modulator is selectively set in one of a first state and a second state, the first state defined as a state in which light from an illumination system supplying the exposure light is reflected, the second state defined as a state in which the light from the illumination system is reflected so that the light from the illumination system has a phase difference with respect to the light reflected by the first state mirrors, and wherein

the spatial light modulator is set so that the first state mirrors and the second state mirrors are alternately located.

9. The exposure method according to claim 6, wherein the deforming includes applying a stress to the base.

10. A device manufacturing method comprising:

forming a pattern of a photosensitive layer on a substrate, using the exposure method as set forth in claim 6; and

processing the substrate on which the pattern is formed.