# US 7,746,561 B2 · Projection optical system, exposure apparatus, and method of manufacturing device

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- Number: US 7,746,561 B2
- Document ID: US7746561B2
- Status: Granted
- Kind: B2
- Application number: 12/234,950
- Filed: 2008-09-22
- Published: 2009-03-26
- Granted: 2010-06-29
- Earliest claimed: 2007-09-26
- Assignees: Canon Kabushiki Kaisha
- Inventors: Kazuyoshi Ozawa
- Web page: https://patentgrep.com/patent/US7746561B2

## CPC

- G02B 17/0892: {specially adapted for the UV}
- G02B 13/22: Telecentric objectives or lens systems
- G02B 17/0848: {off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements}
- G03B 27/32: Projection printing apparatus, e.g. enlarger, copying camera
- G03F 7/70225: {Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements}
- G03F 7/7025: {Size or form of projection system aperture, e.g. aperture stops, diaphragms or pupil obscuration; Control thereof}
- G03F 7/70275: {Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

A projection optical system which projects an image of a first object onto a second object includes a plurality of lenses and a plurality of aperture stops for determining a numerical aperture. The plurality of aperture stops include a first aperture stop having an opening whose size can be changed, and a second aperture stop having an opening whose size can be changed. The first and second aperture stops are positioned nearer to the second object than a lens having the maximum effective diameter among the lenses included in an imaging optical system nearest to the second object. At least one of the first and second aperture stops is positioned at or near the pupil of the imaging optical system. The range of the numerical aperture determined by the first aperture stop is larger than the range of the numerical aperture determined by the second aperture stop.

## Claims

### Claim 1

A projection optical system which projects an image of a first object onto a second object, the projection optical system comprising:
a plurality of lenses; and
a plurality of aperture stops for determining a numerical aperture,
wherein said plurality of aperture stops include a first aperture stop having an opening whose size is configured to be changed, and a second aperture stop having an opening whose size is configured to be changed,
wherein said first aperture stop and said second aperture stop are positioned nearer to the second object than a lens having a maximum effective diameter among lenses included in an imaging optical system nearest to the second object,
wherein at least one of said first aperture stop and said second aperture stop is positioned at or near a pupil of the imaging optical system, and
wherein a range of a numerical aperture determined by said first aperture stop is larger than a range of a numerical aperture determined by said second aperture stop.

### Claim 2 (depends on 1)

The projection optical system according to claim 1, wherein NAmin=NAmin1<NAmin2<NAmax1≦NAmax, and NAmin=NAmin1<NAmin2<NAmax2≦NAmax are satisfied when a range of a numerical aperture of said projection optical system is not less than NAmin to not more than NAmax, a range of a numerical aperture determined by said first aperture stop is not less than NAmin1 to not more than NAmax1, and a range of a numerical aperture determined by said second aperture stop is not less than NAmin2 to not more than NAmax2.

### Claim 3 (depends on 2)

The projection optical system according to claim 2, wherein NAmax1=NAmax2=NAmax.

### Claim 4 (depends on 1)

The projection optical system according to claim 1, wherein said second aperture stop is positioned nearer to the second object than said first aperture stop.

### Claim 5 (depends on 1)

The projection optical system according to claim 1, wherein at least one lens included in the imaging optical system is positioned between said first aperture stop and said second aperture stop.

### Claim 6 (depends on 1)

The projection optical system according to claim 1, wherein
said plurality of aperture stops include a third aperture stop, and
NAmin2<NAmin3≦NAmax3=NAmax is satisfied when a range of a numerical aperture determined by said third aperture stop is not less than NAmin3 to not more than NAmax3.

### Claim 7 (depends on 6)

The projection optical system according to claim 6, wherein NAmin3=NAmax3=NAmax is satisfied.

### Claim 8 (depends on 6)

The projection optical system according to claim 6, wherein said third aperture stop is positioned nearer to the second object than said second aperture stop.

### Claim 9 (depends on 6)

The projection optical system according to claim 6, wherein said first aperture stop, said second aperture stop, at least one lens included in the imaging optical system, and said third aperture stop are sequentially positioned from the first object side.

### Claim 10

An exposure apparatus for exposing a substrate to light via an original and a projection optical system,
wherein the projection optical system comprises:
a plurality of lenses; and
a plurality of aperture stops for determining a numerical aperture,
wherein said plurality of aperture stops include a first aperture stop having an opening whose size is configured to be changed, and a second aperture stop having an opening whose size is configured to be changed,
wherein said first aperture stop and said second aperture stop are positioned nearer to the substrate than a lens having a maximum effective diameter among lenses included in an imaging optical system nearest to the substrate,
wherein at least one of said first aperture stop and said second aperture stop is positioned at or near a pupil of the imaging optical system, and
wherein a range of a numerical aperture determined by said first aperture stop is larger than a range of a numerical aperture determined by said second aperture stop.

### Claim 11

A method of manufacturing a device, the method comprising:
exposing a substrate to light by using an exposure apparatus;
developing the exposed substrate; and
processing the developed substrate to manufacture the device,
wherein the exposure apparatus comprises a projection optical system,
wherein the projection optical system comprises:
a plurality of lenses; and
a plurality of aperture stops for determining a numerical aperture,
wherein said plurality of aperture stops include a first aperture stop having an opening whose size is configured to be changed, and a second aperture stop having an opening whose size is configured to be changed,
wherein said first aperture stop and said second aperture stop are positioned nearer to the substrate than a lens having a maximum effective diameter among lenses included in an imaging optical system nearest to the substrate,
wherein at least one of said first aperture stop and said second aperture stop is positioned at or near a pupil of the imaging optical system, and
wherein a range of a numerical aperture determined by said first aperture stop is larger than a range of a numerical aperture determined by said second aperture stop.