# US 12,181,790 B2 · Reflective mask blank and reflective mask

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- Number: US 12,181,790 B2
- Document ID: US12181790B2
- Status: Granted
- Kind: B2
- Application number: 17/669,986
- Filed: 2022-02-11
- Published: 2022-09-08
- Granted: 2024-12-31
- Earliest claimed: 2021-03-03
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Shin-Etsu Chemical Co., Ltd.
- Inventors: Shohei Mimura; Hideo Kaneko; Tsuneo Terasawa
- Web page: https://patentgrep.com/patent/US12181790B2

## CPC

- G03F 1/24: Reflection masks; Preparation thereof
- G03F 1/54: Absorbers, e.g. of opaque materials
- 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 reflective mask blank that is a material for a reflective mask used in EUV lithography using EUV light as exposure light, including a substrate, a multilayer reflection film that is formed on one main surface of the substrate and reflects the exposure light, and an absorber film containing tungsten, and another metal, a metalloid or a light element that is formed on the multilayer reflection film and absorbs the exposure light.

## Claims

### Claim 1

A reflective mask blank that is a material for a reflective mask used in EUV lithography using EUV light as exposure light, comprising a substrate, a multilayer reflection film that is formed on one main surface of the substrate and reflects the exposure light, and an absorber film that is formed on the multilayer reflection film and absorbs the exposure light, wherein
the absorber film consists of
(a) tungsten; and
(b) at least one element selected from the group consisting of tantalum, molybdenum, vanadium, zirconium, ruthenium, gold, platinum, rhodium, silicon and germanium,
(c) at least one light element selected from the group consisting of nitrogen, oxygen, carbon and hydrogen, or both (b) and (c).

### Claim 2 (depends on 1)

The reflective mask blank of claim 1 wherein the absorber film consists of (a) tungsten, and (b) at least one element selected from the group consisting of tantalum, molybdenum, vanadium, zirconium, ruthenium, gold, platinum, rhodium, silicon and germanium.

### Claim 3 (depends on 1)

The reflective mask blank of claim 1 wherein the absorber film consists of (a) tungsten, (b) at least one element selected from the group consisting of tantalum, molybdenum, vanadium, zirconium, ruthenium, gold, platinum, rhodium, silicon and germanium, and (c) at least one light element selected from the group consisting of nitrogen, oxygen, carbon and hydrogen.

### Claim 4 (depends on 1)

The reflective mask blank of claim 1 wherein the element (b) is either or both of molybdenum and ruthenium.

### Claim 5 (depends on 1)

The reflective mask blank of claim 1 wherein a content of the element (b) in the absorber film is not less than 1 at % and not more than 80 at %.

### Claim 6 (depends on 1)

The reflective mask blank of claim 1 wherein the absorber film consists of (a) tungsten, and (c) at least one light element selected from the group consisting of nitrogen, oxygen, carbon and hydrogen.

### Claim 7 (depends on 6)

The reflective mask blank of claim 6 wherein a content of (c) at least one light element selected from the group consisting of nitrogen, oxygen, carbon and hydrogen is not less than 10 at % and not more than 80 at %.

### Claim 8 (depends on 1)

The reflective mask blank of claim 1 wherein a content of (a) tungsten in the absorber film is not less than 20 at % and not more than 99 at %.

### Claim 9 (depends on 1)

The reflective mask blank of claim 1 wherein the absorber film has a refractive index n of not more than 0.94 with respect to the exposure light.

### Claim 10 (depends on 1)

The reflective mask blank of claim 1 wherein the absorber film has a thickness of not more than 70 nm.

### Claim 11 (depends on 4)

The reflective mask blank of claim 4 comprising a protection film composed of a material containing ruthenium (Ru) wherein the protection film is intervened between the multilayer reflection film and the absorber film, is contact with the multilayer reflection film, and has different etching property from the absorber film.

### Claim 12 (depends on 1)

The reflective mask blank of claim 1 further comprising a conductive film formed on the other main surface of the substrate.

### Claim 13 (depends on 1)

The reflective mask blank of claim 1 further comprising a film containing chromium formed as an etching mask on the absorber film.

### Claim 14 (depends on 1)

A reflective mask manufactured from the reflective mask blank of claim 1.

### Claim 15 (depends on 6)

The reflective mask blank of claim 6 comprising a protection film wherein the protection film is intervened between the multilayer reflection film and the absorber film, is contact with the multilayer reflection film, and has different etching property from the absorber film.