# US 8,785,086 B2 · Reflective mask blank, method of manufacturing the same, and reflective mask

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- Number: US 8,785,086 B2
- Document ID: US8785086B2
- Status: Granted
- Kind: B2
- Application number: 13/812,627
- Filed: 2011-07-29
- Published: 2013-05-16
- Granted: 2014-07-22
- Earliest claimed: 2010-07-30
- Assignees: Hoya Corporation
- Applicants: Masahiro Hashimoto; Kazunori Ono; Kenta Tsukagoshi; Tooru Fukui
- Inventors: Masahiro Hashimoto; Kazunori Ono; Kenta Tsukagoshi; Tooru Fukui
- Web page: https://patentgrep.com/patent/US8785086B2

## CPC

- G03F 1/24: Reflection masks; Preparation thereof
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 40/00: Manufacture or treatment of nanostructures
- G03F 1/78: by charged particle beam [CPB], e.g. electron beam patterning of masks
- Y10S 430/143: Electron beam
- 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)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

To solve a problem of reduction in accumulated energy due to backward scattering, leading to degradation in CD linearity, which is caused when a generally used high-contrast resist is used in the manufacture of a reflective mask. A reflective mask blank for manufacturing a reflective mask includes a substrate, a multilayer reflective film which is formed on the substrate and adapted to reflect exposure light, and an absorber film which is formed on the multilayer reflective film and adapted to absorb the exposure light. A resist film for electron beam writing is formed on the absorber film and the contrast value γ of the resist film for electron beam writing is 30 or less.

## Claims

### Claim 1

A reflective mask blank for manufacturing a reflective mask, comprising:
a substrate;
a multilayer reflective film which is formed on the substrate and adapted to reflect exposure light;
an absorber film which is formed on the multilayer reflective film and adapted to absorb the exposure light; and
a resist film for electron beam writing which is formed on the absorber film;
wherein a contrast value γ of the resist film is 30 or less.

### Claim 2 (depends on 1)

The reflective mask blank according to claim 1, wherein the contrast value γ of the resist film is 25 or less.

### Claim 3 (depends on 1)

The reflective mask blank according to claim 1, wherein the reflective mask blank is used in EUV lithography which uses EUV light as exposure light.

### Claim 4 (depends on 1)

The reflective mask blank according to claim 1, wherein the absorber film is made of a material containing tantalum.

### Claim 5 (depends on 1)

The reflective mask blank according to claim 1, wherein the number of layers of the multilayer reflective film is 10 cycles or more.

### Claim 6 (depends on 1)

The reflective mask blank according to claim 1, wherein the resist film is made of a chemically amplified resist.

### Claim 7 (depends on 1)

A reflective mask manufactured by using the mask blank according to claim 1 and patterning the absorber film.

### Claim 8

A reflective mask blank for manufacturing a reflective mask, comprising:
a substrate;
a multilayer reflective film which is formed on the substrate and adapted to reflect exposure light;
an absorber film which is formed on the multilayer reflective film and adapted to absorb the exposure light; and
a resist film for electron beam writing which is formed on the absorber film;
wherein an exposure latitude of the resist film is 0.7 nm/% dose or less.

### Claim 9 (depends on 8)

The reflective mask blank according to claim 8, wherein the contrast value γ of the resist film is 25 or less.

### Claim 10 (depends on 8)

The reflective mask blank according to claim 8, wherein the reflective mask blank is used in EUV lithography which uses EUV light as exposure light.

### Claim 11 (depends on 8)

The reflective mask blank according to claim 8, wherein the absorber film is made of a material containing tantalum.

### Claim 12 (depends on 8)

The reflective mask blank according to claim 8, wherein the number of layers of the multilayer reflective film is 10 cycles or more.

### Claim 13 (depends on 8)

The reflective mask blank according to claim 8, wherein the resist film is made of a chemically amplified resist.

### Claim 14 (depends on 8)

A reflective mask manufactured by using the mask blank according to claim 8 and patterning the absorber film.

### Claim 15

A method of manufacturing a reflective mask, comprising the steps of:
preparing a reflective mask blank for manufacturing a reflective mask, the reflective mask blank comprising a substrate, a multilayer reflective film which is formed on the substrate and adapted to reflect exposure light, and an absorber film which is formed on the multilayer reflective film and adapted to absorb the exposure light, and a resist film for electron beam writing on the absorber film; and
forming a resist pattern by the electron beam writing;
wherein a contrast value γ of the resist film is 30 or less.

### Claim 16 (depends on 15)

The method of manufacturing a reflective mask according to claim 15, wherein the contrast value γ of the resist film is 25 or less.

### Claim 17 (depends on 15)

The method of manufacturing a reflective mask according to claim 15, wherein exposure is carried out at an acceleration voltage of an electron beam being 50 keV or more in the electron beam writing.

### Claim 18

A method of manufacturing a reflective mask, comprising the steps of:
preparing a reflective mask blank for manufacturing a reflective mask, the reflective mask blank comprising a substrate, a multilayer reflective film which is formed on the substrate and adapted to reflect exposure light, and an absorber film which is formed on the multilayer reflective film and adapted to absorb the exposure light, and a resist film for electron beam writing on the absorber film;
and
forming a resist pattern by the electron beam writing;
wherein an exposure latitude of the resist film is 0.7 nm/% dose or less.

### Claim 19 (depends on 18)

The method of manufacturing a reflective mask according to claim 18, wherein the contrast value γ of the resist film is 25 or less.

### Claim 20 (depends on 18)

The method of manufacturing a reflective mask according to claim 18, wherein exposure is carried out at an acceleration voltage of an electron beam being 50 keV or more in the electron beam writing.