# US 4,397,938 A · Method of forming resist patterns using X-rays or electron beam

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- Number: US 4,397,938 A
- Document ID: US4397938A
- Status: Granted
- Kind: A
- Application number: 06/330,492
- Filed: 1981-12-14
- Granted: 1983-08-09
- Earliest claimed: 1981-12-14
- Assignees: RCA Corporation
- Inventors: Nitin V. Desai; Emil J. Gavalchin
- Web page: https://patentgrep.com/patent/US4397938A

## CPC

- G03F 7/039: Macromolecular compounds which are photodegradable, e.g. positive electron resists (G03F7/075 takes precedence; macromolecular quinonediazides G03F7/023)
- 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

In accordance with this invention, there is provided a positive resist medium for microlithography which is comprised of a film of a copolymer of sulfur dioxide and certain vinyl esters. A method of manufacturing microelectronic circuits and recording information utilizing the resist medium of this invention is also provided.

## Claims

### Claim 1

A method of forming a patterned layer on a substrate consisting essentially of:
(a) coating the substrate with a composition comprising a solution of a positive acting resist copolymer having a molecular weight of from about 50,000 to about 200,000 and consisting of repeating units represented by the formula ##STR2## wherein R is an alkyl group and n is an integer, in a suitable solvent;
(b) drying the coating to form a positive recording medium;
(c) irradiating a predetermined portion of said medium with an electron beam, a modulated electron beam or x-ray; and
(d) developing the irradiated portion of the medium with a suitable developer.

### Claim 2 (depends on 1)

A method in accordance with claim 1, wherein R is lower alkyl.

### Claim 3 (depends on 2)

A method in accordance with claim 2, wherein R is selected from the group consisting of methyl and tert.-butyl.

### Claim 4 (depends on 3)

A method in accordance with claim 3, wherein R is methyl.

### Claim 5 (depends on 1)

A method in accordance with claim 1, wherein said composition includes from about 10 to about 14 percent by weight of said copolymer.

### Claim 6 (depends on 5)

A method in accordance with claim 5, wherein said solvent is cyclopentanone or 2-methoxyethylacetate.

### Claim 7 (depends on 1)

A method in accordance with claim 1, wherein said medium is irradiated with an electron beam.

### Claim 8 (depends on 1)

A method in accordance with claim 1, wherein said medium is irradiated with a modulated electron beam.

### Claim 9 (depends on 1)

A method in accordance with claim 1, wherein said developer is a combination of cyclopentanone and 3-methylcyclohexanol, 2-methylcyclohexanol or 5-methyl-2-hexanone in a ratio of from about 1:1 to about 3:1.

### Claim 10 (depends on 9)

A method in accordance with claim 9, wherein said developer is a combination of cyclopentanone and 2-methylcyclohexanol in a ratio of 3:1.

### Claim 11 (depends on 1)

A method in accordance with claim 1, wherein said substrate is chromium on glass and development exposes corresponding portions of the substrate.

### Claim 12 (depends on 11)

A method in accordance with claim 11 additionally including etching the exposed substrate with a suitable etchant.