# US 4,397,939 A · Method of using a positive electron beam resist medium

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- Number: US 4,397,939 A
- Document ID: US4397939A
- Status: Granted
- Kind: A
- Application number: 06/330,579
- Filed: 1981-12-14
- Granted: 1983-08-09
- Earliest claimed: 1981-12-14
- Assignees: RCA Corporation
- Inventors: Kurt B. Kilichowski
- Web page: https://patentgrep.com/patent/US4397939A

## CPC

- C08G 75/22: Copolymers of sulfur dioxide with unsaturated aliphatic compounds
- C08F 218/08: Vinyl acetate
- G03F 7/039: Macromolecular compounds which are photodegradable, e.g. positive electron resists (G03F7/075 takes precedence; macromolecular quinonediazides G03F7/023)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- 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

This invention relates to novel terpolymers of vinyl acetate, 3-methylcyclopentene and sulfur dioxide. Positive electron beam resist media prepared from the subject terpolymers possesses excellent sensitivity and development latitude.

## Claims

### Claim 1

In a method of forming a patterned layer on a substrate comprising:
(a) coating said substrate with a composition comprising a positive acting polymeric resist material and a suitable solvent therefor;
(b) drying said coating to form a positive recording medium;
(c) irradiating selected portions of said medium with an electron beam, a modulated electron beam or x-ray; and
(d) developing the irradiated portions of said medium with a suitable developer, the improvement comprising utilizing as the resist material a terpolymer comprising a monomer component and sulfur dioxide in a 1:1 molar ratio, said monomer component comprising from about 10 mole percent to about 50 mole percent of 3-methylcyclopentene and from about 50 mole percent to about 90 mole percent of vinyl acetate, said terpolymer having a molecular weight of from about 300,000 to about 1,200,000.

### Claim 2 (depends on 1)

A method in accordance with claim 1, wherein the composition contains from about 4 to about 10 percent by weight of said terpolymer.

### Claim 3 (depends on 2)

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

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

A method in accordance with claim 1, wherein said medium is baked prior to irradiation.

### Claim 7 (depends on 1)

A method in accordance with claim 1, wherein said development exposes corresponding portions of the substrate.

### Claim 8 (depends on 7)

A method in accordance with claim 7, additionally including etching the exposed substrate with a suitable etchant.

### Claim 9 (depends on 8)

A method in accordance with claim 8, wherein said substrate is chromium coated on glass.

### Claim 10 (depends on 1)

A method in accordance with claim 1, wherein said developer is a mixture of methylethyl ketone and methylisobutyl ketone.

### Claim 11 (depends on 1)

A method in accordance with claim 1, wherein said developer is a mixture of 2-methylcyclohexanone and 2-methylcyclohexanol.