# US 4,400,461 A · Process of making semiconductor devices using photosensitive bodies

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- Number: US 4,400,461 A
- Document ID: US4400461A
- Status: Granted
- Kind: A
- Application number: 06/265,554
- Filed: 1981-05-22
- Granted: 1983-08-23
- Earliest claimed: 1981-05-22
- Assignees: Bell Telephone Laboratories, Incorporated
- Inventors: Edwin A. Chandross; Elsa Reichmanis; Cletus W. Wilkins, Jr.
- Web page: https://patentgrep.com/patent/US4400461A

## CPC

- G03F 7/0045: {with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors}
- 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

Photosensitive bodies that are sensitive to ultraviolet radiation and that exhibit excellent contrast are formed from base soluble polymers such as poly(methyl methacrylate-co-methacrylic acid) physically mixed with base insoluble materials such as o-nitrobenzyl esters. The base insoluble esters decompose upon irradiation to form base soluble entities in the irradiated regions. These irradiated portions are then soluble in basic solutions that are used to develop the desired image.

## Claims

### Claim 1

A process for preparing a semiconductor device comprising the steps of depositing a photosensitive material on a substrate comprising a semiconductor material, irradiating said photosensitive material with electromagnetic radiation in a desired pattern, developing said pattern with an alkaline solution, and completing the fabrication of said semiconductor device wherein said photosensitive material comprises a mixture of an o-nitroarylmethyl ester of a carboxylic acid and a polymer which is soluble in said alkaline solution, said o-nitroarylmethyl ester being represented by the formula ##STR6## where R.sub.1 is a substituent chosen so that a salt of the carboxylic acid, R.sub.1 COOH, is sufficiently soluble in water to produce at least a 0.01 M solution and R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are chosen so that the ratio expressed as 1:n of the solubility rate of said unexposed to said exposed portions is such that n is at least 4.

### Claim 2 (depends on 1)

The process of claim 1 wherein said substrate is a silicon wafer.

### Claim 3 (depends on 1)

The process of claim 1 wherein R.sub.1 corresponds to the R.sub.1 in the carboxylic acid, R.sub.1 COOH and wherein said carboxylic acid is chosen from the group consisting of N-adamantylphthalamic acid, cholic acid, deoxycholic acid, lithocholic acid, 5.beta.-cholanic acid, O,O,O-tris(trimethylsilyl)cholic acid, O,O,O-tris(trifluoroacetyl)cholic acid, O,O,O-triacetylcholic acid, O,O,O-tripivaloylcholic acid, and O,O-diacetylcholic acid.

### Claim 4 (depends on 1)

The process of claim 1 wherein said o-nitroarylmethyl ester is an o-nitrobenzyl ester.

### Claim 5 (depends on 1)

The process of claim 1 wherein said value of n is at least 10.

### Claim 6 (depends on 1)

The process of claim 1 wherein said polymer comprises a copolymer of methyl methacrylate and methacrylic acid.

### Claim 7 (depends on 1)

The process of claim 1 wherein the amount of said o-nitroarylmethyl ester to said polymer is in the range 5 to 40 weight percent.

### Claim 8 (depends on 1)

The process of claim 1 wherein said alkaline solution comprises an aqueous Na.sub.2 CO.sub.3 solution.

### Claim 9 (depends on 1)

The process of claim 1 wherein said alkaline solution comprises an aqueous solution of Na.sub.2 CO.sub.3 and NaHCO.sub.3.

### Claim 10 (depends on 1)

The process of claim 1 wherein said polymer has a molecular weight ranging from about 20,000 to about 200,000.

### Claim 11 (depends on 10)

The process of claim 10 wherein said polymer has a molecular weight ranging from about 30,000 to about 70,000.