# US 5,350,488 A · Process for etching high copper content aluminum films

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- Number: US 5,350,488 A
- Document ID: US5350488A
- Status: Granted
- Kind: A
- Application number: 07/988,661
- Filed: 1992-12-10
- Granted: 1994-09-27
- Earliest claimed: 1992-12-10
- Assignees: Applied Materials, Inc.
- Inventors: Elaine A. Webb
- Web page: https://patentgrep.com/patent/US5350488A

## CPC

- C23F 4/00: Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
- H10P 50/267: {using plasmas}
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Aluminum alloys containing high amounts of copper can be etched to eliminate copper residues using boron trichloride and chlorine under etch conditions of low temperature, low pressure, high power and strict control of the amount of nitrogen present.

## Claims

### Claim 1

A method for reactive ion etching of an aluminum alloy containing over about 0.5% of copper on a substrate which comprises etching with a precursor gas including boron trichloride and chlorine at temperatures below about 80.degree. C. while regulating the nitrogen content of the precursor gases to prevent formation of a copper residue on the substrate.

### Claim 2 (depends on 1)

A method according to claim 1 wherein the temperature is maintained at about 60.degree.-65.degree. C. during etching.

### Claim 3 (depends on 1)

A method according to claim 1 wherein said aluminum alloy has a layer selected from the group consisting of TiN, TiW and W thereover or thereunder.

### Claim 4 (depends on 3)

A method according to claim 3 wherein said aluminum alloy has a layer of TiN thereover.

### Claim 5 (depends on 1)

A method according to claim 1 wherein the pressure during etching is maintained at a level of about 10 to about 30 millitorr.

### Claim 6

A method of reactive ion etching an aluminum layer containing about 1% by weight of copper on a substrate using boron trichloride and chlorine as the etch gases at a maximum temperature of about 100.degree. C. comprising regulating the amount of nitrogen carrier gas during etching so that formation of a copper residue on the substrate is avoided.

### Claim 7 (depends on 6)

A method according to claim 6 wherein the aluminum has a layer of TiN thereover.

### Claim 8

A method of reactive ion etching an aluminum layer containing about 2% by weight of copper on a substrate using boron trichloride and chlorine as the etch gases at a maximum temperature of about 100.degree. C. comprising etching by regulating the amount of nitrogen present so that formation of a copper residue on the substrate is avoided.

### Claim 9 (depends on 8)

A method according to claim 8 wherein the aluminum has a layer of TiN thereover.