# US 4,505,782 A · Plasma reactive ion etching of aluminum and aluminum alloys

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- Number: US 4,505,782 A
- Document ID: US4505782A
- Status: Granted
- Kind: A
- Application number: 06/535,929
- Filed: 1983-09-26
- Granted: 1985-03-19
- Earliest claimed: 1983-03-25
- Assignees: LFE Corporation
- Inventors: Adir Jacob; Daniel H. Choe
- Web page: https://patentgrep.com/patent/US4505782A

## 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

A process for a selective plasma-based reactive ion etching of aluminum and aluminum alloys with silicon and copper, employing gas mixtures having BCl.sub.3 as a major constituent and Cl.sub.2, SiF.sub.4, and O.sub.2 as the minor constituents. The major constituent should constitute 40% to 65% by volume of the mixture.

## Claims

### Claim 1

A process for selective reactive ion etching of thin films of aluminum and aluminum alloys in the presence of an etch mask, within a reaction chamber, comprising the step of:
exposing said aluminum metallization within the chamber to a gas plasma for etching, wherein said gas plasma consists essentially of a quaternary mixture of boron trichloride (BCl.sub.3) as a major constituent and chlorine (Cl.sub.2), silicon tetrafluoride (SiF.sub.4), and oxygen (O.sub.2) as the minor constituents, wherein said BCl.sub.3 constitutes 40 to 65% by volume of the mixture, Cl.sub.2 constitutes 15 to 30% by volume, SiF.sub.4 constitutes 10-25% by volume, and O.sub.2 constitutes 2 to 5% by volume of the mixture.

### Claim 2 (depends on 1)

A process in accordance with claim 1 wherein said gas plasma is at a pressure between 10 and 60 microns Hg.

### Claim 3 (depends on 1)

A process in accordance with claim 1 wherein said etchant gas is at a pressure of between 10 and 60 microns Hg and where RF power is supplied to said gas plasma at a rate between 0.075 and 0.188 watts per centimeter square of power density.

### Claim 4

A composition of matter for selective etching of pure aluminum material consisting essentially of a quaternary mixture of boron trichloride (BCl.sub.3) as a major constituent and chlorine (Cl.sub.2), silicon tetrafluoride (SiF.sub.4), and oxygen (O.sub.2) as the minor constituents, wherein said BCl.sub.3 constitutes 40 to 65% by volume of the mixture, Cl.sub.2 constitutes 15 to 30% by volume, SiF.sub.4 constitutes 10-25% by volume, and O.sub.2 constitutes 2 to 5% by volume of the mixture.

### Claim 5

A process for selective reactive ion etching of thin films of sputtered metal aluminum in the presence of an etch mask, within a reaction chamber, comprising the step of:
exposing said aluminum metallization within the chamber to a gas plasma for etching, wherein said gas plasma consists essentially of a quarternary mixture of boron trichloride (BCl.sub.3) as a major constituent and chlorine (Cl.sub.2), silicon tetrafluoride (SiF.sub.4), and oxygen (O.sub.2) as the minor constituents, wherein said BCl.sub.3 constitutes substantially 61% by volume of the mixture, Cl.sub.2 constitutes substantially 19% by volume, SiF.sub.4 constitutes substantially 17% by volume, and O.sub.2 constitutes substantially 3% by volume of the mixture.

### Claim 6

A process for selective reactive ion etching of thin films of electron beam evaporated aluminum/silicon alloys in the presence of an etch mask, within a reaction chamber, comprising the step of:
exposing said aluminum alloy metallization within the chamber to a gas plasma for etching, wherein said gas plasma consists essentially of a mixture of boron trichloride (BCl.sub.3) as a major constituent and chlorine (Cl.sub.2), silicon tetrafluroide (SiF.sub.4), and oxygen (O.sub.2) as the minor constituents, wherein said BCl.sub.3 contitutes substantially 64% by volume of the mixture, Cl.sub.2 constitutes substantially 17% by volume, SiF.sub.4 constitutes substantially 15% by volume, and O.sub.2 constitutes substantially 4% by volume of the mixture.

### Claim 7

A process for selective reactive ion etching of thin films of a sputtered aluminum/silicon alloy in the presence of an etch mask, within a reaction chamber, comprising the step of:
exposing said aluminum metallization within the chamber to a gas plasma for etching, wherein said gas plasma consists essentially of a mixture of boron trichloride (BCl.sub.3) as a major constituent and chlorine (Cl.sub.2), silicon tetrafluoride (SiF.sub.4), and oxygen (O.sub.2) as the minor constituents, wherein said BCl.sub.3 constitutes substantially 61% by volume of the mixture, Cl.sub.2 constitutes substantially 19% by volume, SiF.sub.4 constitutes substantially 17% by volume, and O.sub.2 constitutes substantially 3% by volume of the mixture.

### Claim 8

A process for selective reactive ion etching of thin films of a sputtered alloy of aluminum/silicon/copper in the presence of an etch mask, within a reaction chamber, comprising the step of:
exposing said aluminum metallization within the chamber to a gas plasma for etching, wherein said gas plasma consists essentially of a mixture of boron trichloride (BCl.sub.3) as a major constituent and chlorine (Cl.sub.2), silicon tetrafluoride (SiF.sub.4), and oxygen (O.sub.2) as the minor constituents, wherein said BCl.sub.3 constitutes substantially 58% by volume of the mixture, Cl.sub.2 constitutes substantially 15% by volume, SiF.sub.4 constitutes substantially 21% by volume, and O.sub.2 constitutes substantially 3% by volume of the mixture.