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Reactive Ion Etching of Aluminum-Copper

IP.com Disclosure Number: IPCOM000037933D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gupta, D: AUTHOR [+5]

Abstract

Aluminum-copper films deposited by sputtering can be selectively removed without accompanying corrosion or residue with reactive ion etching when the films are either subjected to reflow by pulsed laser heating or deposited onto a pure aluminum film prior to the etching step.

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Reactive Ion Etching of Aluminum-Copper

Aluminum-copper films deposited by sputtering can be selectively removed without accompanying corrosion or residue with reactive ion etching when the films are either subjected to reflow by pulsed laser heating or deposited onto a pure aluminum film prior to the etching step.

Aluminum films containing a small portion of copper, such as 4% by weight, exhibit uneven distributions of copper, having the greatest concentrations nearest the substrate, when sputter-deposited at a high rate, substrate temperature or substrate bias voltage. When these films are subjected to pulsed laser melting prior to reactive ion etching using energy concentrations of approximately 2.5 J/cm.2 with 25 nsec. laser pulses, etching is done satisfactorily. The reflow appears to produce a highly uniform metastable phase.

An alternative to reflow is to first sputter deposit a pure aluminum layer beneath the aluminum-copper film. Both films are preferably deposited by using multiple targets and a single pump down. The copper doped layer is deposited under conditions where the single phase region is quickly attained. This causes diffusion of copper into the underlying aluminum and precipitate formation. As long as the period of deposition before reaching the single phase region is short enough, precipitates do not form. If they do form, they are small and at the aluminum-aluminum-copper interface where they can be easily etched. If vacuum must be broken,...