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Process for Reactive Ion Etching Composite Films in a Single Reactor

IP.com Disclosure Number: IPCOM000041863D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Bennnett, RS: AUTHOR [+3]

Abstract

Composite films of silicon dioxide/polysilicon/silicon dioxide may be reactive ion etched in a single reactor with one vacuum pumpdown. The details of the reactor apparatus are shown in [*]. Key to this ability to etch composite films is selecting etching gases for SiO2 and Si that are compatible. The two selective etching processes that are combined are (1) CCl2F2 in the diode reactor for etching polysilicon directionally and with selectivity to SiO2 and (2) CClF3 + H2 for etching SiO2 directionally and with selectivity to Si. The etching process for polysilicon is insensitive to trace gases including H2, and the etching process for SiO2 does not form any polymer that would interfere with the etching process for Si. These two processes were used to etch the composite film shown in the figure.

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Process for Reactive Ion Etching Composite Films in a Single Reactor

Composite films of silicon dioxide/polysilicon/silicon dioxide may be reactive ion etched in a single reactor with one vacuum pumpdown. The details of the reactor apparatus are shown in [*]. Key to this ability to etch composite films is selecting etching gases for SiO2 and Si that are compatible. The two selective etching processes that are combined are (1) CCl2F2 in the diode reactor for etching polysilicon directionally and with selectivity to SiO2 and (2) CClF3 + H2 for etching SiO2 directionally and with selectivity to Si. The etching process for polysilicon is insensitive to trace gases including H2, and the etching process for SiO2 does not form any polymer that would interfere with the etching process for Si. These two processes were used to etch the composite film shown in the figure. The etching conditions are as follows: Polysilicon or Si: Etching gas - 25 mm CCl2F2 Flow Rate - 5 sccm RF power - 140 watts top electrode, 60 watts bottom electrode SiO2: Etching gas - 22 mm CClF3 + 67% H2 Flow Rate - 135 sccm RF power - 250 watts bottom electrode The composite film was etched in the diode reactor after one initial pumpdown. Laser end-point detection was used to monitor the etching. When the first silicon dioxide/polysilicon interface was reached, a 20% overetch was carried out, the RF power was turned off, the CClF3 + H2 was pumped out to about 10-5 torr, and CCl2F2 was introduced. When...