Process for Reactive Ion Etching Composite Films in a Single Reactor
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
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.