Publication
Applied Physics Letters
Paper

Silicon loss and transient etch rate in selective reactive ion etching of oxide overlayers

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Abstract

Silicon dioxide to silicon etch selectivity in reactive ion etching (RIE) employing fluorocarbon gases is due to the formation of a fluorocarbon film on the substrate. This implies that etch selectivity is not achieved instantly but that the substrate will exhibit a transient etch rate and hence material loss during the film formation period. The amount of silicon lost during overetching for CF4/H2 RIE was determined by Rutherford backscattering spectrometry employing a buried marker. For standard etching conditions, about 7 nm of silicon is lost within the first minute of overetching as compared to 1.5 nm expected from steady-state etch rate data. The Si etch rate varies strongly as a function of time and decreases by a factor of greater than 10 within the first 30 s of overetching to approach a steady-state value.

Date

01 Dec 1989

Publication

Applied Physics Letters

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