Novel methods for gas phase selective etching of silicon over silicon-germanium layers

Abstract

Methods for selectively etching Si relative to SiGe are provided. The methods utilize a sulfur-containing additive gas in combination with a nitrogen-containing gas and a fluorine-containing gas under certain controlled operating conditions and process sequences. The methods can occur in a cyclic manner including purging after each etch step, until the desired thickness of the Si layer is obtained.

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