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|1. (WO2017196490) METHOD OF SELECTIVE ETCHING ON EPITAXIAL FILM ON SOURCE/DRAIN AREA OF TRANSISTOR|
|Applicants:||APPLIED MATERIALS, INC.
CHANG, Flora Fong-Song
CHU, Schubert S.
|Title:||METHOD OF SELECTIVE ETCHING ON EPITAXIAL FILM ON SOURCE/DRAIN AREA OF TRANSISTOR|
Methods for forming transistors are provided. A substrate is placed in a processing chamber, and a plurality of epitaxial features is formed on the substrate. The epitaxial feature has at least a surface having the (110) plane and a surface having the (100) plane. An etchant or a gas mixture including an etchant and an etch enhancer or an etch suppressor is introduced into the processing chamber to remove a portion of the epitaxial feature. Etch selectivity between the surface having the (110) plane and the surface having the (100) plane can be tuned by varying the pressure within the processing chamber, the ratio of the flow rate of the etchant or gas mixture to the flow rate of a carrier gas, and/or the ratio of the flow rate of the etch enhancer or suppressor to the flow rate of the etchant.