Method of selective etching on epitaxial film on source/drain area of transistor

A method, comprising:

• placing a substrate having a plurality of epitaxial features into a processing chamber, wherein each epitaxial feature of the plurality of epitaxial features has at least a surface having a (110) plane and a surface having a (100) plane;
• heating the substrate to a temperature ranging from about 350 degrees Celsius to about 950 degrees Celsius;
• introducing a gas mixture and a carrier gas into the processing chamber, wherein the gas mixture includes an etchant and an etch enhancer or an etch suppressor;
• and
• selectively removing a portion of the epitaxial feature, wherein an etch selectivity between the surface having the (110) plane and the surface having the (100) plane is adjusted by varying a pressure within the processing chamber, a ratio of a flow rate of the gas mixture to a flow rate of the carrier gas, and/or a ratio of a flow rate of the etch enhancer or suppressor to a flow rate of the etchant.

A method, comprising:

• placing a substrate having a plurality of epitaxial features into a processing chamber, wherein each epitaxial feature of the plurality of epitaxial features has at least a surface having a (110) plane and a surface having a (100) plane;
• heating the substrate to a temperature of about 600 degrees Celsius or higher;
• introducing an etchant, a silicon containing gas, and a carrier gas into the processing chamber;
• and
• selectively remove a lateral portion of the epitaxial feature, wherein a height of the epitaxial feature is substantially unchanged.