Patent ID: 7572715

Claim:
A method of epitaxially forming a silicon-containing material on a substrate surface, comprising: positioning into a process chamber a substrate comprising a monocrystalline surface and at least a second surface selected from the group consisting of an amorphous surface, a polycrystalline surface, and combinations thereof; exposing the substrate to a deposition gas comprising a silicon source and a second elemental source selected from the group consisting of a germanium source, a carbon source, and combinations thereof to deposit an epitaxial layer on the monocrystalline surface and a polycrystalline layer on the second surface; and subsequently exposing the substrate to an etching gas comprising at least a chlorine containing compound to etch the polycrystalline layer at a faster rate than the epitaxial layer, wherein the epitaxial layer has a graded concentration of a second element deposited, at least in part, by the second elemental source.