Selective epitaxy process with alternating gas supply

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;
• maintaining the process chamber heated to a temperature in a range from about 500° C. to about 750° C.;
• exposing the substrate to a deposition gas to deposit an epitaxial layer on the monocrystalline surface and a polycrystalline layer on the second surface, wherein the deposition gas comprises a silicon source and an inert carrier gas;
• and subsequently
• exposing the substrate to an etching gas to etch the polycrystalline layer at a faster rate than the epitaxial layer, wherein the etching gas comprises an etchant and the inert carrier gas.

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 first deposition gas to deposit a first epitaxial layer on the monocrystalline surface and a polycrystalline surface on the second surface, wherein the deposition gas comprises a silicon source and a dopant compound;
• and subsequently
• exposing the substrate to an etching gas to etch the polycrystalline layer at a faster rate than the epitaxial layer.