Patent ID: 8029620

Claim:
A method of forming an epitaxial layer stack on a substrate, the epitaxial layer stack comprising a desired thickness and a target carbon concentration, the method comprising: (a) forming a first silicon layer on the substrate, the first silicon layer comprising carbon-containing silicon; (b) forming a second silicon layer on the first silicon layer, wherein the second silicon layer comprises non-carbon-containing silicon; (c) causing carbon from the first silicon layer to distribute to the second silicon layer; (d) etching the epitaxial layer stack to remove a portion of the second silicon layer; (e) repeating steps (a) through (d) until the etched epitaxial layer stack has the desired thickness; and (f) controlling one or more of: (i) an initial carbon concentration, (ii) a thickness and (iii) a deposition time of the first silicon layers to achieve the target carbon concentration of the etched epitaxial layer stack.