Method of making semiconductor device having first and second epitaxial materials

A method of manufacturing a semiconductor device, the method comprising:

• forming a first gate stack over a substrate;
• etching the substrate to define a cavity;
• growing a first epitaxial (epi) material in the cavity, wherein the first epi material includes a first upper surface having a (111) crystal plane;
• growing a second epi material on the first epi material, wherein the second epi material includes a second upper surface having the (111) crystal plane;
• and
• treating the second epi material, wherein treating the second epi material comprises causing the second upper surface to transform to (311) crystal plane.

A method of manufacturing a semiconductor device, the method comprising:

• forming a first gate stack over a substrate;
• etching the substrate to define a cavity;
• growing a first epitaxial (epi) material in the cavity, wherein the first epi material includes a first upper surface having a (111) crystal plane;
• and
• treating the first epi material, wherein treating the first epi material comprises causing the first upper surface to transform to a (311) crystal plane.