MOS devices having epitaxy regions with reduced facets

摘要

An integrated circuit structure includes a gate stack over a semiconductor substrate, and an opening extending into the semiconductor substrate, wherein the opening is adjacent to the gate stack. A first silicon germanium region is disposed in the opening, wherein the first silicon germanium region has a first germanium percentage. A second silicon germanium region is over the first silicon germanium region. The second silicon germanium region comprises a portion in the opening. The second silicon germanium region has a second germanium percentage greater than the first germanium percentage. A silicon cap substantially free from germanium is over the second silicon germanium region.

主权项

1. An integrated circuit structure comprising:
a semiconductor substrate; a gate stack over the semiconductor substrate; an opening extending into the semiconductor substrate, wherein the opening is adjacent to the gate stack; a first silicon germanium region in the opening, wherein the first silicon germanium region has a first germanium percentage; a second silicon germanium region over the first silicon germanium region, wherein the second silicon germanium region extends at least partially into the opening, wherein the second silicon germanium region comprises:
an upper portion having a second germanium percentage greater than the first germanium percentage; anda lower portion having a third germanium percentage lower than the second germanium percentage, wherein the third germanium percentage is greater than the first germanium percentage; a silicon cap substantially free from germanium over the second silicon germanium region; and a silicide region extending into the silicon cap, wherein the silicide region comprises a higher a germanium percentage than the silicon cap.