Silicon germanium alloy fins with reduced defects

摘要

A silicon germanium alloy is formed on sidewall surfaces of a silicon fin. An oxidation process or a thermal anneal is employed to convert a portion of the silicon fin into a silicon germanium alloy fin. In some embodiments, the silicon germanium alloy fin has a wide upper portion and a narrower lower portion. In such an embodiment, the wide upper portion has a greater germanium content than the narrower lower portion. In other embodiments, the silicon germanium alloy fin has a narrow upper portion and a wider lower portion. In this embodiment, the narrow upper portion of the silicon germanium alloy fin has a greater germanium content than the wider lower portion of the silicon germanium alloy fin.

主权项

1. A method of forming a semiconductor structure, said method comprising:
forming a silicon germanium alloy portion on each sidewall surface of a silicon fin, said silicon fin extending upward from a remaining portion of a silicon substrate, wherein said forming said silicon germanium alloy portion comprises;
epitaxially growing a silicon germanium alloy layer on exposed surfaces of said silicon fin;forming a sacrificial dielectric structure having a topmost surface that is located beneath a topmost surface of said silicon fin;forming a sacrificial spacer on a sidewall surface of said silicon germanium alloy layer not protected by said sacrificial dielectric structure;removing said sacrificial dielectric structure;removing portions of said silicon germanium alloy layer not protected by said sacrificial spacer to provide each silicon germanium alloy portion; andremoving said sacrificial spacer; providing a trench isolation dielectric material on exposed surfaces of said remaining portion of said silicon substrate and on exposed sidewall surfaces of each silicon germanium alloy portion and said silicon fin; and converting a portion of the silicon fin that is located laterally adjacent each silicon germanium alloy portion into a silicon germanium alloy fin, wherein said silicon germanium alloy fin comprises a wide upper portion and a narrower lower portion, wherein said silicon germanium alloy fin has a vertically graded germanium content in which said wide upper portion of said silicon germanium alloy fin has a greater germanium content than said narrower lower portion of said silicon germanium alloy fin and wherein sidewall surfaces of said narrower lower portion of said silicon germanium alloy fin are vertically coincident with sidewall surfaces of said silicon fin portion.