| 摘要 |
A silicon germanium alloy layer is formed on a semiconductor material layer by epitaxy. An oxygen impermeable layer is formed on the silicon germanium alloy layer. The oxygen impermeable layer and the silicon germanium alloy layer are patterned to form stacks of a silicon germanium alloy fin and an oxygen impermeable cap. A shallow trench isolation structure is formed by deposition, planarization, and recessing or an oxygen permeable dielectric material. An oxygen impermeable spacer is formed around each stack of a silicon germanium alloy fin and an oxygen impermeable cap. A thermal oxidation process is performed to convert a lower portion of each silicon germanium alloy fin into a silicon germanium oxide. During the thermal oxidation process, germanium atoms diffuse into unoxidized portions of the silicon germanium alloy fins to increase the germanium concentration therein. |
