Semiconductor Device and Method

A method comprising:

• providing a substrate comprising silicon;
• growing a semiconductor layer on the substrate, the semiconductor layer comprising silicon germanium;
• etching trenches in the semiconductor layer and the substrate to form a fin from portions of the semiconductor layer and substrate between the trenches;
• oxidizing the fin to form an oxide layer along sides of the fin, a germanium concentration of the fin at the sides of the fin being increased after oxidation;
• removing the oxide layer from the sides of the fin;
• and
• forming a metal gate stack along a top surface and the sides of the fin.

A method comprising:

• growing a semiconductor layer on a substrate, the substrate comprising silicon, the semiconductor layer comprising silicon germanium, the semiconductor layer having a uniform germanium concentration after the growing;
• etching a trench in the semiconductor layer and the substrate;
• oxidizing sidewalls of the semiconductor layer and the substrate exposed by the trench to form an oxide layer in the trench, the semiconductor layer having a non-uniform germanium concentration after the oxidizing, the germanium concentration at sidewalls of the semiconductor layer after the oxidizing being greater than the germanium concentration at sidewalls of the semiconductor layer before the oxidizing;
• removing the oxide layer;
• and
• depositing an insulation material in the trench.