FinFET structures and methods of forming the same

A method comprising:

• epitaxially growing a first crystalline semiconductor material on a substrate, the first crystalline semiconductor material and a portion of the substrate forming a fin on the substrate, wherein after the epitaxially growing the first crystalline semiconductor material, a damaged material layer is on at least a top surface and sidewalls of the first crystalline semiconductor material;
• oxidizing at least outer surfaces of the damaged material layer to form an oxide layer;
• selectively removing the oxide layer;
• repeating the oxidizing and the selectively removing steps while at least a portion of the damaged material layer remains on the first crystalline semiconductor material;
• forming a gate dielectric on at least a top surface and sidewalls of the first crystalline semiconductor material;
• forming a gate electrode on the gate dielectric;
• and
• forming source/drain regions on the fin on opposite sides of the gate electrode.

A method comprising:

• forming a fin extending from a substrate, the fin comprising a first epitaxial portion, the first epitaxial portion comprising a III-V material, a damaged material layer surrounding the first epitaxial portion;
• forming an isolation region over the substrate and surrounding the fin;
• selectively etching a portion of the fin to suspend the first epitaxial portion over the substrate and at a level over a top surface of the isolation region;
• oxidizing the damaged material layer to form an oxide layer;
• selectively removing the oxide layer;
• repeating the oxidizing and the selectively removing steps while at least a portion of the damaged material layer remains on the first epitaxial portion;
• forming a gate dielectric surrounding the first epitaxial portion;
• forming a gate electrode on the gate dielectric;
• and
• forming source/drain regions on opposite ends of the first epitaxial portion.