Fabrication of devices having different interfacial oxide thickness via lateral oxidation

1. A semiconductor device, comprising:

a first field effect transistor (FET) and a second FET located on a substrate, the first FET comprising a first interfacial oxide layer, and the second FET comprising a second interfacial oxide layer, wherein the second interfacial oxide layer of the second FET is thicker than the first interfacial oxide layer of the first FET and wherein a bottom surface of the second interfacial oxide layer non-planar with a bottom surface of the first interfacial oxide layer; and

a recess located in the substrate directly adjacent to a gate stack of the second FET.

2. The semiconductor device of claim 1 , wherein the first and second interfacial oxide layers comprise one of silicon oxide and silicon oxynitride.

3. The semiconductor device of claim 1 , wherein the substrate comprises one of silicon and silicon germanium.

4. The semiconductor device of claim 1 , wherein the first FET comprises the first interfacial oxide layer located on the substrate, a first high-k dielectric layer located on the first interfacial oxide layer, and a first gate metal layer located on the first high-k dielectric layer; and

wherein the second FET comprises the second interfacial oxide layer located on the substrate, a second high-k dielectric layer located on the second interfacial oxide layer, and a second gate metal layer located on the second high-k dielectric layer.

5. The semiconductor device of claim 1 , further comprising an oxide liner located over a gate of the second FET, and oxidation-resistant material located over the oxide liner.

6. The semiconductor device of claim 1 , further comprising an oxidation-resistant material encapsulating the first FET.