Tuning Strain in Semiconductor Devices

摘要

A Fin Field-Effect Transistor (FinFET) includes a semiconductor layer over a substrate, wherein the semiconductor layer forms a channel of the FinFET. A first silicon germanium oxide layer is over the substrate, wherein the first silicon germanium oxide layer has a first germanium percentage. A second silicon germanium oxide layer is over the first silicon germanium oxide layer. The second silicon germanium oxide layer has a second germanium percentage greater than the first germanium percentage. A gate dielectric is on sidewalls and a top surface of the semiconductor layer. A gate electrode is over the gate dielectric.

主权项

1. A method comprising:
performing a first epitaxy to form a first silicon germanium layer over a substrate; performing a second epitaxy to form a second silicon germanium layer over the first silicon germanium layer; performing a third epitaxy to form a silicon layer substantially free from germanium over the second silicon germanium layer; oxidizing the first silicon germanium layer to form a first silicon germanium oxide layer; forming a gate dielectric on a top surface and sidewalls of the silicon layer, wherein the gate dielectric extends on sidewalls of the first silicon germanium oxide layer; and forming a gate electrode over the gate dielectric.