Method to maximize nitrogen concentration at the top surface of gate dielectrics

摘要

An integrated circuit having a gate dielectric layer (414, 614, 814) having an improved nitrogen profile and a method of fabrication. The gate dielectric layer is a graded layer with a significantly higher nitrogen concentration at the electrode surface than near the substrate surface. An amorphous silicon layer (406) may be deposited prior to nitridation to retain the nitrogen concentration at the top surface (416). Alternatively, a thin silicon nitride layer (610) may be deposited after anneal or a wet nitridation process may be performed.