Semiconductor device having a contact plug formed by a dual epitaxial layer and method for fabricating the same

Abstract

During selective epitaxial growth processing using LPCVD equipment, a SiGe epitaxial layer and a Si epitaxial layer are sequentially formed so that lateral overgrowth that could occur in formation of only Si epitaxial layer can be effectively restricted. By adjusting Ge density, SiGe migration is induced at selective epitaxial growth temperatures for forming the conventional Si epitaxial layer. And, by utilizing the internal stress of SiGe and lattice mismatch between the SiGe epitaxial layer and the Si epitaxial layer, the lateral overgrowth is restricted. Furthermore, by hydrogen thermal processing, surface topology of the epitaxial layer is improved.

Dependencies are inferred from the claim text.