Recessed polysilicon gate structure for a strained silicon mosfet device

Abstract

A method of forming a channel region for a MOSFET device in a strained silicon layer via employment of adjacent and surrounding silicon-germanium shapes, has been developed. The method features simultaneous formation of recesses in a top portion of a conductive gate structure and in portions of the semiconductor substrate not occupied by the gate structure or by dummy spacers located on the sides of the conductive gate structure. The selectively defined recesses will be used to subsequently accommodate silicon-germanium shapes, with the silicon-germanium shapes located in the recesses in the semiconductor substrate inducing the desired strained channel region. The recessing of the conductive gate structure and of semiconductor substrate portions reduces the risk of silicon-germanium bridging across the surface of sidewall spacers during epitaxial growth of the alloy layer, thus reducing the risk of gate to substrate leakage or shorts.