Method and structure for pfet junction profile with sige channel

Abstract

A semiconductor structure including a p-channel field effect transistor (pFET) device located on a surface of a silicon germanium (SiGe) channel is provided in which the junction profile of the source/drain region is abrupt. The abrupt source/drain junctions for pFET devices are provided by forming an N- or C-doped Si layer directly beneath a SiGe channel layer which is located above a Si substrate. A structure is provided in which the N- or C-doped Si layer (sandwiched between the SiGe channel layer and the Si substrate) has approximately the same diffusion rate for a p-type dopant as the overlying SiGe channel layer. Since the N- or C-doped Si layer and the overlying SiGe channel layer have substantially the same diffusivity for a p-type dopant and because the N- or C-doped Si layer retards diffusion of the p-type dopant into the underlying Si substrate, abrupt source/drain junctions can be formed.