Method of semiconductor fabrication incorporating disposable spacer into elevated source/drain processing

Abstract

A semiconductor fabrication process includes forming a gate electrode overlying a substrate. A first silicon nitride spacer is formed adjacent the gate electrode sidewalls and a disposable silicon nitride spacer is then formed adjacent the offset spacer. An elevated source/drain structure, defined by the boundaries of the disposable spacer, is then formed epitaxially. The disposable spacer is then removed to expose the substrate proximal to the gate electrode and a shallow implant, such as a halo or extension implant, is introduced into the exposed substrate proximal the gate electrode. A replacement spacer is formed substantially where the disposable spacer existed a source/drain implant is done to introduce a source/drain impurity distribution into the elevated source drain. The gate electrode may include an overlying silicon nitride capping layer and the first silicon nitride spacer may contact the capping layer to surround the polysilicon gate electrode in silicon nitride.