Removal of semiconductor growth defects

Abstract

After semiconductor material portions and gate structures are formed on a substrate, a dielectric material layer is deposited on the semiconductor material portions and the gate structures. An anisotropic etch is performed on the dielectric material layer to form gate spacers, while a mask layer protects peripheral portions of the semiconductor material portions and the gate structures to avoid unwanted physical exposure of semiconductor surfaces. A selective epitaxy can be performed to form raised active regions on the semiconductor material portions. Formation of semiconductor growth defects during the selective epitaxy is prevented by the dielectric material layer. Alternately, a selective semiconductor deposition process can be performed after formation of dielectric gate spacers on gate structures overlying semiconductor material portions. Semiconductor growth defects can be removed by an etch while a mask layer protects raised active regions on the semiconductor material portions.