Recessed and Epitaxially Regrown SiGe(B) Source/Drain Junctions with Ni salicide contacts

Abstract

ABSTRACTIntegration issues concerning recessed epitaxial SiGe(B) source/drain junctions formed by selective Si etching followed by selective epitaxial growth of in situ heavily B-doped Si1−xGex are presented. The concept is beneficial compared to conventional ion implanted junctions, since dopant activation above the solid solubility in Si can be obtained. When integrated in the PMOS process flow, the resulting Si1−xGex layer is very rough. Several possible causes for low quality epitaxy are discussed and improvements are proposed. It is suggested that the dopant type and/or concentration in the silicon substrate can have an effect on the process.