Conformal SiGe selective epitaxial growth for advanced CMOS technology

For advanced CMOS technology, embedded Silicon Germanium (SiGe) alloys with high Ge% in source/drain is necessary to boost PMOSFET device performance through hole mobility enhancement. Both incoming Si surface quality and SiGe seed layer conformality are critical for the subsequent epitaxial growth of SiGe material with low defect density. In this paper, we reported an in-situ clean method to achieve a pristine Si surface as well as an optimized epitaxial growth process to form conformal SiGe seed layer. With these solutions, a high-quality embedded SiGe source/drain is achieved resulting in 97% reduction in defect density and 7% improvement in PMOS device performance.