Impact of in situ carbon doping on implant damage and strain relaxation of epitaxial silicon germanium layer on silicon

Implant damage and strain relaxation in thin epitaxial silicon germanium (SiGe) layers on silicon (Si) (001) and their dependence on in situ carbon (C) doping in epitaxial SiGe are studied. For a 65nm SiGe layer with ∼25% germanium (Ge), conventional implants used for p-metal-oxide semiconductor source/drain, halo, and extension led to significant implant damage and strain relaxation. Two defect bands were observed, one close to the surface and the other at SiGe∕Si interface. In situ C doping (1019–1020∕cm3) was found to eliminate the implant damage close to SiGe∕Si interface area and prevent significant strain relaxation.