Highly strain-relaxed ultrathin SiGe-on-insulator structure by Ge condensation process combined with H~+ irradiation and postannealing

摘要

Strain-relaxation process of SiGe-on-insulator (SGOI) structures in the oxidation induced Ge condensation method has been investigated as a function of the SiGe thickness. Complete relaxation was obtained for thick SGOI layers ( > 100 nm). However, the relaxation rates abruptly decreased with decreasing SiGe thickness below 50 nm, i.e., the relaxation rate of 30% at 30 nm SiGe thickness. In order to improve this phenomenon, a method combined with H~+ irradiation with a medium dose (5 X 10~(15) cm~(-2)) and postannealing (1200℃) has been developed. This successfully achieved the high relaxation rate (70%) in the ultrathin SGOI (30 nm).