Retardation of strain relaxation in Si/SiGe/Si heterostructures during high temperature oxidation

Abstract

The variations of strain stored in Si/Si 1− x Ge x /Si heteroepitaxial system with SiGe thickness below its critical thickness during high temperature oxidation (in O 2–C 2H 2Cl 2 ambient) or annealing (in Ar ambient) processing were investigated by ion channeling angular scan and high resolution X-ray diffraction. The retardation of strain relaxation in an oxidized sample compared with that in an Ar-annealed sample was observed. The depth profiles of Ge determined by SIMS indicated that Ge diffusion in the annealed sample is larger than that in the oxidized sample. The reduced diffusion of Ge in the oxidized sample compared to the Ar-annealed sample is responsible for retardation of strain relaxation.