Abstract: The silicon/germanium （Si/Ge） inter-diffusion at Si/Si Ge interface in Si/Si Ge/Si heterostructure during thermal processing has been investigated by high-resolution X-ray diffraction （HRXRD）and Raman spectroscopy. Increasing thermal budget i MPairs Si/Si Ge interface more before strain relaxation and a gradient Boron （B） profile at Si/Si Ge holds back inter-diffusion at Si/Si Ge hetero-interface.Raman spectroscopy was used to eliminate the strain relaxation effect,which attributes these results solely to annealing-induced intermixing at the Si/Si Ge interface. In conclusion,the greater Si/Ge inter-diffusion following with increasing thermal budget will induce worse interfacial roughness and deteriorate device performance.