A hydrogen pre-bake process for Si epitaxy on sige surface

H 2 pre-bake on SiGe produces a rough surface when the surface oxygen is fully removed. Residue oxygen on SiGe surface prevents surface roughening, but leads to a high density of stacking fault defects in the Si film grown on the surface. A H 2 pre-bake in a chlorine containing environment is developed to remove all the surface oxygen without making the surface rough. Si grown on SiGe with this new pre-bake process shows a defect density reduction of more than four orders of magnitude. An optimized pre-bake process includes a mixture of dichlorosilane (DCS) and HCl in the H 2 gases, with the ratio of DCS and HCl chosen to have near zero growth rate of Si.