Abrupt SiGe and Si Profile Fabrication by Introducing C Delta Layer

摘要

High quality and steep Si/Si_(0.5)Ge_(0.5)/Si profile is fabricated by introducing a C delta layer at the interface using reduced pressure chemical vapor deposition system. The Si_(0.5)Ge_(0.5) and Si layers are deposited by H_2-SiH_4-GeH_4 at 500°C and H_2-Si_2H_6 at 500°C to 575°C, respectively. By introducing a C delta layer at the surface, roughening of the Si_(0.5)Ge_(0.5) surface is maintained at 575°C due to suppressed surface migration of Si and Ge as well as defect injection into the Si_(0.5)Ge_(0.5) layer resulting in high crystallinity Si cap layer growth. Adsorbed CH_3 species at the surface are preventing the epitaxial Si cap layer growth at 500°C, but it is possible to deposit high quality epitaxial Si at higher temperature because of hydrogen-desorption from adsorbed CH_3. Interdiffusion of Si and Ge at the interface is observed at 525°C in the case of sample without C delta layers, but the interdiffusion is suppressed even at 575°C by introducing C delta layers.