Abrupt SiGe and Si Profile Fabrication by Introducing C Delta Layer

Abstract

High quality and steep Si / Si0.5Ge0.5 / Si profile is fabricated by introducing a C delta layer at the interface using reduced pressure chemical vapor deposition system. The Si0.5Ge0.5 and Si layers are deposited by H2-SiH4-GeH4 at 500oC and H2-Si2H6 at 500oC to 575oC, respectively. By introducing a C delta layer at the surface, roughening of the Si0.5Ge0.5 surface is maintained at 575oC due to suppressed surface migration of Si and Ge as well as defect injection into the Si0.5Ge0.5 layer resulting in high crystallinity Si cap layer growth. Adsorbed CH3 species at the surface are preventing the epitaxial Si cap layer growth at 500oC, but it is possible to deposit high quality epitaxial Si at higher temperature because of hydrogen-desorption from adsorbed CH3. Interdiffusion of Si and Ge at the interface is observed at 525oC in the case of sample without C delta layers, but the interdiffusion is suppressed even at 575oC by introducing C delta layers.