Si and GexSi1−x Epitaxial Growth on SOI Structures by Rapid Thermal Processing Chemical Vapor Deposition

Abstract

AbstractA short time high temperature H2 pre-bake resulted in an undulating SIMOX surface, which planarized after epitaxial growth by rapid thermal processing chemical vapor deposition (RTPCVD). However, a short time, high temperature N2 pre-bake resulted in severe surface pitting. From dilute Schimmel etch results, no significant changes in the defect densities of the Si layers occurred after RTPCVD. Auger depth profiles of the SOI substrate prior to epitaxial growth show an oxygen peak in the SIMOX Si layer. However, the peak flattens out after epitaxial growth. Oxygen was not observed in the epitaxial film, even though oxygen was still observed in the SIMOX top Si layer.The use of GexSi1−x epitaxial layers to reduce threading dislocation densities was examined. A 1000°C Si buffer layer was first grown for 30s, followed by a GexSi1−x layer, and topped off by a 1000°C Si layer for 120s. The GexSi1−x layers were grown at temperatures varying from 850°C to 1000°C for 30s to 240s. The defect density was significantly reduced when the 900°C and 850°C GexSi1−x layers were used, although an increase in stacking fault densities (still small compared to threading dislocation densities) accompanied the lower deposition temperatures. The 1000°C GexSi1−x layer and a control sample in which pure Si was grown showed no significant decrease in defect densities.