Etching Effect of Hydrogen Plasma on Electron Cyclotron Resonance-Chemical Vapor Deposition and Its Application to Low Temperature Si Selective Epitaxial Growth

Si etching properties by H2 plasma generated using the ECR technique were investigated. The etch rate increases in the order of (111) < (110) < (100). This phenomenon is explained by the bond formation of the Si atoms and the number of the atomic layer for each orientation. Si epitaxial growth was examined by the ECR plasma CVD technique using a SiH4–H2 gas system. At the substrate temperature of 150°C, although the crystallinity degrades with an increase of the film thickness, we confirmed epitaxial growth. An appropriate etching process with H2 plasma, which enhances rearrangement of the Si atoms, is important for Si epitaxial growth at low temperatures. Si epitaxial films with excellent crystallinity and smooth surface morphology as determined by observation of the Kikuchi-lines were obtained at 450°C. Complete selective epitaxial growth was successfully realized at substrate temperature of 150°C by utilizing the etch rate difference for the crystallinity of deposited films. However, the epitaxial thickness was limited to approximately 40 nm. For the substrate temperatures higher than 150°C, the film polycrystallization on an SiO2 substrate degraded the selectivity.