Si and SiGe faceting during selective epitaxy

Facet apparition during selective epitaxial growth of silicon and silicon–germanium alloys is reported in terms of morphology and kinetics. Epitaxial growth was performed on (0 0 1) Si wafers by chemical vapour deposition using the H2/HCl/SiH2Cl2 chemistry for silicon and GeH4 addition for silicon–germanium alloy. The (0 0 1) Si and SiGe growth rate was found to be limited by chlorine desorption at low temperature. The creation and development of (3 1 1) facets has been clearly explained by the epitaxial growth kinetics considerations. The impact of the deposition conditions, of the pattern structure and also of the dielectric nature on faceting are discussed here and analysed, thanks to cross section scanning electron microscopy (XSEM) and cross section transmission electron microscopy (XTEM) observations.