EFFECTS OF SIH4, GEH4, AND B2H6 ON THE NUCLEATION AND DEPOSITION OF POLYCRYSTALLINE SI1-XGEX FILMS

Abstract

In this study, the effects of different reactants, namely, SiH4, GeH4 and B2H6, on the nucleation and deposition of polycrystalline silicon-germanium (poly-Si1-xGe(x)) films on oxide surface in an ultrahigh vacuum chemical vapor deposition reactor were explored. The results show that the addition of GeH4 tends to retard the nucleation process of poly films while B2H6 is preferential for adsorbing on the oxide surface. These effects lead to different incubation duration depending on the kind of reactants used. On the deposition of poly-Si1-xGe(x) films, it is observed that the Ge incorporation is only slightly related to the substrate type, but the deposition mode of poly-Si1-xGe(x) films is much different from that of epitaxial growth on Si(100). The incorporation of Ge atoms also overcomes the anomalous doping effect encountered in heavily boron-doped poly-Si films and allows extremely low resistivity (below 2 mOMEGA-cm) poly films to be obtained at low temperatures (less-than-or-equal-to550-degrees-C).