REINVESTIGATION OF THE NI SI INTERFACE - SPECTROMICROSCOPIC EVIDENCE FOR MULTIPLE SILICIDE PHASES/

Using photoelectron spectromicroscopy we identified the chemical compo sition of several phases on a morphologically complex interface formed after segregation of dissolved Ni onto the Si(111) surface. Unexpecte dly, coexistence of two types of micrometer-sized silicide islands wit h composition and electronic structure close to NiSi2 and NiSi phases was found. This finding revises some of the previous schemes about the evolution of the Ni/Si(111) system at high temperatures, which were b ased exclusively on structural analyses. A formation mechanism supposi ng anisotropy of the nucleation barrier far disilicide formation is su ggested in order to explain the presence of NiSi islands and the prefe rred [110] orientation of the NiSi2 islands.