Amorphization of c‐Si by the sputter deposition of Au studied by x‐ray photoelectron diffraction

Abstract

It is well known that Si atoms can be dislodged from a silicon matrix and diffuse through a thin Au overlayer. In the course of studying this phenomenon, we have found x‐ray photoelectron diffraction (XPD) to be a particularly powerful investigative tool: XPD, a relatively new surface analytical technique, is very sensitive to the surface quality of crystalline materials. We have avoided surface contamination by depositing very thin (<5 nm) Au films onto a (100) Si surface, both by sputtering and by thermal evaporation within the surface instrument. XPD reveals that the c‐Si surface is amorphized by the former process and much less damaged by the latter, a fact we attribute to the higher average kinetic energy of incident Au atoms during sputtering. This interpretation is supported by related studies; for example, by the reaction of adventitious carbon to form Si–C bonds on c‐Si during sputter cleaning and sputter deposition. The study illustrates the important role of even relatively low particle energies and fluxes in ion‐assisted processing.