Auger electron spectroscopy and sputter/Auger analyses of thin films of SiC<i>x</i>

Abstract

Thin SiCx films, fabricated in a two-source sputtering apparatus, are analyzed with Auger electron spectroscopy in combination with inert gas (Ne) sputtering. The compositional depth profiles and local bonding properties of the films are the object of the analysis. Different aspects of the application of Auger electron spectroscopy and sputtering to SiC are critically evaluated. These include the chemical information available from the structure of the Auger spectral lines from C and Si, and the effects of ion bombardment, i.e., preferential sputtering, radiation induced diffusion and segregation, as well as disorder. The samples all contain cubic (polycrystalline) SiC( β-SiC). The films are found to be homogeneous in the bulk, with a thin layer at the surface strongly enriched in carbon. A film with a high percentage of Si was found to be inhomogeneous, and to have a significant amount of SiO2 formed at the surface during storage and handling in a room ambient. The films with higher surface concentrations of carbon clearly showed less tendency to form oxides. Chemical information relating to the local bonding of Si and C is obtained from the Si(L23VV) and C (KVV) Auger spectra. The Si (KLL) Auger spectrum is also included in the discussion. Here a comparison with pure silicon allows assignment of plasmon loss structures, as well as shifts in peak energies.