The Element Depth Profiles in Ultrathin Silicon Oxynitride Films

Distribution of nitrogen in the thin silicon oxynitride films (less than 5 nm) obtained by plasma nitridation of SiO2 has been studied by non-destructive angular dependent XPS. For obtaining information about the element distribution in-depth the regularization technique has been applied. It is shown that the depth of nitrogen penetration increases with decreasing the SiO2 film thickness. In this case the maximum of the nitrogen distribution is enhanced and shifted to the Si-SiO2 interface. The results are compared with depth-profiling obtained by sputtering and wet chemical etching. The dependence of the binding energies on the film thickness has been studied. The influence of different factors on the chemical shift in the ultrathin films has been analyzed.