CHARACTERIZATION OF SURFACE-OXIDIZED PHASE IN SILICON-NITRIDE AND SILICON OXYNITRIDE POWDERS BY X-RAY PHOTOELECTRON-SPECTROSCOPY

Surface-oxidized phases on alpha-silicon nitride, beta-silicon nitride, and silicon oxynitride powders were investigated by X-ray photoelectron spectroscopy (XPS) and X-ray Anger electron spectroscopy (XAES). The spectra of Si2p XPS and Si(KLL) XAES were measured precisely and were deconvoluted into some separate peaks, which correspond to each parent phase, a SiOxNy oxidized phase, a nonstoichiometric SiNx nitride phase, and a satellite peak of the parent phase, by the least-squares method. The Auger parameter (AP) was calculated for each phase using the Si2p XPS and Si(KLL) XAES data, and the average chemical compositions of the oxidized phases in each sample were evaluated from the AP data. The chemical compositions of these phases mere between those of silica and silicon oxynitride and varied among the samples, but were usually close to SiO2. Average thicknesses of the surface-oxidized phases were estimated to be 0.1-0.8 nm from the peak area ratio of the oxidized phase against the parent phase of the XAES spectra, assuming a continuous surface layer model.