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 photoelect ron spectroscopy (XPS) and X-ray Anger electron spectroscopy (XAES). T he spectra of Si2p XPS and Si(KLL) XAES were measured precisely and we re deconvoluted into some separate peaks, which correspond to each par ent phase, a SiOxNy oxidized phase, a nonstoichiometric SiNx nitride p hase, and a satellite peak of the parent phase, by the least-squares m ethod. The Auger parameter (AP) was calculated for each phase using th e Si2p XPS and Si(KLL) XAES data, and the average chemical composition s of the oxidized phases in each sample were evaluated from the AP dat a. The chemical compositions of these phases mere between those of sil ica and silicon oxynitride and varied among the samples, but were usua lly 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 oxidiz ed phase against the parent phase of the XAES spectra, assuming a cont inuous surface layer model.