Nonlinear composition dependence of x-ray photoelectron spectroscopy and Auger electron spectroscopy features in plasma-deposited zirconium silicate alloy thin films

The local bonding of Zr, Si, and O atoms in plasma-deposited, and post-deposition annealed Zr silicate pseudobinary alloys [ (ZrO2)(x)(SiO2)(1-x)] was studied by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Systematic decreases in XPS binding energies, and increases in AES kinetic energies with alloy composition x are consistent with an empirical chemical bonding model based on electronegativity equalization; however, there are significant departures from the predicted linear composition dependencies of that model. Deviations from linearity in the XPS compositional dependencies are correlated with dipolar network atom fields as determined from ab initio calculations. The nonlinearities in the x dependence of Zr-MVV and O-KVV AES spectral features are determined primarily by oxygen-atom coordination dependent shifts in valence band offset energies. The energy spread in the compositional dependence of binding energies (similar to 1.85 eV) for the XPS Zr 3d(5/2) and Si 2p features combined with x-ray absorption spectroscopy data indicates that the conduction band offset energies between the Si substrate and Zr silicate dielectrics are alloy composition independent. Changes in O 1s XPS features in alloys with xsimilar to0.3 to 0.6 as function of annealing temperature are consistent with a previously identified chemical phase separation that occurs after 60 s anneals at 900 degreesC in a nonoxidizing ambient, Ar. (C) 2002 American Vacuum Society.