X-ray photoelectron study of gate oxides and nitrides

X-ray photoelectron spectroscopy can determine the elemental composition, chemical states, and Si non-stoichiometric defects as a function of depth for current gate oxides because the escape depths of the photoelectrons is comparable to the thickness of the oxide. We have shown that annealing of rapid thermally grown oxides decreases the non-stoichiometric fraction of Si as the number of electrical defects grow. Nitrogen implanted into Si before growth of the oxide becomes incorporated at the SiO2/Si interface as the oxide grows, and the concentration of N can be augmented by oxidation in N2O. The distribution of oxygen on the surface after wet chemical cleans changes as the specimen is heated, and does not form a simple overlayer.