The effects of silicon nitride and silicon oxynitride intermediate layers on the properties of tantalum pentoxide films on silicon: X-ray photoelectron spectroscopy, X-ray reflectivity and capacitance-voltage studies

Thin dielectric films (similar to4.0 nm) of Ta2O5 were prepared by ion beam deposition technique onto Si(I 0 0) without and with a buffer layer of silicon nitride and oxynitride of about I nm. The composition of the films, submitted to annealing at 850 degreesC in nitrogen/oxygen atmosphere was studied by X-ray photoelectron spectroscopy. The thickness and roughness of layers were determined by a best squares fitting routine, based upon the algorithm of Parrat, of the X-ray reflectivity spectra. From capacitance as a function of voltage measurements we analyze the dielectric properties of these samples. We observed that after annealing the intermediate layer of silicon nitride or oxynitride confers to the samples a greater thermal stability in composition and thickness together with an improvement of the electrical properties especially for the sample deposited onto pure silicon nitride that has a dielectric constant of about 18 and an equivalent thickness of I nm. (C) 2003 Elsevier B.V. All rights reserved.