Quantitatuve analysis of ultrathin SiO2 interfacial layer by AES depth profiling

Abstract

When a TaO5 dielectric film is deposited on a bare silicon, the growth of SiO₂ at the TaO5/Si interface cannot be avoided. Even though the SiO₂ layer is ultrathin (a few nm), it has great effects on the electrical properties of the capacitor. The concentration depth profiles of the ultrathin interfacial SiO₂ and SiO2/Si3N4 layers were obtained using an Auger electron spectroscopy (AES) equipped with a cylindrical mirror analyzer (CMA). These AES depth profiles were quantitatively analyzed by comparing with the theoretical depth profiles which were obtained by considering the inelastic mean free path of Auger electrons and the angular acceptance function of CMA. The direct measurement of the interfacial layer thicknesses by using a high resolution cross-sectional TEM confirmed the accuracy of the AES depth analysis. The SiO2/Si3N4 double layers, which were not distinguishable from each other under the TEM observation, could be effectively analyzed by the AES depth profiling technique.