An X-ray photoelectron spectroscopy study of strontium-titanate-based high-k film stacks

Abstract: Stoichiometric and Sr-rich strontium-titanate (STO) nanofilms grown on thin TiN layers over SiO2/Si were studied by X-ray photoelectron spectroscopy (XPS) at two analyzer exit angles, both as-deposited and after rapid thermal annealing (RTA) at 650°C in N2. Individual layer thickness and composition, mutually dependent via the electron transport properties of the film matrix, were iteratively obtained using a set of empirical relative sensitivity factors (RSF), as well as inelastic mean free paths with their elastic corrections, as per ISO18118:2004(E). Successive layer thicknesses and average Sr/Ti atomic ratios were consistent with the nominal description of the samples, provided a superficial SrCO3 phase inadvertently formed over STO during growth is taken into account. This phase was strongly reduced upon RTA, with considerable compacting of the STO layers. [Copyright &y& Elsevier]