Depth profiles of Ta2O5/SiO2/Si structures : a combined X-ray photoemission, Auger electron, and secondary ion mass spectroscopic study

Abstract

We prepared thin films of tantalum oxide on SiO2/Si substrates by thermal oxidation of tantalum. The different oxide layers and their interfaces were characterized by SIMS, AES, and XPS. Characteristic structures were obtained after different oxidation procedures. The comparative discussion of AES and SIMS depth profiles makes possible an unequivocal characterization of the reactive interfaces between the oxides of Ta and Si. The Ta2O5/SiO2 interface in particular shows non-stoichiometries which depend on the oxidation procedures and which determine the performance characteristics of pH-sensitive Ta2O5 field-effect transistors.