XPS sputter depth profiling of the chemical states for SrTiO3/Si interface by O-2(+) ion beams

Abstract

Because the chemical states of the elements in SrTiO3 thin film on Si are reduced by argon ion beam bombardment, it was impossible to sputter depth profile the chemical states of SrTiO3 thin film by argon ion beams, In this paper, it is reported that the undistorted chemical states of Ti and Si at the SrTiO3/Si interface can be determined with oxygen ion beams at the appropriate 70 degrees angle of incidence, with which either metallic Ti is not oxidized or Ti in SrTiO3 is not reduced, Under the sputter depth profiling conditions, the chemical state of Ti at the SrTiO3/Si interface could be successfully characterized and the effects of post-annealing at high temperature on the chemical state of Ti were studied, A significant number of Ti atoms in the metallic state were observed at the SrTiO3/Si interface without any post-annealing but all of them were oxidized to the Ti4+ chemical state after 2 h post-annealing at the temperatures above 600 degrees C under oxygen flow, The dielectric properties of SrTiO3 thin films on Si were well correlated to the oxidation state of Ti and the broadening of the interface SiO2 layer induced by post-annealing at high temperature.