Investigation of an Mo/SiO2 interface by electron-induced x-ray emission spectroscopy

Abstract

We have studied the solid/solid interface between Mo and SiO 2 films deposited, respectively, by magnetron d.c. sputtering and plasma-enhanced chemical vapour deposition (PECVD). The sample depth profile was characterized by SIMS. We used electron-induced x-ray emission spectroscopy to characterize the interface from the valence Si 3p and O 2p spectral densities, which are very sensitive to the physicochemical environment, and the Si 2p → Is transition, which is sensitive to the oxidation degree of the silicon atoms. By gradually decreasing the emissive thickness, which is a function of the primary electron energy, we have shown the presence of an interfacial compound 2-4 nm thick that is not seen by SIMS. We suggest that this compound is an Mo-Si-O mixed oxide in which the silicon atoms have an oxidation degree equal or close to that of silica.