AES AND XPS STUDY OF THIN RF-SPUTTERED TA2O5 LAYERS

The elemental composition and the chemical bonding in RF-sputtered tantalum oxide (4-75 nm) on Si, obtained by reactive sputtering of Ta in an Ar-O-2 mixture, have been studied by AES and XPS. The influence of the gas composition (O-2 content in the gas mixture 0.1%-50%) and of the substrate temperature (300 or 493 K) during the film deposition have been studied. The effect of post-deposition annealing in dry O-2 has also been considered. The results indicate that a content of 10% O-2 favours the formation of stoichiometric Ta2O5 and an abrupt interface transition region between Si and Ta2O5. The annealing effect depends strongly on the quality of the as-deposited layer, it leads basically to homogenization of the layers and improves additionally the stoichiometry of non-perfect oxides.