High temperature N2 annealing - a promising way for improving the structure of Ta2O5 and its interface with Si

The effect of N₂ annealing at 1123 K for 30 min on the structural characteristics of thin (15 nm) thermal Ta₂O₅ layers on Si was examined by X-ray photoelectron spectroscopy. The results indicate that the annealing improves the stoichiometry and microstructure of both the bulk oxide and the interfacial region, which manifests as a reduced amount of suboxides. The interfacial region is a composite oxide of suboxides of Ta and Si before and after N₂ treatment but the annealing reduces the excess Si and decreases the width of the interface. Thus a trend to more abrupt interface is observed.