Thermal stability of an ultrathin hafnium oxide film on plasma nitrided Si(100)

We report on the thermal stability of an ultrathin hafnium oxide film on a plasma nitrided Si(100) surface. The ultrathin silicon nitride buffer layer was produced by an ECR-plasma ion source. Onto this buffer layer a thin hafnium oxide film was prepared by electron beam evaporation. The thermal stability of the layer stack was checked by systematic annealing steps. A detailed angle resolved X-ray photoelectron spectroscopy study of the interfaces is presented. For chemical surface studies high-resolution spectra of the Si 2p and Hf 4f signals were taken. It is demonstrated that the thermal stability of hafnium oxide thin films can be increased by a smooth and homogenous buffer layer of silicon nitride.