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

•Thin films of HfO2 and Si3N4 were deposited on Si by EBE and ECR plasma source.•Thermal stability was investigated in a temperature range from T = 500°C to 800°C.•Buried interfaces of the system were investigated by ARXPS.•We demonstrate the thermal stability of the hafnium oxide film up to T≈750°C.

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.