Thermal stability of a thin HfO2/ultrathin SiO2/Si structure:: Interfacial Si oxidation and silicidation

We examine the thermal stability of a 2.6-nm-HfO2/0.3-nm-SiO2/Si structure in O-2 pressure and in an ultrahigh vacuum. The temperature and O-2-pressure dependence of Si oxidation at the, HfO2/Si interface indicates that high-vacuum conditions are required to suppress interfacial oxidation (order of 10(-7) Torr at 800degreesC). The void nucleation of Hf silicide (<1000 cm(-2)) takes place at temperatures higher than 900degreesC, which raises the issue of failure when HfO2 film is used in metal-insulator-semiconductor devices.