Study of interactions of Hf and SiO₂ film for high-k materials

Hf adsorption on thin SiO₂ films was carried out using an ultrahigh-vacuum system with e-beam evaporation. The interaction of adsorbed Hf and SiO₂ films was studied by Auger electron spectroscopy (AES), atomic force microscopy (AFM), and current-voltage (I-V) measurements. The leakage current of the SiO₂ films increased with Hf adsorption temperature. The dielectric properties of the SiO₂ layer were markedly degraded by Hf adsorption even at 300°C. Additionally, Hf adsorbed on a SiO₂ (6.3 nm)/Si substrate at 900°C penetrated through the SiO₂ layer and reacted with the Si substrate forming large concavities. Otherwise, Si diffused from the SiO₂/Si interface to the surface of adsorbed Hf.