Effects of ozone oxidation on interfacial and dielectric properties of thin HfO2 films

The effects of high concentration ozone oxidation at different temperatures on the interfacial and dielectric properties of thin HfO2 films are examined. Analysis of the chemical shifts of the Hf 4f, Si 2p and O 1s core-level spectra acquired by x-ray photoelectron spectroscopy clearly indicates that the introduction of ozone can significantly improve the bonding characteristics between hafnium and oxygen even at low temperature. High-resolution cross-sectional transmission electron microscopy study shows that when the oxidation temperature is increased, film densification and crystallization occur at high temperature. The change in the dielectric properties of high temperature oxidation is analyzed and the results show that a negligible hysteresis and low fixed charge density can be achieved by medium temperature oxidation. When the oxidation temperature is increased to over 800 °C, the dielectric properties degrade due to regrowth of the interfacial layer and change in the film morphology. Our results also reveal that the leakage current can be reduced by high temperature ozone oxidation.