Defects and their passivation in high K gate oxides

High dielectric constant oxides such as HfO2 are very important as gate dielectrics in future CMOS devices. However, compared to SiO2 they suffer from much higher defect concentrations which cause charge trapping, threshold voltage instability, and mobility degradation. The main defect is the oxygen vacancy. It has been found that fluorine is able to passivate these defects to an extent. The mechanism of defect passivation is calculated using ab-initio methods, and the general principles of defect passivation in ionic oxides are discussed.