Oxygen related defects and the reliability of high-k dielectric films in FETs

The interaction between oxygen vacancies and dopant atoms in HfO₂ dielectric were studied using first principles total energy calculations. Beside La dopants also the influence of fluorine and nitrogen atoms has been studied. La dopants in the vicinity of a neutral oxygen vacancy (VO) are more stable compared to the La defects far from VO centers. Furthermore, La atoms lead to a shift of the defect states of oxygen vacancies towards the conduction band edge. A similar but more pronounced effect can be observed by fluorine and nitrogen atoms filling the VO centers. These elements may therefore contribute to the reduction of the gate leakage current and improvement of the device reliability.