Comparative study of passivation mechanism of oxygen vacancy with fluorine in HfO_2 and HfSiO_4

摘要

It has been experimentally observed that the incorporated fluorine will greatly improve the reliability of high-permittivity gate dielectric based transistors, but the role of fluorine passivation on leakage current change through gate is still a debated issue. The authors performed first-principles calculations to study the role of fluorine in oxygen vacancies in HfO_2 and HfSiO_4 They found that fluorine behaves completely differently in these two gate dielectrics. Fluorine can passivate the gap states of HfO_2 completely but has no effect on the passivation of oxygen vacancies in HfSiO_4, which is a possible explanation to the controversy surrounding varying leakage current.