Reversible and irreversible degradation attributing to oxygen vacancy in HfSiON gate films during electrical stress application

The dielectric degradation under electrical stress application was attributed to generation of oxygen vacancy, and structural transformation in HfSiON films, in addition to widely known charge trapping. The former two result from ion drift under electrical field due to its ionic character of Hf-based dielectrics. While V o generation and charge trapping are atomic-range phenomena, it is surprising that long-range structural transformation can also occur under electrical filed before dielectric breakdown even at room temperature.