Underlying physics of the thermochemical E model in describing low-field time-dependent dielectric breakdown in SiO2 thin films

TLDR

The paper presents the underlying physics that explains why the thermochemical E model accurately describes time‑dependent dielectric breakdown in SiO₂ thin films. It shows that dipole‑field coupling of intrinsic defect states lowers the activation energy for thermal bond breakage, and that mixing different disturbed bonding states yields a temperature‑independent field‑acceleration parameter γ and a field‑independent activation energy ΔH. The model’s excellent agreement with long‑term TDDB data confirms that oxygen vacancies are the key intrinsic defect and that the electric field—not current—is the primary driver of breakdown under low‑field conditions, with mixed bonding states producing nearly temperature‑independent γ and field‑independent ΔH.

Abstract

The underlying physics behind the success of the thermochemical E model in describing time-dependent dielectric breakdown (TDDB) in SiO2 thin films is presented. Weak bonding states can be broken by thermal means due to the strong dipolar coupling of intrinsic defect states with the local electric field in the dielectric. This dipole-field coupling serves to lower the activation energy required for thermal bond-breakage and accelerates the dielectric degradation process. A temperature-independent field acceleration parameter γ and a field-independent activation energy ΔH can result when different types of disturbed bonding states are mixed during TDDB testing of SiO2 thin films. While γ for each defect type alone has the expected 1/T dependence and ΔH shows a linear decrease with electric field, a nearly temperature-independent γ and a field-independent ΔH can result when two or more types of disturbed bonding states are mixed. The good agreement between long-term TDDB data and the thermochemical model suggest strongly that the oxygen vacancy is an important intrinsic defect for breakdown and that field, not current, is the primary cause of TDDB under low-field conditions.