The initial steps of gate oxide wear-out phenomenon were considered using quantum mechanical cluster density functional theory calculations. As was proposed earlier, precursor breakdown defects could be formed due to capture of the injected electrons by localized gap states induced by structural imperfections in SiO2. It was shown here that the electron capture weakened the Si–O bond, which could then be broken due to its polarization and vibrational excitation. In the next step, a donor–acceptor bond between the negatively charged O and neighboring Si atom may be formed creating a chain of

bond swapping. The proposed model suggested a novel mechanism for the formation of paramagnetic defects in the oxides (E’ centers), which could contribute to the formation of a conduction path in the oxide film and its dielectric breakdown. The proposed model describes the observed charge-to-breakdown dependence upon electric field, temperature, electron fluence and oxide thickness.

Atomistic Model of Electric Stress Induced Defect Generation in Silicon Oxide. A.A.Korkin, G.I.Bersuker, H.R.Huff: Computational Materials Science, 2002, 24[1-2], 223-8