Breakdown properties of irradiated MOS capacitors

We have studied the effects of ionizing and non-ionizing radiation on the breakdown properties of different types of MOS capacitors, with thick (200 nm) and thin (down to 8 nm) oxides. In general, no large variations of the average breakdown field, time-to-breakdown at constant voltage, or charge-to-breakdown values have been observed after high dose irradiation (20 Mrad(Si) 9 MeV electrons on thin and thick oxides, 17(Si) Mrad Co60 gamma and 1014 neutrons/cm2 only on thick oxides). However, Some modifications of the cumulative failure distributions have been observed in few of the oxides tested.