Implications of waveform and thickness dependence of SiO2 breakdown on accelerated testing

Oxide breakdown characteristics under accelerated test conditions are different from those under normal operating conditions. While oxide lifetime under unipolar pulse stress is roughly equal to the DC lifetime multiplied by the reciprocal of the duty cycle, lifetime under bipolar pulse stress is extended by an additional factor of 40 or more. At the high electric fields used during accelerated testing, oxides with thickness greater than 15 nm suffer lifetime degradation which may be attributed to hole trapping. This will lead to overly conservative projections of lifetime under normal operating conditions