Closed form analytical equations For time-dependent dielectric breakdown of the gate oxide under bipolar stress is proposed for the first time. The effect of stress frequency, gate current polarity, and temperature on the time to breakdown is accounted fur in the proposed hole injection detrap model. The lifetime improvement with increasing frequency is mainly due to the competition between the hole trapping process at the forward stress field and hole detrapping process at the reverse stress field. The modeling results show good agreement with the experimental data.