Relation between degradation and breakdown of thin SiO 2 films under AC stress conditions

Abstract

MOS capacitors have been subjected to bipolar voltage waveforms of different amplitudes and frequencies. The current density measured under a DC low-value gate voltage is taken as an indicator of the oxide degradation level, so that its evolution is taken as a measure of the progressive wearout of the oxide. The data suggest lower degradation levels, for the same stress times, at high frequencies. This is consistent with the increase of the time-to-breakdown with frequency and confirms that, also for dynamic stresses, the relation between degradation and breakdown is fundamental to understand the physics of dielectric breakdown.