RELATION BETWEEN DEGRADATION AND BREAKDOWN OF THIN SIO2-FILMS UNDER AC STRESS CONDITIONS

MOS capacitors have been subjected to bipolar voltage waveforms of dif ferent amplitudes and frequencies. The current density measured under a DC low-value gate voltage is taken as an indicator of the oxide degr adation level, so that its evolution is taken as a measure of the prog ressive wearout of the oxide. The data suggest lower degradation level s, 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 brea kdown.