A Study of High-Voltage p-Type MOSFET Degradation Under AC Stress

In this paper, the degradation characteristics of high-voltage (HV) p-type MOSFETs are investigated during negative unipolar ac stress on the gate electrode. The threshold voltage under ac stress is shifted gradually by both the negative-bias temperature-instability mechanism and Fowler-Nordheim degradation. We qualitatively analyze the degradation characteristics of HV p-type MOSFETs under ac stress, and observe the threshold voltage saturation for HV p-type MOSFETs at long ac stress. Based on the effects of temperature and duty cycles, we offer a suitable model of degradation saturation after long ac stress, which is caused by interface trap saturation and recovery during pulse delay timing, which is dependent on thermal activation energy.