Hot carrier effect of AC stress on P-MOSFETs

The hot carrier degradation under the AC stress was compared with that under the DC stress for the surface channel P-MOSFETs having 0.5μm gate length and 10mm gate oxide. The shift direction of drain current and threshold voltage becomes positive by the Drain Avalanche Hot Electron (DAHE) injection as the gate pulse voltage approaches the gate voltage with the maximum gate current and the shift direction gets negative by the Channel Hot Hole (CHH) injection as the gate pulse approaches the drain voltage. Moreover the shift direction depends not only on the pulse height but also on the rise/fall time as well as the frequency of the gate pulse as the peak voltage approaches the drain voltage since the ratio of the CHH injection time to the DAHE injection time is varied by these parameters.