Anomalous Negative Bias Temperature Instability Degradation Induced by Source/Drain Bias in Nanoscale PMOS Devices

The effect of source/drain (S/D) bias on the negative bias temperature instability (NBTI) of pMOSFETs is studied. The anomalously enhanced NBTI under S/D bias conditions is observed, which cannot be explained by the conventional reaction-diffusion model. A new mechanism based on the enhanced interfacial dissociation of equivSi-H bonds induced by the energetic holes (the hole energy E _h is higher than the reaction activation energy E _a of equivSi-H bond dissociation) is proposed to address the observed degradation behaviors. Monte Carlo simulations are used to identify the validity of the new mechanism.