Bias Dependence of Total Ionizing Dose Effects in SiGe-MOS FinFETs

The total ionizing dose (TID) response of double-gate SiGe-SiO₂/ HfO₂ \ pMOS FinFET devices is investigated under different device bias conditions. Negative bias irradiation leads to the worst-case degradation due to increased hole trapping in theHfO₂layer, in contrast to what is typically observed for devices withSiO₂orHfO₂gate dielectrics. This occurs in the devices because radiation-induced holes that are generated in theSiO₂interfacial layer can transport and become trapped in theHfO₂under negative bias, leading to a more negative threshold voltage shift than observed at 0 V bias. Similarly, radiation-induced electrons that are generated in theSiO₂interfacial layer can transport into theHfO₂and become trapped under positive bias, leading to a more positive threshold voltage shift than observed at 0 V bias.