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

Abstract

The total ionizing dose (TID) response of double-gate SiGe- ${{\rm SiO}_2}/{{\rm HfO}_2} \ p$ MOS FinFET devices is investigated under different device bias conditions. Negative bias irradiation leads to the worst-case degradation due to increased hole trapping in the ${{\rm HfO}_2}$ layer, in contrast to what is typically observed for devices with ${{\rm SiO}_2}$ or ${{\rm HfO}_2}$ gate dielectrics. This occurs in the devices because radiation-induced holes that are generated in the ${{\rm SiO}_2}$ interfacial layer can transport and become trapped in the ${{\rm HfO}_2}$ under negative bias, leading to a more negative threshold voltage shift than observed at 0 V bias. Similarly, radiation-induced electrons that are generated in the ${{\rm SiO}_2}$ interfacial layer can transport into the ${{\rm HfO}_2}$ and become trapped under positive bias, leading to a more positive threshold voltage shift than observed at 0 V bias.