Bias Dependence of Total-Dose Effects in Bulk FinFETs

The total ionizing dose response of triple-well FinFETs is investigated for various bias conditions. Experimental results show that irradiation with the transistor in the OFF state with the drain terminal high is the worst-case bias configuration. TCAD simulations are used to analyze the buildup of trapped charge in the trench isolation oxide and its impact on the increase in leakage current and subthreshold-slope degradation. The electric field distribution along the STI/fin boundary exerts a strong influence on the trapped charge in the isolation oxide, which induces a parasitic leakage current path at total ionizing doses of less than 200 krad(SiO₂).