A comprehensive investigation of total ionizing dose effects on bulk FinFETs through TCAD simulation

This study investigates the total-ionizing-dose (TID) effect on bulk FinFETs under ON-state irradiation bias, aiming to analyze the cause and physical mechanism of irradiation enhancement effects. Utilizing technology computer-aided design (TCAD), for the first time, we find that parasitic transistors located at the apex of the shallow trench isolation (STI) oxide significantly contribute to the subthreshold degradation of the device, leading to a notable increase in off-state leakage current. Furthermore, under identical irradiation bias conditions, narrower-fin and shorter-channel devices exhibit a more pronounced increase in off-state leakage current. This escalation is attributed to an increased amount of trapped charge in the STI oxide and the elevated electrostatic potential of the punch-through stop (PTS) layer, respectively. Additionally, higher drain voltage reduces the threshold voltage of the STI parasitic transistors, resulting in an increased off-state current as drain voltage rises. In summary, investigating the TID effect of bulk FinFETs under ON-bias is crucial, as it can provide theoretical support for reinforcing nanostructured devices against irradiation-induced degradation.