Influence of Fin- and Finger-Number on TID Degradation of 16 nm Bulk FinFETs Irradiated to Ultra-High Doses

This paper investigates the fin- and finger-number dependence of the total ionizing dose (TID) degradation in 16 nm bulk Si FinFETs at ultra-high doses. n- and p-FinFETs designed with different numbers of fins and fingers are irradiated up to 500 Mrad(SiO2) and then annealed for 24 h at 100 C. The TID responses of nFinFETs are insensitive to fin number, as dominated by border and interface trap generation in STI and/or gate oxide. However, pFinFETs show a visible fin-number dependence with worst tolerance of transistors with smallest number of fins. The fin number dependence may be related to a larger charge trapping in STI located at the opposite lateral sides of the first and last fins. In addition, both n- and p-FinFETs exhibit an almost TID insensitivity to finger-number. During the design of integrated circuits, the TID tolerance of electronic systems can be enhanced by preferably using transistors with higher number of fins than fingers.