Enhanced TID susceptibility in sub-100 nm bulk CMOS I/O transistors and circuits

This paper evaluates the radiation responses of 2.5 V I/O transistors and regular-threshold MOSFETs from a 90 nm commercial bulk CMOS technology. The data obtained from ⁶⁰Co ionizing radiation experiments indicate enhanced TID susceptibility in I/O devices and circuits, which is attributed to the p-type body doping. A quantitative model is used to analyze the effects of doping and oxide trapped charge buildup along the sidewall of the shallow trench isolation oxide. These effects are captured in the general electrostatic equation for surface potential, which can be correlated to off-state leakage current. Device simulations are used in concert with experimental measurements and the analytical model to provide physical insight into the radiation response of each device type.