Bias dependence of TID radiation responses of 0.13 μm partially depleted SOI NMOSFETs

The bias dependence of total ionizing dose (TID) radiation responses of 0.13 μm Partially Depleted (PD) SOI NMOSFETs is presented. Experiments and three dimensional (3D) simulations are used to analyze the buildup of trapped charge in the STI oxide as well as in the buried oxide (BOX) and its impact on the negative shift of back-gate threshold voltage and subthreshold hump. It is demonstrated that the worst-case bias conditions for the largest back-gate threshold voltage shift and increase of the off-state leakage current (or the negative shift of back-gate subthreshold hump) are different. The radiation-induced positive trapped charge in the BOX can fully deplete the body silicon for input/output (I/O) NMOSFETs as a result of the lower body doping concentration, giving rise to the coupling effect between the front-gate and back-gate threshold voltage shift.