Ultra-High Total Ionizing Dose Effects on MOSFETs for Analog Applications

This article investigates the effect of ultra-high total ionizing dose up to 450 Mrad(SiO2) on 180-nm MOSFETs for analog applications. In particular, it studies the influence of the transistor size, design, type, bias, and the annealing on radiation-induced degradation. It studies the radiation effects on three parameters: the drive current, the threshold shift, and the leakage current. First, it reveals radiation-induced short-channel effects (RISCEs), which were until now only observed on more advanced technology nodes, and highlights that its mechanism of apparition differs from these advanced nodes. Second, it highlights the importance of bias during irradiation, not only on the magnitude of these effects but also on the type of defects at their origin. In particular, it demonstrates that the bias during irradiation plays a major role in the n-MOS–p-MOS dissymmetry. Third, it points out the capacity of the ELT and the butterfly rad-hard designs to mitigate the radiation-induced narrow channel effect (RINCE), the LPT, and several other radiation-related issues. Finally, it shows that the 3.3-V designs, compared to the 1.8-V designs, present a larger sensibility to radiation due to their thicker gates, but that they could stay a better choice for analog applications up to 400 Mrad(SiO2), thanks to their larger voltage range.