Total dose radiation effects on CMOS ring oscillators operating during irradiation

Total dose radiation effects on propagation delay time were discussed, utilizing 1.5-µm CMOS/SOS ring oscillators with substrate electrodes, irradiated to 10
⁵
rad (Si) with power on. Propagation delay times after irradiation have been successfully predicted by circuit simulation, based on experimental NMOS and PMOS threshold shift data including gate bias dependence during irradiation. It has also been found that the substrate bias condition during irradiation significantly affects post-rad device characteristics. The importance of taking into account substrate bias condition during irradiation in regard to an irradiated scaled circuit performance prediction, is discussed based on the above mentioned results.