The response of metal-oxide-semiconductor devices irradiated at high temperatures

To study the combined effects of high temperature and radiation on metal-oxide-semiconductor (MOS) integrated circuits (ICs), we have performed a series of experiments to characterize the response of MOS 16k static random access memories (SRAMs) irradiated at temperatures from 298 to 398 K. The irradiations were performed at dose rates approaching those of a spacebased nuclear reactor (approx. = 0.03 rad/s). Over the temperature range investigated, the failure dose of 16k SRAMs was found to decrease with increasing temperature due to complex interactions between radiation and temperature. Neither the failure mechanism nor the failure dose could be predicted from separate or independent measurements of room-temperature irradiation data and IC response preirradiation as a function of temperature. These results show that over the temperature range 298 to 398 K one cannot depend on elevated temperatures to extend the lifetime of ICs in a radiation environment. Extensive qualification tests must be performed if ICs on a space nuclear power platform are to be exposed to high radiation levels in this temperature range. At temperatures much higher than 400 K, however, defect annealing can significantly increase the radiation tolerance of MOS circuits.