Exposure-Dose-Rate-Dependence for a CMOS/SOS Memory

This study of a 1K RAM demonstrated the basic recovery characteristics previously reported in the literature for MOS capacitors and transistors. High exposure-rate-tests (i.e. 5.3 × 105 rads (Si)/(hr) indicated low-failure-doses of 1 kilorad (mean value of Pass/Fail range) in space qualified memories. The most significant failure effect was identified as due to back-channel-leakage which was traceable to starting substrates. Reduction of exposure rate from 5.3 × 105 to 5.9 rads (Si)/hr increased the minimum-failure-dose to 4.5 kilorads. This improvement could not be predicted by the use of Convolution theory.