Test procedures for proton-induced single event latchup in space environments

The effect of high energy proton irradiation and angle of incidence on single-event latchup (SEL) hardness is investigated as a function of temperature and power supply voltage to determine worst-case hardness assurance test conditions for space environments. SRAMs from several vendors were characterized for single-event latchup SEL hardness at proton energies from 20 to 500 MeV at temperatures of 25 and 80degC, and at both normal and grazing angles of incidence. For all SRAMs investigated, the largest SEL cross section is observed for irradiation with protons with energies larger than 200 MeV. In addition, it is shown that for proton with energies ges 400 MeV, there is not a significant increase in SEL cross section for grazing angles of incidence compared to normal incidence irradiation. Based on the results of several years of research, in addition to these new results, we propose a hardness assurance test procedure for qualifying parts for use in proton-rich space environments.