IMPACT OF AGING ON RADIATION HARDNESS

Identifying aging effects that impact radiation hardness of microelect ronics is becoming increasingly important as military weapon systems a re kept in the stockpile for times beyond their originally intended us e period. In this work, burn-in effects are used to demonstrate the po tential impact of thermally-activated aging effects on integrated circ uit radiation hardness. Static random access memories (SRAMs) from thr ee different commercial technologies were irradiated with different pr e-irradiation stress conditions. A reduction in the total dose functio nal failure level was observed for SRAMs from two of the technologies subjected to preirradiation elevated temperature stresses. This is the first time the burn-in effect has been shown to degrade the radiation -induced functional failure level of an IC. SRAM data also show no ind ication that the burn-in effect will saturate, at least for the condit ions examined in this work. These data indicate that long-term aging c an result in more device degradation than is accounted for by present hardness assurance test guidelines, potentially causing device and/or system failure during the aging period. While only a few technologies have been examined to date, we suspect other technologies may exhibit similar long-term aging effects. A technique for including aging effec ts within a hardness assurance test program is outlined.