Impact of aging on radiation hardness[CMOS SRAMs]

Identifying aging effects that impact radiation hardness of microelectronics is becoming increasingly important as military weapon systems are kept in the stockpile for times beyond their originally intended use period. In this work, burn-in effects are used to demonstrate the potential impact of thermally-activated aging effects on integrated circuit radiation hardness. Static random access memories (SRAMs) from three different commercial technologies were irradiated with different pre-irradiation stress conditions. A reduction in the total dose functional failure level was observed for SRAMs from two of the technologies subjected to pre-irradiation 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 indication that the burn-in effect will saturate, at least for the conditions examined in this work. These data indicate that long-term aging can 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. Technique for including aging effects within a hardness assurance test program is outlined.