Charge Generation by Secondary Particles From Nuclear Reactions in BEOL Materials

Direct charge collection measurements are presented, which prove that the presence of tungsten near sensitive volumes leads to extreme charge collection events through nuclear reactions. We demonstrate that, for a fixed incident particle linear energy transfer (LET), increasing particle energy beyond a certain point causes a decrease in nuclear reaction-induced charge collection. This suggests that a worst-case energy exists for single-event effect (SEE) susceptibility, which depends on the technology, device layout, and the incident ions' fixed LET value. A Monte Carlo approach for identifying the worst-case energy is applied to certain bulk-Si and silicon-on-insulator (SOI) technologies. Simulation results suggest that the decrease in charge collection beyond the worst-case energy occurs because the secondary particles produced from the high-energy nuclear reactions have less mass and higher energy and are therefore less ionizing than those produced by lower-energy reactions.