Mechanisms Leading to Single Event Upset

SRAM cell recovery time following a 140 MeV Krypton strike on a Sandia SRAM is modelled using a two-dimensional transient numerical simulator and circuit code. Strikes at both n- and p-channel "off" drains are investigated. Four principle results are obtained. The recovery time after a strike is strongly dependent on the drive of the restoring transistor. A struck "off" p-channel drain-to-gate capacitive coupling has a significant effect on recovery in SRAM with feedback resistors. Recovery time is approximately linear with LET over LET in the range to 0.4 pC/μ. Finally, an experimental n-channel SEU has been observed in a Sandia SRAM without feedback resistors.