Mixed-Mode Simulation and Analysis of Digital Single Event Transients in Fast CMOSICs

Single event transient (SET) pulses produced from heavy ion irradiation in digital integrated circuits (ICs) are modeled and analyzed using a mixed-mode approach, that is, three-dimensional (3-D) semiconductor device simulation coupled with a circuit solver. In this paper, we analyze the factors affecting the generation and propagation of digital SET pulses in fast CMOS ICs. Our mixed-mode simulations of various ion strike locations allowed to obtain agreement with measured data and explain the earlier published wide distribution of SET pulse widths created by heavy ion radiation in digital CMOS ICs at a given linear energy transfer (LET) value, which was observed experimentally, but not fully understood. We also indicate that the transient charge-collection current pulse (width and shape) on the struck device node is not directly related to the SET voltage pulse that will propagate through a logic circuit, and therefore current pulses alone should not be treated as a measure of DSET.