3-DIMENSIONAL NUMERICAL-SIMULATION OF SINGLE EVENT UPSET OF AN SRAM CELL

Charge collection mechanisms in PMOS and NMOS transistors irradiated by single energetic heavy ions and the corresponding response of an SRAM cell have been simulated. For an ion track through a p-channel, the RC network within the cell and the strength of the n-channel pull-down device will limit the amount of charge collected. In the case of the n-channel pull-down device, the direction of the ion strike (toward or away from the source) plays a major role in the upset of the cell. An ion path toward the source upsets at a lower LET than one away from the source. This is the result of additional electrons injected from the source due to barrier lowering.