Transient Radiation Effects in SOI Static RAM Cells

Recent transient radiation experiments have shown a substrate bias dependence on the logic upset levels of a silicon-on-insulator (SOI) technology. From this data, it was concluded that secondary photocurrents generated by the parasitic bipolar junction transistors (BJTs) were responsible for the observed difference in the bias dependent transient radiation induced upset thresholds. In this report we present our results obtained from computer simulations of the transient radiation response of the SOI technology. These results support a possible explanation for the bias dependent logic upset levels experimentally observed. Parasitic BJT gain calculations, gain modulation and substrate bias effects on transient upset thresholds in static random access memory (SRAM) cells are discussed.