The Impact of Multiple-Cell Charge Generation on Multiple-Cell Upset in a 20-nm Bulk SRAM

Single-event upsets induced by multiple-cell charge generation are studied in a 20-nm bulk SRAM by performing laser irradiation tests. The single-pulse two-photon absorption is utilized to simulate charge generation over multiple SRAM cells. The analysis of fail bit maps reveals that the physical topology of fail bits strongly depends on data patterns stored in SRAM cells. Our results indicate that potential perturbations in multiple p-wells play a key role in determining fail bit patterns. A novel multiple-cell upset mechanism, named multi-well coupled potential unbalancing, is proposed based on the consideration of the unbalanced activation of parasitic bipolar effects. The dominance of this mechanism is confirmed through multiple-pulse irradiation tests.