Laser Visualization of the Development of Long Line-Type Mutli-Cell Upsets in Back-Biased SOI SRAMs

An interesting multiple-cell upset (MCU) phenomenon in silicon-on-insulator (SOI) static random access memorys (SRAMs) featuring long lines of more than ten flipped cells is studied. Such an abnormal MCU phenomenon was recently observed for back-biased SOI SRAMs in a heavy-ion test. Using a two-photon absorption-based laser system, we performed fixed-point observations and visualized the development of long line-type MCUs with increasing back bias. The visualization results provided insights to elucidate the mechanism behind these phenomena. Furthermore, using fixed-point observations, we extracted the length of MCUs for various bias conditions and laser strike positions. It was found that for all cases studied, the line length could be explained using an analytical model.