The effects of weak gate-to-drain(source) overlap on MOSFET characteristics

Recent studies showed that minor structural differences in the gate-to-drain (source) overlap of a MOSFET has unexpectedly strong influence on its characteristics. As the overlap is weakened, the drain drive degrades, the substrate and gate currents show abnormal behaviors, and the device lifetime suffers. A simple physical model is presented that adequately explains most of these observed high-field effects, including the asymmetry in device properties. Implications of the wear-overlap phenomena on future process and device designs are discussed.