Anomalous hot-carrier induced degradation in very narrow channel nMOSFETs with STI structure

Channel width dependence of hot-carrier induced drain current degradation was investigated for nMOSFETs with optimized STI structure in which no MOS hump characteristics were observed. In an STI structure, increase in hot-carrier induced degradation in the narrow channel region was found for the first time. The stress time dependence of the drain current degradation rate increases drastically below 0.5 mu m channel width. This phenomenon is caused by accelerated hot-carrier generation and higher hot-electron injection rate at the channel region adjacent to the STI edge. The lifetime of nMOSFETs with STI structure would be seriously degraded by this phenomenon.