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 shallow trench isolation (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 /spl 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.