AC/DC characterization of NMOS and PMOS hot-carrier-induced degradation under AC/DC stress

The AC/DC measurements of NMOS and PMOS I/sub dsat/ shifts are compared following DC stress. The results of the I/sub dsat/ shifts are found to be the same. The AC I/sub dsat/ measurements were performed under a variety of different conditions (varying frequency, amplitude, and base level) and showed that hot-carrier-induced interfaced states are shallow and fast (<20 ns). AC versus DC stressing was also examined. In PMOS devices, pulsed drain stress was found to be generally quasi-static, while pulsed gate stress produced enhanced device degradation under certain bias conditions. In NMOS transistors AC drain stress was found to be quasi-static in strong device saturation, while AC gate stress resulted in significantly enhanced degradation. In weak device saturation, both gate and drain pulsing resulted in early catastrophic device failure.<
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