Two-stage hot-carrier degradation and its impact on submicrometer LDD NMOSFET lifetime prediction

Abstract

The device degradation of oxide-spacer LDD NMOSFET's due to hot carriers is studied in detail. The observed saturation in the degradation time dependence is found to be due to a combination of an increase in the series resistance in the lightly doped drain region, and a reduction of the carrier mobility in the channel and subdiffusion regions. The increase in series resistance eventually saturates. Thus, a more accurate and consistent value of LDD NMOSFET lifetime can be determined using extrapolations which are based on the asymptotic value of the degradation rate coefficient. >