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Temperature dependence of substrate current (Isub) and hot carrier lifetime in sub 0.25 km NMOS devices has been evaluated at elevated temperatures. Unlike conventional behavior, for scaled devices Isub is found to increase with temperature at low drain bias. The transition point to the new behavior is found to be bias and temperature dependent. The correlation between hot carrier lifetime and Isub has been found to still hold in the new regime. At Vd=lSV, this results in 4x lower lifetime at 125C versus 25C. The lucky electron model is found not to explain the new observations. These findings are consistent with previously reported results on Isub at reduced temperatures and the modeling of statistical distribution of carrier energy at low drain bias. IntroductionIt is well known that under favorable bias conditions, energetic (hot) carriers in MOS devices result in parametric degradation due to damage in the gate oxide and its interface with the channel. Additionally, hot carriers cause impact ionization which results in flow of Isub. Therefore, Isub has traditionally been used as a correlating parameter and a monitor for hot carrier induced degradation. Correlation of Isub with hot-carrier lifetime has been shown to hold while varying many stress conditions and device parameters including temperature, bias, channel length, and dynamic stressing [ 1,3], therefore, making it possible to extrapolate lifetime to a wide range of operating conditions.Historically, elevated temperatures resulted in a decrease in Isub (and hot carrier damage) [2,4] due to two factors, namely, reduction of number of hot carriers (Id reduction) and reduction of carrier energy. Both factors result from