This paper investigates the relationship between hot electron degradation (HED) and substrate current (I-B) by comparing experimental data of 0.1 mum technology devices and Monte Carlo simulation in the low voltage regime. Despite the reduction of the maximum applied voltage below the damage creation energy threshold (E-TH), the experimental data shown here indicate that in sub-0.1 mum technologies operating at low voltage HED lifetime (tau) and I-B are still related by the usual power law relation with an exponent of -3, also found when the applied voltage was well above E-TH. With the help of simulation we show that this power law relation holds true even at low voltage because of the effect of electron-electron scattering on the carrier distribution and the high value of E-TH. It is then concluded that the usual extrapolation technique of HED lifetime as a function of I-B to low voltage is accurate enough for practical purposes.