In this paper, a physical model is presented for estimating the mean intrinsic breakdown time Of SiO2. Using a general compensation law and assuming that the current-voltage characteristic is dominated by modified Mott-Gurney hopping prior to breakdown, a simple analytical expression for predicting the mean intrinsic breakdown wearout lifetime of oxides can be obtained. The analytical results describe well the following features of the data, (1) a thermal acceleration factor which is a linear function of the stressing electric field and (2) a field acceleration factor that is proportional to reciprocal temperature. The existing closed form expression gives a good fit to experimentally obtained mean intrinsic breakdown time of oxides in the literature. (C) 2002 Elsevier Science Ltd. All rights reserved.