In this study, a new method to characterize the n(+)-polysilicon/oxide interface trap state by measuring the gate voltage-gate leakage current (Vg-Jg) characteristics under the low electric field is developed. These traps are neutral and consist of the fast and slow trap states located near the Fermi level of the n(+)-polyoxide. We use the first order rate equation to characterize the relationship between the gate leakage current and the gate voltage sweep rate. A simple formula to characterize the detrapping behavior of the slow trap states with the detrapping time constant was derived. It is important to find that the smaller detrapping time constant observed in a thinner oxide (2.5 nm) is due to the field enhanced detrapping effect.