A new characterization method is proposed to study the relationship between the hot-carrier-induced interface state Nit (x) and the device drain current degradation of submicron LDD n-MOSFET's. In this method, by making use of the conventional charge pumping measurement in combination with the power-law dependence of interface damages on stress time, the spatial distribution Nit(x) and the effective damaged length Ldam can be easily extracted. The time evolution of the interface state generation and its correlation with the device degradation can then be well explained. It is worthwhile to note that this newly-developed method requires no repetitive charge pumping measurements, and hence avoids he likely imposition of re-stress on tested devices. By combining the characterized Ldam and Nit quantitatively, the results show that the damage at VGS ≈ VDS/2 is most highly localized among various stress biases, which can explain why the generated interface states will dominate the device drain current degradation at this bias after long-term operating conditions.