In this paper, a modified charge pumping (CP) technique is proposed to determine the lateral distribution of the interface state density (Nit) near the drain junction of hot-carrier- stressed n-MOSFET's. Basically the rising and the falling slopes of the gate pulse are held constant, and the concept of "local threshold" and "local flatband" voltages are used to extract the relationship between the measured Icp and the charge pumping edge. Several existing papers have proposed CP methods, but they have to differentiate the measured Icp data several times or require accurate doping profiles for the channel and the S/D regions. Therefore, the distribution profile of Nit extracted by these method is not accurate. The new technique determines the charge pumping edge more exactly, and Nit can be extracted directly from experimental charge pumping results. Therefore, this method requires no information about impurity concentrations.