Accuracy of effective channel-length extraction using the capacitance method

A comparison of two different methods for measuring the effective channel length of a MOSFET has been made. It has been determined the effective channel length obtained by the direct capacitance method depends on doping concentration and concentration gradient of the source-drain junctions. Due to the inner fringing capacitance and turn-on of the source-drain regions, the capacitance method tends to predict a longer effective channel length as compared to the resistance method.