Gate-voltage-dependent effective channel length and series resistance of LDD MOSFET´s

A measurement algorithm to extract the effective channel length and source-drain series resistance of MOSFET´s is presented. This extraction algorithm is applicable to both conventional and LDD MOSFET´s. It is shown that the effective channel length and the source-drain series resistance of an LDD device are gate-voltage dependent. The effective channel length of an LDD device is not necessarily the metallurgical junction separation between the source and drain as it is commonly seen in a conventional device. A more generalized interpretation of effective channel length is introduced to understand the physical meaning of this gate-voltage dependence. The result also indicates that the effective channel length and source-drain resistance are two inseparable device parameters regardless of LDD or conventional FET´s.