Channel Length Dependence of the Body-Factor Effect in NMOS Devices

The dependence of threshold voltage on substrate bias in NMOS devices is reevaluated in the light of a large sample of data for short-channel length devices (0.8 ?m < L < 8 ?m). Existing models [1], [2] do not fit the data with the necessary accuracy for circuit simulation of short channel devices. A new model involving only process parameters is presented which may also be used to evaluate xj and Nsub from a limited amount of observations if long channel devices are not available. Agreement with SUPREM is excellent.