MOSFET EFFECTIVE CHANNEL LENGTH, THRESHOLD VOLTAGE, AND SERIES RESISTANCE DETERMINATION BY ROBUST OPTIMIZATION

MOSFET parameters, such as effective channel length, series resistances, and channel mobility, are important for process control and device design. These parameters are typically obtained from intercepts and slopes of plots of intermediate quantities, such as peak transconductance, derived from I-V data. Commonly, the intercept of a plot is found by extrapolation. However, the extrapolation process is sensitive to measurement errors. In addition, the plots often show nonlinear behavior, hence slopes and intercepts cannot be determined accurately. In this paper we show how these problems can be overcome by using a nonlinear optimization procedure to determine these MOSFET parameters, by explicitly identifying them as the parameters of a simple, widely used MOSFET model that is a good approximation in the triode region of operation. We also report the results of five tests of robustness and accuracy that show that our method is significantly more accurate and robust than the Ciofi et al., peak g(m), Suciu-Johnston, Terada-Muta, Chern et al., Whitfield, and 1/beta-methods.