Characterization of short and narrow channel effects for CAD-IGFET model

WHEN THE CHANNEL LENGTH L and gate width W of IGFETs become comparable to the width of the depletion regions surrounding the channel, the associated fringing fields make the threshold voltage VT dependent on L and W. Past efforts have analyzed simplified device structures to relate VT to L1 or both L and W2. The resulting equations reveal the device physics, but are complex and more significantly, their parameters are not simple to measure. The approach taken here has been to incorporate heuristically these geometrical dependencies into the classical VT expression using empirical parameters which are measured from terminal biases and have physical meaning.