INVERSE-NARROW-WIDTH EFFECTS AND SMALL-GEOMETRY MOSFET THRESHOLD VOLTAGE MODEL

An analytical threshold voltage model is developed based on the results from a three-dimensional MOSFET simulator, called MICROMOS. The model is derived by solving Poisson's equation analytically and is used to predict the threshold voltage of MOSFETs with fully recessed oxide isolation (the trench structure). Coupling was observed between the short-channel effect and the inverse-narrow-width effect. The coupling results from the mutual modulation of the depletion depth and is used to extend the analytical inverse narrow-width model to small-geometry devices. The model is compared with experimental data obtained from the literature as well as with the three-dimensional simulator. Satisfactory agreement for channel lengths down to 1. 5 mu m and channel widths down to 1 mu m has been obtained.