FIELD-EFFECT TRANSISTOR MODELING ISSUES

We consider important modeling issues accentuated by the scaling of fi eld effect transistors (FETs) into the submicron regime. High electric fields enhance non-ideal phenomena such a channel length modulation, hot-electron effects, and bias dependent mobility. In addition, improp er scaling of device dimensions and doping levels give rise to so-call ed short-channel effects resulting from a weakening of the gate contro l over the channel charge, causing threshold voltage shift, increased leakage current, and ultimately punchthrough. Our modeling approach is based on a unified charge-control model (UCCM), which allows us to co mbine accuracy and good convergence properties with physically based m odel parameters. The various effects associated high fields and short channels in FETs are contained in a description of the linear conducta nce, the saturation current, and the subthreshold current, which are c ombined in unified and continuous expressions for the drain current an d the intrinsic capacitances using UCCM.