Analytical parameter extraction for small-signal equivalent circuit of 3D FinFET into Sub-THz range

This paper presents an improved radio frequency small-signal equivalent circuit model of deep nanometer fin field-effect transistors (FinFETs) with a 3-D device simulator. A novel parameter extraction method is proposed based on the nonlinear rational function fitting. The extrinsic gate-to-drain/source capacitances, source/drain resistances, and substrate elements are first obtained from Y-parameters under the off state. Then, the intrinsic electrical parameters are analytically determined after multibias Y-parameters fitting under the forward active mode. The model and proposed extraction method are verified with the device-simulation data of a series of sized FinFETs up to 300 GHz. Excellent agreement is obtained between the simulated and modeled S-parameters, and the calculated modeling error is under 3.74% in the whole frequency range among multibias points. Besides, the bias and geometry dependence of the small-signal parameters are discussed.