FinFET design considerations based on 3-D simulation and analytical modeling

Design considerations of FinFET have been investigated by three-dimensional (3-D) simulation and analytical modeling in this paper. Short-channel effects (SCE) of FinFET can be reasonably controlled by reducing either silicon fin height or fin thickness. Analytical solution of 3-D Laplace's equation is employed to establish the design equations for the subthreshold behavior in the fully depleted silicon fins. Based on the 3-D analytical electrostatic potential in the subthreshold region, the threshold voltage (V-th) roll-off and the subthreshold swing (S) are estimated by considering the source barrier changes in the most leaky channel path. V-th roll-off is an exponential function of the ratio of effective channel length to drain potential decay length, which can then be expressed as a function of the fin thickness, the fin height and the gate oxide thickness. The drain-potential decay lengths of single-gate fully depleted SOI MOSFET (FDFET), double-gate MOSFET (DGFET), rectangular surrounding-gate MOSFET (SGFET), and FinFET are compared. The drain potential scaling length and V-th roll-off can be included into a universal relation for convenient comparison.