Fin cross-section shape influence on short channel effects of mugfets

Abstract

Multiple-gate FETs is normally constructed on pre-etched silicon fins. These devices often present casual width variations along the silicon height; mostly caused by technological limitations of the fin definition process, due to non-ideal anisotropic etch. The resulting devices have, consequently, non-rectangular cross-sections, which can affect their electrical behavior. This work addresses the dependence of fin width non-uniformity on the occurrence of short-channel effects through comparative analysis, based on threedimensional numeric simulation of non-rectangular cross-section devices. The influence of the fin crosssection shape on electrical parameters showed to be dependent on channel length, becoming more sensible to the fin shape as the channel length is reduced, with better DC performance present on devices with bottom fin width smaller than top fin width due to the higher transconductance and lower output conductance, resulting on higher intrinsic voltage gain. For opposite fin shapes the total gate capacitance present higher values, beneficiating AC analog parameters, such as unit gain frequency.