Fin Shape Impact on FinFET Leakage With Application to Multithreshold and Ultralow-Leakage FinFET Design

Abstract

FinFETs have emerged as the solution to short channel effects at the 22-nm technology node and beyond. Previously, there have been few studies on the impact of fin cross section shape on transistor leakage. We show for the first time that fin shape significantly impacts transistor leakage in bulk tri-gate nFinFETs with thin fins when the fin body doping profile is optimized to minimize leakage. We show that a triangular fin reduces leakage current by 70% over a rectangular fin with the same base fin width. We describe how fin shape can be used to implement multithreshold nFinFETs without increasing chip area consumption. We also describe how by combining triangular fins with existing gate-source/drain underlap multithreshold techniques, it is possible to design ultralow-power nFinFETs with less than 1 pA/μm leakage current while maintaining high performing I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> , threshold voltage, and subthreshold swing.