In this paper, the first systematic study of uniaxial stress effects on mobility (mu)/on-current (Ion) enhancement and gate current (Ig) reduction in FinFETs is described. We demonstrate for the first time that Ig of (110) side-surface pFinFETs is largely reduced by longitudinal compressive stress due to out-of-plane mass increase. (110) n/pFinFETs are superior to (100) FinFETs in terms of higher mu/Ion enhancement ratio by longitudinal strain and comparable/higher short-channel Idsat. Three-dimensional stress design in FinFETs including transverse and vertical stresses is proposed based on the understanding of stress effects beyond bulk piezoresistance.