This paper investigates the effect of process variations on unity gain frequency (ft) in 30 nm gate length FinFET by performing extensive 3D TCAD simulations. Sensitivity of ft on different geometrical parameters, channel doping, source/drain doping and gate electrode work function are studied. It is found that ft is more sensitive to gate length, underlap, gate oxide thickness, source/drain doping and corner radius, and less sensitive to source/drain length, source/drain cross-sectional area, hard-mask height, fin-taper and work function variations. © 2011 IEEE.