We have studied the impact of thermal contact resistance (TCR) ( Rth ) and within-chip ambient temperature ( TA ) on the device self-heating effect (SHE) and its effect on transient and steady-state performance of Si 3-Fin FinFET-based CMOS inverter (from N-14 to N-7 technologies) using coupled hydrodynamic-thermodynamic (HD-TH) mixed-mode simulations. The effect of the load capacitance ( CL ) on device lattice temperature ( TL ) and its impact on propagation delay ( tpd ) of the targeted CMOS inverter circuit are analyzed. The impact of technology scaling on SHE of inverter and its effect on circuit performance is also studied. We investigated the SHE in the 3-Fin FinFET-based ring oscillator (RO) and estimated the stage delay and frequency of oscillations. Our simulation results revealed that within-chip TA and Rth of gate, source, and drain ( Rth,GSD ) have significant effect on the logic circuit performance in terms of degradation of noise margin (NM), inverter gain ( gmax), and increase in tpd due to SHE from N-14 to N-7 technologies. © 1963-2012 IEEE.