An advanced FinFET design is identified to improve both variation and minimum operation voltage $(V_{\text{min}})$ in various temperature and supply voltage $(V_{\text{dd}})$ ranges, using sub-10 nm FinFET transistors. Through a clarification of each electrical parameter's impact on both variation and operation voltage, a suitable FinFET design is successfully demonstrated to reduce $I_{\text{eff}}$ variation by 0.4x, as well as Idoff variation by 0.8x in various $V_{\text{dd}}$ ranges. This paper also provides Tr. design to improve $V_{\text{min}}$ by 35 mV with the switching energy 0.87x reduction.