Direct evaluation of DC characteristic variability in FinFET SRAM Cell for 32 nm node and beyond

V_t variability in FinFET SRAM is evaluated for the first time by direct measurement of the cell transistors down to 25 nm gate length. By taking the V, mismatch between Pull-Down transistors (PD) or between PD & Pass Gate transistor (PG), the dependence of V, variability on the cell transistor layout and channel impurity concentration was clearly observed. Read / Write margins in FinFET SRAM cell are also investigated by measuring both N-curves and their variability. The results suggest that FinFET is still a promising candidate for SRAM applications even in 32 nm node and beyond, if the appropriate cell design is applied.