Back-Gate Bias Dependence of the Statistical Variability of FDSOI MOSFETs With Thin BOX

The impact of back-gate bias on the statistical variability (SV) of FDSOI MOSFETs with thin buried oxide (BOX) is studied via 3-D “atomistic” drift-diffusion simulation. The impact of the principal sources of SV, i.e., random dopant fluctuations, line edge roughness, and metal gate granularity, on threshold voltage, drain-induced barrier lowering, and drive current is studied in detail. It is shown that reverse back-bias is beneficial in terms of reducing the dispersion of the off-current and the corresponding standby leakage power, whereas forward back-bias reduces the on -current variability. The correlation coefficients between relevant figures of merit and their trends against back-bias are also studied in detail, providing guidelines for the development of statistical compact models of thin-BOX FDSOI MOSFETs for low-standby-power circuit applications.