Effect of body bias and temperature on low-frequency noise in 40-nm nMOSFETs

This study investigated the effects of temperature and body bias on drain current flicker noise (1/f) in 40-nm nMOSFETs. The 1/f noise is attributable to the charge number fluctuation correlating with the mobility fluctuation. At 300 K, as the depletion width was decreased, 1/f noise decreased with the body bias from − 0.5 to + 0.5 V in the weak inversion; conversely, 1/f noise was independent of the body bias because of the neglected depletion charge capacitance in the strong inversion. When the temperature was below 150 K, 1/f noise increased when the drain voltage was low because of the Fermi level toward the band edge, which has a higher trap density and corresponds to the inverse square of the subthreshold swing. However, when the drain voltage was high, 1/f noise was dominated by the mobility fluctuation because a wider strong inversion region at 150 K resulted in a lower 1/f noise and insignificant body effect. The analysis of this behavior in 40-nm devices may assist in determining the optimal device fabrication methods and circuit design.