Improved Modeling of Low-Frequency Noise in MOSFETs—Focus on Surface Roughness Effect and Saturation Region

Surface roughness scattering is known to influence the mobility at large gate voltage and, in turn, should impact the low-frequency (LF) 1/f noise in MOS devices with ultrathin gate oxide. Based on a corresponding model of mobility with a quadratic degradation factor, an accurate and simple model of LF noise with correlated mobility fluctuations is established and applied to FinFET samples. The influence of surface roughness scattering on the normalized spectral density of drain current SId/Id² and on input-referred noise SVg under strong inversion and in linear regime is analyzed. It is found that mobility-correlated fluctuations result in an increase in input gate voltage noise. In addition, a new semi-analytical 1/f noise model for MOS devices operated in a nonlinear region, based on carrier number fluctuations with correlated mobility fluctuations is developed and validated through experimental results obtained on FinFETs.