A new interface roughness scattering model is developed using exponential autocovariance functions.The electron mobility in 6H-SiC inversion layers is studied by single-electron Monte Carlo approach that takes into account the size quantization and the main scattering mechanisms in SiC inversion layers.The simulation results show that the electron mobility calculated using the exponential model presented in this paper are in good agreement with the experimental data. Interface roughness scattering is shown to play a strong role in the high effective transverse field.The electron mobility falls as the temperature increases.The roughness scattering under higher effective fields is reduced significantly by screening effects.