Extraction of series resistance using physical mobility and current models for MOSFETs

The series resistance at source and drain junctions is evaluated using a surface potential based current vs. gate bias (I–VG) model. To achieve ultimate accuracy and efficiency, a I0–VG model is newly advised for spreadsheet analysis. The electric field dependent mobility model in the literature is modified for easier graphical comparison with the conventional VT-based expression. Using NMOSFETs with different gate length, the exponent for the surface phonon scattering is evaluated to be ≈0.61 for the electric field based expression, and is close to unity in case of the VT-based expression. A smoothly non-linear series resistance vs. gate length relation is successfully confirmed, and the rough agreement with the conventional analysis is discussed to be reasonable.