Differential Body-Factor Technique for Characterization of Interface Traps in MOSFETs

A differential body-factor technique (DBT) is proposed for characterization of interface traps in MOSFETs employing the differential body factor dm/dV_GS instead of the subthreshold slope or the body factor itself. The DBT is independent of the threshold voltage variation and advantageous to apply to MOSFETs with strong nonlinearity in the subthreshold slope caused by a nonuniform distribution of traps over the band gap. We applied the DBT to n- and p-MOSFETs with W/L = 5/0.13, 5/0.18, and 2/0.13μm/μm on the same wafer and obtained identical results. Extracted interface trap density ranges D_it = 10¹⁰-10¹¹ cm^-2eV^-1 with a U-shaped distribution over the band gap.