Bias sweep rate effects on quasi-static capacitance of MOS capacitors

MOS capacitance measurements are very fundamental characterization methods for MOS and FET structures. This paper discusses the effects of a finite bias sweep rate on quasi-static and high-frequency (HF) capacitance-voltage (C-V) measurements. As typically measured, a finite sweep rate causes the transition region from inversion to depletion of the quasi-static C-V curve to be shifted by several tenths of a volt along the bias voltage axis. The physical origin of this shift as well as a model to account for the effect is discussed. In order to understand quasi-static MOS C-V measurements and to extract fundamental parameter such as substrate doping density and polysilicon depletion effects from C-V measurements, these bias sweep rate effects must be understood and taken into account.