An Improved Model for the Full Well Capacity in Pinned Photodiode CMOS Image Sensors

Abstract

An improved analytical model for quantifying the full well capacity in pinned photodiode (PPD) CMOS image sensors is proposed. The model captures the characteristics of the realistic technology-induced vertical doping nonuniformity in photon sensing N-type area of the PPD structure and the voltage dependency of the PPD capacitance, respectively, both of which were neglected in the existing works. Excellent agreement between measured and predicted data shows that the proposed model fits a wider range of technology conditions for a wider spectra responding compared to the up-to-date reported model.