Design and Evaluation of Filterless RGB Sensor on Standard CMOS Process

Abstract

In this study, a color detection phenomenon that does not utilize color filters is evaluated via the standard CMOS process. The device comprises multiple pn-junctions stacked in the depth direction, which enable division of the light responses by different light absorptions with respect to wavelength. To eliminate the color filters, we use rectifiers to cut the reverse currents corresponding to the long-wavelength infrared (Ir) regions. Numerical simulations predict the dynamic range of the sensor as 160 dB after removal of the filters that can decrease this value. Applications based on the Internet of Things can be realized via mass production at low cost by eliminating the additional processes required to form the conventional color filters in front of the sensor. We evaluate the proposed device by both numerical simulation and experiment as well as clarify that the sensing phenomenon requires sufficient PWell thickness to separate the depletion regions for successful operation. The appropriate process parameters for the CMOS process are revealed, providing useful information for testing under a wide range of process conditions.