Deep p-well pixel technology for CMOS back illuminated image sensors

Abstract

A new technological solution for backside illuminated CMOS imagers is proposed. The pixel area consists of an n-well/substrate photo diode and a deep p-well, which contains the APS pixel circuitry as well as additional application specific circuits. This structure was analyzed using Silvaco's ATLAS device simulator. Simulation results show that this structure provides low cross-talk, high photo response and effectively shields the pixel circuitry from the photo charges generated in the substrate. The deep p-well pixel technology allows increasing the thickness of the die up to 30 micrometers, thus improving its mechanical ruggedness following the thinning process. Such deep p-well imager structure will also be integrated into the Image Transceiver Device, which combines a front side LCOS micro display with a back-illuminated imager.