Method for making spectrally efficient photodiode structures for CMOS color imagers

摘要

A method for making an array of photodiodes with more uniform optical spectral response for the red, green, and blue pixel cells on a CMOS color imager is achieved. After forming a field oxide on a substrate to electrically isolate device areas for CMOS circuits, an array of deep N doped wells is formed for photodiodes for the long wavelength red pixel cells. An array of P doped well regions is formed adjacent to and interlaced with the N doped wells. Shallow diffused N^+ regions are formed within the P doped wells for the shorter wavelength green and blue color pixels cells. The shallow diffused photodiodes improve the quantum efficiency (QE), and provide a color imager with improved color fidelity. An insulating layer and appropriate dye materials are deposited and patterned over the photodiodes to provide the array of color pixel cells. The N and P doped wells are also used for the supporting FET CMOS circuits to provide a cost-effective manufacturing process.