Image sensor pixels with conductive bias grids

Abstract

An image sensor with an array of pixels is provided. In order to achieve high image quality, it may be desirable to improve well capacity of individual pixels within the array by forming deep photodiodes in a thick substrate. When forming the array of pixels, conductive contacts may be formed in a back surface of the substrate opposing ground contacts located on a front side of the substrate. A conductive grid layer may be formed over the conductive contacts. A color filter layer may be formed over the conductive grid layer that may include a barrier grid in which color filter material is deposited. The conductive grid layer and conductive contacts may be biased to a voltage to improve the strength of electric fields in the substrate. Conductive contacts will thereby improve charge collection and electrical isolation and prevent electrical crosstalk and blooming.