COMPOSITE GRID STRUCTURE TO REDUCE CROSSTALK IN BACK SIDE ILLUMINATION IMAGE SENSORS

摘要

A semiconductor structure for back side illumination (BSI) pixel sensors is provided. Photodiodes are arranged within a semiconductor substrate. A metal grid overlies the semiconductor substrate and is made up of metal grid segments that surround outer perimeters of the photodiodes, respectively, such that first openings within the metal grid overlie the photodiodes, respectively. A low-n grid is made up of low-n grid segments that surround the respective outer perimeters of the photodiodes, respectively, such that second openings within the low-n grid overlie the photodiodes, respectively. Color filters are arranged in the first and second openings of the photodiodes and have a refractive index greater than a refractive index of the low-n grid. A substrate isolation grid extends into the semiconductor substrate and is made up of isolation grid segments that surround outer perimeters of the photodiodes, respectively. A method for manufacturing the BSI pixel sensors is also provided.

主权项

1. A semiconductor structure for back side illumination (BSI) pixel sensors, the semiconductor structure comprising:
a plurality of photodiodes arranged within a semiconductor substrate; a metal grid overlying the semiconductor substrate and made up of a plurality of metal grid segments that surround outer perimeters of the plurality of photodiodes, respectively, such that a plurality of first openings within the metal grid overlie the plurality of photodiodes, respectively; a low refractive index (low-n) grid made up of a plurality of low-n grid segments that surround the outer perimeters of the plurality of photodiodes, respectively, such that a plurality of second openings within the low-n grid overlie the plurality of photodiodes, respectively; color filters arranged in the first and second openings and having a refractive index greater than a refractive index of the low-n grid; and a substrate isolation grid extending into the semiconductor substrate and made up of a plurality of isolation grid segments that surround the outer perimeters of the plurality of photodiodes, respectively, wherein the substrate isolation grid is a metal or a low-n material having a refractive index less than a refractive index of the color filters.