A backside illuminated sensor includes a semiconductor substrate having a front surface and a back surface, and a plurality of pixels formed on the front surface of the semiconductor substrate. The sensor further includes a plurality of absorption depths formed within the back surface of the semiconductor substrate. Each of the plurality of absorption depths is arranged according to each of the plurality of pixels. A method for forming a backside illuminated includes providing a semiconductor substrate having a front surface and a back surface and forming a first, second, and third pixel on the front surface of the semiconductor substrate. The method further includes forming a first, second, and third thickness within the back surface of the semiconductor substrate, wherein the first, second, and third thickness lies beneath the first, second, and third pixel, respectively.