Image sensor and method of manufacturing the same

Abstract

A diffuser disposed between a microlens and a photodiode has a structure that redirects incoming light to provide favorable angles for increasing path length through the substrate, and therefore the probability of absorption, for both normally incident light and light angling toward the center of the pixel area from the periphery of the microlens. The diffuser comprises gratings formed from indentation in the semiconductor substrate that contains the photodiode. One of the gratings is disposed in each of four quadrants of an area centered beneath the microlens. Each quadrant has a midline extending radially from the center of the area. The gratings are oriented parallel to the respective midline, and perpendicular to the gratings in adjacent quadrants. The gratings may comprise trenches having V-shaped profiles.

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