Patent ID: 7982177

Claim:
A frontside illuminated image sensor, comprising: a doped silicon substrate layer having a complex-shaped surface; a stack of metal layers disposed over the doped silicon substrate layer; a silicon layer disposed between the doped silicon substrate layer and the stack of metal layers, the silicon layer having a light incident side facing the stack of metal layers and an opposite side facing the doped silicon substrate layer, the silicon layer disposed over the complex-shaped surface of the doped silicon substrate layer and being a single layer that is distinct from the doped silicon substrate layer; a plurality of photosensitive regions disposed within the silicon layer; and reflectors disposed at an interface between the doped silicon substrate layer and the silicon layer at the complex-shaped surface, wherein at least one side of the reflector layers conforms to the complex-shaped surface of the doped silicon substrate layer, wherein the reflectors are disposed on the opposite side of the silicon layer as the light incident side, wherein the complex-shaped surface is oriented such that light incident on the complex-shaped surface of the reflectors after passing through the stack of metal layers and the photosensitive regions is reflected back towards the photosensitive regions.