US Patent 9520435 Image sensor illuminated and connected on its back side

An image sensor including a semiconductor layer; a stack of insulating layers resting on the back side of the semiconductor layer; a conductive layer portion extending along part of the height of the stack and flush with the exposed surface of the stack; laterally-insulated conductive fingers extending through the semiconductor layer from its front side and penetrating into said layer portion; laterally-insulated conductive walls separating pixel areas, these walls extending through the semiconductor layer from its front side and having a lower height than the fingers; and an interconnection structure resting on the front side of the semiconductor layer and including vias in contact with the fingers.