Back-side illuminated image sensor

Image sensors and methods of manufacturing image sensors are provided. One such method includes forming a structure that includes a semiconductor layer extending from a front side to a back side, and a capacitive insulation wall extending through the semiconductor layer. The capacitive insulation wall includes first and second insulating walls separated by a region of a conductor or a semiconductor material. Portions of the semiconductor layer and the region of the conductor or semiconductor material are selectively etched, and the first and second insulating walls have portions protruding outwardly beyond a back side of the semiconductor layer and of the region of the conductor or semiconductor material. A dielectric passivation layer is deposited on the back side of the structure, and portions of the dielectric passivation layer are locally removed on a back side of the protruding portions of the first and second insulating walls.