Image sensor and manufacturing method thereof

A semiconductor device, comprising:

• a substrate having a first side and a second side opposite to the first side;
• an interconnect, located on the first side;
• a plurality of first isolations located in the substrate at the first side and electrically isolated from the interconnect;
• a photodiode array, disposed in the substrate within an active region of the substrate and electrically connected to the interconnect;
• an isolation structure, extending from the second side of the substrate to a position in the substrate within the active region, wherein the photodiode array is surrounded by and spaced apart from the isolation structure, and the isolation structure comprises a conductive grid;
• and
• a plurality of conductive structures, disposed in the substrate within a peripheral region of the substrate and electrically connected to the interconnect, wherein the conductive grid is electrically connected to the interconnect through the conductive structures and is electrically isolated from the photodiode array,
• wherein the conductive structures penetrate through the first isolations for electrically connecting to the interconnect.

An image sensor, comprising:

• a pixel in a substrate, the pixel comprising a photosensitive region and a circuitry region next to the photosensitive region;
• a plurality of doped isolations disposed in the substrate at a first side and an interconnect disposed over the first side of the substrate;
• an isolation structure disposed at a second side of the substrate opposite to the first side, the isolation structure comprising a first dielectric structure and a conductive grid on the first dielectric structure filling in a grid mesh cavity over the circuitry region and surrounding the photosensitive region;
• and
• a plurality of conductive structures disposed next to the isolation structure in a plurality of openings at the second side of the substrate, wherein the conductive structures are electrically connected to the conductive grid of the isolation structure, and the isolation structure is electrically isolated from the pixel,
• wherein the conductive structures are in contact with the doped isolations for electrically connecting the interconnect and the conductive grid through the doped isolations.