Methods for forming backside illuminated image sensors with front side metal redistribution layers

A method of forming an image sensor comprising:

• attaching a permanent carrier and a semiconductor substrate;
• forming through-silicon vias through the permanent carrier;
• thinning the semiconductor substrate that is attached to the permanent carrier in which the through-silicon vias have been formed, wherein the thinned semiconductor substrate has opposing first and second sides, wherein the permanent carrier is attached to the first side;
• and
• forming an array of photosensitive elements and associated control circuitry on the first side and forming an array of corresponding color filter elements on the second side, wherein image light reaches the photosensitive elements by passing through the color filter elements on the second side.

A system, comprising:

• a central processing unit;
• memory;
• input-output circuitry;
• and
• an imaging device, wherein the imaging device comprises:
• a semiconductor substrate comprising an array of photosensitive elements and an array of corresponding color filter elements;
• bond pads that contact the semiconductor substrate;
• a dielectric layer having openings;
• and
• a patterned metallization layer that has portions in the openings and that contacts the bond pads.