Patent ID: 8895349

Claim:
A method of forming a backside illuminated image sensor, the method comprising: forming a sensor element overlying a semiconductor substrate, the semiconductor substrate having a front side and a backside, the sensor element being formed to overlie the front side of the semiconductor substrate, the sensor element being at least partially formed by: forming a transistor structure including a gate, a spacer, a source and a drain; and forming a light sensing region disposed in the source, the light sensing region having a dopant type opposite a dopant type of the source, the light sensing region being formed to extend beneath the spacer of the transistor structure; forming a capacitor overlying the sensor element, the capacitor being formed to overlie an entirety of the light sensing region in one direction and be electrically connected to the drain; forming a plurality of dielectric layers overlying the sensor element; and forming an interconnection structure in the plurality of dielectric layers, wherein at least two metal layers of the interconnection structure and at least one of the plurality of dielectric layers between the at least two metal layers form the capacitor and an additional metal layer of the interconnection structure is electrically connected between the sensor element and the capacitor.