A method of forming a backside illuminated image sensor using an SOI substrate including a handle substrate, an insulator formed on the handle substrate, and a semiconductor layer formed on the insulator. A sensor element is formed on the semiconductor layer, a dielectric layer is formed overlying the semiconductor layer and the sensor element; and an interconnection structure is formed in the dielectric layer to electrically connect the sensor element. A carrier substrate is forming the dielectric layer. After flipping, the handle substrate is removed to expose the insulator layer.