A method of making a backside illuminated sensor is provided. A substrate is provided and a high energy ion implantation is performed over the substrate to implant a first doped region. A layer is formed over the substrate and a self-align high energy ion implantation is performed over the substrate to implant a second doped region over the first doped region. The combined thickness of the first and second doped region is greater than 50 percent of thickness of the substrate and the distance between back surface of the substrate and the first and second doped regions is less than 50 percent of thickness of the substrate. In this way, an enlarged light sensing region is formed through which electrons generated from back surface of the surface may easily reach the pixel.