A photosensitive device having at least an insulator layer including a plurality of photoreceiving regions disposed on a substrate. A plurality of conductive patterns is disposed on the insulator layer without covering the photoreceiving regions. A flattened dielectric layer is disposed on the conductive patterns and the insulator layer, wherein a surface of the dielectric layer is higher than a surface of the conductive patterns in a range between 2000 Å to 4000 Å.