The present disclosure provides methods and apparatus for reducing dark current in a backside illuminated semiconductor device. In one embodiment, a method of fabricating a semiconductor device includes providing a substrate having a frontside surface and a backside surface, and forming a plurality of sensor elements in the substrate, each of the plurality of sensor elements configured to receive light directed towards the backside surface. The method further includes forming a dielectric layer on the backside surface of the substrate, wherein the dielectric layer is formed to have a compressive stress to induce a tensile stress in the substrate. A backside illuminated semiconductor device fabricated by such a method is also disclosed.