Provided is an image sensor device. The image sensor device includes a substrate having a front side and a back side opposite the first side. The substrate has a pixel region and a periphery region. The image sensor device includes a plurality of radiation-sensing regions disposed in the pixel region of the substrate. Each of the radiation-sensing regions is operable to sense radiation projected toward the radiation-sensing region through the back side. The image sensor device includes a reference pixel disposed in the periphery region. The image sensor device includes an interconnect structure that is coupled to the front side of the substrate. The interconnect structure includes a plurality of interconnect layers. The image sensor device includes a film formed over the back side of the substrate. The film causes the substrate to experience a tensile stress. The image sensor device includes a radiation-blocking device disposed over the film.