An image sensor device including a semiconductor substrate that includes an array region and a black level correction region. The array region contains a plurality of radiation-sensitive pixels. The black level correction region contains one or more reference pixels. The substrate has a front side and a back side. The image sensor device includes a first compressively-stressed layer formed on the back side of the substrate. The first compressively-stressed layer contains silicon oxide, and is negatively charged. The second compressively-stressed layer contains silicon nitride, and is negatively charged. A metal shield is formed over at least a portion of the black level correction region. The image sensor device includes a third compressively-stressed layer formed on the metal shield and the second compressively-stressed layer. The third compressively-stressed layer contains silicon oxide. A sidewall of the metal shield is protected by the third compressively-stressed layer.