A method of forming of an image sensor device includes a patterned hardmask layer is formed over a substrate. The patterned hard mask layer has a plurality of first openings in a periphery region, and a plurality of second openings in a pixel region. A first patterned mask layer is formed over the pixel region to expose the periphery region. A plurality of first trenches is etched into the substrate in the periphery region. Each first trench, each first opening and each second opening are filled with a dielectric material. A second patterned mask layer is formed over the periphery region to expose the pixel region. The dielectric material in each second opening over the pixel region is removed. A plurality of dopants is implanted through each second opening to form various doped isolation features in the pixel region.