A method for manufacturing the image sensor includes providing a substrate structure; forming a mask layer on the substrate structure, the mask layer having openings; depositing a metal grid material covering a surface of the mask layer and a bottom of the openings; and stripping the mask layer for removing a portion of the metal grid material on the top surface of the mask layer. The substrate structure includes: a substrate having a first surface; a plurality of pixels in the substrate; isolation structures around each of the plurality of pixels; and an anti-reflective coating on the first surface of the substrate. The openings include first openings exposing a portion of the first surface of the substrate structure above the isolation structures. A remaining portion of the metal grid material at the bottom of the openings forms metal grids.