In some embodiments, the present disclosure relates to an image sensor device. The image sensor device includes an image sensing element disposed within a substrate. A plurality of protrusions are arranged along a first side of the substrate over the image sensing element. The plurality of protrusions respectively include a sidewall having a first segment oriented at a first angle and a second segment over the first segment. The second segment is oriented at a second angle that is larger than the first angle. One or more absorption enhancement layers are arranged over and between the plurality of protrusions. The first angle and the second angle are acute angles measured through the substrate with respect to a horizontal plane that is parallel to a second side of the substrate opposite the first side.