The present disclosure, in some embodiments, relates to an image sensing integrated chip. The image sensing integrated chip includes a semiconductor substrate having sidewalls defining one or more trenches on opposing sides of a region of the semiconductor substrate. One or more dielectrics are disposed within the one or more trenches. The semiconductor substrate has a plurality of flat surfaces arranged between the one or more trenches. Adjacent ones of the plurality of flat surfaces define a plurality of triangular shaped protrusions and alternative ones of the plurality of flat surfaces are substantially parallel to one another, as viewed along a cross-sectional view.