1. A method of making a mask, the method comprising: receiving an integrated circuit (IC) design layout including a main feature; modifying the IC design layout using an optical proximity correction (OPC) technique; applying a post data process, wherein applying the post data process includes fracturing the OPC modified IC design layout into a plurality of discrete polygons; and writing the OPC modified IC design layout data onto a mask substrate using a mask writer; wherein modifying the IC design layout data using OPC includes correcting a segment belonging to an ambit of a target point and correcting a segment shared by two ambits.