A method and system for: forming a first rectangular shape with photomask writing equipment, using a first sub-threshold dosage on a photoresist layer of a photomask substrate; forming an overlapping second rectangular shape with the photomask writing equipment using a second sub-threshold dosage on the photoresist layer, the second rectangular shape being rotated relative to the first rectangular shape to form one of: a hexagonal overlap area and an octagonal overlap area, that exposes the photoresist layer to at least a threshold dosage; and forming a photomask, based on developing the exposed photoresist layer, to provide optical transmission corresponding to the one of: the hexagonal overlap area of at least the threshold dosage and the octagonal overlap area of at least the threshold dosage, for use by a photolithography system to write any of a contact, a via, or a curvilinear shape on an integrated circuit substrate.