A method of forming integrated circuit (IC) chip shapes and a method and computer program product for converting an IC design to a mask, e.g., for standard cell design. Individual book/macro physical designs (layouts) are proximity corrected before unnesting and an outer proximity range is determined for each proximity corrected physical design. Shapes with a unique design (e.g., in boundary cells and unique instances of books) are tagged and the design is unnested. Only the unique shapes are proximity corrected in the unnested design, which may be used to make a mask for fabricating IC chips/wafers.