A method is provided for making an integrated circuit (IC). Cell (200) representing a layout of a set of features, is divided into at least a first region (250) and a second region (240). Optical Proximity Correction (OPC) is carried out on at least the first region of cell (200). One or more instances of cell (200) are located to define IC prior to carrying out final OPC optimisation on the second regions (240) of each cell (200) in the defined IC.
