A method includes receiving a layout of an integrated circuit (IC) device, the layout having an outer boundary and an inner boundary thereby defining a first region between the outer boundary and the inner boundary and placing a first plurality of dummy patterns in the first region, wherein the first plurality of dummy patterns is lithographically printable. The method further includes performing an Optical Proximity Correction (OPC) process, the first plurality of dummy patterns being position within the first region in such a way that prevents sub-resolution assist features from being inserted into the first region by the OPC process.