To overcome some of the restrictions associated with the photographic process, new methods for Resolution Enhancement Techniques (RET) are being constantly explored and applied. An essential step in any RET method is Optical Proximity Correction (OPC). In this process the edges of the target desired shapes are manipulated to compensate for light diffraction effects and result in shapes on wafer as close as possible to the desired shapes. Manipulation of the shapes is always restricted by Mask Rules Checks (MRCs). The MRCs are the rules that assure that the pattern coming out of OPC can be printed on the mask without any catastrophic faults. Essential as they are, MRCs also place constrains on the solutions explored by the OPC algorithms.

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