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Advanced lithography optical proximity correction (OPC) techniques rely on accurately tuned process models. Although through-process OPC models are being used for critical layers at the 65-nm node, typically an initial model is created at a single optimized process setting. Such 'best condition' models often produce process-window limiting structures that can impact yield. A new methodology is presented for identifying misprinted structures during the qualification of a new photomask and optimizing the process model based on those structures. Instead of the traditional approach which employs repeater analysis, the new technique bins the process-limiting structures according to their design. This method enables efficient data reduction and identification of a new feature set for lithography process model tuning. Index Terms--Defect inspection, design based binning, lithography, model tuning, optical proximity correction (OPC), RET.