Abstract: A photomask structure including a first layout pattern and a second layout pattern is provided. The second layout pattern is located on one side of the first layout pattern. The first layout pattern and the second layout pattern are separated from each other. The first layout pattern has a first edge and a second edge opposite to each other. The second layout pattern has a third edge and a fourth edge opposite to each other. The third edge of the second layout pattern is adjacent to the first edge of the first layout pattern. The second layout pattern includes a first extension portion exceeding an end of the first layout pattern. The first extension portion includes a first protruding portion protruding from the third edge of the second layout pattern. The first protruding portion exceeds the first edge of the first layout pattern.

Abstract: An optical proximity correction (OPC) device and method is provided. The OPC device includes an analysis unit, a reverse pattern addition unit, a first OPC unit, a second OPC unit and an output unit. The analysis unit is configured to analyze a defect pattern from a photomask layout. The reverse pattern addition unit is configured to provide a reverse pattern within the defect pattern. The first OPC unit is configured to perform a first OPC procedure on whole of the photomask layout. The second OPC unit is configured to perform a second OPC procedure on the defect pattern of the photomask layout to enhance an exposure tolerance window. The output unit is configured to output the photomask layout which is corrected.