| 摘要 |
It is important to assess and reduce errors that arise in mask correction techniques such as optical proximity correction. A preliminary mask is obtained using an OPC model. An etched wafer is created from the preliminary mask using lithography, and first and second critical dimensions (CD) are measured on the wafer. An edge placement error (EPE) is determined that corresponds to a difference between a measured value and a desired value of the second CD. These steps are repeated for a plurality of different values of the first CD, and for each of the values, the measured value of the second CD is correlated with its corresponding value on the mask as predicted by the OPC model. Delta difference DeltaCD is obtained between the difference of the mask CDs calculated by interpolation of wafer CD measurements and by OPC model predictions and is transformed into an OPC model error.
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