| CPC G03F 7/70525 (2013.01) [G03F 7/70033 (2013.01)] | 20 Claims |

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1. A method of tool matching, comprising:
determining aberration maps of two or more optical systems of two or more scanner tools;
adjusting one or more Zernike coefficients of the two or more optical systems, based on the determined aberration maps of the two or more optical systems, to minimize critical dimension (CD) variations between the two or more scanner tools;
generating a photoresist pattern by projecting a first layout pattern on a respective substrate by an optical system of each one of the two or more scanner tools;
determining if the CD variations in a first region of the photoresist patterns of the respective substrates are within a threshold value; and
repeating the adjusting, the generating, and the determining if the CD variations are not within the threshold value in the first region.
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