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Sensing characteristics of a precision aligner using moire gratings for precision alignment sysem has been investigated. A differential moire alignment system and a modified alignment system were used. The influence of the setting accuracy of the gap length and inclination of gratings on the alignment accuracy has been studied experimentally and theoretically. Setting accuracy of the gap length less than 2.5μm is required in modified moire alignment. There is no influence of the gap length on the alignment accuracy in the differential alignment system. The inclination affects alignment accuracies in both differential and modified moire alignment systems.
Sensing characteristics of a precision aligner using moire gratings for precision alignment sysem has been investigated. A influence of the setting accuracy of the gap length and inclination of gratings on the alignment accuracy has been Viewed experimentally and theoretically. Setting accuracy of the gap length less than 2.5 μm is required in modified moire alignment. There is no influence of the gap length on the alignment accuracy in the differential alignment system. moire alignment systems.