| 摘要 |
PURPOSE:To enable an alignment to be made with high accuracy even if alignment mark detection errors are caused by a method wherein the corrections are made on the basis of different correction systems corresponding to the number of detected alignment masks. CONSTITUTION:When one mark is misdetected, a mesa type deformation with least effect on alignment accuracy is disregarded but expansions and contractions whose amounts are different according to the X and Y directions, simple rotation and diamond deformation of wafer, as well as shift term are corrected. When two marks are misdetected, both of the mesa type deformation and the diamond deformation are disregarded to make the correction on an assumption that the wafer is simply rotating and isotropically expanding and contracting. Furthermore, when three marks are misdetected, on an assumption that the deformation is similar to that of a chip immediately before, the shift term only is calculated using the correction factor of the chip (block) immediately before. Through these procedures, if at least one block mark can be detected, the correction can be made properly to improve the alignment accuracy in the whole wafer.
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