| 摘要 |
In a mark position-detecting apparatus, a rectangular reference mark is performed on a workpiece or photomask. The apparatus includes a movable table for supporting the photomask, a stationary light source for radiating light for forming a light spot on the photomask, a photodetector for detecting a change in light component transmitted through the mask, and a computer control section. The table moves forwardly and reversely in a Y-direction so that the photodetector scans two opposite edges of the reference mark in opposite directions in the Y-direction. The table is then moved forwardly and reversely in a X-direction so that the photodetector scans other two opposite mark edges. The signal detector thus produces edge position data representing the four mark edge scanned. The computer control section computes the coordinates of the mark center based on the edge position data.
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