| 摘要 |
PURPOSE:To enable a highly accurate detection of the position even when a reticle window is unclear due to an insufficient quantity of light from a wafer, by providing a reflecting plate near the wafer and by shifting the plate to the center of a reducing lense with a step feeding mechanism. CONSTITUTION:A reflecting plate 11 is disposed near a wafer 1, and is shifted to the center of a reducing lense 3 with a step feeding mechanism, while the position thereof is measured by a position detecting machanism. The outputs of the X and Y detectors at this moment present clear waveforms of the reticle windows 10, thereby La and Lb can be easily detected. Then the wafer 1 is shifted to the center of the reducing lense 3 to detect the target pattern. The outputs of the X and Y detectors at this moment enable detection of Lc and Ld. Thus, a difference between the both patterns can be obtained. |
