| 摘要 |
A method and an apparatus are proposed for aligning the pattern of an opaque mask with a previously exposed pattern on a silicon slice or a silicon wafer. Three separate optical channels are so aligned that their axes coincide with three targets on the slice. The objectives are also aligned at the same vertical distance from the slice. The optical channels then remain stationary. The slice is withdrawn a short distance and replaced by the mask, which also has three targets. The mask is then displaced in order to align the targets with the previously aligned optical axes. Once the alignment of the mask is complete, the mask and the slice are removed as a unit and taken to an exposure station.
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