| 摘要 |
In the alignment of successive masks relative to a photo-sensitive substrate in the manufacture of multi-layers respective fiducial marks on the substrate and on each mask are brought into the correct relative position for exposure of the substrate, without introducing the inaccuracy resulting from the superimposition of successive photographic images of the mask fiducial marks on the substrate. In one method the mask and substrate fiducial marks are arranged to be out of register with each other when the mask and substrate are correctly aligned, the two sets of fiducial marks being brought into register by an optical beam displacing arrangement. In alternative process the substrate fiducial marks are exposed separately from the main exposure of the remainder of the substrate before or after alignment of the substrate with the mask, or, in the case of a positive photo-resist, the substrate fiducial marks are separately masked during the exposures of the substrate after alignment thereof with each successive printing mask.
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