| 摘要 |
PURPOSE:To preferably align a pair of masks without necessity of separate marks for bright and dark visual fields by employing alignment marks of the pair of right and left masks symmetrical with respect to the crossing point of a pair of CCD arrays perpendicularly secured. CONSTITUTION:Alignment marks 21a, 21b of masks used for 1:1 symmetrical projection automatic aligner are formed symmetrically with respect to the crossing points of a pair of perpendicular CCD arrays 22a, 22b. The marks 21a, 21b are separated in the bright visual field of a wafer, and detected by marks 21a1-21a4, 21b1-21b4 of the portions except 21a0, 21b0, and detected only by the marks 21a0, 21b0 inside the profiles of the marks 21a, 21b of the pair of the masks by superposing the marks 21a, 21b on the wafer in the dark visual field for the alignment. |
