| 摘要 |
PURPOSE:To always enable an accurate mark detection even if the mark for alignment is formed on the back of a sensitive substrate by mutual calibration by providing a focal point detection system for the surface of the sensitive substrate and a focal point adjusting system for the back of the sensitive substrate. CONSTITUTION:The focal point of an alignment system 20 which observes the back of a wafer W is adjusted automatically according to the movement of the a Z-stage 9 adjusted by the focussing operation for the surface of the wafer W which is to be exposed. Accordingly, detecting the focal point according to the picture signal by the alignment system 20 can be omitted. This can improve the precision of alignment, can make matching between alignment systems easy and an aligner which has an alignment unit which has the highly free selection of a mark position can be obtained.
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