| 摘要 |
When a mask is irradiated obliquely with light from a lighting system, the light reflected from the mask is projected onto a wafer through a projection optical system, and the pattern of the mask is transferred to the wafer. If the magnification of the projection optical system changes because of a vertical movement of the mask, a control unit detects the projection position of the mask pattern image on a stage by an aerial image sensor and also detects a mark on the aerial image sensor by a mark detector so as to determine the baseline of the mark detector. Thus, the positional shift of the projection position of the mask pattern image on the wafer due to the change in magnification is corrected to sufficiently restrict or prevent alignment inaccuracy associated with the change in magnification.
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