| 摘要 |
PROBLEM TO BE SOLVED: To provide an aligner for ensuring accurate focusing operation of a multi-point AF system, and for operation highly accurate exposure, even when a position at which the strictest focusing is required in the exposure visual field of a projection optical system is separated from the measuring point of the multi-point AF system. SOLUTION: A planar reference board 71 for measuring a Z-directional position of the virtual reference face of a focusing mechanism in a multi-point oblique incident system is provided on a wafer stage. The planar reference board 71 is provided with an emissive opening mark 72, and a focal point correction mechanism for correcting the reference face is optically connected with the opening mark 72. The image of the opening mark 72 which is returned after being reflected on a reticule is detected by the focal point correcting mechanism, and the Z-directional position of the optimal image formation face is measured, and the correction of the reference face is conducted, based on the measured result. Thus, even if the opening mark 72 is arranged at an arbitrary position within a projection visual field IF of the projection optical system, a first measuring point AFij of the focusing mechanism is made positively to be present on the surface of the planar reference board 71.
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