| 摘要 |
In an apparatus which positions an average plane thereof parallel to a best focus plane of a projection optical system even if there is unevenness on a wafer, a leveling stage is tilted on the basis of detection signal from an auto-leveling system and a surface of a shot area on a wafer is positioned in a predetermined tilt position relative to a focus plane of the projection optical system. While such a position being kept unchanged, a deviation between the focus plane of the projection optical system and the surface of the shot area is detected at each of multi-points. Within the shot area, by the use of auto-focus system, an amount of relative tilt between an average plane of the shot area obtained from plural deviations and the focus plane of the projection optical system is calculated, and by the use of thus calculated amount of tilt and the detection signal of auto-leveling system, the focus plane of the projection optical system is positioned in parallel with the average plane of the shot area.
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