| 摘要 |
PROBLEM TO BE SOLVED: To minimize a movement region of moving points formed in the periphery of a stage by executing a leveling operation with the center of a specified region of a wafer to be exposed as a reference. SOLUTION: When a wafer 30 is mounted above on a stage 32, light emitted by a light-emitting diode 42 is transformed into parallel light by means of a collimator lens 44 and then is incident on an exposure region of the wafer 30. Light reflected on the region of the wafer converges on a four-split optical sensor 48 through the collimator lens 46. The position of a focus 51 formed on the four-split optical sensor 48 is detected, and when the exposure face of the wafer does not cross at right angles with an optical axis of the optical system and the focus 51 is formed on the side of either one of sensing faces 52a-52d, moving points 34, 36, 38, 40 of the stage 32 are moved upward or downward, so that the gradient of the exposure face of the wafer crosses at right angles to the optical axis of the optical system and is leveled. |
