| 摘要 |
An exposure apparatus has a projection optical system for projecting a pattern of a reticle onto a wafer, a wafer stage to hold and to move the wafer, and a position detecting system to detect a position of the wafer in an optical-axis direction. The position detecting system has (i) an irradiation unit for irradiating plural lights having different wavelengths from each other onto the wafer, oblique to a surface of the wafer, the irradiation unit irradiating the plural lights onto plural places on a shot on the wafer, (ii) a detector for detecting the plural lights reflected on the plural places on the wafer, and (iii) a controller for calculating the position of the wafer in the optical-axis direction based on a detection result of the detector, the controller having a memory to store the detection, a selector to select one of the plural lights based on the stored detection result in the memory, and a calculator to calculate the position of the wafer in the optical-axis direction.
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