| 摘要 |
A step and scan exposure system projects a reticle image onto a semiconductor wafer mounted on a semiconductor wafer stage by a projection optical system in a slit scan scheme, focusing illumination light on the semiconductor wafer to form a plurality of focus sense areas arranged in a direction perpendicular to a scanning direction, receiving reflected illumination light by a plurality of photodetectors, and controlling the wafer stage by the signals from the plurality of photodetectors. In one embodiment, the signals from the plurality of photodetectors are selected, for controlling the wafer stage, corresponding to designated regions for focusing on the semiconductor wafer.
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