| 摘要 |
PURPOSE:To swiftly detect a mark position, by detecting the mark position while a stage being consecutively moved at a maximum speed satisfying three specific conditions. CONSTITUTION:While a mark position being detected, a stage is consecutively moved at a speed, which is below a stage-allowable one. The distance, in which the mark is moved while the position of one mark being detected, is below the length between marks in the stage-moving direction. The distance, in which the mark is moved while the beams being scanned to detect the position of one mark, is below the length of beam deflection in the stage-moving direction. The maximum value of the stage-moving speed satisfying these three conditions is computed in a stage-speed operational circuit 36, to be supplied to a stage controlling circuit 34, so that the stage 15 is consecutively moved. Hence, the mark position can be determined at a high speed.
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