| 摘要 |
PROBLEM TO BE SOLVED: To enable stable exposure control by effecting dummy oscillation before using a laser beam generated in an oscillation mode which is realize after the switching of the oscillation modes. SOLUTION: A case is considered where the exposure of a wafer is carried out after switching a second oscillation mode to a first oscillation mode, immediately after the alignment of reticule. In the first oscillation mode used during the exposure of a wafer, an algorithm is adopted that carries out feedback control using an integrating sensor 25 and realizes a constant integrated energy. Dummy oscillation of, e.g. 50 pulses is executed immediately before the exposure of a first chip of the wafer. The dummy oscillation is similarly executed in a first control mode in the exposure of the wafer. During the dummy oscillation, a movable blind or a shutter 1f is shut so that there is no influence of the dummy oscillation at all on the wafer as an exposed object.
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