| 摘要 |
A 1:1 projection aligner includes a first optical system for irradiating a light beam, emitted from a light source, on a wafer through a mask; and a second optical system for irradiating a light beam, emitted from the same light source, as that of the first optical system for auto-alignment of the wafer. The aligner further includes a timer for measuring an elapsed time and outputting a signal after a specified time has elapsed, first and second shutters for shielding light paths of light beams from the first and second optical systems, and drive units for driving the shutters on the basis of a signal from the timer. In the case of a failure of the auto-alignment operation, the shutters are closed for preventing the wafer from being irradiated with a light beam for a long time, thereby preventing generation of a defect such as unevenness of exposure. An alarm is also outputted for informing an operator of the failure of the auto-alignment.
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