| 摘要 |
A system for detecting the state of alignment between a reticle and a wafer of a semiconductor exposure apparatus includes a light source, a beam transfer unit, a projection lens, an alignment detector, a controller, and an alarm device. The alignment detector includes a diaphragm, and a photodiode sensor mounted on the incident side of the diaphragm. The photodiode sensor will generate a current when impinged by secondary or higher order beams, i.e. beams other than a +/-primary beam or a titled +/-primary beam. The controller receives current from the photodiode sensor and operates the alarm when the current exceeds a predetermined value.
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