| 摘要 |
PURPOSE: A wafer sensor of a cassette chamber is to sense the existence of wafers precisely during unloading them, thereby preventing the occurrence of working error, and breakage and scratch of the wafers. CONSTITUTION: A cassette chamber(CC) comprises a cassette table(6) ascending and descending therein. Many wafers are placed and stacked on the cassette chamber while being accommodated within slots of a cassette(4). A mapping sensor(12) is installed on one side wall of the cassette chamber corresponding to the parallel position of the wafer, to sense the wafer being unloaded from the lower side of the cassette. The mapping sensor has coupling type comprising both a light-transmitting part and a light-receiving part. Further, a reflecting plate(14) is provided on the other side wall of the cassette chamber opposing the mapping sensor.
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