| 摘要 |
In an arm access position sensing method according to the present invention, optical sensors are provided in a cassette chamber. An adjusting cassette holding wafers W in the top slot and bottom slot is placed on a stage in the cassette chamber. The stage is movable. In a calibration process, the reference slot position, map position, and map thickness are calculated using optical sensors. Similarly, in a mapping process, the sampling thickness and map wafer offset value of each slot in the cassette holding the wafers W are calculated. In an arm access position sensing process, the access position of the transfer arm is calculated using the sampling thickness, map wafer offset value, reference slot position, map position, map thickness, and specific values. On the basis of the access position, the transfer arm and stage are actuated to transfer the wafer W.
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