| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent damage accident of a wafer or a board when the wafer is transferred, by surely detecting whether the wafer exists in a wafer cassette. SOLUTION: A wafer transferring equipment 20 is made to enter a wafer cassette in order to simultaneously vacuum-chuck and carry a plurality of wafers 1 with tweezers 21A-21E. Only one out of electromagnetic valves 24A-24E is opened, and the other electromagnetic valves are closed. Whether a vacuum- chucked wafer exists on one tweezer or not is judged with either one of vacuum sensors 23A and 24E, and practical wafer accommodation data at a predetermined position in a cassette are obtained. The above process is repeated for all tweezers. Previously stored setting wafer accommodation data are compared with practical wafer accommodation data. When both of the data do not coincide with each other, all electromagnetic valves 24A-24E are closed, an alarm is outputted, and carrying operation of the wafer transferring equipment 20 is interrupted. When both of the data coincide with each other, the wafer 1 is transferred to a boat by operating the wafer transferring equipment 20.</p> |
