The wafer transfer device has a first unit with a plurality of first slots for receiving a first group of semiconductor wafers and a second unit with a plurality of slots for receiving {HEAD ~ a second group} of {TAIL ~ semiconductor wafers} 
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The wafer transfer device has a first unit with a plurality of first slots for receiving a first group of semiconductor wafers and a second unit with a plurality of slots for receiving { HEAD ~ a second group } of { TAIL ~ semiconductor wafers }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL