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 {HEAD ~ a plurality} of slots for receiving {TAIL ~ a second group} of semiconductor wafers 
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 { HEAD ~ a plurality } of slots for receiving { TAIL ~ a second group } of 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 HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH