Typically, {HEAD ~ the first group} of semiconductor wafers have {TAIL ~ impurities} therein which are to be removed and the second group of semiconductor wafers are to receive the impurities 
Typically , { HEAD ~ the first group } of semiconductor wafers have { TAIL ~ impurities } therein which are to be removed and the second group of semiconductor wafers are to receive the impurities
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH