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