At the same time, {HEAD ~ a quantity} of oxygen is flowed into the reactor tube so that the oxygen also contacts the silicon wafer and intermixes and reacts with the silane, phosphine and boron trichloride gases to form layers of borophosphosilicate glass on {TAIL ~ the silicon wafer} 
At the same time , { HEAD ~ a quantity } of oxygen is flowed into the reactor tube so that the oxygen also contacts the silicon wafer and intermixes and reacts with the silane , phosphine and boron trichloride gases to form layers of borophosphosilicate glass on { TAIL ~ the silicon wafer }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL