The mass flow controllers 74 and 76 control {HEAD ~ the flow rates} of {TAIL ~ the silane phosphine mixture} 
of
The mass flow controllers 74 and 76 control { HEAD ~ the flow rates } of { TAIL ~ the silane phosphine mixture }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL