Next, a layer of BPSG is deposited and reflowed in {HEAD ~ a steam atmosphere} to produce {TAIL ~ an approximately planar surface} 
to produce
Next , a layer of BPSG is deposited and reflowed in { HEAD ~ a steam atmosphere } to produce { TAIL ~ an approximately planar surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL