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