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