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