Next, {HEAD ~ the windows} are etched through the silicon nitride with {TAIL ~ CH3 F or O2 /CHF3 gases} 
are etched with
Next , { HEAD ~ the windows } are etched through the silicon nitride with { TAIL ~ CH3 F or O2 /CHF3 gases }
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL