{TAIL ~ The windows} are etched through the glass layer with {HEAD ~ BCl2 or CHF3 /CF4 etch gases} 
{ TAIL ~ The windows } are etched through the glass layer with { HEAD ~ BCl2 or CHF3 /CF4 etch gases }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD