{HEAD ~ A thickness} of {TAIL ~ about 700 to 900 Å} of a silicon nitride film is suitable for a refractive index of about 1.9 to 2.0 
of
{ HEAD ~ A thickness } of { TAIL ~ about 700 to 900 Å } of a silicon nitride film is suitable for a refractive index of about 1.9 to 2.0
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH