Using an aqueous solution of ammonia hydroxide aqua, hydrosilicofluori
c acid and boric acid, an oxynitride film can be obtained. Using such
a liquid phase deposition method, the growth rate and the refractive i
ndex increase with the mole concentration of ammonia hydroxide aqua. A
fter thermal anealing in nitrogen ambient the thickness decreases but
the refractive index increases. This distribution of nitrogen atoms ac
cumulate at the interface of oxynitride and silicon. A model is propos
ed to explain it.