Thin films of silicon oxynitride (SiO_xN_y) were deposited successfully on silicon wafer substrates using electron beam physical vapor deposition (EB-PVD) technique by varying the substrate temperature (T=100–450 °C) and deposition time (t=0.5–2.5 min). The films were characterized by UV–Visible and X-ray photoelectron spectroscopy (XPS), Tally step measurement and Ellipsometry. The minimum reflectivity R=1.72% is obtained for the films deposited under the conditions of T=350 °C, t=1.5 min at λ=548 nm. Further, the characterization results revealed that the refractive index (RI) of the films increases with increase in the substrate temperature due to increase in silicon nitride content. The refractive index and the thickness of the films were found to be in the range of n=1.72–1.90 and d=40–138 nm, respectively. The values n=1.88 and d=79 nm observed corresponding to the minimum reflectivity R=1.72% satisfy the condition of near quarter wavelength single layer antireflection coating. Thus, the above films might have the tremendous potential for antireflective coating applications.