Characterization of silicon oxynitride films deposited by a high-power impulse magnetron sputtering deposition technique

In this research, silicon oxynitride films were prepared by high-power impulse magnetron sputtering with 45/955 pulse on/off time. The extinction coefficient was smaller than 1 × 10⁻³ from 250 to 700 nm after introducing 2.2 sccm O₂ gas at room temperature. A three-layer of AlF₃/SiO_xN_y AR coating was designed and fabricated on double-sided quartz, and a high transmittance of 99.2% was attained at 248 nm. The silicon oxynitride films deposited at 350^◦C had the better mechanical and optical properties in the visible range. The hardness of all deposited films was greater than 19 GPa, and the greatest hardness could reach to 29.8 GPa. A film structure of six-layer transparent hard coating/glass/four-layer AR coating was designed and deposited. Its average transmittance was 96.0% in the visible range, while its hardness was 21 GPa and its surface roughness was 0.23 nm.