Effect of sputtering pressure on the structure and properties of SiO 2 films prepared by magnetron sputtering

The effects of sputtering pressure on the O/Si ratio, microstructure, surface morphology and optical properties within 300–1100 nm of SiO 2 film via radio frequency magnetron sputtering were investigated. The results showed that the molar ratio of O/Si in the film increased from 1.96 to 2.03, from silicon rich to oxygen rich, with the sputtering pressure increase from 0.3 to 1.3 Pa. The SiO 2 films deposited at different pressure were all amorphous. There were many ditches with a length of about 50 nm on the surface of the film deposited at lower pressure. The increase of sputtering pressure could reduce the number of ditches, and make the surface denser and more uniform. The refractive index increased first, then decreased and finally increased with the increase of sputtering pressure, and the maximum and minimum values were obtained at 0.7 and 1.1 Pa, respectively. The change of absorptivity was approximately the same as that of the refractive index, while the change of the average transmittance of coated quartz glass was exactly the opposite of refractive index. The minimum value of the average transmittance 92.6% and the maximum value 93.1% were obtained at 0.7 and 1.1 Pa, respectively.