High-Speed Deposition of New Low-Refractive-Index Dielectric Film “SiOC” for Rewritable HD DVD Media

Abstract

A low-refractive-index film plays an important role in attaining a high density of rewritable HD DVD optical recording media, for which the blue-violet laser of 405 nm wavelength incident on a 0.6-mm-thick substrate is used. We have developed a new low-refractive-index material, SiOC, for the medium, which can be sputter-deposited at much higher rates than the conventional SiO2 film. The SiOC film is formed using a SiC target with an Ar and O2 gas mixture using either a RF or DC power supply. The film exhibited similar optical constants as SiO2, and DC sputtering in particular showed very low substrate temperature rise. The resultant deposition rate per sputter power is about three times higher than the rate of deposition using a SiO2 target. The obtained thin film consists of Si, O, and C. Although the film includes a substantial amount of carbon, it showed almost the same optical characteristics as SiO2. We demonstrated that the single-layer HD DVD rewritable medium with 20 GB capacity using SiOC film had satisfactory recording characteristics. We believe that this media can be manufactured at a cost similar to that of conventional rewritable DVDs in mass production.