Protective films prepared by the electron cyclotron resonance plasma chemical vapor deposition technique for phase-change-type optical disks

Hydrogenated amorphous silicon carbide (a-SiC:H) films are prepared by the electron cyclotron resonance plasma chemical vapor deposition (ECR PCVD) technique. The films are, for the first time, applied as protective layers for phase-change-type optical disks. Three kinds of films with different hydrogen contents are investigated to improve writing sensitivity. The writing laser power required to obtain a sufficient carrier-to-noise ratio is 11 mW at a 10 m/s linear velocity, which corresponds to a 30% power reduction compared to conventional rf-sputtered ZnS protective layers. This is attributed to the decreased thermal conductivity of these protective layers. The hydrogen in the films is confirmed to be thermally stable.