| 摘要 |
PURPOSE:To improve the corrosion resistance of a metallic material used in a layer incorporating a magnetic medium and to obtain the optical disk having high reliability by incorporating nitrogen or oxygen or both thereof into the metallic material. CONSTITUTION:The diffusion of the oxygen into the metallic layer is suppressed and the inactivation to local corrosion, such as pitting and particularly corrosive ions is attained by incorporating the nitrogen into the metallic layer at the time of forming the metallic film 5 to be provided on the uppermost layer of the optical disk and, therefore, the metallic layer has high corrosion resistance and acts as a protective film. The metallic protective film 5 on the extreme surface of the disk having the structure such as, for example, a substrate 1/a 1st dielectric film 2/a recording film 3/a 2nd dielectric film 4/the metallic protective film 5 in which the above-mentioned film is used as the protective film has the high corrosion resistance and, therefore, the three layers 2 to 4 under the film 5 are not subjected to the corrosion at all. The resistance to erosion and oxidation is improved in this way and since the corrosion resistance to the local corrosion as represented by pitting is improved, the reliability of the disk is improved. |
