PURPOSE: To improve repeatability characteristics by a method wherein, in order to obtain an optical recording medium by providing a recording layer which is denatured by absorbing a light and dielectric layers provided closely to it on a transparent substrate, a heat diffusion layer which is transparent and has a heat diffusion coefficient larger than a dielectric foundation layer is provided between the transparent substrate on a light incidence side and the foundation layer.
CONSTITUTION: An optical disc is composed of a PC substrate 1, a foundation dielectric protective layer 2 made of 80 at% Zn and 20 at% SiO2, a recording layer 3 made of Ge2Sb2Te5, a dielectric protective layer 4 made of same material as the protective layer 2 and a metal reflection layer 5 which are built up in this order from a light incidence side and a sealing layer 6 is provided on the side opposite to the light incidence side. In addition to this composition, a heat diffusion layer 7 which is transparent and is made of material having a heat diffusion coefficient larger than the protective layer 2 is inserted between the substrate 1 and the layer 2. The layer 7 is composed of an AlN sputtering film and a diamond film or a diamond coarbon film having a light heat diffusion coefficient is used. With this constitution, a writing/erasing sensitivity can be improved and, further, repeatability characteristics are also improved.
YAMAZAKI HIRONORI
FUJIMORI SUSUMU
SUGIYAMA YASUYUKI
