| 摘要 |
PURPOSE:To eliminate the need for particularly wide space between a ROM region and a RAM region by forming mutual pits or these pits in the ROM region and the bottom of the guide groove of the RAM region on the same plane. CONSTITUTION:A ROM region is formed within a range of a radius of 25-37mm on the main surface of a transparent substrate 1 having a diameter of 120mm, and pits P0 in width of 400-700nm and depth of 80-150nm are formed. A RAM region is shaped within a range of a radius of 37-59mm, and guide grooves Pa in width of 400-700nm and depth of 40-90nm are formed. An organic material recording layer 2, a refractive index of which is changed by the irradiation of a laser for recording, is formed on the whole region of the substrate 1. A metallic layer 3 for reflecting light is shaped onto the layer 2, and a protective layer 4 is formed onto the layer 3. The depth of the pits P0 of the ROM region is set in 130nm and the optical depth of the grooves Pa of the RAM region in 50nm at that time. According to such constitution, the standard of a compact- disc is satisfied, and wide space is unnecessitated particularly between both regions. |
