| 摘要 |
PURPOSE:To prevent the warpage of a transparent plastic board by controlling the conditions of the plasma etching of the surface of the transparent plastic board so that the product of the power of etching and an etching time is kept within a specific range. CONSTITUTION:A silicon nitride film 1b is formed onto a transparent plastic board 2 through reactive sputtering. A TbFeCo film as a recording layer 3 is formed onto the film 1b. The surface and the rear of the board are turned over, and the surface on the side reverse to the layer 3 is plasma-etched. The surface of the board 2 is plasma-etched under conditions, in which the product of power density per the unit surface of an etching surface and an etching time is kept at a value from 0.02 to 1.00 on these plasma etching. A silicon nitride film 1a as a transparent thin-film layer is shaped in the same manner as the film 1b is formed. Accordingly, an optical disc having excellent adhesion and the transparent thin-film can be acquired. |
