PRODUCTION OF OPTICAL DISK

摘要

PURPOSE:To produce an optical disk having high reliability by sticking two sheets of thermoplastic substrates directly to each other by heat, thereby suppressing infiltration of the water and oxygen in the atm. air into the substrates and preventing corrosion of a recording medium. CONSTITUTION:The information recording medium 2 is formed on the thermoplastic substrate 3 which has rugged patterns on the surface and is made of polycarbonate, etc. An underlying Si3N4 film is first formed on the medium by a sputtering method using an inline system magnetron sputtering device and using a gaseous mixture composed of Ar and N2 as a discharge gas and a sintered Si3N4 body as a target. In succession, a TbFeCoNb film is formed by using discharge gaseous Ar and an alloy target having a specific compsn. Finally, an Si3N4 film is formed under the same sputtering conditions as for the underlying film. Two sheets of such media 2 formed collectively with these three layers are stuck to each other by a thermal welding method using laser light in such a manner that the film forming sides are brought to the inner side. The infiltration of the moisture and oxygen in the atm. air into the substrates is thereby prohibited and the corrosion of the recording medium is prevented.