OPTICAL INFORMATION MEDIUM AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide an optical information medium having excellent recording and erasing characteristics and overwriting characteristics by forming at least one of an undercoating layer and overocating layer which are dielectric layers to protect a recording layer of a layer which is a mixture composed of tantalum oxide and zinc sulfide and contains a nitrogen component or both of the nitrogen component and an oxygen component. SOLUTION: The undercoating layer 3 consisting of the mixture composed of the tantalum oxide and the zinc sulfide, the recording layer 4 consisting of a GeSbTe alloy thin film, the overcoating layer 5 consisting of the same material as the material of the undercoating layer 3 and a reflection layer 6 consisting of an Al alloy are formed by sputtering on a disk-shaped transparent substrate 1. The nitrogen component or both of the nitrogen component and the oxygen component are imparted to the undercoating layer 3 and the overcoating layer 5 by sputtering using a sintered compact of a material formed by mixing the tantalum oxide and the zinc sulfide as a target and using a gas mixture formed by adding nitrogen or both of the nitrogen and oxygen to argon.