Patent ID: 6511788
Filing Date: 2003-01-28
Classification: G11B,Y10S

Abstract:
A multi-layered optical disc comprising layers in the following order:a light transmitting protective layer 10 &mgr;m to 177 &mgr;m in thickness; a first information recording layer including a first film of a phase change material; a transparent layer; a semi-transparent enhancement film; a second information recording layer including a second film of a phase change material; a reflecting film; and a support substrate 0.3 to 1.2 mm in thickness, the support substrate carrying a guide groove comprising a pattern of crests and recesses, where the second film of a phase change material has a layer of a crystallization promoting film followed by a layer of an enhancement film formed on at least one of its sides; the phase change material is formed of a binary alloy, a ternary alloy, a quaternary alloy, a quinary alloy, or nitrides and oxides thereof; and the crystallization promoting film is formed of a material containing at least one of Ge, GeC, Sn, SnC, Al, AlC, Ga, GaC, In, and InC, or chlorides and oxides thereof.