Dual-layer phase-change information recording medium and recording method thereof

A method for recording in a dual-layer phase-change information recording medium comprising the step of controlling the area of an amorphous mark in three levels or more,

• wherein the recording is performed in a dual-layer phase-change information recording medium comprising a first substrate, a first information layer, an intermediate layer, a second information layer and a second substrate which are disposed in this order,
• wherein information is recorded and reproduced by irradiating a laser beam from the side of the first substrate;
• the first information layer and the second information layer respectively comprise a recording layer in which information may be recorded by phase change between crystalline state and amorphous state caused by the irradiation of a light;
• and
• a first recording layer as the recording layer of the first information layer as well as a second recording layer as the recording layer of the second information layer respectively comprise materials represented by the following composition formulae:
• Sbα1Teβ1Geγ1M1δ1;
• the first recording layer;
• Sbα2Teβ2Geγ2M2δ2;
• the second recording layer;
• wherein M1 and M2 are any one element selected from Ag, In, Se, Sn, Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Bi, Si, Dy, Pd, Pt, Au, S, B, C and P;
• α1, β1, γ1, δ1, α2, β2, γ2 and δ2 denote percentages by atom and satisfy the following relations:
• α1+β1+γ1+δ1=α2+β2+γ2+δ2=100;
• 50≦α1≦75;
• 25≦β1≦40;
• 0<γ1≦10;
• 0≦δ1≦10;
• 60≦α2≦85;
• 15≦β2≦30;
• 0<γ2≦10;
• 0≦δ2≦10;
• and
• β2+γ2<β1+γ1≦β2+γ2+20.