Patent ID: 7947353

Claim:
An information recording medium comprising at least two information layers each having a recording layer which can generate optically detectable phase-change, wherein one information layer near a light incoming side is referred to as an information layer a, and the other information layer distant from the light incoming side as an information layer b, wherein: said information layer a comprises, at least, a dielectric layer 1 a , a recording layer a, a dielectric layer 2 a and a reflective layer a in this order from the light incoming side; and said information layer b comprises, at least, a dielectric layer 1 b , a recording layer b, a dielectric layer 2 b and a reflective layer b in this order from the light incoming side, said dielectric layers 1 a and 2 a are in contact with the recording layer a; and said dielectric layers 1 b and 2 b are in contact with the recording layer b, each of said dielectric layer 1 a and said dielectric layer 1 b contains at least one atom selected from an oxygen atom, a nitrogen atom and a fluorine atom, provided that each of said dielectric layers 1 a and 1 b contains at least one element selected from Al, Si, Cr, Ta, Mo, W, Zr and Hf, when containing an oxygen atom, or contains at least one element selected from Al, B, Ge, Si, Ti and Zr, when containing a nitrogen atom, or contains at least one element selected from Dy, Er, Eu, Ce, Bi and La, when containing a fluorine atom, each of said dielectric layers 2 a and 2 b contains at least one element selected from Zr, Si, Cr, In, Ga and Hf, and an oxygen atom, a composition of said dielectric layer 1 a is the same as a composition of said dielectric layer 1 b ; a composition of said recording layer a is the same as a composition of said recording layer b; and a composition of said dielectric layer 2 a is the same as a composition of said dielectric layer 2 b , and each of said recording layers a and b comprises a Ge—Bi—Te—M″-based material represented by the following formula (11): Ge a Bi b Te d M″ 100-a-b-d (at%) (11) wherein M″ represents at least one element selected from Al, Ga and In; and a, b and d satisfy the relationships of 25 ≦a ≦60, 0 <b ≦18, 35≦d ≦55, and 82 ≦a+b+d <100.