Information recording medium, method for producing same, and sputtering target

An information recording medium that records or reproduces information by irradiation with a laser beam, the information recording medium comprising three or more information layers,

• the three or more information layers including an information layer, the information layer including a first dielectric film, a recording film, and a second dielectric film in this order from a farther end toward a nearer end of the information layer from a laser beam-irradiated surface of the information recording medium,
• the first dielectric film and the second dielectric film containing an oxide of D3, where the D3 representing at least one element selected from a group consisting of zirconium (Zr), indium (In), tin (Sn), and silicon (Si), the recording film containing at least tungsten (W), copper (Cu), manganese (Mn), titanium (Ti), and oxygen,
• the W, the Cu, the Mn, and the Ti except the oxygen in the recording film satisfying a following formula (2):
• WxCuyMnzTi100-x-y-z (atom %) (2),
• wherein
• x, y, and z satisfy 15≤x≤60, y≤z, 0<z≤40, and 60≤x+y+z≤98.

A method for producing an information recording medium, the method comprising steps of respectively forming three or more information layers included in the information recording medium,

• wherein at least one of the steps of respectively forming the three or more information layers includes:
• forming a first dielectric film containing an oxide of D1 by sputtering with use of a target containing the D1, where the D1 representing at least one element selected from a first group consisting of niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), bismuth (Bi), and cerium (Ce);
• and
• forming a recoding film containing at least tungsten (W), copper (Cu), manganese (Mn), and oxygen, and further containing M by sputtering with use of a target containing at least W, Cu, and Mn and further containing the M, where the M representing at least one element selected from a second group consisting of niobium (Nb), molybdenum (Mo), tantalum (Ta), and titanium (Ti),
• the W, the Cu, the Mn, and the M except the oxygen in the target used in a step for forming the recording film satisfying a following formula (1):
• WxCuyMnzM100-x-y-z (atom %) (1),
• wherein
• x, y, and z satisfy 15≤x≤60, y≤z, 0<z≤40, and 60≤x+y+z≤98.

A sputtering target for forming a recording film of an information recording medium, the sputtering target comprising:

• at least tungsten (W), copper (Cu), and manganese (Mn);
• and
• M, where the M representing at least one element selected from a group consisting of niobium (Nb), molybdenum (Mo), tantalum (Ta), and titanium (Ti), the W, the Cu, the Mn, and the M except oxygen satisfying a following formula (1);
• WxCuyMnzM100-x-y-z (atom %) (1),
• wherein
• x, y, and z satisfy 15≤x≤60, y≤z, 0<z≤40, and 60≤x+y+z≤98.