Management technique of friction coefficient based on surface roughness, substrate for information recording medium, information recording medium and manufacture method thereof

An information recording medium substrate having a surface roughness of Rmax 15 nm or less,

• wherein for the surface of said substrate, when a depth corresponds to 20 to 45% of Rmax from a bearing height (real peak height) corresponding to a bearing area value of 0.2% to 1.0% is set as a slice level, the bearing area value (offset bearing area value) is 90% or less.

An information recording medium having a surface roughness of Rmax 15 nm or less on a medium surface,

• wherein for a medium surface of said information recording medium, a bearing area value (offset bearing area value) in a depth of 0.5 to 5 nm (predetermined slice level) from a bearing height (real peak height) corresponding to the bearing area value of 0.2% to 1.0% is 90% or less.

An information recording medium having a surface roughness of Rmax 15 nm or less on a medium surface,

• wherein for a medium surface of said information recording medium, when a depth corresponds to 20 to 45% of Rmax from a bearing height (real peak height) corresponding to a bearing area value of 0.2% to 1.0% is set as a slice level, the bearing area value (offset bearing area value) is 90% or less.

A manufacture method of a glass substrate for an information recording medium, comprising steps of:

• immersing the glass substrate in a heated chemical reinforcing treatment liquid, and subjecting an ion on a glass substrate surface layer to ion exchange with an ion in the chemical reinforcing treatment liquid to chemically reinforce the glass substrate;
• and
• treating the surface of the glass substrate drawn up from the chemical reinforcing treatment liquid with a treatment liquid containing silicofluoric acid.

A management technique of a friction coefficient based on a surface roughness in an information recording medium having a surface roughness of Rmax 15 nm or less on a medium surface, comprising steps of:

• using a bearing area in a depth of 0.5 to 7 nm (slice level) from a maximum height (Rmax) by AFM measurement to manage the friction coefficient based on the surface roughness.

A management technique of a friction coefficient based on a surface roughness in an information recording medium having a surface roughness of Rmax 15 nm or less on a medium surface, comprising steps of:

• using a bearing area when a depth corresponds to 20 to 40% of Rmax from a maximum height (Rmax) by AFM measurement is set as a slice level, and managing the friction coefficient based on the surface roughness.

A management technique of a surface state of an information recording medium substrate surface having a surface roughness of Rmax 15 nm or less, said technique comprising steps of:

• when repeated measurement of a bearing curve is performed by an atomic force microscope (AFM), obtaining a bearing area value at which a measured value of a bearing height rapidly starts to scatter in the vicinity of a maximum protrusion height (BA=0%);
• and
• utilizing various AFM measured values excluding data from BA=0% to the bearing area value at which the bearing height measured value rapidly starts to scatter.

A management technique of a surface state of an information recording medium surface having a surface roughness of Rmax 15 nm or less, said technique comprising steps of:

• when repeated measurement of a bearing curve is performed by an atomic force microscope (AFM), obtaining a bearing area value at which a measured value of a bearing height rapidly starts to scatter in the vicinity of a maximum protrusion height (BA=0%);
• and
• utilizing various AFM measured values excluding data from BA=0% to the bearing area value at which the bearing height measured value rapidly starts to scatter.