Optical information recording medium and method for producing the same

An optical information-recording medium comprising:

• a substrate which includes a land, a groove having a flat bottom surface, and in-groove pits having flat bottom surfaces, respectively, formed on one surface of the substrate;
• a reflective layer which is formed on the one surface;
• a recording layer which contains an organic dye and is formed on the reflective layer;
• a protective layer which is formed on the recording layer;
• and
• a cover layer which is formed on the protective layer, wherein:
• dp/dg<Tp′/Tg′ is satisfied provided that dg represents a depth from a land surface of the substrate to the bottom surface of the groove, dp represents a depth from the land surface of the substrate to the bottom surface of the in-groove pit, Tg′ represents a recess depth of the recording layer from an interface between the recording layer and the protective layer on the land surface to the interface between the recording layer and the protective layer at the groove, and Tp′ represents a recess depth of the recording layer from the interface between the recording layer and the protective layer on the land surface to the interface between the recording layer and the protective layer at the in-groove pit.

A method for producing an optical information-recording medium comprising:

• a master disk-cutting step of forming, on a master disk, a groove and in-groove pits formed on the groove;
• a stamper-manufacturing step of manufacturing a stamper to which a corresponding pattern to the groove and the in-groove pits on the master disk is transferred;
• and
• a substrate-replicating step of replicating a substrate from the stamper, and a film-forming step of forming at least one layer on a surface of the replicated substrate, wherein:
• the master disk-cutting step includes a groove exposure step of forming a groove pattern on the master disk by exposing a photoresist formed on a surface of the master disk with a light beam having a first exposure intensity and an in-groove pit exposure step of forming an in-groove pit pattern on the master disk by exposing the photoresist formed on the surface of the master disk with a light beam having a second exposure intensity which is higher than the first exposure intensity;
• and
• a period of time, in which exposure is performed at a third exposure intensity lower than the first exposure intensity, is provided between the groove exposure step and the in-groove pit exposure step.

A method for producing a stamper comprising:

• a master disk-cutting step of forming, on a master disk, a groove and in-groove pits formed on the groove;
• and
• a stamper-manufacturing step of manufacturing a stamper to which a corresponding pattern to the groove and the in-groove pits on the master disk is transferred, wherein:
• the master disk-cutting step includes a groove exposure step of forming a groove pattern on the master disk by exposing a photoresist formed on a surface of the master disk with a light beam having a first exposure intensity and an in-groove pit exposure step of forming an in-groove pit pattern on the master disk by exposing the photoresist formed on the surface of the master disk with a light beam having a second exposure intensity which is higher than the first exposure intensity;
• and
• a period of time, in which exposure is performed at a third exposure intensity lower than the first exposure intensity, is provided between the groove exposure step and the in-groove pit exposure step.