Master medium for magnetic transfer including metal disk with relief or recess pattern

Abstract

A master medium for use in magnetic transfer of information includes a metal disk which has a first relief or recess pattern representing the information. The metal disk is produced by exposing a photoresist film formed on a base disk with a laser or electron beam modulated with the information while rotating the base disk; developing the photoresist film so as to form an original disk having a second relief or recess pattern; depositing metal on the original disk so as to mold the metal disk on the original disk; and removing the metal disk from the original disk.

What is claimed is:  
     
         1 . A master medium for use in magnetic transfer of information, comprising a metal disk which has a first relief or recess pattern representing said information, where said metal disk is produced by exposing a photoresist film formed on a base disk with a laser or electron beam modulated with said information while rotating the base disk, developing the photoresist film so as to form an original disk having a second relief or recess pattern, depositing metal on said original disk so as to mold said metal disk on said original disk, and removing said metal disk from said original disk.  
     
     
         2 . A master medium according to    claim 1   , wherein said original disk is formed by etching said base disk after said photoresist film is developed.  
     
     
         3 . A master medium according to    claim 1   , wherein said base disk is made of glass or quartz.  
     
     
         4 . A master medium according to    claim 1   , wherein said original disk is made of a material containing Ni as a main component.  
     
     
         5 . A master medium according to    claim 1   , wherein said first relief or recess pattern has a height or depth of 80 to 800 nm.  
     
     
         6 . A master medium according to    claim 1   , further comprising a soft magnetic layer formed on said first relief or recess pattern.  
     
     
         7 . A master medium according to    claim 6   , further comprising a nonmagnetic layer formed between said soft magnetic layer and said first relief or recess pattern.  
     
     
         8 . A master medium according to    claim 6   , wherein said soft magnetic layer has a thickness of 50 to 500 nm.  
     
     
         9 . A master medium according to    claim 1   , further comprising a diamond-like carbon protection layer as an uppermost layer.  
     
     
         10 . A master medium according to    claim 1   , wherein said first relief or recess pattern is elongated in a radial direction.  
     
     
         11 . A master medium for use in magnetic transfer of information, comprising a metal disk which has a first relief or recess pattern representing said information, where said metal disk is produced by exposing a photoresist film formed on a base disk with a laser or electron beam modulated with said information while rotating the base disk, developing the photoresist film so as to form a first original disk having a second relief or recess pattern, depositing metal on said first original disk so as to mold on said first original disk a second original disk having a third relief or recess pattern, removing the second original disk from said first original disk, depositing metal on said second original disk so as to mold said metal disk on said second original disk, and removing the metal disk from said second original disk.  
     
     
         12 . A master medium according to    claim 11   , wherein said first original disk is formed by etching said base disk after said photoresist film is developed.  
     
     
         13 . A master medium according to    claim 11   , wherein said second original disk is formed by pressing a resin solution on said first original disk, curing said resin solution so as to mold said second original disk on said first original disk, instead of depositing metal on said first original disk.  
     
     
         14 . A master medium according to    claim 11   , wherein said base disk is made of glass or quartz.  
     
     
         15 . A master medium according to    claim 11   , wherein said original disk is made of a material containing Ni as a main component.  
     
     
         16 . A master medium according to    claim 11   , wherein said first relief or recess pattern has a height or depth of 80 to 800 nm.  
     
     
         17 . A master medium according to    claim 11   , further comprising a soft magnetic layer formed on said first relief or recess pattern.  
     
     
         18 . A master medium according to    claim 17   , further comprising a nonmagnetic layer formed between said soft magnetic layer and said first relief or recess pattern.  
     
     
         19 . A master medium according to    claim 17   , wherein said soft magnetic layer has a thickness of 50 to 500 nm.  
     
     
         20 . A master medium according to    claim 11   , further comprising a diamond-like carbon protection layer as an uppermost layer.  
     
     
         21 . A master medium according to    claim 11   , wherein said first relief or recess pattern is elongated in a radial direction.  
     
     
         22 . A master medium for use in magnetic transfer of information, comprising a metal disk which has a first relief or recess pattern representing said information, where said metal disk is produced by exposing a photoresist film formed on a base disk with a laser or electron beam modulated with said information while rotating the base disk, developing the photoresist film so as to form a first original disk having a second relief or recess pattern, depositing metal on said first original disk so as to mold on said first original disk a second original disk having a third relief or recess pattern, removing the second original disk from said first original disk, depositing metal on said second original disk so as to mold on said second original disk a third original disk having a fourth relief or recess pattern, removing the third original disk from said second original disk, depositing metal on said third original disk so as to mold said metal disk on said third original disk, and removing the metal disk from said third original disk.  
     
     
         23 . A master medium according to    claim 22   , wherein said first original disk is formed by etching said base disk after said photoresist film is developed.  
     
     
         24 . A master medium according to    claim 22   , wherein said second original disk is formed by pressing a resin solution on said first original disk, curing said resin solution so as to mold said second original disk on said first original disk, instead of depositing metal on said first original disk.  
     
     
         25 . A master medium according to    claim 22   , wherein said third original disk is formed by pressing a resin solution on said second original disk, curing said resin solution so as to mold said third original disk on said second original disk, instead of depositing metal on said second original disk.  
     
     
         26 . A master medium according to    claim 22   , wherein said base disk is made of glass or quartz.  
     
     
         27 . A master medium according to    claim 22   , wherein said original disk is made of a material containing Ni as a main component.  
     
     
         28 . A master medium according to    claim 22   , wherein said first relief or recess pattern has a height or depth of 80 to 800 nm.  
     
     
         29 . A master medium according to    claim 22   , further comprising a soft magnetic layer formed on said first relief or recess pattern.  
     
     
         30 . A master medium according to    claim 29   , further comprising a nonmagnetic layer formed between said soft magnetic layer and said first relief or recess pattern.  
     
     
         31 . A master medium according to    claim 29   , wherein said soft magnetic layer has a thickness of 50 to 500 nm.  
     
     
         32 . A master medium according to    claim 22   , further comprising a diamond-like carbon protection layer as an uppermost layer.  
     
     
         33 . A master medium according to    claim 22   , wherein said first relief or recess pattern is elongated in a radial direction.