Magnetic recording medium and method of fabricating the same
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsMasahiro Birukawa, Yoshihiko Kudoh
Life of this patent
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Abstract
A read-only disk and a write-only disk recorded at high density having a magneto-optical film differing in coercive force depending on the information to be recorded disposed on a substrate. In the read-only and write-once disks, signals can be read employing only part of the irradiation beam, and thus super-resolution reading is realized.
Claims9
A magnetic recording medium, being a magneto-optical recording medium possessing a read-only portion and a rewritable portion, wherein the read-only portion is composed of a magnetic film possessing different magnetic anisotropy depending on informations to be recorded, and the rewritable portion is composed of a magnetic film possessing a uniform magnetic characteristic regardless of the informations to be recorded.
A magnetic recording medium, being a magneto-optical recording medium possessing a write-once portion and a rewritable portion, wherein the magnetic anisotropy in a written mark part is different from the other part in the write-once portion, and the rewritable portion is composed of a magnetic film possessing a uniform magnetic characteristic regardless of the presence or absence of written mark.
A manufacturing process of magnetic recording medium comprising a step of applying a photo resist on a glass master-substrate and heating, a step of cutting the photo resist by a laser modulated in power depending on recording information, a step of developing in a developing solution after cutting, a step of roughening the exposed portion of the glass master-substrate by plasma ion etching in using a mixed gas of CF.sub.4 gas and Ne gas or a mixed gas of CF.sub.4 gas and Ar gas, form the photo resist surface side after developing, a step of removing all of the photo resist formed on the glass master-substrate after plasma ion etching, a step of forming a stamper by electroforming on the glass master-substrate after removing the photo resist, a step of peeling off the stamper from the glass master-substrate, a step of forming a substrate possessing portions different in the roughness of surface corresponding to the recording information by using the stamper, and a step of depositing a magnetic film on the substrate.
A manufacturing method of magnetic recording medium comprising a step of applying a photo resist on a glass master-substrate and heating, a step of roughening the photo resist surface by plasma ion etching in a mixed gas of N.sub.2 gas and He gas or a mixed gas of O.sub.2 gas and He gas, a step of smoothing by softening the roughened photo resist surface by laser modulated in power depending on the recording information after plasma ion etching, a step of forming a stamper by electroforming on the photo resist after cutting, a step of peeling off the stamper from the glass master-substrate and photo resist, a step of forming a substrate possessing portions different in the roughness of surface depending on the recording information by using the stamper, and a step of depositing a magnetic film on the substrate.
A recording method of magnetic recording medium, wherein by recording at an intensity of light capable of mutually diffusing a multi-layered magnetic film and additive element film, when recording information into a magneto-optical recording medium composed of a magnetic film possessing a certain magnetic anisotropy and a film of an additive element for increasing or decreasing the magnetic anisotropy of the magnetic film, such portions are formed that are different in a magnitude of magnetic anisotropy, corresponding to the recording information, and are different in a coercive force of the magnetic film in each portion.
A recording method of magnetic recording medium, wherein by recording at an intensity of light capable of growing crystal grains or micro-structures observed by transmission electron microscope in a magnetic film, when recording information into a magneto-optical recording medium of which magnetic film is composed of a crystalline magnetic film, such portions are formed that are different in a size of micro-structures or crystal grains, depending on the recording information, and are different in a coercive force of the magnetic film in each portion.
A reading method of magneto-optical recording medium wherein varying a status of magnetization of a magneto-optical recording medium by a bias magnetic field, while reading a magneto-optical recording medium providing magneto-optical magnetic films possessing different coercive forces depending on informations to be recorded, at least in a part.
Dependencies are inferred from the claim text.