Perpendicular magnetic recording medium and method for manufacturing same

a magnetic recording medium and perpendicular magnetic technology, applied in the field of perpendicular magnetic recording medium, can solve the problems of difficult to take out magnetic flux in high density recording, high media noise, difficult to promote segregation, etc., and achieve enhanced signal output, improved s/n, and reduced noise

Inactive Publication Date: 2005-08-25
FUJI ELECTRIC DEVICE TECH CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014] Therefore, an object of the present invention is to provide a perpendicular magnetic recording medium and a manufacturing method that allows reduction of noise and enhancement of S / N (output signal to noise ratio).
[0022] In a perpendicular magnetic recording medium according to the invention, each magnetic crystal grain in the magnetic recording layer has a multilayer structure and has a configuration like a truncated cone shape in which the diameter of the crystal grain of final layer deposited in the film surface side at the final stage is smaller than the diameter of the crystal grain in the initial layer deposited in the substrate side at the initial stage. As a result, signal output is enhanced and noises are reduced to improve S / N (signal output to noise ratio).
[0023] According to the invention, magnetic crystal grains having multilayer structure can be mass produced by a simple manufacturing method. A perpendicular magnetic recording medium of the invention attains high recording resolution and achieves high density recording.

Problems solved by technology

In a perpendicular magnetic recording medium, however, the heating or substrate bias voltage application as conducted in the in-plane medium can segregate only a small amount of chromium, resulting in high media noise.
It has been difficult, however, to promote segregation in the granular magnetic recording layer by a process that is suitable for mass production.
At the same time this means that taking out magnetic flux in high density recording is difficult.
While a medium structure is required that achieves low noise and high signal output even at high recording density, such a medium structure has never been proposed.
There have been various problems in achieving the desired result.
Because deposition of a granular film with substrate heating raises problems of mixing a nonmagnetic phase with an alloy phase and / or oxidation or nitridation of cobalt, the film must be deposited without substrate heating.
However, film deposition without substrate heating cannot achieve sufficient isolation between the alloy phase and the nonmagnetic phase, which raises a problem of insufficient noise reduction.
Heat treatment at such a high temperature and for relatively long time is not suitable for mass production.
It is unfortunately very difficult to obtain a film that is homogeneous over a disk surface using an arrangement that places two targets in equipment for mass production.
Therefore, this technique is not suitable for mass production.
However, none of these techniques is suitable for mass production.

Method used

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  • Perpendicular magnetic recording medium and method for manufacturing same
  • Perpendicular magnetic recording medium and method for manufacturing same
  • Perpendicular magnetic recording medium and method for manufacturing same

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Experimental program
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first embodiment

[0034] This embodiment is described with reference to FIGS. 1 through 3, which disclose the structure of the medium.

[0035]FIG. 1 is a schematic sectional view of a structure of perpendicular magnetic recording medium 100 of the invention. Perpendicular magnetic recording medium 100 comprises nonmagnetic substrate 1, soft magnetic backing layer 2, nonmagnetic intermediate layer 3, magnetic recording layer 4, protective film 5, and liquid lubricant layer 6. A seed layer or a soft magnetic intermediate layer can be appropriately inserted between soft magnetic backing layer 2 and nonmagnetic intermediate layer 3.

[0036] Nonmagnetic substrate 1 can be any substrate having a smooth surface commonly used in a magnetic recording; medium. The substrate can be composed of NiP plated aluminum alloy, strengthened glass, crystallized glass, for example.

[0037] Soft magnetic backing layer 2 can be composed of crystalline FeTaC, Sendust alloy (FeSiAl), or amorphous cobalt alloy of CoZrNb or CoTaZ...

second embodiment

[0053] The second embodiment of the invention is described below with reference to FIG. 4. Corresponding parts from the first embodiment are given the same symbol, and their description is omitted.

[0054] The second embodiment describes a manufacturing method for perpendicular magnetic recording medium 100 comprising magnetic recording layer 4 that includes magnetic crystal grains 10 with a configuration like a truncated cone shape, in which a grain diameter on the film surface is smaller than a grain diameter at the initial stage. In the manufacturing method, the amount of oxygen or nitrogen introduced in the process of depositing magnetic recording layer 4 is adjusted to vary the amount of oxidized or nitrided metals in the magnetic recording material and vary diameter of magnetic crystal grains 10, thereby forming a truncated cone shape. More particularly, the amount of oxygen introduced in the process of depositing the magnetic recording layer is adjusted to vary the amount of o...

manufacturing example 1

[0058] A chemically reinforced glass substrate (N-10 glass substrate made by HOYA Corporation, for example) having a smooth surface was used for nonmagnetic substrate 1. After cleaning, nonmagnetic substrate 1 was introduced into a sputtering apparatus. A CoZrNb amorphous soft magnetic backing layer 2 with a thickness of 200 nm was deposited using a target of 87 at % Co-5 at % Zr-8 at % Nb. Then, a NiFeSi underlayer 11 nm thick was deposited using a permalloy target of 82 at % Ni-12 at % Fe-6 at % Si. Subsequently, nonmagnetic intermediate layer 3 of ruthenium having a thickness of 10 nm was deposited under an argon gas pressure of 4.0 Pa using a ruthenium target.

[0059] Then magnetic recording layer 4 of CoCrPt—SiO2 having a thickness of 10 nm was deposited under a gas pressure of 5.3 Pa using a target of 90 mol % (74 at % Co-12 at % Cr-14 at % Pt)-10 mol % (SiO2). In this step, the initial deposition from the start of deposition to a film thickness of 0.5 nm was conducted in an at...

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Abstract

A perpendicular magnetic recording medium is disclosed in which each magnetic crystal grain in the magnetic recording layer has a multilayer structure and has a configuration like a truncated cone shape, in which the crystal grain of the final layer deposited in the film surface side at the final stage is smaller than the diameter of the crystal grain in the initial layer deposited on the substrate side at the initial stage. The invention improves S / N (signal output to noise ratio) by enhancing signal output and reducing noises. The medium is produced by a simple manufacturing method suitable for mass production, and provides a medium of high recording density by improving recording resolution.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from Japanese application Serial No. JP PA 2004-010427, filed on Jan. 23, 2004, the contents of which are incorporated herein in their entirety. BACKGROUND OF THE INVENTION [0002] A. Field of the Invention [0003] The invention relates generally to a perpendicular magnetic recording medium mounted on various magnetic recording apparatuses and a method for manufacturing such a medium. [0004] B. Description of the Related Art [0005] In technologies for achieving high density magnetic recording, perpendicular magnetic recording is drawing attention as a substitute for conventional longitudinal magnetic recording. [0006] Alloy materials of CoCrPt, CoCrTa, and the like have been used for a magnetic recording layer material of a perpendicular magnetic recording medium employing perpendicular magnetic recording. In these alloy materials, the nonmagnetic substance chromium segregates into a grain boundary and mag...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B5/64G11B5/66G11B5/65G11B5/667G11B5/738G11B5/851
CPCG11B5/64G11B5/851G11B5/656G11B5/65G11B5/658G11B5/674G11B5/657G11B5/672
Inventor TAKENOIRI, SHUNJISAKAI, YASUSHI
Owner FUJI ELECTRIC DEVICE TECH CO
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