JPH05303736A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics, such as coercive force and residual magnetization Brdelta, and to enable high-density recording by introducing a compressive stress and/or local stress into the plane of a magnetic thin film by an ion implantation method. CONSTITUTION:This magnetic recording medium is produced by forming a magnetic thin film layer of a Co system by sputtering, vacuum vapor deposition and other film forming methods on a first ground surface layer or direct film formation on a substrate consisting of glass, aluminum, etc., and implanting the ions of >=1kinds selected from B, C, N, O or rare gases, such as Ar and Ne, etc., by an ion implantation device into the plane of the magnetic thin film after or before the formation of a protective film consisting of C, etc., thereon. As a result, only the coercive force Hc is increased without degrading the residual magnetization Brdelta.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium and a manufacturing method thereof, and more particularly to a magnetic recording medium such as a sputter hard disk used as an external recording medium for a computer and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, a hard disk is a typical magnetic recording medium. Such conventional magnetic recording media include an iron oxide coating type and a Co plating type. Instead of these, magnetic recording media capable of higher density recording have been developed and put into practical use.

This high density magnetic recording medium has a structure as shown in FIG. 3, and the substrate 1 is an Al alloy provided with Ni-P plating or a glass substrate. Then, the base layer 2 made of a Cr film is formed on the substrate 1.
(1000-3000Å), magnetic film 3 (500-700Å) made of Co alloy film, and protective film 4 made of C (300-
A film having a three-layer structure composed of 400Å) is formed.

As a method for manufacturing the magnetic recording medium shown in FIG. 3, a sputtering method is adopted, which is carried out by sequentially forming the above-mentioned films on the substrate 1. This film is used for mass production. In-line sputter equipment is used. The magnetic characteristics of the magnetic recording medium obtained by this method are as follows: coercive force Hc: 1000 to 1500 Oe, squareness ratio S:
0.75 to 0.95

However, recently, there has been a strong demand for a magnetic recording medium capable of higher density recording, for example, it has a coercive force Hc of 1500 to 2000 Oe and is accompanied by a narrower track. Development of a magnetic recording medium having a high residual magnetization Brδ has been earnestly desired in order to compensate for the reduction in reproducing power.

However, in order to increase the coercive force of the magnetic recording medium in this way, there is a limit to the improvement, that is, the coercive force Hc (Oe) is the residual magnetization Br of the recording medium × the film thickness δ. Shows a negative correlation, and the coercive force Hc increases when the residual magnetization Brδ is decreased.

Therefore, the coercive force H is reduced by reducing the thickness of the magnetic film.
Although it is possible to increase c, in this case, since the reproduction output decreases, it is necessary to make the distance between the magnetic recording medium and the head extremely small as a countermeasure, so that the quality of the surface of the magnetic recording medium is reduced. Management becomes extremely difficult.

[0008]

In view of various problems and circumstances of the conventional magnetic recording medium described above, the present invention has been earnestly studied, and as a result, the coercive force Hc and the residual magnetization Brδ, etc. Has developed a magnetic recording medium capable of high-density recording, which has excellent magnetic characteristics, and a manufacturing method thereof.

[0009]

A magnetic recording medium and a method for manufacturing the same according to the present invention are a magnetic recording medium having a Co type magnetic thin film formed on a substrate through an underlayer film or directly. A magnetic recording medium having a high in-plane coercive force, wherein the magnetic thin film has a compressive stress and / or a local stress introduced into the thin film surface by ion implantation, is the first invention, and is used as a horizontal magnetic recording medium. After forming a Co-based magnetic thin film on a substrate by a thin film forming method,
Saturation magnetization of the thin film is improved by implanting ions of one or more rare gases such as B, C, N, O and Ar, Ne into the surface of the magnetic thin film with a doping amount of 1 × 10 ¹⁶ / cm ² or more. The present invention comprises two inventions, the second invention being a method of manufacturing a magnetic recording medium, which is characterized by increasing the in-plane coercive force without lowering.

The magnetic recording medium and the manufacturing method thereof according to the present invention will be described in detail below.

That is, the magnetic recording medium according to the present invention comprises Co
System magnetic thin film layer on the substrate such as glass, aluminum,
After forming a protective film such as C on the first base film or directly on the substrate by sputtering, vacuum evaporation or other film forming method, or before forming the protective film A magnetic recording medium is manufactured by ion-implanting at least one selected from B, C, N, O, and rare gases such as Ar and Ne into the surface of the magnetic thin film by an ion-implanting device. And the coercive force Hc of the magnetic recording medium can be reduced without lowering the residual magnetization Brδ.
It is possible to increase only

As described above, the magnetic recording medium and the method for manufacturing the same according to the present invention are subjected to the ion implantation treatment after the Co type magnetic recording layer is formed on the substrate by a film forming method such as sputtering or vacuum deposition. Is going.

This Co-based magnetic recording medium has a strong uniaxial magnetic anisotropy in the C-axis direction of cobalt hexagonal crystal,
Further, since the film is formed by a vacuum film forming method such as vacuum deposition or sputtering, the crystal grain size is extremely fine,
Therefore, it is difficult to move the domain wall in the magnetic thin film, and as a result, a high coercive force Hc is obtained.

As described above, in the magnetic recording medium and the manufacturing method thereof according to the present invention, the coercive force Hc of the conventional Co-based thin film can be given by ion implantation to give a higher coercive force Hc. Is.

That is, B, C, N, O and one or more kinds of rare gases such as Ar and Ne are ion-implanted into the Co-based magnetic thin film layer, and first, the surface in the Co-based magnetic thin film is first of all. A compressive stress remains inside, and this compressive stress is C
Since the o-based magnetic thin film has a negative magnetostriction constant, it has the effect of increasing the in-plane magnetic anisotropy by the magnetoelastic effect and increasing the coercive force Hc in the in-plane direction of the magnetic thin film.

Secondly, by ion-implanting the Co-based magnetic thin film layer, a number of structural defects and local stresses associated therewith are introduced into the Co-based magnetic thin film, and the magnetic domain wall generated in the magnetic thin film is removed. Coercive force H by suppressing movement
It has the effect of increasing c.

The remanent magnetization Brδ of the Co-based magnetic thin film is lowered by ion implantation, which lowers the saturation magnetism of this film and also reduces the film thickness due to loss of the surface by sputtering. However, it is impossible to increase the implantation amount by ion implantation to such a degree that the saturation magnetism is lowered, and the reduction of the residual magnetization Brδ is mainly caused by the reduction of the film thickness.

Therefore, the coercive force Hc is obtained by the ion implantation.
Is increased but the residual magnetization Brδ is decreased,
Since the effect of increasing the coercive force Hc by the ion implantation effect is extremely large, it is possible to increase only the coercive force Hc without actually decreasing the remanent magnetization Brδ.

[0019]

EXAMPLES Examples of the magnetic recording medium and the manufacturing method thereof according to the present invention will be described.

[0020]

[Example 1] C as a base film on a glass substrate at room temperature
After forming an r film of 2000Å, CoNiCr
Three layers of an alloy magnetic film 600Å and a C protective film 300Å were formed. The Cr film, Co, Ni, Cr alloy film, and C protective film were all formed by sputtering, and the magnetic film used was Co-30Ni-7.5Cr alloy.

20 K of N was added to the formed magnetic recording medium.
ev, 120 μA injection condition, 1 × 10 ¹⁶ ion
s / cm ² , 3 × 10 ¹⁶ ions / cm ² , 5 × 10 ¹⁶ i
Ion implantation was performed at an implantation amount of ons / cm ² , and coercive force Hc and residual magnetization Brδ were measured.

FIG. 1 shows the coercive force Hc and the remanent magnetization Brδ, but when the injection amount is increased, the coercive force Hc becomes 945O.
abruptly increased from e to 1235 Oe and the residual magnetization Br
It can be seen that δ maintains a value of 450 Gμm, which is a substantially constant value, before the injection.

[0023]

[Example 2] A CoCrPt alloy magnetic film 500Å and a C protective film 300Å were directly formed on an NiP-plated Al substrate by sputtering without providing a base film. For this magnetic film, a Co-10Cr-15Pt alloy was used.

The substrate temperature before film formation was 200 ° C. After the film formation, B was injected under the conditions of 20 Kev and 260 μA under the condition of 2 × 10 ¹⁶ ions / cm ² , 4 × 10 ¹⁶ / io.
Implantation was performed at an injection rate of ns / cm ² and 6 × 10 ¹⁶ ions / cm ₂ , and coercive force Hc and residual magnetization Brδ were measured.

FIG. 2 shows the coercive force Hc and the residual magnetization Brδ, and the coercive force Hc becomes 1950O as the injection amount increases.
From e to 2260 Oe, the remanent magnetization Brδ is maintained at a substantially constant value of 310 Gμm before injection.

[0025]

As described above, since the magnetic recording medium and the method for manufacturing the same according to the present invention have the above-mentioned structure, they have a high residual magnetization Brδ and are also excellent in coercive force Hc. The magnetic recording medium, that is, the magnetic recording medium capable of high-density recording can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship among an ion implantation amount, a coercive force Hc, and a residual magnetization Brδ in Example 1.

FIG. 2 is a diagram showing a relationship between an ion implantation amount, a coercive force Hc, and a residual magnetization Brδ in Example 2;

FIG. 3 is a schematic cross-sectional view of a high density magnetic recording medium.

[Explanation of symbols]

 1 ... Substrate 2 ... Underlayer 3 ... Magnetic film 4 ... Protective film

Claims (2)

[Claims] 1. A magnetic recording medium having a Co-based magnetic thin film formed directly on or through a base film on a substrate, wherein the magnetic thin film is subjected to compressive stress and / or local in-plane by thin film ion implantation. A magnetic recording medium having a high in-plane coercive force, characterized in that stress is introduced. 2. A Co-based magnetic thin film used as a horizontal magnetic recording medium is formed on a substrate by a thin film forming method, and B, C, N, O and Ar N
The in-plane coercive force is increased without lowering the saturation magnetization of the thin film by ion-implanting one or more rare gases such as e with a doping amount of 1 × 10 ¹⁶ / cm ² or more. Manufacturing method of magnetic recording medium.