JP2699312B2 - Magnetic recording medium and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording medium and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, magnetic recording materials have been used, for example, in thermomagnetic printers. In this case, a magnetic latent image is formed on a magnetic printer drum, and this is magnetically developed to obtain a visible image. ("Magnetography printer"
Shunji Imamura, edited by Shin Ohno, CMC "Non-impact printing", Chapter 15, P. 159-P. 168, 198
6).

FIG. 2 is a printing process diagram of a conventional thermomagnetic printer. In the figure, the recording magnetic drum 1 is indicated by an arrow A.
Rotate in the direction. On the surface of the recording magnetic drum 1, a CrO ₂ thin film as a magnetic recording medium for forming a magnetic latent image is provided. In the printing process, first, the demagnetizing means 2 magnetizes the magnetic recording medium in a certain direction. Next, the magnetic recording unit 3 forms a predetermined magnetic latent image, and the developing unit 4 deposits toner on the magnetic latent image, whereby the magnetic latent image is visualized. Here, the toner adheres to a portion of the magnetic recording medium surface where the magnetic field lines due to the leakage magnetic field intersect with the magnetic recording medium surface, and as a result, the magnetic latent image is visualized.

Thereafter, the transfer means 5 and the fixing means 6 transfer and fix the visible image on the sheet. Finally, the cleaning means 7 removes the residual toner on the magnetic recording medium, and ends the printing process. Incidentally, as a method of recording a magnetic latent image on the magnetic recording medium, there is a method using a thermal head or a method of heating by irradiating a laser beam.
The magnetization direction of the magnetic recording medium mainly includes a direction along the recording medium surface (in-plane recording method) and a direction perpendicular to the recording medium surface (perpendicular recording method). Uses a perpendicular recording method. The magnetic recording medium for perpendicular recording is formed of an alloy film of a rare earth element and an iron group element, that is, an RE-TM alloy film or a Co-Cr alloy film. The RE-TM alloy film is often used for a magneto-optical disk using a magneto-optical recording method, and the Co-Cr alloy film is often used for a magnetic disk using a magnetic head recording method.

Recently, thin films such as a Co / Pt artificial lattice film and a Co / Pd artificial lattice film, and films obtained by heat-treating these artificial lattice films in the atmosphere are also used as perpendicular magnetization films for thermomagnetic recording. Is available.

[0006]

However, in the magnetic recording medium having the above structure, when formed from a Co-Cr alloy film, thermomagnetic recording becomes difficult due to a high Curie temperature, and when formed from a RE-TM alloy film. However, since the residual magnetic flux density is small, the adhesion of the toner becomes insufficient. Also, Co
In the case of a / Pt artificial lattice film or a Co / Pd artificial lattice film, the square ratio of the magnetic hysteresis curve becomes smaller than 1 when the total film thickness is about several thousand degrees or more, and the residual magnetic flux density necessary for thermomagnetic recording can be obtained. And the coercive force is as small as about 200 Oe.

In the case where the artificial lattice film is subjected to a heat treatment in the air, the film is oxidized, so that a perpendicular magnetization film having a large coercive force and a large residual magnetic flux density can be obtained. In the case of forming, it is necessary to accurately control the heat treatment temperature and the heat treatment time in consideration of the thickness and the composition ratio of the film, and it is difficult to obtain predetermined magnetic characteristics. In addition, since the heat treatment is performed after the formation of the film, the time for forming the film is prolonged.

As described above, a thermomagnetic printer using a perpendicular magnetic film for perpendicular recording has high recording stability in principle, can obtain high resolution, and can be operated with low power consumption. However, there is no magnetic recording medium effective as a perpendicular magnetization film. The present invention solves the above-mentioned problems of the conventional magnetic recording medium, and can perform magnetic recording with a sufficiently high residual magnetic flux density, and has a sufficiently large coercive force and a sufficiently low Curie temperature. It is an object of the present invention to provide a magnetic recording medium for perpendicular recording capable of performing the following, and a method of manufacturing the same.

[0009]

For this purpose, in the magnetic recording medium of the present invention, an oxygen-Co / Pt artificial lattice film or an oxygen-Co / Pd artificial lattice film is formed on a substrate. Is the composition formula (Co / P
t) _100-X O X or (Co / Pd) and those represented by _{100 -X} O _X. At this time, the composition range is set so that 1 ≦ X ≦ 30.

Further, the Co layer thickness d _Co of the oxygen-Co / Pt artificial lattice film or the oxygen-Co / Pd artificial lattice film is 1Å ≦
d _Co ≦ 15 °, and the Pt layer thickness d _Pt or the Pd layer thickness d _Pd is 2
And Å ≦ d _Pt ≦ 30Å or 2Å ≦ d _Pd ≦ 30Å. When manufacturing the magnetic recording medium having the above configuration, a Co target and a Pt target (or a Pd target) are provided at an interval from the substrate, and the substrate is periodically moved to a position alternately facing the two targets. Put.

Then, high-frequency sputtering is performed in an atmosphere of a mixed gas containing at least oxygen, and an oxygen-Co / Pt artificial lattice film (or oxygen-Co / Pd) is formed on the substrate.
(Artificial lattice film).

[0012]

According to the present invention, a Co target and a Pt target (or a Pd target) are disposed at an interval from the substrate as described above, and the substrate is periodically moved to alternately oppose the two targets. Put in position. Then, the substrate is placed in an atmosphere of a mixed gas containing at least oxygen, and is subjected to sputtering.

In this way, the oxygen-Co / P
An artificial lattice film (or an oxygen-Co / Pd artificial lattice film) is formed. When X is atomic%, the composition formula (C
o / Pt) and those represented by _100-X O _X or _{(Co / Pd) 100-X} O X, the composition range is set such that 1 ≦ X ≦ 30. Further, the Co layer thickness d _{Co of the} oxygen-Co / Pt artificial lattice film or the oxygen-Co / Pd artificial lattice film is 1Å.
The Pt layer thickness d _Pt or the Pd layer thickness d _Pd is set to satisfy 2 ≦≦ d _Pt ≦ 30 ° or 2 ≦≦ d _Pd ≦ 30 ° so that ≦ d _Co ≦ 15 °.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a magnetic recording medium of the present invention, wherein FIG.
(B) is a sectional view of the recording magnetic drum. In the figure, a perpendicular magnetized film, that is, several tens to several hundreds, is formed on a bendable stainless steel substrate 8 having a thickness of several tens to several hundreds of microns by RF magnetron sputtering using a mixed gas of an inert substance, argon and oxygen. Oxygen with a micron thickness
Co / Pt artificial lattice film 10 is laminated on magnetic recording medium 1
1 is formed. The magnetic recording medium 11 is formed in a sheet shape and wound on a recording magnetic drum core 12.

FIG. 3 is a schematic view of a manufacturing apparatus to which the method for manufacturing a magnetic recording medium of the present invention is applied, and FIG.
(B) is the same top view. In the figure, reference numeral 21 denotes the rotating plate 2
2 is a substrate on which an artificial lattice film is formed by performing sputtering in an atmosphere of a mixed gas of argon and oxygen. Reference numeral 24 denotes a Co target disposed opposite the substrate 21, and reference numeral 25 denotes a Pt (or Pd) target similarly disposed opposite the substrate 21.

High frequency (RF) power supplies 26 and 27 for sputtering are connected between the Co target 24 and a Pt (or Pd) target 25 and the rotating plate 22.
Further, a partition plate 28 is provided between the Co target 24 and the Pt (or Pd) target 25. In the voltage application type RF multi-source sputtering apparatus having the above configuration, the rotating plate 2
As the substrate 2 rotates, the substrate 21 rotates on the Co target 24 and the Pt (or Pd) target 25, and Pt (or Pd) and Co are periodically laminated on the substrate 21, and oxygen -The Co / Pt artificial lattice film 10 is formed. Oxygen oxidizes a part of Co and Pt. At this time, the degree of oxidation of Co and Pt differs depending on conditions.

The sputtering conditions are as follows: background vacuum degree: P _BG = 2.0 × 10 ⁻⁶ Torr
r or less Mixed gas pressure of argon and oxygen: P _Ar = 3.0 × 10 ⁻³ T
orr Substrate temperature: room temperature Input power: frequency 300 to 700 W Further, the Co layer thickness d _Co of the oxygen-Co / Pt artificial lattice film 10 is 1Å ≦ d _Co ≦ 15 °, and the Pt layer thickness d _Pt is 2Å.
≦ d _Pt ≦ 30 °.

The oxygen-Co / Pt artificial lattice film 10 is represented by a composition formula of (Co / Pt) _100-X O _X , and its composition range is 1 ≦ X ≦ 30. However, (Co / P
t) is a Co / Pt artificial lattice film, and X is atomic%. FIG.
FIG. 3 is a diagram showing the relationship between the oxygen concentration in the oxygen-Co / Pt artificial lattice film and the oxygen partial pressure during sputtering.

Next, using the magnetic recording medium 11 having the above structure,
Of magnetic properties evaluation by thermomagnetic recording
explain. In this experiment, an oxygen-Co / Pt artificial lattice film was used.
The composition is (Co / Pt) as 10 ₉₀O_TenPerpendicular magnetization film
Use, Co layer thickness d_CoIs 5Å, Pt layer thickness d_PtIs 15Å
What was periodically laminated so as to be used was used. This magnetic record
When the recording medium 11 was evaluated, the coercive force was about 1300 Oe.
And the residual magnetic flux density is about 3000 Gauss.
Have sufficient magnetic force to absorb toner
You. The Curie temperature is about 200 ° C. or less.

Next, the magnetic recording medium 1 prepared under the above conditions
1 will be described with reference to FIGS. FIG.
FIG. 6 is a diagram showing a magnetization curve when the oxygen concentration in the film is 0% in the magnetic recording medium, and FIG. 6 is a diagram showing a magnetization curve when the oxygen concentration in the film is 10% in the magnetic recording medium.

It can be seen that the coercive force and the residual magnetic flux density are significantly increased. FIG. 7 is a diagram showing the relationship between the oxygen partial pressure and the magnetic characteristics when a film is formed by sputtering. When the oxygen partial pressure P _OX is 5 × 10 ⁻⁶ Torr or more, the magnetic properties are improved, and it can be seen that the coercive force and the residual magnetic flux density are maximum at 100 × 10 ⁻⁶ Torr.

Next, another embodiment of the present invention will be described. FIG. 8 is a diagram showing another magnetic recording medium of the present invention, in which (A) is a cross-sectional view of the magnetic recording medium, and (B) is a cross-sectional view of the recording magnetic drum. In the figure, a perpendicular magnetization film, that is, a film thickness of several tens to several hundreds of microns, is formed on a bendable stainless steel substrate 8 having a thickness of several tens to several hundreds of microns by using an RF magnetron sputtering method with a mixed gas of argon and oxygen. The magnetic recording medium 14 is formed by laminating the oxygen-Co / Pd artificial lattice film 13 having The magnetic recording medium 14 is formed in a sheet shape and wound around the recording magnetic drum core 12.

Oxygen-Co / Pd artificial lattice film 1 having the above structure
3 is formed by the manufacturing apparatus and the manufacturing method shown in FIG. The conditions for sputtering are the same. The Co layer thickness d _Co of the oxygen-Co / Pd artificial lattice film 13 is 1Å
≦ d _Co ≦ 15 ° and the Pd layer thickness d _Pd is 2 ≦≦ d _Pd ≦ 3
0 °. The oxygen-Co / Pd artificial lattice film 13 is represented by a composition formula of (Co / Pd) _100-X O _X , and the composition range is 1 ≦ X ≦ 30. However, (Co / P
d) is a Co / Pd artificial lattice film, and X is atomic%. The relationship between the oxygen concentration in the film and the oxygen partial pressure P _OX during sputtering is similar to that of the oxygen-Co / Pt artificial lattice film 10 described above.

Next, using the magnetic recording medium 14 having the above configuration,
Of magnetic properties evaluation by thermomagnetic recording
explain. In this experiment, an oxygen-Co / Pd artificial lattice film was used.
The composition is (Co / Pd) as 13 ₉₀O_TenPerpendicular magnetization film
Use, Co layer thickness d_CoIs 5Å, Pd layer thickness d_PdIs 15Å
What was periodically laminated so as to be used was used. This magnetic record
When the recording medium 14 was evaluated, the coercive force was about 2000 Oe.
And the residual magnetic flux density is about 3000 Gauss.
Have sufficient magnetic force to absorb toner
You. The Curie temperature is about 200 ° C. or less.

Next, the magnetic recording medium 1 prepared under the above conditions
4 will be described with reference to FIGS. 9 and 10. FIG. FIG. 9 is a diagram showing a magnetization curve when the oxygen concentration in the film is 0% in another magnetic recording medium, and FIG. 10 is a magnetization curve when the oxygen concentration in the film is 10% in another magnetic recording medium. FIG.

It can be seen that the coercive force and the residual magnetic flux density are significantly increased. FIG. 11 is a diagram showing the relationship between the oxygen partial pressure and the magnetic properties when a film is formed by sputtering. Oxygen partial pressure P _OX
Is greater than 5 × 10 ^-6 Torr, the magnetic properties are improved, and it can be seen that the coercive force and the residual magnetic flux density are maximum at 100 × 10 ^-6 Torr.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and these are not excluded from the scope of the present invention. For example, in the above embodiment, a thermomagnetic printer is shown as an example in which the magnetic recording media 11 and 14 are applied, but the present invention can also be applied to other recording devices that perform recording by irradiation of heat and light.

The total thickness of the perpendicular magnetization film is set to several tens to several hundreds of microns, and the plate thickness of the stainless steel substrate 8 is set to several tens to several hundreds of microns. These thicknesses may be changed according to the application. Can be.

[0029]

As described above in detail, according to the present invention, a Co target and a Pt target (or Pd target) are arranged at an interval from a substrate, and sputtering is performed in an atmosphere of a mixed gas containing at least oxygen. Is applied. In this way, an oxygen-Co / Pt artificial lattice film (or oxygen-Co / Pd artificial lattice film) is formed on the substrate, and the film has a composition formula (Co / P
t) and _100-X O _X or (Co / Pd) those represented by _100-X O X, the composition range is set such that 1 ≦ X ≦ 30, also, Co layer thickness d _Co is 1 Å ≦ d _The Pt layer thickness d _Pt or the Pd layer thickness d _Pd is 2Å ≦ d _Pt ≦ such that _Co ≦ 15 °.
30 ° or 2 ° ≦ d _Pd ≦ 30 °, so that not only high magnetic recording density can be obtained but also coercive force and residual magnetic flux density increase in the thermomagnetic recording method for performing perpendicular recording. . In addition, since it is only necessary to use a mixed gas containing at least oxygen when forming the film, the method for manufacturing the film is simplified.

When this is used in a thermomagnetic printer, for example, the resolution can be increased and the power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a magnetic recording medium of the present invention.

FIG. 2 is a printing process diagram of a conventional thermomagnetic printer.

FIG. 3 is a schematic diagram of a manufacturing apparatus to which a method for manufacturing a magnetic recording medium according to the present invention is applied.

FIG. 4 is a diagram showing the relationship between the oxygen concentration in an oxygen-Co / Pt artificial lattice film and the oxygen partial pressure during sputtering.

FIG. 5 is a diagram showing a magnetization curve when the oxygen concentration in a film in a magnetic recording medium is set to 0%.

FIG. 6 shows that the oxygen concentration in the film of the magnetic recording medium is 10%.
It is a figure which shows the magnetization curve when it is set as.

FIG. 7 is a diagram illustrating a relationship between an oxygen partial pressure and magnetic characteristics when a film is formed by sputtering.

FIG. 8 is a diagram showing another magnetic recording medium of the present invention.

FIG. 9 shows that the oxygen concentration in a film of another magnetic recording medium is set to 0.
It is a figure which shows the magnetization curve when it is set to%.

FIG. 10 is a diagram showing a magnetization curve when the oxygen concentration in the film is 10% in another magnetic recording medium.

FIG. 11 is a diagram showing a relationship between an oxygen partial pressure and magnetic characteristics when a film is formed by sputtering.

[Explanation of symbols]

 Reference Signs List 8 stainless steel substrate 10 oxygen-Co / Pt artificial lattice film 11, 14 magnetic recording medium 12 core of magnetic drum for recording 13 oxygen-Co / Pd artificial lattice film 21 substrate 22 rotating plate 24 Co target 25 Pt (or Pd) target 26 , 27 High frequency (RF) power supply 28

Claims (6)

(57) [Claims] 1. An oxygen-Co / Pt artificial lattice film formed on (a) a substrate and (b) an oxygen-Co / Pt artificial lattice film formed on the substrate. _{Pt) 100-X O X (} Co / Pt): Co / Pt artificial lattice film X: represented by atomic% a composition formula, a magnetic recording medium, characterized in that the composition range is 1 ≦ X ≦ 30. 2. The magnetic recording according to claim 1, wherein the Co-layer thickness d _Co of the oxygen-Co / Pt artificial lattice film is 1 ° ≦ d _Co ≦ 15 °, and the Pt layer thickness d _Pt is 2 ° ≦ d _Pt ≦ 30 °. Medium. (A) a Co target and a Pt target are provided at an interval from the substrate; (b) the substrate is periodically moved and placed at a position alternately opposite to the two targets; Sputtering is performed in an atmosphere of a mixed gas containing at least oxygen, and oxygen-Co / P
A method for manufacturing a magnetic recording medium for forming an artificial lattice film. 4. An artificial lattice film comprising (a) a substrate and (b) an oxygen-Co / Pd artificial lattice film formed on the substrate, and (c) the oxygen-Co / Pd artificial lattice film comprises (Co / _{Pd) 100-X O X (} Co / Pd): Co / Pd artificial lattice film X: represented by atomic% a composition formula, a magnetic recording medium, characterized in that the composition range is 1 ≦ X ≦ 30. 5. The magnetic recording according to claim 4, wherein the Co layer thickness d _Co of the oxygen-Co / Pd artificial lattice film is 1 ° ≦ d _Co ≦ 15 °, and the Pd layer thickness d _Pd is 2 ° ≦ d _Pd ≦ 30 °. Medium. (A) a Co target and a Pd target are provided at an interval from the substrate; (b) the substrate is periodically moved and placed at a position alternately opposite to the two targets; Sputtering is performed in an atmosphere of a mixed gas containing at least oxygen, and oxygen-Co / P
d Manufacturing method of magnetic recording medium for forming artificial lattice film.