JPH05266454A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance recording and reproducing characteristics by forming a perpendicular recording layer having high coercive force, high residual magnetization and magnetically excellent perpendicular orienting property on a soft magnetic backing layer made of an NiFe film. CONSTITUTION:This perpendicular magnetic recording medium has a two-layered film structure formed by successively laminating a soft magnetic backing layer 12 and a perpendicular recording layer on a discoid nonmagnetic substrate 11. The perpendicular recording layer has a two-layered structure formed by laminating a first recording magnetic film 21 having high coercive force and magnetically excellent perpendicular orienting property from the initially grown layer and a second recording magnetic film 22 made of a CoCr film on the soft magnetic backing layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perpendicular magnetic recording medium used in a perpendicular magnetic recording type magnetic disk device, and more particularly to a perpendicular magnetic recording medium having a double-layer structure suitable for high density recording.

In recent years, as the amount of information processing in a computer system has increased, the amount of information recorded on a magnetic disk device has also increased, which has led to a reduction in size and capacity, and a demand for higher recording density.

Accordingly, in the magnetic recording medium, a perpendicular magnetization recording type recording medium, which enables higher density recording than a conventional horizontal magnetization recording type recording medium, that is,
A perpendicular magnetic recording medium having a two-layer film structure in which a perpendicular recording layer having perpendicular magnetic anisotropy is laminated on a soft magnetic backing layer having a high magnetic permeability has been proposed and put into practical use.

In such a perpendicular magnetic recording medium, the coercive force of the initial growth layer of the perpendicular recording layer made of the CoCr film formed on the soft magnetic backing layer is small, and the perpendicular magnetic orientation is poor, so that the recording / reproducing characteristics are Tend to deteriorate. Therefore, there is a need for a medium structure that enhances the coercive force and perpendicular magnetic orientation of the initial growth layer of such a perpendicular recording layer to improve the recording / reproducing characteristics.

[0005]

2. Description of the Related Art Conventionally, a coating type magnetic recording medium in which a magnetic powder mixed with a binder is coated on a non-magnetic substrate such as aluminum has been widely used, and thereafter, a continuous thin film by a sputtering method which enables higher density recording. Magnetic recording media have come into use. However, in the horizontal magnetization recording method in which the magnetization is left in the horizontal direction of the magnetic recording film for recording, as the recording density increases, the effect of self-demagnetization of the recording magnetization becomes stronger and the reproduction output decreases, limiting the high density recording. Will occur.

Therefore, even in high density recording, a perpendicular recording method has been proposed in which there is no self-demagnetization of the recording magnetization, and moreover, the magnetization is left in the perpendicular direction of the magnetic recording film, and development for practical use is underway.

Such a conventional perpendicular magnetic recording medium having a double-layered film structure is formed on a non-magnetic substrate 11 made of an aluminum disk having a surface treatment such as NiP plating as shown in the sectional view of the main part of FIG. , A high magnetic permeability soft magnetic backing layer 12 and 0.13 made of, for example, a NiFe film having a thickness of 1 μm by a sputtering method.
The perpendicular recording layer 13 made of a CoCr film having a thickness of μm is laminated, and the surface of the perpendicular recording layer 13 is covered with a lubrication protective film 14 if necessary.

A recording magnetic field from a perpendicular magnetic head for recording / reproducing with respect to the perpendicular magnetic recording medium having this structure is perpendicularly magnetized and passes through the perpendicular recording layer 13, and the soft magnetic backing layer 12 immediately thereunder. And the vertical recording layer 13
Information is recorded by a magnetic circuit that passes through the magnetic recording medium perpendicularly to the perpendicular magnetic head side and returns to the side of the perpendicular magnetic head, and the main magnetic pole of the perpendicular magnetic head that has already received the recording magnetic field from the perpendicular recording layer 13 is magnetized. The reproduction is performed by extracting the voltage generated in the coil interlinking with the main magnetic pole as a reproduction signal.

[0009]

By the way, in the perpendicular magnetic recording medium having the above-mentioned two-layer film structure, the non-magnetic substrate 11 is formed.
When a perpendicular recording layer made of a CoCr film is formed on the soft magnetic backing layer 12 made of a NiFe film by a sputtering method, Co
A growth initial layer of about 40 to 50 nm is required to grow and form a complete CoCr film with a ratio of 80 at% and 20 at% of Cr, and the coercive force of this initial growth layer is small, and the magnetic perpendicular Due to the poor orientation, there is a problem that the recording and reproducing characteristics are deteriorated such that the writability and reproduction output of the magnetic recording medium are lowered.

On the other hand, in order to solve such a problem,
It has been found that by providing a perpendicular recording layer on the soft magnetic underlayer via a Ti layer, the coercive force and perpendicular magnetic orientation of the initial growth layer of the perpendicular recording layer are improved. There is. However, the interposition of such a non-magnetic Ti layer increases the gap between the soft magnetic backing layer and the magnetic pole tip of the perpendicular magnetic head during recording / reproducing by the thickness of the recording layer. The loss will increase,
There is a problem that the magnetic properties of the initial growth layer improved by the gap loss are largely offset.

As another example, the soft magnetic backing layer 12
A medium structure is formed by stacking a perpendicular recording layer made of a 0.13 μm thick CoCrTa film (Co: 78 at%, Cr: 17 at%, Ta: 5 at%) in which a third element such as Ta is added to CoCr. As a result, the magnetic properties of the initial growth layer of the perpendicular recording layer can be improved. However, the addition of the third element relatively reduces the amount of Co contributing to the remanent magnetization. There is a problem that the amount decreases and the output decreases.

A perpendicular magnetic recording medium having a perpendicular recording layer made of such a CoCrTa film is described in, for example, Masayuki S.
B-in the paper by J.Appl.Phys.67 (10), 15 May 1990 by agoi et al.
It is described that the angularity of the H loop is good, the coercive force Hc⊥ in the vertical direction is high, and the index Δθ ₅₀ showing the crystallographic vertical orientation is small.

The present invention has been made in consideration of the above-mentioned conventional problems.
A new perpendicular magnetic recording medium with improved recording and reproducing characteristics is provided on a soft magnetic backing layer made of an Fe film by providing a perpendicular recording layer with high coercive force, high remanent magnetization and excellent magnetic perpendicular orientation. It is intended to be provided.

[0014]

In order to achieve the above-mentioned object, the present invention has a perpendicular magnetic layer having a two-layer film structure in which a soft magnetic backing layer and a perpendicular recording layer are sequentially laminated on a disk-shaped non-magnetic substrate. In the recording medium, the perpendicular recording layer has a two-layer structure in which a first recording magnetic film and a second recording magnetic film are laminated from the soft magnetic backing layer side.

Further, the film thickness t ₁ of the first recording magnetic film forming the perpendicular recording layer is equal to or smaller than the film thickness t ₂ of the second recording magnetic film, and the film thickness of the first recording magnetic film is t ₁ . The film thickness t ₁ is
The configuration is 50 nm or less.

Further, the first recording magnetic film forming the perpendicular recording layer is made of a CoCrTa film or a CoCrPt film, and the second recording magnetic film is made of a CoCr film.

[0017]

According to the present invention, a soft magnetic backing layer made of a NiFe film provided on a disk-shaped non-magnetic substrate is used as a perpendicular recording layer from a very thin initial growth layer to a high coercive force and excellent magnetic perpendicularity. Thin film CoCrTa with orientation
Film or first recording magnetic film made of CoCrPt and its first
By providing the second recording magnetic layer made of a thick Co-Cr film on the recording magnetic film, the second recording magnetic film also has a high coercive force from the initial growth layer and has excellent magnetic vertical orientation. Since the second recording magnetic film has a large remanent magnetization and a large film thickness, the entire perpendicular recording layer composed of these films has a high coercive force, a high remanent magnetization, and a high vertical alignment property. It is possible to obtain a perpendicular magnetic recording medium with improved magnetic recording / reproducing characteristics without the interposition of an intermediate film made of Ti which causes a gap loss.

[0018]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of an essential part showing an embodiment of a perpendicular magnetic recording medium according to the present invention.

In the figure, reference numeral 11 denotes a non-magnetic substrate 11 made of an aluminum disk which is provided with a support hole at the center and which has been subjected to surface treatment such as NiP plating.
For example, a high-permeability soft magnetic backing layer 12 made of a NiFe film having a thickness of 1 μm is provided, and a first recording magnetic film 21 made of a CoCrTa film having a thickness of 0.04 μm is formed as a perpendicular recording layer on the soft magnetic backing layer 12. And a second recording magnetic film 22 made of a CoCr film having a film thickness of 0.09 μm are laminated. The surface of the second recording magnetic film 22 is covered with a lubrication protective film 14 if necessary.

By using the perpendicular magnetic recording medium having such a structure, the perpendicular recording layer provided on the soft magnetic backing layer made of a NiFe film has a very thin initial growth layer, a high coercive force, and an excellent magnetic property. Second recording magnetic film 22 by providing a second recording magnetic film 22 made of a thick CoCr film on a first recording magnetic film made of a thin CoCrTa film having a vertical orientation. Also becomes a film having high magnetic coercive force and excellent magnetic vertical orientation from the initial growth layer, and the second recording magnetic film 22 has a large residual magnetization and a large film thickness. As a result, a film having high coercive force, high remanent magnetization, and high vertical orientation is obtained.

Therefore, it is possible to obtain a perpendicular magnetic recording medium with improved magnetic recording / reproducing characteristics without interposing an intermediate film such as Ti which causes a gap loss between the soft magnetic backing layer and the perpendicular recording layer as in the conventional case. it can.

As a method of manufacturing the perpendicular magnetic recording medium having the above-mentioned structure, the power density of the power supplied for sputtering is 5.5 W / cm ² , the sputtering gas pressure is 1 mTorr, and the substrate temperature is on the non-magnetic substrate 11. The soft magnetic backing layer 12 made of a NiFe film with a thickness of 1 μm is formed by a sputtering method under the sputtering conditions of 200 ° C., and the soft magnetic backing layer 12 is sputtered under the same sputtering conditions as above. Method, a perpendicular recording layer with a film thickness of 0.04 μm
The first recording magnetic film 21 made of CoCrTa film and the film thickness of 0.09 μm
A second recording magnetic film 22 made of a CoCr film is formed in a laminated shape,
Furthermore, by coating the surface of the second recording magnetic film 22 with a lubricating protective film 14 such as a sputtered carbon film, if desired, the desired perpendicular magnetic recording medium shown in FIG. 1 can be obtained.

The Co used as the first recording magnetic film is
The ratio of each contained element in the CrTa film is Co: 78at%, Cr: 17at
%, Ta: 5 at%, and a similar effect can be obtained by using a CoCrPt film instead of the CoCrTa film.

Furthermore, in this embodiment, an example in which the soft magnetic backing layer made of a NiFe film is provided by the sputtering method has been described, but a plating method or another method may be used.
Needless to say, the soft magnetic backing layer is not limited to the NiFe film, and a soft magnetic film such as a CoZrNb film or a FeN film may be used.

Table 1 shows a perpendicular magnetic recording medium of the present invention (this embodiment), a soft magnetic backing layer 12 made of a NiFe film having a thickness of 1 μm and a CoCr film having a thickness of 0.13 μm on a non-magnetic substrate 11. Conventional perpendicular magnetic recording medium in which a perpendicular recording layer 13 composed of
(Prior art example) and a conventional perpendicular magnetic recording medium in which a soft magnetic backing layer made of a NiFe film having a thickness of 1 μm and a perpendicular recording layer made of a CoCrTa film having a thickness of 0.13 μm are laminated on a non-magnetic substrate.
The results of measuring the magnetic characteristics such as the coercive force and the saturation magnetic flux density of (Comparative Example) with a sample vibration type magnetometer (VSM) are shown.

[0026]

[Table 1]

As is clear from Table 1, the perpendicular magnetic recording medium of the present invention has a higher coercive force than the conventional example and the comparative example, and a saturation magnetic flux density slightly lower than that of the conventional example. Higher values, higher coercive force,
It was confirmed that the recording medium had a high saturation magnetic flux density.

[0028]

As is apparent from the above description, according to the perpendicular magnetic recording medium of the present invention, the perpendicular recording layer provided on the high magnetic permeability soft magnetic backing layer has a high coercive force from the initial growth layer. And a structure in which a first recording magnetic film made of a thin CoCrTa film or the like having excellent magnetic vertical orientation and a second recording magnetic film made of a thick CoCr film are laminated. As a result, a film with high coercive force, high vertical orientation and high remanence can be obtained as the entire perpendicular recording layer of this two-layer structure, and these magnetic characteristics can be improved without the presence of an intermediate layer that causes gap loss. Therefore, it becomes possible to obtain a perpendicular magnetic recording medium having excellent magnetic recording and reproducing characteristics.
The practical effect is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a perpendicular magnetic recording medium of the present invention.

FIG. 2 is a sectional view of relevant parts for explaining a conventional perpendicular magnetic recording medium.

[Explanation of symbols]

 11 Non-Magnetic Substrate 12 Soft Magnetic Backing Layer 14 Lubrication Protecting Film 21 First Recording Magnetic Film (CoCrTa) 22 Second Recording Magnetic Film (CoCr)

Claims (3)

[Claims] 1. A soft magnetic backing layer (12) on a non-magnetic substrate (11).
A perpendicular magnetic recording medium having a two-layer film structure in which a magnetic recording layer and a perpendicular recording layer are sequentially laminated, wherein the perpendicular recording layer comprises a first recording magnetic film (21) and A perpendicular magnetic recording medium having a two-layer structure in which two recording magnetic films (22) are laminated. Wherein between the film thickness t ₂ of the thickness t ₁ and the second recording magnetic layer of the first recording magnetic film of the perpendicular recording layer (21) (22),
The first recording magnetic film having a relationship of t ₂ / t ₁ ≧ 1
The perpendicular magnetic recording medium of claim 1, wherein the thickness t ₁ is 50nm or less (21). 3. A first recording magnetic film forming the perpendicular recording layer.
2. The first recording magnetic film (22) is a CoCr film and the second recording magnetic film (22) is a CoCrTa film or a CoCrPt film.
Perpendicular magnetic recording medium.