JP2000076647A - Magnetic recording medium and magnetic storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium capable of imparting magnetic characteristics optimum for high density in-plane magnetic recording to the magnetic layer, and to obtain a magnetic storage device having large capacity by using the medium. SOLUTION: An underlying layer 12 consisting of a nonmagnetic Ni-based alloy having a fcc structure is formed between a nonmagnetic substrate 11 and a Co-based alloy magnetic layer 13. In the layer 12, the (100) plane of the fcc structure is aligned along the normal line direction of the plate, and the Co-based alloy magnetic film 13 having a hcp structure is formed by epotaxially growing the (110) plane on the underlying layer.

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 magnetic storage device, and more particularly, to a magnetic recording medium in which information is recorded mainly by in-plane magnetization with respect to a film surface, and this magnetic recording medium. And a magnetic storage device using the same.

[0002]

2. Description of the Related Art As a prior art relating to a magnetic recording medium on which information is recorded mainly by in-plane magnetization on a film surface, a technology described in, for example, Japanese Patent Application Laid-Open No. 1-220217 is known. .

[0003] This prior art is based on a hard non-magnetic substrate.
5 having a body-centered cubic (100) plane parallel to the recording surface
0 to 200 Angstroms thick chrome (C
r) layer and (11) of a hexagonal close-packed structure formed by epitaxial growth on the (100) plane of the chromium layer.
0) and a cobalt alloy thin film having a c-axis parallel to the recording surface.

[0004]

In the above prior art, an ultra-thin Cr film is used as an underlayer and a cobalt alloy thin film is grown thereon. In general, the surface of the ultra-thin Cr film is active. Therefore, there is a problem that the coercive force varies greatly, it is difficult to grow a cobalt alloy thin film stably, and the process margin becomes small.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a hexagonal close-packed (hcp) structure (110) of a cobalt alloy film continuously formed on a nonmagnetic layer serving as an underlayer. An object of the present invention is to provide a magnetic recording medium having a cobalt-based alloy magnetic layer in which a (110) plane of an hcp structure is parallel to a recording surface by growing the surface stably.

Another object of the present invention is to provide a magnetic storage device using the magnetic recording medium.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to form a base layer made of a non-magnetic Ni-based alloy having a face-centered cubic structure on a hard non-magnetic substrate, and to form a cobalt-based alloy magnetic layer thereon. It is achieved by forming.

[0008] That is, the object is to form a base layer of a non-magnetic Ni-based alloy having a face-centered cubic (fcc) structure on a hard non-magnetic substrate by a high vacuum evaporation method or a sputtering method.
Raise the substrate temperature during film formation to 200 ° C or higher, and
A high-speed film formation of 300 nm is performed, and the film thickness is 20 to 90 nm.
Is formed so that the (100) plane is mainly the surface of the underlayer, and hcp is continuously formed on the surface of the underlayer.
This is achieved by epitaxially growing the (110) plane of the Co-based alloy magnetic layer having the structure.

[0009] These layers are formed by RF sputtering, DC
It can be formed by a sputtering method, a magnetron method as a cathode of an apparatus for executing these methods, or a thin film forming method by an ion beam sputtering method or the like to which a bias voltage is applied. .

In the above description, the reason why the high-speed film formation is performed by raising the substrate temperature to 200 ° C. or higher is to increase the mobility of atoms on the surface of the thin film at the time of film formation. This is because it is desirable to heat the plating film so as not to be magnetized.

As a pre-process for forming the magnetic film, it is preferable to previously roughen the surface of the underlying substrate by a processing technique generally called texture processing.
By providing fine scratches with a center line average surface roughness of 2 to 30 nm along the running direction of the magnetic head of the disk substrate, the non-magnetic metal underlayer on the disk substrate surface and the magnetic layer formed thereon The crystal grains of the layer can be oriented in the direction of travel of the magnetic head, and the squareness ratio in the direction of travel of the head,
Magnetic properties such as coercive force can be remarkably improved, and this texture effect contributes to improvement of magnetic properties in accordance with substrate heating at the time of forming a magnetic layer.

Another object of the present invention is to provide a magnetic recording medium having a magnetic recording medium, a driving unit for rotating the magnetic recording medium, a magnetic head and its driving means, and a recording / reproducing signal processing means for the magnetic head. In a storage device, this is achieved by forming the magnetic recording medium from an in-plane magnetic recording medium capable of achieving the above-described object of the present invention.

[0013]

In order to optimize a Co-based alloy magnetic thin film as an in-plane magnetic recording medium, it is necessary to orient the c-axis, which is the axis of easy magnetization of the Co-based alloy having the hcp structure, in the disk surface. For this purpose, it is necessary to grow the (hk0) plane of the Co alloy magnetic layer on the underlayer. Such a requirement is met by improving the lattice matching by making the (100) plane of the nonmagnetic Ni-based alloy underlayer having the fcc structure parallel to the recording surface, and improving the (110) plane of the Co alloy magnetic layer. Can be realized by epitaxial growth on the underlayer.

The nonmagnetic Ni-based alloy underlayer can be obtained as a (100) -oriented thin film by forming it under high vacuum evaporation or high-speed sputtering conditions. A Co-Ni-Cr alloy, Co-Pt
Alloy, Co-Cr-Pt alloy, Co-Cr-Ta alloy,
When a Co-based alloy magnetic film such as a Co-Cr-Ta-Pt alloy is formed, epitaxial growth can be performed such that the axis of easy magnetization (c-axis) is within the disk surface.

As a pre-process for forming a non-magnetic metal underlayer, a substrate undersurface made of Ni-P or the like is processed so as to have fine scratches substantially along the head traveling direction, and the center line roughness in the head traveling direction is formed. Ra is 1 to 10 nm, and Ra perpendicular to this is
Is set to 2 to 30 nm, the coercive force in the head traveling direction can be made larger than that in the radial direction, and the output can be increased by 10 to 20%. For Ra in the direction perpendicular to the head running direction, the effect is small unless it is 2 nm or more, and if it is larger than 30 nm, the sliding resistance is undesirably deteriorated.

The reason why the thickness of the underlayer is set to 20 to 90 nm is that when the thickness is smaller than 20 nm, the crystal grains of the underlayer are small and the crystal grain size of the magnetic film formed continuously is also reduced. Therefore, it becomes difficult to obtain a coercive force of 1200 Oe or more. On the other hand, if the film thickness exceeds 90 nm, for example, a (111) plane other than the (100) plane of the fcc structure tends to be formed on the base film surface. This is because it becomes difficult to obtain a coercive force of 1200 Oe or more.

That is, the thickness of the base film is set to 20 to 90 nm.
In this case, a crystal grain size large enough to obtain a coercive force of 1200 Oe or more can be obtained.
It is possible to form a (100) oriented base film superior to the (111) plane. Even with such an underlayer, if the lattice matching is shifted by 8% or more, hc containing at least one element selected from Ta or platinum is used.
Since the c-axis of a Co-based alloy having a p-structure is likely to be vertically oriented, the lattice matching needs to be within 8%, and more preferably within 4%, when selecting an alloy material for the base film.

The magnetic recording medium of the present invention is provided with Co-Nb-Zr, Fe-Al-Si, Ni-Fe
Recording and reproduction using a metal-in-gap type or thin-film magnetic head provided with a ferromagnetic metal such as above. If the in-plane coercive force in the disk circumferential direction is set to 1200 Oe or more, the reproduction output can be significantly improved. It was confirmed that it was possible. Further, when the in-plane coercive force is set to 1500 Oe, the output recording density characteristics can be further improved.

The magnetic head in which at least a part of the magnetic pole is made of the above-described metal magnetic material has good matching with the magnetic recording medium according to the present invention, and performs recording and reproduction using the magnetic head. By doing so, the efficiency can be improved and a large-capacity magnetic storage device can be provided.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the magnetic recording medium and magnetic storage device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a magnetic recording medium according to the present invention. In FIG. 1, reference numeral 11 denotes a substrate, 1
2, 12 'are underlayers, 13, 13' are magnetic layers, 14, 1
4 'is a protective coating film layer.

[Embodiment 1] In a first embodiment of the present invention, as shown in FIG.
2 ', magnetic layers 13, 13', protective coating layers 14, 14 '
These are formed by the following materials.

The substrate 11 is made of an Al—Mg alloy plated with Ni—P, Ni—WP, or the like, or an Al—Mg alloy treated with alumite.
It is formed of a Mg alloy, glass, ceramic, or the like.

The underlayers 12, 12 'are made of Ti, V, Nb,
Ta, Cr, Mo, Mn, Fe, Co, Cu, Al, S
It is formed of a nonmagnetic alloy in which at least one element selected from i is added to Ni.

The magnetic layers 13, 13 'are made of Co-Pt, Co
-Cr-Pt, Co-Ni-Pt, Co-Cr-Ta,
Co-Cr-Ta-Pt, Co-Ni-Cr, Co-C
It is formed of r-Ni-Pt or an alloy containing oxygen in these alloys.

The protective coating layers 14, 14 'are made of C, WM
It is formed of one of oxides of oC, B, boron carbide, silicon oxide, Rh, molybdenum disulfide, and an Al-Ta alloy. An organic lubricant layer may be further provided on the protective coating films 14 and 14 '.

Next, a method of forming a disk according to the first embodiment of the present invention will be described.

(1) A nonmagnetic Ni-12 wt% P plating layer having a thickness of 12 μm is formed on an Al alloy substrate having an outer diameter of 130 mm, an inner diameter of 40 mm, and a thickness of 1.9 mm.
Form one.

(2) Discharge A on the substrate 11 at a substrate temperature of 250 ° C. by RF magnetron sputtering.
r gas pressure 2 mTorr, RF input power 4 W / cm
^{In step 2} , an alloy target of Ni-28 wt% Mo-5 wt% Fe (Hastelloy B) was sputtered to a film thickness of 10
A non-magnetic underlayer 12 of 0, 50, 90 or 150 nm;
12 'is formed. Thereby, the underlayers 12 and 12 ′ are formed.
Is formed on the underlayer surface so as to have a (100) plane having a parallel face-centered cubic structure on the recording surface.

(3) Next, a film thickness of 60
The magnetic layers 13 and 13 'of a Co-12 at% Cr-4 at% Pt alloy having a thickness of 10 nm are formed on the underlayer by epitaxial growth. As a result, the magnetic layers 13, 13 '
Is formed such that the (110) plane of the hexagonal close-packed structure is parallel to the recording surface.

(4) Thereafter, protective coating layers 14 and 14 'made of C having a thickness of 30 nm are formed to form a magnetic disk.

When the coercive force Hc of the magnetic disk according to the first embodiment of the present invention was measured, when the thickness of the underlayers 12 and 12 'was set to 20 to 90 nm, Hc was set to 1200 Oe.
I was able to do above. On the other hand, when the thickness of the underlayer is 10 nm and 150 nm, Hc is 8
The value was as small as 60 Oe and 1080 Oe.

The reason why the value of Hc decreases when the thickness of the underlayer is 10 nm or 150 nm is that when the thickness of the underlayer is as thin as 10 nm, the crystal grains of the underlayers 12 and 12 ′ are fine. , The magnetic layers 13 and 13 ′ formed thereon
Is also finer, and the underlayer thickness is 15
When the thickness is as thick as 0 nm, it is the densest surface of the hcp structure (11
1) The surface is likely to be formed on the surface of the underlayer. This was clarified by magnetostatic property evaluation, scanning electron microscope observation, transmission electron microscope observation, and X-ray diffraction measurement.

The above effect is obtained when the lattice matching between the alloy composition used for the magnetic layers 13 and 13 'and the nonmagnetic Ni-based alloy used for the underlayers 12 and 12' is within 8%.
This was observed when the underlayers 12, 12 'were formed of a nonmagnetic Ni-based alloy such as Hastelloy C, Inconel, Alloy GDS, Alloy 20Cb3 (all trade names) as a sputter target.

[Embodiment 2] Next, a description will be given of a forming method according to a second embodiment of the present invention having a structure similar to the structure shown in FIG.

(1) A 15 μm non-magnetic Ni-11 wt% P plating layer is formed on the surface of an Al alloy substrate having an outer diameter of 130 mm, an inner diameter of 40 mm and a thickness of 1.27 mm.
Form one.

(2) On the non-magnetic substrate 11 formed above, using an in-line type DC magnetron sputtering apparatus, a substrate heating temperature of 200 ° C. and an Ar gas pressure of 3 mTorr.
r, input power 3 W / cm ² , and 50 nm thick Ni-1
7wt% Mo-16wt% Cr-4wt% W-5wt%
Non-magnetic underlayers 12 and 12 'made of an Fe alloy are formed.

(3) Next, a film thickness of 60
nm Co-10 at% Cr-4 at% Ta, Co-1
0 at% Cr-4 at% Pt or Co-9 at%
Cr-4 at% Ta-2 at% Pt alloy magnetic film 13,
13 'is formed.

(5) Thereafter, nonmagnetic protective coating layers 14 and 14 'made of C having a thickness of 25 nm are formed, and a solid lubricant is coated to a thickness of 4 nm to obtain a magnetic disk.

When the coercive force Hc of the magnetic disk according to the second embodiment of the present invention was measured, the coercive force was 1400 Oe or more in all cases.

FIGS. 2A and 2B are views for explaining the configuration of a magnetic storage device using the magnetic recording media according to the first and second embodiments of the present invention described above. FIG. 2A is a plan view, and FIG. FIG. In FIG. 2, 41 is a magnetic recording medium, 42 is a magnetic recording medium drive, 43 is a magnetic head, 44 is a magnetic head drive, and 45 is a recording / reproducing signal processing system.

The magnetic storage device shown in FIG. 2 uses the magnetic disk according to the first or second embodiment of the present invention as the magnetic recording medium 41, and incorporates one to nine magnetic recording media 41. A magnetic head 43 formed of a metal-in-gap type or a thin-film type using Fe-Al-Si-Ru or Co-Nb-Zr having a thickness of 2 m for a part of the magnetic core and a part of the magnetic core. It consists of. The disk unit is rotated by the magnetic recording medium driving unit 42, and the magnetic head 43 is
It is configured to be driven by the magnetic head driving unit 44.

The above-described magnetic storage device is 1.5 times smaller than a device using a magnetic recording medium formed by using a conventional magnetic recording medium such as a coating or a continuous medium made of a Co-Ni alloy. It is possible to record twice as much data.

[0044]

As described above, according to the present invention, it is possible to provide a magnetic layer with optimum magnetic characteristics for performing high-density in-plane magnetic recording, and a magnetic recording capable of storing a large capacity. A medium can be provided, and a large-capacity storage device can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a magnetic storage device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 12, 12 'Underlayer 13, 13' Magnetic layer 14, 14 'Protective coating layer 41 Magnetic recording medium 42 Magnetic recording medium drive 43 Magnetic head 44 Magnetic head drive 45 Recording / reproducing signal processing system

Claims (4)

[Claims] 1. A hard substrate, and Ti,
V, Nb, Ta, Cr, Mo, Mn, Fe, Co, C
an underlayer made of a nonmagnetic alloy obtained by adding at least one element selected from the group consisting of u, Al, and Si to Ni;
A magnetic recording medium comprising: a cobalt-based alloy magnetic layer provided on the underlayer. 2. The underlayer has a thickness of 20 to 90 n.
2. The magnetic recording medium according to claim 1, wherein m is m. 3. The magnetic recording medium according to claim 1, wherein the cobalt-based alloy magnetic layer contains at least one element selected from tantalum and platinum. 4. A magnetic storage device comprising a magnetic recording medium, a drive unit for rotating the magnetic recording medium, a magnetic head and its driving means, and a recording / reproducing signal processing means for the magnetic head. A magnetic storage device using the magnetic recording medium according to claim 1 as a medium.