JPH04291017A - Magnetic recording medium and magnetic memory device - Google Patents

Abstract

PURPOSE:To provide the recording medium constituted to apply the magnetic characteristics optimum for high-density intra-surface magnetic recording to magnetic layers thereby obtaining the magnetic memory device of a large capacity. CONSTITUTION:A substrate 12 consisting of a nonmagnetic Ni-based alloy having an fcc structure is provided between a nonmagnetic substrate 11 and the magnetic layer 13 consisting of a Co-based alloy. The substrate 12 is formed by orienting the 100 face of the fcc structure in the direction normal to the film plane and the magnetic film 13 consisting of the Co-based alloy is formed by epitaxially growing the 110 face on the above-mentioned substrate.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] 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 magnetization in the in-plane direction with respect to the film surface, and this magnetic recording medium. This invention relates to a magnetic storage device using.

0002

BACKGROUND OF THE INVENTION As a prior art related to a magnetic recording medium in which information is recorded mainly by magnetization in the in-plane direction on a film surface, for example, the technology described in Japanese Patent Application Laid-Open No. 1-220217 is known. .

[0003] This conventional technology has a hard non-magnetic substrate on which
5 with a body-centered cubic structure (100) plane parallel to the recording surface
Chromium (Cr) with a thickness of 0 to 200 angstroms
) layer and a (110) hexagonal close-packed structure formed by epitaxial growth on the (100) plane of the chromium layer.
A cobalt alloy thin film having a surface and a c-axis parallel to the recording surface is provided.

0004

[Problems to be Solved by the Invention] The above-mentioned prior art uses an ultra-thin Cr film as an underlayer and grows a cobalt alloy thin film thereon, but generally the surface of the ultra-thin Cr film is not active. Therefore, there are problems in that the coercive force varies widely, and it is difficult to stably grow a cobalt alloy thin film, resulting in a small process margin.

An object of the present invention is to solve the problems of the prior art, and to provide a (110) hexagonal close-packed (hcp) structure of a cobalt alloy film continuously formed on a non-magnetic layer serving as an underlayer. The object of the present invention is to provide a magnetic recording medium having a cobalt-based alloy magnetic layer in which the plane is stably grown and the (110) plane of the hcp structure is parallel to the recording plane.

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

[0007]

[Means for Solving the Problems] An object of the present invention is 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. This is achieved by forming.

That is, the above object is to form an underlayer of a nonmagnetic Ni-based alloy having a face-centered cubic (FCC) structure on a hard nonmagnetic substrate by high vacuum evaporation or sputtering.
Raise the substrate temperature to 200℃ or higher during film formation, and increase the speed at 80℃ per minute
300nm high-speed film formation, film thickness 20-90nm
By doing so, the (100) plane is formed as the surface of the underlayer, and hcp is continuously formed on the surface of this underlayer.
This is achieved by epitaxially growing the (110) plane of a Co-based alloy magnetic layer having a structure.

[0009] These layer structures can be formed using RF sputtering, DC
It can be formed by either a sputtering method, a thin film forming method using a magnetron method for the cathode of a device that executes these methods, or an ion beam sputtering method using a bias voltage applied. .

[0010] In the above, the reason why the substrate temperature is raised to 200°C or higher to perform high-speed film formation is to increase the mobility of atoms on the thin film surface during film formation. This is because it is desirable to heat the plated film so that it does not become magnetized.

[0011] As a pre-process for forming the magnetic film, it is preferable to roughen the surface of the base substrate in advance using a processing technique generally called texturing.
By creating fine scratches with a center line average surface roughness of 2 to 30 nm along the running direction of the magnetic head on the disk substrate, the non-magnetic metal underlayer on the surface of the disk substrate and the magnetic properties formed thereon are The crystal grains of the layer can be oriented in the running direction of the magnetic head, and the squareness ratio in the head running direction can be improved.
Magnetic properties such as coercive force can be significantly improved, and this texture effect contributes to improvement of magnetic properties in accordance with substrate heating during formation of the magnetic layer.

Another object of the present invention is to provide a magnetic recording medium comprising a magnetic recording medium, a driving section for rotationally driving the magnetic recording medium, a magnetic head and its driving means, and a recording/reproducing signal processing means for the magnetic head. This is achieved by configuring the magnetic recording medium in the storage device as a longitudinal magnetic recording medium that can achieve the above-described object of the present invention.

[0013]

[Operation] In order to optimize the 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 an hcp structure, within the disk plane. For this purpose, it is necessary to grow the (hk0) plane of the Co alloy magnetic layer on the surface of the underlayer. These requirements can be met by improving lattice matching by making the (100) plane of the non-magnetic Ni-based alloy underlayer parallel to the recording surface, and by making the (110) plane of the Co alloy magnetic layer parallel to the recording surface. This can be realized by epitaxially growing on the base layer.

[0014] The nonmagnetic Ni-based alloy underlayer can be obtained as a thin film mainly oriented in (100) by forming it under high vacuum evaporation or high speed sputtering conditions. Co-Ni-Cr alloy, Co-Pt alloy, Co-Cr-Pt alloy, Co-Cr-Ta alloy, C
When a Co-based alloy magnetic film such as an o-Cr-Ta-Pt alloy is formed, it becomes possible to perform epitaxial growth such that the axis of easy magnetization (c-axis) lies within the disk plane.

As a pre-process for forming the non-magnetic metal underlayer, the surface of the Ni--P substrate underlayer is processed so that fine scratches are formed approximately along the head running direction, and the center line roughness in the head running direction is By setting Ra to 1 to 10 nm and Ra in the direction perpendicular to this to 2 to 30 nm, the coercive force in the head running direction can be made larger than that in the radial direction, and the output can be increased by 10 to 20%. can. Regarding Ra in the direction perpendicular to the head running direction, if it is not 2 nm or more, the effect will be small, and if it is larger than 30 nm, the sliding resistance will deteriorate, which is not preferable.

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

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

The magnetic recording medium of the present invention has Co-Nb-Zr, Fe-Al-Si, Ni-Fe near the working gap.
When recording and reproducing using a metal-in-gap type or thin-film magnetic head equipped with ferromagnetic metal such as It has been confirmed that this is possible. Further, by setting the in-plane coercive force to 1500 Oe, the output recording density characteristics can be further improved.

A magnetic head in which at least a part of the magnetic pole is made of the metal magnetic material as described above has good compatibility with the magnetic recording medium according to the present invention, and is used for recording and reproducing. By doing so, efficiency can be improved and a large capacity magnetic storage device can be provided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a magnetic recording medium and a magnetic storage device according to the present invention will be explained in detail with reference to the drawings.

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

[Embodiment 1] In the first embodiment of the present invention, as shown in FIG.
', magnetic layers 13, 13', and protective coating layers 14, 14', which are made of the following materials.

The substrate 11 is made of an Al-Mg alloy plated with Ni-P, Ni-W-P, etc., or an Al-Mg alloy plated with anodized aluminum.
It is formed from Mg alloy, glass, ceramics, etc.

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

The magnetic layers 13 and 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 of these containing oxygen.

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

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

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

(2) On this substrate 11, a discharge A is applied at a substrate temperature of 250° C. by RF magnetron sputtering method.
Ni-28wt%Mo-5wt%Fe (Hastelloy B
) alloy target was sputtered, and the film thickness was 10, 20, 5.
0, 90 or 150 nm non-magnetic underlayer 12, 12'
form. As a result, the underlayers 12 and 12' have a (100) face-centered cubic structure parallel to the recording surface on the surface of the underlayer.
It is formed to have a surface.

(3) Next, in the same manner as described above, the film thickness was set to 60
Magnetic layers 13 and 13' made of Co-12at%Cr-4at%Pt alloy with a thickness of 100 nm are formed by epitaxial growth on the underlayer. As a result, the magnetic layers 13 and 13' are formed so that the (110) plane of the hexagonal close-packed structure is parallel to the recording surface.

(4) Thereafter, a protective coating layer 14, 14' made of C and having a thickness of 30 nm is 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, it was found that when the thickness of the underlayers 12 and 12' was 20 to 90 nm, Hc was 1200 Oe.
I was able to do more than that. On the other hand, when the underlying layer thickness is 10 nm and 150 nm, Hc is 8 nm and 150 nm, respectively.
The values were small at 60 Oe and 1080 Oe.

[0033] The reason why the value of Hc becomes small when the thickness of the base layer is 10 nm and 150 nm is that when the thickness of the base layer is as thin as 10 nm, the crystal grains of the base layers 12 and 12' are fine. , magnetic layers 13, 13' formed thereon
The crystal grains are also made finer, so the thickness of the base film is 15
When it is as thick as 0 nm, it is the most densely packed plane of the hcp structure (11
1) This is because surfaces tend to form on the surface of the base layer. This was revealed by magnetostatic property evaluation, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements.

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

[Embodiment 2] Next, a method of forming a second embodiment of the present invention having a structure similar to that shown in FIG. 1 will be described.

(1) A nonmagnetic substrate 1 is formed by forming a 15 μm nonmagnetic Ni-11wt%P plating layer on the surface of an Al alloy substrate with an outer diameter of 130 mm, an inner diameter of 40 mm, and a thickness of 1.27 mm.
form 1.

(2) On the non-magnetic substrate 11 formed above, using an in-line type DC magnetron sputtering device, a substrate heating temperature of 200° C., an Ar gas pressure of 3 mTorr,
Ni-17w with a film thickness of 50 nm at an input power of 3 W/cm2
t%Mo-16wt%Cr-4wt%W-5wt%Fe
Nonmagnetic underlayers 12 and 12' made of an alloy are formed.

(3) Next, in the same manner as described above, the film thickness was set to 60
nm Co-10at%Cr-4at%Ta, Co-1
0at%Cr-4at%Pt or Co-9at%
Cr-4at%Ta-2at%Pt alloy magnetic film 13,
13' is formed.

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

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

FIG. 2 is a diagram illustrating the configuration of a magnetic storage device using magnetic recording media according to the first and second embodiments of the present invention, in which (a) is a plan view and (b) is a cross-sectional view. It is a diagram. In FIG. 2, 41 is a magnetic recording medium, 42 is a magnetic recording medium drive section, 43 is a magnetic head, 44 is a magnetic head drive section, and 45 is a recording/reproducing signal processing system.

The magnetic storage device shown in FIG. 2 uses the above-described magnetic disk according to the first or second embodiment of the present invention as a magnetic recording medium 41, and incorporates one to nine magnetic recording media 41. The magnetic head 43 is formed into a metal-in-gap type or thin-film type using Fe-Al-Si-Ru with a thickness of 2 μm or Co-Nb-Zr with a thickness of 16 μm for the disk portion and a part of the magnetic core. It is made up of. The disk unit is rotationally driven by a magnetic recording medium drive unit 42, and the magnetic head 43 is
It is configured to be driven by a magnetic head drive section 44.

The above-mentioned magnetic storage device has a magnetic storage capacity of 1.5% compared to a device using a magnetic recording medium constructed using a conventional coating such as a coating, a continuous medium made of a Co--Ni alloy, or the like. It is possible to record more than double the capacity.

[0044]

Effects of the Invention As explained above, according to the present invention, it is possible to provide the magnetic layer with optimal magnetic properties for performing high-density in-plane magnetic recording, and magnetic recording that enables large-capacity storage. Media can be provided and mass storage can be provided.

[Brief explanation of the drawing]

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

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

[Explanation of symbols]

11 Board 12, 12' Base layer 13, 13' Magnetic layer 14, 14' Protective coating layer 41 Magnetic recording medium 42 Magnetic recording medium drive unit 43 Magnetic head 44 Magnetic head drive unit 45 Recording/playback signal processing system

Claims (5)

[Claims] 1. A hard nonmagnetic substrate, an underlayer made of a nonmagnetic nickel-based alloy with a face-centered cubic structure provided on the substrate, and a cobalt-based alloy magnetic layer provided on the underlayer. A magnetic recording medium characterized by comprising: 2. The thickness of the base layer is between 20 and 90 mm.
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a diameter of nm. 3. The underlayer is an underlayer made of a non-magnetic nickel-based alloy having a (100) plane of a face-centered cubic structure on the surface of the underlayer parallel to the recording surface, and the cobalt-based alloy magnetic layer is 3. The magnetic recording medium according to claim 1, wherein the underlayer is epitaxially grown on the (100) plane so that the (110) plane of the hexagonal close-packed structure is parallel to the recording surface. 4. 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. 5. A magnetic storage device comprising a magnetic recording medium, a drive section for rotationally driving the magnetic recording medium, a magnetic head and its driving means, and a recording/reproduction signal processing means for the magnetic head, wherein the magnetic recording medium is A magnetic storage device characterized in that the magnetic recording medium according to claim 1 is used as a medium.