JP2002092864A - Magnetic recording medium and magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium and a magnetic recording apparatus by growing sufficiently fine magnetic crystal grains with good reproducibility and achieving a high S / N ratio.
Increase ratio. SOLUTION: An island-like seed layer 3 made of either a Co layer or a Co alloy layer is provided on a non-magnetic substrate 1 made of an Al-based alloy substrate or a glass substrate via an amorphous film 2.
Is provided.

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 recording apparatus, and more particularly to a seed layer for forming fine crystal grains to obtain high output with low noise. The present invention relates to a magnetic recording medium and a magnetic recording device having features.

[0002]

2. Description of the Related Art In recent years, the recording density of a magnetic recording device such as a hard disk device has increased remarkably, and therefore, the interval between recording bits has become narrower as the recording density has increased. In order to form smaller recording bits on a magnetic recording medium, when the recording density is increased, the reproduction output is reduced, noise is increased, and the S / N ratio is reduced, as well as the performance of the recording head. Therefore, it is important to increase the S / N by reducing the noise of the magnetic recording medium.

Therefore, in a conventional magnetic recording medium,
Various attempts have been made to increase the S / N ratio. For example, many attempts have been made to control the crystal orientation of the underlayer, to improve the crystal orientation of the magnetic layer, to perform lattice matching, or to employ an intermediate layer. Method.

When an aluminum substrate is used, amorphous NiP is usually provided by controlling the composition ratio of a base layer in order to enhance the crystal orientation of Cr or a Cr alloy provided thereabove. I have. This is because a non-oriented film, that is, an amorphous film is required to increase the in-plane orientation of a Co alloy such as CoCrPtTa forming the magnetic layer.

That is, CoCrPtTa constituting the magnetic layer
When a Cr-based alloy is used as the intermediate layer in order to enhance the in-plane orientation of a Co alloy such as that described above, a Cr-based alloy having a bcc (body-centered cubic) structure needs to be oriented to Cr (200). For this reason, it was a major premise that the underlying layer such as the NiP layer immediately below the Cr-based alloy layer was amorphous.

This is because the surface of the Cr-based alloy layer has a (200)
When oriented so as to be a plane, 2 ^1/2 times the lattice spacing in the (200) plane is a hexagonal dense structure (hcp) of Co.
This is because the lattice spacing in the c-axis direction of the magnetic layer of CrPtTa or the like substantially matches, and as a result, the c-axis becomes horizontal (1
10) The magnetic layer is grown so that the plane becomes the main plane, and the magnetic layer is oriented in the plane.

[0007]

However, the conventional method for improving the output and reducing the noise by increasing the orientation of the magnetic layer has not been able to sufficiently improve the S / N ratio.

On the other hand, in order to obtain a high S / N ratio, crystal grains of the magnetic layer have been made small, but the magnetic layer has
Since the epitaxial growth is performed while reflecting the crystal state of the intermediate layer made of the r-based alloy, it is difficult to sufficiently reduce the crystal grains of the magnetic layer by the above-described method of increasing the orientation, and it is not always necessary to obtain a sufficiently high S / N ratio. Could not get.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to increase the S / N ratio by making magnetic crystal grains sufficiently fine and uniform, growing with good reproducibility.

[0010]

FIG. 1 is an explanatory view of the principle configuration of the present invention. Referring to FIG. 1, means for solving the problems in the present invention will be described. See FIG. 1. In order to solve the above-mentioned problem, in the present invention, Al
A seed layer 3 made of either a Co layer or a Co alloy layer on a non-magnetic substrate 1 made of a system alloy substrate or a glass substrate with an amorphous film 2 interposed therebetween, in particular, one of a Co layer or a Co alloy layer of an island film And a seed layer 3 comprising: In this case, it is desirable that the thickness of the seed layer 3 made of either a Co layer or a Co alloy layer be 2 nm or less in terms of a continuous film.

As described above, by providing the island-shaped seed layer 3 made of either a Co layer or a Co alloy layer,
Since crystal growth is performed using the island-shaped seed layer 3 as a nucleus, crystal grains of the magnetic layer 5 can be made finer according to the distribution density of the island-shaped seed layer 3, thereby reducing noise. At the same time, the output can be increased to increase the S / N ratio.

In this case, the thickness of the seed layer 3 made of either a Co layer or a Co alloy layer is set to 2 nm in terms of a continuous film.
By doing so, the magnetostatic characteristics of the seed layer 3 do not affect the magnetostatic characteristics of the magnetic layer 5, and
Since the seed layer 3 does not affect the orientation of the magnetic layer 5, the orientation of the magnetic layer 5 can also be kept good.

Further, by configuring a magnetic recording apparatus using such a magnetic recording medium, the recording density can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a magnetic recording medium according to a first embodiment of the present invention will be conceptually described with reference to FIG. Each drawing is a schematic configuration diagram of the magnetic recording medium according to the first embodiment of the present invention, and has a structure in which recording layers are provided symmetrically on both sides of the substrate. Referring to FIG. 2A, first, for example, 3.5 inches (≒ 8.9 cm) of Al ₉₅
An amorphous NiP reinforcing layer 12 made of Ni ₈₁ P ₁₉ having a thickness of, for example, 10 μm is provided on an Al—Mg alloy substrate 11 made of Mg ₅ (weight ratio) by plating. To increase the mechanical strength of the magnetic head to ensure contact reliability with the magnetic head during high-speed rotation.

Next, if necessary, texture processing using abrasive grains is performed to form fine grooves along the circumferential direction of the surface of the NiP reinforcing layer 12, or irregularities are formed by performing irregularities processing. Form. The grooves formed by the texture processing or the concavities and convexities formed by the concavo-convex processing reduce the friction between the magnetic head and the magnetic disk recording medium to prevent the magnetic head from being attracted. , The magnetic anisotropy in the in-plane recording direction can be increased.

Next, referring to FIG. 2 (b), using a single-wafer type DC-magnetron sputtering apparatus in which a plurality of chambers are partitioned by gate valves, Co is continuously supplied at a degree of vacuum of, for example, 5 × 10 ⁻⁶ Pa. The island-shaped Co seed layer 13 is formed by sputtering a film equivalent to 2 nm or less. In this case, as in the case of ordinary metal film deposition, when the film thickness is extremely small, fine crystal growth nuclei are dispersed and generated on the NiP reinforcing layer 12, and crystal growth is performed using the fine crystal growth nuclei as nuclei. However, when the film thickness is 2 nm or less, island-like films separated from each other are formed. In addition, the continuous film equivalent film thickness of 1 nm is a sputtering amount that can obtain a 1 nm layer when it is assumed that the film is formed as a continuous film.
Here, 0.5 nm, 1 nm, 1.25 nm, 2 nm
The four types of film thickness were deposited.

Subsequently, as shown in FIG. 2 (c), after being carried into the adjacent chamber via a gate valve, the thickness of the Cr ₉₀ layer is, for example, 10 nm.
The CrMo underlayer 14 made of Mo ₁₀ is deposited. In this case, since the CrMo underlayer 14 is epitaxially grown using the island-shaped Co seed layer 13 as a growth nucleus, a columnar polycrystal having a size corresponding to the distribution density of the island-shaped Co seed layer 13 is obtained.

Subsequently, as shown in FIG. 2D, after the wafer is carried into the adjacent chamber through a gate valve, the thickness of the Co ₆₉ is, for example, 20 nm.
CoCrPtTa magnetic layer 1 made of Cr ₂₁ Pt ₈ Ta ₂
5 is epitaxially grown on the CrMo underlayer 14,
Next, after being carried into an adjacent chamber via a gate valve, a DLC (diamond-like carbon) film 16 having a thickness of, for example, 8 nm is deposited. Thereafter, although not shown, a basic configuration of the magnetic recording medium is completed by applying a fluorine-based lubricant on the DLC film 16 and drying it.

Various measurements were made on the magnetic recording medium manufactured as described above. The measurement results will be described with reference to FIGS. In the case of the measured magnetic recording medium, the above-described texture processing was not performed.

FIG. 3A is a graph showing the dependency of S / N _{m on} the Co layer thickness. As the thickness of the island-shaped Co seed layer increases, S / N _m also increases. S / N _m from 1.25 nm to 2 nm
Rapidly worsens. Incidentally, the N _m is the medium noise (N _media).

[0021] see FIG. 3 (b) Figure 3 (b) is a diagram showing a Co layer thickness dependence of the noise N _m and the output S individually output with the thickness increase of the island Co seed layer To increase. On the other hand, although the noise decreases as the thickness of the island-shaped Co seed layer increases, the noise rapidly deteriorates from 1.25 nm to 2 nm.

This is because the island-shaped Co seed layer becomes thicker,
This is considered to be because the magnetostatic characteristics of Co began to affect the magnetostatic characteristics of the magnetic layer.
It is considered that this has affected the rapid deterioration of S / N _m shown in FIG. The noise in the figure is represented by the root mean square, and the output is represented as a value between peaks between the upper peak and the lower peak of the sine wave output waveform.

FIG. 4 is a diagram showing the dependency of the MH loop characteristic on the Co layer thickness. When the thickness of the island-shaped Co seed layer is 2 nm, the magnetic characteristics of the island-shaped Co seed layer are shown. Becomes a loop reflecting
In other cases, it is understood that the MH loop characteristics are almost the same as those in the case where the island-shaped Co seed layer is not provided.

FIG. 5 is a graph in which intensity profiles at each incident angle θ in XRD measurement are arranged and compared for each layer thickness of the island-shaped Co seed layer. As is apparent from the figure, Co-hcp showing the in-plane orientation of the CoCrPtTa film as the magnetic layer.
It is understood that the peak of (110) hardly changes with the thickness of the island-shaped Co seed layer. It should be noted that all the steep large peaks in the profile are peaks due to Al.

Judging comprehensively from the above, the orientation of the magnetic layer is hardly affected by the provision of the island-shaped Co seed layer, and a high S / N _m can be obtained. d)
From the fact that the crystal grains are fine as conceptually shown in FIG. 3, the noise rapidly increases in FIG. 3B, and the MH loop characteristic shown in FIG. 4, the island-shaped Co seed layer has a thickness of 2 nm. When the thickness exceeds 1, the influence of the magnetic properties of the island-shaped Co seed layer increases, and the magnetic properties of the entire magnetic recording medium deteriorate. Therefore, the layer thickness of the island-shaped Co seed layer needs to be 2 nm or less in terms of continuous film thickness. It is understood that there is.

Next, a second embodiment of the present invention using a glass substrate will be described with reference to FIG. 6, but the basic manufacturing steps are exactly the same as those of the first embodiment. So
The description of the specific manufacturing method is omitted. FIG. 6 is a schematic configuration diagram of a magnetic recording medium according to the second embodiment of the present invention, which has a structure in which recording layers are provided symmetrically on both sides of a substrate. First, for example, 2.5
On a glass substrate 21 of inch (μ6.35 cm), for example, a 0.05 μm thick Cr
An amorphous NiP reinforcing layer 23 made of Ni ₈₁ P ₁₉ is sequentially deposited via the adhesion layer 22.

Thereafter, similarly to the first embodiment, the island-like Co seed layer 24,
After sequentially depositing a CrMo underlayer 25, a CoCrPtTa magnetic layer 26, and a DLC film 27, a DLC film 27 is formed.
The basic structure of the magnetic recording medium is completed by applying a fluorine-based lubricant 28 thereon and drying the lubricant.

In the second embodiment, the basic characteristics are the same as those of the first embodiment except for the structure of the substrate, and a small magnetic recording device having a diameter of 2.5 inches or less is used. Useful for media.

Next, a modification of the magnetic recording medium according to the second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic configuration diagram of a magnetic recording medium according to a third embodiment of the present invention. In practice, the magnetic recording medium has a structure in which recording layers are provided symmetrically on both sides of a substrate. As is clear from the figure, the island-shaped Co seed layer 24 is provided directly on the glass substrate 21, and the other configuration is the same as that of the above-described second embodiment.

In this case, since the glass substrate 21 itself is amorphous, NiP which provides an amorphous film is used.
It does not require the reinforcing layer 22. by this,
Although two manufacturing steps can be omitted, the strength of the substrate slightly decreases, and the island-like Co seed layer 24 and the Cr
The adhesion between the Mo underlayer 25 and the glass substrate 21 is slightly reduced.

The embodiments of the present invention and the modifications thereof have been described above. However, the present invention is not limited to the configurations and conditions described in the above embodiments and the modifications thereof, but may be applied to various embodiments. Changes are possible. For example, if the seed layer is C
Although it is formed by o, it is not limited to Co, and a Co-based alloy such as Co ₉₀ Pt ₁₀ or Co ₇₀ Cr ₃₀ may be used.

Further, in each of the above embodiments, the Al-Mg alloy is used as the substrate. However, the present invention is not limited to the Al-Mg alloy, and other Al-based materials such as Al-Cu, Al-Si, etc. An alloy may be used.

In each of the above embodiments, Cr ₉₀ Mo ₁₀ is used as the underlayer.
rMo may be used, and furthermore, Cr, CrRu, or
CrW may be used.

In each of the above embodiments, the magnetic
Co as the active layer₆₉Cr_{twenty one}Pt₈Ta_TwoUsing
However, a CoCrPtTa alloy having another composition ratio may be used.
Co ₇₄Cr_FifteenPt_FourTa_FourNb_ThreeCoCrPt
TaNb alloy or Co_76.3Cr₁₇Pt_6.7Etc. C
oCrPt alloy may be used.
Co alone may be used, and in any case, Co or Co
A Co alloy containing at least Pt and containing at least Pt
No. This is because the Co alloy has a hexagonal close-packed structure and
The o-Pt alloy has uniaxial anisotropy and has a moderately high coercive force.
This is because they can be obtained.

Here, the detailed features of the present invention will be described with reference to FIG. 1 again. FIG. 1 (Supplementary Note 1) A magnetic recording medium characterized in that a seed layer 3 made of either a Co layer or a Co alloy layer is provided on an Al-based alloy substrate via an amorphous film 2. (Supplementary note 2) The magnetic recording medium according to supplementary note 1, wherein the Al-based alloy is an Al-Mg alloy. (Supplementary Note 3) A magnetic recording medium characterized in that a seed layer 3 made of either a Co layer or a Co alloy layer is provided directly on a glass substrate or via an amorphous film 2. (Supplementary Note 4) The magnetic recording medium according to any one of Supplementary Notes 1 to 3, wherein the seed layer 3 made of either the Co layer or the Co alloy layer is an island film. (Supplementary Note 5) The magnetic recording medium according to Supplementary Note 4, wherein the thickness of the seed layer 3 made of either the Co layer or the Co alloy layer is 2 nm or less in terms of a continuous film. (Supplementary Note 6) The magnetic recording medium according to any one of Supplementary Notes 1 to 5, wherein a magnetic layer 5 is provided via a Cr-based alloy layer 4 on the seed layer 3 made of either the Co layer or the Co alloy layer. 3. The magnetic recording medium according to claim 1. (Supplementary Note 7) A magnetic recording apparatus using the magnetic recording medium according to any one of Supplementary Notes 1 to 6 as a magnetic recording medium.

[0036]

According to the present invention, the underlayer and the magnetic layer made of the Cr-based alloy are sequentially provided on the substrate via the island-like seed layer, so that the crystal grains of the magnetic layer are reduced to the island-like seed layer. , Which can reduce noise, increase output, and increase S / N. Therefore, it is possible to increase the capacity of a magnetic disk recording device such as a hard disk device and achieve high-density magnetic recording. The contribution is great.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process of the magnetic recording medium according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of dependency of a noise characteristic on a Co layer thickness.

FIG. 4 is an explanatory diagram of the dependency of the MH loop characteristic on the Co layer thickness.

FIG. 5 is an explanatory diagram of the dependency of the XRD spectrum on the Co layer thickness.

FIG. 6 is a schematic configuration diagram of a magnetic recording medium according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a modification of the magnetic recording medium according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic substrate 2 Amorphous film 3 Seed layer 4 Cr-based alloy layer 5 Magnetic layer 11 Al-Mg alloy substrate 12 NiP reinforcing layer 13 Island-shaped Co seed layer 14 CrMo underlayer 15 CoCrPtTa layer 16 DLC layer 21 Glass substrate 22 Cr adhesion Layer 23 NiP reinforcing layer 24 Island-shaped Co seed layer 25 CrMo underlayer 26 CoCrPtTa layer 27 DLC layer 28 Lubricant

Claims (5)

[Claims] 1. A magnetic recording medium comprising a seed layer made of either a Co layer or a Co alloy layer provided on an Al-based alloy substrate via an amorphous film. 2. A magnetic recording medium having a seed layer made of either a Co layer or a Co alloy layer provided directly on a glass substrate or via an amorphous film. 3. The magnetic recording medium according to claim 1, wherein the seed layer made of one of the Co layer and the Co alloy layer is an island film. 4. The magnetic recording medium according to claim 3, wherein the thickness of the seed layer made of either the Co layer or the Co alloy layer is 2 nm or less in terms of a continuous film. 5. A magnetic recording apparatus using the magnetic recording medium according to claim 1 as a magnetic recording medium.