JP2007272990A - Magnetic recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote separation structure in a magnetic layer by increasing surface coarseness R<SB>a</SB>of an intermediate layer without thickening a film thickness, as regards a magnetic recording medium and its manufacturing method. <P>SOLUTION: At least the surface part of the intermediate layer 3 of the magnetic recording medium in which the intermediate layer 3 for controlling crystal orientation of a recording layer 8 and for uniformly isolating magnetic particles 6 is provided between a soft magnetic backing layer 2 and the recording layer 8 provided on a substrate 1 is made granular structure of metal particles comprised of Ru or RU alloy and a non-magnetic base material 7, and the metal particles 6 comprised of Ru or Ry alloy are projected from the non-magnetic base material 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium and a method for manufacturing the same, and more particularly to a configuration for improving signal quality in a magnetic recording medium necessary for increasing the recording density of a magnetic disk apparatus using a perpendicular magnetic recording system. The present invention relates to a magnetic recording medium having the same and a manufacturing method thereof.

In recent years, high-density recording is strongly demanded in HDD magnetic recording media as the data size handled increases.
As a response to such a demand for high density recording, a perpendicular recording method using a recording layer having an easy axis direction in the direction perpendicular to the substrate has been proposed.

As such a perpendicular magnetic recording medium, a so-called granular structure in which magnetic alloy particles containing Co, Cr, Pt or the like are separated by a nonmagnetic base material such as SiO ₂ is widely used.

The perpendicular recording medium in order to improve recording and reproducing characteristics to have a separated structure is known to be desirable surface roughness R _a of the Ru intermediate layer is large. (For example, refer nonpatent literature 1).

Here, a conventional magnetic recording medium will be described with reference to FIG.
See Figure 5
FIG. 5 is a conceptual cross-sectional view of a conventional magnetic recording medium. First, on a crystallized glass substrate 31, a seed layer 32, a soft magnetic backing layer 33, a Ru intermediate layer 34, a magnetic recording layer 35 having a granular structure, and After the protective layers 36 are sequentially deposited, a lubricant 37 is applied to the surface.

  In such a perpendicular recording medium, it is necessary to increase the surface roughness of the Ru intermediate layer 34 in order to obtain predetermined recording / reproducing characteristics. For this purpose, it is necessary to increase the Ru film thickness to about 20 nm or more. is there.

On the other hand, in order to promote the separation structure in the magnetic recording layer 35, it has been proposed that the intermediate layer is composed of a lower intermediate layer made of Ru and an upper intermediate layer having a granular structure made of Ru particles and Si oxide. (For example, refer to Patent Document 1 or Patent Document 2).
49th Annual Conference on Magnetics & Magnetic Materials DB-11 “Effect of Ru Intermediate Layer on Properties of CoCrPt-SiO2 Perpendicular Recorder” JP 2005-093040 A JP 2005-108268 A

However, if the thickness of the Ru intermediate layer is increased in order to increase the surface roughness _Ra , the distance between the recording head and the soft magnetic underlayer increases, the recording characteristics deteriorate, and the magnetic field gradient during recording also decreases. However, there is a problem that the transition area between recording bits becomes unclear, which causes an increase in the medium noise N _m and the signal quality decreases.

In order to improve the recording characteristics of the perpendicular recording medium, clear the transition region between recording bits, and reduce the medium noise N _m , the Ru intermediate layer may be thinned. There is a problem that the recording / reproducing characteristics are deteriorated due to _a decrease in _Ra .

  Even when the upper part of the intermediate layer has a granular structure, isolation of the magnetic particles in the recording layer is not always sufficient, and there is no particular problem regarding the film thickness of the intermediate layer. When the seed layer provided between the layers is included, the distance between the soft magnetic backing layer and the recording layer is 21 nm or more, and as a result, there is a problem that the distance between the recording head and the soft magnetic backing layer increases.

Accordingly, the present invention is, without increasing the film thickness of the intermediate layer, and an object thereof is the surface roughness R _a of the intermediate layer is increased to promote separation structure in the magnetic layer.

FIG. 1 is a diagram illustrating the basic configuration of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
See FIG. 1 In order to solve the above-mentioned problem, the present invention is for controlling the crystal orientation of the recording layer 8 and isolating the magnetic particles uniformly between the soft magnetic backing layer 2 and the recording layer 8 provided on the substrate 1. The intermediate layer 3 is provided with a magnetic recording medium in which at least a surface portion has a granular structure of a metal particle 6 made of Ru or a Ru alloy and a non-magnetic base material 7, and the Ru or Ru alloy. The metal particle 6 made of is protruded from the nonmagnetic base material 7.

In this way, at least the surface portion of the intermediate layer 3 is composed of the granular structure of the metal particles 6 made of Ru or Ru alloy and the nonmagnetic base material 7, and the metal particles 6 made of Ru or Ru alloy are made of the nonmagnetic base material 7. by configuring so as to protrude from, it is possible to increase the surface roughness R _a of the intermediate layer 3 without increasing the thickness of the intermediate layer 3, thereby to promote isolation structure in the magnetic layer it can.

In this case, in order to sufficiently increase the surface roughness R _a of the intermediate layer 3, the top of the metal particles 6 made of Ru or Ru alloy, as an average from the surface of the non-magnetic matrix 7 to embed the metal particles 6 It is desirable to project 1 nm or more.

The nonmagnetic base material 7 may be any nonmagnetic material having selective etching properties with respect to Ru or Ru alloy. For example, it may be a nonmagnetic metal such as Cu, but selected with respect to Ru or Ru alloy. SiO ₂ or SiN that is easy to dry-etch is desirable.

  The intermediate layer 3 may be composed of a single intermediate layer 3 having a granular structure, but the lower intermediate layer 4 made of Ru or Ru alloy and the lower part of the granular structure of Ru or Ru alloy and the nonmagnetic base material 7. The intermediate layer 5 may be used, whereby the crystal orientation in the recording layer 8 and uniform isolation of the magnetic particles can be satisfactorily performed.

In this case, the thickness of the lower intermediate layer 4 is preferably 10 nm or less, whereby the distance between the recording head and the soft magnetic backing layer 2 is reduced, and the recording characteristics are improved. Since the magnetic field gradient is lowered and the transition region between recorded bits becomes clear, the medium noise N _m can be reduced.
The distance between the soft magnetic backing layer 2 and the recording layer 8 is preferably 20 nm or less.

  In this case, the recording layer 8 is typically a granular structure of magnetic particles and a nonmagnetic base material.

  In the case of manufacturing the above-described configuration, an intermediate layer having a granular structure of metal particles 6 and a nonmagnetic base material 7 having at least a surface portion made of Ru or Ru alloy on a substrate 1 with a soft magnetic backing layer 2 interposed therebetween. 3, the surface portion of the nonmagnetic base material 7 constituting the intermediate layer 3 may be selectively etched away with respect to the metal particles 6.

In particular, when the nonmagnetic base material 7 constituting the intermediate layer 3 is made of either SiO ₂ or SiN, the nonmagnetic base material 7 can be easily selectively removed by dry etching.

  By mounting the magnetic recording medium having the above-described configuration, high-density recording of the magnetic disk device is realized.

According to the present invention, it is possible to increase the surface roughness R _a of the intermediate layer without increasing the thickness of the intermediate layer whose main component a Ru, whereby uniform magnetic particles in the magnetic recording layer Signal quality is improved.

The present invention has a thickness of, for example, a lower intermediate layer made of a Ru alloy such as Ru or RuCr with a thickness of 10 nm or less on a substrate such as a crystallized glass substrate via a soft magnetic backing layer such as CoZrNb. After providing an intermediate layer having a laminated structure of a metal particle made of a Ru alloy such as Ru or RuCr of 10 nm or less and a non-magnetic base material, particularly an upper intermediate layer made of a SiO ₂ or SiN granular structure, the intermediate layer The surface portion of the nonmagnetic base material constituting the material is selectively etched with respect to the metal particles, preferably by dry etching, and thereafter, the recording layer having a granular structure such as CoCrPt—SiO _{2 and} the protection of CN, etc. A layer and a lubricant are sequentially provided.

Here, with reference to FIG. 2 thru | or FIG. 3, the manufacturing process of the magnetic-recording medium of Example 1 of this invention is demonstrated.
In the figure, the structure is shown as being deposited on one side of the substrate, but in actuality, it is deposited on both sides of the substrate simultaneously.
See Figure 2
First, a seed layer 12 made of TiW having a thickness of, for example, 10 nm, a soft magnetic backing layer 13 made of, for example, 50 nm of CoZrNb, and having a thickness of 10 nm on the crystallized glass substrate 11 by sputtering. Hereinafter, for example, a lower intermediate layer 14 made of Ru of 5 nm and an upper intermediate layer 15 made of Ru-SiO ₂ granular structure having a thickness of 10 nm or less, eg 5 nm are sequentially deposited.
In this case, the upper intermediate layer 15 has a Ru—SiO ₂ granular structure in which, for example, 10 mol% of SiO ₂ is added to Ru, and Ru particles 16 are embedded in the SiO ₂ base material 17.

Next, the SiO ₂ base material 17 constituting the upper intermediate layer 15 is formed using plasma generated by applying Ar as an etching gas, for example, 15 sccm, CF _4, for example, 25 sccm, applying a source power of 300 W, and a bias power of 30 W. the exposed portion is selectively etched by projecting the Ru particles 16 to increase the surface roughness R _a in.

In this case, the etching amount is such that each top portion of the Ru particles 16 protrudes from the surface of the SiO ₂ base material 17 embedding the Ru particles 16 on the average by 1 nm or more, more preferably 2 nm or more.

See Figure 3
Next, a recording layer 18 having a CoCrPt—SiO ₂ granular structure in which CoCrPt particles are embedded in a SiO ₂ base material having a thickness of, for example, 50 nm is deposited again using the sputtering method.
At this time, CoCrPt particles constituting the recording layer 18 with crystal orientation of Ru particles 16 constituting the upper intermediate layer 15 is controlled, is uniformly isolated by surface roughness R _a of Ru particles 16.

  Thereafter, a protective layer 19 made of CN (carbon nitride) having a thickness of, for example, 3 nm is formed by sputtering, and then a perfluorocarbon-based lubricant 20 is applied, for example. The basic configuration of the magnetic recording medium is completed.

In the first embodiment of the present invention, the intermediate layer has a laminated structure of an upper intermediate layer 15 / lower intermediate layer 14, the upper intermediate layer 15 has a Ru-SiO ₂ granular structure, and the exposed surface of the SiO ₂ base material is formed. since selectively etched, without increasing the thickness of the entire intermediate layer, it is possible to increase the surface roughness R _a of the upper intermediate layer 15.

Next, the manufacturing process of the magnetic recording medium according to the second embodiment of the present invention will be described with reference to FIG. 4. Since the basic manufacturing process is the same as that of the first embodiment, the final structure is illustrated.
See Figure 4
First, a seed layer 22 made of TiW having a thickness of 10 nm, for example, a soft magnetic backing layer 23 made of CoZrNb having a thickness of 50 nm, for example, on the crystallized glass substrate 21, and a thickness thereof. The intermediate layer 24 having a Ru—SiO ₂ granular structure with a thickness of 10 nm or less, for example, 5 nm is sequentially deposited.
In this case, the intermediate layer 24 has a Ru—SiO ₂ granular structure in which, for example, 10 mol% of SiO ₂ is added to Ru, and Ru particles 25 are embedded in the SiO ₂ base material 26.

Next, exposure of the SiO ₂ base material 26 constituting the intermediate layer 24 using plasma generated by applying Ar as an etching gas, for example, 15 sccm, CF _4, for example, 25 sccm, applying a source power of 300 W, and a bias power of 30 W. part selectively etched by projecting the Ru particles 25 to increase the surface roughness R _a in.

The etching amount in this case is such that each top portion of the Ru particles 25 protrudes from the surface of the SiO ₂ base material 26 embedding the Ru particles 25 on average at least 1 nm, more preferably at least 2 nm.

Next, the recording layer 27 having a CoCrPt—SiO ₂ granular structure in which CoCrPt particles are embedded in a SiO ₂ base material having a thickness of, for example, 10 nm is deposited again by using the sputtering method.
At this time, CoCrPt particles constituting the recording layer 27 with crystal orientation of Ru particles 25 constituting the intermediate layer 24 is controlled, is uniformly isolated by surface roughness R _a of Ru particles 25.

  Thereafter, after forming a protective layer 28 made of CN (carbon nitride) having a thickness of, for example, 3 nm by sputtering, for example, by applying a perfluorocarbon-based lubricant 29, Example 2 of the present invention is applied. The basic configuration of the magnetic recording medium is completed.

In the second embodiment of the present invention, since the intermediate layer is composed of a single layer of Ru—SiO ₂ granular structure, the distance between the soft magnetic backing layer and the recording head can be further shortened. The recording characteristics are improved, and further, the magnetic field gradient during recording is increased, and the transition region between recording bits becomes clear.
However, since the Ru lower intermediate layer is not provided, the crystal orientation controllability of the magnetic particles constituting the recording layer is slightly lowered.

  The embodiments of the present invention have been described above, but the present invention is not limited to the configurations and conditions described in the embodiments, and various modifications are possible. For example, in the above-described first embodiment The metal particles of the lower intermediate layer and the upper intermediate layer are made of Ru, but are not limited to Ru, and a Ru alloy such as RuCr may be used.

In each of the above embodiments, SiO ₂ is used as the nonmagnetic base material constituting the upper intermediate layer or the intermediate twin, but is not limited to SiO _2, and good selective etching for Ru or Ru alloy. For example, a non-insulating film such as SiN or SiON may be used.

  Furthermore, a nonmagnetic metal such as Cu may be used as the nonmagnetic base material. In this case, selective dry etching is difficult, and wet etching using sulfuric acid may be performed.

In each of the above embodiments, the intermediate layer is directly provided on the soft magnetic backing layer, but may be provided via a seed layer such as Ta, NiFe, NiFeCr or the like.
However, in this case, the seed layer may be about 3 nm thick and the distance between the soft magnetic backing layer and the recording layer may be 20 nm or less.

  In each of the above embodiments, a crystallized glass substrate is used as the substrate, but it is not limited to a crystallized glass substrate, and various materials excellent in surface smoothness and mechanical strength are used. It may be used as a substrate.

In each of the above embodiments, CoZrNb is used as the soft magnetic layer, but is not limited to CoZrNb, and CoZrTa, FeCoB, FeTaC, FeTaN, FeAlSi, FeCoAlO, and CoNiFeB that are excellent in high-frequency response like CoZrNb. Other soft magnetic materials such as CoFe ₂ O ₄ , ZnFe ₂ O ₄ , and CoFe may be used.

Further, in the embodiments described above uses a CoCrPt-SiO ₂ having a perpendicular magnetic anisotropy as a recording layer, but not limited to _{CoCrPt-SiO 2, CoCrPt-Ta} 2 O 5, CoCrPt-TiO ₂ , CoCrPtO, (Pt / Co) _n , (Fe / Pt) _n, or the like may be used.
When a superlattice structure such as (Pt / Co) _n or (Fe / Pt) _n is used, a non-magnetic material such as SiO ₂ is sputtered simultaneously with the formation of each layer such as Pt, Co, or Fe. Just do it.

  In each of the above embodiments, CN is used as the protective layer, but is not limited to CN, and DLC (diamond-like carbon), SiN, or the like may be used.

  In each of the above embodiments, the soft magnetic backing layer, the intermediate layer, and the recording layer are formed using the sputtering method, but the present invention is not limited to the sputtering method. Is also good.

Here, the detailed features of the present invention will be described again with reference to FIG.
Again see Figure 1
(Supplementary Note 1) A magnetic recording medium in which an intermediate layer 3 for controlling the crystal orientation of the recording layer 8 and isolating magnetic particles uniformly is provided between the soft magnetic backing layer 2 and the recording layer 8 provided on the substrate 1. At least the surface portion of the intermediate layer 3 has a granular structure of a metal particle 6 made of Ru or Ru alloy and a nonmagnetic base material 7, and the metal particle 6 made of Ru or Ru alloy has a nonmagnetic base. A magnetic recording medium which protrudes from the material 7.
(Additional remark 2) Each top part of the metal particle 6 which consists of said Ru or Ru alloy protrudes 1 nm or more from the surface of the nonmagnetic base material 7 which embeds the said metal particle 6 as an average value, The additional description 1 characterized by the above-mentioned Magnetic recording medium.
(Supplementary Note 3) The magnetic recording medium according to appendix 1 or 2 the non-magnetic matrix 7, characterized in that it consists of one of SiO ₂ or SiN.
(Additional remark 4) The said intermediate | middle layer 3 consists of the lower intermediate | middle layer 5 which consists of Ru or Ru alloy, and the upper intermediate | middle layer 4 of the granular structure of the said Ru or Ru alloy and the nonmagnetic base material 7 characterized by the above-mentioned. The magnetic recording medium according to any one of 1 to 3.
(Additional remark 5) The thickness of the said lower intermediate | middle layer 5 is 10 nm or less, The magnetic recording medium of Additional remark 4 characterized by the above-mentioned.
(Supplementary note 6) The magnetic recording medium according to any one of supplementary notes 1 to 5, wherein an interval between the soft magnetic backing layer 2 and the recording layer 8 is 20 nm or less.
(Supplementary note 7) The magnetic recording medium according to any one of supplementary notes 1 to 6, wherein the recording layer 8 comprises a granular structure of magnetic particles 6 and a nonmagnetic matrix.
(Additional remark 8) After providing the intermediate layer 3 which consists of the granular structure of the metal particle 6 and the nonmagnetic base material 7 which at least surface part consists of Ru or Ru alloy on the board | substrate 1 via the soft-magnetic backing layer 2, the said intermediate | middle A method of manufacturing a magnetic recording medium, comprising a step of selectively removing the surface portion of the nonmagnetic base material 7 constituting the layer 3 by etching with respect to the metal particles 6.
(Supplementary Note 9) non-magnetic matrix 7 constituting the intermediate layer 3 is, note 8 consist either of SiO ₂ or SiN, characterized in that said non-magnetic matrix 7 is selectively removed by dry etching A method for producing the magnetic recording medium according to claim.
(Additional remark 10) A magnetic disk device comprising the magnetic recording medium according to any one of additional remarks 1 to 7.

It is explanatory drawing of the fundamental structure of this invention. It is explanatory drawing of the manufacturing process to the middle of the magnetic recording medium of Example 1 of this invention. It is explanatory drawing of the manufacturing process after FIG. 2 of the magnetic recording medium of Example 1 of this invention. It is a conceptual sectional view of the magnetic recording medium of Example 2 of the present invention. It is a conceptual sectional view of a conventional magnetic recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Soft magnetic backing layer 3 Intermediate layer 4 Lower intermediate layer 5 Upper intermediate layer 6 Metal particle 7 Nonmagnetic base material 8 Recording layer 11 Crystallized glass substrate 12 Seed layer 13 Soft magnetic backing layer 14 Lower intermediate layer 15 Upper intermediate layer 16 Ru particles 17 SiO ₂ base material 18 Recording layer 19 Protective layer 20 Lubricant 21 Crystallized glass substrate 22 Seed layer 23 Soft magnetic backing layer 24 Intermediate layer 25 Ru particles 26 SiO ₂ base material 27 Recording layer 28 Protective layer 29 Lubricant 31 Crystallized glass substrate 32 Seed layer 33 Soft magnetic backing layer 34 Ru intermediate layer 35 Magnetic recording layer 36 Protective layer 37 Lubricant

Claims (5)

A magnetic recording medium comprising an intermediate layer for controlling the crystal orientation of the recording layer and isolating magnetic particles uniformly between a soft magnetic underlayer and a recording layer provided on a substrate, wherein at least the surface of the intermediate layer The magnetic recording medium is characterized in that the portion has a granular structure of a metal particle made of Ru or Ru alloy and a nonmagnetic matrix, and the metal particle made of Ru or Ru alloy protrudes from the nonmagnetic matrix. . 2. The magnetic recording medium according to claim 1, wherein each top of the metal particles made of Ru or Ru alloy protrudes from the surface of the nonmagnetic base material in which the metal particles are embedded by an average value of 1 nm or more. The magnetic recording medium according to claim 1, wherein the nonmagnetic base material is made of either SiO ₂ or SiN. 4. The intermediate layer according to claim 1, wherein the intermediate layer includes a lower intermediate layer made of Ru or Ru alloy, and an upper intermediate layer having a granular structure of the Ru or Ru alloy and a nonmagnetic base material. The magnetic recording medium according to Item. An intermediate layer comprising a granular structure of metal particles and a non-magnetic base material, at least the surface portion of which is made of Ru or Ru alloy, is provided on a substrate via a soft magnetic backing layer, and then the non-magnetic base material constituting the intermediate layer is provided. A method of manufacturing a magnetic recording medium comprising a step of selectively removing a surface portion of the metal particles by etching.

Images