JP2021106068A - Magnetic recording medium, method of manufacturing the same, and magnetic storage device - Google Patents

Abstract

To provide a magnetic recording medium capable of improving the (001)-orientation of a magnetic layer.SOLUTION: A magnetic recording medium 100 includes: a substrate 1; an underlayer 2; and a magnetic layer 30 in this order. The underlayer 2 includes a first underlayer 21 containing a compound represented by a general formula: MgO(1-X), where X is within a range of 0.07 to 0.25. The magnetic layer 3 includes a first magnetic layer 31 containing an alloy having a L10 structure, and the alloy having the L10 structure includes B. The first underlayer 21 is in contact with the first magnetic layer 31.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetic recording medium, a method for manufacturing a magnetic recording medium, and a magnetic storage device.

The heat-assisted recording method for recording magnetic information by irradiating the magnetic recording medium with near-field light or the like to locally heat the surface to reduce the coercive force of the magnetic recording medium is a 1Tbit / inch ² class. It is attracting attention as a next-generation recording method that can achieve surface recording density. When the heat-assisted recording method is used, magnetic information can be easily recorded on a magnetic recording medium having a coercive force at room temperature of several tens of kOe by the recording magnetic field of the magnetic head. Therefore, the crystal magnetic anisotropy constant (Ku) is 10 6 ^{J /} m ³ units high material (high Ku material) can be applied to the magnetic layer, remains as a result, maintaining the thermal stability, magnetic The magnetic particles constituting the layer can be made finer until the particle size becomes 6 nm or less.

The high Ku material, FePt alloys ^{(Ku~7 × 10 6 J / m} 3), has been known an alloy having an L1 ₀ structure, such as a CoPt alloy ^{(Ku~5 × 10 6 J / m} 3).

In order to improve the surface recording density of the heat-assisted magnetic recording medium, the crystal orientation of the magnetic layer is improved, the magnetic particles constituting the magnetic layer are made finer, and the exchange bonds between the magnetic particles are reduced to reduce heat. It is necessary to improve the electromagnetic conversion characteristics of the assisted magnetic recording medium.

For example, when a FePt alloy film is used as the magnetic layer, the FePt alloy film needs to be (001) oriented in order to improve the crystal orientation of the magnetic layer. Therefore, it is desirable to use the (100) oriented MgO layer as the base layer. Here, (100) plane of MgO, (001) of the FePt alloy having an L1 ₀ structure due to high surface lattice matching with, on the MgO layer by depositing FePt alloy film, an FePt alloy film (001) Can be oriented.

Patent Document 1, the general _formula: a _{{(Fe x Pt 100-x} ) (100-y) B y} (100-z) C z, 30 ≦ x ≦ by atomic ratio 80, 1 ≦ y ≦ 20 A sputtering target for forming a magnetic recording medium film, which is made of a sintered body having a composition represented by 3 ≦ z ≦ 65, is disclosed.

Japanese Unexamined Patent Publication No. 2014-41682

The demand for improving the surface recording density of the magnetic recording medium does not stop, and it is required to improve the electromagnetic conversion characteristics of the magnetic recording medium. For this purpose, it is necessary to improve the regularity of the magnetic film and improve the orientation of the magnetic layer.

Therefore, it is conceivable to use a FePtB alloy film as the magnetic layer.

However, when a FePtB alloy film is formed on the MgO layer, B in the FePtB alloy and oxygen in MgO are mutually diffused to generate boron oxide, and as a result, the (001) orientation of the FePtB alloy film is changed. descend.

One aspect of the present invention is to provide a magnetic recording medium capable of improving the (001) orientation of the magnetic layer.

(1) A substrate, a base layer, and a magnetic layer are provided in this order, and the base layer is of the general formula MgO _(1-X).
(In the formula, X is in the range of 0.07 to 0.25.)
Having a first base layer containing the compound represented by in the magnetic layer includes an alloy having an L1 ₀ structure, the alloy having the L1 ₀ structure having a first magnetic layer including B, The first base layer is a magnetic recording medium in contact with the first magnetic layer.
(2) The method for producing a magnetic recording medium according to (1), wherein a sputtering target containing MgO and a sputtering gas in which hydrogen is added in the range of 1% by volume to 20% by volume of an inert gas. A method for producing a magnetic recording medium, which comprises a step of forming a film of the first base layer using the above.
(3) The method for producing the magnetic recording medium according to (1), which uses a sputtering target containing MgO and discharges at a sputtering gas pressure of 1 Pa or more for 0.5 seconds or less, and then 0.5 Pa or less. A method for producing a magnetic recording medium, which comprises a step of forming a first base layer by discharging with the sputter gas pressure of.
(4) A magnetic storage device having the magnetic recording medium according to (1).

According to one aspect of the present invention, it is possible to provide a magnetic recording medium capable of improving the (001) orientation of the magnetic layer.

It is sectional drawing which shows an example of the layer structure of the magnetic recording medium of this embodiment. It is a tilting view which shows an example of the magnetic storage device of this embodiment. It is a schematic diagram which shows an example of the magnetic head of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, the featured parts may be enlarged and shown, and the dimensional ratios of the respective components may not be the same. ..

[Magnetic recording medium]
FIG. 1 shows an example of the layer structure of the magnetic recording medium of the present embodiment.

The magnetic recording medium 100 includes a substrate 1, an underlayer 2, a magnetic layer 3 containing an alloy having an L1 ₀ structure in this order.

Here, in the base layer 2, the second base layer 22 and the first base layer 21 are sequentially laminated, and in the magnetic layer 3, the first magnetic layer 31 and the second magnetic layer 33 are sequentially laminated. ing.

The number of layers of the base layer 2 and the magnetic layer 3 is not particularly limited, and may be 3 or more, respectively.

The first base layer 21 is the uppermost layer of the base layer 2 (the layer farthest from the substrate 1), and is of the general formula MgO _(1-X) ... (A).
(In the formula, X is in the range of 0.07 to 0.25.)
Includes compounds represented by.

The first magnetic layer 31 is the lowermost magnetic layer 3 (the layer closest to the substrate 1), comprising an alloy having an L1 ₀ structure, the alloy having an L1 ₀ structure including B (boron).

Since the first base layer 21 is in contact with the first magnetic layer 31, the mutual diffusion between oxygen in the first base layer 21 and B in the first magnetic layer 31 is reduced, and the magnetic layer is formed. The (001) orientation of 3 is improved. This is because the first base layer 21 is in a state of being deficient in oxygen with respect to the stoichiometry (stoichiometric composition) of MgO, so that oxygen is supplied to the first magnetic layer 31. There is suppressed, because the oxidation of B forming an alloy having an L1 ₀ structure contained in the first magnetic layer 31 is reduced.

In the compound represented by the general formula (A), the oxygen deficiency amount X is in the range of 0.07 to 0.25, but is preferably in the range of 0.10 to 0.20. If the oxygen deficiency amount X is less than 0.07, the first B constituting the alloy having an L1 ₀ structure in the magnetic layer 31 is generated by partially oxidized by boron oxide, boron oxide grain boundary Since it moves to the portion, the (001) orientation of the magnetic layer 3 is lowered. On the other hand, when the oxygen deficiency amount X is larger than 0.25, the lattice constant of the compound represented by the general formula (A) contained in the first base layer 21 becomes small, and L1 contained in the first magnetic layer 31 becomes small. _Since the c-axis selective orientation of the alloy having the 0 structure is hindered, the (001) orientation of the magnetic layer 3 is lowered.

The oxygen deficiency amount X can be obtained by known methods such as expansion and contraction of the lattice constant of MgO by X-ray diffraction, secondary ion mass spectrometry (SIMS), electron probe microanalysis (EPMA), and X-ray photoelectron spectroscopy (XPS). Can be measured by.

The first base layer 21 can be formed into a film by a sputtering method.

When the first base layer 21 is formed, the first is used by using a sputtering target containing MgO and a sputtering gas in which hydrogen is added to the inert gas in the range of 1% by volume to 20% by volume. It is preferable to form the base layer 21. As a result, MgO can be reduced to form a film containing oxygen-deficient magnesium oxide, that is, a compound represented by the general formula (A).

When forming the first base layer 21, a sputtering target containing MgO is used to discharge at a sputtering gas pressure of 1 Pa or more for 0.5 seconds or less, and then discharge at a sputtering gas pressure of 0.5 Pa or less. Is preferable.

Since MgO is insulating, the RF sputtering method is used when forming the first base layer 21, but it is 0 by discharging at a sputtering gas pressure of 1 Pa or more for 0.5 seconds or less. It is possible to stably discharge at a sputtering gas pressure of .5 Pa or less, and it is possible to form a film containing magnesium oxide having high crystallinity and lacking oxygen.

Further, by discharging at a sputtering gas pressure of 0.5 Pa or less, a film containing magnesium oxide lacking oxygen can be stably formed. The reason why a film containing magnesium oxide, which is deficient in oxygen, can be stably formed is as follows. Along with the discharge, the oxygen atom separated from Mg recombines with the oxygen atom to generate an oxygen molecule, but a part of the oxygen molecule is usually adsorbed on the chamber wall. Here, when the sputtering gas pressure is 0.5 Pa or less, the amount of oxygen molecules released from the chamber wall is small, so that magnesium oxide can be in a state of oxygen deficiency.

Alloy having an L1 ₀ structure constituting the first magnetic layer 31 has a Fe or Co, it is preferable to further include a Pt.

The content of B in the alloy having an L1 ₀ structure is preferably in the range of 2 mol% 20 mol%, and more preferably in a range of 2.5 mol% 10 mol%. When the content of B in the alloy having an L1 ₀ structure is 2 mol% or more, improved (001) orientation of the magnetic layer 3, is not more than 20 mol%, the magnetic constituting the first magnetic layer 31 The magnetization of the particles is improved, and as a result, the magnetic recording signal strength of the magnetic recording medium 100 is improved.

The first magnetic layer 31 may further contain a grain boundary segregation material and have a granular structure. As a result, the first magnetic layer 31 is easily (001) oriented, and the lattice consistency with the (100) oriented first base layer 21 is improved.

Examples of the grain boundary segregation material contained in the first magnetic layer 31 include nitrides such as VN, BN, SiN and TiN, carbides such as C and VC, and borides such as BN, and two or more kinds thereof. May be used together.

The material constituting the second base layer 22 is not particularly limited as long as the first magnetic layer 31 can be (001) oriented, but for example, the (100) oriented W; Cr, Examples thereof include Cr alloys having a BCC structure and alloys having a B2 structure.

Examples of the Cr alloy having a BCC structure include CrMn alloys, CrMo alloys, CrW alloys, CrV alloys, CrTi alloys, CrRu alloys and the like.

Examples of alloys having a B2 structure include RuAl alloys and NiAl alloys.

When the number of layers of the base layer 2 is 3 or more, the base layers other than the first base layer 21 are the same as those of the second base layer 22.

The second magnetic layer 32 preferably comprises an alloy having an L1 ₀ structure. As a result, the (001) orientation of the magnetic layer 3 is improved. That is, as the second magnetic layer 32, a magnetic film epitaxially grown along the orientation of the first magnetic layer 31 can be formed.

Alloy having an L1 ₀ structure contained in the second magnetic layer 32 may be Some include B, it may not include.

Alloy having an L1 ₀ structure constituting the second magnetic layer 32 preferably contains a Fe or Co, and Pt.

The second magnetic layer 32 may further contain a grain boundary segregation material and have a granular structure.

Grain boundary segregation material contained in the second magnetic layer 32, nitrides such as VN, BN, SiN, TiN, carbides such as C and VC, borides such as BN, SiO ₂ , TiO ₂ , Cr ₂ O ₃ , Al. _{Oxides such as 2} O ₃ , Ta ₂ O ₅ , ZrO ₂ , Y ₂ O ₃ , CeO ₂ , MnO, TiO, ZnO and the like can be mentioned, and two or more of them may be used in combination.

When the number of laminated magnetic layers 3 is 3 or more, the magnetic layers other than the first magnetic layer 31 are the same as those of the second magnetic layer 32.

The magnetic recording medium 100 preferably has a protective layer formed on the magnetic layer 3.

The method for forming the protective layer is not particularly limited, and is, for example, an RF-CVD (Radio Frequency-Chemical Vapor Deposition) method in which a raw material gas composed of a hydrocarbon is decomposed by high-frequency plasma to form a film, and the protective layer is discharged from the filament. Examples thereof include an IBD (Ion Beam Deposition) method in which a raw material gas is ionized with electrons to form a film, and an FCVA (Filtered Chemical Vacum Arc) method in which a solid carbon target is used to form a film without using a raw material gas.

The thickness of the protective layer is preferably 1 nm to 6 nm. When the thickness of the protective layer is 1 nm or more, the floating characteristic of the magnetic head becomes good, and when it is 6 nm or less, the magnetic spacing becomes small and the SNR of the magnetic recording medium 100 improves.

The magnetic recording medium 100 may have a lubricant layer formed on the protective layer.

Examples of the material constituting the lubricant layer include fluororesins such as perfluoropolyether.

[Magnetic storage device]
The magnetic storage device of the present embodiment is not particularly limited as long as it has the magnetic recording medium of the present embodiment.

The magnetic storage device of the present embodiment includes, for example, a magnetic recording medium driving unit for rotating the magnetic recording medium of the present embodiment, a magnetic head provided with a near-field light generating element at the tip portion, and a magnetic head. It has a magnetic head drive unit for moving and a recording / playback signal processing system.

Further, the magnetic head has, for example, a laser light generating unit for heating the magnetic recording medium of the present embodiment and a waveguide for guiding the laser light generated from the laser light generating unit to the near-field light generating element.

FIG. 2 shows an example of the magnetic storage device of the present embodiment.

The magnetic storage device of FIG. 2 includes a magnetic recording medium 100, a magnetic recording medium driving unit 101 for rotating the magnetic recording medium 100, a magnetic head 102, and a magnetic head driving unit 103 for moving the magnetic head. It has a recording / reproducing signal processing system 104.

FIG. 3 shows an example of the magnetic head 102.

The magnetic head 102 has a recording head 208 and a reproduction head 211.

The recording head 208 generates near-field light of a main magnetic pole 201, an auxiliary magnetic pole 202, a coil 203 for generating a magnetic field, a laser diode (LD) 204 as a laser light generating unit, and a laser light 205 generated from the LD 204. It has a waveguide 207 that transmits to element 206.

The reproduction head 211 has a reproduction element 210 sandwiched between shields 209.

Hereinafter, examples of the present invention will be described. The present invention is not limited to the examples, and can be appropriately modified and implemented without changing the gist thereof.

(Example 1)
A 50 nm thick 50 atomic% Cr-50 atomic% Ti alloy film (third base layer) and a 25 nm thick 75 atomic% Co-20 atomic% Ta-5 atomic% B alloy film on a heat-resistant glass substrate. (Soft magnetic base layer) was formed in this order. Next, after heating the substrate to 250 ° C., a Cr film (second base layer) having a thickness of 10 nm was formed. At this time, a DC magnetron sputtering apparatus was used to form the third base layer, the soft magnetic base layer, and the second base layer.

Next, a first base layer was formed using an RF sputtering apparatus. Specifically, the sputtering gas pressure was set to 3 Pa and discharged for 12 seconds to form _{an MgO (1-x) film having a thickness of 2 nm.} At this time, MgO was used as the sputtering target, and argon containing 10% by volume of hydrogen was used as the sputtering gas.

After forming the first base layer, the oxygen deficiency amount X was measured by XPS.

Next, after heating the substrate to 520 ° C., a thickness of 60 mol% (47.5 at% Fe-47.5 at% Pt-5 at% B) -40 mol% C film (first magnetic layer) having a thickness of 3 nm was added. An 82 mol% (52 at% Fe-48 at% Pt) -18 mol% SiO ₂ film (second magnetic layer) having a thickness of 5 nm was formed in this order. At this time, a DC magnetron sputtering apparatus was used to form the first magnetic layer and the second magnetic layer.

Next, a carbon film (protective layer) having a thickness of 3 nm was formed by using an ion beam method, and then a perfluoropolyether film (lubricant layer) was formed by a coating method to obtain a magnetic recording medium. ..

(Example 2)
A magnetic recording medium was produced in the same manner as in Example 1 except that the first base layer was formed as follows using an RF sputtering apparatus.

Specifically, after discharging for 0.3 seconds at a sputter gas pressure of 3 Pa, discharging was performed for 12 seconds at a sputter gas pressure of 0.1 Pa to form _{an MgO (1-x) film having a thickness of 2 nm.} At this time, MgO was used as the sputtering target, and argon containing 10% by volume of hydrogen was used as the sputtering gas.

(Examples 3 to 7, Comparative Examples 1 to 4)
A magnetic recording medium was produced in the same manner as in Example 1 except that the film forming conditions of the first base layer and the first magnetic layer were changed (see Table 1).

(Examples 8 to 10)
A magnetic recording medium was produced in the same manner as in Example 2 except that the film forming conditions of the first base layer and the first magnetic layer were changed (see Table 1).

The sputter gas pressure in Examples 2 and 8 to 10 shown in Table 1 is the sputter gas pressure when discharging at 3 Pa for 0.3 seconds and then discharging for 12 seconds.

((001) orientation of magnetic layer)
Using an X-ray diffractometer (manufactured by Philips), the X-ray diffraction spectrum of the substrate after forming the second magnetic layer was measured, and the half width of the (200) peak of the FePt alloy was determined.

Incidentally, the magnetic layer (001) orientation was evaluated using the half width of FePt alloy (200) of a peak having an L1 ₀ structure contained in the magnetic layer. Here, the appearance angle 2θ of the (001) peak of the FePt alloy is not sufficiently large. Therefore, even if the low angle side is widened to the measurement limit when measuring the locking curve, the intensity of the (001) peak of the FePt alloy is not stable as compared with the case where the peak does not exist, and the half width is widened. Difficult to analyze. For such measurement reasons, it is difficult to evaluate the (001) orientation of the magnetic layer using the half width of the (001) peak of the FePt alloy. On the other hand, the (200) peak of the FePt alloy appears when the FePt alloy is oriented (001), but since the appearance angle 2θ is sufficiently large, it is suitable for evaluating the (001) orientation of the magnetic layer.

Table 1 shows the evaluation results of the (001) orientation of the magnetic layer of the magnetic recording medium.

表１から、実施例１〜１０の磁気記録媒体は、ＦｅＰｔ合金の（２００）ピークの半値幅が小さく、磁性層の（００１）配向性が高いことがわかる。

From Table 1, it can be seen that in the magnetic recording media of Examples 1 to 10, the half width of the (200) peak of the FePt alloy is small, and the (001) orientation of the magnetic layer is high.

On the other hand, in the magnetic recording media of Comparative Examples 1 and 2, since x of the first base layer is 0 to 0.05, the half width of the (200) peak of the FePt alloy is large, and the magnetic layer ( 001) Poor orientation.

Further, in the magnetic recording media of Comparative Examples 3 and 4, since x of the first base layer is 0 to 0.05 and the first magnetic layer does not contain B, the (200) peak of the FePt alloy The half-value width is large, and the (001) orientation of the magnetic layer is low.

1 Substrate 2 Base layer 21 First base layer 22 Second base layer 3 Magnetic layer 31 First magnetic layer 32 Second magnetic layer 100 Magnetic recording medium

Claims (4)

It has a substrate, a base layer, and a magnetic layer in this order.
The base layer is a general formula MgO _(1-X).
(In the formula, X is in the range of 0.07 to 0.25.)
It has a first base layer containing the compound represented by
The magnetic layer comprises an alloy having an L1 ₀ structure, the alloy having the L1 ₀ structure having a first magnetic layer including B,
The first base layer is a magnetic recording medium in contact with the first magnetic layer. The method for manufacturing the magnetic recording medium according to claim 1.
Magnetic recording including a step of forming the first base layer using a sputtering target containing MgO and a sputtering gas in which hydrogen is added to the inert gas in the range of 1% by volume to 20% by volume. Method of manufacturing the medium. The method for manufacturing the magnetic recording medium according to claim 1.
A step of forming the first base layer by discharging with a sputtering target containing MgO at a sputtering gas pressure of 1 Pa or more for 0.5 seconds or less and then discharging at a sputtering gas pressure of 0.5 Pa or less. A method for manufacturing a magnetic recording medium, including. A magnetic storage device having the magnetic recording medium according to claim 1.

Images