JP2009146507A - Perpendicular magnetic recording medium and magnetic recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a perpendicular magnetic recording device and a magnetic recording/reproducing device for recording and reproducing high-density information. <P>SOLUTION: The perpendicular magnetic recording medium 10 has at least a backing layer 2, an orientation control layer 9, a magnetic recording layer 6, and a protection layer 7 on a non-magnetic substrate. The orientation control layer 9 is composed by laminating at least two layers including a seed layer 3 and intermediate layers 4, 5 successively laminated from a non-magnetic substrate side 1. The seed layer 3 includes at least one kind of element selected from a group consisting of W, Ta, Nb, Mo as major constituents and has a film thickness of 0.3 to 2 nm; and the intermediate layer has (002)-orientation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a perpendicular magnetic recording medium and a magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium.

  In recent years, the range of application of magnetic recording devices such as magnetic disk devices, flexible disk devices, and magnetic tape devices has been remarkably increased, and the importance has increased, and the recording density of magnetic recording media used in these devices has increased. Significant improvements are being made. In particular, since the introduction of MR heads and PRML technology, the increase in surface recording density has become more intense, and in recent years, GMR heads, TuMR heads, etc. have also been introduced and continue to increase significantly.

  As described above, the magnetic recording medium is required to achieve higher recording density in the future. For this purpose, the magnetic recording layer must have higher coercive force, higher signal-to-noise ratio (SNR), and higher resolution. Is required. In the longitudinal magnetic recording method that has been widely used so far, as the linear recording density increases, the adjacent recording magnetic domains in the magnetization transition region dominated the self-demagnetization action that weakens each other's magnetization. In order to avoid this, it is necessary to increase the shape magnetic anisotropy by making the magnetic recording layer thinner and thinner.

  On the other hand, as the film thickness of the magnetic recording layer is reduced, the magnitude of the energy barrier for maintaining the magnetic domain and the magnitude of the thermal energy approach the same level, and the recorded magnetization amount is affected by the temperature. It is said that the phenomenon to be relaxed (thermal fluctuation phenomenon) cannot be ignored, and this determines the limit of the linear recording density.

  Under these circumstances, recently, an AFC (Anti Ferromagnetic Coupling) medium has been proposed as a technique to respond to the improvement of the linear recording density of the longitudinal magnetic recording system, and an effort has been made to avoid the problem of thermal magnetic relaxation, which is a problem in longitudinal magnetic recording. ing.

  In addition, the perpendicular magnetic recording technique is attracting attention as a promising technique for realizing a higher areal recording density in the future. While the conventional longitudinal magnetic recording system magnetizes the medium in the in-plane direction, the perpendicular magnetic recording system is characterized by magnetizing in the direction perpendicular to the medium surface. Accordingly, it is considered that the influence of the self-demagnetization action that hinders the achievement of a high linear recording density in the longitudinal magnetic recording method can be avoided, and it is considered suitable for higher density recording. Further, since a certain magnetic layer thickness can be maintained, it is considered that the influence of thermomagnetic relaxation, which is a problem in longitudinal magnetic recording, is relatively small.

  In general, a perpendicular magnetic recording medium is formed on a nonmagnetic substrate in the order of a seed layer, an intermediate layer, a magnetic recording layer, and a protective layer. In many cases, a lubricating layer is applied to the surface after forming a protective layer. In many cases, a magnetic film called a backing layer is provided under the seed layer. The intermediate layer is formed for the purpose of further improving the characteristics of the magnetic recording layer. The seed layer is said to function to adjust the crystal orientation of the intermediate layer and the magnetic recording layer and at the same time to control the shape of the magnetic crystal.

  In order to manufacture a perpendicular magnetic recording medium having excellent characteristics, the crystal structure of the magnetic recording layer is important. That is, in the perpendicular magnetic recording medium, the magnetic recording layer has a hexagonal close-packed structure in many cases, but the (002) crystal plane is parallel to the substrate surface. It is important that the crystal c-axis ([002] axis) be arranged in the perpendicular direction with as little disturbance as possible. However, although the perpendicular magnetic recording medium has an advantage that a relatively thick magnetic recording layer can be used, the total film thickness of the laminated thin film of the entire medium tends to be larger than that of the current longitudinal magnetic recording medium. There is a drawback that it easily includes factors that disturb the crystal structure in the process of lamination.

  In order to keep the crystal of the magnetic recording layer as undisturbed as possible, Ru having a hexagonal close-packed structure has been used for the intermediate layer of the perpendicular magnetic recording medium as in the conventional magnetic recording layer. Since the crystal of the magnetic recording layer is epitaxially grown on the Ru (002) crystal plane, a perpendicular magnetic recording medium with good crystal orientation can be obtained (see, for example, Patent Document 1).

  Further, a characteristic required for the seed layer located under the intermediate layer is to improve the crystal orientation of the intermediate layer. For this reason, conventionally, a seed layer having an amorphous material or a face-centered cubic structure has been used for the seed layer (see, for example, Patent Document 2). By using the seed layer of this amorphous material, the surface irregularities are reduced as compared with the backing layer, so that the intermediate layer is easily oriented. On the other hand, when a seed layer having a face-centered cubic structure is used, the (002) crystal plane of the hexagonal close-packed structure is preferentially oriented on the (111) crystal plane orientation of the face-centered cubic structure. Therefore, the total film thickness for obtaining the same orientation can be reduced as compared with the case of forming a film of Ru. On the other hand, in Patent Document 3, a material having a body-centered cubic structure is used for the seed layer.

However, in order to reduce the surface unevenness in the seed layer of amorphous material, and in the seed layer having the face-centered cubic crystal structure and the body-centered cubic structure, in order to improve the respective crystal orientation, However, a certain film thickness (5 nm or more) is required. If the seed layer is a non-magnetic material, increasing the seed layer thickness increases the distance between the magnetic recording layer and the soft magnetic backing layer, which weakens the magnetic flux from the head during recording, Write capability is reduced.
For example, Patent Document 4 describes a perpendicular magnetic recording medium using a W seed layer and a Ru alloy underlayer, and describes that the thickness of the seed layer is preferably 3 nm or more.

As described above, when an amorphous material, a crystalline material having a face-centered cubic structure, or a body-centered cubic structure is used for the seed layer, the perpendicular magnetic recording medium is excellent in recording and reproducing characteristics due to the increase in the thickness of the seed layer. It was not enough to get. For this reason, it is possible to achieve both the improvement of the crystal orientation of the magnetic recording layer and the maintenance and improvement of the writing ability during recording by reducing the film thickness between the backing layer and the magnetic recording layer, and the vertical direction that can be easily manufactured. A magnetic recording medium has been desired.
JP 2001-6158 A JP 2006-79718 A JP 2003-178812 A JP 2006-85825 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a perpendicular magnetic recording medium and a magnetic recording / reproducing apparatus capable of recording / reproducing high-density information.

In order to achieve the above object, the present invention is listed below.
(1) A perpendicular magnetic recording medium having at least a backing layer, an orientation control layer, a magnetic recording layer, and a protective layer on a nonmagnetic substrate, wherein the orientation control layer is a seed that is sequentially laminated from the nonmagnetic substrate side. The seed layer is composed of at least one element selected from the group consisting of W, Ta, Nb, and Mo as a main component, and has a film thickness. A perpendicular magnetic recording medium having a range of 0.3 nm to 2 nm and the intermediate layer being (002) -oriented.
(2) The perpendicular magnetic recording medium according to (1), wherein the seed layer does not have a (110) orientation as a main orientation.
(3) The perpendicular magnetic recording medium according to (1) or (2), wherein the ratio of the main component contained in the seed layer is 80 atomic% or more.
(4) The perpendicular magnetic recording medium according to any one of (1) to (3), wherein the backing layer has a soft magnetic amorphous structure.
(5) In any one of (1) to (4), at least one of the intermediate layers is mainly composed of Ru, Re, or an alloy material thereof, and has a hexagonal close-packed structure. The perpendicular magnetic recording medium described.
(6) At least one of the intermediate layers is composed of an alloy material with an element selected from the group of elements having at least one of the element groups having a face-centered cubic structure as a main component and having a body-centered cubic structure. Any of (1) to (4), characterized in that it has a (111) -oriented crystal structure and a layered irregular lattice (stacking fault) due to a mixture of a face-centered cubic structure and a body-centered cubic structure 2. A perpendicular magnetic recording medium according to 1.
(7) At least one of the intermediate layers is composed of an alloy material with an element selected from the group of elements having at least one of the element groups having a face-centered cubic structure as a main component and having a hexagonal close-packed structure. Any of (1) to (4), characterized in that it has a (111) -oriented crystal structure and a layered irregular lattice (stacking fault) by mixing a face-centered cubic structure and a hexagonal close-packed structure The perpendicular magnetic recording medium described.
(8) At least one of the magnetic recording layers has a granular structure formed by ferromagnetic crystal grains and nonmagnetic oxide crystal grain boundaries (1) to (7) The perpendicular magnetic recording medium according to any one of the above.
(9) A magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on the magnetic recording medium, wherein the magnetic recording medium is any one of (1) to (8). A magnetic recording / reproducing apparatus, which is a perpendicular magnetic recording medium.

  According to the present invention, the crystal structure of the magnetic recording layer, in particular, the crystal c-axis of the hexagonal close-packed structure is oriented with a small angular dispersion with respect to the substrate surface, and nonmagnetic between the soft magnetic backing layer and the magnetic recording layer. By suppressing the thickness of the layer to be thin, it is possible to provide a perpendicular magnetic recording medium and a magnetic recording / reproducing apparatus that improve the writing ability during recording and have excellent high recording density characteristics.

A perpendicular magnetic recording medium as an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view of a perpendicular magnetic recording medium according to this embodiment. FIG. 2 is a schematic diagram of the magnetic recording / reproducing apparatus of this embodiment. The following drawings are for explaining the configuration of the perpendicular magnetic recording medium and the magnetic recording / reproducing apparatus of the present embodiment. The size, thickness, dimensions, etc. of each part shown in the figure are the actual perpendicular magnetic recording. The dimensional relationship between the medium and the magnetic recording / reproducing apparatus may be different.
As shown in FIG. 1, the perpendicular magnetic recording medium 10 of this embodiment includes at least a soft magnetic backing layer (backing layer) 2, a seed layer 3, a first intermediate layer 4, and a second intermediate layer on a nonmagnetic substrate 1. 5, an orientation control layer 9, a magnetic recording layer 6, and a protective layer 7 are formed and roughly structured.
Hereinafter, each layer of the perpendicular magnetic recording medium 10 will be described in detail.

(Non-magnetic substrate)
The nonmagnetic substrate 1 of the present embodiment is not particularly limited, and an Al alloy substrate such as an Al-Mg alloy mainly composed of Al, ordinary soda glass, aluminosilicate glass, and amorphous glass. Any nonmagnetic substrate such as a substrate made of silicon, titanium, ceramics, sapphire, quartz, or various resins can be used.
Further, it is preferable to use a glass substrate such as an Al alloy substrate, crystallized glass, or amorphous glass. In the case of a glass substrate, a mirror polished substrate or a surface roughness (Ra) of less than 1 (Å) is low. A Ra substrate or the like is more preferable. In addition, if it is mild, the texture may be contained.

  In the manufacturing process of the magnetic disk, the substrate is usually first cleaned and dried. In the present invention, it is desirable to perform cleaning and drying before formation from the viewpoint of ensuring the adhesion of each layer. Cleaning includes not only water cleaning but also cleaning by etching (reverse sputtering). Also, the substrate size is not particularly limited.

(Lining layer)
The soft magnetic backing layer 2 of the present embodiment functions to guide a recording magnetic field from the head and efficiently apply a perpendicular component of the recording magnetic field to the magnetic recording layer 6 when recording a signal on the medium. The soft magnetic backing layer 2 is made of a material having so-called soft magnetic characteristics such as an FeCo alloy, a CoZrNb alloy, or a CoTaZr alloy. Furthermore, it is particularly preferable that the soft magnetic backing layer 2 has an amorphous (noncrystalline) structure. This is because by making the soft magnetic backing layer 2 an amorphous structure, it is possible to prevent the surface roughness (Ra) from increasing, to reduce the flying height of the head, and to further increase the recording density. .
Furthermore, the soft magnetic backing layer 2 is not limited to a single layer, and a non-magnetic thin film such as Ru is sandwiched between the two layers and the soft magnetic layers are antiferromagnetically coupled (AFC). It can also be applied. The total film thickness of the soft magnetic backing layer 2 is preferably about 20 (nm) to 120 (nm), and can be appropriately determined depending on the balance between the recording / reproducing characteristics and the overwrite (OW) characteristics.

(Orientation control layer)
The orientation control layer 9 of this embodiment is provided on the backing layer 2 and controls the orientation of the film immediately above the orientation control layer 9. The orientation control layer 9 is composed of a plurality of layers, and is composed of a seed layer 3 and an intermediate layer composed of a first intermediate layer 4 and a second intermediate layer 5 laminated from the nonmagnetic substrate 1 side. Yes. In the present specification, the first intermediate layer 4 and the second intermediate layer 5 may be collectively referred to as an intermediate layer.

(Seed layer)
For the seed layer 3, a material containing as a main component any one or more elements selected from the group consisting of W, Ta, Nb, and Mo can be used. The main component refers to an element having the largest content among the elements constituting the seed layer 3.
Here, for the intermediate layer formed on the seed layer 3, for example, Ru having (002) orientation and a hexagonal close-packed structure is generally used. In this case, a material having a body-centered cubic structure such as W, Ta, Nb, and Mo is not used for the normal seed layer 3. The reason is as follows. That is, when these materials having a body-centered cubic structure are used as the seed layer 3, the seed layer 3 is (110) -oriented, which is the closest packed surface. Thus, when an intermediate layer is formed on the (110) -oriented seed layer 3, the material such as Ru having a hexagonal close-packed structure is (101) -oriented instead of the (002) crystal plane which is the closest-packed surface. End up. Therefore, the magnetic recording layer 6 formed on such a (101) -oriented intermediate layer cannot be (002) -oriented in the vertical orientation.

In this embodiment, the reason why the above-mentioned W, Ta, Nb, and Mo can be used as the material of the seed layer 3 is that this layer is a thin film and the melting point of the material constituting this layer is high. This is because the crystals of this layer are randomly oriented and the (101) orientation of the intermediate layer formed on the seed layer 3 is suppressed. That is, the material of the seed layer 3 of this embodiment is preferably a thin film of a material having a high melting point of 2000 ° C. or higher.
Further, the surface of the thin film seed layer 3 made of a high melting point material having a randomly oriented body-centered cubic structure as described above has less surface irregularities than the surface of a seed layer made of a normal amorphous material. For this reason, the crystal | crystallization of the intermediate | middle layer formed into a film on this seed layer 3 can obtain the outstanding orientation.
If the seed layer 3 is (110) oriented, periodic diffraction spots are observed in the observation of the electron beam diffraction image. On the other hand, if the seed layer 3 is in a random orientation, not a diffraction spot but a diffraction ring is observed.

The film thickness of the seed layer 3 is in the range of 0.3 (nm) to 2 (nm). Further, the film thickness of the seed layer 3 is preferably in the range of 0.3 (nm) to 1.5 (nm). By setting the film thickness of the seed layer 3 within this range, the (110) orientation of the seed layer 3 can be suppressed, and the intermediate layer formed on the seed layer 3 can be suppressed from being (101) oriented. . That is, the seed layer 3 is randomly oriented without the (110) crystal plane being the main orientation. When an intermediate layer is provided on the seed layer 3, the intermediate layer can have a good (002) orientation.
Further, the ratio of the main component element contained in the seed layer 3 is preferably 80 atomic% or more. If the ratio of the main component is less than 80 atomic%, the melting point is too low and the random orientation when the thin film is formed deteriorates.

(Middle layer)
The intermediate layer of this embodiment is a first intermediate layer 4 and a second intermediate layer 5 from the nonmagnetic substrate 1 side, and is composed of at least two intermediate layers.
Since the crystal orientation of the magnetic recording layer 6 stacked on the intermediate layer is substantially determined by the crystal orientation of the intermediate layer, the control of the orientation of the intermediate layer is extremely important in the manufacture of the perpendicular magnetic recording medium 10. .

(First intermediate layer)
The first intermediate layer 4 is formed on the seed layer 3. Examples of the constituent material of the first intermediate layer 4 include Ru, Re, and alloys having stacking faults.
That is, the first intermediate layer 4 is preferably made of Ru, Re, or an alloy material thereof, and has a hexagonal close-packed structure.
In addition, the first intermediate layer 4 is composed of an alloy material with an element selected from the group of elements having a body-centered cubic structure and having at least one element as a main component among the group of elements having a face-centered cubic structure, 111) Oriented crystal structure and layered irregular lattice (stacking fault) due to mixing of face-centered cubic structure and body-centered cubic structure are preferable.
The first intermediate layer 4 is composed of an alloy material with an element selected from an element group having a hexagonal close-packed structure as a main component and at least one element group having a face-centered cubic structure. It is preferable to have a 111) oriented crystal structure and a layered irregular lattice (stacking fault) by mixing a face-centered cubic structure and a hexagonal close-packed structure.
In any of the above cases, the first intermediate layer 4 can form excellent orientation and fine crystal grains.

The thickness of the first intermediate layer 4 is preferably in the range of 1 to 15 nm, and more preferably in the range of 5 to 10 nm. It is preferable for the film thickness of the first intermediate layer 4 to be in the range of 1 to 15 nm because improvement in crystal orientation of the first intermediate layer 4 and coalescence of crystal grains can be suppressed.
Note that, when the first intermediate layer 4 is formed, the film is preferably formed under a low gas pressure, and is preferably 1 Pa or less. It is preferable that the gas pressure during film formation of the first intermediate layer 4 is 1 Pa or less because the crystal orientation of the first intermediate layer 4 can be improved.

(Second intermediate layer)
The second intermediate layer 5 of the present embodiment is formed on the first intermediate layer 4, has a hexagonal close-packed structure or a face-centered cubic structure, and crystal grains of the second intermediate layer are oxide, nitride It is preferable to be separated from the surrounding crystal grains by an object or a void. This is preferable because the enlargement of the grain size (coarse crystal grains) due to the coalescence of the crystal grains of the second intermediate layer can be suppressed, and is preferable as a magnetic recording layer described later formed on the second intermediate layer 5 6 is preferable because it can be formed into fine crystal grains.

As described above, in order to improve the crystal orientation of the entire intermediate layer, it is preferable that the first intermediate layer 4 which is the initial growth portion of the intermediate layer has a low gas pressure during film formation.
However, if the film growth is continued in a state where the gas pressure during film formation is low, the crystals of the plurality of intermediate layers on the crystal of the seed layer 3 are coalesced with each other during the film growth. In the crystal of the magnetic recording layer 6 formed on the crystal of the combined intermediate layer, since one crystal is epitaxially grown, there is a problem that the crystal grain size is increased to about the crystal grain size of the combined intermediate layer. is there.

Therefore, in the second intermediate layer 5, the gas pressure during film formation is preferably 1.5 Pa or more, and more preferably 3 Pa or more. It is preferable to set the gas pressure at the time of film formation of the second intermediate layer 5 to 1.5 Pa, since voids are generated between the crystal grains of the intermediate layer and coalescence of the crystal grains can be suppressed.
In addition, when surrounding the crystal grains of the second intermediate layer 5 with an oxide or nitride grain boundary or when having a granular structure, not only can the coalescence of the crystal grains of the second intermediate layer 5 be suppressed, By increasing the boundary width, crystal grains can be made finer. In this embodiment, by suppressing the coalescence of the crystal grains of the intermediate layer 3, the crystal grains of one fine second intermediate layer 5 are epitaxially grown on the crystal grains of one fine first intermediate layer 4. Further, since the crystal grains of one magnetic recording layer 6 are epitaxially grown on the crystal grains of one fine second intermediate layer 5, both the high density of the magnetic recording layer 6 and the miniaturization of the grain size are achieved. can do.

(Magnetic recording layer)
The magnetic recording layer 6 of the present embodiment is a layer on which signals are actually recorded, and the easy magnetization axis (crystal c axis) is oriented mainly perpendicularly to the nonmagnetic substrate 1. Therefore, finally, the crystal structure and magnetic properties of the magnetic recording layer 6 determine recording and reproduction.
Examples of the material of the magnetic recording layer 6, CoCr, CoCrPt, CoCrPtB, CoCrPtB-X, CoCrPtB-X-Y, CoCrPt-O, CoCrPt-SiO 2, CoCrPt-Cr 2 O 3, CoCrPt-TiO 2, CoCrPt-ZrO ₂ , CoCrPt—Nb ₂ O ₅ , CoCrPt—Ta ₂ O ₅ , CoCrPt—Ai ₂ O ₃ , CoCrPt—B ₂ O ₃ , CoCrPt—WO ₂ , CoCrPt—WO _3, etc. Note that X in the above constituent materials represents Ru, W, or the like, and Y represents Cu, Mg, or the like.
In particular, a magnetic material containing an oxide such as O, SiO ₂ , Cr ₂ O ₃ , TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and a Co alloy such as CoCrPt as a constituent material of the perpendicular magnetic recording layer 6. In the case of using a layer (oxide magnetic layer), it is preferable that the non-magnetic oxide adopts a granular structure surrounding the ferromagnetic Co crystal grains. Thereby, the magnetic interaction between Co crystal grains is weakened, and noise can be reduced. In the present embodiment, the perpendicular magnetic recording layer 6 preferably has a granular structure in which at least one layer is formed of ferromagnetic crystal grains and non-magnetic oxide crystal grain boundaries.

  The crystal structure of the magnetic recording layer 6 is a hexagonal close-packed structure, and its (002) crystal plane is parallel to the substrate surface, that is, the crystal c-axis ([002] axis) is perpendicular. It is preferable that the arrangement is as undisturbed as possible.

As a method for evaluating the crystal structure, the full width at half maximum of the rocking curve can be used. First, a film formed on a substrate is applied to an X-ray diffractometer, and a crystal plane parallel to the substrate surface is analyzed. When the sample contains a film having a hexagonal close-packed structure like the above-described intermediate layer and magnetic recording layer 6, a diffraction peak corresponding to the crystal plane is observed. In the case of the perpendicular magnetic recording medium 10 using a Co-based alloy, since the c-axis [002] direction of the hexagonal close-packed structure is oriented perpendicular to the substrate surface, a peak corresponding to the (002) crystal plane is observed. Will be.
Next, the optical system is swung with respect to the substrate surface while maintaining the Bragg angle for diffracting the (002) crystal plane. At this time, one diffraction peak (called a rocking curve) can be drawn by plotting the diffraction intensity of the (002) crystal plane against the angle at which the optical system is inclined.
When the (002) crystal planes are very well parallel to the substrate surface, a sharp rocking curve is obtained. On the other hand, when the orientation of the (002) crystal plane is widely dispersed, a broad rocking curve is obtained.
Therefore, the full width at half maximum Δθ50 of the rocking curve can be used as an index of the quality of the crystal orientation of the perpendicular magnetic recording medium 10. It can be determined that the smaller the value of Δθ50 is, the better the crystal orientation of the perpendicular magnetic recording medium 10 is.

For forming the backing layer 2, seed layer 3, first intermediate layer 4, second intermediate layer 5, and magnetic recording layer 6, the DC magnetron sputtering method or the RF sputtering method is usually used. Further, RF bias, DC bias, pulse DC, pulse DC bias, O ₂ gas, H ₂ O gas, H ₂ gas, and N ₂ gas can be used.
The sputtering gas pressure at the time of film formation can be appropriately determined so that the characteristics are optimized for each layer, and is generally controlled in the range of about 0.1 to 30 (Pa), and the performance of the perpendicular magnetic recording medium 10 is improved. Adjust while watching.

In the present embodiment, as a method for forming the seed layer 3, not only sputtering by general Ar gas but also reactive sputtering in which N ₂ gas or O ₂ gas is added to Ar gas is applied as a useful method. can do. In reactive sputtering, the deposition rate of the seed layer 3 is reduced by adding N ₂ gas or O ₂ gas to Ar gas, so that the unevenness of the surface of the seed layer 3 is further reduced, and the orientation of the intermediate layer is improved. Can be improved. Further, by using Kr gas instead of Ar gas, the surface unevenness can be reduced and the orientation of the intermediate layer can be improved.

(Protective layer)
The protective layer 7 of this embodiment is provided to protect the perpendicular magnetic recording medium 10 from damage due to contact between the magnetic head and the perpendicular magnetic recording medium 10. As a material of the protective layer 7, a carbon film, a SiO ₂ film, or the like is preferable, and a carbon film is particularly preferable.
A sputtering method, a plasma CVD method, or the like can be used to form the protective film of the protective layer 7, and the plasma CVD method is particularly preferable. Furthermore, it is possible to use a magnetron plasma CVD method.
The film thickness of the protective layer 7 is in the range of 1 to 10 (nm), preferably in the range of 2 to 6 (nm), more preferably in the range of 2 to 4 (nm).

<Magnetic recording / reproducing device>
Next, a magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium 10 will be described.
FIG. 2 shows an example of a magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium 10. As shown in FIG. 2, the magnetic recording / reproducing apparatus 100 records information on the perpendicular magnetic recording medium 10 having the above-described configuration, a medium driving unit 101 that rotationally drives the perpendicular magnetic recording medium 10, and the perpendicular magnetic recording medium 10. A magnetic head 102 for reproduction, a head drive unit 103 for moving the magnetic head 102 relative to the perpendicular magnetic recording medium 10, and a recording / reproduction signal processing system 104 are provided.

  The recording / reproducing signal processing system 104 can process data input from the outside and send the recording signal to the magnetic head 102, and can process the reproducing signal from the magnetic head 102 and send the data to the outside. It is like that.

  The magnetic head 102 used in the magnetic recording / reproducing apparatus 100 of the present embodiment has not only an MR (Magneto Resistance) element using an anisotropic magnetoresistive effect (AMR) as a reproducing element but also a giant magnetoresistive effect (GMR). A magnetic head suitable for a higher recording density having a GMR element used, a TuMR element using a tunnel effect, or the like can be used.

  As described above, in the present embodiment, since the seed layer 3 has a film thickness of 0.3 (nm) or more and 2 (nm) or less, the seed layer 3 is a random orientation in which the (110) orientation is not the main orientation. It can be. Then, when an intermediate layer is provided on the seed layer 3, it is clear that the intermediate layer has a good (002) orientation. Therefore, by adopting such a configuration, it becomes possible to reduce the film thickness of the seed layer 3 to less than half of the conventional one, thereby reducing the distance between the magnetic recording / reproducing head and the soft magnetic backing layer 2. Thus, the perpendicular magnetic recording medium 10 having excellent magnetic recording / reproducing characteristics can be provided.

  Further, the orientation control layer 9 of the perpendicular magnetic recording medium 10 of the present embodiment is also applicable to new perpendicular recording media such as ECC media, discrete track media, and pattern media, where further improvement in recording density is expected in the future. Is possible.

  As described above, according to the present invention, the crystal structure of the magnetic recording layer 6, particularly the crystal c-axis of the hexagonal close-packed structure is oriented with a small angular dispersion with respect to the substrate surface, and the soft magnetic backing layer 2. A perpendicular magnetic recording medium and a magnetic recording / reproducing apparatus having improved recording performance and excellent high recording density characteristics are provided by suppressing the film thickness of the nonmagnetic layer between the magnetic recording layer 6 and the magnetic recording layer 6 to be thin. be able to.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

(Example 1, Comparative Example 1)
The vacuum chamber in which the glass substrate for HD was set was evacuated to 1.0 × 10 ⁻⁵ (Pa) or less in advance.
Next, a soft magnetic backing layer Co ₁₀ Ta ₅ Zr was formed on this substrate in an Ar atmosphere with a gas pressure of 0.6 (Pa) so as to have a film thickness of 50 (nm) using a sputtering method. .

Next, 1 (nm) each of W, Ta, Mo, and Nb, which are elements having a high melting point and a body-centered cubic structure, are formed as seed layers in an Ar atmosphere, and Ru is formed as a first intermediate layer. Each film was formed in an Ar atmosphere at 5 (nm) and a gas pressure of 0.6 (Pa). Further, as the second intermediate layer, Ru was formed in an Ar atmosphere at a gas pressure of 5 (Pa) so that each film thickness was 15 (nm) (Example 1-1 to Example 1-4). .
In the comparative example, Ar, which has a gas pressure of 0.6 (Pa), has a W, Ta, Mo, and Nb thickness of 3 (nm), 5 (nm), and 10 (nm), respectively, as a seed layer. Example 1-1 was applied to a film formed in an atmosphere and a film formed in an Ar atmosphere having a gas pressure of 0.6 (Pa) so that V and Cr each have a film thickness of 1 (nm). To 1-4, the first intermediate layer and the second intermediate layer were formed in an Ar atmosphere (Comparative Example 1-1 to Comparative Example 1-14).
Further, 91 (Co ₁₀ Cr ₂₀ Pt) -9 (SiO ₂ ) (mol%) is formed as a magnetic recording layer in a thickness of 12 (nm) in an Ar atmosphere with a gas pressure of 5 (Pa). A perpendicular magnetic recording medium was manufactured by depositing 4 nm in an atmosphere.

For the obtained perpendicular magnetic recording media (Example 1-1 to Example 1-4 and Comparative Example 1-1 to Comparative Example 1-14), a lubricant was applied, and a read / write analyzer 1632 and spin made by GUZIK, USA. Recording / reproduction characteristics were evaluated using the stand S1701MP.
Thereafter, the magnetostatic characteristics were evaluated using a Kerr measuring device.
Further, in order to investigate the crystal orientation of the Co-based alloy in the magnetic recording layer, the rocking curve of the magnetic layer was measured with an X-ray diffractometer.

  From each measurement, the results of high signal-to-noise ratio: SNR, coercive force: Hc, and Δθ50 for the examples and comparative examples are listed in Table 1. Each parameter is an index widely used when evaluating the performance of a perpendicular magnetic recording medium. 1 Oe is about 79 A / m.

  From Table 1, when the film thickness of the seed layer made of the elements W, Ta, Mo, and Nb having a high melting point body-centered cubic structure is 3 (nm) or more, the orientation of the magnetic recording layer is deteriorated and the SNR is also lowered. . This is considered to be because the seed layer is (110) -oriented with a body-centered cubic structure by increasing the thickness of the seed layer, and the Ru of the intermediate layer is (101) -oriented instead of (002) -oriented. . In particular, when the film thickness was 10 (nm), the deterioration of the orientation of Ru in the intermediate layer and the magnetic recording layer thereon was so severe that the value of Δθ50 could not be measured. On the other hand, when V or Cr, which is an element having a body-centered cubic structure with a melting point of 2000 (° C.) or less, is used as a seed layer, Examples 1-1 to Examples using a high melting point material as a seed layer Compared with 1-4, the orientation of the magnetic recording layer was poor and only a low SNR value was obtained. This is presumably because the irregularities on the surface of the seed layer are larger than those of the high melting point seed layer.

(Example 2, comparative example 2)
Similarly to Example 1, a soft magnetic layer was formed on a glass substrate. As a seed layer, W and Mo having a high melting point body-centered cubic structure have a gas pressure of 0.6 (Pa) so that the film thicknesses are 0.5 (nm), 1 (nm), and 2 (nm), respectively. ) In an Ar atmosphere (Example 2-1 to Example 2-6).
In the comparative example, as the seed layer, Pt having a face-centered cubic structure, Ti having a hexagonal close-packed structure, and Ni ₅₀ Nb which is an amorphous material have a thickness of 0.5 (nm), 1 (nm), Film formation was performed in an Ar atmosphere with a gas pressure of 0.6 (Pa) so as to be 2 (nm), 5 (nm), and 10 (nm) (Comparative Example 2-1 to Comparative Example 2-15).

Next, Ru is formed as a first intermediate layer in an Ar atmosphere at a gas pressure of 0.6 (Pa) so that the film thickness is 10 (nm), and further, Ru-2SiO is formed as a second intermediate layer. ₂ (mol%) was deposited in an Ar atmosphere with a gas pressure of 10 (Pa) so that the film thickness was 10 (nm).
Further, 91 (Co ₁₀ Cr ₂₀ Pt) -9 (SiO ₂ ) as a magnetic recording layer and a carbon film as a protective layer were formed in the same manner as in Example 1 to manufacture a perpendicular magnetic recording medium.
From Guzik measurement, high signal-to-noise ratio: SNR and writing ability: OW, Kerr measurement, coercive force: Hc, X-ray diffraction measurement, Δθ50, Example 2-1 to Example 2-6 and Comparative Example 2-1 It calculated | required with respect to Comparative Example 2-15. The results are listed in Table 2.

  From Table 2, when Pt, which is a crystal having a face-centered cubic structure, is used as the seed layer (Comparative Example 2-1 to Comparative Example 2-5), or Ti, which is a hexagonal close-packed structure crystal, is used ( In Comparative Examples 2-6 to 2-10), the orientation of the seed layer itself is improved by increasing the thickness of the seed layer. When the seed layer thickness is 10 (nm), the value of Δθ50 of the magnetic recording layer is approximately the same as that of Example 2-1 to Example 2-6. However, since the film thickness between the backing layer and the magnetic recording layer is increased and the magnetic flux of the backing layer is weakened, the OW characteristics are deteriorated, and the SNR is inferior to the embodiment. On the other hand, the same applies to Comparative Examples 2-11 to 2-15, which are amorphous seed layers. By increasing the thickness of the seed layer, the irregularities on the surface of the seed layer are reduced, so the orientation of Ru is improved. However, it was confirmed that neither the orientation nor the SNR reached the examples.

(Example 3)
Similarly to Example 1, a soft magnetic layer was formed on a glass substrate. Next, Mo is deposited as the seed layer so that the film thicknesses are 1 (nm) and 2 (nm), respectively, and the gas pressure is 0.6 (Pa) when the total gas flow rate is Ar 100%. The film was formed in an atmosphere where the flow rate of N ₂ gas was 0, ₂₀ , 40, 60% and the flow rate of O ₂ gas was 2% (Example 3-1 to Example 3-10).

Next, Ru is formed as a first intermediate layer in an Ar atmosphere at a gas pressure of 0.6 (Pa) so that the film thickness is 10 (nm), and further, Ru-2SiO is formed as a second intermediate layer. ₂ (mol%) was deposited in an Ar atmosphere with a gas pressure of 10 (Pa) so that the film thickness was 10 (nm).
Further, 91 (Co ₁₀ Cr ₂₀ Pt) -9 (SiO ₂ ) as a magnetic recording layer and a carbon film as a protective layer were formed in the same manner as in Example 1 to manufacture a perpendicular magnetic recording medium. Table 3 shows the results of SNR, Hc, and delta θ50 as a list.

From Table 3, in Example 3, the crystal orientation of the magnetic recording layer was improved and the SNR was improved by adding N ₂ gas or O ₂ gas to 100% Ar gas. This is presumably because the surface roughness of the seed layer was reduced by the additive gas.
From the above, also in the combination of the seed layer thickness and the flow rate of the additive gas as shown in Example 3-1 to Example 3-10, the writing ability at the time of recording is improved and the high recording density characteristic is excellent. A perpendicular magnetic recording medium could be manufactured.

FIG. 1 is a schematic sectional view showing a perpendicular magnetic recording medium of this embodiment. FIG. 2 is a schematic diagram showing an example of the magnetic recording / reproducing apparatus of the present embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic board | substrate, 2 ... Backing layer, 3 ... Seed layer, 4 ... 1st intermediate | middle layer, 5 ... 2nd intermediate | middle layer, 6 ... Magnetic recording layer, 7 * ..Protective layer, 9 ... orientation control layer, 10 ... perpendicular magnetic recording medium, 100 ... magnetic recording / reproducing apparatus, 101 ... medium drive unit, 102 ... magnetic head, 103 ... Head drive unit, 104... Recording / reproducing signal system

Claims (9)

A perpendicular magnetic recording medium having at least a backing layer, an orientation control layer, a magnetic recording layer, and a protective layer on a nonmagnetic substrate,
The orientation control layer is composed of a laminate of two or more layers including a seed layer and an intermediate layer sequentially laminated from the nonmagnetic substrate side,
The seed layer includes as a main component any one or more elements selected from the group consisting of W, Ta, Nb, and Mo, and has a thickness in the range of 0.3 nm to 2 nm, and
A perpendicular magnetic recording medium, wherein the intermediate layer is (002) -oriented.   The perpendicular magnetic recording medium according to claim 1, wherein the seed layer does not have a (110) orientation as a main orientation.   3. The perpendicular magnetic recording medium according to claim 1, wherein a ratio of an element of a main component contained in the seed layer is 80 atomic% or more.   The perpendicular magnetic recording medium according to any one of claims 1 to 3, wherein the backing layer has a soft magnetic amorphous structure.   5. The vertical according to claim 1, wherein at least one of the intermediate layers is composed mainly of Ru, Re, or an alloy material thereof, and has a hexagonal close-packed structure. Magnetic recording medium.   At least one of the intermediate layers is composed of an alloy material composed mainly of at least one element group having a face-centered cubic structure and an element selected from the element group having a body-centered cubic structure. 111) The crystal structure to be oriented and a layered irregular lattice (stacking fault) due to a mixture of a face-centered cubic structure and a body-centered cubic structure are combined. Perpendicular magnetic recording medium.   At least one of the intermediate layers is composed of an alloy material with an element selected from an element group having at least one element group having a face-centered cubic structure as a main component and having a hexagonal close-packed structure, The vertical structure according to any one of claims 1 to 4, which has a 111) oriented crystal structure and a layered irregular lattice (stacking fault) formed by mixing a face-centered cubic structure and a hexagonal close-packed structure. Magnetic recording medium.   8. The magnetic recording layer according to claim 1, wherein at least one of the magnetic recording layers has a granular structure formed of ferromagnetic crystal grains and nonmagnetic oxide crystal grain boundaries. 2. A perpendicular magnetic recording medium according to 1. A magnetic recording / reproducing apparatus comprising a magnetic recording medium and a magnetic head for recording / reproducing information on the magnetic recording medium,
A magnetic recording / reproducing apparatus, wherein the magnetic recording medium is a perpendicular magnetic recording medium according to any one of claims 1 to 8.

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