JP2006185566A - Perpendicular magnetic recording medium and magnetic recording / reproducing apparatus using the same - Google Patents

Abstract

By improving the C-axis orientation of a perpendicular magnetic recording layer, thermally stable high-density perpendicular magnetic recording is performed with good SNR characteristics. An amorphous alloy containing at least Ni is provided. Magnetic crystal grains containing at least one element of Fe and Co and at least one element of Pt and Pd and having an L1 ₀ structure and mainly (001) orientation are formed on the base layer having the base film. A magnetic recording layer is formed.
[Selection] Figure 1

Description

  The present invention relates to a perpendicular magnetic recording medium used in a hard disk device or the like using magnetic recording technology, and a magnetic recording / reproducing apparatus.

  With the recent improvement in computer processing speed, a magnetic storage device (HDD) that stores and reproduces information is required to have high speed and high density. Currently, the mainstream recording method for HDDs is the in-plane recording method in which the magnetization is directed in the medium in-plane direction. However, considering higher density, perpendicular magnetic recording is suitable because the demagnetizing field in the vicinity of the magnetization reversal boundary is small and sharp reversal magnetization can be obtained. Further, with respect to thermal fluctuations that have become a problem in recent years for magnetic recording media, the perpendicular magnetic recording medium can be set to have a larger film thickness than the in-plane magnetic recording medium, so that deterioration can be suppressed to a low level.

  As the perpendicular magnetic recording layer, conventionally, CoCr-based disordered alloy magnetized films including CoCrPt have been mainly studied. However, considering that the thermal fluctuation can be a problem even in a perpendicular magnetic recording medium, a material having a greater perpendicular magnetic anisotropy than a conventional CoCr-based material is desired.

An example of such a material is an ordered phase alloy material in which a magnetic substance of Fe and Co and a noble metal element of Pt and Pd form an ordered phase. For example L1 ₀ FePt and CoPt ordered alloys having a crystal structure of, the C-axis direction ((001) direction), a large magnetic anisotropy of each ^{7 × 10 7 erg / cc,} 4 × 10 7 erg / cc It is known to have. By using these materials as the recording layer, it is expected to realize a perpendicular magnetic recording medium having high thermal fluctuation resistance. However, in order to use these materials as the perpendicular magnetic recording layer, it is necessary to orient the C axis, which is the easy axis of magnetization, perpendicular to the surface of the perpendicular magnetic recording layer. As a method for producing a magnetic recording layer oriented along the C axis, for example, there is a method in which a base layer made of a compound crystal such as (100) oriented MgO or NiO is provided between the substrate and the magnetic recording layer (for example, Patent Document 1). reference). However, all of these compound crystals have a large lattice mismatch with the ordered alloy crystal grains, and therefore the C-axis orientation is lowered, and as a result, the signal-to-noise ratio (SNR) in the recording / reproducing characteristics is lowered. There was a problem such as. Furthermore, when applied to a so-called vertical double-layer film medium provided with a soft magnetic backing layer, the orientation plane of the underlayer made of this compound crystal is greatly affected by the crystallinity and orientation plane of the soft magnetic backing layer, so It was difficult to control the C-axis orientation of the magnetic recording layer. As a method other than using the compound underlayer, for example, there is a method using Ta as a seed layer. As a method of using Ta as a seed layer, after heating the glass substrate to 150 ° C., the substrate surface is coated with Ta, taken out of the film formation chamber and left in the atmosphere for 24 hours, and then again in the film formation chamber. There is a method in which a substrate is introduced and heated to 250 ° C., and then an underlayer, a magnetic recording layer, and a protective layer are sequentially formed. However, the process of taking out the medium from the film forming chamber and leaving it in the atmosphere for 24 hours as described above has a problem that the productivity is low and the cost is increased.
JP-A-11-353648

The present invention has been made in view of the above-described circumstances. By improving the C-axis orientation of the perpendicular magnetic recording layer, thermally stable high-density perpendicular magnetic recording can be performed with good SNR characteristics. With the goal.

A perpendicular magnetic recording medium according to the present invention includes a substrate,
An underlayer having a first underlayer formed on the substrate and including an amorphous alloy containing Ni;
Magnetic recording comprising magnetic crystal grains formed on the underlayer and containing at least one element of Fe and Co and at least one element of Pt and Pd and having an L1 ₀ structure and mainly (001) orientation And a layer.

A magnetic recording / reproducing apparatus according to the present invention includes a substrate, a base layer having a first base film formed on the substrate and including an amorphous alloy containing Ni, and formed on the base layer, Fe and contains at least one element of at least one element of Pt and Pd of Co, have an L1 ₀ structure, and a perpendicular magnetic recording medium comprising a magnetic recording layer containing predominantly (001) -oriented magnetic crystal grains, the recording And a reproducing head.

  According to the present invention, it is possible to provide a magnetic recording medium having good recording / reproducing characteristics, good SNR characteristics and thermal stability and capable of high-density recording.

The perpendicular magnetic recording medium of the present invention includes a substrate, an at least one underlayer formed on the substrate, and a perpendicular magnetic recording layer formed on the underlayer, and the underlayer contains Ni. The perpendicular magnetic recording layer includes a magnetic crystal grain having an L1 ₀ structure, and is selected from at least one element selected from Fe and Co, and Pt and Pd. The main component is at least one kind of element, and the magnetic crystal grains are mainly (001) -oriented.

  A magnetic recording / reproducing apparatus of the present invention includes the perpendicular magnetic recording medium and a recording / reproducing head.

  Hereinafter, the present invention will be specifically described with reference to the drawings.

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

As shown in the figure, this perpendicular magnetic recording medium 10 has a structure in which a base film 2 and a perpendicular magnetic recording layer 3 are sequentially laminated on a substrate 1. The base film 2 includes an amorphous alloy containing Ni. The magnetic recording layer 3 is made of L1 ₀ structure as the owner of the (001) oriented magnetic crystal grains, and is used as the main component magnetic metal element and noble metal element. The magnetic metal is at least one selected from Fe and Co, and the noble metal element is at least one selected from the group consisting of Pt and Pd.

  Here, the main component used in the present invention refers to an element having the highest atomic ratio among the elements constituting the alloy, or an element group having the highest atomic ratio. To do.

FIG. 2 is a diagram for explaining the L1 ₀ structure of the magnetic recording layer used in the present invention.

As shown in the figure, in the L1 ₀ structure, different atoms such as Fe and Pt are regularly and alternately arranged on a crystal axis such as a plane perpendicular to the C axis in this case. Crystal structure. On the other hand, in an irregular phase that does not take a regular structure, the crystal structure takes a face-centered cubic lattice, and each atom occupies lattice points in a disorderly manner.

Whether the crystal grains constituting the magnetic recording layer has the L1 ₀ structure it can be confirmed by a general X-ray diffraction apparatus. If peaks (regular lattice reflections) such as (001) and (003) that are not observed in the irregular face-centered cubic lattice (FCC) can be observed at diffraction angles that coincide with the plane spacing, an L1 ₀ structure exists. It can be said that.

  Specifically, the intensity of the peaks representing the (001) and (003) planes may be any intensity that can be observed as a peak superior to the background level. Even if a peak representing another orientation plane such as (111) is observed, if the peak representing the (001) plane can be observed at a relatively large intensity, for example, 100 times or more, the C axis is oriented perpendicular to the film plane. It can be said that. Further, when the magnetic particle is reduced to about 10 nm and the correlation (coherency) of the crystal lattice with the adjacent particle is small, it becomes amorphous on the X-ray diffraction even if the C axis is oriented perpendicular to the film surface. In some cases. In such a case, the vertical alignment of the C-axis film surface can be confirmed by observing the fine structure with a transmission electron microscope (TEM) or the like.

An ordered alloy containing at least one element of Fe and Co and at least one element of Pt and Pd and having magnetic crystal grains having such an L1 ₀ structure is used for magnetic recording of a perpendicular magnetic recording medium. When used as a layer, it is desirable that the C axis of crystal grains be oriented in a direction perpendicular to the substrate. When a metal or alloy thin film is directly formed on an amorphous substrate such as glass or an amorphous film such as SiO ₂ , generally it is often preferentially oriented so that the close-packed surface of the crystal is parallel to the substrate. . Close-packed plane of L1 ₀ type ordered alloy crystals since it is (111) plane, is also generally these ordered alloys tend to be oriented (111). However, the inventors have provided a base layer having a base film containing an amorphous alloy containing Ni on a substrate, on which at least one element of Fe and Co, and of Pt and Pd It contains at least one element, and when the magnetic crystal grains forming a magnetic recording layer having such a L1 ₀ structure, the resulting magnetic recording layer, the magnetic crystal grains is good (001) orientation It has been found that the ordered alloy film has As a result, the perpendicular magnetic recording medium having such a nominal magnetic recording layer has good recording / reproducing characteristics, good SNR characteristics and thermal stability, and high-density recording is possible.

  The term “amorphous” as used herein does not necessarily mean only a completely amorphous material such as glass, but may include a state in which fine crystals having a particle diameter of 2 nm or less are randomly oriented locally.

  As the nonmagnetic substrate used in the present invention, for example, a glass substrate, an Al-based alloy substrate, a Si single crystal substrate having a surface oxidized, a ceramic substrate, a plastic substrate, or the like can be used. Furthermore, those having a surface plated with NiP alloy or the like can be suitably used.

  In the present invention, as a method for forming the underlayer and the magnetic recording layer, for example, a vacuum deposition method, a sputtering method, a chemical vapor deposition method, and a laser ablation method can be used. As the sputtering method, a unitary sputtering method using a composite target, a multi-component simultaneous sputtering method using a plurality of targets of each element, and the like can be suitably used. By heating the substrate temperature to 200 to 500 ° C. before and during the formation of the underlayer and the magnetic recording layer, the ordering of the magnetic recording layer may easily proceed.

  As the perpendicular magnetic recording layer, a multilayer body in which two or more magnetic recording layers having different characteristics are laminated can be used. One or more nonmagnetic layers can be provided as an intermediate layer between two or more magnetic recording layers.

  FIG. 3 is a sectional view showing the structure of another example of the perpendicular magnetic recording medium of the present invention.

  As shown in the figure, this perpendicular magnetic recording medium 20 includes a second magnetic layer 3 in which the magnetic recording layer 3 is formed, for example, via a first magnetic layer 3-1 and a nonmagnetic layer 4 thereon. 1 has the same structure as the perpendicular magnetic recording medium shown in FIG.

  In this case, at least one of exchange coupling interaction and magnetostatic coupling interaction can act between the laminated magnetic recording layers. Such a configuration of the magnetic recording layer can be appropriately selected depending on the magnetic characteristics and manufacturing process required by the magnetic recording / reproducing system.

The preferred composition ratio of the magnetic metal element and the noble metal element in the perpendicular magnetic recording layer is such that the Pt composition is in the range of 35 to 65 at% in the case of Fe—Pt binary alloy, and the Pd composition in the case of Fe—Pd binary alloy. Is in the range of 40 to 63 at%, and in the case of Co—Pt binary alloy, the Pt composition is in the range of 40 to 70%. If the composition ratio of each alloy within this range, it is possible to form an L1 ₀ ordered phase. In the perpendicular magnetic recording layer, an element such as Cu, Zn, Zr, or C, or a compound such as MgO or SiO ₂ can be added in an appropriate amount for the purpose of improving magnetic characteristics or electromagnetic conversion characteristics. In particular, addition of Cu is preferable in that it has an effect of promoting the ordering of the ordered alloy.

  The thickness of the perpendicular magnetic recording layer is determined by the required value of the magnetic recording / reproducing system, but is preferably 0.5 to 50 nm. More preferably, it is 0.5 to 20 nm. If it is thinner than 0.5 nm, it tends to be difficult to form a continuous film.

  In the present invention, the underlayer is provided to reinforce the function of the magnetic recording layer as a magnetic recording medium. Specifically, it is a thin film inserted between the magnetic recording layer and the substrate, and can be composed of a single layer or a multilayer film.

  As the amorphous alloy containing Ni, for example, an alloy system such as Ni—Nb, Ni—Ta, Ni—Zr, Ni—W, Ni—Mo, and Ni—V alloy is preferably used.

  The Ni content in these alloys is preferably 20 to 70 at%. If it is less than 20 at% or more than 70 at%, it tends to be difficult to become amorphous. More preferably, it is 30 to 50 at%, and if it is within this range, the C-axis orientation of the ordered alloy crystal particles tends to be further improved.

  Further, it is possible to insert one or more crystalline base films made of a Cr alloy or an alloy containing Cr as a main component between the base film containing an amorphous alloy containing Ni and the magnetic recording layer. it can. This can further improve the C-axis orientation of the magnetic recording layer.

  FIG. 4 is a sectional view showing the configuration of another example of the perpendicular magnetic recording medium of the present invention.

  As shown in the figure, this perpendicular magnetic recording medium 30 includes a crystalline base film 5 made of a Cr alloy or an alloy containing Cr as a main component, further provided between the base film 2 and the magnetic recording layer 3. Other than this, the configuration is the same as that of the perpendicular magnetic recording medium shown in FIG. At this time, the base layer 15 is a laminate of the base film 2 and the base film 5.

  As a crystalline base film made of such a Cr alloy or an alloy containing Cr as a main component, for example, an alloy system such as Cr alone, Cr—Ti and Cr—Ru can be preferably used.

  When these alloys are used, the Cr content in the alloy is preferably 60 at% or more, more preferably 60 to 95 at%, still more preferably 70 to 85 at%. If it is less than 60 at%, the C-axis orientation tends to be difficult to improve.

  Further, a crystal made of at least one element or alloy selected from the group consisting of Pt, Pd, Ag, Cu, and Ir between the base film made of an alloy containing Cr as a main component and the magnetic recording layer. It is possible to insert at least one layer of a functional underlayer. As a result, the C-axis orientation of the magnetic recording layer can be further improved, and in addition to this effect, there is an effect of promoting the ordering of the ordered alloy of the magnetic recording layer. Energy can be increased to increase thermal fluctuation resistance.

  FIG. 5 is a cross-sectional view showing the configuration of another example of the perpendicular magnetic recording medium of the present invention.

  As shown in the figure, the perpendicular magnetic recording medium 40 is made of at least one element or alloy selected from the group consisting of Pt, Pd, Ag, Cu, and Ir between the magnetic recording layer 3 and the undercoat film 5. 4 has the same configuration as that of the perpendicular magnetic recording medium shown in FIG. 4 except that a crystalline base film 6 is further provided. At this time, the base layer 15 is a laminate of the base film 2, the base film 5, and the base film 6.

  The crystalline base film made of at least one element or alloy selected from the group consisting of Pt, Pd, Ag, Cu, and Ir preferably has an average crystal grain size of 3 nm to 10 nm. Therefore, a good SNR can be obtained. If the average particle size exceeds 10 nm, the magnetic separation between the magnetic recording layer crystal particles becomes insufficient, and the SNR tends to decrease. If the average particle size is less than 3 nm, the crystal particle size of the magnetic recording layer is small. The thermal fluctuation resistance tends to decrease.

  By exposing the surface of the base film containing an amorphous alloy to oxygen, oxygen can be introduced into the surface of the base film. Thereby, the C-axis orientation of the magnetic recording layer can be improved and the average crystal grain size of the magnetic recording layer can be reduced.

  As a method for exposing the surface of the base film containing an amorphous alloy to oxygen, a small amount of oxygen gas is introduced into the film formation chamber after the base film is formed, and the resulting base layer surface is brought into an oxygen atmosphere for a short time. The method of exposure can be used. In addition, a method of exposing to an ozone atmosphere, a method of irradiating the surface of the underlayer with oxygen radicals or oxygen ions, and the like can be used. These methods are preferable from the viewpoint of productivity because it is not necessary to take out the substrate formed from the film formation chamber into the atmosphere and leave it for a long time during the medium film formation.

  The perpendicular magnetic recording medium of the present invention can be used as a so-called perpendicular double-layer medium by providing a soft magnetic backing layer between a substrate and an underlayer.

  FIG. 6 is a cross-sectional view showing the configuration of another example of the perpendicular magnetic recording medium of the present invention.

  As shown in the figure, this perpendicular magnetic recording medium 50 has the same configuration as that of the perpendicular magnetic recording medium shown in FIG. 1 except that a soft magnetic backing layer 7 is provided between the substrate 1 and the base film 2.

  The high magnetic permeability soft magnetic underlayer has the function of a magnetic head that circulates a recording magnetic field from a magnetic head for magnetizing a perpendicular magnetic recording layer, for example, a single pole head, to the magnetic head side in the horizontal direction. It plays a part, and can play the role of improving the recording and reproducing efficiency by applying a steep and sufficient perpendicular magnetic field to the recording layer of the magnetic field.

  Examples of such a soft magnetic backing layer include CoZrNb, FeSiAl, FeTaC, CoTaC, NiFe, Fe, FeCoB, FeCoN, and FeTaN.

  Further, a bias applying layer such as an in-plane hard magnetic film and an antiferromagnetic film can be provided between the soft magnetic backing layer and the substrate. The soft magnetic underlayer easily forms a magnetic domain, and spike-like noise is generated from this magnetic domain. Therefore, by providing a bias applying layer to which a magnetic field is applied in one radial direction, a soft magnetic underlayer is provided. A magnetic field can be prevented from being generated by applying a bias magnetic field to the magnetic backing layer.

  FIG. 7 is a cross-sectional view showing the configuration of another example of the magnetic recording medium of the present invention.

  As shown in the figure, this perpendicular magnetic recording medium 60 has the same configuration as the perpendicular magnetic recording medium shown in FIG. 6 except that a bias applying layer 8 is further provided between the substrate 1 and the soft magnetic underlayer 7. .

  The bias applying layer can have a single layer structure or a stacked structure of two or more layers (not shown). When a laminated structure is used, anisotropy can be finely dispersed, so that it is difficult to form a large magnetic domain.

  Examples of the biasing layer material include CoCrPt, CoCrPtB, CoCrPtTa, CoCrPtTaNd, CoSm, CoPt, CoPtO, CoPtCrO, CoPt-SiO2, CoCrPt-SiO2, CoCrPtO-SiO2, IrMn, PtMn, and FeMn.

  A protective layer can be further provided on the magnetic recording layer. Examples of the protective layer include C, diamond-like carbon (DLC), SiNx, SiOx, and CNx.

  FIG. 8 is a partially exploded perspective view showing an example of the magnetic recording / reproducing apparatus of the present invention.

  A rigid magnetic disk 121 for recording information according to the present invention is mounted on a spindle 122 and is driven to rotate at a constant rotational speed by a spindle motor (not shown). A slider 123 equipped with a recording head for accessing and recording information on the magnetic disk 121 and an MR head for reproducing information is attached to the tip of a suspension 124 made of a thin plate spring. The suspension 124 is connected to one end side of an arm 125 having a bobbin portion for holding a drive coil (not shown).

  On the other end side of the arm 125, a voice coil motor 126, which is a kind of linear motor, is provided. The voice coil motor 126 is composed of a drive coil (not shown) wound around the bobbin portion of the arm 125, and a magnetic circuit composed of a permanent magnet and a counter yoke arranged so as to sandwich the coil.

  The arm 125 is held by ball bearings (not shown) provided at two locations above and below the fixed shaft 127, and is driven to rotate and swing by a voice coil motor 126. That is, the position of the slider 123 on the magnetic disk 121 is controlled by the voice coil motor 126. In the figure, reference numeral 128 denotes a lid.

  EXAMPLES Hereinafter, an Example is shown and this invention is demonstrated more concretely.

Example 1
A 2.5-inch hard disk-shaped nonmagnetic glass substrate (TS-CZ manufactured by OHARA) was prepared, and the substrate was introduced into a vacuum chamber of an ANELVA C-3010 type sputtering apparatus.

After evacuating the vacuum chamber of the sputtering apparatus to 1 × 10 ⁻⁶ Pa or less, a Co-5% Zr-5% Nb target is used and a Co-5% Zr-5% Nb alloy is used as a soft magnetic backing layer. A 100 nm film was formed.

  Furthermore, a Ni—Ta alloy film having a thickness of 10 nm was formed as a first underlayer.

  Next, the substrate surface was heated to 300 ° C. using an infrared lamp heater, and then 5 nm of Cr was formed as a second underlayer.

  Subsequently, a 5 nm thick Fe-45 at% Pt-5 at% Cu alloy was formed as a magnetic recording layer.

  On top of that, 5 nm of C was deposited as a protective layer.

  After forming the protective layer, the substrate was taken out from the vacuum chamber, and a perfluoropolyether (PFPE) lubricant was applied to the protective layer surface by a dipping method to a thickness of 13 angstroms to obtain magnetic recording media.

  For the film formation of Co-5% Zr-5% Nb, Cr, Fe-45% Pt-5% Cu, and C, Fe-45% Pt-5% Cu and C targets were used, respectively, and DC sputtering was used. The film was formed by this method, and the input power to each target was fixed at 500 W.

  In addition, the Ni—Ta alloy film is formed by using a binary co-sputtering method using a Ni target and a Ta target, and adjusting the input power to each target, thereby reducing the Ta content in the Ni—Ta alloy to 0. , 10, 20, 30, 40, 50, 60, 70, 80, 90, 100% to obtain magnetic recording media using Ni-Ta alloys of various compositions as the first underlayer.

  The sputtering Ar gas pressure at the time of forming each layer was 0.7 Pa for Co-5% Zr-5% Nb, Ni-Ta, Cr, and C, and 8 Pa for Fe-45% Pt-5% Cu.

  Further, instead of the Ni—Ta alloy as the first base film, Ni—Nb, Ni—Zr, Ni-40W, Ni—V, Ni—Mo, and Ni—Hf are used as alloys of Ni and various metals. Magnetic recording media each formed with an alloy were prepared in the same manner.

  A sectional view showing an example of the obtained magnetic recording medium is shown in FIG.

  As shown in the figure, this perpendicular magnetic recording medium is formed on a substrate 21 with a soft magnetic layer 22, a base layer 27 including a first base film 23 and a second base film 24, a magnetic recording layer 25, and a protective layer 26. Are sequentially stacked.

Each magnetic recording medium was evaluated for recording / reproducing (R / W) characteristics using a spin stand. In the measurement of recording / reproducing (R / W) characteristics, a combination of a single pole head having a recording track width of 0.3 μm and an MR head having a reproducing track width of 0.2 μm was used as the magnetic head. The measurement was performed by rotating the disk at 4200 rpm at a constant position of 20 mm in radius position.
As the medium SNR, the signal-to-noise ratio (SNRm) (where S is the output of the linear recording density of 119 kfci and Nm is the rms (root mean square) value at 716 kfci) was obtained for the reproduced wave after passing through the differentiation circuit. For a magnetic recording medium using Ni—Ta alloys having various compositions as the first underlayer, the medium SNR value is plotted against the Ta content, and the obtained graph is shown in FIG. In addition, among the examples in which alloys of Ni and various metals are formed as the first base film, Ni-40at% Ta alloy, Ni-40at% Nb alloy, Ni-40at% Zr alloy, Ni-40at% W alloy Table 1 below shows the obtained media SNR values for magnetic recording media using Ni-40 at% V alloy, Ni-40 at% Mo alloy, and Ni-40 at% Hf alloy.

  Further, as an index of recording resolution, the half-value width dPW50 of the reproduced wave after passing through the differentiating circuit was examined. Table 1 below shows the full width at half maximum dPW50 for magnetic recording media using various alloys as the first underlayer.

  For each magnetic recording medium, using a Philips X-ray diffractometer X'pert Pro, Cu-Kα rays were generated under the conditions of an acceleration voltage of 45 kV and a filament current of 40 mA, and the θ-2θ method and ω-rocking curve were used. The crystal structure and crystal plane orientation were evaluated. Table 1 below shows the values of the half-value width Δθ50 obtained from the ω-rocking curve of the FePtCu (001) peak for the magnetic recording media each using various alloys as the first underlayer.

  Further, for each magnetic recording medium, the average crystal grain size of each layer was examined by planar TEM observation of each layer. As a result, both the Co-5% Zr-5% Nb layer and the first underlayer were amorphous. On the other hand, the Cr layer and the magnetic recording layer were found to be composed of crystal grains having particle sizes in the range of 10 to 20 nm and 7 to 15 nm, respectively.

(Comparative Example 1)
As a comparative example, a magnetic recording medium using MgO as a conventional underlayer was produced as follows.

  A 2.5-inch hard disk-shaped nonmagnetic glass substrate (TS-CZ manufactured by OHARA) was prepared, and the substrate was introduced into a vacuum chamber of an ANELVA C-3010 type sputtering apparatus.

After evacuating the vacuum chamber of the sputtering apparatus to 1 × 10 ⁻⁶ Pa or less, a Co-5% Zr-5% Nb alloy is formed to a thickness of 100 nm as a soft magnetic backing layer, and MgO is further formed as a first underlayer. A 10 nm film was formed.

  Next, after heating the substrate surface to 300 ° C. using an infrared lamp heater, Cr is 5 nm as the second underlayer, Fe-45 at% Pt-5 at% Cu alloy is 5 nm as the magnetic recording layer, and C as the protective layer. Were sequentially deposited at 5 nm.

  After the film formation, the substrate was taken out from the vacuum chamber, and a PFPE lubricant was applied to the protective layer surface by a dip method to a thickness of 13 angstroms to obtain a magnetic recording medium of Comparative Example 1.

  Co-5% Zr-5% Nb, MgO, Cr, Fe-45% Pt-5% Cu, and C are formed by depositing Co-5% Zr-5% Nb, MgO, Cr, Fe-45, respectively. Using a% Pt-5% Cu, C target, Co-5% Zr-5% Nb, Cr, Fe-45% Pt-5% Cu, C is formed by DC sputtering, and MgO is formed by RF sputtering. The input power to each target was fixed at 500W.

  The sputtering Ar gas pressure at the time of forming each layer was 0.7 Pa for Co-5% Zr-5% Nb, MgO, Cr, and C, and 8 Pa for Fe-45% Pt-5% Cu.

  The recording / reproduction characteristics of the obtained magnetic recording medium were measured in the same manner as in Example 1. Similarly, the half-value width Δθ50 obtained from the SNR, dPW50 and FePtCu (001) peak ω-rocking curves were as follows: Table 1 shows.

As shown in Table 1, as an underlying layer of the magnetic recording layer including crystal grains having an L1 ₀ structure comprising a Fe-45at% Pt-5at% Cu alloy from 5nm, Ni-40at% Ta, Ni-40at% Nb, Ni-40at% Zr, Ni-40at% W, Ni-40at% V, Ni-40at% Mo, and Ni-40at% Hf alloys such as Ni-40at% Hf alloy, and under the Cr crystalline alloy When the base layer made of the base film is formed, the half-value width Δθ50 of the magnetic recording layer is significantly lower than that of the base layer made of the MgO base film and the Cr crystalline alloy base film. It was found that the SNR and dPW50 were also significantly improved.

  Further, as shown in FIG. 10, it was found that the SNR was significantly improved when the Ni composition was in the range of 20 to 70 at%, and the SNR was further improved in the range of 30 to 50 at%. Further, it was found that the SNR was remarkably improved by alloying with Ni as compared with the first base film of Ta simple substance. The same tendency was observed when Ni—Nb, Ni—Zr, Ni—W, Ni—V, Ni—Mo, and Ni—Hf alloys were used.

  As a result of XRD measurement by the θ-2θ method, it was confirmed that the magnetic recording layer of Example 1 was generally C-axis oriented. In the magnetic recording layer of Comparative Example 1, the value of the half-value width Δθ50 is relatively large, and the magnetic recording layer of Example 1 has significantly improved C-axis orientation as compared with the magnetic recording layer of Comparative Example 1. I found out.

(Example 2)
A 2.5-inch hard disk-shaped nonmagnetic glass substrate was prepared, introduced into a sputtering apparatus, and the vacuum chamber of the sputtering apparatus was evacuated to 1 × 10 ⁻⁶ Pa or less, and then Co-5% Zr-5% Nb. A soft magnetic backing layer was formed, and then a Ni-40% Ta alloy film was formed as the first underlayer by the same method as in Example 1.

  Subsequently, the substrate surface is heated to 300 ° C. using an infrared lamp heater, and a Cr—Ti alloy base film is formed as a second base film to a thickness of 5 nm, followed by magnetic recording layer formation, protective layer formation, and lubrication. The magnetic agent was applied in the same manner as in Example 1 to obtain a magnetic recording medium. The formation of the Cr—Ti alloy underlayer uses a binary simultaneous sputtering method using a Cr target and a Ti target, and the Ti content is changed in the same manner as in Example 1 by adjusting the input power to each target. I let you. In addition, a medium using a Cr—Ru alloy instead of the Cr—Ti alloy underlayer was produced by the same method.

  About the obtained magnetic recording medium, it carried out similarly to Example 1, and evaluated R / W characteristic, crystal structure, and crystal plane orientation.

  FIGS. 11 and 12 show the relationship between the Ti composition and the SNR in the second underlayer made of the Cr-containing alloy, and the relationship between the Ru composition and the SNR, respectively. From these figures, it was found that when Ti or Ru was added in the range of 5 to 40%, the improvement of SNR was more remarkable and better than Example 1 using Cr as the second underlayer. .

Example 3
A 2.5-inch hard disk-shaped nonmagnetic glass substrate was prepared, introduced into a sputtering apparatus, and the vacuum chamber of the sputtering apparatus was evacuated to 1 × 10 ⁻⁶ Pa or less, and then Co-5% Zr-5 A% -40 Nb soft magnetic backing layer and a Ni-40% Ta alloy film as the first underlayer were formed in the same manner as in Example 1. Thereafter, the substrate was heated in the same manner as in Example 1 to form a Cr base film as the second base film.

  Subsequently, the substrate was heated in the same manner to form a Pt base film having a thickness of 10 nm as a third base film. For the Pt underlayer, a Pt target was used and the input power was set to 500 W by DC sputtering. The sputtering Ar gas pressure at the time of forming the Pt underlayer was 8 Pa.

  Further, after the magnetic recording layer and the protective layer were formed in the same manner as in Example 1, a lubricant was applied on the protective layer to obtain a magnetic recording medium.

  Further, the combination of the first base film, the second base film, and the third base film is changed to the combinations shown in the following Tables 2-1 to 2-3, and the magnetic recording medium is similarly configured. Obtained.

  The first undercoat is Ni-40at% Ta alloy, Ni-40at% Nb alloy, Ni-40at% Zr alloy, Ni-40at% W alloy, Ni-40at% V alloy, Ni-40at% Mo alloy, and Ni-40at% Hf alloy is selected, and the second underlayer is selected from Cr, Cr-25% Ta alloy, Cr-25% Ti alloy, and Cr-25% Ru alloy, and the third underlayer is used. Is selected from Pt, Pd, Ir, Ag, and Cu, or without the third underlayer.

  A sectional view showing an example of the obtained magnetic recording medium is shown in FIG.

  As shown in the figure, this perpendicular magnetic recording medium has a soft magnetic layer 62, a base film 68 composed of a first base film 63, a second base film 64, and a third base film 65 on a substrate 61, The magnetic recording layer 66 and the protective layer 67 are sequentially stacked.

  For each medium, the RW characteristics were examined, and the SNR value was determined in the same manner as in Example 1.

  The obtained results are shown in Tables 2-1 to 2-3 below.

上記表２−１ないし表２−３から、第３の下地膜として、さらにＰｔ、Ｐｄ、Ｉｒ、Ａｇ、及びＣｕから選択される結晶性の下地膜を挿入すると、下地層が第１の下地膜及び第２の下地膜の積層からなる磁気記録媒体よりも、さらに、ＳＮＲが向上することが分かった。

From Tables 2-1 to 2-3 above, when a crystalline base film selected from Pt, Pd, Ir, Ag, and Cu is further inserted as the third base film, the base layer becomes lower than the first base film. It was found that the SNR was further improved as compared with the magnetic recording medium composed of the lamination of the ground film and the second base film.

In addition, when the values of the half-value width dPW50 of the reproduced wave after passing through the differentiation circuit and the half-value width Δθ50 obtained from the ω-rocking curve of the FePtCu (001) peak were examined in the same manner as in Example 1, When a crystalline base film selected from Pt, Pd, Ir, Ag, and Cu is further inserted as the base film 3, the base layer is formed by stacking the first base film and the second base film. It was found that the recording resolution in the C-axis orientation and RW characteristics of the magnetic recording layer was further improved as compared with the medium.
Further, when examined by planar TEM observation of each layer in the same manner as in Example 1, the Co-5% Zr-5% Nb layer and the first underlayer were both amorphous, whereas the second It was found that the underlayer, the third underlayer, and the magnetic recording layer each consisted of crystal grains having average grain sizes in the range of 10 to 20 nm, 3 to 10 nm, and 3 to 10 nm.

Example 4
A 2.5-inch hard disk-shaped nonmagnetic glass substrate was prepared, introduced into a sputtering apparatus, and the vacuum chamber of the sputtering apparatus was evacuated to 2 × 10 ⁻⁶ Pa or less, and then Co-5% Zr-5% Nb Soft magnetic underlayer deposition, Ni-40% Ta alloy seed layer deposition, and substrate surface heating were performed in the same manner as in Example 1. Subsequently, Ar-1% O ₂ gas is introduced into the vacuum chamber so that the pressure in the chamber becomes 5 × 10 ⁻² Pa, and the surface of the Ni-40% Ta seed layer is formed in this Ar / O ₂ atmosphere. Exposure for 5 seconds. Subsequently, Cr underlayer film formation, Pt underlayer film formation, magnetic recording layer film formation, protective layer film formation, and lubricant application were sequentially performed in the same manner as in Example 3.

  Similarly to Example 3, the combination of the first base film, the second base film, and the third base film was changed, and a magnetic recording medium was obtained in the same manner.

  For each medium, the RW characteristics were examined, and the SNR value was determined in the same manner as in Example 1.

  Of the obtained results, the results when the first base film is a Ni-40 at% Ta alloy, a Ni-40 at% Nb alloy, or a Ni-40 at% Zr alloy are shown in Table 3 as an example.

  As is apparent from Table 3, when the surface of the first base film is exposed to an oxygen atmosphere, the SNR is higher than the value obtained when the surface of the first base film obtained in Example 2 is not exposed to the oxygen atmosphere. Improved. In addition, as a result of AES depth direction analysis, it was found that an oxygen deposition layer exists at the interface between the seed layer and the underlayer of each medium subjected to the exposure treatment in the oxygen atmosphere.

Similar results were obtained when Ni-40at% V alloy, Ni-40at% Mo alloy, and Ni-40at% Hf alloy were used as the first base film. When the values of the half-value width dPW50 of the regenerated wave after passing through the differential circuit and the half-value width Δθ50 obtained from the ω-rocking curve of the FePtCu (001) peak were examined, the surface of the first underlayer was in an oxygen atmosphere. When exposed to the inside, the recording resolution in the C-axis orientation and RW characteristics of the magnetic recording layer can be further improved as compared with the value in which the surface of the first underlayer obtained in Example 2 is not exposed to the oxygen atmosphere. I understood.
Further, when examined by planar TEM observation of each layer in the same manner as in Example 1, the Co-5% Zr-5% Nb layer and the first underlayer were both amorphous, whereas the second The underlayer, the third underlayer, and the magnetic recording layer were found to be composed of crystal grains having an average particle size in the range of 10 to 15 nm, 3 to 7 nm, and 3 to 7 nm, respectively.

Sectional drawing showing the structure of an example of the perpendicular magnetic recording medium based on this invention The figure for demonstrating the L1 ₀ structure of the magnetic-recording layer used for this invention Sectional drawing showing the structure of another example of the perpendicular magnetic recording medium based on this invention Sectional drawing showing the structure of another example of the perpendicular magnetic recording medium based on this invention Sectional drawing showing the structure of another example of the perpendicular magnetic recording medium based on this invention Sectional drawing showing the structure of another example of the perpendicular magnetic recording medium based on this invention Sectional drawing showing the structure of another example of the perpendicular magnetic recording medium based on this invention Sectional drawing showing the structure of an example of the magnetic recording / reproducing apparatus based on this invention Sectional drawing showing the structure of an example of the perpendicular magnetic recording medium based on this invention Graph showing the relationship between the Ta content in the first Ni—Ta alloy underlayer and the medium SNR Graph showing the relationship between Ti content and SNR in the second Cr—Ti alloy underlayer Graph showing the relationship between the Ru content in the second Cr—Ru alloy underlayer and the SNR Sectional drawing showing the structure of an example of the perpendicular magnetic recording medium based on this invention

Explanation of symbols

  1, 2, 61 ... substrate, 2, 23, 63 ... first undercoat film, 3, 25, 66 ... perpendicular magnetic recording layer, 26, 67 ... protective layer, 4 ... nonmagnetic layer, 5, 24, 64 ... Second under film, 6, 65... Third under film, 15, 27, 68... Under layer 10, 20, 30, 40, 50, 60... Perpendicular magnetic recording medium, 7, 22, 62. Backing layer, 8 ... Bias applying layer, 121 ... Magnetic disk, 122 ... Spindle, 123 ... Slider, 124 ... Suspension, 125 ... Arm, 126 ... Voice coil motor, 127 ... Fixed shaft

Claims (12)

A substrate,
An underlayer having a first underlayer formed on the substrate and including an amorphous alloy containing Ni;
Is formed on the underlayer contains at least one element of at least one element, and Pt and Pd of Fe and Co, having an L1 ₀ structure, magnetic containing predominantly (001) -oriented magnetic crystal grains A perpendicular magnetic recording medium comprising a recording layer.   The amorphous alloy is selected from the group consisting of a Ni-Nb alloy, a Ni-Ta alloy, a Ni-Zr alloy, a Ni-W alloy, a Ni-Mo alloy, and a Ni-V alloy. Item 2. The perpendicular magnetic recording medium according to Item 1.   3. The perpendicular magnetic recording medium according to claim 1, wherein the amorphous alloy has a Ni content of 20 to 70 at%.   The base layer includes a first base film containing the amorphous alloy and a crystalline second containing a Cr simple substance or an alloy containing Cr provided on the first base film containing the amorphous alloy. 4. The perpendicular magnetic recording medium according to claim 1, wherein the perpendicular magnetic recording medium is laminated with an undercoat film.   The perpendicular magnetic recording medium according to claim 1, wherein the alloy containing Cr is a Cr—Ti alloy or a Cr—Ru alloy.   The Ti content when the Cr-containing alloy is a Cr-Ti alloy, or the Ru content when the Cr-Ru alloy is a Cr-Ru alloy is 5 to 40 at%. Perpendicular magnetic recording medium.   A crystalline third underlayer containing at least one element selected from the group consisting of Pt, Pd, Ag, Cu, and Ir is provided between the second crystalline underlayer and the magnetic recording layer. The perpendicular magnetic recording medium according to claim 4, further comprising a ground film.   8. The perpendicular magnetic recording medium according to claim 1, wherein the third underlayer includes crystal grains having an average particle diameter of 3 nm to 10 nm.   9. The perpendicular magnetic recording medium according to claim 1, wherein one surface of the first underlayer is exposed to oxygen.   10. The perpendicular magnetic recording medium according to claim 1, further comprising a soft magnetic backing layer between the first undercoat film and the substrate.   A magnetic recording / reproducing apparatus comprising the perpendicular magnetic recording medium according to claim 1 and a recording / reproducing head.   The magnetic recording / reproducing apparatus according to claim 11, wherein the recording / reproducing head is a single magnetic pole.

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