JP2016030857A - Sputtering target for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target for a magnetic recording medium that enables a recording film which has a lower Pt content and higher density than before and also has high Ku and a high order parameter to be manufactured.SOLUTION: A sputtering target for a magnetic recording medium according to the present invention is a sintered body which contains one or both of at least Ir and Pd in a magnetic alloy containing Fe and Pt as metal dissolved in the magnetic alloy, and further contains carbon and one or both of metal oxide or silicon oxide as oxide. The magnetic alloy has a composition such that Pt is contained by 35-45 at.%, one or both of Ir and Pd is contained by 4-10 at.% in total, and Fe and inevitable impurities are contained for the rest, relative density of the sintered body being 90% or higher.SELECTED DRAWING: None

Description

  The present invention relates to a material for a recording layer in a high-density magnetic recording medium, and more particularly to a sputtering target for forming a magnetic recording film applied to a perpendicular magnetic recording medium.

  Due to the rapid increase in the amount of information in recent years, the amount of data stored worldwide is expected to reach 8 billion Tbytes in 2020. As these large-capacity data recording media, HDDs with a low recording bit unit price are often used. Considering the influence of cost and environment, it is necessary to increase the amount of information to be stored without greatly increasing the number of HDDs. For this purpose, it is important to increase the recording density per medium mounted on the HDD.

As a technique for improving the recording density, a heat-assisted recording method has been attracting attention in which writing is performed by irradiating a near-field light onto a magnetic recording medium to locally heat the surface to reduce the coercivity of the recording layer. When this heat assist method is used, even if the coercive force of the recording layer is several tens of kOe, writing can be performed by the recording magnetic field of the current head. For this reason, in the heat-assisted magnetic recording system, it is possible to use a material having a high magnetic anisotropy (Ku) on the order of 10 ⁶ J / m ³ (10 ⁷ erg / cc) for the recording layer, and thermal stability. While maintaining the above, the crystal grain size of the recording layer can be reduced to 6 nm or less. Such are known FePt or CoPt having an L1 ₀ type ordered structure as a high material Ku is obtained, Ku value is high in bulk (about ^{7 × 10 7 erg / cc)} FePt studied extensively in Has been done.

FePt also exist disordered phase called type A1 not only L1 ₀ type ordered phase. It is known that an irregular phase which is a high-temperature phase is easily formed in a vapor phase quenching method such as a sputtering method generally used in the production of a medium. is necessary. As a measure for reducing the ordering temperature, a method of adding a third element to FePt is disclosed (for example, see Non-Patent Documents 1 and 2). Non-Patent Document 1 describes Cu, Ag, and Au as the third element. Non-Patent Document 2 describes Cu as the third element. On the other hand, an attempt to reduce the ordering temperature without adding a third element has been reported (see, for example, Patent Document 1). In Patent Document 1, an FePt film is formed on an MgO single crystal substrate, and the Pt composition is 48 at. % To 81 at. It is reported that a high Ku such as 1.8 × 10 ⁷ erg / cc and 2.7 × 10 ⁷ erg / cc can be obtained at a production temperature of 300 ° C.

Further, in order to improve the recording density, the recording medium needs to have a granular structure in which the magnetic crystal grains are magnetically separated. For this reason, various additives have been studied in order to obtain a granular structure. C or SiO ₂ has been studied as an additive for obtaining a granular structure (see, for example, Non-Patent Document 3). As a method for producing an FePt-C target, a method of producing and mixing various alloy powders by an atomizing method is disclosed (for example, see Patent Document 2).

  Regarding a sputtering target made of a sintered body of an alloy made of FePt or an alloy containing an additive component in an FePt alloy, the Pt content is 20 to 70 atomic%, and by reducing the amount of gas components in the sintered target, A technique for lowering the annealing temperature necessary for ordering the PtFe alloy film is disclosed (for example, see Patent Document 3). Further, as a technique for reducing the amount of gas components in the sputtering target, Pt is set to 30 to 60 at. A technique of melting twice when forming a casting ingot for a sputtering target made of a PtFe-based alloy containing% is disclosed (for example, see Patent Document 4).

JP 2004-311925 A JP 2012-178210 A JP 2003-313659 A JP 2006-161082 A

J. et al. Appl. Phys. 92, p. 6104-6109 (2002) Appl. Phys. Letters 102, 132406 (2013) Magnetics Society of Japan, 177th meeting, p. 31-37 (2011)

As in Non-Patent Documents 1 and 2, the method of adding a third element such as Cu, Ag, or Au is effective in reducing the ordering temperature, but as described in Non-Patent Document 2, Ku is used. Cause a decline. In Patent Document 1, since the third element is not added, high Ku can be maintained at a low ordering temperature. However, an expensive single crystal substrate is used, and the Pt content is 48 at. % Or more is necessary, so the effect of reducing the amount of Pt used is small, and there is a problem in terms of cost. In Non-Patent Document 3, it is reported that the degree of order of FePt is reduced by adding either C or SiO ₂ to FePt. Further, Non-Patent Document 3 reports that C is more likely to lower the c-axis orientation of FePt than SiO ₂ but is less likely to lower the order of FePt. Further, in Non-Patent Document 3, it is reported that SiO ₂ is more likely to lower the order of FePt than C, but has an effect of increasing the c-axis orientation of FePt. As described above, the additive material for obtaining the granular structure has advantages and disadvantages depending on the material.

  Regarding the target fabrication method, when the additive for obtaining the granular structure is only carbon and the melting point difference between the metal species as the alloy components is small (for example, Pt (melting point 1768 ° C.) and Fe (melting point 1538 ° C.) When the difference in melting point is less than 1000 ° C. as in the case of an alloy, it is effective to use atomized powder. However, it is general that the upper limit of the spraying temperature of the atomizing apparatus is about 2000 ° C., and when adding a metal element having a melting point exceeding 1800 ° C. as an alloy component, it becomes difficult to produce atomized powder. Moreover, when a target is produced using atomized powder, the effect of reducing the oxygen content of the target is expected. However, when an oxide is added to the target, the oxygen reduction effect by the atomized powder is weakened by the oxygen derived from the oxide. At the same time, since the atomized powder is a sphere, it is difficult to produce a target that is difficult to diffuse and has a high relative density. Also, when the melting point of the metal species as the alloy component is large (for example, when the difference in melting point is 1000 ° C. or more), the composition on the low melting point side may evaporate first when the atomized powder is produced. is there. Furthermore, since the atomized powder is a sphere, it is difficult to produce a target that is difficult to diffuse and has a high relative density.

  In Patent Document 3, in order to reduce the gas component amount of the sintering target, it is necessary to use a powder having a small gas component amount as a metal powder for sintering, or to perform a degassing process during sintering. Moreover, it is necessary to melt | dissolve patent document 4 twice. For this reason, both techniques have problems in terms of productivity and cost.

  An object of the present invention is to provide a sputtering target for a magnetic recording medium that can produce a recording film having a lower Pt content, higher density, higher Ku, and higher order than conventional.

  As a result of diligent investigations to solve the above-mentioned problems, the inventors have substituted Pt into the composition of the recording layer based on FePt and added either or both of Ir and Pd to contain Pt. By reducing the amount and containing C as the granular material and either or both of the metal oxide and silicon oxide as the oxide, a recording film having a high density, a high Ku and a degree of order is produced. The inventors have found a sputtering target that can be used to complete the present invention. That is, the sputtering target for a magnetic recording medium according to the present invention contains at least one or both of Ir and Pd as a metal that dissolves in the magnetic alloy in the magnetic alloy containing Fe and Pt, and further contains carbon, And a sintered body containing one or both of a metal oxide and silicon oxide as an oxide, and the magnetic alloy contains Pt of 35 to 45 at. %, Ir or Pd or both in total 4 to 10 at. %, The balance being Fe and inevitable impurities, and the relative density of the sintered body is 90% or more.

  The sputtering target for a magnetic recording medium according to the present invention further contains at least one of Ag, Au, and Cu as a metal that dissolves in the magnetic alloy, and the magnetic alloy includes Fe, Pt, and Ir. Or one or both of Pd in a total of 85 to 95 at. %, And at least any one of Ag, Au, and Cu is 5 to 15 at. It is preferable to have a composition containing%. A high Ku and a high degree of order can be achieved at the same time.

In the sputtering target for magnetic recording media according to the present invention, the metal oxide is preferably at least one of Cr ₂ O ₃ , Ta ₂ O ₅ and TiO ₂ . A granular structure can be formed more reliably.

  In the sputtering target for a magnetic recording medium according to the present invention, the sintered body is preferably formed by a discharge plasma sintering method. The relative density can be further increased. Moreover, productivity can be improved and cost can be reduced.

  In the sputtering target for a magnetic recording medium according to the present invention, it is preferable that the sintered body is formed under conditions of a sintering end temperature of 1050 to 1300 ° C. The relative density can be further increased. In addition, the generation of particles during film formation can be suppressed.

  The present invention can provide a sputtering target for a magnetic recording medium that can produce a recording film having a lower Pt content, higher density, higher Ku, and higher degree of order.

  Next, although an embodiment is shown and explained in detail about the present invention, the present invention is limited to these descriptions and is not interpreted. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

  The sputtering target for a magnetic recording medium according to the present embodiment contains at least one or both of Ir and Pd as a metal that dissolves in the magnetic alloy in the magnetic alloy containing Fe and Pt, and further contains carbon, and It is a sintered body containing one or both of a metal oxide and silicon oxide as an oxide, and the magnetic alloy contains Pt of 35 to 45 at. % (Atomic%, atomic%), one or both of Ir and Pd in total 4 to 10 at. %, With the balance being Fe and inevitable impurities, and the relative density of the sintered body is 90% or more.

The magnetic alloy is a solid solution containing Fe, Pt, and one or both of Ir and Pd. Ir and Pd are added in place of a part of Pt in the composition of the magnetic alloy containing Fe and Pt, and have a role of reducing the Pt content. It is presumed that Ir and Pd are substituted with Pt sites. Ir and Pd both have a role of maintaining perpendicular magnetic anisotropy. In the present embodiment, Fe and, and Pt, the content of either one or both of Ir or Pd, by the respective specific ranges, in the formed thin film using a sputtering target, L1 ₀ ordered structure Can be formed.

The magnetic alloy has a Pt of 35 to 45 at. %contains. More preferably, Pt is 36 to 40 at. %contains. The Pt content is 35 at. If it is less than%, is preferable in view of cost reduction, the thin film formed using the sputtering target, the formation of L1 ₀ ordered structure is difficult. The Pt content is 45 at. If it exceeds%, it is desirable from the viewpoint of ordering, but it is a composition containing a large amount of expensive Pt, which is not desirable from the viewpoint of cost.

The magnetic alloy has a total of 4 to 10 at. %contains. More preferably, Ir and Pd are 4.5 to 10 at. %contains. The total content of Ir and Pd is 5 at. If it is less than%, it is desirable from the viewpoint of maintaining a high Ku value, but the amount of reducing the Pt content is small, and the cost reduction effect is small. The total content of Ir and Pd is 10 at. Beyond percent, in the formed thin film using a sputtering target, it is difficult to form the L1 ₀ ordered structure, Ku is deteriorated.

  The solid solution state and composition of the magnetic alloy can be determined by, for example, inductively coupled plasma atomic emission spectrometry (ICP-AES Inductively Coupled Plasma Atomic Emission Spectrometry) or XRF X-Ray Fluorescence elemental analysis. I can confirm. As the measurement method, an optimal method is selected according to the element and concentration contained in the target.

  The sputtering target for a magnetic recording medium according to the present embodiment further contains at least one of Ag, Au, and Cu as a metal that dissolves in the magnetic alloy, and the magnetic alloy includes Fe, Pt, Ir, or Ir. A total of 85 to 95 at. %, And at least any one of Ag, Au, and Cu is 5 to 15 at. It is preferable to have a composition containing%. The ordering temperature can be reduced by adding Ag, Au and Cu. The reason why Ag, Au, or Cu reduces the ordering temperature is not clear, but since all of Ag, Au, and Cu have a melting point of about 1000 ° C., the addition of these metal elements has an appropriate phase transition temperature. As a result, the ordering temperature is estimated to be reduced. In addition, since Cu is dissolved in Fe, Cu is replaced with Fe sites, and the free energy of the magnetic alloy is increased. As a result, it is presumed that the order temperature is reduced. The total content of Ag, Au and Cu is 5 at. If it is less than%, the effect of reducing the ordering temperature may not be obtained. The total content of Ag, Au and Cu is 15 at. If it exceeds%, the effect of reducing the ordering temperature is great, but the Ku value may be reduced. It is preferable that Ag, Au, and Cu are all dissolved in the magnetic alloy. The combined content of Ag, Au and Cu is 5 to 15 at. %, Ag, Au, or Cu is stably dissolved without being precipitated at the grain boundaries.

  The magnetic alloy contains Pt, one or both of Ir and Pd, and at least one of Ag, Au, and Cu blended as necessary at the predetermined content described above. The balance has a composition composed of Fe and inevitable impurities. Here, the inevitable impurities are elements contained in the raw material or elements inevitably mixed in the manufacturing process, and are, for example, P, S, N, O, Cd, and Zn. The content of inevitable impurities in the magnetic alloy is not particularly limited as long as it does not impair the effects of the present invention. % Or less, preferably 0.01 at. % Or less is more preferable. Moreover, in this embodiment, you may add other elements other than Fe, Pt, Ir, Pd, Ag, Au, and Cu to a magnetic alloy in the range which does not impair the effect of this invention. Other elements are, for example, B, Si, or Ru.

  Examples of combinations of magnetic alloys include Fe—Pt—Ir, Fe—Pt—Pd, Fe—Pt—Ir—Pd, Fe—Pt—Ir—Ag, Fe—Pt—Pd—Ag, and Fe—Pt—Ir—. Pd—Ag, Fe—Pt—Ir—Au, Fe—Pt—Pd—Au, Fe—Pt—Ir—Pd—Au, Fe—Pt—Ir—Cu, Fe—Pt—Pd—Cu, Fe—Pt— Ir-Pd-Cu, Fe-Pt-Ir-Ag-Au, Fe-Pt-Pd-Ag-Au, Fe-Pt-Ir-Pd-Ag-Au, Fe-Pt-Ir-Ag-Cu, Fe- Pt-Pd-Ag-Cu, Fe-Pt-Ir-Pd-Ag-Cu, Fe-Pt-Ir-Au-Cu, Fe-Pt-Pd-Au-Cu, Fe-Pt-Ir-Pd-Au- Cu, Fe-Pt-Ir-Ag-Au-Cu, Fe-Pt-Pd-A -Au-Cu, an Fe-Pt-Ir-Pd-Ag-Au-Cu. These combinations are merely examples, and the present invention is not limited to these.

  Carbon and oxide are present around the particles made of the magnetic alloy in the thin film formed using the sputtering target, and have a role of magnetically separating the particles made of the magnetic alloy. When only one of carbon and oxide is added, it is difficult to achieve both the degree of order and other characteristics (for example, c-axis orientation and separability). Here, the separability means a property of magnetically separating particles made of a magnetic alloy in a granular structure. In this embodiment, by adding both carbon and oxide, the balance between the degree of order and other characteristics can be improved by the interaction of carbon and oxide. The reason why the balance between the degree of order and other characteristics can be improved by adding both carbon and oxide is not clear, but the effect of optimizing the driving force of phase separation and the coexistence of carbon and oxide. It is presumed that the oxide solid solution in the FePt particles is suppressed.

  Carbon may exist as carbon particles in the sputtering target or may form an alloy with Fe. In this embodiment, it is preferable to exist as carbon particles, and it is more preferable that the carbon particles exist around particles made of a magnetic alloy. The content of carbon is preferably 20 to 50 mol%, and more preferably 25 to 45 mol%.

The oxide is preferably present as oxide particles in the sputtering target, and more preferably the oxide particles are present around particles made of a magnetic alloy. The oxide is a metal oxide or silicon oxide. In this embodiment, it is more preferable to contain silicon oxide as an oxide. A granular structure can be formed more reliably. Moreover, in this embodiment, it is preferable to contain a metal oxide as an oxide. The metal oxide is preferably at least one of chromium oxide, tantalum oxide, and titanium oxide. A granular structure can be formed more reliably. Only one oxide may be used, or two or more oxides may be used in combination. The chromium oxide is, for example, Cr ₂ O ₃ . The tantalum oxide is Ta ₂ O ₅ , for example. Titanium oxide is, for example, TiO _2. In the oxide, part of oxygen may be reduced by C, and the crystal structure of the oxide may have oxygen vacancies. Part of oxygen in the oxide is reduced by C, whereby the oxygen content of the sputtering target is reduced, and as a result, a higher-density sputtering target can be obtained. The oxide content is preferably 1 to 18 mol%, more preferably 2 to 16 mol%.

  The sputtering target for a magnetic recording medium according to the present embodiment preferably has a composition containing 20 to 50 mol% carbon, 1 to 18 mol% oxide, and the balance being a magnetic alloy, and 25 to 45 mol% carbon. It is more preferable to have a composition containing 2 to 16 mol% of an oxide and the balance being a magnetic alloy. Further, the oxide content (oxide content / C content) with respect to the C content is preferably 0.02 to 0.2 in terms of molar ratio, and 0.04 to 0.15. More preferably. By setting it as this range, the effect which improves the balance of a regularity and another characteristic can be heightened more.

  The relative density of the sintered body is 90% or more. More preferably, it is 98% or more. If the relative density is less than 90%, many particles are generated during film formation. The relative density is a value expressed as a percentage by dividing the measured value of the density of the sintered body by the theoretical value and then multiplying by 100. The measured value of the density of the sintered body can be a specific gravity measured by, for example, the Archimedes method.

  Target production methods are roughly classified into a melting method and a sintering method. Although the dissolution method is very effective for producing a high-purity material, it is difficult to uniformly dissolve the metal and the oxide having different melting points as in this embodiment. For this reason, it is desirable to use a sintering method for producing a multi-element alloy.

  An example of the manufacturing method of the sputtering target for magnetic recording media which concerns on this embodiment is demonstrated. First, the mixing process which mixes the powder used as a sintering raw material, and obtains mixed powder is performed. Next, a pelletizing process for pressing the mixed powder into a lump and a sintering process for sintering the mixed powder of the sintering raw material are performed. Finally, the sintered body obtained in the sintering process is processed into a desired size to obtain a sputtering target.

(Mixing process)
The powder used as the raw material for sintering is not particularly limited, and commercially available metal powder, oxide powder, and carbon powder can be used depending on the composition to be produced. The carbon powder is, for example, graphite powder or carbon black powder. Moreover, you may use the alloy powder produced by the gas atomization method. The particle size of the powder is an item that is optimized depending on the combination of materials or alloys used. For example, it is preferable to use a powder having an average particle size in the range of 5 to 100 μm determined by a laser diffraction scattering method. More preferably, a powder in the range of 5 to 50 μm is used. The powder mixing method is not particularly limited, and any of general mixing methods such as a planetary ball mill, a ball mill, and a V-type mixer can be used.

(Pelletization process)
In the pelletizing process, a binder may be added in addition to the mixed powder.

(Sintering process)
The method for producing the sintered body is, for example, hot pressing (HP), discharge plasma sintering (SPS), or hot isostatic pressing (HIP). In these sintering methods, since sintering is performed under pressure, a pelletizing step performed prior to the sintering step may be omitted. The sintering method has advantages and disadvantages, but it is preferable to use a spark plasma sintering method (SPS) that can complete the sintering in a short time from the viewpoint of productivity and cost. By forming the sintered body by the discharge plasma sintering method, the relative density can be set to 90% or more, for example.

  In the discharge plasma sintering method, a mixed powder of sintering raw material is filled in a discharge plasma sintering die such as a carbon die, and a pulsed direct current is applied to the mixed powder and the die while pressing from above and below to generate a discharge. Sintering is performed using the heat generated by the plasma. The current is appropriately controlled according to a desired temperature increase speed. The temperature raising speed is preferably 800 to 1050 ° C./hr, and more preferably 900 to 1050 ° C./hr. The sintering process is preferably performed in a vacuum. Here, the vacuum means a state where the pressure is lower than the standard atmospheric pressure, for example, 15 Pa or less.

  In this embodiment, when the sintering method is a discharge plasma sintering method, a primary pressurizing step of heating while applying pressure from above and below, and a pressurizing force of the primary pressurizing step after the primary pressurizing step. It is preferable to perform a secondary pressurizing step of heating while pressurizing with a high applied pressure. A denser sintered body can be obtained by performing the primary pressurizing step and the secondary pressurizing step. The pressure at the time of sintering is optimized depending on the required target size and alloy composition, and is not particularly limited, but the applied pressure in the primary pressurizing step is preferably 10 to 40 MPa, and preferably 20 to 35 MPa. More preferred. The applied pressure in the secondary pressurization is preferably 80 MPa or less, more preferably 50 to 75 MPa, exceeding the applied pressure in the primary pressurization.

  In the sputtering target for a magnetic recording medium according to the present embodiment, the sintered body is preferably formed under the condition of the sintering end temperature of 1050 to 1300 ° C. The sintering end temperature is more preferably 1100 to 1300 ° C. In the present specification, the sintering end temperature refers to a temperature at which the current is turned off, for example, a measured value of the die temperature when the current is turned off. When the sintering end temperature is less than 1050 ° C., the relative density becomes low (for example, less than 90%), which may cause generation of particles during film formation. Further, when the sintering end temperature exceeds 1300 ° C., the magnetic alloy may be dissolved during sintering when it contains a metal species having a relatively low melting point such as Ag, Au or Cu.

(Processing process)
In the processing step, the processing method of the sintered body is not particularly limited, and examples thereof include general machining such as cutting, grinding, electric discharge, laser processing, water jet processing, and polishing.

The sputtering target for a magnetic recording medium according to this embodiment is preferably used for forming a thin film by sputtering on a substrate heated to 300 to 500 ° C. The temperature of the substrate is more preferably 300 to 480 ° C, and particularly preferably 300 to 400 ° C. Temperature of the substrate during film formation by sputtering is even 300 to 500 ° C. can form ordered thin films having an L1 ₀ structure. The thin film formed at a substrate temperature of 300 to 500 ° C. using the sputtering target for magnetic recording media according to this embodiment preferably has a Ku of 1.00 × 10 ⁷ erg / cc or more, and 1.50. It is more preferable that it is × 10 ⁷ erg / cc or more.

Thin film formed by deposition by a sputtering method using a sputtering target for a magnetic recording medium according to the present embodiment, particles made of a magnetic alloy having an L1 ₀ structure, any metal oxide or silicon oxide as the carbon and oxide It has a granular structure surrounded by one or both.

  The thin film formed by the sputtering method using the sputtering target for magnetic recording media according to this embodiment has an easy axis of magnetization in the vertical direction.

A thin film formed by sputtering using the sputtering target for magnetic recording media according to this embodiment has a high degree of order. The degree of order (degree of ordering) is measured by measuring the out of plane using XRD (X-ray differential), and the ratio of the L1 ₀ phase regular line (001) integral intensity to the basic line (002) integral intensity (hereinafter referred to as the “out of plane”). , (001) / (002) intensity ratio). The thin film formed at a substrate temperature of 300 to 500 ° C. using the sputtering target for magnetic recording media according to this embodiment preferably has a (001) / (002) strength ratio of 1.400 or more. More preferably, it is 450 or more.

  A thin film formed by sputtering using the sputtering target for magnetic recording media according to this embodiment has high c-axis orientation. The c-axis orientation was determined from the FePt (111) integrated intensity by measuring the out of plane using XRD (X-ray diffraction). A thin film formed at a substrate temperature of 300 to 500 ° C. using the sputtering target for a magnetic recording medium according to this embodiment preferably has an FePt (111) integrated intensity of 0 (not detected).

  The thin film formed by sputtering using the magnetic recording medium sputtering target according to this embodiment can be suitably used for the recording layer of the magnetic recording medium.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited to the examples.

Example 1
First, a sputtering target for a magnetic recording medium having a composition of 73 mol% (Fe ₅₀ Pt ₄₀ Pd ₁₀ ) -25 mol% C-2 mol% SiO ₂ was prepared as follows. Here, regarding Fe ₅₀ Pt ₄₀ Pd ₁₀ , Fe, Pt, and Pd indicate elements constituting the magnetic alloy, and subscripts (numbers) attached to the right of each element are at. %. Henceforth, an alloy is described with the same rule. In the composition of the sputtering target for a magnetic recording medium, mol% of the magnetic alloy is a value obtained by subtracting 100 mol% of C and mol% of oxide, and is shown in Table 1. Hereinafter, the description of “mol%” of the magnetic alloy is omitted. First, the mass of each powder of Fe, Pt, Pd, C, and SiO ₂ was measured so as to obtain a desired composition. Next, the powder was premixed for 15 min or more. This pre-mixed powder and φ10 mm ZrO ₂ balls were filled in a pod for a planetary ball mill and sealed with Ar gas. Thereafter, mixing was performed at 200 rpm for 3 hours. Next, the mixed powder was filled in a carbon die for spark plasma sintering and pre-pressed. Next, it was installed in a vacuum chamber, and vacuum deaeration was performed so that the inside of the vacuum chamber became 15 Pa. After vacuum degassing, the initial pressure was adjusted to 30 MPa (primary pressurization step), and the current value was adjusted to increase the temperature at a speed of 900 ° C./hr. Then, secondary pressurization was performed at a pressure of 60 MPa (secondary pressurization step), and sintering was completed at 1150 ° C. The sintered body was processed into a desired size and thickness to obtain a sputtering target for a magnetic recording medium.

  Next, a sputtering target for a magnetic recording medium was attached to a sputtering apparatus, and an evaluation sample having the following layer structure with respect to a substrate temperature of 500 ° C. was prepared as a sample for evaluating magnetic characteristics and crystallinity.

An adhesion layer made of Ni ₆₀ Ta ₄₀ and having a thickness of 20 nm was formed on a glass substrate by a sputtering method at a pressure of 0.6 Pa. Next, an alignment control layer made of Cr ₈₀ Mn ₂₀ and having a thickness of 20 nm was formed by a sputtering method at a pressure of 0.6 Pa. Next, a 5 nm-thick underlayer made of MgO was formed at a pressure of 3 Pa by sputtering. Thereafter, heating was performed with a heater. Next, after waiting until the substrate temperature reaches 500 ° C., (Fe ₅₀ Pt ₄₀ Pd ₁₀ ) −25 mol% C−2 mol% SiO ₂ recording layer 10 nm is 6 Pa by sputtering using a sputtering target for magnetic recording medium. A protective layer made of carbon was subsequently formed with a film thickness of 7 nm by sputtering, and used as an evaluation sample at a substrate temperature of 500 ° C. (Example 1a).

  An evaluation sample was prepared in the same manner as in Example 1a, except that the waiting time before forming the recording layer was adjusted and the substrate temperature was changed to 300 ° C. (Example 1b).

(Example 2)
The composition of the sputtering target for the magnetic recording medium was (Fe ₅₅ Pt ₄₀ Ir ₅ ) -25 mol% C-2 mol% SiO ₂ and the sintering end temperature was 1250 ° C. A sputtering target was produced. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Example 2a) at a substrate temperature of 500 ° C. or an evaluation sample (Example 2b) at a temperature of 300 ° C. was produced in the same manner as in Example 1.

(Example 3)
The composition of the sputtering target for the magnetic recording medium was (Fe _49.5 Pt ₃₆ Ir _4.5 Ag ₁₀ ) -25 mol% C-2 mol% SiO ₂ and the sintering end temperature was 1200 ° C. Similarly, a sputtering target for a magnetic recording medium was produced. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Example 3a) at a substrate temperature of 500 ° C. or an evaluation sample (Example 3b) at 300 ° C. was produced in the same manner as in Example 1.

Example 4
Except that the composition of the sputtering target for magnetic recording medium was (Fe _49.5 Pt ₃₆ Ir _4.5 Ag ₁₀ ) -23 mol% C-2 mol% Cr ₂ O ₃ and the sintering end temperature was 1200 ° C. As in Example 1, a sputtering target for a magnetic recording medium was produced. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Example 4a) at a substrate temperature of 500 ° C. or an evaluation sample (Example 4b) at a temperature of 300 ° C. was produced in the same manner as in Example 1.

(Example 5)
Except that the composition of the sputtering target for magnetic recording medium was (Fe _49.5 Pt ₃₆ Ir _4.5 Ag ₁₀ ) -23 mol% C-1 mol% Ta ₂ O ₅ and the sintering end temperature was 1200 ° C. As in Example 1, a sputtering target for a magnetic recording medium was produced. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Example 5a) at a substrate temperature of 500 ° C. or an evaluation sample (Example 5b) at 300 ° C. was produced in the same manner as in Example 1.

(Example 6)
A sputtering target for a magnetic recording medium was prepared in the same manner as in Example 1 except that the sintering end temperature was 1100 ° C. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Example 6a) at a substrate temperature of 500 ° C. or an evaluation sample (Example 6b) at a temperature of 300 ° C. was produced in the same manner as in Example 1.

(Comparative Example 1)
A sputtering target for a magnetic recording medium was produced in the same manner as in Example 1 except that the composition of the sputtering target for the magnetic recording medium was (Fe ₅₀ Pt ₅₀ ) −25 mol% C−2 mol% SiO ₂ . Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Comparative Example 1a) at a substrate temperature of 500 ° C. or an evaluation sample (Comparative Example 1b) at a temperature of 300 ° C. was produced in the same manner as in Example 1.

(Comparative Example 2)
A sputtering target for a magnetic recording medium was produced in the same manner as in Example 1 except that the composition of the sputtering target for a magnetic recording medium was (Fe ₆₀ Pt ₄₀ ) -25 mol% C-2 mol% SiO ₂ . Using the obtained sputtering target for magnetic recording medium, an evaluation sample (Comparative Example 2a) at a substrate temperature of 500 ° C. or an evaluation sample (Comparative Example 2b) at a temperature of 300 ° C. was prepared in the same manner as in Example 1.

(Comparative Example 3)
The magnetic layer was formed in the same manner as in Example 1 except that the recording layer target composition of the sputtering target for magnetic recording medium was (Fe ₅₅ Pt ₃₀ Ir ₁₅ ) -25 mol% C-2 mol% SiO ₂ and the sintering end temperature was 1280 ° C. A sputtering target for a recording medium was produced. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Comparative Example 3a) at a substrate temperature of 500 ° C. or an evaluation sample (Comparative Example 3b) at a temperature of 300 ° C. was prepared in the same manner as in Example 1.

(Comparative Example 4)
The composition of the sputtering target for the magnetic recording medium was (Fe _41.25 Pt ₃₀ Ir _3.75 Cu ₂₅ ) -25 mol% C-2 mol% SiO ₂ and the sintering end temperature was 1050 ° C. Similarly, a sputtering target for a magnetic recording medium was produced. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Comparative Example 4a) at a substrate temperature of 500 ° C. or an evaluation sample (Comparative Example 4b) at a temperature of 300 ° C. was prepared in the same manner as in Example 1.

(Comparative Example 5)
A sputtering target for a magnetic recording medium was prepared in the same manner as in Example 1 except that the composition of the sputtering target for the magnetic recording medium was (Fe ₅₀ Pt ₄₀ Pd ₁₀ ) −40 mol% C and the sintering end temperature was 1150 ° C. . Using the obtained sputtering target for magnetic recording media, an evaluation sample (Comparative Example 5a) at a substrate temperature of 500 ° C. or an evaluation sample (Comparative Example 5b) at a substrate temperature of 500 ° C. was prepared in the same manner as in Example 1.

(Comparative Example 6)
A sputtering target for a magnetic recording medium was produced in the same manner as in Example 1 except that the sintering end temperature was 950 ° C. Using the obtained sputtering target for a magnetic recording medium, an evaluation sample (Comparative Example 6a) at a substrate temperature of 500 ° C. or an evaluation sample (Comparative Example 6b) at a temperature of 300 ° C. was produced in the same manner as in Example 1.

(Relative density)
The relative density was calculated | required by measuring the specific gravity by the Archimedes method regarding the sputtering target for magnetic recording media produced by the Example and the comparative example, and remove | excluding the theoretical value. The theoretical value of the target density is calculated by the following method. First, at. % In wt. Converted to% (mass%). Here, at. % Represents at. Of each metal component in the magnetic alloy when the component is each metal component of the magnetic alloy. % Is a value obtained by multiplying mol% of the magnetic alloy in the target, and when the component is an oxide or C, it is a value of mol% of the oxide or C in the target. The obtained wt. From%, the volume is determined as follows. The wt. % Is divided by the specific gravity of each component to determine the volume of each component. Finally, the theoretical value of the target density is obtained by dividing 100 by the total volume of each component. The theoretical density value calculated by this method is regarded as the theoretical density value of the target.

(Magnetic properties and crystallinity)
With respect to the evaluation samples prepared for evaluating the magnetic characteristics and crystallinity, the magnetic characteristics and crystallinity of the recording layer were evaluated. The recording layer was measured for perpendicular and in-plane MH loops using a magnetic property measuring apparatus (MPMS3 (Magnetic Property Measurement System 3), manufactured by Quantum Design), and Ku (anisotropic energy) was evaluated. The degree of ordering was determined by measuring the out of plane using XRD (X-ray diffraction), and the ratio of the L1 ₀ phase regular line (001) integral intensity to the basic line (002) integral intensity ((001) / ( 002) Strength ratio) was used as an index. Further, the c-axis orientation was measured by measuring out of plane using XRD, and the FePt (111) integrated intensity was used as an index. The relative density, magnetic properties, (001) / (002) intensity ratio, and FePt (111) integrated intensity measurement results are summarized in Table 1.

  As shown in Table 1, the Pt concentration was 40 at. % And Ir or Pd added as the third element in the optimum range, and the Pt concentration was 50 at. %, And in comparison with Comparative Example 1 in which the third element was not added, Example 1 and Example 3 were Ku values and (001) / (002) strengths in the evaluation samples at the substrate temperature of 500 ° C. Although the ratio was inferior to that of Comparative Example 1, the evaluation sample with a substrate temperature of 300 ° C. had characteristics equivalent to or higher than those of Comparative Example 1.

  The Pt concentration is 36 at. When Example 3 in which Ir as the third element and Ag as the fourth element were added in the optimum ranges was compared with Comparative Example 1, Example 3 was evaluated at a substrate temperature of 500 ° C. In the sample, the Ku value and the (001) / (002) intensity ratio were inferior to those in Comparative Example 1, but the evaluation sample at the substrate temperature of 300 ° C. obtained characteristics equal to or higher than those in Comparative Example 1.

Examples 4 and 5 are examples in which the type of oxide added to Example 3 was changed. In both Examples 4 and 5, the Ku and (001) / (002) strength ratios were the same as in Example 3. In particular, the composition of (Fe _49.5 Pt ₃₆ Ir _4.5 Ag ₁₀ ) -23 mol% C-2 mol% Cr ₂ O ₃ shown in Example 4 has a Pt concentration of 40 at. Even if it was less than%, a high Ku value and a (001) / (002) intensity ratio were shown.

  Example 6 is an example in which the sintering end temperature was lowered from 1150 ° C. to 1100 ° C. with respect to Example 1. Example 6 was 90% or more, and the Ku value and the (001) / (002) intensity ratio were the same as Example 1. In addition, Example 1 has a higher relative density than Example 6, and it was confirmed that the relative density can be further increased by setting the sintering end temperature to 1150 ° C. or higher.

  In Comparative Example 1, the Pt content was 50 at. %, Which is not preferable in terms of cost.

  Comparative Example 2 has a Pt concentration of 40 at. % Is an example. As shown in Table 1, the Pt concentration is the same at 40 at. %, In Example 1, the easy axis of magnetization was in the vertical direction, whereas in Comparative Example 2, the easy axis of magnetization was in the in-plane direction. From this result, it is considered that Pd or Ir has an effect of maintaining the perpendicular magnetic anisotropy.

  Comparative Example 3 has an Ir concentration of 5 at. % To 15 at. It is an example of increasing to%. In Comparative Example 3, the Ku value was significantly reduced. This is probably because Ir weakens the magnetic moment of Fe compared to Pt, so Ms (saturation magnetization) decreases and Ku also decreases.

  Comparative Example 4 is an example in which the fourth element was excessively added to Example 2. In Comparative Example 4, the Ku value was deteriorated as compared with Example 2. This is considered to be due to a decrease in Ms as in Comparative Example 3.

Comparative Example 5 is an example in which no SiO ₂ is added to Example 1. In Comparative Example 5, the FePt (111) peak was confirmed, and the c-axis orientation was deteriorated. From this result, it is considered that the addition of SiO ₂ has an effect of improving the c-axis orientation.

  Comparative Example 6 is an example in which the sintering end temperature is lower than that of Example 1. In Comparative Example 6, the relative density was lower than that of Example 1 and lower than 90%. As a result, it is considered undesirable from the viewpoint of particles.

  It was confirmed that the sputtering target of each example can form a thin film having high regularity even when the substrate temperature is 300 ° C.

In the present invention, one or both of Ir and Pd and, if necessary, at least one of Ag, Au and Cu are added to FePt in an optimal composition, and C and SiO _{2 are} used as granular materials. A sputtering target to which an oxide such as Cr ₂ O ₃ , Ta ₂ O ₅ , or TiO ₂ is added is formed by, for example, a discharge plasma sintering method, thereby suppressing Ku value deterioration and reducing the amount of Pt. Can be produced. Therefore, the present invention is promising in that it can be applied to perpendicular magnetic recording, which is expected to have a higher recording density.

Claims (5)

A magnetic alloy containing Fe and Pt contains at least one or both of Ir and Pd as a metal that dissolves in the magnetic alloy, and further, carbon and any one of metal oxide and silicon oxide as an oxide. A sintered body containing one or both,
The magnetic alloy has Pt of 35 to 45 at. %, Ir or Pd or both in total 4 to 10 at. Containing, and having the balance as Fe and inevitable impurities,
A sputtering target for a magnetic recording medium, wherein the sintered body has a relative density of 90% or more. Furthermore, at least any one of Ag, Au, and Cu is contained as a metal that dissolves in the magnetic alloy,
The magnetic alloy contains Fe, Pt, and one or both of Ir and Pd in a total of 85 to 95 at. %, And at least any one of Ag, Au, and Cu is 5 to 15 at. The sputtering target for a magnetic recording medium according to claim 1, wherein the sputtering target has a composition containing 1%.   The sputtering target for a magnetic recording medium according to claim 1, wherein the metal oxide is at least one of chromium oxide, tantalum oxide, and titanium oxide.   The sputtering target for a magnetic recording medium according to claim 1, wherein the sintered body is formed by a discharge plasma sintering method.   The sputtering target for a magnetic recording medium according to any one of claims 1 to 4, wherein the sintered body is formed under a condition of a sintering end temperature of 1050 to 1300 ° C.