Sputtering target for magnetic recording medium

Abstract

A sputtering target for a magnetic recording medium, comprises: a metal phase containing Pt and at least one or more selected from Mn and V, with the balance being Co and incidental impurities; and an oxide phase containing at least B and O.

Description

Sputtering targets for magnetic recording media

[0001] The present invention relates to a sputtering target for a magnetic recording medium, and more particularly to a sputtering target containing Co, Pt, and an oxide.

[0002] In the magnetic disk of a hard disk drive, information signals are recorded in minute bits on the magnetic recording medium. To further improve the recording density of magnetic recording media, it is necessary to reduce the size of the bit that holds one piece of recorded information while also increasing the signal-to-noise ratio, which is an index of information quality. In order to increase the signal-to-noise ratio, it is essential to increase the signal or reduce the noise.

[0003] Currently, magnetic thin films with a granular structure of CoPt-based alloy-oxide are used as magnetic recording media for recording information signals (see, for example, Non-Patent Document 1). This granular structure consists of columnar CoPt-based alloy crystal grains and the oxide crystal grain boundaries surrounding them.

[0004] To increase the recording density of such magnetic recording media, it is necessary to smooth the transition regions between recording bits to reduce noise, and to smooth the transition regions between recording bits, it is essential to refine the CoPt-based alloy crystal grains contained in the magnetic thin film.

[0005] On the other hand, as the magnetic crystal grains become smaller, the strength of the recording signal that each magnetic crystal grain can hold decreases. To achieve both the miniaturization of magnetic crystal grains and the strength of the recording signal, it is necessary to reduce the center-to-center distance between the crystal grains.

[0006] On the other hand, as the grain size of the CoPt-based alloy in the magnetic recording medium becomes smaller, the thermal stability of the recorded signal is impaired due to the superparamagnetic phenomenon, resulting in the loss of the recorded signal, a phenomenon known as thermal fluctuation. This thermal fluctuation phenomenon is a major obstacle to achieving higher recording densities in magnetic disks.

[0007] To overcome this obstacle, it is necessary to increase the magnetic energy of each CoPt-based alloy crystal grain so that the magnetic energy overcomes the thermal energy. The magnetic energy of each CoPt-based alloy crystal grain is determined by the product v × Ku of the volume v of the CoPt-based alloy crystal grain and the magnetocrystalline anisotropy constant Ku. Therefore, in order to increase the magnetic energy of the CoPt-based alloy crystal grain, it is essential to increase the magnetocrystalline anisotropy constant Ku of the CoPt-based alloy crystal grain (see, for example, Non-Patent Document 2).

[0008] Furthermore, in order to grow CoPt-based alloy crystal grains with a large Ku in a columnar shape, it is essential to achieve phase separation between the CoPt-based alloy crystal grains and the grain boundary material. If the phase separation between the CoPt-based alloy crystal grains and the grain boundary material is insufficient and the intergranular interaction between the CoPt-based alloy crystal grains becomes large, the coercive force Hc of the magnetic thin film consisting of a CoPt-based alloy-oxide granular structure will decrease, thermal stability will be impaired, and thermal fluctuations will become more likely to occur. Therefore, it is also important to reduce the intergranular interaction between the CoPt-based alloy crystal grains.

[0009] It is possible that the miniaturization of magnetic crystal grains and the reduction of the center-to-center distance between magnetic crystal grains can be achieved by miniaturizing the crystal grains in the Ru underlayer (an underlayer provided for controlling the orientation of the magnetic recording medium).

[0010] However, it is difficult to refine the crystal grains in the Ru underlayer while maintaining the crystal orientation (see, for example, Non-Patent Document 3). As a result, the size of the crystal grains in the Ru underlayer of current magnetic recording media remains almost the same as when longitudinal magnetic recording media were replaced by perpendicular magnetic recording media, at approximately 7 nm to 8 nm.

[0011] On the other hand, from the viewpoint of improving the magnetic recording layer rather than the Ru underlayer, studies have been conducted to advance the refinement of magnetic crystal grains. Specifically, studies have been conducted to refine the magnetic crystal grains by increasing the amount of oxide added to the CoPt-based alloy-oxide magnetic thin film and reducing the volume ratio of magnetic crystal grains (see, for example, Non-Patent Document 4). This method achieved refinement of the magnetic crystal grains. However, this method does not allow for a reduction in the center-to-center distance of the magnetic crystal grains because the width of the crystal grain boundary increases with the increase in the amount of oxide added.

[0012] Furthermore, the addition of a second oxide to the single oxide used in conventional CoPt-based alloy-oxide magnetic thin films has been investigated (see, for example, Non-Patent Document 5). However, when adding multiple oxide materials, guidelines for selecting the materials have not been clearly defined, and even now, investigations are continuing into oxides to be used as grain boundary materials for CoPt-based alloy crystal grains. The present inventors have investigated the inclusion of oxides with low and high melting points (specifically, B with a low melting point of 450°C). ２ O ３ and a high-melting-point oxide having a melting point higher than the melting point of the CoPt alloy (about 1450°C)) is found to be effective, and ２ O ３ and a high-melting-point oxide, and a sputtering target for magnetic recording media containing the oxide (Patent Document 1).

[0013] WO2018 / 083951 publication

[0014] T. Oikawa et al. , IEEE TRANSACTIONS ON MAGNETICS, September 2002, VOL. 38, NO. 5, p. 1976-1978S. N. Piramanayagam, JOURNAL OF APPLIED PHYSICS, 2007, 102, 011301S. N. Piramanayagam et al. , APPLIED PHYSICS LETTERS, 2006, 89, 162504Y. Inaba et al. , IEEE TRANSACTIONS ON MAGNETICS, July 2004, VOL. 40, NO. 4, p. 2486-2488I. Tamai et al. , IEEE TRANSACTIONS ON MAGNETICS, November 2008, VOL. 44, NO. 11, p. 3492-3495

[0015] An object of the present invention is to provide a sputtering target for magnetic recording media that can produce magnetic thin films with improved uniaxial magnetic anisotropy, reduced intergranular exchange coupling, and improved thermal stability and SNR (signal-to-noise ratio) in order to achieve even higher capacity.

[0016] Unlike the control of oxide components employed in Patent Document 1, the inventors have focused on metal components and discovered that by using a sputtering target having an alloy phase containing V or Mn, it is possible to minimize the decrease in the crystalline magnetic anisotropy constant Ku of the magnetic thin film obtained by sputtering and reduce α, thereby realizing an improvement in uniaxial magnetic anisotropy and a reduction in intergranular exchange coupling, and have completed the present invention.

[0017] According to the present invention, there is provided a sputtering target for a magnetic recording medium, which comprises a metal phase containing at least one element selected from Mn and V, Pt, and the balance being Co and unavoidable impurities, and an oxide phase containing at least B and O.

[0018] It is preferable that the sputtering target for a magnetic recording medium contains 1 mol % or more and 30 mol % or less of Pt and 0.5 mol % or more and 10 mol % or less of at least one selected from Mn and V relative to the total of the metal phase components, and that the sputtering target for a magnetic recording medium contains 25 vol % or more and 40 vol % or less of the oxide phase relative to the entire sputtering target for a magnetic recording medium.

[0019] The present invention also provides a sputtering target for a magnetic recording medium, which comprises a metal phase containing at least one element selected from Mn and V, at least one element selected from Cr and Ru, Pt, and the balance being Co and unavoidable impurities, and an oxide phase containing at least B and O.

[0020] It is preferable that the sputtering target for a magnetic recording medium contains, relative to the total of the metal phase components, 1 mol % or more and 30 mol % or less of Pt, 0.5 mol % or more and 10 mol % or less of at least one selected from Mn and V, and more than 0.5 mol % and 30 mol % or less of at least one selected from Cr and Ru, and that the sputtering target for a magnetic recording medium contains 25 vol % or more and 40 vol % or less of the oxide phase relative to the entire sputtering target for a magnetic recording medium.

[0021] The oxide phase containing at least B and O may further contain an oxide of at least one element selected from V, Ru, Ti, Si, Ta, Cr, Al, Nb, Mn, Co, Ni, Zn, Y, Mo, W, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr.

[0022] Furthermore, according to the present invention, there is provided a sputtering target for magnetic recording media, which comprises a metal phase comprising at least one selected from Mn and V, Pt, and the balance being Co and unavoidable impurities, and an oxide phase.

[0023] It is preferable that the sputtering target for a magnetic recording medium contains 1 mol % or more and 30 mol % or less of Pt and 0.5 mol % or more and 10 mol % or less of at least one selected from Mn and V relative to the total of the metal phase components, and that the sputtering target for a magnetic recording medium contains 25 vol % or more and 40 vol % or less of the oxide phase relative to the entire sputtering target for a magnetic recording medium.

[0024] Furthermore, according to the present invention, there is provided a sputtering target for a magnetic recording medium, which comprises a metal phase containing at least one selected from Mn and V, at least one selected from Cr and Ru, Pt, and the balance being Co and unavoidable impurities, and an oxide phase.

[0025] It is preferable that the sputtering target for a magnetic recording medium contains, relative to the total of the metal phase components, 1 mol % or more and 30 mol % or less of Pt, 0.5 mol % or more and 10 mol % or less of at least one selected from Mn and V, and more than 0.5 mol % and 30 mol % or less of at least one selected from Cr and Ru, and that the sputtering target for a magnetic recording medium contains 25 vol % or more and 40 vol % or less of the oxide phase relative to the entire sputtering target for a magnetic recording medium.

[0026] The oxide phase may further contain an oxide of at least one element selected from B, V, Ru, Ti, Si, Ta, Cr, Al, Nb, Mn, Co, Ni, Zn, Y, Mo, W, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr.

[0027] By using the sputtering target for a magnetic recording medium of the present invention, it is possible to produce a high-recording-density magnetic recording medium with improved thermal stability and SNR due to improved uniaxial magnetic anisotropy and reduced intergranular exchange coupling.

[0028] Photographs of a cross section of a sintered body test piece in Example 1 taken with a scanning electron microscope (acceleration voltage 15 keV) (upper: 900x magnification, lower: 3000x magnification). EDS analysis photograph of the lower part (3000x magnification) of Figure 1. Granular medium magnetization curve of Example 1. Photographs of a cross section of a sintered body test piece in Example 2 taken with a scanning electron microscope (acceleration voltage 15 keV) (upper: 900x magnification, lower: 3000x magnification). EDS analysis photograph of the lower part (3000x magnification) of Figure 4. Example 1, XRD profiles in the direction perpendicular to the film surface of the magnetic films of Examples 1, 2 and Comparative Example 1 TEM observation images of the magnetic films (deposited at 16 nm) of Examples 1, 2 and Comparative Example 1 Graph showing the measurement results of Ms of the magnetic films of Examples 1, 2 and Comparative Example 1 Graph showing the measurement results of Hc of the magnetic films of Examples 1, 2 and Comparative Example 1 Graph showing the measurement results of Hn of the magnetic films of Examples 1, 2 and Comparative Example 1 Graph showing α of the magnetic films of Examples 1, 2 and Comparative Example 1 Ku of the magnetic films of Examples 1, 2 and Comparative Example 1 Ｇｒａｉｎ Graph showing the measurement results

[0029] The present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited thereto. In this specification, a sputtering target for a magnetic recording medium may be simply referred to as a sputtering target or a target.

[0030] (1) First Embodiment A sputtering target for a magnetic recording medium according to a first embodiment of the present invention is characterized by comprising a metal phase containing at least one selected from Mn and V, Pt, and the remainder being Co and unavoidable impurities, and an oxide phase containing at least B and O.

[0031] The target of the first embodiment contains 1 mol % to 30 mol % of Pt, 0.5 mol % to 10 mol % of at least one selected from Mn and V, and the remainder of the metal phase is Co and unavoidable impurities. It is preferable that the target for a magnetic recording medium contains 25 vol % to 40 vol % of an oxide phase containing at least B and O relative to the entire sputtering target for a magnetic recording medium.

[0032] The oxide phase containing B and O means a phase containing boron oxide. ２ O３ However, since it is difficult to analyze non-stoichiometric boron oxides themselves, the ICP analysis of boron oxides assumes that the total amount of identified B is B. ２ O ３ In this specification, boron oxide is also referred to as B ２ O ３ It will be explained as follows.

[0033] At least one element selected from Mn and V, Co, and Pt are components of magnetic crystal grains (micromagnets) in the granular structure of the magnetic thin film formed by sputtering. Hereinafter, in this specification, at least one element selected from Mn and V will be abbreviated as "X," and the magnetic crystal grains contained in the magnetic thin film of the magnetic recording medium formed using the target of the first embodiment will also be referred to as "CoPtX alloy crystal grains."

[0034] Co is a ferromagnetic metal element that plays a central role in forming the magnetic crystal grains (micromagnets) of the granular structure of the magnetic thin film. From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPtX alloy crystal grains (magnetic crystal grains) in the magnetic thin film obtained by sputtering and from the viewpoint of maintaining the magnetism of the CoPtX alloy crystal grains (magnetic crystal grains) in the obtained magnetic thin film, the content of Co in the sputtering target according to the first embodiment is preferably 25 mol % or more and 98.5 mol % or less of the total metal components.

[0035] Pt has the function of reducing the magnetic moment of the alloy by alloying with Co and X within a predetermined composition range, and also plays a role in adjusting the magnetic strength of the magnetic crystal grains. From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPtX alloy crystal grains (magnetic crystal grains) in the magnetic thin film obtained by sputtering and from the viewpoint of adjusting the magnetism of the CoPtX alloy crystal grains (magnetic crystal grains) in the obtained magnetic thin film, the content of Pt in the sputtering target according to the first embodiment is preferably 1 mol % or more and 30 mol % or less of the total metal components.

[0036] The present inventors have found that V and Mn have the function of improving the separation of CoPtX alloy crystal grains (magnetic crystal grains) due to the oxide phase in the magnetic thin film, and can reduce intergranular exchange coupling. ２ O ３ A magnetic thin film formed by sputtering using a target (X = V or Mn) and CoPt-B ２ O ３ When compared with a magnetic thin film formed by sputtering using a target, B was found to act as a barrier between adjacent CoPtX alloy crystal grains. ２ O ３ The oxide phase is present deeper in the depth direction (Fig. 7: TEM observation image), and the gradient α at the point where the magnetization curve intersects with the horizontal axis (applied magnetic field) is smaller (Fig. 11), confirming that the separation of the magnetic crystal grains is improved. On the other hand, the magnetocrystalline anisotropy constant Ku per unit grain ｇｒａｉｎ The values ​​are equivalent (FIG. 12), confirming that the uniaxial magnetic anisotropy of the magnetic thin film is good. From the examples described later, it has been found that V reduces α more significantly and Ku less significantly than Mn, and therefore V is more preferable.

[0037] The content of X in the sputtering target according to the first embodiment is preferably 0.5 mol% or more and 10 mol% or less, more preferably 1 mol% or more and less than 10 mol%, and particularly preferably 5 mol% or less, relative to the total metal phase components. Mn and V can be contained alone or in combination as metal phase components of the sputtering target. In particular, the combination of Mn and V is preferable because it can further reduce intergranular exchange coupling and maintain uniaxial magnetic anisotropy.

[0038] The oxide phase becomes a non-magnetic matrix that separates magnetic crystal grains (micro-magnets) in the granular structure of the magnetic thin film. The oxide phase of the sputtering target according to the first embodiment contains at least B and O. Other oxides may include an oxide of at least one element selected from V, Ru, Ti, Si, Ta, Cr, Al, Nb, Mn, Co, Ni, Zn, Y, Mo, W, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr. Specific examples of other oxides include VO ２ , V.O. ３ , V ２ O ５ , RuO ２ , TiO ２ , SiO ２ , Ta ２ O ５ , Cr ２ O ３ , Al ２ O ３ , Nb ２ O ５ , MnO, Mn ３ O ４ , CoO, Co ３ O ４ , NiO, ZnO, Y ２ O ３ , MoO ２ , W.O. ３ , La ２ O ３ , CeO ２ , Nd ２ O ３ , Sm ２ O ３ , Eu ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Lu ２ O ３ and ZrO ２ Examples include:

[0039] Common boron oxide, B ２ O ３Since B has a low melting point of 450°C, it precipitates slowly during the film formation process by sputtering, and exists in a liquid state between the columnar CoPtX alloy crystal grains while the CoPtX alloy crystal grains are growing into columnar crystals. ２ O ３ The oxides precipitate to form grain boundaries that separate the columnarly grown CoPtX alloy crystal grains, and in the granular structure of the magnetic thin film, they become a non-magnetic matrix that separates the magnetic crystal grains (micro magnets).Increasing the oxide content in the magnetic thin film is preferable because it makes it easier to reliably separate the magnetic crystal grains and makes it easier to separate the magnetic crystal grains.From this point of view, the oxide content contained in the sputtering target according to the first embodiment is preferably 25 vol% or more, more preferably 28 vol% or more, and even more preferably 29 vol% or more.However, if the oxide content in the magnetic thin film is too high, the oxides may be mixed into the CoPtX alloy crystal grains (magnetic crystal grains), adversely affecting the crystallinity of the CoPtX alloy crystal grains (magnetic crystal grains), and the proportion of structures other than hcp in the CoPtX alloy crystal grains (magnetic crystal grains) may increase.In addition, the number of magnetic crystal grains per unit area in the magnetic thin film decreases, making it difficult to increase the recording density. From these points of view, the content of the oxide phase contained in the sputtering target according to the first embodiment is preferably 40 vol % or less, more preferably 35 vol % or less, and even more preferably 31 vol % or less.

[0040] In the sputtering target according to the first embodiment, the total content ratio of the metal phase components and the total content ratio of the oxide phase components relative to the entire sputtering target are determined depending on the component composition of the desired magnetic thin film and are not particularly limited, but the total content ratio of the metal phase components relative to the entire sputtering target can be, for example, 89.4 mol% or more and 96.4 mol% or less, and the total content ratio of the oxide phase components relative to the entire sputtering target can be, for example, 3.6 mol% or more and 11.6 mol% or less.

[0041] Although the microstructure of the sputtering target according to the first embodiment is not particularly limited, it is preferable that the microstructure be such that the metal phase and the oxide phase are finely dispersed in each other. By using such a microstructure, defects such as nodules and particles are less likely to occur during sputtering.

[0042] The sputtering target according to the first embodiment can be manufactured, for example, as follows.

[0043] A molten CoPt alloy is prepared by weighing each metal component to obtain a predetermined composition. The molten CoPt alloy is then gas atomized to produce atomized CoPt alloy powder. The atomized CoPt alloy powder is then classified to a predetermined particle size or less (e.g., 106 μm or less).

[0044] The prepared CoPt alloy atomized powder is mixed with one or more X metal powders selected from V and Mn, B ２ O ３ powder, and optionally other oxide powders (e.g., TiO ２ powder, SiO ２ Powder, Ta ２ O ５ powder, Cr ２ O ３ powder, Al ２ O ３ Powder, ZrO ２ powder, Nb ２ O ５ powder, MnO powder, Mn ３ O ４ powder, CoO powder, Co ３ O ４ powder, NiO powder, ZnO powder, Y ２ O ３ Powder, MoO ２ Powder, WO ３ Powder, La ２ O ３ powder, CeO ２ powder, Nd ２ O ３ Powder, Sm ２ O ３ Powder, Eu ２ O ３ powder, Gd ２ O ３powder, Yb ２ O ３ powder, and Lu ２ O ３ The CoPt alloy atomized powder, X metal powder and B powder are added and mixed and dispersed in a ball mill to prepare a mixed powder for pressure sintering. ２ O ３ The powder, and if necessary, other oxide powders are mixed and dispersed in a ball mill to obtain the CoPt alloy atomized powder, the X metal powder, and the B ２ O ３ A mixed powder for pressure sintering can be prepared in which the powder and, if necessary, other oxide powders are finely dispersed.

[0045] In the magnetic thin film produced using the obtained sputtering target, B ２ O ３ In addition, in order to easily separate the magnetic crystal grains by using other oxides as needed, the CoPtX alloy crystal grains (magnetic crystal grains) are likely to have an hcp structure, and the recording density can be increased, B ２ O ３ The volume fraction of the powder and, if necessary, other oxide powders in the entire mixed powder for pressure sintering is preferably 25 vol% or more and 40 vol% or less, more preferably 28 vol% or more and 35 vol% or less, and even more preferably 29 vol% or more and 31 vol% or less.

[0046] The prepared mixed powder for pressure sintering is pressure sintered by, for example, a vacuum hot press method to form a sputtering target. The mixed powder for pressure sintering is mixed and dispersed in a ball mill, and contains the CoPt alloy atomized powder, the X metal powder, and the B ２ O ３ Since the powder and, if necessary, other oxide powders are finely dispersed in each other, when sputtering is performed using the sputtering target obtained by this manufacturing method, problems such as the generation of nodules or particles are unlikely to occur. Note that the method for pressure sintering the mixed powder for pressure sintering is not particularly limited, and a method other than vacuum hot pressing may be used, such as HIP.

[0047] When preparing the mixed powder for pressure sintering, it is not limited to atomized powder, and powder of each metal may be used. In this case, each metal powder and B ２ O ３ The powder and, if necessary, other oxide powders can be mixed and dispersed in a ball mill to prepare a mixed powder for pressure sintering.

[0048] The other oxides may be formed by oxidizing at least a portion of Co, V and Mn, which are raw materials for the metal phase, during the preparation of the mixed powder for pressure sintering or during sintering.

[0049] (2) Second Embodiment A sputtering target for a magnetic recording medium according to a second embodiment of the present invention is characterized by comprising a metal phase containing at least one element selected from Mn and V, at least one element selected from Cr and Ru, Pt, and the balance being Co and unavoidable impurities, and an oxide phase containing at least B and O.

[0050] The target of the second embodiment preferably contains a metal phase consisting of 1 mol % or more and 30 mol % or less of Pt, more than 0.5 mol % and 30 mol % or less of at least one selected from Cr and Ru, 0.5 mol % or more and 10 mol % or less of at least one selected from Mn and V, and the remainder being Co and unavoidable impurities, and contains 25 vol % or more and 40 vol % or less of an oxide containing at least B and O relative to the entire sputtering target for a magnetic recording medium.

[0051] The oxide phase containing B and O means a phase containing boron oxide. ２ O ３ However, since it is difficult to analyze non-stoichiometric boron oxides themselves, the ICP analysis of boron oxides assumes that the total amount of identified B is B. ２ O ３ In this specification, boron oxide is also referred to as B ２ O ３ It will be explained as follows.

[0052] One or more elements selected from Mn and V (hereinafter also referred to as "X"), one or more elements selected from Cr and Ru (hereinafter also referred to as "M"), Co, and Pt are components of magnetic crystal grains (micro-magnets) in the granular structure of the magnetic thin film formed by sputtering. Hereinafter in this specification, the magnetic crystal grains of the second embodiment will also be referred to as "CoPtXM alloy crystal grains."

[0053] Co is a ferromagnetic metal element that plays a central role in the formation of magnetic crystal grains (micromagnets) in the granular structure of the magnetic thin film. From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPtXM alloy crystal grains (magnetic crystal grains) in the magnetic thin film obtained by sputtering and maintaining the magnetism of the CoPtXM alloy crystal grains (magnetic crystal grains) in the obtained magnetic thin film, the Co content in the sputtering target according to the second embodiment is preferably 25 mol % to 98 mol % of the total metal components.

[0054] Pt has the function of reducing the magnetic moment of the alloy by alloying with Co, X, and M within a predetermined composition range, and also plays a role in adjusting the magnetic strength of the magnetic crystal grains. From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPtXM alloy crystal grains (magnetic crystal grains) in the magnetic thin film obtained by sputtering and from the viewpoint of adjusting the magnetism of the CoPtXM alloy crystal grains (magnetic crystal grains) in the obtained magnetic thin film, the content of Pt in the sputtering target according to the second embodiment is preferably 1 mol % to 30 mol % of the total metal phase components.

[0055] At least one element selected from Cr and Ru has the function of reducing the magnetic moment of Co by alloying with Co within a predetermined composition range, and thus plays a role in adjusting the magnetic strength of the magnetic crystal grains. From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPtXM alloy crystal grains (magnetic crystal grains) in the magnetic thin film obtained by sputtering and maintaining the magnetic properties of the CoPtXM alloy crystal grains in the obtained magnetic thin film, the content of at least one element selected from Cr and Ru in the sputtering target according to the second embodiment is preferably more than 0.5 mol% and not more than 30 mol% of the total metal phase components. Cr and Ru can be used alone or in combination, and together with Co and Pt, they form the metal phase of the sputtering target. The examples described below demonstrate that Ru can reduce the Ku decrease more than Cr, so Ru is more preferable.

[0056] The inventors have found that V and Mn have the function of improving the separation of CoPtXM alloy crystal grains (magnetic crystal grains) due to the oxide phase in the magnetic thin film, thereby reducing intergranular exchange coupling. On the other hand, they do not significantly reduce the magnetocrystalline anisotropy constant Ku. The examples below show that V reduces α more significantly and Ku less significantly than Mn, so V is more preferable.

[0057] The content of X in the sputtering target according to the second embodiment is preferably 0.5 mol% or more and 10 mol% or less, more preferably 1 mol% or more and less than 10 mol%, and particularly preferably 5 mol% or less, relative to the total metal phase components. Mn and V can be contained alone or in combination as metal phase components of the sputtering target. In particular, the combination of V and Mn is preferable because it can reduce intergranular exchange coupling and improve uniaxial magnetic anisotropy.

[0058] The oxide phase becomes a non-magnetic matrix that separates magnetic crystal grains (micro-magnets) in the granular structure of the magnetic thin film. The oxide phase of the sputtering target according to the second embodiment contains at least B and O. Other oxide components may include an oxide of at least one element selected from V, Ru, Ti, Si, Ta, Cr, Al, Nb, Mn, Co, Ni, Zn, Y, Mo, W, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr. Specific examples of other oxides include VO. ２ , V.O. ３ , V ２ O ５ , RuO ２ , TiO ２ , SiO ２ , Ta ２ O ５ , Cr ２ O ３ , Al ２ O ３ , Nb ２ O ５ , MnO, Mn ３ O ４ , CoO, Co ３ O ４ , NiO, ZnO, Y ２ O ３ , MoO ２ , W.O. ３ , La ２ O ３ , CeO ２ , Nd ２ O ３ , Sm ２ O ３ , Eu ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Lu ２ O ３ and ZrO ２ Examples include:

[0059] Common boron oxide, B ２ O ３Since B has a low melting point of 450°C, it precipitates slowly during the film formation process by sputtering, and exists in a liquid state between the columnar CoPtXM alloy crystal grains while the CoPtXM alloy crystal grains are growing into a columnar shape. ２ O ３ The oxides precipitate to form grain boundaries separating the columnarly grown CoPtXM alloy crystal grains, and in the granular structure of the magnetic thin film, they become a non-magnetic matrix separating the magnetic crystal grains (micro magnets).Increasing the oxide content in the magnetic thin film is preferable because it makes it easier to reliably separate the magnetic crystal grains and makes it easier to separate the magnetic crystal grains.From this point of view, the oxide content contained in the sputtering target according to the second embodiment is preferably 25 vol% or more, more preferably 28 vol% or more, and even more preferably 29 vol% or more.However, if the oxide content in the magnetic thin film is too high, the oxides may be mixed into the CoPtXM alloy crystal grains (magnetic crystal grains), adversely affecting the crystallinity of the CoPtXM alloy crystal grains (magnetic crystal grains), and the proportion of structures other than hcp in the CoPtXM alloy crystal grains (magnetic crystal grains) may increase.In addition, the number of magnetic crystal grains per unit area in the magnetic thin film decreases, making it difficult to increase the recording density. From these points of view, the content of the oxide phase contained in the sputtering target according to the second embodiment is preferably 40 vol % or less, more preferably 35 vol % or less, and even more preferably 31 vol % or less.

[0060] In the sputtering target according to the second embodiment, the total content ratio of the metal phase components and the total content ratio of the oxide phase components relative to the entire sputtering target are determined depending on the component composition of the desired magnetic thin film and are not particularly limited, but the total content ratio of the metal phase components relative to the entire sputtering target can be, for example, 88.2 mol% or more and 96.4 mol% or less, and the total content ratio of the oxide phase components relative to the entire sputtering target can be, for example, 3.6 mol% or more and 11.8 mol% or less.

[0061] Although the microstructure of the sputtering target according to the second embodiment is not particularly limited, it is preferable that the microstructure be such that the metal phase and the oxide phase are finely dispersed in each other. By using such a microstructure, defects such as nodules and particles are less likely to occur during sputtering.

[0062] The sputtering target according to the second embodiment can be manufactured, for example, as follows.

[0063] A molten CoPtM alloy is prepared by weighing out one or more M metal powders selected from Cr and Ru, Co, and Pt to obtain a predetermined composition. The resulting molten CoPtM alloy is then gas atomized to produce atomized CoPtM alloy powder. The atomized CoPtM alloy powder is then classified to a particle size of a predetermined size (e.g., 106 μm or less).

[0064] The prepared CoPtM alloy atomized powder is added with one or more X metal powders selected from V and Mn, B ２ O ３ powder, and optionally other oxide powders (e.g., TiO ２ powder, SiO ２ Powder, Ta ２ O ５ powder, Cr ２ O ３ powder, Al ２ O ３ Powder, ZrO ２ powder, Nb ２ O ５ powder, MnO powder, Mn ３ O ４ powder, CoO powder, Co ３ O ４ powder, NiO powder, ZnO powder, Y ２ O ３ Powder, MoO ２ Powder, WO ３ Powder, La ２ O ３ powder, CeO ２ powder, Nd ２ O ３ Powder, Sm ２ O ３ Powder, Eu ２ O ３ powder, Gd２ O ３ powder, Yb ２ O ３ powder, and Lu ２ O ３ The CoPtM alloy atomized powder, X metal powder, and B powder are added and mixed and dispersed in a ball mill to prepare a mixed powder for pressure sintering. ２ O ３ The powder and, if necessary, other oxide powders are mixed and dispersed in a ball mill to obtain CoPtM alloy atomized powder, X metal powder, and B ２ O ３ A mixed powder for pressure sintering can be prepared in which the powder and, if necessary, other oxide powders are finely dispersed.

[0065] In the magnetic thin film produced using the obtained sputtering target, B ２ O ３ In addition, in order to easily separate the magnetic crystal grains by using other oxides as needed, the CoPtXM alloy crystal grains (magnetic crystal grains) are likely to have an hcp structure, and in order to increase the recording density, B ２ O ３ The volume fraction of the powder and, if necessary, other oxide powders in the entire mixed powder for pressure sintering is preferably 25 vol% or more and 40 vol% or less, more preferably 28 vol% or more and 35 vol% or less, and even more preferably 29 vol% or more and 31 vol% or less.

[0066] The prepared mixed powder for pressure sintering is pressure sintered by, for example, a vacuum hot press method to form a sputtering target. The mixed powder for pressure sintering is mixed and dispersed in a ball mill, and the mixed powder is a mixture of CoPtM alloy atomized powder, X metal powder, and B ２ O ３ Since the powder and, if necessary, other oxide powders are finely dispersed in each other, when sputtering is performed using the sputtering target obtained by this manufacturing method, problems such as the generation of nodules or particles are unlikely to occur. Note that the method for pressure sintering the mixed powder for pressure sintering is not particularly limited, and a method other than vacuum hot pressing may be used, such as HIP.

[0067] When preparing the mixed powder for pressure sintering, it is not limited to atomized powder, and powder of each metal may be used. In this case, each metal powder and, if necessary, B powder and B ２ O ３ The powder and, if necessary, other oxide powders can be mixed and dispersed in a ball mill to prepare a mixed powder for pressure sintering.

[0068] The other oxides may be formed by oxidizing at least a portion of Co, Cr, Ru, V and Mn, which are raw materials for the metal phase, during the preparation of the mixed powder for pressure sintering or during sintering.

[0069] (3) Third Embodiment A sputtering target for a magnetic recording medium according to a third embodiment of the present invention is characterized by comprising a metal phase containing at least one selected from Mn and V, Pt, and the remainder containing Co and unavoidable impurities, and an oxide phase.

[0070] The target of the third embodiment preferably contains a metal phase consisting of 1 mol % to 30 mol % of Pt, 0.5 mol % to 10 mol % of at least one selected from Mn and V, and the remainder Co and unavoidable impurities, and contains 25 vol % to 40 vol % of oxides relative to the entire sputtering target for a magnetic recording medium.

[0071] The third embodiment is similar to the first embodiment except that the oxide phase is not limited to one containing boron oxide, and therefore the explanation will be omitted here. Instead, the reason why the oxide phase is not limited to one containing boron oxide will be explained.

[0072] As will be apparent from the examples described later, it has been found that if the metal phase contains V or Mn, the reduction in Ku is small and α is reduced even if the oxide does not contain boron oxide. ２ and TiO ２ When the oxide is contained, not only α decreases but also Ku increases, which is particularly preferable. ２ , TiO ２ , Cr ２ O ３ , Nb ２ O ５, Ta ２ O ５ , MoO ３ , W.O. ３ , CoO, B ２ O ３ It has been confirmed that when any combination of these is used, α decreases and the decrease in Ku is small. The oxide precipitates to form grain boundaries that separate the CoPtX alloy crystal grains that have grown into columnar crystals, and becomes a non-magnetic matrix that separates the magnetic crystal grains (micro-magnets) in the granular structure of the magnetic thin film.

[0073] The sputtering target for a magnetic recording medium according to the third embodiment may further contain, in addition to the oxides described above, an oxide of at least one element selected from V, Ru, Al, Mn, Co, Ni, Zn, Y, Mo, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr. Specific examples of other oxides include VO ２ , V.O. ３ , V ２ O ５ , RuO ２ , Al ２ O ３ , MnO, Mn ３ O ４ , Co ３ O ４ , NiO, ZnO, Y ２ O ３ , MoO ２ , La ２ O ３ , CeO ２ , Nd ２ O ３ , Sm ２ O ３ , Eu ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Lu ２ O ３ and ZrO ２ Examples include:

[0074] (4) Fourth Embodiment A sputtering target for a magnetic recording medium according to a fourth embodiment of the present invention is characterized by comprising a metal phase containing at least one element selected from Mn and V, at least one element selected from Cr and Ru, Pt, and the balance being Co and unavoidable impurities, and an oxide phase.

[0075] The target of the fourth embodiment contains a metal phase consisting of 1 mol % or more and 30 mol % or less of Pt, more than 0.5 mol % and 30 mol % or less of at least one selected from Cr and Ru, 0.5 mol % or more and 10 mol % or less of at least one selected from Mn and V, and the remainder being Co and unavoidable impurities, and preferably contains 25 vol % or more and 40 vol % or less of oxides relative to the entire sputtering target for a magnetic recording medium.

[0076] The fourth embodiment is similar to the second embodiment except that it is not limited to an oxide phase containing boron oxide, and is similar to the third embodiment in that it may contain any oxide, and therefore a description thereof will be omitted.

[0077] The present invention will be further described below using examples and comparative examples.

[0078] Example 1 The overall composition of the target produced in Example 1 was (75Co-20Pt-5V)-30 vol% B. ２ O ３ (Metal components are expressed as atomic ratios), and expressed as a molar ratio, it is 92.47(75Co-20Pt-5V)-7.53B ２ O ３ is.

[0079] In producing the target according to Example 1, first, a 50Co-50Pt alloy and a 100Co atomized powder were produced. Specifically, the metals in the atomized alloy powder were weighed so that the composition was 50 at % Co and 50 at % Pt, and both compositions were heated to 1500°C or higher to form molten alloys, which were then gas atomized to produce the 50Co-50Pt alloy and 100Co atomized powders, respectively.

[0080] The produced 50Co-50Pt alloy and 100Co atomized powders were classified using a 150 mesh sieve to obtain 50Co-50Pt alloy and 100Co atomized powders with particle sizes of 106 μm or less, respectively.

[0081] (75Co-20Pt-5V)-30vol%B ２ O ３ The 50Co-50Pt alloy and 100Co atomized powder after classification were mixed with V powder and B powder to obtain the composition. ２ O ３ The powder was added and mixed and dispersed in a ball mill to obtain a mixed powder for pressure sintering.

[0082] The obtained mixed powder for pressure sintering was used, and the sintering temperature was 810°C, the sintering pressure was 24.5 MPa, the sintering time was 30 minutes, and the atmosphere was 5 × 10 −２ The sintered body test piece (φ30 mm) was prepared by hot pressing under vacuum conditions of 0.1 Pa or less. The relative density of the prepared sintered body test piece was 98.8%. The calculated density was 8.90 g / cm. ３ The cross section in the thickness direction of the obtained sintered body test piece was mirror-polished and observed using a scanning electron microscope (SEM: JEOL JCM-6000Plus) at an acceleration voltage of 15 keV. The results are shown in Figure 1. Furthermore, the composition of the cross section was analyzed using an energy dispersive X-ray spectrometer (EDS) installed in the same device. The results are shown in Figure 2. These results indicate that the metal phase (75Co-20Pt-5V alloy phase) and the oxide phase (B ２ O ３ The sintered body test pieces were subjected to ICP analysis, and the results are shown in Table 3.

[0083] Next, the prepared mixed powder for pressure sintering was used, and the sintering temperature was 810°C, the sintering pressure was 24.5 MPa, the sintering time was 60 minutes, and the atmosphere was 5 × 10 −２ The mixture was hot pressed under vacuum conditions of 100 Pa or less to prepare one target having dimensions of φ153.0×1.0 mm+φ161.0×4.0 mm. The relative density of the prepared target was 98.3%.

[0084] The prepared target was used for sputtering in a DC sputtering device (ES-3100W manufactured by Eiko Engineering), and (75Co-20Pt-5V)-30 vol% B ２ O ３ A magnetic thin film consisting of Ta was formed on a glass substrate to prepare a sample for measuring magnetic properties and a sample for observing the structure. Specifically, a Ta film was formed to a thickness of 5 nm under conditions of an Ar gas pressure of 0.6 Pa and an input power of 500 W as a layer to ensure adhesion between the glass substrate and the metal film. Next, a Ni film was formed as a seed layer for forming an orientation film. ９０ W １０ A 6 nm thick film of Co-25Cr-50Ru-30 vol% TiO was then formed at 0.6 Pa and 500 W. Subsequently, a 10 nm thick film of Ru was formed at 0.6 Pa and 500 W as a base for the hcp structure, and then a 10 nm thick film of Ru was formed at 8.0 Pa and 500 W to form a surface irregularity. Furthermore, a Co-25Cr-50Ru-30 vol% TiO film was then formed to improve the separation of the magnetic columns. ２ A 1 nm thick film of (Co-20Pt-5V)-30 vol % B was formed on the magnetic layer at 0.6 Pa and 300 W. ２ O ３ The layers were deposited at 4.0 Pa and 500 W to thicknesses of 4 nm, 8 nm, 12 nm, and 16 nm, respectively. Finally, a surface protection layer of C was deposited at 0.6 Pa and 300 W to thicknesses of 7 nm. The layer structures of these samples are listed in order from the side closest to the glass substrate: Ta (5 nm, 0.6 Pa) / Ni ９０ W １０ (6nm, 0.6Pa) / Ru (10nm, 0.6Pa) / Ru (10nm, 8.0Pa) / Co-25Cr-50Ru-30vol%TiO ２ (1 nm, 4.0 Pa) / (Co-20Pt-5V)-30vol%B ２ O ３ (Y nm (Y = 4, 8, 12 or 16), 4 Pa) / C (7 nm, 0.6 Pa). The number on the left in the parentheses indicates the film thickness, and the number on the right indicates the pressure of the Ar atmosphere when sputtering was performed. The magnetic thin film formed using the target prepared in Example 1 was a CoPtV alloy-oxide (B ２ O ３) is a magnetic thin film that will become the recording layer of a perpendicular magnetic recording medium. Note that the substrate was not heated when this magnetic thin film was formed, and the film was formed at room temperature.

[0085] The magnetic properties of the obtained magnetic property measurement samples were measured using a vibrating sample magnetometer (VSM: Model TM-VSM211483-HGC, manufactured by Tamagawa Seisakusho Co., Ltd.), a torque magnetometer (Model TM-TR2050-HGC, manufactured by Tamagawa Seisakusho Co., Ltd.), and a polar Kerr effect measuring device (MOKE: Model BH-810CPM-CPC, manufactured by NeoArc Co., Ltd.).

[0086] 3 shows an example of the granular medium magnetization curve (Y=12 nm) of the magnetic property measurement sample of Example 1. The horizontal axis of Fig. 3 represents the strength of the applied magnetic field, and the vertical axis of Fig. 3 represents the strength of magnetization per unit volume.

[0087] From the measurement results of the granular medium magnetization curve of the magnetic property measurement sample, the saturation magnetization (Ms), coercive force (Hc), reverse magnetic domain nucleation field (Hn), and the gradient (α) of the point where the curve intersects with the horizontal axis were obtained. In addition, the magnetocrystalline anisotropy constant (Ku) was measured using a torque magnetometer. These values ​​are shown in Table 1 and Figures 8 to 12 together with the results of other examples and comparative examples.

[0088] Furthermore, an X-ray diffraction device (XRD: SmartLab manufactured by Rigaku Corporation) and a transmission electron microscope (TEM: H-9500 manufactured by Hitachi High-Technologies Corporation) were used to evaluate the structure of the obtained samples for texture observation (evaluation of the particle size of the magnetic crystal grains, etc.). The XRD profile in the direction perpendicular to the film surface is shown in FIG. 6 and Table 2, and the TEM image is shown in FIG. 7.

[0089] (Example 2) The overall composition of the target produced in Example 2 was (75Co-20Pt-5Mn)-30 vol% B. ２ O ３ (Metal components are expressed as atomic ratios), and expressed as a molar ratio, it is 92.51(75Co-20Pt-5Mn)-7.49B ２ O ３A sample for measuring magnetic properties and a sample for observing the structure were prepared and observed in the same manner as in Example 1, except that the composition of the target was changed from that in Example 1. The results are shown in Figures 4 and 5. The Mn powder used had an average particle size of 3 μm or less, and the sintering temperature was 840°C, the sintering pressure was 24.5 MPa, the sintering time was 30 minutes, and the atmosphere was 5 × 10 −２ The sintered body was subjected to hot pressing under vacuum conditions of 0.1 Pa or less to prepare a sintered body test piece (φ30 mm). The relative density of the prepared sintered body test piece was 102.6%. The calculated density was 8.97 g / cm. ３ When the cross section of the obtained sintered body test piece in the thickness direction was observed with a metallurgical microscope, it was found that the metal phase (75Co-20Pt-5Mn alloy phase) and the oxide phase (B ２ O ３ The sintered body test pieces were subjected to ICP analysis, and the results are shown in Table 3.

[0090] Next, the prepared mixed powder for pressure sintering was used, and the sintering temperature was 840°C, the sintering pressure was 24.5 MPa, the sintering time was 60 min, and the atmosphere was 5 × 10 −２ The mixture was subjected to hot pressing under vacuum conditions of 100 Pa or less to prepare a target having dimensions of φ153.0×1.0 mm+φ161.0×4.0 mm. The relative density of the prepared target was 104.8%.

[0091] Next, the magnetic properties of the film were evaluated and the structure was observed in the same manner as in Example 1. The results of the magnetic property measurements, along with the target composition, are shown in Table 1 and Figures 8 to 12. The XRD profile in the direction perpendicular to the film surface for the structure observation is shown in Figure 6 and Table 2, and the TEM image is shown in Figure 7.

[0092] (Comparative Example 1) The composition of the entire target was (80Co-20Pt)-30 vol% B ２ O ３(Metal components are shown in atomic ratios) Sintered test pieces and targets were prepared in the same manner as in Examples 1 and 2, and magnetic thin films were formed and evaluated. The measurement results of the magnetic properties are shown in Table 1 and Figures 8 to 12 together with the composition of the target. The XRD profile in the direction perpendicular to the film surface of the microstructure observation is shown in Figure 6, the peak position (2θ) and C-axis lattice constant of CoPt(002) read from the XRD profile are shown in Table 2, and a TEM image is shown in Figure 7. The results of ICP analysis of the obtained sintered test pieces are shown in Table 3.

[0093] The meanings of the abbreviations in Table 1 are as follows: Ｍａｇ１ : film thickness of the magnetic recording layer in the laminated film M ｓ Ｇｒａｉｎ : Saturation magnetization of only the magnetic particles in the magnetic layer of the laminated film H ｃ : Coercive force measured by Kerr H ｎ : Nucleation magnetic field measured by Kerr α: Slope of the point where the magnetization curve measured by Kerr intersects with the horizontal axis (applied magnetic field) H ｃ -H ｎ : Difference between coercivity measured by Kerr and nucleation field K ｕ Ｇｒａｉｎ : Magnetocrystalline anisotropy constant of only the magnetic grains in the magnetic layer of the laminated film

[0094]

[0095]

[0096]

[0097] From FIG. 6 and Table 2, it can be seen that the CoPt (002) peak in Example 1 (V) and Example 2 (Mn) is shifted to a lower angle than that in Comparative Example 1 (Co). This indicates that at least a portion of the V or Mn is substituted with Co. However, the change in the C-axis lattice constant of the CoPt phase calculated from the peak position is 0.1 Å or less. Furthermore, no structural change in the CoPt phase is observed. On the other hand, no peak shift is observed for Ru and NiW.

[0098] 7, it can be seen that the gaps between adjacent magnetic columns extend deeper in the depth direction in the magnetic thin film containing V or Mn compared to the magnetic thin film not containing V or Mn (X=Co). This confirms that the use of a target containing V or Mn improves the separation of magnetic crystal grains.

[0099] As can be seen from FIG. 8, a slight increase in Ms is confirmed in Example 1 (V) and Example 2 (Mn) when the film thickness is 4 nm compared to Comparative Example 1 (Co), but when the film thickness is 8 nm or more, it is almost the same, and it is clear that the magnetism of the CoPtX alloy crystal grains (magnetic crystal grains) can be maintained.

[0100] 9, magnetic thin films containing V or Mn exhibit a Hc that is comparable to or slightly lower than that of magnetic thin films (X=Co) that do not contain V or Mn. However, further improvement can be expected by optimizing the composition or by introducing V and Mn in combination.

[0101] 10, a decrease in Hn is confirmed in Example 1 (V) compared to Comparative Example 1 (Co). A further decrease in Hn is confirmed in Example 2 (Mn) compared to Example 1 (V). This suggests that the separation of magnetic crystal grains is improved.

[0102] From FIG. 11, it can be seen that the magnetic thin film containing V or Mn exhibits a lower α than the magnetic thin film not containing V or Mn (X=Co), and the separation of the magnetic crystal grains is improved.

[0103] From FIG. 12, it can be seen that the magnetic thin film containing V or Mn exhibits the same Ku as the magnetic thin film not containing V or Mn (X=Co), and maintains a high uniaxial magnetic anisotropy.

[0104] (Examples 3 to 4, Comparative Example 2) Oxide phase: 30 vol% SiO ２ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 4.

[0105] The metal phase contains V or Mn, and the oxide phase contains SiO ２ In Examples 3 and 4 including the above, α is reduced and Ku is increased compared to Comparative Example 2, and it can be said that the separation of the magnetic crystal grains is improved and high uniaxial magnetic anisotropy is exhibited.

[0106] (Examples 5 to 6, Comparative Example 3) The oxide phase was 30 vol% TiO ２ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 4.

[0107] The metal phase contains V or Mn, and the oxide phase contains TiO ２ In Examples 5 and 6 including the above, α was reduced and Ku was increased compared to Comparative Example 3, and it can be said that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was exhibited.

[0108] (Examples 7 to 8, Comparative Example 4) The oxide phase was 30 vol % Cr ２ O ３ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 4.

[0109] The metal phase contains V or Mn, and the oxide phase contains Cr. ２ O ３ In Examples 7 and 8 including the above, α was reduced compared to Comparative Example 4, the decrease in Ku was small at 0.95 or less, and it can be said that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was maintained.

[0110] (Examples 9 to 10, Comparative Example 5) Oxide phase containing 30 vol% Nb ２ O ５Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 4.

[0111] The metal phase contains V or Mn, and the oxide phase contains Nb ２ O ５ In Examples 9 and 10 including the above, α is reduced compared to Comparative Example 5, the decrease in Ku is small at 0.39 or less, and it can be said that the separation of the magnetic crystal grains is improved and high uniaxial magnetic anisotropy is maintained.

[0112] (Examples 11 to 12, Comparative Example 6) The oxide phase was 30 vol % Ta ２ O ５ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 4.

[0113] The metal phase contains V or Mn, and the oxide phase contains Ta. ２ O ５ In Examples 11 and 12 including the above, α was reduced compared to Comparative Example 6, the decrease in Ku was small at 0.47 or less, and it can be said that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was maintained.

[0114] (Examples 13 to 14, Comparative Example 7) The oxide phase was 30 vol% MoO ３ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 5.

[0115] The metal phase contains V or Mn, and the oxide phase contains MoO ３In Examples 13 and 14 including the above, α was reduced compared to Comparative Example 7, the decrease in Ku was small at 0.30 or less, and it can be said that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was maintained.

[0116] (Examples 15 to 16, Comparative Example 8) Oxide phase: 30 vol% WO ３ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 5.

[0117] The metal phase contains V or Mn, and the oxide phase contains WO ３ In Examples 15 and 16 including the above, α was reduced compared to Comparative Example 8, and the decrease in Ku was small at 0.51 or less, which means that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was maintained.

[0118] (Examples 17 to 18, Comparative Example 9) Oxide phase 15 vol % B ２ O ３ -15vol%SiO ２ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 5.

[0119] The metal phase contains V or Mn, and the oxide phase contains B. ２ O ３ and SiO ２ In Examples 17 and 18 including the above, α was reduced compared to Comparative Example 9, and the decrease in Ku was small at 0.18 or less, which means that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was maintained.

[0120] (Examples 19 to 20, Comparative Example 10) Oxide phase: 15 vol% SiO ２ -15vol%TiO ２Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 5.

[0121] The metal phase contains V or Mn, and the oxide phase contains SiO ２ and TiO ２ In Examples 19 and 20 including the above, α was reduced compared to Comparative Example 10, and Ku increased or decreased by only 0.01, which is very small, and it can be said that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was exhibited.

[0122] (Examples 21 to 22, Comparative Example 11) Oxide phase 20 vol % B ２ O ３ -5vol% Cr ２ O ３ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 5.

[0123] The metal phase contains V or Mn, and the oxide phase contains B. ２ O ３ and Cr ２ O ３ In Examples 21 and 22 including the above, α was reduced compared to Comparative Example 11, the decrease in Ku was small at 0.54 or less, and it can be said that the separation of the magnetic crystal grains was improved and high uniaxial magnetic anisotropy was maintained.

[0124] (Examples 23 to 24, Comparative Example 12) Oxide phase: 10 vol% SiO ２ -10vol%TiO ２ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1, except that -10 vol% CoO was used, a magnetic layer having a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), gradient of the point where the layer intersects with the horizontal axis (α), and magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 5.

[0125] The metal phase contains V or Mn, and the oxide phase contains SiO ２ , TiO ２ In Examples 23 and 24 containing CoO, α was reduced compared to Comparative Example 12, the decrease in Ku was small at 0.35, and it can be said that the separation of magnetic crystal grains was improved and high uniaxial magnetic anisotropy was exhibited.

[0126] (Examples 25 to 26, Comparative Example 13) Oxide phase: 20 vol% SiO ２ -5vol% TiO ２ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1, except that -5 vol% CoO was used instead, a magnetic layer having a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), gradient of the point where the layer intersects with the horizontal axis (α), and magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0127] The metal phase contains V or Mn, and the oxide phase contains SiO ２ , TiO ２ In Examples 25 and 26 containing CoO, α was reduced compared to Comparative Example 13, the decrease in Ku was small at 1.02, and it can be said that the separation of magnetic crystal grains was improved and high uniaxial magnetic anisotropy was exhibited.

[0128] (Examples 27 to 28, Comparative Example 14) Oxide phase 20 vol % B ２ O ３ -5 vol% SiO ２ -5vol% Cr ２ O ３ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1 except for replacing the target with the coercive force (Hc), the nucleation magnetic field (Hn), the gradient of the point where the magnetic layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured in the same manner as in Example 1. The results are shown in Table 6.

[0129] The metal phase contains V or Mn, and the oxide phase contains SiO ２ , TiO ２In Examples 27 to 28 containing CoO, α was reduced compared to Comparative Example 14, and Ku either increased or showed a very small decrease of 0.19, which indicates that the separation of magnetic crystal grains was improved and high uniaxial magnetic anisotropy was exhibited.

[0130] (Examples 29 to 30, Comparative Example 15) Oxide phase 20 vol % B ２ O ３ -3 vol% SiO ２ -3 vol% TiO ２ Using a sputtering target for magnetic recording media prepared in the same manner as in Examples 1 and 2 and Comparative Example 1, except that -10 vol% CoO was used, a magnetic layer having a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), gradient of the point where the layer intersects with the horizontal axis (α), and magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0131] The metal phase contains V or Mn, and the oxide phase contains B. ２ O ３ , SiO ２ , TiO ２ It can be said that Examples 29 and 30 containing CoO have a smaller α, an increased Ku, improved separation of magnetic crystal grains, and exhibit high uniaxial magnetic anisotropy than Comparative Example 15.

[0132] (Example 31) A sputtering target for magnetic recording media was prepared in the same manner as in Example 1, except that the metal phase composition was changed to 79Co-20Pt-1V. A magnetic layer with a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), the gradient of the point where the layer intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0133] In Example 31 containing 1 mol % V in the metal phase, the decrease in α was smaller than in Example 1 containing 5 mol % V, but the decrease in Ku was as small as 0.04.

[0134] (Example 32) A sputtering target for magnetic recording media was prepared in the same manner as in Example 2, except that the metal phase composition was changed to 79Co-20Pt-1Mn, and a magnetic layer with a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), gradient of the point where the axis intersects with the horizontal axis (α), and magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0135] In Example 32, in which the metal phase contained 1 mol % of Mn, the decrease in α was smaller than in Example 2, in which the metal phase contained 5 mol % of Mn, but the decrease in Ku was also smaller.

[0136] (Example 33) A sputtering target for magnetic recording media was prepared in the same manner as in Example 1, except that the metal phase composition was changed to 70Co-20Pt-10V, and a magnetic layer with a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), the gradient of the point where the abscissa intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0137] In Example 33 containing 10 mol % of V in the metal phase, α decreased similarly to Example 1 containing 5 mol % of V, but the decrease in Ku was greater.

[0138] (Example 34) A sputtering target for magnetic recording media was prepared in the same manner as in Example 2, except that the metal phase composition was changed to 70Co-20Pt-10Mn. A magnetic layer with a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation field (Hn), the gradient of the point where the axis intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0139] In Example 34, in which the metal phase contained 10 mol % of Mn, α decreased similarly to Example 2, in which the metal phase contained 5 mol % of Mn, but the decrease in Ku was greater.

[0140] (Comparative Example 16) Using a sputtering target for magnetic recording media prepared in the same manner as in Example 1, except that the metal phase composition was changed to 65Co-20Pt-15V, a magnetic layer with a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation magnetic field (Hn), the gradient of the point where it intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured. The results are shown in Table 6.

[0141] Comparative Example 16 containing 15 mol % of V exhibited a significantly larger decrease in Ku than Examples 1, 31 and 33 containing 1 to 10 mol % of V.

[0142] (Comparative Example 17) Using the sputtering target for magnetic recording media prepared in the same manner as in Example 2, except that the metal phase composition was changed to 65Co-20Pt-15Mn, a magnetic layer with a thickness of 8 nm was formed in the same manner as in Example 1, and the coercive force (Hc), nucleation magnetic field (Hn), the gradient of the point where the axis intersects with the horizontal axis (α), and the magnetocrystalline anisotropy constant (Ku) were measured.The results are shown in Table 6.

[0143] Comparative Example 17 containing 15 mol % of Mn showed a significantly larger decrease in Ku than Examples 2, 32 and 34 containing 1 to 10 mol % of Mn.

[0144] (Example 35~36, Comparative Example 18) In Example 35, metal phase composition is changed to 75Co-20Pt-2Cr-3V, except that in Example 1, in Example 36, metal phase composition is changed to 75Co-20Pt-2Cr-3Mn, except that in Example 2, in Comparative Example 18, metal phase composition is changed to 75Co-20Pt-5Cr, except that in Comparative Example 1, use the sputtering target for magnetic recording medium prepared respectively, and in Example 1, form a magnetic layer with a thickness of 8nm, and measure coercive force (Hc), nucleation magnetic field (Hn), the gradient (α) of the point where it intersects with the horizontal axis, and magnetic crystal anisotropy constant (Ku).Results are shown in Table 6.

[0145] Examples 35 and 36, which further contain Cr in the metal phase composition, show a smaller decrease in Ku than Examples 1 and 2, and exhibit improved separation of magnetic crystal grains and high uniaxial magnetic anisotropy.

[0146] (Example 37~38, Comparative Example 19) In Example 37, metal phase composition is changed to 75Co-20Pt-2Ru-3V, but is similar to Example 1; in Example 38, metal phase composition is changed to 75Co-20Pt-2Ru-3Mn, but is similar to Example 2; in Comparative Example 19, metal phase composition is changed to 75Co-20Pt-5Ru, but is similar to Comparative Example 1; use the sputtering target for magnetic recording medium prepared respectively, and form the magnetic layer of thickness 8nm in the same manner as Example 1, and measure coercive force (Hc), nucleation magnetic field (Hn), the inclination (α) of the point where it intersects with horizontal axis, and crystalline magnetic anisotropy constant (Ku).Results are shown in Table 6.

[0147] Examples 37 and 38, which further contain Ru in the metal phase composition, show a smaller decrease in Ku than Examples 1 and 2, and exhibit improved separation of magnetic crystal grains and high uniaxial magnetic anisotropy.

[0148] From the results shown in Tables 4 to 6, it can be seen that the inclusion of V in the metal phase results in a greater decrease in α and a smaller decrease in Ku than the inclusion of Mn. By including V or Mn, it can be achieved to improve the separation of magnetic crystal grains and maintain high uniaxial magnetic anisotropy, and V can be said to be effective in further improving the separation of magnetic crystal grains and maintaining high uniaxial magnetic anisotropy. Furthermore, it is possible to achieve improvement in the separation of magnetic crystal grains and maintenance of high uniaxial magnetic anisotropy with any oxide, and SiO ２ or TiO ２ It can be said that the effect is even greater when B is included. ２ O ３ By including SiO, the uniaxial magnetic anisotropy (Ku) can be increased. ２ or TiO ２ It has been confirmed that by including [alpha], it is possible to reduce α while maintaining a high uniaxial magnetic anisotropy (Ku).

[0149]

Claims

1. A sputtering target for a magnetic recording medium, comprising a metal phase consisting of at least one selected from Mn and V, Pt, and the balance being Co and inevitable impurities, and an oxide phase containing at least B and O.

2. The sputtering target for a magnetic recording medium according to claim 1, wherein Pt is contained in an amount of 1 mol% or more and 30 mol% or less, and at least one selected from Mn and V is contained in an amount of 0.5 mol% or more and 10 mol% or less, based on the total of the metal phase components of the sputtering target for a magnetic recording medium, and the oxide phase is contained in an amount of 25 vol% or more and 40 vol% or less based on the whole sputtering target for a magnetic recording medium.

3. A sputtering target for a magnetic recording medium, comprising a metal phase consisting of at least one selected from Mn and V, at least one selected from Cr and Ru, Pt, and the balance being Co and inevitable impurities, and an oxide phase containing at least B and O.

4. The sputtering target for a magnetic recording medium according to claim 3, wherein Pt is contained in an amount of 1 mol% or more and 30 mol% or less, at least one selected from Mn and V is contained in an amount of 0.5 mol% or more and 10 mol% or less, and at least one selected from Cr or Ru is contained in an amount exceeding 0.5 mol% and 30 mol% or less, based on the total of the metal phase components of the sputtering target for a magnetic recording medium, and the oxide phase is contained in an amount of 25 vol% or more and 40 vol% or less based on the whole sputtering target for a magnetic recording medium.

5. The sputtering target for a magnetic recording medium according to any one of claims 1 to 4, wherein the oxide phase further contains an oxide of at least one element selected from V, Ru, Ti, Si, Ta, Cr, Al, Nb, Mn, Co, Ni, Zn, Y, Mo, W, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr.

6. A sputtering target for a magnetic recording medium, comprising a metal phase consisting of at least one selected from Mn and V, Pt, and the balance being Co and inevitable impurities, and an oxide phase.

7. The sputtering target for a magnetic recording medium contains 1 mol% or more and 30 mol% or less of Pt, and at least one or more selected from Mn and V in an amount of 0.5 mol% or more and 10 mol% or less, based on the total of the metal phase components of the sputtering target for a magnetic recording medium, and contains the oxide phase in an amount of 25 vol% or more and 40 vol% or less with respect to the whole of the sputtering target for a magnetic recording medium. The sputtering target for a magnetic recording medium according to claim 6, characterized by the above.

8. A sputtering target for a magnetic recording medium comprising a metal phase composed of at least one or more selected from Mn and V, at least one or more selected from Cr and Ru, Pt, and the balance being Co and unavoidable impurities, and an oxide phase.

9. The sputtering target for a magnetic recording medium contains 1 mol% or more and 30 mol% or less of Pt, at least one or more selected from Mn and V in an amount of 0.5 mol% or more and 10 mol% or less, and at least one or more selected from Cr or Ru in an amount exceeding 0.5 mol% and 30 mol% or less, based on the total of the metal phase components of the sputtering target for a magnetic recording medium, and contains the oxide phase in an amount of 25 vol% or more and 40 vol% or less with respect to the whole of the sputtering target for a magnetic recording medium. The sputtering target for a magnetic recording medium according to claim 7, characterized by the above.

10. The oxide phase further contains an oxide of at least one element selected from B, V, Ru, Ti, Si, Ta, Cr, Al, Nb, Mn, Co, Ni, Zn, Y, Mo, W, La, Ce, Nd, Sm, Eu, Gd, Yb, Lu, and Zr. The sputtering target for a magnetic recording medium according to any one of claims 6 to 9, characterized by the above.