JP2009001860A - Sputtering target for use in forming film of perpendicular magnetic recording medium having low relative magnetic permeability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering target to be used in forming a film of a perpendicular magnetic recording medium having low relative magnetic permeability, which is used for forming a magnetic recording film to be applied to a high-density magnetic recording medium of a hard disk, and particularly for forming a magnetic recording film to be applied to the perpendicular magnetic recording medium. <P>SOLUTION: The sputtering target has a component composition comprising 0.5 to 15 mol% non-magnetic oxide, 4 to 20 mol% Cr, 5 to 25 mol% Pt, further 0.5 to 8 mol% B as needed, and the balance Co with unavoidable impurities; and has such a structure that Co-Cr binary alloy phases are uniformly dispersed in a matrix. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability for forming a magnetic recording film applied to a high-density magnetic recording medium of a hard disk, particularly a magnetic recording film applied to a perpendicular magnetic recording medium. It is about.

Hard disk devices are generally used as external recording devices such as computers and digital home appliances, and further improvement in recording density is required. Therefore, in recent years, a perpendicular magnetic recording system that can realize ultra-high-density recording has attracted attention. Unlike the conventional in-plane recording system, this perpendicular magnetic recording system is said to have a stable recording magnetization as the density increases in principle, and has already been put into practical use. A CoCrPt—SiO ₂ granular magnetic recording film has been proposed as a promising candidate for a material to be applied to the recording layer of the perpendicular magnetic recording type hard disk medium, and the CoCrPt—SiO ₂ granular magnetic recording film is a Co containing Cr and Pt. It is known to produce by a magnetron sputtering method using a sputtering target having a mixed phase of a base sintered alloy phase and a silicon dioxide phase (see Non-Patent Document 1).
This sputtering target usually contains silicon dioxide powder, Cr powder, Pt powder and Co powder, silicon dioxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%. The remainder: It is known to be prepared by mixing and mixing so as to have a composition consisting of Co, and then vacuum hot pressing or hot isostatic pressing, and in addition, a commercially available Co base containing Cr and Pt. Co-based alloy powder and silicon dioxide powder containing Cr and Pt prepared by alloy solidification or rapid solidification, silicon dioxide: 0.5-15 mol%, Cr: 4-20 mol%, Pt: 5-25 mol% It is known that it is prepared by mixing and mixing so as to have a composition comprising Co: balance: Co, and then vacuum hot pressing or hot isostatic pressing. (See Patent Document 1, Patent Document 2, etc.).
Further, silicon dioxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, and the balance: Co: B: 0.5 to 8 mol% The target of the composition to contain is also known (refer patent document 5). In addition to silicon dioxide, nonmagnetic oxidation such as TiO, Cr ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , BeO ₂ , MgO, ThO ₂ , ZrO ₂ , CeO ₂ , Y ₂ O _3, etc. It is known that products can be used (see Patent Documents 3 and 4).
“Fuji Times” Vol. 75No. 3 2002 (pages 169-172) Japanese Patent Laid-Open No. 2001-236643 JP 2004-339586 A JP 2003-36525 A JP 2006-24346 A JP 2004-310910 A

However, this conventional sputtering target for forming a magnetic recording medium film is based on a Co-based alloy containing Cr and Pt, which are ferromagnetic alloys, and non-magnetic oxides such as SiO ₂ are uniformly dispersed in the substrate. Since it has a structure, the proportion of magnetic flux passing through the inside of the target is larger than that of the non-magnetic target, and the magnetic flux leaking over the target is extremely small. This is for magnetron sputtering, which has a magnetic circuit placed under the target and stabilizes the discharge by increasing the ionization efficiency of the noble gas by utilizing the magnetic flux leaking over the target, thereby improving the deposition rate. It becomes a big problem. In other words, if magnetron sputtering is performed using a target having a low leakage magnetic flux density (ie, a target having a high relative permeability) with a small amount of magnetic flux leaking over the target, the deposition rate is extremely high even if the discharge is not stable or can be discharged. This is because it causes problems such as slowness.
As one of means for solving this problem, a method is adopted in which the thickness of the target is reduced so that the magnetic flux easily escapes over the target. However, if the target is made thin, the replacement frequency of the target becomes frequent, so that the film formation efficiency is deteriorated, which is not preferable in terms of cost.
In addition, a target with low leakage magnetic flux density is once the erosion is formed by performing magnetron sputtering, magnetic flux leaks intensively from the erosion part, and only that part is intensively sputtered. It tends to cause problems such as a decrease in utilization efficiency, a change in deposition rate over time, a variation in film thickness within the substrate surface, and a large amount of redeposition film deposited on the target.

Therefore, the present inventors have studied to obtain a sputtering target having a low relative permeability without reducing the thickness of the target. as a result,
(A) Non-magnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, and the remainder: a sputtering target having a component composition consisting of Co and inevitable impurities A target having a structure in which the contained ferromagnetic component Co is dispersed so as to be a binary alloy phase with Cr, and Pt and a nonmagnetic oxide are dispersed as a Pt phase and a nonmagnetic oxide phase has a specific permeability. Magnetic susceptibility decreases,
(B) Nonmagnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, further B: 0.5 to 8 mol%, the balance : Co and ferromagnetic component contained in a sputtering target having a component composition composed of Co and inevitable impurities are dispersed so as to form a binary alloy phase with Cr, and further Pt, nonmagnetic oxide and B are mixed with Pt and B. It was found that a target having a structure dispersed as an alloy phase and a nonmagnetic oxide phase has a lower relative permeability.

This invention was made based on these findings,
(1) Nonmagnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, a sputtering target having a component composition composed of Co and inevitable impurities The sputtering target has a structure in which a Co—Cr binary alloy phase, a Pt phase and a nonmagnetic oxide phase are uniformly dispersed, and has a low relative permeability perpendicular magnetic recording medium film forming sputtering target,
(2) Nonmagnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, B: 0.5 to 8 mol%, balance: Co and inevitable A sputtering target having a component composition consisting of impurities, the sputtering target having a structure in which a Co—Cr binary alloy phase, an alloy phase of Pt and B, and a nonmagnetic oxide phase are uniformly dispersed in the substrate. It is characterized by a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability.

In the Co—Cr binary alloy phase of the sputtering target described in (1), the Pt of the base material diffuses and penetrates into the outer periphery of the Co—Cr binary alloy phase during hot pressing, and the Co—Cr binary alloy phase May be covered with a diffusion layer made of Co, Cr and Pt. This diffusion layer is preferably absent, but if this diffusion layer is extremely thin, it does not significantly affect the characteristics, and Co, Cr is formed on the outer periphery of the Co—Cr binary alloy phase of the sputtering target described in (1). A case where a diffusion layer composed of Pt and Pt is formed is also included in the present invention. Therefore, the present invention
(3) The sputtering for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to (1), wherein the Co—Cr binary alloy phase is covered with a diffusion layer made of Co, Cr, and Pt. The target has characteristics.

In the Co—Cr binary alloy phase of the sputtering target described in (2) above, Pt and B of the base material diffuse and penetrate into the outer periphery of the Co—Cr binary alloy phase during hot pressing, and the Co—Cr binary system The outer periphery of the alloy phase may be covered with a diffusion layer composed of Co, Cr, Pt and B. It is preferable that this diffusion layer is not present. However, if this diffusion layer is extremely thin, it does not have a large effect on the characteristics, and Co, Cr is formed on the outer periphery of the Co—Cr binary alloy phase of the sputtering target described in (2). The case where a diffusion layer composed of Pt and B is formed is also included in the present invention. Therefore, the present invention
(4) The Co—Cr binary alloy phase is covered with a diffusion layer made of Co, Cr, Pt, and B. The low-permeability perpendicular magnetic recording medium film formation according to (2) above The sputtering target has a feature.

The nonmagnetic oxide included in the sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to the present invention includes silicon dioxide, tantalum oxide, titanium oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, and cerium oxide. And yttrium oxide, which are already known.

In order to manufacture the sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability according to the present invention, a Co—Cr binary alloy powder, a Pt powder, and a nonmagnetic oxide powder are prepared as raw powders, and further required. B powder is prepared accordingly, and these raw material powders contain nonmagnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, and B: It contains 0.5 to 8 mol%, and is mixed and mixed so as to have a component composition consisting of the balance: Co and inevitable impurities, and the obtained mixed powder is hot pressed at a temperature lower than usual (700 to 1050 ° C.). This prevents Co and Cr contained in the Co—Cr binary alloy powder from diffusing into the substrate, and further prevents Pt of the substrate from diffusing and penetrating into the Co—Cr binary alloy phase. preferable.

The Co—Cr binary alloy powder preferably contains Cr: 4.2 to 33.3 mol%, and the balance is preferably composed of Co. Therefore, the perpendicular magnetic field with low relative permeability of the present invention is preferable. The Co—Cr binary alloy phase dispersed in the substrate of the sputtering target for forming the recording medium film also contains Cr: 4.2 to 33.3 mol%, and the balance is composed of Co. . The component composition of the Co—Cr binary alloy powder and the component composition of the Co—Cr binary alloy phase uniformly dispersed in the substrate are the sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to the present invention. It is determined by the component composition.

  When the sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to the present invention is used, magnetron sputtering can be performed efficiently, which can greatly contribute to the development of industries such as computers and digital home appliances.

As raw material powders, the average particle size having the composition shown in Table 1: Co-Cr binary alloy powders A to I of 20 μm, the average particle size: Pt powder of 25 μm, the average particle size: B powder of 5 μm, the average Co powder having a particle size of 5 μm and Cr powder having an average particle size of 15 μm are prepared. Further, as nonmagnetic oxide powders, the average particle size is 3 μm of SiO ₂ powder, TiO ₂ powder, Ta ₂ O ₅ powder and Al. ₂ O ₃ powder was prepared.

Example 1
Co-Cr binary alloy powder A, Pt powder and SiO ₂ powder shown in Table 1 contain Cr: 10.8%, Pt: 15.3%, SiO ₂ : 10.0%, the balance being Compounding so as to have a component composition consisting of Co and inevitable impurities, the obtained blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, and the atmosphere in this container is replaced with an Ar gas atmosphere, Thereafter, the container was sealed. This container was rotated with a ball mill for 12 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
The target 1 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced by cutting the plate-like hot press body. Further, when the target 1 of the present invention was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, a Pt phase, a SiO ₂ phase and a Co—Cr binary alloy phase were observed. A diffusion layer was observed around the Co—Cr binary alloy phase.
The maximum relative magnetic permeability in the target in-plane direction was measured for the target 1 of the present invention, and the results are shown in Table 2.

Conventional example 1
The previously prepared Co powder, Cr powder, Pt powder and SiO ₂ powder contain Cr: 10.8%, Pt: 15.3%, SiO ₂ : 10.0%, and the remainder from Co and inevitable impurities The resulting blended powder is put into a 10-liter container together with zirconia balls as a grinding medium, the atmosphere in the container is replaced with an Ar gas atmosphere, and then the container is sealed. did. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, a conventional target 1 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further, when this conventional target 1 was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, a structure in which SiO ₂ particles were uniformly dispersed in the Co—Cr—Pt alloy phase. It was observed. The maximum relative permeability in the target in-plane direction of this conventional target 1 was measured, and the results are shown in Table 2.

Example 2
Co-Cr binary alloy powder B, Pt powder, SiO ₂ powder and B powder shown in Table 1 are Cr: 10.8%, Pt: 15.3%, SiO ₂ : 10.0%, B: 1.0% is contained and the remainder is blended so as to have a component composition consisting of Co and inevitable impurities, and the obtained blended powder is put into a 10 liter container together with zirconia balls serving as a grinding medium. The atmosphere was replaced in an Ar gas atmosphere, and then the container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 2 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further, the target 2 of the present invention was cut, and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method. As a result, an alloy phase of Pt and B, a SiO ₂ phase, and a Co—Cr binary alloy A structure in which the phases were uniformly dispersed was observed, and a diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the target in-plane direction was measured for the target 2 of the present invention, and the results are shown in Table 2.

Conventional example 2
Co powder, Cr powder, Pt powder, SiO ₂ powder and B powder prepared earlier are Cr: 10.8%, Pt: 15.3%, SiO ₂ : 10.0%, B: 1.0%. It is blended so that the balance is a component composition comprising Co and inevitable impurities, and the resulting blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, and the atmosphere in the container is an Ar gas atmosphere Replaced in, then sealed the container. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, a conventional target 2 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Furthermore, when this conventional target 2 was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, the SiO ₂ particle phase was dispersed in the Co—Cr—Pt—B alloy phase. Some organizations were seen. The maximum relative permeability in the target in-plane direction of this conventional target 2 was measured, and the results are shown in Table 2.

Example 3
Co-Cr binary alloy powder C, Pt powder and TiO ₂ powder shown in Table 1 contain Cr: 9.9%, Pt: 13.5%, TiO ₂ : 10.0%, the balance being Compounding so as to have a component composition consisting of Co and inevitable impurities, the obtained blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, and the atmosphere in this container is replaced with an Ar gas atmosphere, Thereafter, the container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 3 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further, when the target 3 of the present invention was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, a Pt phase, a TiO ₂ phase and a Co—Cr binary alloy phase were found. A diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the in-plane direction of the target 3 of the present invention was measured, and the results are shown in Table 2.

Conventional example 3
Co powder, Cr powder, Pt powder and TiO ₂ powder prepared previously contain Cr: 9.9%, Pt: 13.5%, TiO ₂ : 10.0%, and the balance from Co and inevitable impurities The resulting blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, the atmosphere in the container is replaced with an Ar gas atmosphere, and then the container is sealed. did. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, a conventional target 3 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further, when this conventional target 3 was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, a structure in which the TiO ₂ particle phase was dispersed in the Co—Cr—Pt alloy phase. It was observed. The maximum relative permeability in the target in-plane direction of this conventional target 3 was measured, and the results are shown in Table 2.

Example 4
Co—Cr binary alloy powder D, Pt powder, TiO ₂ powder and B powder shown in Table 1 were changed to Cr: 13.4%, Pt: 15.3%, TiO ₂ : 10.0%, B: It is blended so as to have a component composition comprising 4.3% and the balance consisting of Co and inevitable impurities, and the obtained blended powder is put into a 10 liter container together with zirconia balls serving as a grinding medium. The atmosphere was replaced in an Ar gas atmosphere, and then the container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 4 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further, the target 4 of the present invention was cut, and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method. As a result, an alloy phase of Pt and B, a TiO ₂ phase and a Co—Cr binary alloy were obtained. A structure in which the phases were uniformly dispersed was observed, and a diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the target in-plane direction of this target 4 of the present invention was measured, and the results are shown in Table 2.

Conventional example 4
Co powder, Cr powder, Pt powder, TiO ₂ powder and B powder prepared earlier are Cr: 13.4%, Pt: 15.3%, TiO ₂ : 10.0%, B: 4.3% It is blended so that the balance is a component composition comprising Co and inevitable impurities, and the resulting blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, and the atmosphere in the container is an Ar gas atmosphere Replaced in, then sealed the container. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, the conventional target 4 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Furthermore, when this conventional target 4 was cut and the cut surface was observed by the surface analysis method of an electron beam microprobe analyzer (EPMA), TiO ₂ was uniformly dispersed in the Co—Cr—Pt—B alloy substrate. Organization was seen. The maximum relative permeability in the target in-plane direction of this conventional target 4 was measured, and the results are shown in Table 2.

Example 5
Co—Cr binary alloy powder E, Pt powder and Ta ₂ O ₅ powder shown in Table 1 contain Cr: 16.0%, Pt: 15.4%, Ta ₂ O ₅ : 5.0% Then, the remainder is blended so as to have a component composition consisting of Co and inevitable impurities, and the obtained blended powder is put into a 10-liter container together with zirconia balls as a grinding medium, and the atmosphere in the container is placed in an Ar gas atmosphere. The container was then sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 5 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further cutting the invention target 5, was observed with the cut surface in the surface analysis of the electron beam microprobe analyzer (EPMA), Pt phase, _Ta 2 _{O 5} phase and Co-Cr binary alloy phase A diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the target in-plane direction of this target 5 of the present invention was measured, and the results are shown in Table 2.

Conventional Example 5
The previously prepared Co powder, Cr powder, Pt powder and Ta ₂ O ₅ powder contain Cr: 16.0%, Pt: 15.4%, Ta ₂ O ₅ : 5.0%, the balance being Co And the resulting blended powder is put into a 10-liter container together with zirconia balls as a grinding medium, and the atmosphere in the container is replaced with an Ar gas atmosphere. The container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, a conventional target 5 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Furthermore, when this conventional target 5 was cut and the cut surface was observed by a surface analysis method of an electron beam microprobe analyzer (EPMA), Ta ₂ O ₅ particle phase was dispersed in the Co—Cr—Pt alloy phase. Some organizations were seen. The maximum relative magnetic permeability in the target in-plane direction of this conventional target 5 was measured, and the results are shown in Table 2.

Example 6
Co—Cr binary alloy powder F, Pt powder, Ta ₂ O ₅ powder and B powder shown in Table 1 were mixed with Cr: 20.5%, Pt: 15.3%, Ta ₂ O ₅ : 4.0. %, B: 3.8%, with the balance being a component composition consisting of Co and inevitable impurities, the resulting blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, The atmosphere in the container was replaced with an Ar gas atmosphere, and then the container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 6 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further cutting the invention target 6, observation of the cut surface by a surface analysis of an electron beam microprobe analyzer (EPMA), an alloy phase of Pt and B, _Ta 2 _{O 5} phase and Co-Cr two yuan An alloy phase was observed, and a diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the target in-plane direction of this target 6 of the present invention was measured, and the results are shown in Table 2.

Conventional Example 6
Co powder prepared in advance, Cr powder, Pt powder, a _Ta 2 _{O 5} powder and B powder, Cr: 20.5%, Pt: 15.3%, Ta 2 O 5: 4.0%, B: 3 .8%, with the balance being a component composition consisting of Co and unavoidable impurities, the resulting blended powder is put into a 10-liter container together with zirconia balls as a grinding medium, and the atmosphere in this container Was replaced in an Ar gas atmosphere, and then the vessel was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, a conventional target 6 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Furthermore, when this conventional target 6 was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, the Ta ₂ O ₅ particle phase was uniform in the Co—Cr—Pt—B alloy phase. A distributed organization was seen. The maximum relative permeability in the target in-plane direction of this conventional target 6 was measured, and the results are shown in Table 2.

Example 7
Co-Cr binary alloy powder G, Pt powder and Al ₂ O ₃ powder shown in Table 1 contain Cr: 10.7%, Pt: 14.7%, Al ₂ O ₃ : 6.0% Then, the remainder is blended so as to have a component composition consisting of Co and inevitable impurities, and the obtained blended powder is put into a 10-liter container together with zirconia balls as a grinding medium, and the atmosphere in the container is placed in an Ar gas atmosphere. The container was then sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 7 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further, the target 7 of the present invention was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method. As a result, a Pt phase, an Al ₂ O ₃ phase, and a Co—Cr binary alloy phase were found. A diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the target in-plane direction of this target 7 of the present invention was measured, and the results are shown in Table 2.

Conventional Example 7
The previously prepared Co powder, Cr powder, Pt powder and Al ₂ O ₃ powder contain Cr: 10.7%, Pt: 14.7%, Al ₂ O ₃ : 6.0%, the balance being Co And the resulting blended powder is put into a 10-liter container together with zirconia balls as a grinding medium, and the atmosphere in the container is replaced with an Ar gas atmosphere. The container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting this plate-like hot press body, a conventional target 7 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Furthermore, when this conventional target 7 was cut and the cut surface was observed by an electron beam microprobe analyzer (EPMA) surface analysis method, the Al ₂ O ₃ particle phase was uniformly dispersed in the Co—Cr—Pt alloy phase. The organization that has been seen. The maximum relative permeability in the target in-plane direction of this conventional target 7 was measured, and the results are shown in Table 2.

Example 8
Table 1 shows the Co-Cr binary alloy powder H, Pt powder, _Al 2 _{O 3} powder, the B powder, Cr: 8.5%, Pt: 14.7%, Al 2 O 3: 8.0 %, B: 2.7%, the balance is a component composition consisting of Co and inevitable impurities, the resulting blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, The atmosphere in the container was replaced with an Ar gas atmosphere, and then the container was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus, and a plate-like hot press body was produced by vacuum hot pressing in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, the target 8 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further cutting the invention target 8 Observation of a cut surface by surface analysis of an electron beam microprobe analyzer (EPMA), an alloy phase of Pt and B, _Al 2 _{O 3} phase and Co-Cr two yuan An alloy phase was observed, and a diffusion layer was observed around the Co—Cr binary alloy phase. The maximum relative permeability in the target in-plane direction of this target 8 of the present invention was measured, and the results are shown in Table 2.

Conventional Example 8
Co powder, Cr powder, Pt powder, Al ₂ O ₃ powder, and B powder prepared earlier are Cr: 8.5%, Pt: 14.7%, Al ₂ O ₃ : 8.0%, B: 2. .7%, with the balance being a component composition consisting of Co and inevitable impurities, the resulting blended powder is put into a 10 liter container together with zirconia balls as a grinding medium, and the atmosphere in this container Was replaced in an Ar gas atmosphere, and then the vessel was sealed. This container was rotated with a ball mill for 16 hours to produce a mixed powder. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 1100 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting the plate-like hot press body, a conventional target 8 having a diameter of 152.4 mm and a thickness of 5 mm was produced. Further cutting the conventional target 8, the cut surface was observed by a surface analysis of an electron beam microprobe analyzer (EPMA), Co-Cr- Pt-B Al 2 O 3 grain phase is homogeneous alloy phase A distributed organization was seen. The maximum relative permeability in the target in-plane direction of this conventional target 8 was measured, and the results are shown in Table 2.

  From the results shown in Table 2, the targets 1 to 8 of the present invention in which the Co—Cr binary alloy phase is uniformly dispersed in the substrate have a lower relative permeability than the conventional targets 1 to 8, and thus sputtering is performed. At this time, the leakage magnetic flux density is large. Therefore, it can be seen that the inventive targets 1-8 can be sputtered more efficiently than the conventional targets 1-8.

Claims (4)

Non-magnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, a sputtering target having a component composition consisting of Co: unavoidable impurities: This sputtering target has a structure in which a Co—Cr binary alloy phase, a Pt phase, and a nonmagnetic oxide phase are uniformly dispersed. A sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability. Nonmagnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, B: 0.5 to 8 mol%, balance: Co and inevitable impurities A sputtering target having a component composition, wherein the sputtering target has a structure in which a Co—Cr binary alloy phase, an alloy phase of Pt and B, and a nonmagnetic oxide phase are uniformly dispersed in a substrate. A sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability. 2. The perpendicular magnetic recording medium film having a low relative permeability according to claim 1, wherein the Co-Cr binary alloy phase is covered with a diffusion layer made of Co, Cr and Pt. Sputtering target. 3. The perpendicular magnetic recording medium film having a low relative permeability according to claim 2, wherein the Co-Cr binary alloy phase is covered with a diffusion layer made of Co, Cr, Pt and B. Sputtering target for formation.