JP2009132976A - Sputtering target for depositing perpendicular magnetic recording medium film having low relative magnetic permeability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering target for depositing a perpendicular magnetic recording medium film having a low relative magnetic permeability which is used for depositing a magnetic recording film applied to a high density magnetic recording medium in a hard disk, particularly applied to a perpendicular magnetic recording medium, and to provide a method for producing the same. <P>SOLUTION: The sputtering target has a componential composition comprising, by mol, 0.5 to 15% nonmagnetic oxide, 4 to 20% Cr, 5 to 25% Pt and 0.5 to 8% B, and the balance Co with inevitable impurities, and has a structure in which a composite phase 3 in which a part or the whole surface of a Co-Cr-B ternary alloy phase 1 is surrounded by a thin nonmagnetic oxide phase 2 is uniformly dispersed into a B-containing Pt alloy phase matrix 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

Hard disk devices are generally used as external recording devices for computers, digital home appliances, and the like, but with the expansion of needs for handling large amounts of data such as recording of high-quality video images, further improvement in recording density is required. Therefore, in recent years, a perpendicular magnetic recording system that can realize ultra-high density recording has been adopted. As one of the materials applied to the recording layer of the perpendicular magnetic recording type hard disk medium, there is a CoCrPtB—SiO ₂ granular magnetic recording film. This CoCrPtB—SiO ₂ granular magnetic recording film is made of silicon dioxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, B: 0.5 to 8 containing mol%, the balance has a component composition consisting of Co, the CoCrPtB-SiO ₂ granular magnetic The recording film contains silicon dioxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, B: 0.5 to 8 mol%, and the balance: component composition consisting of Co. It is also known to form the film by sputtering using a target having a thickness (see Patent Document 1). The target having the above component composition is typically a Co-based alloy powder prepared by pulverizing a Co-based alloy ingot containing Cr, Pt and B or a Co-based alloy powder containing Cr, Pt and B prepared by rapid solidification. And silicon dioxide powder containing silicon dioxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, B: 0.5 to 8 mol%, and the balance: Co It is also known that the composition is prepared by mixing and mixing so as to have a composition, followed by vacuum hot pressing or hot isostatic pressing. In addition to SiO ₂ , 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 2 and 3).
JP 2004-310910 A JP 2003-36525 A JP 2006-24346 A

However, this conventional sputtering target for forming a magnetic recording medium film is based on a Co-based alloy containing Cr, Pt and B, which are ferromagnetic alloys, and a non-magnetic oxide such as SiO ₂ is uniformly dispersed in this base. Therefore, the proportion of magnetic flux passing through the inside of the target is larger than that of the non-magnetic target, and the amount of 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.
Also, a target with a low leakage magnetic flux density is such that once erosion is formed by 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,
(B) 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 In the sputtering target having a component composition composed of impurities, the structure of the sputtering target is composed of a Co—Cr—B ternary alloy phase, a Pt alloy phase containing B, and a nonmagnetic oxide phase, and the Co—Cr—B 3 A target having a structure in which the surface of the base alloy phase is surrounded by a nonmagnetic oxide phase and the structure is obtained by uniformly dispersing the composite phase in a Pt alloy phase substrate containing B, the relative permeability further decreases.
(B) The composite phase most preferably surrounds the entire surface of the Co—Cr—B ternary alloy phase with the nonmagnetic oxide phase, but the partial surface of the Co—Cr—B ternary alloy phase. Research results have been obtained, such as being effective even when surrounded by a nonmagnetic oxide phase.

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%, B: 0.5 to 8 mol%, balance: Co and inevitable A sputtering target having a component composition composed of impurities, wherein a composite phase is formed in which a part or the entire surface of a Co—Cr—B ternary alloy phase is surrounded by a thin nonmagnetic oxide phase. The present invention is characterized by a sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability having a structure in which this composite phase is uniformly dispersed in a Pt alloy phase substrate containing B.

Generally, SiO ₂ , TiO, Cr ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , MgO, ThO ₂ , as nonmagnetic oxides in a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability It is already known to use any one of ZrO ₂ , CeO ₂ , and Y ₂ O ₃ , and nonmagnetic oxidation in the sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability described in the above (1) As the product, any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide is used.

Therefore, the present invention
(2) The nonmagnetic oxide phase according to (1), wherein the nonmagnetic oxide phase is any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. It is characterized by a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability.

In order to produce the sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to (1) and (2) of the present invention, a part of Co—Cr—B ternary alloy powder as a raw material powder or A composite powder having a nonmagnetic oxide layer coated on the entire surface is prepared, and further Pt powder is prepared as a raw material powder. %, Pt: 5 to 25 mol%, B: 0.5 to 8 mol%, and the balance: a component composition consisting of Co and inevitable impurities, mixed, and the resulting mixed powder was added. It is produced by pressure sintering. When a composite powder in which a non-magnetic oxide layer is coated on part or all of the Co—Cr—B ternary alloy powder as a raw material powder is mixed with Pt powder and sintered under pressure, the Co—Cr—B ternary is obtained. Part of B contained in the system alloy powder moves into the Pt phase base material to generate a Pt alloy phase base material containing B, and the target structure described in the above (1) and (2) is obtained.
Therefore, the present invention
(3) A composite powder in which a part or all of the Co—Cr—B ternary alloy powder is surrounded by a nonmagnetic oxide layer is prepared, and Pt powder is added to this composite powder as a nonmagnetic oxide: 0.5 to 15 mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, B: 0.5 to 8 mol%, balance: blended so as to have a component composition consisting of Co and inevitable impurities Thus, a mixed powder is produced, and the method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability by pressure-sintering the obtained mixed powder is characterized.

A nonmagnetic oxide layer on a part or all of the surface of the Co-Cr-B ternary alloy powder used as a raw material powder for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability according to the present invention Can be produced by forming a thin non-magnetic oxide layer on the surface of the Co—Cr—B ternary alloy powder by a method such as physical vapor deposition, chemical vapor deposition, sputtering, or chemical plating. . Further, the Co—Cr—B ternary alloy powder and a nonmagnetic oxide powder having a particle size much smaller than the particle size of the Co—Cr—B ternary alloy powder are mixed and stirred to obtain a Co— Non-magnetic oxidation comprising a non-magnetic oxide powder deposited on the surface of a part or all of the Co-Cr-B ternary alloy powder by adhering non-magnetic oxide powder to the surface of the Cr-B ternary alloy powder. The composite powder can be produced by forming a physical layer.

The nonmagnetic oxide layer constituting the composite powder used as the raw material powder in the manufacturing method of the sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability of the present invention includes silicon dioxide, tantalum oxide, titanium oxide, aluminum oxide, One of magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. The pressure sintering performed in the method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to the present invention is preferably a vacuum hot press or a hot isostatic press.
Therefore, the present invention
(4) The ratio according to (3), wherein the nonmagnetic oxide is any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. A method of manufacturing a sputtering target for forming a perpendicular magnetic recording medium film having a low magnetic permeability,
(5) The method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to (3), wherein the pressure sintering is a vacuum hot press or a hot isostatic press. is there.

Furthermore, the composite powder used in the method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability according to the present invention is novel as a raw material powder, and the present invention also includes the composite powder. The composite powder used in the production method described in (3) is effective even when a composite powder in which a part of the surface of the Co—Cr—B ternary alloy powder is coated with a nonmagnetic oxide layer is used. However, it is most preferable to use a composite powder in which the entire surface of the Co—Cr—B ternary alloy powder is coated with a nonmagnetic oxide layer. Therefore, the present invention
(6) To manufacture a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability, comprising a composite powder in which a part or all of the Co—Cr—B ternary alloy powder is coated with a nonmagnetic oxide layer. Raw material powder,
(7) The ratio according to (6), wherein the nonmagnetic oxide is any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. It is characterized by a raw material powder for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low magnetic permeability.

The Co—Cr—B ternary alloy powder preferably contains Cr: 4.2 to 33.3 atomic%, B: 0.5 to 15 atomic%, and the balance is composed of Co. A composite powder in which a part or all of the Co—Cr—B ternary alloy powder having such a component composition is coated with a nonmagnetic oxide layer is used as a raw material powder. This composite powder will be described based on the cross-sectional explanatory view of FIG. The composite powder 5 used as the raw material powder has a structure in which the entire surface of the Co—Cr—B ternary alloy powder 6 is covered with a nonmagnetic oxide layer 7 as shown in the sectional view of FIG. have. Most preferably, the nonmagnetic oxide layer 7 covers the entire surface of the Co—Cr—B ternary alloy powder 6, but as shown in the cross-sectional view of FIG. Even if a part of the surface of the B ternary alloy powder 6 is coated, it is effective. The Co—Cr—B ternary alloy powder 6 has a spherical shape as shown in FIG. 3 when manufactured by the atomizing method, but does not have a spherical shape as shown in FIG. 3 when it is a pulverized powder. .
When a composite powder having such a structure is mixed with Pt powder and sintered under pressure, a part of the B component contained in the Co—Cr—B ternary alloy powder moves to the Pt powder side and a Pt alloy phase containing B is contained. A ratio of the present invention having a structure in which a composite phase in which a base is formed and a composite phase in which a Co—Cr—B ternary alloy phase is coated with a nonmagnetic oxide phase is uniformly dispersed in a Pt alloy phase base containing B A sputtering target for forming a perpendicular magnetic recording medium film having a low magnetic permeability is produced.

  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.

Example 1
Co—Cr—B ternary alloy containing Cr: 26.3 atomic%, B: 1.3 atomic% as a raw material powder, the balance being a component composition consisting of Co and inevitable impurities, and an average particle size: 45 μm A gas atomized powder is prepared, and an SiO ₂ powder having an average particle diameter of 3 μm is prepared as a nonmagnetic oxide powder. The Co—Cr—B ternary alloy atomized powder and the SiO ₂ powder are charged into a ball mill, the atmosphere of the inner to prepare a composite powder SiO ₂ powder is adhered by laminating the Co-Cr-B ternary alloy atomized powder surface by rotating 20 hours while maintaining the Ar gas atmosphere. Pt powder having an average particle diameter of 20 μm is obtained with respect to the obtained composite powder in terms of mol%: Cr: 20.0%, Pt: 17.0%, B: 1.0%, SiO ₂ : 7.0%. And containing the remainder so as to have a component composition consisting of Co and inevitable impurities, charging the resulting blended powder into a ball mill, and rotating for 3 hours while maintaining the atmosphere in the ball mill in an Ar gas atmosphere A mixed powder was prepared. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 750 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.
By cutting the plate-like hot press body, the target 1 of the present invention having a diameter of 152.4 mm and a thickness of 5 mm is produced, and the target 1 of the present invention is further cut, and the cut surface is electronically cut. When observed by the surface analysis method of a wire microprobe analyzer (EPMA), a Pt alloy phase containing B, a SiO ₂ phase and a Co—Cr—B ternary alloy phase are found, and a Co—Cr—B ternary system A structure in which the composite phase in which the SiO ₂ phase is surrounded around the alloy phase is uniformly dispersed in the Pt alloy phase matrix containing B was observed.
Further, the maximum relative magnetic permeability in the in-plane direction of the target 1 of the present invention was measured, and the results are shown in Table 1.

Conventional example 1
Co powder, Cr powder, Pt powder, B powder and SiO ₂ powder were prepared, and these powders were mol% in Cr: 20.0%, Pt: 17.0%, B: 1.0%, SiO ₂ : 7 0.0%, with the balance being a component composition consisting of Co and unavoidable impurities, the resulting blended powder was charged into a ball mill, the atmosphere in the ball mill was maintained in an Ar gas atmosphere, The mixture was rotated for 20 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: 750 ° 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 dimensions of diameter: 152.4 mm and thickness: 5 mm is produced, and further, this conventional target 1 is cut, and the cut surface is cut into an electron micro beam. When observed by a surface analysis method using a probe analyzer (EPMA), a structure in which SiO ₂ particles were uniformly dispersed in the Co—Cr—Pt—B alloy phase was observed. Further, the maximum relative magnetic permeability in the target in-plane direction of this conventional target 1 was measured, and the result is shown in Table 1.

Example 2
Co—Cr—B ternary alloy containing Cr: 21.1 atomic% and B: 2.6 atomic% as raw material powder, the balance being a component composition consisting of Co and inevitable impurities, and an average particle size: 62 μm Atomized powder is prepared. Further, a TiO ₂ powder having an average particle diameter of 2 μm is prepared as a nonmagnetic oxide powder, and the Co—Cr—B ternary alloy atomized powder and TiO ₂ powder are charged into a ball mill. By rotating the inner atmosphere in an Ar gas atmosphere for 20 hours, a composite powder was prepared in which TiO ₂ powder was laminated and adhered to the surface of the Co—Cr—B ternary alloy atomized powder. The obtained composite powder contains Pt powder having an average particle diameter of 20 μm in mol% of Cr: 16.0%, Pt: 15.0%, B: 2.0%, TiO ₂ : 9.0% Then, the balance is blended so as to have a component composition consisting of Co and inevitable impurities, the obtained blended powder is charged into a ball mill, and the mixed powder is rotated for 3 hours while maintaining the atmosphere in the ball mill in an Ar gas atmosphere. Was made. 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: 850 ° 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 is produced, and the target 2 of the present invention is further cut. When observed by the surface analysis method of a wire microprobe analyzer (EPMA), a Pt alloy phase containing B, a TiO ₂ phase, and a Co—Cr—B ternary alloy phase are observed, and a Co—Cr—B ternary system A structure in which the composite phase in which the TiO ₂ phase surrounds the alloy phase was uniformly dispersed in the Pt alloy phase matrix containing B was observed.
FIG. 1 shows a structure photograph when observed with the EPMA. Further, the drawing at this time is shown in FIG. 2 to explain the organization photograph of FIG. As shown in FIGS. 1 and 2, the target 2 of the present invention includes a composite phase 3 in which a Co—Cr—B ternary alloy phase 1 is surrounded by a TiO ₂ phase 2 that is a nonmagnetic oxide phase. However, it turns out that it has the structure | tissue uniformly disperse | distributed in the B containing Pt alloy phase base material 4. FIG.
Furthermore, the maximum relative magnetic permeability in the in-plane direction of the target 2 of the present invention was measured, and the results are shown in Table 1.

Conventional example 2
Co powder, Cr powder, Pt powder, B powder and TiO ₂ powder, in mol%, Cr: 16.0%, Pt: 15.0%, B: 2.0%, TiO ₂ : 9.0% Then, the balance is blended so as to have a component composition consisting of Co and inevitable impurities, the obtained blended powder is charged into a ball mill, the atmosphere in the ball mill is maintained in an Ar gas atmosphere, the ball mill is rotated for 20 hours, A mixed powder was prepared. 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: 850 ° C., pressure: 35 MPa, and 3 hours.
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 a surface analysis method of an electron beam microprobe analyzer (EPMA), TiO ₂ particles were uniformly 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 result is shown in Table 1.

Example 3
Co—Cr—B ternary alloy containing Cr: 16.3 atomic% and B: 5.0 atomic% as raw material powder, the balance being a component composition consisting of Co and inevitable impurities, and an average particle size: 54 μm Atomized powder is prepared, and Ta ₂ O ₅ powder having an average particle size of 1.5 μm is prepared as a nonmagnetic oxide powder. The Co—Cr—B ternary alloy atomized powder and Ta ₂ O ₅ powder are ball milled. The Ta ₂ O ₅ powder is laminated and adhered to the surface of the Co—Cr—B ternary alloy atomized powder by rotating for 20 hours while maintaining the atmosphere in the ball mill in an Ar gas atmosphere. A composite powder was produced. Pt powder having an average particle diameter of 20 μm is Cr: 13.0%, Pt: 17.0%, B: 4.0%, Ta ₂ O ₅ : 3.0% with respect to the obtained composite powder. And the balance is a component composition consisting of Co and inevitable impurities, the obtained blended powder is charged into a ball mill, and rotated for 3 hours while maintaining the atmosphere in the ball mill in an Ar gas atmosphere, A mixed powder was prepared. The obtained mixed powder was filled in a vacuum hot press apparatus and vacuum hot pressed in a vacuum atmosphere under conditions of temperature: 900 ° C., pressure: 35 MPa, and 3 hours to prepare a plate-like hot press body.

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, and the target 3 of the present invention was further cut. When observed by the surface analysis method of a wire microprobe analyzer (EPMA), a Pt alloy phase containing B, a Ta ₂ O ₅ phase, and a Co—Cr—B ternary alloy phase are observed, and Co—Cr—B A structure in which the composite phase in which the Ta ₂ O ₅ phase surrounds the ternary alloy phase is uniformly dispersed in the Pt alloy phase matrix containing B was observed.
Further, the maximum relative magnetic permeability in the target in-plane direction was measured for the target 3 of the present invention, and the results are shown in Table 1.

Conventional example 3
Co powder, Cr powder, Pt powder, the B powders and _Ta 2 _{O 5} powder, Cr in mol%: 13.0%, Pt: 17.0 %, B: 4.0%, Ta 2 O 5: 3. It is blended so that it contains 0% and the balance is a component composition consisting of Co and inevitable impurities. The resulting blended powder is charged into a ball mill, the atmosphere in the ball mill is maintained in an Ar gas atmosphere, The mixture was rotated for a time 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, 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 a surface analysis method of an electron beam microprobe analyzer (EPMA), Ta ₂ O ₅ particles were uniformly dispersed in the Co—Cr—Pt—B alloy phase. Organization was seen. Further, the maximum relative permeability in the target in-plane direction of this conventional target 3 was measured, and the result is shown in Table 1.

Example 4
Co—Cr—B ternary alloy containing Cr: 13.5 atomic% and B: 8.1 atomic% as raw material powder, the balance being a component composition consisting of Co and inevitable impurities, and an average particle size: 38 μm prepared atomized powder, further the average particle size as the non-magnetic oxide powder: prepared _Al 2 _{O 3} powder of 1 [mu] m, instrumentation the Co-Cr-B ternary alloy atomized powder and _Al 2 _{O 3} powder in a ball mill The composite powder in which Al ₂ O ₃ powder is laminated and adhered to the surface of the Co—Cr—B ternary alloy atomized powder by rotating for 20 hours while keeping the atmosphere in the ball mill in an Ar gas atmosphere. Was made. Pt powder having an average particle diameter of 20 μm is Cr: 10.0%, Pt: 14.0%, B: 6.0%, Al ₂ O ₃ : 12.0% with respect to the obtained composite powder. And the balance is a component composition consisting of Co and inevitable impurities, the obtained blended powder is charged into a ball mill, and rotated for 3 hours while maintaining the atmosphere in the ball mill in an Ar gas atmosphere, A mixed powder was prepared. The obtained mixed powder was filled into 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: 950 ° 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 cutting the invention target 4, was observed with the cut surface in the surface analysis of the electron beam microprobe analyzer (EPMA), Pt alloy phase containing B, _Al 2 _{O 3} phase and Co-Cr-B A structure in which a ternary alloy phase is observed and a composite phase in which an Al ₂ O ₃ phase surrounds the Co—Cr—B ternary alloy phase is uniformly dispersed in a Pt alloy phase matrix containing B It was observed.
Further, the maximum relative magnetic permeability in the target in-plane direction was measured for the target 4 of the present invention, and the results are shown in Table 1.

Conventional example 4
Co powder, Cr powder, Pt powder, B powder and Al ₂ O ₃ powder were mixed in mol% of Cr: 10.0%, Pt: 14.0%, B: 6.0%, Al ₂ O ₃ : 12. The resulting blended powder was charged into a ball mill, the atmosphere in the ball mill was maintained in an Ar gas atmosphere, and the ball mill was mixed with 20%. The mixture was rotated for a time to produce a mixed powder. The obtained mixed powder was filled into 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: 950 ° C., pressure: 35 MPa, and 3 hours.
By cutting this plate-like hot press body, a conventional target 4 having a diameter of 152.4 mm and a thickness of 5 mm is produced, and this conventional target 4 is cut, and the cut surface is cut into an electron beam micro was observed with a surface analysis method of the probe analyzer (EPMA), _{tissue Al} 2 _{O 3} particles are uniformly dispersed was observed in the Co-Cr-Pt-B alloy phase. Further, the maximum relative permeability in the target in-plane direction of this conventional target 4 was measured, and the result is shown in Table 1.

  From the results shown in Table 1, the target 1 of the present invention in which the composite phase is uniformly dispersed in the Pt alloy phase matrix containing B is relatively transparent compared to the conventional target 1 even though the component composition is the same. Since the magnetic susceptibility is small, it can be seen that the leakage magnetic flux density is large during sputtering, and therefore the target 1 of the present invention can be sputtered more efficiently than the conventional target 1. Similarly, when the inventive targets 2 to 4 and the conventional targets 2 to 4 are respectively compared, the inventive targets 2 to 4 are more transparent than the conventional targets 2 to 4 due to the difference in the structure even though the component composition is the same. From the fact that the magnetic susceptibility is small, it can be seen that the leakage magnetic flux density is large at the time of sputtering, so that the present invention targets 2 to 4 can be sputtered more efficiently than the conventional targets 2 to 4, respectively.

4 is a structure photograph of the target 2 of the present invention produced in Example 2 by EPMA. 6 is a drawing of the structure of the target 2 of the present invention produced in Example 2. FIG. It is a cross-sectional explanatory drawing of the composite powder used in order to produce the sputtering target for perpendicular magnetic recording medium film formation with a low relative magnetic permeability of this invention.

Explanation of symbols

1: Co—Cr—B ternary alloy phase 2: TiO ₂ phase 3: composite phase 4: Pt alloy phase substrate containing B 5: composite powder 6: Co—Cr—B ternary alloy powder 7: non-magnetic Oxide layer

Claims (7)

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,
In this sputtering target, a composite phase in which a part or all of the Co—Cr—B ternary alloy phase is surrounded by a thin nonmagnetic oxide phase is uniformly dispersed in a Pt alloy phase matrix containing B. A sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability, characterized by having a structure having 2. The nonmagnetic oxide phase is made of any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. Sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability. A composite powder in which a part or all of the Co—Cr—B ternary alloy powder is coated with a nonmagnetic oxide layer is prepared, and Pt powder is added to this composite powder as a nonmagnetic oxide: 0.5 to 15 A mixed powder was obtained by mixing and mixing so as to have a component composition comprising mol%, Cr: 4 to 20 mol%, Pt: 5 to 25 mol%, and the balance: Co and inevitable impurities. A method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability, wherein the mixed powder is subjected to pressure sintering. 4. The nonmagnetic oxide is any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. A method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability. 4. The method for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability according to claim 3, wherein the pressure sintering is a vacuum hot press or a hot isostatic press. A sputtering target for forming a perpendicular magnetic recording medium film having a low relative permeability, comprising a composite powder in which a non-magnetic oxide layer is coated on a part or all of a Co-Cr-B ternary alloy powder. Raw material powder to do. 7. The nonmagnetic oxide layer is made of any one of silicon oxide, titanium oxide, tantalum oxide, aluminum oxide, magnesium oxide, thorium oxide, zirconium oxide, cerium oxide, and yttrium oxide. Raw material powder for producing a sputtering target for forming a perpendicular magnetic recording medium film having a low relative magnetic permeability.

Images