阅读说明：本技术 溅射靶用Fe-Pt-氧化物-BN系烧结体 (Fe-Pt-oxide-BN sintered body for sputtering target ) 是由 西浦正纮 山本孝充 黑濑健太 小林弘典 宫下敬史 于 2019-03-18 设计创作，主要内容包括：本发明提供能够抑制溅射时的微粒产生的高密度的溅射靶用Fe-Pt-氧化物-BN系烧结体。一种溅射靶用Fe-Pt-氧化物-BN系烧结体,其中,N相对于B的质量比N/B在1.30±0.1的范围内。(The invention provides a high-density Fe-Pt-oxide-BN sintered body for a sputtering target, which can suppress the generation of fine particles during sputtering. An Fe-Pt-oxide-BN sintered body for a sputtering target, wherein the mass ratio N/B of N to B is in the range of 1.30+ -0.1.)

1. An Fe-Pt-oxide-BN sintered body for a sputtering target, wherein the mass ratio N/B of N to B is in the range of 1.30+ -0.1.

2. The Fe-Pt-oxide-BN sintered body for a sputtering target according to claim 1, wherein the relative density measured by the Archimedes method is 92.0% or more.

3. The Fe-Pt-oxide-BN sintered body for a sputtering target according to claim 1 or 2, wherein Pt is 33 mol% or more and 60 mol% or less, BN and the oxide in total are 5 mol% or more and 40 mol% or less, and the balance is Fe and inevitable impurities.

4. The Fe-Pt-oxide-BN sintered body for a sputtering target according to claim 1 or 2, wherein Pt is 33 mol% or more and 60 mol% or less, BN and an oxide in total are 5 mol% or more and 40 mol% or less, 1 or more selected from Co, Zn, Ge, Rh, Ru and Pd are 1 mol% or more and 15 mol% or less, and the balance is Fe and unavoidable impurities.

5. The Fe-Pt-oxide-BN sintered body for a sputtering target according to claim 1 or 2, wherein Pt is 33 mol% or more and 60 mol% or less, BN and the oxide in total are 5 mol% or more and 40 mol% or less, C is 1 mol% or more and 15 mol% or less, and the balance is Fe and unavoidable impurities.

6. The Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of claims 1 to 5, wherein the oxide is selected from oxides of Si, Ti and Ta.

7. A method for producing the Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of claims 1 to 6, wherein a metal powder, an oxide powder and a BN powder are mixed and sintered at a temperature of 850 ℃ or lower.

8. A method for producing an Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of claims 1 to 6, wherein an FePt alloy powder and an oxide powder are mixed to form a composite oxide alloy powder in which an oxide is finely dispersed in the FePt alloy, then a BN powder is added to the composite oxide alloy powder to form a BN-containing composite oxide alloy powder, and then the BN-containing composite oxide alloy powder is sintered at a temperature of 850 ℃ or lower.

9. A method for producing an Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of claims 1 to 6, wherein an FePt alloy powder and an oxide powder are strongly mixed to form a composite oxide alloy powder in which an oxide is finely dispersed in the FePt alloy, then a BN powder is added to the composite oxide alloy powder and weakly mixed to form a composite oxide alloy powder containing BN, and then the composite oxide alloy powder containing BN is sintered at a temperature of 850 ℃ or lower.

Technical Field

The present invention relates to an Fe-Pt-oxide-BN sintered body for a sputtering target and a method for producing the same.

Background

Since the FePt alloy can have an fct (Ordered Face Centered Tetragonal) structure having high magnetocrystalline anisotropy by heat treatment at a high temperature (for example, 600 ℃. Although the FePt-based magnetic recording medium is formed using a FePt-based sputtering target, the production yield is reduced by fine particles generated during sputtering, and therefore, reduction in generation of fine particles is required.

Various Fe-Pt sputtering targets comprising FePt alloy magnetic phases and nonmagnetic phases present between the magnetic phases have been proposed, and SiO is often used as the nonmagnetic phase₂Etc., BN (boron nitride), C, etc.

For example, patent document 1 (japanese patent No. 5567227) discloses "a sintered body of an Fe — Pt magnetic material characterized by containing hexagonal BN and SiO₂As the nonmagnetic material, Si and O' are present in the region where B or N is present on the cut surface of the sintered body. Specifically, 0.5 to 10 μm inclusive of Fe powder, Pt powder, BN powder and SiO₂The powder was put into a ball mill and stirred and mixed at 300rpm for 2 hours, the mixed powder was sintered at 950 ℃ and 30MPa, and the sintered body was subjected to hot isostatic pressing at 950 ℃ and 150MPa to produce Fe-Pt-SiO with a relative density of 98.3%₂BN sintered body (example 2).

Patent document 2 (japanese patent No. 5913620) discloses "a BN-containing Fe — Pt sintered sputtering target characterized in that the intensity ratio of the X-ray diffraction peak intensity of hexagonal BN (002) plane in a plane horizontal to the sputtering plane to the X-ray diffraction peak intensity of hexagonal BN (002) plane in a cross section perpendicular to the sputtering plane is 2 or more". Specifically, it describes the use of Fe-Pt alloy powder and SiO₂The powder was put into a ball mill, and stirred and mixed at 300rpm for 2 hours to pulverize the powder to give an alloy powder in a plate-like or flake-like form, then a BN powder (flake-like form) was added and mixed using a 100 μm mesh sieve, the mixed powder was sintered at 1100 ℃ and 30MPa, and then the sintered body was subjected to hot isostatic pressing at 1100 ℃ and 150MPa to produce Fe-Pt-SiO having a layered structure of BN oriented in the cross-sectional direction perpendicular to the sputtering surface₂BN sintered body (example 2).

Disclosure of Invention

Problems to be solved by the invention

In the inventions disclosed in patent documents 1 and 2, Fe-Pt-SiO is improved by sintering at a high temperature of 950 ℃ or 1100 ℃ and then hot isostatic pressing₂Density of sintered BN. Since the hot isostatic pressing after sintering increases the number of manufacturing processes and requires an equipment machine for hot isostatic pressing, it is complicated.

The purpose of the present invention is to provide a high-density Fe-Pt-oxide-BN sintered body for a sputtering target, which can suppress the generation of particles during sputtering without performing hot isostatic pressing.

Means for solving the problems

In general, it is known that the higher the sintering temperature, the higher the density of the sintered body. However, the present inventors confirmed the following phenomenon: when the sintering temperature in the production of the Fe-Pt-oxide-BN sintered body is set to 950 ℃ or higher and 1300 ℃ or lower, which is a conventional normal sintering temperature, the relative density is rather decreased, and a large amount of fine particles are generated during sputtering.

The present inventors have intensively studied the cause of the decrease in relative density at a high sintering temperature in the production of an Fe-Pt-oxide-BN sintered body, and as a result, have found that the N content of the Fe-Pt-oxide-BN sintered body after sintering at a high sintering temperature is lower than the theoretical value. The reason why the N content decreased is considered to be that BN is decomposed by long-time contact with an oxide and high-temperature sintering to generate nitrogen gas or nitrogen oxide gas, and the optimum conditions for suppressing the decomposition of BN and the generation of nitrogen gas or nitrogen oxide gas were found from the mixing conditions of BN and the oxide and the sintering conditions, thereby completing the present invention.

According to the present invention, the following Fe-Pt-oxide-BN sintered body for a sputtering target can be provided.

[1] An Fe-Pt-oxide-BN sintered body for a sputtering target, wherein the mass ratio N/B of N to B is in the range of 1.30+ -0.1.

[2] The Fe-Pt-oxide-BN sintered body for a sputtering target according to the above [1], wherein the relative density measured by the Archimedes method is 92.0% or more.

[3] The Fe-Pt-oxide-BN sintered body for a sputtering target according to the above [1] or [2], wherein Pt is 33 mol% or more and 60 mol% or less, BN and the oxide in total are 5 mol% or more and 40 mol% or less, and the balance is Fe and unavoidable impurities.

[4] The Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of the above items [1] and [2], wherein Pt is 33 mol% or more and 60 mol% or less, BN and an oxide are 5 mol% or more and 40 mol% or less in total, 1 or more selected from Co, Zn, Ge, Rh, Ru and Pd are 1 mol% or more and 15 mol% or less, and the balance is Fe and unavoidable impurities.

[5] The Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of the above items [1] and [2], wherein Pt is 33 mol% or more and 60 mol% or less, BN and an oxide in total are 5 mol% or more and 40 mol% or less, C is 1 mol% or more and 15 mol% or less, and the balance is Fe and unavoidable impurities.

[6] The Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of the above [1] to [5], wherein the oxide is selected from oxides of Si, Ti and Ta.

[7] A method for producing the Fe-Pt-oxide-BN sintered body for a sputtering target according to any one of the above [1] to [6], wherein a metal powder, an oxide powder and a BN powder are mixed and sintered at a temperature of 850 ℃ or lower.

[8] A method for producing the Fe-Pt-oxide-BN based sintered body for a sputtering target according to any one of the above [1] to [6], wherein a FePt based alloy powder and an oxide powder are mixed to form a composite oxide alloy powder in which an oxide is finely dispersed in the FePt based alloy, then a BN powder is added to the composite oxide alloy powder to form a BN-containing composite oxide alloy powder, and then the BN-containing composite oxide alloy powder is sintered at a temperature of 850 ℃ or lower.

[9] A method for producing the Fe-Pt-oxide-BN based sintered body for a sputtering target according to any one of the above [1] to [6], wherein a FePt based alloy powder and an oxide powder are strongly mixed to form a composite oxide alloy powder in which an oxide is finely dispersed in a FePt based alloy, then a BN powder is added to the composite oxide alloy powder and weakly mixed to form a composite oxide alloy powder containing BN, and then the composite oxide alloy powder containing BN is sintered at a temperature of 850 ℃ or lower.

Effects of the invention

The Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention can provide a high-density sputtering target in which the amount of fine particles generated during sputtering is reduced.

According to the present invention, a high-density Fe-Pt-oxide-BN sintered body for a sputtering target, which reduces the amount of fine particles generated during sputtering, can be produced by low-temperature sintering without hot isostatic pressing.

Detailed Description

According to the present invention, it is possible to provide an Fe-Pt-oxide-BN based sintered body for a sputtering target, wherein the mass ratio N/B of N to B is in the range of 1.30. + -. 0.1, preferably in the range of 1.30+ 0.1. BN (boron nitride) is present as a nonmagnetic material together with the oxide between Fe-Pt alloy phases as magnetic bodies, and constitutes a partition wall. The present inventors have studied a sputtering target in which a large amount of fine particles are generated, and as a result, have found the following phenomenon: in the Fe-Pt-oxide-BN-based sintered body, the mass ratio N/B of N (nitrogen) to B (boron) is less than the stoichiometric ratio. From this, it is considered that BN (boron nitride) is decomposed by contact with the oxide, N is discharged as nitrogen gas or nitrogen oxide gas by decomposition of BN, and BN and the oxide are easily peeled off in the form of fine particles, and the following finding is obtained: in order to suppress the generation of fine particles, it is effective to prevent decomposition of BN. The mass ratio N/B of N to B of 1.30 ± 0.1 means that BN is suppressed from decomposing into B and N, and N is not excessively reduced without being discharged in the form of nitrogen gas and nitrogen oxide gas, and is substantially equal to the mass ratio 1.30 when the stoichiometric ratio of B and N is 1.

The Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention has a relative density of 92.0% or more, preferably 94.0% or more, and more preferably 95.0% or more. In general, the relative density of the BN-containing Fe-Pt-oxide sintered body is low, and therefore, it can be said that the relative density of 92.0% or more is extremely high. In the present application, the "relative density" is measured by the archimedes method.

The composition of the Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention is: 33 to 60 mol% of Pt, 5 to 40 mol% of BN and oxide in total, and the balance of Fe and inevitable impurities; or Pt is 33 mol% or more and 60 mol% or less, BN and an oxide in total are 5 mol% or more and 40 mol% or less, 1 or more selected from Co, Zn, Ge, Rh, Ru and Pd are 1 mol% or more and 15 mol% or less, and the balance is Fe and unavoidable impurities; or Pt is 33 mol% or more and 60 mol% or less, BN and an oxide in total are 5 mol% or more and 40 mol% or less, C is 1 mol% or more and 15 mol% or less, and the balance is Fe and unavoidable impurities. BN and the oxide are contained in an appropriate ratio, if the total content is more than 0 mol% and not more than 5 mol% and not more than 40 mol%, but BN is preferably not less than 1 mol% and not more than 30 mol%% of the oxide is preferably 1 mol% or more and 15 mol% or less. The oxide includes oxides of Si, Ti or Ta, and SiO are preferable₂、Si₃O₂、TiO、TiO₂、Ti₂O₃More preferably SiO₂、TiO₂、Ta₂O₅。

The Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention has a Pt content of 33 mol% or more and 60 mol% or less, preferably 33 mol% or more and 52 mol% or less, and more preferably 35 mol% or more and 47 mol% or less.

The Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention has a total content of BN and oxide of 5 mol% or more and 40 mol% or less, preferably 5 mol% or more and 35 mol% or less, and more preferably 6 mol% or more and 30 mol% or less. The content of BN is 1 mol% or more and 30 mol% or less, preferably 2 mol% or more and 28 mol% or less, and more preferably 3 mol% or more and 25 mol% or less. The content of the oxide is 1 mol% or more and 15 mol% or less, preferably 2 mol% or more and 15 mol% or less, and more preferably 3 mol% or more and 15 mol% or less. When the amount is within the above range, the material functions well as a grain boundary material.

The content of these metals in the Fe-Pt-oxide-BN sintered body for a sputtering target containing 1 or more selected from Co, Zn, Ge, Rh, Ru and Pd is 1 mol% or more and 15 mol% or less, preferably 1 mol% or more and 13 mol% or less, and more preferably 1 mol% or more and 10 mol% or less. When the amount is within the above range, the magnetic properties of the Fe-Pt alloy can be satisfactorily maintained.

The content of C in the Fe-Pt-oxide-BN sintered body for a sputtering target containing C is 1 mol% or more and 15 mol% or less, preferably 1 mol% or more and 13 mol% or less, and more preferably 1 mol% or more and 10 mol% or less. When the amount is within the above range, BN and the oxide function well as a grain boundary material, and Fe-Pt alloy particles are isolated, whereby the magnetic properties of the Fe-Pt alloy can be maintained well.

The Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention can be produced as follows: the metal powder, the oxide powder and the BN powder are mixed and sintered at a low temperature of 850 ℃ or less, preferably 830 ℃ or less, more preferably 800 ℃ or less, and 730 ℃ or more, preferably 750 ℃ or more. The mixing of the metal powder, the oxide powder and the BN powder is preferably performed with a weak mixing of, for example, 300rpm for about 30 minutes. By relaxing the mixing conditions, the BN and the oxide can be prevented from being excessively contacted, and by lowering the sintering temperature, the reaction of the BN and the oxide can be suppressed, and the decomposition of the BN can be prevented. On the other hand, when the mixing time is too short, dispersibility is deteriorated, and therefore, the mixing time is preferably 15 minutes or more and 45 minutes or less. Here, the "metal powder" refers to 1 or more kinds of metal powder selected from Co, Zn, Ge, Rh, Ru, and Pd, which can be used as a component of the Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention, or alloy powder thereof, in addition to the Fe metal powder and the Pt metal powder.

Alternatively, the Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention can be produced by: the method comprises mixing an FePt-based alloy powder and an oxide powder to form a composite oxide alloy powder in which an oxide is finely dispersed in an FePt-based alloy, adding a BN powder to the composite oxide alloy powder to form a BN-containing composite oxide alloy powder, and sintering the BN-containing composite oxide alloy powder at a low temperature of 850 ℃ or less, preferably 830 ℃ or less, more preferably 800 ℃ or less, and 730 ℃ or more, preferably 750 ℃ or more.

The composite oxide alloy powder containing BN as a sintering precursor is formed by: the composite oxide alloy powder in which an oxide is finely dispersed in the FePt-based alloy obtained by mixing the FePt-based alloy powder and the oxide powder is mixed with a BN powder. By forming the composite oxide alloy powder in which the oxide is finely dispersed in the FePt-based alloy at first, the FePt-based alloy and the oxide can be finely and uniformly dispersed, and the BN powder added later can be prevented from excessively contacting the oxide.

Preferably, the composite oxide alloy powder is prepared by strong mixing, and the composite oxide alloy powder containing BN is prepared by weak mixing. In the present application, strong mixing means mixing that provides large mixing energy for 1 hour or more at a rotation speed of 300rpm or more, and weak mixing means mixing that provides small mixing energy for less than 1 hour at a rotation speed of 300rpm or less. The rotation speed and the mixing time of the strong mixing and the weak mixing may be appropriately adjusted within the above-described ranges according to the composition of the composite oxide alloy powder and the composite oxide alloy powder containing BN and the desired dispersion state of the oxides. For example, when a composite oxide alloy powder in which oxides are more uniformly dispersed is obtained, it is preferable to perform intensive mixing at a rotation speed of 300rpm or more for 20 hours or more. The higher the rotational speed, the longer the mixing time and the greater the mixing energy. For example, the mixture may be mixed at 400rpm for 10 hours or more. In the mixing of the composite oxide alloy powder and the BN powder, it is preferable to perform weak mixing at a rotation speed of 300rpm or less for 30 minutes or less in order to further suppress the reaction between BN and the oxide.

The sintering temperature of the BN-containing composite oxide alloy powder depends on the desired composition of the sintered body, but is considerably lower than the conventional general sintering temperature of 900 ℃ or higher and 1400 ℃ or lower. By sintering at a low temperature of 850 ℃ or lower, preferably 830 ℃ or lower, more preferably 800 ℃ or lower and 730 ℃ or higher, preferably 750 ℃ or higher, decomposition of BN caused by contact of BN with the oxide can be suppressed, and the density of the sintered body can be increased.

In the case where the Fe-Pt-oxide-BN sintered body for a sputtering target of the present invention contains 1 or more selected from Co, Zn, Ge, Rh, Ru and Pd as additional components, these metals may be mixed as elemental powders or alloy powders with the Fe metal powder and the Pt metal powder together with the oxide powder and the BN powder, or may be mixed with the FePt alloy powder together with the oxide powder and then mixed with the BN powder.