Magnetic material target and magnetic material target assembly

Abstract

To provide a magnetic material target which includes, as a main component, Co which is restrained well in generation of particles in producing a sputter membrane, and includes an oxide, and provide a magnetic material target assembly.SOLUTION: A magnetic material target includes any one or more of Pt, Cr, Ru, B, and Ti, and an oxide. The balance includes Co and selectively includes impurities. The sum of concentrations of Co, Pt, Cr, Ru, and Ti is 50 at% or more. The concentration of B is 9 at% or more. The concentration of O is 13.5 at% or more. The oxide includes an oxide of B. The number of oxides each having an area of more than 3.0 μm2 per an observation visual field area of 11569 μm2 is 60 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic material target and a magnetic material target assembly, and mainly to a magnetic material target for the production of a film for a HDD. [Background technology]

[0002] The layers that make up hard disk drives (HDDs) that employ perpendicular magnetic recording are made of materials based on ferromagnetic metals such as Co, Fe, and Ni, and the recording layer is often made of a composite material consisting of a ferromagnetic alloy, such as a Co-Cr, Co-Pt, or Co-Cr-Pt alloy, with Co as the main component, and a non-magnetic inorganic material. Due to its high productivity, thin films for magnetic recording media such as those in hard disk drives are often produced by sputtering a magnetic target composed of the above materials.

[0003] In general, magnetic material targets are manufactured by first pulverizing and mixing raw material powders, and then hot-pressing the resulting mixture to obtain a sintered body. To increase the density of the sintered body, HIP (Hot Isostatic Pressing) processing may then be performed. The sintered body thus obtained is then machined on a lathe to produce a target of a predetermined shape (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6445126 [Patent Document 2] Patent No. 6332869 [Patent Document 3] Patent No. 6958819 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, composite materials consisting of a Co-based ferromagnetic alloy and a non-magnetic inorganic material are useful for the recording layer of HDDs, and are sputter-deposited by HDD media manufacturers to form thin films with a granular structure in which magnetic particles are separated by oxide grain boundaries. In recent years, there has been a trend toward increasing the proportion of B oxides among the added oxides in perpendicular magnetic recording media that use Co-based magnetic particles.

[0006] One of the problems encountered during sputter deposition of magnetic material targets containing oxides and primarily composed of Co is the generation of arcing from coarse oxides. Arcing generates particles that adhere to the substrate, resulting in reduced media yield. For this reason, in the manufacture of magnetic material targets containing oxides and primarily composed of Co, it has been important to produce targets in which the oxides are finely dispersed within the master alloy phase. Meanwhile, boron oxides have a low melting point among the oxide species added to magnetic material targets containing oxides and primarily composed of Co, and the amount of boron oxide added has been increasing in recent years. This has made it difficult to produce targets with finely dispersed oxides using conventional techniques, making it more likely for particles to be generated during sputter deposition.

[0007] Therefore, an object of an embodiment of the present invention is to provide a magnetic material target and a magnetic material target assembly that contain oxides and that are primarily composed of Co, in which particle generation during sputtering film formation is effectively suppressed. [Means for solving the problem]

[0008] The above problems are solved by the present invention, which is specified as follows. (1) one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally containing impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B, Observation field area: 11569 μm 2 per 3.0μm 2 The number of oxides having an area of ​​more than 60 is 60 or less. (2) one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally containing impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B, Observation field area: 11569 μm 2 per 2.5μm 2 The number of oxides having an area of ​​more than 100 is 100 or less. (3) one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally containing impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B, Observation field area: 11569 μm 2 per 2.0μm 2 The number of oxides having an area of ​​more than 150 is 150 or less. (4) one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally containing impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B, Observation field area: 11569 μm 2 per 1.0μm 2 The number of oxides having an area of ​​more than 400 is 400 or less. (5) 1.0 μm 2 The number of oxides having an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The magnetic material target according to any one of (1) to (4), wherein the value obtained by dividing the area by the number of the oxides having the following area is 0.70 or less. (6) 0.5 μm 2 Ultra~1.0μm 2 The number of oxides having an area of ​​1.0 μm or less was determined. 2 The magnetic material target according to any one of (1) to (5), wherein a value obtained by dividing the area by the number of the oxides having an area of ​​more than 1.5 is 1.5 or more. (7) The magnetic material target according to any one of (1) to (6), wherein the oxide further contains one or more oxides of elements selected from Al, Si, Ba, Be, Ca, Ce, Cr, Co, Dy, Er, Eu, Ga, Gd, Ho, Li, Mg, Mn, Nb, Nd, Pr, Sc, Sm, Sr, Ta, Tb, Ti, V, Y, Zn, and Zr. (8) The magnetic material target according to any one of (1) to (7), a backing plate bonded to the magnetic material target; 1. A magnetic material target assembly comprising: [Effects of the Invention]

[0009] According to an embodiment of the present invention, it is possible to provide a magnetic material target and a magnetic material target assembly that contain oxides and that are mainly composed of Co, in which particle generation during sputtering film formation is effectively suppressed. [Brief explanation of the drawings]

[0010] [Figure 1] This shows an example of a binarized image and the original image in image analysis using ImageJ. [Figure 2]This is a screenshot of the settings for binarization processing using ImageJ. [Figure 3] 1 is an SEM image of Example 1. [Figure 4] 1 is an SEM image of Example 2. [Figure 5] 10 is an SEM image of Example 3. [Figure 6] 1 is an SEM image of Example 4. [Figure 7] 1 is an SEM image of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, embodiments of the present invention will be described in detail with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that appropriate design changes and improvements may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0012] <Magnetic material target> The shape of the magnetic material target according to the embodiment of the present invention is not particularly limited, and may be a flat plate (including a disk or rectangular plate), a cylindrical shape, or any other shape.

[0013] The magnetic material target according to the embodiment of the present invention contains one or more of Pt, Cr, Ru, and Ti, an oxide, and the balance is Co and selectively contained impurities. By using the magnetic material target according to the embodiment of the present invention as a sputtering target, it is possible to produce a thin film for a magnetic recording medium such as a hard disk drive (HDD).

[0014] In the magnetic material target according to the embodiment of the present invention, the total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more. When the total concentration of Co, Pt, Cr, Ru, and Ti in the magnetic material target is 50 at% or more, the magnetic properties are improved. There is no particular upper limit on the total concentration of Co, Pt, Cr, Ru, and Ti in the magnetic material target, but from the viewpoint of ensuring grain boundary material, it is preferably 90 at% or less. Furthermore, the total concentration of Co, Pt, Cr, Ru, and Ti in the magnetic material target is more preferably 50 to 85 at%, and even more preferably 50 to 80 at%. Furthermore, the concentration of Cr is preferably 10 at% or less, and more preferably 7 at% or less.

[0015] The magnetic material target according to the embodiment of the present invention has a B concentration of 9 at% or more and an O concentration of 13.5 at% or more. With such a configuration, a particularly preferable magnetic thin film can be obtained. In the magnetic material target according to the embodiment of the present invention, the B concentration is preferably 10 to 16 at%, more preferably 11 to 15 at%. In the magnetic material target according to the embodiment of the present invention, the O concentration is preferably 15 to 28 at%, more preferably 16 to 26 at%.

[0016] The magnetic material target according to the embodiment of the present invention contains an oxide of B. An example of the oxide of B is B2O3. Here, how to determine whether B is contained in the form of B2O3 in the magnetic material target according to the embodiment of the present invention will be described below. First, the magnetic material target is cut and its cross section is mirror-polished to obtain a sample for microstructure observation. More specifically, the cross section of the magnetic material target is polished using abrasive cloths ranging from P80 to P2000 in order to obtain a polished cross section, and finally buffed using aluminum oxide abrasive grains with a particle size of 0.3 μm to obtain a sample for microstructure observation with a polished cross section. Furthermore, aluminum oxide and granular polishing debris adhering to the polished surface are thoroughly removed by cleaning. Next, elemental mapping is performed on the sputtered surface of the mirror-polished sample by WDX mapping analysis (wavelength-dispersive X-ray mapping spectroscopy) in a 50 μm × 50 μm field of view using a field emission electron probe microanalyzer (FE-EPMA). WDX mapping analysis in a 50 μm × 50 μm field of view using the FE-EPMA is performed at an acceleration voltage of 15.0 kV and a probe current of 2.0 × 10 -8 This can be done by performing a stage scan under the conditions of A. At this time, if the areas where the detection intensity of B and O are high coincide with each other, it is considered that the B is mostly present in the sintered body as an oxide. Therefore, B where the area where the detection intensity is high coincides with O is determined to be present in the form of B2O3. In addition to B2O3, the oxide may further contain one or more oxides of elements selected from Al, Si, Ba, Be, Ca, Ce, Cr, Co, Dy, Er, Eu, Ga, Gd, Ho, Li, Mg, Mn, Nb, Nd, Pr, Sc, Sm, Sr, Ta, Tb, Ti, V, Y, Zn, and Zr in order to further improve the magnetic properties.

[0017] The magnetic material target according to the embodiment of the present invention has an oxide volume fraction of 30 vol.% or more. When the oxide volume fraction in the magnetic material target is 30 vol.% or more, the magnetic properties are further improved. There is no particular upper limit to the oxide volume fraction in the magnetic material target, but from the viewpoint that if there is too much oxide, the magnetic properties deteriorate, it is preferably 60 vol.% or less. Furthermore, the oxide volume fraction in the magnetic material target is more preferably 30 to 55 vol.%, and even more preferably 30 to 50 vol.%. The oxide volume fraction can be calculated from the composition of the target, and the volume of each component contained in the target is calculated by (content of each material: mol) x (molecular weight of each material: g / mol) x (reciprocal of density of each material: cm 3 Next, the volume fraction of oxides can be calculated by dividing the total volume of only oxides by the total volume of all components.

[0018] The remainder of the magnetic material target according to the embodiment of the present invention may or may not contain impurities. Examples of such impurities include metal elements such as Fe, Ni, Cu, Zr, Al, W, V, Zn, Sn, and Ta, as well as simple or compound elements such as C or N from gas components such as carbon dioxide and nitrogen in the atmosphere. The impurity content of the remainder of the magnetic material target according to the embodiment of the present invention may be 0.5 mol% or less, or 0.15 mol% or less. Furthermore, the impurities can be analyzed by collecting an analytical sample from the magnetic material target and using infrared absorption spectroscopy, an ICP optical emission spectrometer, or GDMS (glow discharge mass spectrometry). The amount and shape of the analytical sample vary depending on the analytical method used, and the optimal amount and shape for each method can be selected.

[0019] The magnetic material target according to the embodiment of the present invention has an observation field area of ​​11569 μm 2 per 3.0μm 2In the magnetic material target according to the embodiment of the present invention, as described above, the oxide contains an oxide of B, with a B concentration of 9 at% or more and an O concentration of 13.5 at% or more. Generally, the higher the oxygen concentration, the higher the possibility that coarse oxides will be contained, which makes arcing more likely to occur during sputtering film formation, resulting in the problem of particles being generated. In contrast, the magnetic material target according to the embodiment of the present invention has an O concentration of 13.5 at% or more, yet has an observation field area of ​​11569 μm 2 per 3.0μm 2 The number of oxides with an area of ​​more than 10 ... 2 per 3.0μm 2 The number of oxides having an area of ​​more than 11569 μm is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, and even more preferably 20 or less. 2 per 3.0μm 2 The lower limit of the number of oxides having an area of ​​more than 1000 nm is not particularly limited, but may be 0 or more, 1 or more, or 3 or more.

[0020] In another aspect, the magnetic material target according to the embodiment of the present invention has an observation field area of ​​11569 μm 2 per 2.5μm 2In the magnetic material target according to the embodiment of the present invention, as described above, the oxide contains an oxide of B, with a B concentration of 9 at% or more and an O concentration of 13.5 at% or more. Generally, the higher the oxygen concentration, the higher the possibility that coarse oxides will be contained, which makes arcing more likely to occur during sputtering film formation, resulting in the problem of particles being generated. In contrast, the magnetic material target according to the embodiment of the present invention has an O concentration of 13.5 at% or more, yet has an observation field area of ​​11569 μm 2 per 2.5μm 2 The number of oxides with an area of ​​more than 100 is controlled to 100 or less. As a result, the oxide structure is sufficiently fine, and the occurrence of arcing during sputtering film formation is effectively suppressed. Since the sputtering rate of oxides is slower than that of metals, it is thought that if sputtering discharge is carried out for a long period of time, oxides will remain in the form of protrusions. It is thought that arcing occurs due to electric field concentration on these protrusions. Here, if the oxide structure is sufficiently fine, the remaining protrusions will be small, making electric field concentration less likely to occur and arcing less likely to occur. Observation field area: 11569 μm 2 per 2.5μm 2 The number of oxides having an area of ​​more than 11569 μm is preferably 75 or less, more preferably 55 or less, even more preferably 45 or less, and even more preferably 25 or less. 2 per 2.5μm 2 The lower limit of the number of oxides having an area of ​​more than 1000 nm is not particularly limited, but may be 0 or more, 1 or more, 2 or more, or 4 or more.

[0021] In yet another aspect, the magnetic material target according to the embodiment of the present invention has an observation field area of ​​11569 μm 2 per 2.0μm 2In the magnetic material target according to the embodiment of the present invention, as described above, the oxide contains an oxide of B, with a B concentration of 9 at% or more and an O concentration of 13.5 at% or more. Generally, the higher the oxygen concentration, the higher the possibility that coarse oxides will be contained, which makes arcing more likely to occur during sputtering film formation, resulting in the problem of particles being generated. In contrast, the magnetic material target according to the embodiment of the present invention has an O concentration of 13.5 at% or more, yet has an observation field area of ​​11569 μm 2 per 2.0μm 2 The number of oxides with an area of ​​more than 100 is controlled to 150 or less. As a result, the oxide structure is sufficiently fine, and the occurrence of arcing during sputtering film formation is effectively suppressed. Since the sputtering rate of oxides is slower than that of metals, it is thought that if sputtering discharge is carried out for a long period of time, oxides will remain in the form of protrusions. It is thought that arcing occurs due to electric field concentration on these protrusions. Here, if the oxide structure is sufficiently fine, the remaining protrusions will be small, making electric field concentration less likely to occur and arcing less likely to occur. Observation field area: 11569 μm 2 per 2.0μm 2 The number of oxides having an area of ​​more than 11569 μm is preferably 100 or less, more preferably 80 or less, even more preferably 50 or less, and even more preferably 30 or less. 2 per 2.0μm 2 The lower limit of the number of oxides having an area of ​​more than 1000 nm is not particularly limited, but may be 0 or more, 1 or more, 2 or more, 3 or more, or 5 or more.

[0022] In yet another aspect, the magnetic material target according to the embodiment of the present invention has an observation field area of ​​11569 μm 2 per 1.0μm 2In the magnetic material target according to the embodiment of the present invention, as described above, the oxide contains an oxide of B, with a B concentration of 9 at% or more and an O concentration of 13.5 at% or more. Generally, the higher the oxygen concentration, the higher the possibility that coarse oxides will be contained, which makes arcing more likely to occur during sputtering film formation, resulting in the problem of particles being generated. In contrast, the magnetic material target according to the embodiment of the present invention has an O concentration of 13.5 at% or more, yet has an observation field area of ​​11569 μm 2 per 1.0μm 2 The number of oxides with an area of ​​more than 400 is controlled to 400 or less. As a result, the oxide structure is sufficiently fine, and the occurrence of arcing during sputtering film formation is effectively suppressed. Since the sputtering rate of oxides is slower than that of metals, it is thought that if sputtering discharge is carried out for a long period of time, oxides will remain in the form of protrusions. It is thought that arcing occurs due to electric field concentration on these protrusions. Here, if the oxide structure is sufficiently fine, the remaining protrusions will be small, making electric field concentration less likely to occur and arcing less likely to occur. Observation field area: 11569 μm 2 per 1.0μm 2 The number of oxides having an area of ​​more than 11569 μm is preferably 300 or less, more preferably 200 or less, and even more preferably 150 or less. 2 per 1.0μm 2 The lower limit of the number of oxides having an area of ​​more than 1000 nm is not particularly limited, but may be 20 or more, or may be 50 or more.

[0023] The magnetic material target according to the embodiment of the present invention has a thickness of 1.0 μm 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 According to this configuration, it is preferable that the value obtained by dividing the area by the number of oxides having an area of ​​1.0 μm or less is 0.70 or less. 2 The number of oxides with a large area of ​​over 0.5 μm 2 Ultra~1.0μm2 Since the oxide particles are present at a ratio of 0.70 or less to the number of oxide particles having a small area of ​​1.0 μm or less, the oxide structure is sufficiently fine, and the occurrence of arcing during sputtering deposition is effectively suppressed. 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The value divided by the number of oxides having an area of ​​1.0 μm or less is more preferably 0.6 or less, even more preferably 0.4 or less, even more preferably 0.3 or less, and even more preferably 0.2 or less. 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The lower limit of the value divided by the number of oxides having the following area is not particularly limited, but may be 0.0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, or 0.1 or more.

[0024] The magnetic material target according to the embodiment of the present invention has a thickness of 0.5 μm 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 It is preferable that the value obtained by dividing the area by the number of oxides having an area of ​​more than 0.5 μm is 1.5 or more. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less 2 Since the oxides are present at a ratio of 1.5 or more to the number of oxides having a large area of ​​over 0.5 μm, the oxide structure is sufficiently fine, and the occurrence of arcing during sputtering deposition is effectively suppressed. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2The value obtained by dividing the area by the number of oxides having an area of ​​more than 0.5 μm is more preferably 1.5 or more, even more preferably 2.5 or more, even more preferably 3.5 or more, and even more preferably 4.5 or more. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 The upper limit of the value obtained by dividing the value by the number of oxides having an area of ​​more than 1000 is not particularly limited, but may be 8.0 or less, or may be 6.0 or less.

[0025] The observation field area of ​​the magnetic material target according to the embodiment of the present invention is 11569 μm 2 per 3.0μm 2 Oxide with an area of ​​more than 2.5 μm 2 Oxides with an area of ​​more than 2.0 μm 2 Oxides with an area of ​​more than 1.0 μm 2 Number of oxides with an area greater than 0.5 μm 2 Ultra~1.0μm 2 The method for measuring the number of oxides having the following areas will be described in detail. First, a magnetic material target is cut and its cross section is mirror-polished to obtain a sample for microstructure observation. More specifically, in this mirror-polishing, the cross section of the magnetic material target is polished in order using abrasive cloths and papers with grit sizes ranging from P80 to P2000, and finally buffed with aluminum oxide abrasive grains with a particle size of 0.3 μm to obtain a sample for microstructure observation with a polished cross-section surface. At this time, aluminum oxide and granular polishing debris adhering to the polished surface are thoroughly removed by washing. Next, a secondary electron image of the mirror-polished sputtered surface of the sample is taken using an FE-SEM (product name: SU3900, manufactured by Hitachi High-Tech Corporation) at an accelerating voltage of 15 kV and a magnification of 1000. In the secondary electron image, the metal matrix phase appears as a brighter area than the surrounding area, and the oxide appears as a darker area than the surrounding area. Next, the SEM image (field of view 11569 μm 2The image was binarized using the mode method with image processing software (ImageJ, manufactured by the National Institutes of Health), and the area of ​​each oxide was measured using the Analyze Particulates function of the image processing software. The particles (oxides) in the field of view were extracted, and the area of ​​each particle was calculated. 2 Oxide with an area of ​​more than 2.5 μm 2 Oxides with an area of ​​more than 2.0 μm 2 Oxides with an area of ​​more than 1.0 μm 2 Oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The number of oxides having the following areas is counted. The ImageJ binarization is performed according to the following steps (1) to (5). (1) Load an SEM image with a 1000x magnification from File → Open on the ImageJ toolbar. (2) Select 8-bit from Image → Type. Draw a line along the scale bar, and select Analyze → Set scale to set the scale size. (3) Select the part of the image excluding the scale and cut out the scale part by using Image → Crop. (4) Select Process → Filters → Gaussian Blur, enter 2 for Sigma, and click OK. (5) Select Process → Binary → Make Binary. This completes the binarization of the image. As described above, the areas that are darker than the surrounding area, which are classified as black by the binarization process, are converted to black, and the black areas are considered to be oxides. The threshold for the binarization process is automatically set from the color histogram in the image. Figure 1 shows an example of an image binarized by ImageJ and the original image.

[0026] <Magnetic target assembly> The magnetic material target according to the embodiment of the present invention may be bonded to a backing plate as needed to form a magnetic material target assembly. The magnetic material target assembly can be mounted in a sputtering apparatus for use. Indium or indium tin can be used as the brazing material. The magnetic material target according to the embodiment of the present invention may be mounted directly in a sputtering apparatus for use without using a backing plate. The material of the backing plate is not particularly limited, and examples thereof include Cu, Ti, Mo, and alloys containing at least one of these (e.g., Cu-Ni-Si alloys (e.g., C18000, etc.), CuZn alloys, and CuCr alloys). It is preferable that the material of the backing plate has high thermal conductivity, and from this viewpoint, Cu is suitable.

[0027] <Magnetic material target manufacturing method> A method for manufacturing a magnetic material target according to an embodiment of the present invention will be described in detail below. The magnetic material target according to the embodiment of the present invention can be fabricated by a powder sintering method. First, powders of each metal element are prepared. Alternatively, alloy powders of these metals (e.g., Co-Pt powder) may be used instead of the powders of each metal element. Co powder, CrBO powder, Pt powder, CoBO powder, and CoB powder are particularly preferred. Using BO powder as a raw material is undesirable because it may result in the inclusion of coarse oxides in the resulting magnetic material target. The 50% cumulative volumetric particle size D50 (average particle size D50) of each raw material powder can be as follows: Co powder: 1-10 μm, CrBO powder: 0.5-5 μm, Pt powder: 1-10 μm, CoBO powder: 1-20 μm, and CoB powder: 1-50 μm. The purity of these raw materials is usually 2N (99% by mass) or higher, preferably 3N (99.9% by mass) or higher, and more preferably 4N (99.99% by mass) or higher. If the purity is lower than 2N, the sintered body will contain a large amount of impurities, which can cause problems such as not being able to obtain the desired physical properties (for example, generation of particles due to arcing). These raw materials can be appropriately prepared based on the composition and purity of the desired sintered body.

[0028] These metal powders are then weighed to obtain the desired composition and mixed using a mixer that also serves as a pulverizer. Non-magnetic particles may also be mixed with the metal powder at this stage. Mixing devices such as a ball mill or mortar can be used, but it is preferable to use a powerful mixing method such as a ball mill. Considering the problem of oxidation during mixing, it is preferable to mix the materials in an inert gas atmosphere or in a vacuum.

[0029] Here, the mixing is performed by carrying out primary mixing, followed by sieving, and then secondary mixing. The primary mixing is performed for 5 to 30 hours. The secondary mixing is performed for 5 to 30 hours. By increasing the mixing time of the raw materials, the observation field area is increased to 11569 μm. 2 per 3.0μm 2 Number of oxides with an area greater than 2.5 μm 2 Number of oxides with an area greater than 2.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm can be reduced. 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The area divided by the number of oxides with an area of ​​less than 0.5 μm can be reduced. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 On the other hand, by shortening the mixing time of the raw materials, the observation field area of ​​11569 μm 2 per 3.0μm 2 Number of oxides with an area greater than 2.5 μm 2 Number of oxides with an area greater than 2.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm can be increased. 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2The area divided by the number of oxides with an area of ​​less than 0.5 μm can be increased. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 The value obtained by dividing the number of oxides having an area of ​​more than 11569 μm by the number of oxides having an area of ​​more than 11569 μm can be reduced. In addition, by performing sieving between the primary mixing and the secondary mixing, coarse powder can be removed, and fine powder can be increased in the secondary mixing. As a result, coarsening of the oxides can be suppressed. The sieving is performed using a sieve with openings of 150 to 400 μm. From this perspective, by adjusting the mixing time of the raw materials, it is possible to obtain an observation field area of ​​11569 μm. 2 per 3.0μm 2 Number of oxides with an area greater than 2.5 μm 2 Number of oxides with an area greater than 2.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 Divide by the number of oxides with an area of ​​less than 0.5 μm 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 The value divided by the number of oxides having an area of ​​more than 1000 can be controlled.

[0030] The mixed powder thus obtained is molded and sintered using a hot press to produce a sintered body. The molding and sintering method is not limited to hot pressing; plasma discharge sintering and hot isostatic sintering can also be used. The sintering conditions are 650-1400°C for 0.5-12 hours. By increasing the sintering temperature and / or lengthening the sintering time, the observation field area can be increased to 11569 μm. 2 per 3.0μm 2 Number of oxides with an area greater than 2.5 μm 2 Number of oxides with an area greater than 2.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2The number of oxides with an area of ​​more than 1.0 μm can be increased. 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The area divided by the number of oxides with an area of ​​less than 0.5 μm can be increased. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 On the other hand, if the sintering temperature is lowered and / or the sintering time is shortened, the observed field area is 11569 μm 2 per 3.0μm 2 Number of oxides with an area greater than 2.5 μm 2 Number of oxides with an area greater than 2.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm can be reduced. 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The area divided by the number of oxides with an area of ​​less than 0.5 μm can be reduced. 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 From this perspective, by adjusting the sintering temperature and sintering time, it is possible to increase the value obtained by dividing the observed field area by the number of oxides having an area of ​​11569 μm. 2 per 3.0μm 2 Number of oxides with an area greater than 2.5 μm 2 Number of oxides with an area greater than 2.0 μm 2 Number of oxides with an area greater than 1.0 μm 2 The number of oxides with an area of ​​more than 1.0 μm 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 Divide by the number of oxides with an area of ​​less than 0.5 μm 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted.2 The value divided by the number of oxides having an area of ​​more than 1000 can be controlled.

[0031] The sintered body is then removed from the hot press and subjected to HIP (Hot Isostatic Pressing). HIP is an effective method for increasing the density of the sintered body. The holding temperature during HIP is 650-1100°C, the holding time is 0.5-12 hours, and the pressure is 100 MPa or more. The sintered body thus obtained is then machined into the desired shape on a lathe to produce a magnetic material target.

[0032] <Film formation method using a magnetic material target> The magnetic material target according to the embodiment of the present invention can be used to form a thin film that mainly constitutes a magnetic recording medium. Specifically, a sputtering device is used to sputter the surface of the magnetic material target with accelerated argon ions, causing particles (sputtered particles) to be emitted from the magnetic material target, and the sputtered particles are deposited on the surface of a substrate previously placed opposite the target, thereby forming a thin film on the surface of the substrate. Sputtering conditions can be appropriately set depending on the desired film thickness, composition, etc. [Example]

[0033] Examples of the present invention are given below, but these examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

[0034] Example 1 The magnetic material target according to Example 1 was manufactured by the following manufacturing method. As raw material powders, 3N (99.9 mass%) Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were prepared and weighed to have a composition of Co-Pt-Cr-BO (Pt 10-20 at%, Cr 0.5-7 at%, B 11-15 at%, O 16-26 at%, Co (balance)). The raw material powders were prepared so that the total composition was 100 at%. The 50% cumulative volume particle size D50 (average particle size D50) of the raw material powders was as follows: Co powder: 4μm, CrBO3 powder: 1μm, Pt powder: 3μm, Co2B2O5 powder: 8μm, Co2B powder: 3μm Next, the weighed Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were placed in a ball mill pot together with zirconia balls, and the mixture was subjected to primary mixing for 10 hours, sieving through a sieve with 150 μm openings, and secondary mixing for 10 hours, in that order.

[0035] Next, the mixed powder removed from the ball mill pot was filled into a carbon mold and hot-pressed. The hot-pressing conditions were a vacuum atmosphere, a heating rate of 300°C / hour, a holding temperature (sintering temperature) of 800°C, and a holding time (sintering time) of 2 hours. A pressure of 30 MPa was applied from the start of heating to the end of holding. After the holding time was completed, the sintered body was allowed to cool naturally in the chamber. Thereafter, the sintered body removed from the hot-pressing mold was subjected to HIP processing. The HIP processing conditions were a heating rate of 300°C / hour, a holding temperature of 750°C, and a holding time of 2 hours. The Ar gas pressure was gradually increased from the start of heating, and a pressure of 150 MPa was applied during the holding time. After the holding time was completed, the body was allowed to cool naturally in the furnace. In this way, a magnetic material target according to Example 1 was produced.

[0036] <Example 2> The magnetic material target according to Example 2 was manufactured by the following manufacturing method. As raw material powders, 3N (99.9 mass%) Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were prepared and weighed to have a composition of Co-Pt-Cr-BO (Pt 10-20 at%, Cr 0.5-7 at%, B 11-15 at%, O 16-26 at%, Co (balance)). The raw material powders were prepared so that the total composition was 100 at%. The 50% cumulative volume particle size D50 (average particle size D50) of the raw material powders was as follows: Co powder: 4μm, CrBO3 powder: 1μm, Pt powder: 3μm, Co2B2O5 powder: 8μm, Co2B powder: 30μm Next, the weighed Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were placed in a ball mill pot together with zirconia balls, and the mixture was subjected to primary mixing for 10 hours, sieving through a sieve with 150 μm openings, and secondary mixing for 10 hours, in that order.

[0037] Next, the mixed powder removed from the ball mill pot was filled into a carbon mold and hot-pressed. The hot-pressing conditions were a vacuum atmosphere, a heating rate of 300°C / hour, a holding temperature (sintering temperature) of 800°C, and a holding time (sintering time) of 2 hours. A pressure of 30 MPa was applied from the start of heating to the end of holding. After the holding time was completed, the sintered body was allowed to cool naturally in the chamber. Thereafter, the sintered body removed from the hot-pressing mold was subjected to HIP processing. The HIP processing conditions were a heating rate of 300°C / hour, a holding temperature of 750°C, and a holding time of 2 hours. The Ar gas pressure was gradually increased from the start of heating, and a pressure of 150 MPa was applied during the holding time. After the holding time was completed, the body was allowed to cool naturally in the furnace. In this way, a magnetic material target according to Example 2 was produced.

[0038] Example 3 The magnetic material target according to Example 3 was manufactured by the following manufacturing method. As raw material powders, 3N (99.9 mass%) Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were prepared and weighed to have a composition of Co-Pt-Cr-BO (Pt 10-20 at%, Cr 0.5-7 at%, B 11-15 at%, O 16-26 at%, Co (balance)). The raw material powders were prepared so that the total composition was 100 at%. The 50% cumulative volume particle size D50 (average particle size D50) of the raw material powders was as follows: Co powder: 4μm, CrBO3 powder: 1μm, Pt powder: 3μm, Co2B2O5 powder: 8μm, Co2B powder: 3μm Next, the weighed Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were placed in a ball mill pot together with zirconia balls, and the mixture was subjected to primary mixing for 8 hours, sieving through a sieve with 150 μm openings, and secondary mixing for 8 hours, in that order.

[0039] Next, the mixed powder removed from the ball mill pot was filled into a carbon mold and hot-pressed. The hot-pressing conditions were a vacuum atmosphere, a heating rate of 300°C / hour, a holding temperature (sintering temperature) of 800°C, and a holding time (sintering time) of 2.5 hours. A pressure of 30 MPa was applied from the start of heating to the end of the holding period. After the holding period, the sintered body was allowed to cool naturally in the chamber. Thereafter, the sintered body removed from the hot-pressing mold was subjected to HIP processing. The HIP processing conditions were a heating rate of 300°C / hour, a holding temperature of 750°C, and a holding time of 2 hours. The Ar gas pressure was gradually increased from the start of heating, and a pressure of 150 MPa was applied during the holding period. After the holding period, the sintered body was allowed to cool naturally in the furnace. In this way, a magnetic material target according to Example 3 was produced.

[0040] Example 4 The magnetic material target according to Example 4 was manufactured by the following manufacturing method. As raw material powders, 3N (99.9 mass%) Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were prepared and weighed to have a composition of Co-Pt-Cr-BO (Pt 10-20 at%, Cr 0.5-7 at%, B 11-15 at%, O 16-26 at%, Co (balance)). The raw material powders were prepared so that the total composition was 100 at%. The 50% cumulative volume particle size D50 (average particle size D50) of the raw material powders was as follows: Co powder: 4μm, CrBO3 powder: 1μm, Pt powder: 3μm, Co2B2O5 powder: 8μm, Co2B powder: 3μm Next, the weighed Co powder, CrBO3 powder, Pt powder, Co2B2O5 powder, and Co2B powder were placed in a ball mill pot together with zirconia balls, and the mixture was subjected to primary mixing for 10 hours, sieving through a sieve with 150 μm openings, and secondary mixing for 10 hours, in that order.

[0041] Next, the mixed powder removed from the ball mill pot was filled into a carbon mold and hot-pressed. The hot-pressing conditions were a vacuum atmosphere, a heating rate of 300°C / hour, a holding temperature (sintering temperature) of 750°C, and a holding time (sintering time) of 3 hours. A pressure of 30 MPa was applied from the start of heating to the end of holding. After the holding time was completed, the sintered body was allowed to cool naturally in the chamber. Thereafter, the sintered body removed from the hot-pressing mold was subjected to HIP processing. The HIP processing conditions were a heating rate of 300°C / hour, a holding temperature of 750°C, and a holding time of 2 hours. The Ar gas pressure was gradually increased from the start of heating, and a pressure of 150 MPa was applied during the holding time. After the holding time was completed, the body was allowed to cool naturally in the furnace. In this way, a magnetic material target according to Example 4 was produced.

[0042] <Comparative Example 1> A magnetic material target according to Comparative Example 1 was manufactured by the following manufacturing method. As raw material powders, 3N (99.9 mass%) Co powder, CrBO3 powder, Pt powder, and BO3 powder were prepared and weighed to have a composition of Co-Pt-Cr-BO (Pt 10-20 at%, Cr 0.5-7 at%, B 11-15 at%, O 16-26 at%, Co (balance)). The raw material powders were prepared so that the total composition was 100 at%. The 50% cumulative volume particle size D50 (average particle size D50) of the raw material powders was as follows: Co powder: 4μm, CrBO3 powder: 1μm, Pt powder: 3μm, B2O3 powder: 10μm Next, the weighed Co powder, CrBO3 powder, Pt powder, and B2O3 powder were placed in a ball mill pot together with zirconia balls, and the mixture was subjected to primary mixing for 12 hours, sieving through a sieve with 150 μm openings, and secondary mixing for 5 hours, in that order.

[0043] Next, the mixed powder removed from the ball mill pot was filled into a carbon mold and hot-pressed. The hot-pressing conditions were a vacuum atmosphere, a heating rate of 300°C / hour, a holding temperature (sintering temperature) of 800°C, and a holding time (sintering time) of 2 hours. A pressure of 30 MPa was applied from the start of heating to the end of holding. After the holding time was completed, the sintered body was allowed to cool naturally in the chamber. Thereafter, the sintered body removed from the hot-pressing mold was subjected to HIP processing. The HIP processing conditions were a heating rate of 300°C / hour, a holding temperature of 750°C, and a holding time of 2 hours. The Ar gas pressure was gradually increased from the start of heating, and a pressure of 150 MPa was applied during holding. After the holding time was completed, the sintered body was allowed to cool naturally in the furnace. In this way, a magnetic material target according to Comparative Example 1 was produced.

[0044] Observation field area: 11569 μm 2 Evaluation of the number of oxides with a given area per Each of the magnetic material targets of Examples 1 to 4 and Comparative Example 1 was cut and the cross section was mirror-polished to obtain a sample for observing the structure. Next, secondary electron images of the sputtered surfaces of the mirror-polished samples were taken using an FE-SEM (product name: SU3900, manufactured by Hitachi High-Technologies Corporation) at an accelerating voltage of 15 kV and a magnification of 1000. The taken SEM images are shown in Figure 3 (Example 1), Figure 4 (Example 2), Figure 5 (Example 3), Figure 6 (Example 4), and Figure 7 (Comparative Example 1), respectively. Next, the SEM image (field of view 11569 μm 2 The image was binarized by the mode method using image processing software (ImageJ manufactured by the National Institutes of Health), and the area of ​​each oxide was measured using the Analyze Particulates function of the image processing software. The particles (oxides) in the field of view were extracted, and the area of ​​each particle was calculated. 2 Oxide with an area of ​​more than 2.5 μm 2 Oxides with an area of ​​more than 2.0 μm 2 Oxides with an area of ​​more than 1.0 μm 2 Oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2The number of oxides having the following areas was counted. The ImageJ binarization was carried out according to the following steps (1) to (5). (1) Load an SEM image with a 1000x magnification from File → Open on the ImageJ toolbar. (2) Select 8-bit from Image → Type. Draw a line along the scale bar, and select Analyze → Set scale to set the scale size. (3) Select the part of the image excluding the scale and cut out the scale part by using Image → Crop. (4) Select Process → Filters → Gaussian Blur, enter 2 for Sigma, and click OK. (5) Select Process → Binary → Make Binary. This completes the binarization of the image. A screenshot of the setting conditions is shown in Figure 2. As described above, after importing the SEM image into ImageJ, a binarization process was performed to convert areas on the SEM image that were darker than the surrounding area, which were classified as black by the binarization process, into black, and the black areas were considered to be oxides. The area of ​​the black areas was calculated and the area was 3.0 μm 2 Oxide with an area of ​​more than 2.5 μm 2 Oxides with an area of ​​more than 2.0 μm 2 Oxides with an area of ​​more than 1.0 μm 2 Oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 The number of oxides having the following areas was counted. Based on the above measurement results, 1.0 μm 2 The number of oxides with an area of ​​more than 0.5 μm 2 Ultra~1.0μm 2 Divided by the number of oxides with an area of ​​0.5 μm 2 Ultra~1.0μm 2 The number of oxides with an area of ​​1.0 μm or less was counted. 2 The values ​​were calculated by dividing the area by the number of oxides having an area of ​​more than 1000 m.

[0045] A magnetic material target was manufactured using a composition and manufacturing method similar to those of Examples 1 to 4, and WDX mapping analysis was performed using FE-EPMA in a 50 μm × 50 μm field of view. The areas with high detection intensities for B and O were found to be consistent. This suggests that the magnetic material target contains an oxide of B. Therefore, the magnetic material targets of Examples 1 to 4, which are examples of targets manufactured using a composition and manufacturing method similar to those of the test example, are also expected to contain an oxide of B. Furthermore, since the raw material powder in Comparative Example 1 contains B2O3 powder, the magnetic material target of Comparative Example 1 is also expected to contain an oxide of B.

[0046] Particle evaluation The particle evaluation was carried out as follows. First, the magnetic material targets according to Examples 1 to 4 and Comparative Example 1 were machined on a lathe to form disk-shaped targets with a diameter of 165.1 mm and a thickness of 4.0 mm. These were attached to a magnetron sputtering device (Canon Anelva Corporation C-3010 sputtering system) and sputtering was carried out. The sputtering conditions were an input power of 1 kW and an Ar gas pressure of 1.7 Pa. After pre-sputtering at 1 kWhr, a film was formed on a 4-inch silicon substrate for 20 seconds. Next, for each of Examples 1 to 4, the number of particles with a particle size of 0.09 μm or larger adhering to the substrate was measured using a particle counter. A Candela CS920 (manufactured by KLA Tencor Corporation) was used as the particle counter. A laser was irradiated onto the wafer on which a film had been formed by sputtering, and particles were identified by detecting the reflection and scattering of the laser.

[0047] [Table 1]

[0048] <Consideration> According to Table 1, the magnetic material targets according to Examples 1 to 4 each contain Pt, Cr, B, and an oxide, with the balance being Co, the total concentration of Co, Pt, and Cr is 50 at% or more, the concentration of B is 9 at% or more, the concentration of O is 13.5 at% or more, and an oxide of B is contained, and the field area is 11569 μm 2 per 3.0μm 2 The number of oxides with an area of ​​more than 60 or less, 2.5 μm 2 The number of oxides with an area of ​​more than 2.0 μm is 100 or less. 2 The number of oxides with an area of ​​more than 1.0 μm is 150 or less, or 2 The number of oxides having an area of ​​more than 400 was less than 400. Therefore, the generation of particles during sputtering film formation was effectively suppressed. In contrast, the magnetic material target according to Comparative Example 1 had a field area of ​​11569 μm 2 per 3.0μm 2 The number of oxides with an area of ​​more than 60 and 2.5 μm 2 The number of oxides with an area of ​​more than 2.0 μm is more than 100. 2 The number of oxides with an area of ​​more than 1.0 μm is more than 150, or 2 The number of oxide particles each having an area of ​​more than 400 exceeded 400. As a result, it was not possible to suppress the generation of particles during sputtering film formation.

[0049] According to one embodiment of the present invention, a magnetic material target and a magnetic material target assembly containing oxides and mainly composed of Co, in which particle generation during sputtering film formation is effectively suppressed, can be obtained, which may contribute to the advancement of thin film formation technology by sputtering used in the manufacture of magnetic recording hard disk media, etc. Therefore, one embodiment of the present invention may contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation."

Claims

1. one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally contained impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B; Observation field area: 11569 μm 2 per 3.0 μm 2 The number of oxides having an area of ​​more than 60 is 60 or less.

2. one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally contained impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B; Observation field area: 11569 μm 2 per 2.5 μm 2 The number of oxides having an area of ​​more than 100 is 100 or less.

3. one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally contained impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B; Observation field area: 11569 μm 2 per 2.0 μm 2 The number of oxides having an area of ​​more than 150 is 150 or less.

4. one or more of Pt, Cr, Ru, B, and Ti; An oxide, and the balance is Co and optionally contained impurities, The total concentration of Co, Pt, Cr, Ru, and Ti is 50 at% or more, The concentration of B is 9 at% or more, and the concentration of O is 13.5 at% or more, the oxide comprises an oxide of B; Observation field area: 11569 μm 2 per 1.0 μm 2 The number of oxides having an area of ​​more than 400 is 400 or less.

5. 1.0 μm 2 The number of oxides having an area of ​​more than 0.5 μm 2 Super ~1.0μm 2 5. The magnetic material target according to claim 1, wherein a value obtained by dividing the area by the number of the oxides having the following area is 0.70 or less.

6. 0.5 μm 2 Super ~1.0μm 2 The number of oxides having an area of ​​1.0 μm or less was determined. 2 The magnetic material target according to any one of claims 1 to 4, wherein a value obtained by dividing the area by the number of said oxides having an area of ​​more than 1.5 is 1.5 or more.

7. The magnetic material target according to any one of claims 1 to 4, wherein the oxide further contains one or more oxides of elements selected from Al, Si, Ba, Be, Ca, Ce, Cr, Co, Dy, Er, Eu, Ga, Gd, Ho, Li, Mg, Mn, Nb, Nd, Pr, Sc, Sm, Sr, Ta, Tb, Ti, V, Y, Zn, and Zr.

8. The magnetic material target according to any one of claims 1 to 4, a backing plate bonded to the magnetic material target; 1. A magnetic material target assembly comprising:

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