Sputtering target and sputtering target assembly

Abstract

To provide a sputtering target capable of favorably suppressing occurrence of cracks and fractures during a manufacturing process.SOLUTION: A sputtering target having (1) Fe, (2) Pt, (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn, and (4) the remainder, the atomic ratio between (1) Fe and (2) Pt being 34-55 at%, the total concentration of (1) Fe and (2) Pt being 50 mol% or above, the total content of the elements (3) being 0.5-15 mol%, the remainder (4) being an oxide and optionally including impurities, the volume ratio of the oxide being 40 vol.% or more, and the number of oxide particles having a circle-equivalent diameter of 1 μm or less per measurement area of 1261 μm2 in a scanning electron microscope (SEM) photograph taken at a visual field magnification of 3000 being 100 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to sputtering targets and sputtering target assemblies, and primarily to sputtering targets for the production of films for HDDs. [Background technology]

[0002] The layers constituting 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, Co-Cr-Pt, or Fe-Pt alloy, with Co or Fe as the main component, and a non-magnetic inorganic material. Thin films for magnetic recording media such as hard disk drives are often produced by sputtering a sputtering target containing the above materials, due to their high productivity.

[0003] In general, sputtering targets are manufactured by first crushing 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 desired shape (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6030271 [Patent Document 2] Patent No. 6305881 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, a composite material composed of a ferromagnetic alloy such as an Fe-Pt alloy and a nonmagnetic inorganic material is useful as a recording layer for HDDs. However, when a sintered body having a structure in which oxides are dispersed in a base metal containing Fe and Pt is produced as a sputtering target for producing such a recording layer, the sintered body having this composition is relatively brittle, and there is a problem that cracks and breakage occur during the production process.

[0006] Therefore, an object of an embodiment of the present invention is to provide a sputtering target and a sputtering target assembly that can effectively suppress the occurrence of cracks and breakage during the manufacturing process. [Means for solving the problem]

[0007] The above problems are solved by the present invention, which is specified as follows. 1. A composition comprising: (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance; the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, the total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, the total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261 μm 2 A sputtering target having 100 or more oxide particles each having a circular equivalent diameter of 1 μm or less. 2. (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance. the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, the total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, the total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261 μm 2 The sputtering target has 120 or more particles per unit area, each particle having an equivalent circle diameter of 2 μm or less. 3. (1) Fe, (2) Pt, (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn, and (4) the balance; the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, the total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, the total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261 μm 2 A sputtering target in which the percentage of particles having an equivalent circular diameter of 1 μm or less per oxide is 60% or more. 4. (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance. the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, the total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, the total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261 μm 2 A sputtering target in which the percentage of oxide particles having a circular equivalent diameter of 2 μm or less per particle is 90% or more. 5. The sputtering target according to any one of 1 to 4 above, which has a bending strength of 300 MPa or more. 6. The sputtering target according to any one of 1 to 5 above, wherein the oxide contains an oxide of Si. 7. The sputtering target according to 6 above, wherein the oxide further contains one or more oxides of elements selected from Al, B, Ba, Be, Ca, Ce, Cr, Dy, Er, Eu, Ga, Gd, Ho, Li, Mg, Mn, Nb, Nd, Pr, Sc, Sm, Sr, Ta, Tb, Ti, V, Y, Zn, and Zr. 8. A sputtering target according to any one of 1 to 7 above, a backing plate bonded to the sputtering target; 1. A sputtering target assembly comprising: [Effects of the Invention]

[0008] According to the embodiments of the present invention, it is possible to provide a sputtering target and a sputtering target assembly that can effectively suppress the occurrence of cracks and breakage during the manufacturing process. [Brief explanation of the drawings]

[0009] [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. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that appropriate design changes, improvements, etc. may be made based on the common knowledge of those skilled in the art without departing from the spirit of the present invention. The multiple components disclosed in each embodiment can be appropriately combined to form various inventions. For example, some components may be omitted from all the components shown in each embodiment, or components from different embodiments may be appropriately combined.

[0011] <Sputtering target> The shape of the sputtering 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.

[0012] A sputtering target according to an embodiment of the present invention comprises (1) Fe, (2) Pt, (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn, and (4) the balance. The balance in (4) is an oxide and may selectively contain impurities. The sputtering target according to an embodiment of the present invention comprises a metal phase containing ferromagnetic materials Fe and Pt, and a phase other than the metal phase containing an oxide, and can function as a magnetic thin film.

[0013] In the sputtering target according to the embodiment of the present invention, the atomic ratio of Fe to Pt is 34 to 55 at %. That is, the atomic ratio of Fe to Pt in the sputtering target is as follows: 100-X Pt XIn this case, X satisfies the relationship 34≦X≦55. When the Fe and Pt in the sputtering target satisfy this atomic ratio, the function as a magnetic thin film is improved. The atomic ratio of Fe to Pt is preferably 40≦X≦53, and more preferably 44≦X≦51.

[0014] The sputtering target according to an embodiment of the present invention has a total concentration of Fe and Pt of 50 mol% or more. When the total concentration of Fe and Pt in the sputtering target is 50 mol% or more, the magnetic properties are improved. There is no particular upper limit to the total concentration of Fe and Pt, but from the viewpoint of ensuring grain boundary material, it is preferably 80 mol% or less. Furthermore, the total concentration of Fe and Pt is more preferably 50 to 75 mol%, and even more preferably 50 to 70 mol%.

[0015] A sputtering target according to an embodiment of the present invention contains one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn in a total content of 0.5 to 15 mol%. These elements, along with Fe and Pt, are components of the metal phase, and containing 0.5 to 15 mol% further improves the magnetic properties of a sputtering target primarily composed of Fe and Pt. The content of these elements is more preferably 2 to 13 mol%, and even more preferably 4 to 11 mol%.

[0016] The sputtering target according to an embodiment of the present invention may contain, as the remainder, an oxide and may selectively contain impurities. A particularly preferable magnetic thin film can be obtained by using SiO2 as the oxide. Furthermore, in addition to SiO2, the oxide may further contain one or more oxides of elements selected from Al, B, Ba, Be, Ca, Ce, Cr, Dy, Er, Eu, Ga, Gd, Ho, Li, Mg, Mn, Nb, Nd, Pr, Sc, Sm, Sr, Ta, Tb, Ti, V, Y, Zn, and Zr to further improve magnetic properties.

[0017] The sputtering target according to the embodiment of the present invention has an oxide volume fraction of 40 vol.% or more. When the oxide volume fraction in the sputtering target is 40 vol.% or more, the magnetic properties are further improved. There is no particular upper limit to the oxide volume fraction in the sputtering target, but from the viewpoint that an excessive amount of oxide deteriorates the magnetic properties, it is preferably 60 vol.% or less. Furthermore, the oxide volume fraction in the sputtering target is more preferably 40 to 55 vol.%, and even more preferably 40 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 multiplying the volume of each component 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] Impurities selectively contained in the remainder of the sputtering target according to the embodiment of the present invention include metal elements not included in the elements (1) to (3) above, and simple substances or compounds of elements such as C or N from gas components such as carbon dioxide and nitrogen in the atmosphere. The content of the impurities selectively contained in the remainder of the sputtering target according to the embodiment of the present invention may be 0.5 mol% or less, or may be 0.15 mol% or less. Furthermore, impurities can be analyzed by collecting an analytical sample from the sputtering target and using infrared absorption spectroscopy, an ICP optical emission spectrometer, GDMS (glow discharge mass spectrometry), or the like. 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] In one aspect, a sputtering target according to an embodiment of the present invention has a measured area of ​​1261 μm in a scanning electron microscope (SEM) photograph taken at a field magnification of 3000 times. 2 The number of particles with an equivalent circular diameter of 1 μm or less per measurement area is 100 or more. 2When the number of oxide particles with an equivalent circular diameter of 1 μm or less per target is 100 or more, the oxide structure is fine, and the sputtering target has good strength. The fine, dispersed oxide structure results in a complex structure of oxide phases and phases containing Fe and Pt. Even if minute defects that could develop into cracks occur, the boundary between the oxide phase and the phase containing Fe and Pt acts as a barrier to prevent the defects from developing, thereby preventing the defects from becoming cracks or fractures. Therefore, during the sputtering target manufacturing process, the raw material powders are crushed and mixed to obtain a mixture, and then the mixture is subjected to hot pressing, followed by HIP processing to increase the density of the sintered compact, which effectively prevents the occurrence of cracks or fractures. The measurement area is 1261 μm. 2 The number of particles having an oxide equivalent circle diameter of 1 μm or less per measurement area is preferably 120 or more, more preferably 140 or more, more preferably 160 or more, more preferably 180 or more, more preferably 200 or more, and more preferably 220 or more. 2 There is no particular need to limit the upper limit of the number of particles having an oxide equivalent circle diameter of 1 μm or less per particle, but it may be, for example, 600 or less, for example, 580 or less, for example, 560 or less, for example, 540 or less, for example, 520 or less, or for example, 500 or less.

[0020] In another aspect, the sputtering target according to the present invention has a measured area of ​​1261 μm in a scanning electron microscope (SEM) photograph taken at a field magnification of 3000 times. 2 The number of particles with an equivalent circular diameter of 2 μm or less per measurement area is 120 or more. 2When the number of oxide particles with an equivalent circle diameter of 2 μm or less per target is 120 or more, the oxide structure is refined, and the sputtering target has good strength. The refined and dispersed oxide structure results in a complex structure of oxide phases and phases containing Fe and Pt. Even if minute defects that could develop into cracks occur, the boundary between the oxide phase and the phase containing Fe and Pt acts as a barrier to prevent the defects from developing, thereby preventing the defects from becoming cracks or fractures. Therefore, during the manufacturing process of a sputtering target, the occurrence of cracks or fractures can be effectively prevented during hot pressing of the mixture obtained by pulverizing and mixing raw material powders, and further during subsequent HIP processing to increase the density of the sintered compact. The measurement area is 1261 μm. 2 The number of particles having an oxide equivalent circle diameter of 2 μm or less per measurement area is preferably 140 or more, more preferably 160 or more, more preferably 180 or more, more preferably 200 or more, more preferably 220 or more, and more preferably 240 or more. 2 There is no particular need to limit the upper limit of the number of particles having an oxide equivalent circle diameter of 2 μm or less per particle, but it may be, for example, 640 or less, for example, 620 or less, for example, 600 or less, for example, 580 or less, or for example, 560 or less.

[0021] A scanning electron microscope (SEM) photograph of the sputtering target according to the embodiment of the present invention taken at a magnification of 3000 times shows a measured area of ​​1261 μm 2 This section describes in detail the method for measuring the number of particles of oxides with equivalent circular diameters of 1 μm or less and 2 μm or less. First, the sputtering target is cut and the cross section is mirror-polished to prepare an SEM observation sample. Next, the SEM observation sample is observed using, for example, an SEM (S-3700N, manufactured by Hitachi High-Technologies Corporation). The observation settings are as follows: Image: Secondary electron image, Field of view magnification: 3000x, Acceleration voltage: 10-15kV 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 captured SEM image is binarized by the mode method using image processing software (ImageJ, manufactured by the National Institutes of Health), and the area of ​​each oxide is measured using the AnalyzeParticles function of the image processing software. The area S of each oxide in the oxide phase obtained in this way is used to calculate the diameter D of each oxide using the following formula (1). The diameter D is taken as the equivalent circle diameter of the oxide, and the number of particles with equivalent circle diameters of 1 μm or less and 2 μm or less is counted.

[0022] JPEG2025167932000002.jpg10148

[0023] The ImageJ binarization is performed according to the following steps (1) to (7). (1) Load an SEM image with a magnification of 3000x 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. (6) Select Analyze → Set measurement and check Area. (7) Select Analyze → Analyze Particle, set the analysis conditions to Size: 0-infinity, Circularity: 0.00-1.00, Show: nothing, check Summarize, and select OK. This will display the results, where the area S of each oxide in the oxide phase will be measured. As described above, the areas that are darker than the surrounding areas that are classified as black by the binarization process are converted to black, and the black areas are considered to be oxides. The threshold value for the binarization process is automatically set based on the color histogram in the image. Figure 1 shows an example of the binarized image and the original image.

[0024] In yet another aspect, the sputtering target according to the present invention has a measurement area of ​​1261 μm in a scanning electron microscope (SEM) photograph taken at a field magnification of 3000 times. 2 The percentage of particles with a circular equivalent diameter of 1 μm or less is 60% or more. 2 When the proportion of oxide particles with an equivalent circular diameter of 1 μm or less per particle is 60% or more, the oxide structure is refined, and the sputtering target has good strength. The refined and dispersed oxide structure results in a complex structure of oxide phases and phases containing Fe and Pt. Even if minute defects that could develop into cracks occur, the boundary between the oxide phase and the phase containing Fe and Pt acts as a barrier to prevent the defects from developing, thereby preventing the defects from becoming cracks or fractures. Therefore, during the manufacturing process of a sputtering target, the occurrence of cracks or fractures can be effectively prevented during hot pressing of the mixture obtained by pulverizing and mixing raw material powders, and further during subsequent HIP processing to increase the density of the sintered compact. The measurement area is 1261 μm. 2The percentage of particles having an oxide equivalent circular diameter of 1 μm or less per measurement area is preferably 61.5% or more, more preferably 63% or more, more preferably 65% ​​or more, more preferably 67% or more, more preferably 68% or more, and more preferably 69% or more. 2 The upper limit of the number ratio of particles having an oxide equivalent circular diameter of 1 μm or less per particle does not need to be particularly limited, but may be, for example, 89.8% or less, for example, 87.5% or less, for example, 86% or less, for example, 85% or less, for example, 84% or less, or for example, 83.4% or less.

[0025] In yet another aspect, the sputtering target according to the present invention has a measurement area of ​​1261 μm in a scanning electron microscope (SEM) photograph taken at a field magnification of 3000 times. 2 The percentage of particles with an equivalent circular diameter of 2 μm or less per measurement area is 90% or more. 2 When the proportion of oxide particles with an equivalent circular diameter of 2 μm or less per particle is 90% or more, the oxide structure is refined, and the sputtering target has good strength. The refined and dispersed oxide structure results in a complex structure of oxide phases and phases containing Fe and Pt. Even if minute defects that could develop into cracks occur, the boundary between the oxide phase and the phase containing Fe and Pt acts as a barrier to prevent the defects from developing, thereby preventing the defects from becoming cracks or fractures. Therefore, during the sputtering target manufacturing process, the raw material powders are crushed and mixed to obtain a mixture, and then the mixture is subjected to hot pressing, followed by HIP processing to increase the density of the sintered compact. The measurement area is 1261 μm. 2The percentage of particles having an oxide equivalent circular diameter of 2 μm or less per measurement area is preferably 90.5% or more, more preferably 91% or more, more preferably 91.5% or more, more preferably 92% or more, more preferably 92.5% or more, and more preferably 93% or more. 2 The upper limit of the number ratio of particles having an oxide equivalent circular diameter of 2 μm or less per particle does not need to be particularly limited, but may be, for example, 98% or less, for example, 97% or less, for example, 96% or less, for example, 95% or less, or for example, 94% or less.

[0026] A scanning electron microscope (SEM) photograph of the sputtering target according to the embodiment of the present invention taken at a magnification of 3000 times shows a measured area of ​​1261 μm 2 This section describes in detail the method for measuring the proportion of particles with an equivalent circular diameter of oxide of 1 μm or less and 2 μm or less per unit area. First, the measurement area of ​​the above SEM photograph is 1261 μm 2 The number of particles having an equivalent circle diameter of 1 μm or less and 2 μm or less per 1261 μm area of ​​the SEM photograph is calculated in the same manner as in the measurement of the number of particles having an equivalent circle diameter of 1 μm or less and 2 μm or less per 1261 μm area of ​​the SEM photograph. 2 The particle diameter is evaluated by calculating the percentage (%) of the number of particles having the above-mentioned equivalent circle diameter of 1 μm or less and 2 μm or less to the total number of particles measured in the above.

[0027] The sputtering target according to the embodiment of the present invention preferably has a bending strength of 300 MPa or more. When the bending strength is 300 MPa or more, the occurrence of cracks and breakage during the manufacturing process can be more effectively suppressed. The sputtering target according to the embodiment of the present invention more preferably has a bending strength of 350 MPa or more.

[0028] The bending strength of the sputtering target according to the embodiment of the present invention can be measured as follows. First, seven test pieces are prepared by cutting out the sputtering target. As a specific example of the cutting method, the sputtering target is machined to a thickness of 3 mm using a lathe, and then cut into pieces measuring 4 mm x 35 mm using electrical discharge wire machining. Since the surface is oxidized, the surface is polished with #120 abrasive paper to remove the oxide film and prepare the sample. Next, the three-point bending strength of the test piece is measured under the following measurement conditions, and the average value is taken as the bending strength of the sputtering target. <Measurement conditions> A benchtop material testing machine (STB-1225S) manufactured by A&D Corporation can be used as the measuring device. Measurement of the bending strength of the sputtering target according to the embodiment of the present invention can be performed with reference to JIS R 1601:2008, "Test Method for Bending Strength of Fine Ceramics." Table 1 shows the conditions for measuring the bending strength of the sputtering target according to the embodiment of the present invention and the conditions for measuring bending strength specified in JIS R 1601:2008. As shown in Table 1, the conditions for measuring the bending strength of the sputtering target according to the embodiment of the present invention differ from the conditions for measuring bending strength specified in JIS R 1601:2008 only with respect to the "radius of curvature of the support," "test piece length," "parallelism," "edge of the test piece," "roughness Ra of the test piece," and "number of test pieces."

[0029] [Table 1]

[0030] A sputtering target according to an embodiment of the present invention may be: (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance, the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, the total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, the total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, A sputtering target that satisfies one, two, three, or four of the following items A to D. A: Scanning electron microscope (SEM) photograph taken at a magnification of 3000x, measuring area 1261 μm 2 The number of particles of the oxide having a circular equivalent diameter of 1 μm or less is 100 or more. B: Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261 μm 2 The number of particles of the oxide having a circular equivalent diameter of 2 μm or less is 120 or more. C: Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261 μm 2 The proportion of particles with an equivalent circular diameter of 1 μm or less per oxide is 60% or more. D: Scanning electron microscope (SEM) photograph taken at a magnification of 3000x, measuring area 1261 μm 2 The proportion of particles with an equivalent circular diameter of oxide of 2 μm or less per unit area is 90% or more.

[0031] <Sputtering target assembly> The sputtering target according to the embodiment of the present invention may be bonded to a backing plate as needed to form a sputtering target assembly. The sputtering target assembly can be mounted in a sputtering apparatus for use. Indium or indium tin can be used as the brazing material. The sputtering 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). The material of the backing plate preferably has high thermal conductivity, and from this perspective, Cu is suitable.

[0032] <Method for manufacturing sputtering targets> A method for producing a sputtering target according to an embodiment of the present invention will be described in detail below. The sputtering target according to the embodiment of the present invention can be produced by a powder sintering method. First, powders of the respective metal elements are prepared. Alternatively, alloy powders of these metals (e.g., Fe-Pt powder) may be used instead of the powders of the respective metal elements. 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 compact will contain a large amount of impurities, which may result in problems such as the failure to obtain the desired physical properties (e.g., generation of particles due to arcing). These raw materials can be appropriately prepared based on the composition and purity of the desired sintered compact.

[0033] 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 in an inert gas atmosphere or in a vacuum. The mixing time is set to 0.1 to 48 hours. By extending the mixing time of the raw materials, the measured area of ​​1261 μm in a scanning electron microscope (SEM) photograph taken at a field magnification of 3000 times can be increased. 2 The number or percentage of particles with an oxide equivalent circle diameter of 1 μm or less per unit area can be increased by shortening the mixing time of the raw materials. On the other hand, the measured area of ​​1261 μm in a scanning electron microscope (SEM) photograph taken at a magnification of 3000 times can be reduced by shortening the mixing time of the raw materials. 2 From this perspective, by adjusting the mixing time of the raw materials, it is possible to reduce the number or proportion of particles with an oxide equivalent circle diameter of 1 μm or less per unit area. 2 The number or proportion of particles having an oxide equivalent circle diameter of 1 μm or less or 2 μm or less per particle is controlled.

[0034] 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. If the sintering temperature is increased and / or the sintering time is extended, a sintered body with a measured area of ​​1261 μm2 can be obtained in a scanning electron microscope (SEM) photograph taken at a magnification of 3000 times. 2 On the other hand, if the sintering temperature is lowered and / or the sintering time is shortened, the number or proportion of particles having an oxide equivalent circle diameter of 1 μm or less per unit area can be increased. 2From this perspective, by adjusting the sintering temperature and sintering time, it is possible to reduce the number or percentage of particles with an oxide equivalent circle diameter of 1 μm or less per unit area. 2 The number or proportion of particles having an oxide equivalent circle diameter of 1 μm or less or 2 μm or less per particle is controlled.

[0035] 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 sputtering target.

[0036] <Film formation method using sputtering targets> The sputtering 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 sputtering target with accelerated argon ions, releasing particles (sputtered particles) from the sputtering target, and depositing the sputtered particles on the surface of a substrate previously positioned opposite the sputtering 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]

[0037] The following examples of the present invention are provided for a better understanding of the present invention and its advantages, but are not intended to limit the invention.

[0038] Example 1 The sputtering target according to Example 1 was manufactured by the following manufacturing method. Fe powder, Pt powder, Ag powder, and SiO2 powder were prepared as raw material powders and weighed out to have a composition of (30-45)Fe-(30-45)Pt-(5-15)Ag-(5-25)SiO2 (mol%). The raw material powders were adjusted so that the total composition was 100 mol%. Amorphous SiO2 powder was used. Next, the weighed Fe powder, Pt powder, Ag powder, and SiO2 powder were placed in a 5 L ball mill pot along with zirconia balls and mixed for 4 hours.

[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 900°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 850°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 sputtering target according to Example 1 was produced.

[0040] <Examples 2 to 8, Comparative Example 1> The sputtering targets according to Examples 2 to 8 and Comparative Example 1 were produced in the same manner as in Example 1. The mixing time of the raw material powders, the hot pressing temperature, and the HIP holding temperature were set under the conditions shown in Table 2.

[0041] Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261μm 2 The number of particles with an oxide equivalent circle diameter of 1 μm or less or 2 μm per particle First, the sputtering target was cut and the cross section was mirror-polished to prepare an SEM observation sample. Next, the SEM observation sample was observed using an SEM (S-3700N, manufactured by Hitachi High-Technologies Corporation). The observation settings were as follows: Image: Secondary electron image, Field of view magnification: 3000x, Acceleration voltage: 10-15kV 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 captured SEM images were 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 AnalyzeParticles function of the image processing software. The diameter D of each oxide in the oxide phase obtained in this way was calculated using the following formula (1). The diameter D was defined as the equivalent circle diameter of the oxide, and the number of particles with an equivalent circle diameter of 1 μm or less or 2 μm or less was counted.

[0042] JPEG2025167932000004.jpg10148

[0043] The above ImageJ binarization was carried out according to the following steps (1) to (7). (1) Load an SEM image with a magnification of 3000x 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. (6) Select Analyze → Set measurement and check Area. (7) Select Analyze → Analyze Particle, set the analysis conditions to Size: 0-infinity, Circularity: 0.00-1.00, Show: nothing, check Summarize, and select OK. This will display the results, where the area S of each oxide in the oxide phase will be measured. As described above, the areas that were darker than the surrounding areas and classified as black by the binarization process were converted to black, and the black areas were considered to be oxides. The threshold value for the binarization process was automatically set based on the color histogram in the image.

[0044] Scanning electron microscope (SEM) photograph taken at 3000x magnification, measuring area 1261μm 2 Percentage of particles with an oxide equivalent circle diameter of 1 μm or less or 2 μm or less per particle First, the measurement area of ​​the above SEM photograph is 1261 μm 2 The number of particles with an equivalent circle diameter of 1 μm or less or 2 μm or less per 1261 μm area was calculated in the same manner as in the measurement of the number of particles with an equivalent circle diameter of 1 μm or less or 2 μm or less per 1261 μm area. 2 The particle diameter was evaluated by calculating the percentages (%) of the number of particles having the above-mentioned equivalent circle diameter of 1 μm or less and 2 μm or less to the total number of particles measured in the above.

[0045] Oxide volume ratio The oxide volume fraction was evaluated by calculating the volume of each component contained in the target as follows: (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 was calculated by dividing the total volume of oxides by the total volume of all components.

[0046] Bending strength Seven test pieces were prepared by cutting out a sample of the sputtering target. The sputtering target was machined to a thickness of 3 mm using a lathe, and then cut into pieces measuring 4 mm x 35 mm using electrical discharge wire machining. Next, since the surface was oxidized, the surface was polished with #120 abrasive paper to remove the oxide film, and the sample was prepared. Next, the three-point bending strength was measured under the following measurement conditions, and the average value was taken as the bending strength of the sputtering target. Note that the bending strength test was not carried out for Examples 3 to 8. <Measurement conditions> A benchtop material testing machine (STB-1225S) manufactured by A&D Corporation was used as the measuring device. The bending strength of the sputtering target according to this test example was measured with reference to JIS R 1601:2008 "Test method for bending strength of fine ceramics," and was carried out under the "measurement conditions of this embodiment" shown in Table 1 above. That is, as shown in Table 1 above, the measurement conditions for the bending strength of the sputtering target according to this test example differ from the bending strength measurement conditions described in JIS R 1601:2008 only for the "radius of curvature of the support," "test piece length," "parallelism," "edge of the test piece," "roughness Ra of the test piece," and "number of test pieces."

[0047] Cracks The surface of each of the sputtering targets of the examples and comparative examples was visually inspected to determine whether or not any cracks were present. Based on this evaluation, it was determined whether or not the occurrence of cracks or breakage during the manufacturing process was suppressed. The evaluation results are shown in Table 2.

[0048] [Table 2]

[0049] <Consideration> According to Table 2, the sputtering targets according to Examples 1 to 8 each contained (1) Fe, (2) Pt, (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn, and (4) the balance, in which the atomic ratio of (1) Fe to (2) Pt was 34 to 55 at %, the total concentration of (1) Fe and (2) Pt was 50 mol % or more, the total content of (3) element was 0.5 to 15 mol %, the balance of (4) was an oxide, and the volume fraction of the oxide was 40 vol % or more. Furthermore, a scanning electron microscope (SEM) photograph taken at a magnification of 3000x showed a measured area of ​​1261 μm 2 The number of particles with an equivalent circular diameter of 1 μm or less per unit area was 100 or more. 2 The number of particles with an equivalent circular diameter of 2 μm or less per unit area was 120 or more. 2 The percentage of particles with an oxide equivalent circle diameter of 1 μm or less per unit area was 60% or more. 2 The percentage of particles with an equivalent circular diameter of 2 μm or less per oxide was 90% or more. This resulted in good bending strength and suppressed the occurrence of cracks and breakage during the manufacturing process. In contrast, in Comparative Example 1, the measurement area of ​​the scanning electron microscope (SEM) photograph taken at a visual field magnification of 3000 times was 1261 μm 2 The number of particles with an oxide equivalent circle diameter of 1 μm or less per unit area is less than 100, and the measurement area of ​​a scanning electron microscope (SEM) photograph taken at a magnification of 3000x is 1261 μm. 2 The number of particles with an oxide equivalent circle diameter of 2 μm or less per unit area is less than 120, and the measurement area of ​​a scanning electron microscope (SEM) photograph taken at a magnification of 3000x is 1261 μm 2The percentage of particles with an oxide equivalent circle diameter of 1 μm or less per unit area is less than 60%, and the measurement area of ​​a scanning electron microscope (SEM) photograph taken at a magnification of 3000x is 1261 μm 2 The percentage of particles with an equivalent circular diameter of 2 μm or less per oxide was less than 90%, which resulted in poor bending strength and the occurrence of cracks and breakage during the manufacturing process.

[0050] According to one embodiment of the present invention, a sputtering target and a sputtering target assembly can be obtained that can effectively suppress the occurrence of cracks and breakages during the manufacturing process, which may contribute to the advancement of thin-film formation technology by sputtering used in the manufacture of 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. (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance, the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, The total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, The total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at a magnification of 3000 times shows a measurement area of ​​1261 μm 2 A sputtering target having 100 or more oxide particles each having an equivalent circle diameter of 1 μm or less.

2. (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance, the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, The total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, The total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at a magnification of 3000 times shows a measurement area of ​​1261 μm 2 A sputtering target having 120 or more oxide particles each having a circular equivalent diameter of 2 μm or less.

3. (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance, the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, The total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, The total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at a magnification of 3000 times shows a measurement area of ​​1261 μm 2 A sputtering target in which the proportion of particles having an equivalent circle diameter of 1 μm or less per oxide is 60% or more.

4. (1) Fe; (2) Pt; (3) one or more elements selected from Ag, Au, B, Co, Cr, Cu, Ga, Ge, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Si, Sn, Ta, W, V, and Zn; and (4) the balance, the atomic ratio of the (1) Fe to the (2) Pt is 34 to 55 at %, The total concentration of the (1) Fe and the (2) Pt is 50 mol% or more, The total content of the element (3) is 0.5 to 15 mol%, The remainder of the (4) is an oxide, which may selectively contain impurities, and the volume fraction of the oxide is 40 vol.% or more, Scanning electron microscope (SEM) photograph taken at a magnification of 3000 times shows a measurement area of ​​1261 μm 2 A sputtering target in which the proportion of particles having an equivalent circle diameter of oxide of 2 μm or less per particle is 90% or more.

5. The sputtering target according to any one of claims 1 to 4, having a bending strength of 300 MPa or more.

6. The sputtering target according to any one of claims 1 to 4, wherein the oxide contains an oxide of Si.

7. 7. The sputtering target according to claim 6, wherein the oxide further contains one or more oxides of elements selected from Al, B, Ba, Be, Ca, Ce, Cr, 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 sputtering target according to any one of claims 1 to 4, a backing plate bonded to the sputtering target; 1. A sputtering target assembly comprising:

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