Target and method for producing same

Abstract

The purpose of the present disclosure is to provide means for efficiently forming a thin film when forming a thin film by a sputtering method. In one aspect, the present disclosure encompasses the following invention.　This target comprises Co, Ta, and Zr, and has a maximum magnetic permeability of 8 or less.

Description

Target and manufacturing method thereof The present disclosure relates to a target and a manufacturing method thereof. Specifically, the present disclosure relates to a target made of Co, Ta, and Zr and a manufacturing method thereof. Targets made of Co, Ta, and Zr are often used to form magnetic thin films. For example, a Co alloy target is used to form a soft magnetic film that constitutes a magnetic medium. Patent Document 1 discloses a method for producing a Co alloy target material, specifically, by rapidly solidifying a molten Co alloy to produce alloy powder, and then pressure-sintering the alloy powder having a particle size of 500 μm or less. Patent Document 2 discloses a Co—Zr alloy sintered sputtering target material. Specifically, Patent Document 2 discloses that powder produced by gas atomization is classified, and then a sintered body is produced from the powder by hot isostatic pressing. Patent Document 3 discloses a sputtering target that is a ternary or higher alloy containing Co as a main component. Specifically, Patent Document 3 discloses that powder is produced by a gas atomization method, and then a sintered body is produced from the powder by a plasma sintering method. JP 2005-320627 A JP 2008-260970 A JP 2009-263796 A The magnetism of a sputtering target affects sputtering efficiency. The present disclosure aims to provide a means for efficiently forming a thin film by sputtering. In order to achieve the above object, the present disclosure provides, in one aspect, the following invention. (Invention 1) A target consisting of Co, Ta, and Zr, The structure of the target includes a Co phase and an intermetallic compound phase, A target having an average number Z of boundaries between adjacent phases of 15<Z when measured under the following conditions: ・Obtaining tissue images through SEM Draw five straight lines (L1 to L5) with a length of 40 μm, parallel to each other and spaced 10 μm apart. Count the number of boundaries (N1 to N5) between adjacent phases on each line (L1 to L5). ・Calculate the average number Z of each boundary number (N1 to N5). (Invention 2) The target of Invention 1, wherein the average number α of the intermetallic compound phases on the straight lines (L1 to L5) is 5<α<10. (Invention 3) The target according to any one of inventions 1 and 2, wherein the maximum magnetic permeability is 8 or less. (Invention 4) The target according to any one of Inventions 1 to 3, wherein when analyzed by X-ray diffraction, the following peaks are present: Base peaks from FCC-Co and / or HCP-Co phases, CoZr2 phase and / or Co2(Ta 0.5 Zr 0.5 ) phase-derived first peak, ・CoZr2 phase, Co 23 a second peak derived from at least one phase selected from the group consisting of a Zr phase and a CoTa phase; ・FCC-Co phase, HCP-Co phase, Co 23 A third peak derived from at least one phase selected from the group consisting of a Zr phase and a CoTa phase; and - A fourth peak derived from the CoTa phase, an intensity ratio of the first peak, the second peak, the third peak, and the fourth peak to the base peak is 0.8 or more; target. (Invention 5) A target according to invention 4, When analyzed by X-ray diffraction, a fifth peak derived from the Ta phase is present, an intensity ratio of the fifth peak to the base peak is 0.8 or more; target. (Invention 6) A target consisting of Co, Ta, and Zr, The structure of the target includes a Co phase and an intermetallic compound phase, When analyzed by X-ray diffraction, the following peaks are present: Base peaks from FCC-Co and / or HCP-Co phases, CoZr2 phase and / or Co2(Ta 0.5 Zr 0.5 ) phase-derived first peak, ・CoZr2 phase, Co 23 a second peak derived from at least one phase selected from the group consisting of a Zr phase and a CoTa phase; ・FCC-Co phase, HCP-Co phase, Co 23 A third peak derived from at least one phase selected from the group consisting of a Zr phase and a CoTa phase; and ・Fourth peak derived from Co2Ta phase an intensity ratio of the first peak, the second peak, the third peak, and the fourth peak to the base peak is 0.8 or more; target. (Invention 7) A target according to Invention 6, When analyzed by X-ray diffraction, a fifth peak derived from the Ta phase is present, an intensity ratio of the fifth peak to the base peak is 0.8 or more; target. (Invention 8) A target consisting of Co, Ta, and Zr, A target having a maximum magnetic permeability of 8 or less. (Invention 9) 1. A method for producing a target comprising Co, Ta, and Zr, the method comprising: - A step of preparing powder consisting of Co, Ta, and Zr by atomization; - a step of preparing a sintered body from the powder by hot pressing; Including, The step of preparing the powder includes adjusting the particle size distribution to satisfy the following conditions: ・D(10)v: 20-40μm ・D(50)v: 90-140μm ・D(90)v: 200-330μm The step of preparing the sintered body includes hot pressing under the following conditions: Temperature: 1100-1200℃, Holding time: 3 to 6 hours Pressure: 100 to 300 kgf / cm 2 method. In one aspect of the present disclosure, the average number Z of boundaries between adjacent phases is 15<Z. This indicates that the Co phase is refined. This reduces the maximum magnetic permeability of the target, and improves sputtering efficiency. In another aspect of the present disclosure, the target structure suggests the presence of various intermetallic compound phases. At least a CoTa phase is present. Intermetallic compound phases tend to have higher melting points than Co alone. Therefore, the growth of the Co phase is hindered, allowing the Co phase to be refined. This reduces the maximum magnetic permeability of the target. Consequently, sputtering efficiency is improved. In yet another aspect of the present disclosure, the maximum magnetic permeability of the target is 8 or less. That is, the maximum magnetic permeability is kept extremely low. This improves sputtering efficiency. 1 shows a photograph of the structure of a target observed by SEM in the prior art. In one embodiment, a method for counting the number of linear boundaries and the number of intermetallic compound phases in a photograph observed by SEM is shown. The figure schematically shows the Co phase and intermetallic compound phases M1 to M3, with the boundaries between them indicated by black dots. In one embodiment, a photograph of the structure (center) of a target of the present disclosure observed by SEM is shown. Five lines and multiple black dots highlighting the boundaries are shown in the photograph. In one embodiment, a photograph of the structure (1 / 2R) of a target of the present disclosure observed by SEM is shown. Five lines and multiple black dots highlighting the boundaries are shown in the photograph. In one embodiment, a photograph of the structure (periphery) of a target of the present disclosure observed by SEM is shown. Five lines and multiple black dots highlighting the boundaries are shown in the photograph. In one embodiment, a photograph of the structure (periphery) of a target of the present disclosure observed by SEM is shown. Five lines and multiple black dots highlighting the boundaries are shown in the photograph. In one embodiment, the results of X-ray diffraction analysis of a target of the present disclosure are shown. Specific embodiments for carrying out the present invention will be described below. The following description is intended to facilitate understanding of the invention and is not intended to limit the scope of the present invention. 1. Target In one embodiment, the present disclosure relates to a target. The target is a material used in a sputtering method to form a thin film. When released as a product, the target may be used with a backing plate to form a sputtering target assembly, if necessary. An insert material may also be provided between the target and the backing plate to promote bonding between them. The composition and shape of the backing plate and insert material are not particularly limited, and may be of a known composition and shape. 1-1. composition The target is composed of Co, Ta, and Zr (in other words, the elements constituting the target are Co, Ta, and Zr). However, the target composition does not exclude the inclusion of unavoidable impurities. The contents of Co, Ta, and Zr are not particularly limited, but of these three elements, the content (atomic %) of Co is the highest. Although not limited thereto, the combination of the contents of Co, Ta, and Zr may be in the following ranges. Co: 50 to 98 atomic % (preferably 80 atomic % or more and / or 95 atomic % or less) Ta: 1 to 25 atomic % (preferably, 2.5 atomic % or more and / or 10 atomic % or less) Zr: 1 to 25 atomic % (preferably, 2.5 atomic % or more and / or 10 atomic % or less) Examples of unavoidable impurities include, but are not limited to, the following elements: Li, Be, B, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Th, U, C, O, N, and H. Although not limited thereto, the amount of unavoidable impurities is 1300 ppm by mass or less, preferably 800 ppm by mass or less, as the total amount of the above-mentioned elements. The lower limit is not particularly limited, but may be 0 ppm by mass or more. In a specific embodiment, the inevitable impurities of the gas include C, O, N, and H. The total amount of the inevitable impurities of these gases is 800 ppm by mass or less, preferably 500 ppm by mass or less. The lower limit is not particularly limited, but may be 0 ppm by mass or more. In certain embodiments, metal-based unavoidable impurities include the following elements: Li, Be, B, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Th, and U. The total amount of these metallic unavoidable impurities is 500 mass ppm or less, preferably 300 mass ppm or less, and more preferably 100 mass ppm or less. The lower limit is not particularly limited, but may be 0 mass ppm or more. In this specification, S and Si are listed as examples of metallic unavoidable impurities, but for convenience, the term "metallic unavoidable impurities" is used as a term that includes unavoidable impurities other than gas unavoidable impurities. In this specification, the amount of unavoidable metallic impurities may be a value measured by glow discharge mass spectrometry (GDMS). The amount of unavoidable impurities in a gas may be a value measured by an analyzer manufactured by LECO (e.g., CS600 for C). Furthermore, during measurement, the entire target may be analyzed, or a portion of the target may be sampled and analyzed. When a portion of the target is sampled and analyzed, samples may be sampled from multiple locations and an average value may be calculated. 1-2. organizational structure In one embodiment, the target of the present disclosure includes at least a Co phase and an intermetallic compound phase. The Co phase is also called a Co solid solution phase and is a phase containing predominantly Co. On the other hand, the intermetallic compound phase includes, but is not limited to, a CoZr phase, a Co 23 Zr6 phase, Co2Ta phase, Co2(Ta 0.5 Zr 0.5 In addition to the Co phase and the intermetallic compound phase, a Ta phase may also be present. The Co phase and the intermetallic compound phase can be visually distinguished in structural observation using an SEM. If necessary, elements contained in each phase can be detected using, for example, EPMA or EDX. In fact, concave and convex portions are observed in images obtained by structural observation (see, for example, Figure 3). In one embodiment, the Co phase of the target of the present disclosure has a fine size and is uniformly dispersed, preferably at a higher degree of uniform dispersion than that of the Co phase of a conventional target. In one embodiment, the average number Z of boundaries between adjacent phases is 15<Z when measured under the following conditions: ・Obtaining tissue images through SEM Draw five straight lines (L1 to L5) with a length of 40 μm, parallel to each other and spaced 10 μm apart. Count the number of boundaries (N1 to N5) between adjacent phases on each line (L1 to L5). ・Calculate the average number Z of each boundary number (N1 to N5). Here, as a result of EDX analysis using an EDX device, it was confirmed that the boundaries between adjacent phases, that is, the boundaries between the concave and convex portions, are often boundaries between the Co phase and the intermetallic compound phase. Therefore, the average number Z of the number of boundaries between adjacent phases (N1 to N5) serves as an index for evaluating the number of boundaries between the Co phase and the intermetallic compound phase. The tissue image is a tissue image with a 2000x field of view. An example of how to count the number of boundaries is shown in Figure 2. In Figure 2, three intermetallic compound phases M1 to M3 exist in the Co phase. Two lines L1 and L2 are drawn so that they are parallel and spaced 10 μm apart. In Figure 2, L1 has eight boundaries. In Figure 2, L2 has twelve boundaries. The range of the observation field of the SEM is not particularly limited, but it is preferable that the range be large enough to include the five straight lines with a length of 40 μm described above. Normally, magnetron sputtering involves placing a magnet behind the target (the non-sputtering surface) to allow magnetic flux to leak onto the target surface (the sputtering surface), converging the plasma in the leakage flux area, thereby enabling high-speed deposition. However, in the case of materials with high magnetic permeability, the leakage flux density is small, which results in insufficient plasma convergence, slowing deposition speed and ultimately reducing sputtering efficiency. However, when the value of Z is large, it indicates that the Co phase is fine in size and uniformly dispersed in the structure. This results in a low magnetic permeability of the target itself. If the magnetic permeability of the target is low, it is possible to avoid a decrease in the film formation rate during sputtering (especially magnetron sputtering). In one embodiment, the targets of the present disclosure have the textural characteristics described above, resulting in low magnetic permeability and, as a result, high sputtering efficiency. In a further embodiment, the average number α of intermetallic compound phases on the straight lines (L1 to L5) is 5 < α < 10. As for the number of intermetallic compound phases, as long as the convex portions in the obtained structure image are connected, they are counted as the same intermetallic compound phase, i.e., as one intermetallic compound phase. An example of a method for counting the number of intermetallic compound phases is shown in Figure 2. In Figure 2, three intermetallic compound phases M1 to M3 exist in the Co phase. Two lines L1 and L2 are drawn parallel to each other with a 10 μm gap between them. As mentioned above, the number of boundaries in L1 in Figure 2 is eight. However, L1 crosses the intermetallic compound phase M2 twice. Therefore, the number of intermetallic compound phases on L1 is three. On the other hand, the number of boundaries in L2 in Figure 2 is twelve. However, L2 crosses the intermetallic compound phase M1 five times. Therefore, the number of intermetallic compound phases on L2 is two. When the above-mentioned numerical range of Z is satisfied while the above-mentioned numerical range of α is satisfied, the intermetallic compound phase has a complex shape like a star or a starfish, rather than a simple shape such as a circle. A high degree of complexity of the shape means that the Co phase and the intermetallic compound phase are intricately intertwined, which means that unnecessary exfoliation of the intermetallic compound can be prevented. The measurement locations for the above-mentioned values ​​Z and α are not particularly limited, and may be, for example, the central portion of the target or the peripheral portion of the target. Preferably, the conditions for the above-mentioned values ​​Z and α are satisfied both at the central portion and at one peripheral portion. If the target is circular, the measurement location may be a portion corresponding to 1 / 2 of the radius (1 / 2R). If the target is circular, the conditions for the above-mentioned values ​​Z and α are typically satisfied at any of the central portion, the peripheral portion, and the 1 / 2R portion. Preferably, if the target is circular, the conditions for the above-mentioned values ​​Z and α are satisfied at any of the central portion, the peripheral portion, and the 1 / 2R portion. The number of measurement locations is also not particularly limited, and measurements may be taken at multiple locations and the average value may be used. Furthermore, the structural image for measuring the above-mentioned values ​​Z and α may be a structural image of a cross section parallel to the sputtering surface of the target (Pattern 1), or may be a structural image of a cross section perpendicular to the sputtering surface of the target (Pattern 2). The above-mentioned values ​​Z and / or α may be realized in at least one or more tissue images of Pattern 1 and Pattern 2. 1-3. Peak intensity when analyzed by X-ray diffraction In the target of one embodiment of the present disclosure, the following peaks are detected when analyzed by X-ray diffraction. Base peaks (I) from FCC (face-centered cubic)-Co phase and / or HCP (hexagonal close-packed)-Co phase ref ), CoZr2 phase and / or Co2(Ta 0.5 Zr 0.5 ) phase-derived first peak (I1), ・CoZr2 phase, Co 23 A second peak (I2) derived from at least one phase selected from the group consisting of a Zr6 phase and a Co2Ta phase; ・FCC-Co phase, HCP-Co phase, Co 23 A third peak (I3) derived from at least one phase selected from the group consisting of a Zr6 phase and a Co2Ta phase; and - The fourth peak (I4) derived from the CoTa phase, The intensity ratio of the first to fourth peaks to the intensity of the reference peak may be 0.8 or more. That is, all of the following relational expressions may be satisfied. (I) / (I ref ) >= 0.8 (preferably 1.0 or more) (I2) / (I ref ) >= 0.8 (preferably 0.9 or more) (I3) / (I ref ) >= 0.8 (preferably 1.0 or more) (I4) / (I ref ) >= 0.8 (preferably 1.0 or more) In a target according to a further embodiment of the present disclosure, the following peaks are detected when analyzed by X-ray diffraction: ・The fifth peak (I5) derived from the Ta phase The intensity ratio of the fifth peak to the intensity of the base peak may be 0.8 or more (i.e., (I5) / (I ref ) >= 0.8), and preferably 1.0 or more. The detection of such peaks indicates the presence of a certain amount of the desired intermetallic compound phase. The presence of the intermetallic compound phase can contribute to the refinement and dispersion of the Co phase. In detail, the detection of such peaks indicates the presence of the Co2Ta phase, and the presence of the CoZr2 phase, Co 23 Zr6 phase, and Co2 (Ta 0.5 Zr 0.5This suggests the possibility of the presence of a Ta phase, which is an alloy phase of various kinds, suggesting the presence of intermetallic compound phases. Since the intermetallic compound phase has a higher melting point than the Co phase, the intermetallic compound phase acts as a barrier in bonding between Co phases, suppressing the grain growth of pure Co and contributing to the refinement and dispersion of the Co phase. Furthermore, the detection of such a peak indicates the presence of a Ta phase. Since the Ta phase has a higher melting point than the Co phase, the Ta phase acts as a barrier in bonding between Co phases, suppressing the grain growth of pure Co and contributing to the refinement and dispersion of the Co phase. Here, the correspondence relationship between the above-mentioned reference peak and the first to fifth peaks and the 2θ angle is as follows: 2θ (°) Corresponding phase 75.67°±0.10° Base peaks derived from FCC-Co phase and / or HCP-Co phase 37.11°±0.10° CoZr2 phase, and / or Co2(Ta 0.5 Zr 0.5 ) phase-derived first peak 40.72°±0.10° CoZr2 phase, Co 23 A second peak derived from at least one phase selected from the group consisting of a Zr phase and a CoTa phase. 44.16°±0.10° FCC-Co phase, HCP-Co phase, Co 23 A third peak derived from at least one phase selected from the group consisting of Zr6 phase and Co2Ta phase 45.29°±0.10° Fourth peak due to CoTa phase 38.77°±0.10° Fifth peak derived from Ta phase Here, the intensity of each peak means the intensity measured under the following conditions. XRD evaluation device: Smartlab manufactured by Rigaku Corporation Analysis area of ​​sputtering target: Cut surface perpendicular to the sputtering surface and the center of the sputtering target X-ray source: Cu-Kα Tube voltage: 45 kV Tube current: 200mA Optical system: Concentration method Length limit slit: 10 mm Entrance slit: 1 / 2° Receiving slit 1: open state Receiving slit 2: 20 mm Goniometer: horizontal type Fluorescent X-ray reduction mode Scan speed: 4° / min Scan step: 0.01° Scan axis: 2θ / θ Scanning method: Continuous scan Measurement range: 2θ = 5° to 90° Background subtraction: The background is subtracted using a B-spline curve based on X-ray analysis software (Rigaku Corporation, SmartLab Studio II). The sample is prepared according to the following procedure. ・Polish the analysis area with #2000 waterproof abrasive paper. ・Furthermore, buffing is performed using a slurry in which alumina abrasive grains with a particle size of 0.3 μm are dispersed. ・Furthermore, etching is carried out using nitric acid diluted to a volume ratio of nitric acid to water of approximately 2:3 (the temperature of the etching solution is approximately 20°C ± 3°C, and the etching time is approximately 12 seconds ± 2 seconds). In a further embodiment, the following peaks are detected when a target of the present disclosure is analyzed by X-ray diffraction: - The sixth peak (I6) derived from the FCC-Co phase (2θ=51.40°±0.10°) - 7th peak (I7) derived from HCP-Co phase (2θ = 47.37° ± 0.10°) The ratio I6 / I7 between the two may be 0.3 or more and 0.7 or less, which indicates that the abundance ratio of the FCC-Co phase and the HCP-Co phase is not extremely biased toward one side. Furthermore, the ratio I7 / I3 between the seventh peak and the third peak may be 0.3 or more and 0.7 or less. 23This suggests at least one of the following possibilities: the abundance ratio of the HCP-Co phase to the intermetallic compound phases of Zr and CoTa is within a certain range; the abundance ratio of HCP-Co phases with different orientations is within a certain range; and the abundance ratio of the FCC-Co phase to the HCP-Co phase is within a certain range. 1-4. maximum permeability In one embodiment, the maximum magnetic permeability of the target of the present disclosure is 8 or less, preferably 6 or less. The measurement locations are not particularly limited, and for example, measurements may be taken at one location in the center of the target and four locations on the outer periphery of the target, and the maximum value may be used. For example, if the target has a disk-like (circular) shape, the four measurement locations may be four locations on the periphery (at 90-degree angles to each other). For example, if the target has a rectangular shape, the measurement locations may be four vertices. The maximum magnetic permeability can be measured by obtaining a magnetization curve using a B-H CURVE TRACER (model number BHU-6020) manufactured by Riken Denshi Co., Ltd. The size of the sample for measuring the maximum magnetic permeability is not particularly limited, but may be, for example, 5 mm W x 5 mm D x 15 mm H. For example, a size of 5 mm x 5 mm may be ensured in the direction along the sputtering surface of the target (hereinafter referred to as the "surface direction"), and a size of 15 mm may be ensured in the thickness direction of the target (pattern 1, i.e., the longest size in the thickness direction). In another example, a size of 15 mm x 5 mm may be ensured in the surface direction of the target, and a size of 5 mm may be ensured in the thickness direction of the target (pattern 2, i.e., the longest size in the surface direction). Then, in at least one or more samples of the above-mentioned patterns 1 and 2, any of the above-mentioned maximum magnetic permeabilities may be realized. 1-5. Other In one embodiment, the target of the present disclosure may be flat, preferably rectangular or circular. Furthermore, the size of the target of the present disclosure in one embodiment is not particularly limited. For example, if the target is disc-shaped, it may have a thickness of 3 to 15 mm and a diameter of 50 to 500 mm. For example, if the target is rectangular, it may have a width W of 50 to 500 mm, a depth D of 50 to 500 mm, and a height H of 3 to 15 mm. Furthermore, the relative density of the target of the present disclosure in one embodiment is not particularly limited, and may be, for example, 99.0% or more, and preferably 99.5% or more. The relative density can be determined by measuring the dimensions and weight of the target to calculate the dimensional density, and then calculating from the dimensional density and true density the following equation: relative density (%) = dimensional density / true density × 100. The true density is the specific gravity determined by the Archimedes method for a target of the same composition produced by a melting method. In general, targets can be manufactured by melting and casting (for example, by a process including machining such as melting and casting followed by rolling and forging), or by powder sintering (for example, by a process including preparing an alloy powder and then sintering it). In one embodiment, the target of the present disclosure is manufactured by powder sintering. 2. Target manufacturing method In one embodiment, the present disclosure relates to a method for producing a target comprised of Co, Ta, and Zr, said method comprising at least the following steps: A process of preparing powder consisting of Co, Ta, and Zr (i.e., powder of an alloy of Co, Ta, and Zr) by atomization. - A process of creating a sintered body by hot pressing powder Here, the step of preparing the powder includes adjusting the particle size distribution (volume basis) so as to satisfy the following conditions: ・D(10)v: 20-40μm ・D(50)v: 90-140μm ・D(90)v: 200-330μm The step of preparing the sintered body includes hot pressing under the following conditions. Temperature: 1100-1200℃, Holding time: 3 to 6 hours Pressure: 100 to 300 kgf / cm 2 Each step will be described in detail below. 2-1. Powder production process The powder is produced by atomization. The type of atomization is not limited, but gas atomization is preferred. For example, a powder can be produced by combining an ingot made of Co, an ingot made of Ta, and an ingot made of Zr and then atomizing the combined ingots. Alternatively, ingots made of Co, Ta, and Zr can be prepared in advance and then atomized to produce the powder. The particle size of the powder is adjusted to be −X μm (250<X<350). For example, a sieve with an opening size (or mesh size) of X μm may be used, and the powder that has passed through the sieve may be used. The particle size value X is a target value for operation. In other words, the particle size value X does not indicate the maximum particle size contained in the resulting powder mass. For example, when analyzing a particle mass that has passed through a sieve with a mesh of 300 μm, theoretically, particles with a particle size exceeding 300 μm cannot pass through. However, in reality, due to reasons such as shape, particles with a particle size exceeding 300 μm may pass through. Then, when the particle size of the powder after passing through is analyzed, the maximum particle size may exceed 300 μm. The D90 (volume basis) of the powder after particle size adjustment may be 200 to 330 μm. The D50 (volume basis) of the powder after particle size adjustment may be 90 to 140 μm. The D10 (volume basis) of the powder after particle size adjustment may be 20 to 40 μm. The above-mentioned D90, D50, and D10 (volume basis) values ​​are values ​​obtained by measuring particle size distribution by laser diffraction method. The powder after particle size adjustment is very fine, which results in a fine Co phase after sintering. Furthermore, in the process of producing a sintered body, which will be described later, processing must be performed at a relatively high temperature in order to achieve a sufficiently high density. However, as the temperature increases, the phase tends to become larger. By adjusting the particle size as described above, sufficient density can be achieved even at a relatively low temperature. Furthermore, since processing is performed at a low temperature, a fine Co phase can be maintained. The powder obtained by the atomization method preferably has high purity. High purity allows for the realization of a fine Co phase. For example, the purity of the powder may be 3N or higher, preferably 3N5 or higher. The purity of the powder described here is a purity excluding the inevitable gas impurities (i.e., C, H, N, and O) mentioned above. The content of the inevitable gas impurities contained in the powder obtained by the atomization method is not particularly limited, but may be, for example, as follows: C: 50 mass ppm or less (preferably, 40 mass ppm or less), O: 400 mass ppm or less (preferably, 180 mass ppm or less), N: 320 mass ppm or less (preferably, 200 mass ppm or less). The purity of the powder obtained by the atomization method can be measured by the same method as described in "1-1. Composition." 2-2. Process for creating sintered bodies After the powder is obtained, it is filled into a mold and sintered by hot pressing to produce a sintered body. The hot pressing conditions are as follows: Temperature: 1100-1200℃, Holding time: 3 to 6 hours Pressure: 100 to 300 kgf / cm 2 The step of preparing the sintered body may further include performing hot isostatic pressing (HIP). 2-3. Other After the sintered body is obtained, the sintered body may be further subjected to mechanical processing, such as grinding or cutting. As further specific examples of the above-described embodiment, examples will be described below. As with the above-described embodiment, the examples described below are not intended to limit the scope of the invention. Example 1 An ingot made of Co, an ingot made of Ta, and an ingot made of Zr were prepared, and the amounts of each ingot were adjusted so that the final composition would be as follows: ・Co 90-93at% Ta 3 to 5 at% Zr 3 to 5 at% The alloy powder was produced from these ingots by gas atomization. The powder that passed through a 300 μm mesh sieve was then collected. The powder was then filled into a mold and hot pressed under the following conditions: Temperature: 1100-1200℃ Holding time: 4-5 hours Pressure: 220 to 260 kgf / cm 2 After preparing a sintered body (having a disk shape), it was etched under the following conditions, and a 2000x field of view photograph of the structure (center, outer periphery, and the portion corresponding to 1 / 2R) was taken using an SEM (JSM-IT700HR, manufactured by JEOL Ltd.). The accelerating voltage, probe current, and contrast during SEM observation were set so that the concave and convex portions could be clearly observed and distinguished from each other. The obtained photographs were structural images obtained by observing secondary electron images. Furthermore, the obtained photographs show cross-sectional views of the sintered body in the thickness direction (in other words, the obtained photographs show photographs of the structure of a surface perpendicular to the in-plane direction of the sintered body). Five straight lines, each 40 μm long, were drawn on the photographs at 10 μm intervals (see Figures 3 to 5). The number of boundaries between the Co phase and the intermetallic compound phase on each of the five straight lines (i.e., the boundaries between the concave and convex portions) was counted. The average value Z of the measured values ​​was then calculated. (Etching conditions) ・Polish the analysis area with #2000 waterproof abrasive paper. ・Furthermore, buffing is performed using a slurry in which alumina abrasive grains with a particle size of 0.3 μm are dispersed. ・Furthermore, etching is carried out using nitric acid diluted to a volume ratio of nitric acid to water of approximately 2:3 (the temperature of the etching solution is approximately 20°C ± 3°C, and the etching time is approximately 12 seconds ± 2 seconds). In addition, the number of intermetallic compound phases on the five straight lines (L1 to L5) was counted. Then, the average number α of intermetallic compound phases on the five straight lines (L1 to L5) was calculated. As described above, as long as the convex portions in the photograph were connected, they were counted as the same intermetallic compound phase, i.e., as one intermetallic compound phase. The results are shown in Table 1. At every measurement point, the average number Z of boundaries exceeded 15, and the average number α of intermetallic compound phases was greater than 5 and less than 10. The relative density was measured by the above-mentioned method and was found to be 100.4%. Comparative Example 1 The microstructure photograph shown in FIG. 2 of Sample 1 (composition: Co-5Zr-5Nb) described in Patent Document 1 was analyzed. Specifically, lines were drawn in the same manner as in Example 1 above (see FIG. 1). Then, the average number Z of boundaries between the Co phase and the intermetallic compound phase was calculated. As a result, the value of Z was 11.2. In addition, the average number α of intermetallic compound phases on the straight lines (L1 to L5) was calculated. As a result, the value of α was 1. According to Patent Document 1, the maximum magnetic permeability of the material corresponding to Sample 1 was 16. Example 2 Atomization was performed under the same conditions as in Example 1, and the powder that passed through a 300 μm mesh sieve was collected. The impurities contained in the powder were analyzed using a LECO analyzer CS600 for C, a LECO analyzer TC600 for O and N, and glow discharge mass spectrometry (GDMS) (Thermo Fisher ELEMENT GD analyzer) for the other impurities. The results are shown in Tables 2 and 3. Example 3 Atomization was carried out under the same conditions as in Example 1, and the powder that passed through a 300 μm mesh sieve was collected. The particle size distribution was then analyzed using a laser diffraction method (equipment: Seishin Enterprise Co., Ltd., LMS-3000). As a result, the D90, D50, and D10 (volume basis) values ​​were as follows: D90: 281 μm D50: 116 μm D10: 31.3 μm Example 4 A sintered body was produced in the same manner as in Example 1. Then, the sintered body was subjected to X-ray diffraction analysis using the method described above. Then, the intensities of the portions corresponding to the base peak and the first to fifth peaks described above were measured. Then, the intensity ratios of the first to fifth peaks to the base peak were calculated. The results are shown in FIG. The intensity ratio of the first to fourth peaks to the reference peak was 0.8 or more. This indicates that an intermetallic compound phase is present and can contribute to the refinement of the Co phase. Furthermore, the intensity ratio of the fifth peak to the reference peak was 0.8 or more. This indicates that a Ta phase is present and can contribute to the refinement of the Co phase. The ratio of the sixth peak to the seventh peak was calculated separately. As a result, the value of I / I was 0.59. Furthermore, the value of I / I, which is the ratio of the seventh peak to the third peak, was 0.63. Next, samples were cut out from the center and outer periphery of the obtained sintered body to obtain samples (size: W 5 mm x D 5 mm x H 15 mm, specifically, 5 mm x 15 mm in the surface direction of the sintered body and 5 mm in the thickness direction of the sintered body). The samples were then analyzed under the following conditions using a B-H CURVE TRACER (model number BHU-6020) manufactured by Riken Denshi Co., Ltd. to measure the maximum magnetic permeability. As a result, the maximum magnetic permeability of the center sample was 4.2, and the maximum magnetic permeability of the outer periphery sample was 5.7. Note that the number of turns in the following conditions refers to the number of turns of the coil. Furthermore, the maximum magnetic permeability referred to here refers to the maximum magnetic permeability of a soft magnetic material. conditions Sample placement: The sample was placed between the two magnets and in contact with the two magnets, with the sample penetrating the inside of the coil. Magnet type: PBM-1 Measurement mode: Virgin Measurement cycle: 9 to 12 seconds / loop Demagnetization: The sample was demagnetized in advance using AC demagnetization to erase past history. Maximum applied magnetic field: 1kOe Number of primary turns: 454 Number of secondary turns: 10 Specific embodiments of the invention have been described above. The above embodiments are merely illustrative examples, and the present invention is not limited to these embodiments. For example, technical features disclosed in one of the above embodiments may be applied to other embodiments. Furthermore, unless otherwise specified, for a particular method, the order of some steps may be interchanged, and additional steps may be added between two specific steps. The scope of the present invention is defined by the claims.

Claims

1. A target made of Co, Ta, and Zr, having a maximum magnetic permeability of 8 or less.

2. A target according to claim 1, wherein the structure of the target includes a Co phase and an intermetallic compound phase, and the average number Z of boundaries between adjacent phases when measured under the following conditions is 15<Z: - Obtain a structure image through an SEM - Draw five straight lines (L1 to L5) with a length of 40 μm so that they are parallel to each other and spaced 10 μm apart - Count the number (N1 to N5) of boundaries between adjacent phases on each straight line (L1 to L5) - Calculate the average number Z of each number of boundaries (N1 to N5).

3. The target according to claim 2, wherein the average number α of the intermetallic compound phases on the straight lines (L1 to L5) is 5<α<10.

4. A target according to any one of claims 1 to 3, wherein the structure of the target contains a Co phase and an intermetallic compound phase, and when analyzed by X-ray diffraction, the following peaks are present: - Reference peaks derived from an FCC-Co phase and / or an HCP-Co phase, - CoZr2 phase and / or Co2(Ta 0.5 Zr 0.5 ) phase, the first peak due to CoZr2 phase, Co 23 A second peak derived from at least one phase selected from the group consisting of a Zr6 phase and a Co2Ta phase; a FCC-Co phase, a HCP-Co phase, a Co 23 a third peak derived from at least one phase selected from the group consisting of a Zr6 phase and a Co2Ta phase, and a fourth peak derived from a Co2Ta phase. A target in which the intensity ratios of the first peak, the second peak, the third peak, and the fourth peak to the reference peak are 0.8 or more.

5. The target according to claim 4, wherein, when analyzed by X-ray diffraction, a fifth peak derived from the Ta phase is present, and the intensity ratio of the fifth peak to the reference peak is 0.8 or more.

6. A method for manufacturing a target made of Co, Ta, and Zr, the method comprising: a step of preparing a powder made of Co, Ta, and Zr by an atomization method; and a step of preparing a sintered body from the powder by a hot pressing method, wherein the step of preparing the powder comprises adjusting the particle size distribution to satisfy the following conditions: D(10)v: 20 to 40 μm D(50)v: 90 to 140 μm D(90)v: 200 to 330 μm, and the step of preparing the sintered body comprises hot pressing under the following conditions: Temperature: 1100 to 1200°C, Holding time: 3 to 6 hours, Pressure: 100 to 300 kgf / cm. 2 method.

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