Sputtering target and method for manufacturing sputtering target

Abstract

The invention relates to a sputtering target and a method for manufacturing the sputtering target. Provided is a method for producing a sputtering target, comprising a step for preparing, as metal powders, 10-85 mol% of Co, 0-47 mol% of Pt, and 0-47 mol% of Cr, adding at least 0.3-4.0 mol% of B6O as an oxide powder to the metal powders, mixing the metal powders, sintering the obtained powder at 900-1200 DEG C, and sintering the sintered powder at 900-1200 DEG C to obtain the sputtering target. A sputtering target having a diffraction peak of B6O (110) in the range of 2 [theta] = 30-35 degrees and a diffraction peak of B6O (104) in the range of 2 [theta] = 35-40 degrees in an XRD diffraction pattern in which Cu is used as a radiation source, and having a B elution amount of 500 [mu] g / L / cm2 or less, is obtained.

Description

[0001] This application is a divisional application of the invention patent application with application number 201980095022.1, application date September 20, 2019 and invention name “Sputtering target and method for manufacturing sputtering target”. Technical Field

[0002] The present invention relates to a sputtering target and a method for manufacturing the sputtering target. Background Art

[0003] In the field of magnetic recording represented by hard disk drives, materials based on Co, a ferromagnetic metal, are used as materials for magnetic thin films that bear recording. Sputtering targets for magnetic recording mostly use composite materials composed of ferromagnetic alloys and non-magnetic materials, and sputtering targets to which boron oxide is added as a non-magnetic material are known.

[0004] For example, the following example is described in Japanese Patent Gazette No. 5878242 (Patent Document 1): A sputtering target for forming a magnetic recording film, comprising a sintered body comprising at least cobalt as a metal, boron and / or one or more metals or alloys selected from the platinum group elements and oxides, wherein at least one of Cr(BO3), Co2B2O5, and Co3B2O6 is present in the oxide-containing phase. By using a composite oxide such as Cr(BO3) for sintering, a boron-containing sputtering target with higher quality and better production efficiency can be obtained.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5878242 Summary of the invention

[0008] Problems to be solved by the invention

[0009] A sputtering target to which boron oxide is added as a non-magnetic material has the following problem: after sintering, the particles of the boron oxide become larger, and if the sintering temperature is lowered to suppress grain growth, the density cannot be increased, resulting in a large amount of particles being generated.

[0010] For example, since B2O3, one of the non-magnetic materials, has a low melting point, if B2O3 raw material is used directly, when sintering is performed below the melting point, the density may not be sufficiently increased, and the risk of large-scale particle generation increases. However, when sintering is performed above the melting point, not only does B2O3 melt during sintering, causing uneven composition, but also coarse particles are formed and large-scale particles are generated, making it difficult to stably obtain a high-quality sputtering target.

[0011] On the other hand, for example, in Patent Document 1, by using composite oxides with high melting points such as Cr(BO3), Co2B2O5, and Co3B2O6, the sintering temperature is increased to increase the density, thereby suppressing the generation of particles during the sputtering process. However, if Co2B2O5 or Co3B2O6 is used in the production of Co-Pt-B2O3-SiO2, for example, metal B is used instead. Depending on the sintering conditions, metal B reacts with SiO2 to produce large particles. If the sintered body obtained in this way is used as a target, a large amount of particles may be generated. The reaction of metal B with oxides can occur even with oxides other than SiO2.

[0012] In view of the above problems, the present disclosure provides a sputtering target capable of reducing the generation of particles and a method for manufacturing the same.

[0013] Solutions for solving problems

[0014] In one embodiment of the present invention, a sputtering target is a sputtering target characterized in that it contains 10 mol% to 85 mol% Co, 0 mol% to 47 mol% Pt, and 0 mol% to 47 mol% Cr as metal components, and at least B6O as an oxide component.

[0015] Effects of the Invention

[0016] According to the present disclosure, a sputtering target capable of reducing the generation of particles and a method for manufacturing the same can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Graph showing the particle evaluation results of Example 1 and Comparative Example 1.

[0018] Figure 2 This is a graph showing the XRD measurement results of Example 4. DETAILED DESCRIPTION

[0019] The sputtering target according to the embodiment of the present invention includes a metal layer composed of a metal component constituting a target base (matrix) portion and an oxide layer composed of an oxide component.

[0020] (Metallic Phase)

[0021] As the metal components constituting the target substrate (matrix) part, the composition of Pt and Co is mainly determined by the magnetic properties required by the magnetic recording layer. The lower limit of Pt in the target substrate can be set to 5mol%, and the lower limit of Co is set to 55mol%. If it is lower than their lower limits, the magnetization characteristics required for the magnetic recording layer of the perpendicular magnetic recording method cannot be obtained. Regarding Pt in the target substrate, the preferred composition range is 10mol% or more, and more preferably 15mol% or more. Regarding Co, the preferred composition range is 60mol% or more.

[0022] On the other hand, the upper limit of Pt in the target substrate is 45mol%, and the upper limit of Co is 95mol%. Even if these upper limits are exceeded, the magnetization characteristics required for the magnetic recording layer of the perpendicular magnetic recording method cannot be obtained. Regarding Pt, the preferred composition range is 40mol% or less, and more preferably 30mol% or less. Regarding Co, the preferred composition range is 85mol% or less, and more preferably 75mol% or less.

[0023] Furthermore, as a metal component constituting the matrix, Cr may be arbitrarily contained according to the magnetic properties of the magnetic recording layer. The Cr content in the target matrix is ​​preferably 40 mol% or less, more preferably 20 mol% or less of the matrix metal component, and even more preferably 10 mol% or less.

[0024] (Oxide Phase)

[0025] According to the magnetic properties of the magnetic recording layer, one or more oxides selected from the group consisting of Cr, Ta, Ti, Si, Zr, Al, Nb, B and Co may be included as the oxide component. The volume ratio of the total amount of the oxides of the oxide component to the entire sputtering target is preferably 1 mol% to 20 mol%, more preferably 3 mol% to 15 mol%, and further preferably 5 mol% to 10 mol%.

[0026] As additional elements, additional element components selected from the group consisting of B, N, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Si and Al can be added in a total of 35 mol% or less, preferably adding the additional elements in a total of 20 mol% or less, and further preferably adding the additional elements in a total of 10 mol% or less.

[0027] (Overall composition of sputtering target)

[0028] The sputtering target according to the embodiment of the present invention contains 10 mol % to 85 mol % Co, 0 mol % to 47 mol % Pt, and 0 mol % to 47 mol % Cr as metal components, and contains at least B6O as an oxide component.

[0029] It preferably contains 20 to 60 mol% of Co, more preferably 30 to 50 mol% of Co. It preferably contains 10 to 40 mol% of Pt, more preferably 20 to 30 mol% of Pt. It preferably contains 5 to 30 mol% of Cr, more preferably 10 to 20 mol% of Cr.

[0030] The sputtering target may contain 0.1 mol% to 10 mol% B6O, and more preferably 0.3 mol% to 4.0 mol% B6O.

[0031] The presence of B6O can also be confirmed by XRD diffraction of a sintered sample. Specifically, the XRD diffraction pattern with Cu as the radiation source has a diffraction peak of B6O (110) in the range of 2θ = 30 to 35°, and a diffraction peak of B6O (104) in the range of 2θ = 35 to 40°.

[0032] The half-width of the diffraction peak of B6O(110) at 2θ=30-35° is 0.5 degree or more, further 0.6 degree or more, and typically 0.5-0.8 degree. The half-width of the diffraction peak of B6O(104) at 2θ=35-40° is 0.5 degree or more, further 0.6 degree or more, and typically 0.6-1.0 degree.

[0033] The target of the embodiment of the present invention includes a B dissolution amount of 1000 μg / L / cm 2 The B elution amount refers to the B concentration in the case where the B concentration in the leached water obtained by immersing the target in a volume of water at room temperature that is not saturated with B2O3 is measured using an inductively coupled plasma device (ICP). The B elution amount is preferably 700 μg / L / cm 2 Below, more preferably 500 μg / L / cm 2 Below, more preferably 300 μg / L / cm 2 It should be noted that when the amount of B elution is small, there is an effect of suppressing the deterioration of the target surface due to the dissolution of boron oxide into water when water or moisture in the atmosphere adheres to the target surface.

[0034] The sputtering target of the embodiment of the present invention can be produced by a powder sintering method. That is, the sputtering target of the embodiment of the present invention includes sintering the following powder: the powder is prepared as metal powders of 10 mol% to 85 mol% Co, 0 mol% to 47 mol% Pt, 0 mol% to 47 mol% Cr, and B6O is added to the metal powders as oxide powders to mix. Preferably, B6O is added in an amount of 0.1 mol% to 10 mol%, and more preferably, B6O is added in an amount of 0.3 mol% to 4.0 mol%.

[0035] Co powder, Pt powder, Cr powder, and B6O powder preferably have an average particle size of 3 μm or less. The average particle size of these powders refers to the median particle size measured by a laser diffraction scattering method.

[0036] The metal powder and the oxide powder can be mixed by pulverizing using a known method such as sieve mixing or mortar mixing. The mixed powder thus obtained is molded and sintered by hot pressing in a vacuum environment or an inert gas atmosphere.

[0037] In the sintering process, the sintering temperature is heated to 700° C. to 1200° C. or lower in order to increase the relative density. If the sintering temperature is too low, the density may not be sufficiently increased.

[0038] According to the sputtering target and the manufacturing method thereof of the embodiment of the present invention, in the sputtering target to which boron oxide is added as a non-magnetic material, by preparing a sputtering target containing B6O, the generation of particles can be reduced compared with the case where materials such as B2O3 that melts at a low temperature are used.

[0039] The present disclosure is described through the above-mentioned embodiments, but the discussion and drawings constituting a part of the disclosure should not be understood as limiting the present invention. That is, the present invention is not limited to each embodiment, and the constituent elements can be deformed and concretized within the scope of its purport. In addition, various inventions can be formed by appropriately combining multiple constituent elements disclosed in each embodiment. For example, some constituent elements can also be deleted from all constituent elements shown in the embodiment. Moreover, the constituent elements of different embodiments can also be appropriately combined.

[0040] Example

[0041] Examples of the present invention and comparative examples are shown below, but these examples are provided for better understanding of the present invention and its advantages and are not intended to limit the present invention.

[0042] (Example 1, Comparative Example 1)

[0043] The powders of each material were weighed in such a way that the composition became Co-7.7Pt-7.7B-3.8Ti-19.2Oat%, and the mixed powder obtained by mixing the powders of each material was hot pressed for 5 hours at the sintering temperature and pressure of 20MPa in a vacuum environment shown in Table 1 to produce the sintered bodies of Example 1 and Comparative Example 1. In Example 1, B6O powder with an average particle size of 3μm was used for production, and in Comparative Example 1, B2O3 powder with an average particle size of 3μm was used for production. The sintered bodies of Example 1 and Comparative Example 1 were processed into a target shape, and the number of particles generated during sputtering was evaluated. In the evaluation, a magnetron sputtering device (C-3010 sputtering system manufactured by Canon Anelva) was used. The sputtering conditions were set to an input power of 0.5kW and an Ar gas pressure of 1.7Pa, and the film was formed on a silicon substrate for 40 seconds.

[0044] The number of particles (particle size 0.09 to 3 μm) attached to the substrate was measured using a particle counter (manufactured by KLA-Tencor, device name: Candela CS920). The results are shown in Figure 1 The number of particles in Comparative Example 1 is about 500, whereas the number of particles in Example 1 is about 100. It can be seen that the target of Example 1 using B6O powder is effective in reducing particles compared with the target of Comparative Example 1 and has good sputtering characteristics.

[0045] (Example 2 to Example 10, Comparative Example 2 to Comparative Example 9)

[0046] The raw material powders shown in Table 1 were weighed to have the composition shown in Table 1, and the mixed powders obtained by mixing the raw material powders were hot pressed at the sintering temperature in Table 1, at a pressure of 20 MPa, and in a vacuum environment for 5 hours to produce sintered bodies of Examples 2 to 10 and Comparative Examples 2 to 9. In Examples 2 to 10, B6O powders with an average particle size of 3 μm were used, and in Comparative Examples 2 to 9, B2O3 powders with an average particle size of 3 μm were used.

[0047] The presence or absence of an XRD diffraction peak of B6O was confirmed for the sintered bodies of Examples 1 to 10 and Comparative Examples 1 to 9. The XRD measurement conditions were as follows.

[0048] Analytical apparatus: X-ray diffractometer (in the examples, a fully automatic horizontal multi-purpose X-ray diffractometer SmartLab manufactured by Rigaku Corporation was used).

[0049] Bulb: Cu (determined by CuKα).

[0050] Tube voltage: 40kV.

[0051] Tube current: 30mA.

[0052] Optical system: Concentrated diffraction optical system.

[0053] Scan mode: 2θ / θ.

[0054] Scanning range (2θ): 30°~55°.

[0055] Measurement step (2θ): 0.02°.

[0056] Scanning speed (2θ): 0.5° per minute.

[0057] Accessories: Standard accessories.

[0058] Filter: CuKβ filter.

[0059] Counter monochrome: No.

[0060] Counter:D / teX Ultra.

[0061] Divergence slit: 2 / 3deg.

[0062] Divergent longitudinal slit: 10.0mm.

[0063] Scattering slit: 10.0mm.

[0064] Light receiving slit: 10.0mm.

[0065] Attenuator: On.

[0066] It was confirmed whether there was a diffraction peak of B6O(110) in the range of 2θ=30-35° and a diffraction peak of B6O(104) in the range of 2θ=35-40° in the XRD diffraction spectrum. As a result, in Examples 1 to 10, diffraction peaks of B6O(110) and B6O(104) were shown even in the sintered bodies. The results are shown in Table 1. It should be noted that the composition and the ratio of raw materials used in Table 1 are the results obtained by rounding off the second decimal place.

[0067] [Table 1]

[0068]

[0069] The graph showing the XRD diffraction peaks of Example 4 is shown in FIG. Figure 2 .like Figure 2 As shown, the sintered body according to Example 4 has a diffraction peak of B6O(110) in the range of 2θ=30~35° in the XRD diffraction spectrum, and a diffraction peak of B6O(104) in the range of 2θ=35~40°, and the half-widths are in the ranges of 0.5~0.8deg and 0.6~1.0deg, respectively.

[0070] The amount of B dissolved (the amount of boron dissolved in water) was measured for the sintered bodies of Examples 1 to 10 and Comparative Examples 1 to 9. The amount of B dissolved was measured as follows. First, a sample of 3 mm × 3 mm × 20 mm (the surface was dry processed) was made from the sintered body. The surface of the sample was made into a dry-ground state and was not in contact with solvents such as water or ethanol. Next, the sample was immersed in 50 to 100 cc of water at room temperature. Since the solubility of B2O3 is 0.028 g / cc, B2O3 will not be saturated as long as the water is more than 50 cc, but if the water exceeds 100 cc, the B concentration becomes dilute and becomes difficult to analyze. For the water in which the sample is immersed, the amount of boron dissolved is measured using ICP (SPS3500DD manufactured by Hitachi High-Technologies Corporation), and the value obtained by dividing the weight of B in the dissolved water obtained by the measurement by the volume of the dissolved water and the surface area of ​​the sample is taken as the amount of B dissolved. In Examples 1 to 10 where the diffraction peak of B6O was observed by XRD, the amount of B dissolved was 1000 μg / L / cm 2 In Comparative Examples 1 to 9 in which no diffraction peak of B6O was observed by XRD, the amount of B eluted was 1000 μg / L / cm 2 above.

Claims

1. A method for manufacturing a sputtering target, comprising the following steps: Prepare metal powder containing 10 mol % to 85 mol % of Co, 0 mol % to 47 mol % of Pt, and 0 mol % to 47 mol % of Cr, At least 0.3 mol % to 4.0 mol % of B6O as oxide powder is added to the metal powder and mixed, and the obtained powder is sintered at 900° C. to 1200° C., A sputtering target was obtained, wherein the sputtering target had a diffraction peak of B6O(110) in the range of 2θ=30-35° and a diffraction peak of B6O(104) in the range of 2θ=35-40° in an XRD diffraction pattern with Cu as a radiation source, and a B dissolution amount of 500 μg / L / cm 2 the following.

2. The method for producing a sputtering target according to claim 1, wherein: The metal powder includes Co powder, Pt powder, Cr powder and B6O powder having an average particle size of 3 μm or less.

3. The method for producing a sputtering target according to claim 1, wherein: This includes adding 1.7 mol % or more and 4.0 mol % or less of B6O.

4. The method for producing a sputtering target according to claim 1, wherein: The diffraction peak of the B6O(110) and the diffraction peak of the B6O(104) are greater than 0.5 degrees.

5. The method for producing a sputtering target according to claim 1, wherein: The invention comprises obtaining the sputtering target, wherein the sputtering target contains an oxide selected from the group consisting of Cr, Ta, Ti, Si, Zr, Al, Nb, B and Co as the oxide component, and the volume ratio of the total amount of the oxide to the entire sputtering target is greater than 1 mol% and less than 20 mol%.

6. The method for producing a sputtering target according to claim 1, wherein: The present invention comprises obtaining the sputtering target, wherein the sputtering target contains 35 mol% or less of additive element components selected from the group consisting of B, N, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Si and Al in total.

7. A sputtering target, characterized in that: The sputtering target is manufactured by the method for manufacturing a sputtering target according to any one of claims 1 to 6, wherein the sputtering target contains 10 mol% to 85 mol% Co, 0 mol% to 47 mol% Pt, and 0 mol% to 47 mol% Cr as metal components, and contains at least 0.3 mol% to 4.0 mol% B6O as an oxide component, and the B dissolution amount is 500 μg / L / cm 2 Hereinafter, in the XRD diffraction pattern using Cu as the radiation source, there is a diffraction peak of B6O(110) in the range of 2θ=30 to 35°, and there is a diffraction peak of B6O(104) in the range of 2θ=35 to 40°.

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