Co-Cr-Pt-oxide sputtering target

Abstract

A Co-Cr-Pt-oxide sputtering target which contains 50 at% or more of Co, more than 0 at% and 20 at% or less of Cr, and more than 0 at% and 25 at% or less of Pt, with the remainder comprising one or more oxides and unavoidable impurities, and which is characterized by containing (A) a composite phase in which Co, Pt, and oxides are dispersed with each other, and (B) a metal Cr phase, 10 or more metal Cr phases having an equivalent circle diameter of more than 10 [mu] m and 100 [mu] m or less are included in a 1 mm * 1 mm observation field of view using an SEM having an observation magnification of 50 times.

Description

Technical Field

[0001] The present invention relates to a sputtering target suitable for forming a magnetic thin film, especially a granular film, used in a magnetic recording layer of a magnetic recording medium, and more particularly to a Co-Cr-Pt-oxide sputtering target capable of improving discharge stability during sputtering. Background Art

[0002] Various compositions are used in sputtering targets containing Co-Cr-Pt-oxide. For example, WO2013 / 136962A1 (Patent Document 1) states that Co-Cr-Pt-oxide is mainly composed of an oxide containing one or more components selected from B, Si, Cr, Ti, Ta, W, Al, Mg, Mn, Ca, Zr, and Y as an oxide, and contains one or more elements selected from B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Ag, Au, Cu, and C as an additive element.

[0003] Sputtering targets containing these oxides as insulators have the problem of causing abnormal discharge and generating particles. In order to solve this problem, the probability of abnormal discharge is generally suppressed by making the oxides fine and uniform in the structure. For example, Patent Document 1 also states that in a Co-Cr-Pt-oxide sputtering target, abnormal discharge can be suppressed by miniaturizing the average particle size of the oxide to 400 nm or less.

[0004] WO2013 / 125469A1 (Patent Document 2) states that in addition to making the oxide particles smaller, the oxide particles are also made to exist in a true spherical shape or a shape close to a true spherical shape. As a result, there is no difference in the distribution of the areas where the oxide exists and the areas where the oxide does not exist on a certain area of ​​the target surface, and segregation is reduced, which can effectively suppress abnormal discharge and particle generation.

[0005] On the other hand, most of the sputtering targets of these compositions have strong magnetism, and the leakage flux density (PTF) is small, and high voltage needs to be applied during sputtering. If the voltage during sputtering is high, the voltage becomes unstable and arcs are easily generated. In view of this problem, it is a general solution to reduce the necessary voltage during sputtering by increasing PTF. Although several methods for improving PTF are disclosed, for example, in Japanese Patent Publication No. 2013-108110 (Patent Document 3), it is described that a magnetic phase consisting of a Co-Cr alloy phase containing more than 85 atomic % of Co, a non-magnetic phase consisting of a Co-Cr alloy phase containing more than 0 atomic % and less than 75 atomic % of Co or a Co-Cr-Pt alloy phase containing more than 0 atomic % and less than 73 atomic % of Co, and a non-magnetic phase consisting of a Co-Pt alloy phase containing less than 12 atomic % of Co are included in a sputtering target in which a non-magnetic phase and an oxide phase are dispersed with each other and a magnetic phase and a non-magnetic phase are included, and the magnetism of each phase is controlled by the content ratio of Co to improve PTF.

[0006] WO2011 / 089760A1 (Patent Document 4) describes that leakage flux is improved by having a metal matrix composed of an inorganic material and a spherical phase (particularly, having a diameter of 30 to 150 μm) containing 90 wt % or more of Co.

[0007] Japanese Patent Publication No. 2016-176087 (Patent Document 5) states that in a Co-Cr-Pt-oxide-based ferromagnetic sputtering target, the leakage flux is improved by having a metal matrix containing an inorganic material and a phase composed of Pt with a shortest diameter of 10 to 150 μm. In addition, WO2012 / 081669A1 (Patent Document 6) states that in a Co-Cr-Pt-oxide-based ferromagnetic sputtering target, the leakage flux density is improved and the voltage during sputtering is stabilized by having a Co-Pt alloy phase (B) with a diameter of 10 to 150 μm and a Co alloy phase (C) with a diameter of 30 to 150 μm and containing more than 90 mol % of Co in a metal matrix (A) in which oxides are dispersed.

[0008] WO2010 / 110033A1 (Patent Document 7) states that: by providing a Co-Cr-Pt-oxide system with a phase (A) in which non-magnetic particles are uniformly and finely dispersed in the alloy, and a spherical alloy phase (B) with a composition in which the Cr content in the center is 25 mol % or more and the Cr content decreases from the center toward the periphery as compared with the center, the volume occupied by the alloy phase (B) in the target is set to be greater than 4% and less than 40%, thereby increasing the leakage magnetic flux.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: WO2013 / 136962A1

[0012] Patent Document 2: WO2013 / 125469A1

[0013] Patent Document 3: Japanese Patent Application Publication No. 2013-108110

[0014] Patent Document 4: WO2011 / 089760A1

[0015] Patent Document 5: Japanese Patent Application Publication No. 2016-176087

[0016] Patent Document 6: WO2012 / 081669A1

[0017] Patent Document 7: WO2010 / 110033A1 Summary of the invention

[0018] Problems to be solved by the invention

[0019] Various compositions have been proposed for Co—Cr—Pt-oxide-based sputtering targets.

[0020] WO2013 / 125469A1 (Patent Document 2) discloses suppressing abnormal discharge and particles by making oxide particles into a specified shape, and Japanese Patent Publication No. 2013-108110 (Patent Document 3) discloses controlling the magnetism of each phase and improving the PTF by making the Co content ratio of the magnetic phase and the non-magnetic phase different, but it is difficult to say that the voltage stability is sufficient.

[0021] WO2011 / 089760A1 (Patent Document 4) discloses that by allowing a spherical phase containing 90 wt % or more of Co to exist, the leakage flux density is increased and the voltage during sputtering becomes stable; Japanese Patent Publication No. 2016-176087 (Patent Document 5) discloses that by allowing a phase composed of Pt to exist, the leakage flux density is increased and the voltage during sputtering becomes stable; WO2012 / 081669A1 (Patent Document 6) discloses that by allowing Co-Pt The alloy phase (B) and the Co alloy phase (C) containing more than 90 mol% of Co exist in a specified size and shape, so that the leakage flux density is increased and the voltage during sputtering becomes stable; in addition, WO2010 / 110033A1 (Patent Document 7) discloses that the leakage flux density is increased and the voltage during sputtering is stabilized by the presence of a spherical alloy phase (B) with a composition in which the Cr content in the center is more than 25 mol% and the Cr content from the center to the periphery becomes lower than that in the center. However, there is the following problem: the composition and leakage flux density of the sputtering target used in the manufacture of the magnetic recording medium are limited to the composition and leakage flux density that are suitable for the mass production system and can not be easily changed.

[0022] An object of the present invention is to provide a sputtering target and a method for producing the same, which can stabilize the voltage during sputtering without relying on a method of changing the composition and the leakage magnetic flux density.

[0023] Methods used to solve problems

[0024] The present inventors have conducted intensive research to solve the above problems and found that by using a sputtering target having a cross section containing 10 particles / mm 2 The sputtering target having a metal Cr phase structure with an equivalent circle diameter greater than 10 μm and less than 100 μm can reduce the voltage during sputtering and stabilize the discharge while maintaining the composition and leakage flux density, thereby completing the present invention.

[0025] According to the present invention, a Co—Cr—Pt-oxide-based sputtering target having the following characteristics can be provided.

[0026] [1] A sputtering target, which is a Co-Cr-Pt-oxide sputtering target containing 50 atomic % or more of Co, more than 0 atomic % and less than 20 atomic % of Cr, and more than 0 atomic % and less than 25 atomic % of Pt, with the balance consisting of one or more oxides and unavoidable impurities, characterized in that it contains (A) a composite phase in which Co, Pt and oxides are dispersed in each other and (B) a metal Cr phase, and contains at least 10 metal Cr phases with an equivalent circle diameter of more than 10 μm and less than 100 μm within a 1 mm×1 mm observation field of view using a scanning electron microscope with an observation magnification of 50 times.

[0027] [2] A sputtering target, which is a Co-Cr-Pt-oxide sputtering target containing more than 50 atomic % of Co, more than 0 atomic % and less than 20 atomic % of Cr, and more than 0 atomic % and less than 25 atomic % of Pt, with the balance consisting of one or more oxides and unavoidable impurities, characterized in that it contains (A) a composite phase in which Co, Pt and oxides are dispersed in each other, (B) a metal Cr phase, and (C) an alloy phase containing Co or Pt, and contains more than 10 metal Cr phases with an equivalent circle diameter greater than 10 μm and less than 100 μm within a 1 mm×1 mm observation field of view using a SEM with an observation magnification of 50 times.

[0028] [3] The sputtering target according to [1] or [2] above is characterized in that the above-mentioned composite phase also contains one or more selected from B, Al, Si, Ti, V, Mn, Fe, Ni, Cu, Zn, Ge, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Ir and Au.

[0029] [4] The sputtering target according to any one of [1] to [3], wherein the oxide is contained in an amount of 20% by volume or more and 50% by volume or less in the sputtering target.

[0030] [5] A sputtering target according to any one of [1] to [4] above, characterized in that the oxide is an oxide of an element selected from one or any combination of two or more selected from B, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Ta, W, La, Ce, Nd, Sm, and Gd.

[0031] [6] The sputtering target according to any one of [1] to [5] above, wherein the oxide contains at least boron oxide.

[0032] [7] A method for manufacturing a sputtering target, which is the method for manufacturing a sputtering target described in [1] or [2] above, characterized in that powders of raw materials including Cr metal powder and oxide powder having an average particle size of not less than 150 μm and not more than 1000 μm are mixed and stirred to prepare a mixed powder for the target, and the mixed powder for the target is sintered.

[0033] [8] A method for manufacturing a sputtering target, which is the method for manufacturing a sputtering target described in [1] or [2] above, characterized in that Cr metal powder having an average particle size of not less than 10 μm and not more than 150 μm is added to a mixed powder obtained by stirring and mixing other raw material powders and oxides.

[0034] Effects of the Invention

[0035] The Co-Cr-Pt-oxide sputtering target of the present invention can reduce the voltage during sputtering, stabilize the discharge and inhibit the occurrence of arcs even if it has the same composition and leakage magnetic flux density because it has a sputtering surface containing a metal Cr phase with an equivalent circle diameter greater than 10 μm and an area less than 100 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is an explanatory diagram showing the definition of the equivalent circle diameter.

[0037] Figure 2 This is a structural photograph of the cross section of the sputtering target obtained in Example 1, in which each phase was identified by composition mapping analysis using EDX.

[0038] Figure 3 This is an image obtained by enlarging a field of view of 1 mm×1 mm from the SEM image of the sputtering target cross section obtained in Example 1 at a magnification of 50 times and performing binarization processing.

[0039] Figure 4 This is a structural photograph of the cross section of the sputtering target obtained in Comparative Example 1, in which each phase was identified by composition mapping analysis using EDX.

[0040] Figure 5 This is a structural photograph of the cross section of the sputtering target obtained in Comparative Example 2, in which each phase was identified by composition mapping analysis using EDX.

[0041] Figure 6 This is a structural photograph of the cross section of the sputtering target obtained in Example 5, in which each phase was identified by composition mapping analysis using EDX. DETAILED DESCRIPTION

[0042] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

[0043] The Co-Cr-Pt-oxide sputtering target of the present invention is characterized in that it contains 10 or more metal Cr phases having an equivalent circle diameter greater than 10 μm and less than 100 μm within a 1 mm×1 mm observation field of view using a SEM with an observation magnification of 50 times. The equivalent circle diameter refers to, for example Figure 1 As shown, it is assumed that the diameter of a circle is equal to the area of ​​the metal Cr phase of an unspecified shape. As shown in the examples described later, by the presence of a metal Cr phase with a large area, the voltage during sputtering is reduced and the discharge becomes stable. In the 1mm×1mm observation field of view using a SEM with an observation magnification of 50 times, the metal Cr phase is dark or black, and the composite phase is light, that is, gray to white. The SEM observation image is binarized and image processing is performed, thereby extracting the dark or black metal Cr phase and finding its area, and calculating the equivalent circle diameter.

[0044] The metallic Cr phase can be identified by composition mapping analysis using EDX of the cross section of the sputtering target. When the weight ratio of the target composition is quantitatively analyzed, the ideal region is 100% by weight of Cr, but considering the inevitable analysis error, the region consisting of 95% by weight or more, preferably 97% by weight or more of Cr and inevitable impurities is regarded as the "metallic Cr phase".

[0045] [First embodiment]

[0046] The Co-Cr-Pt-oxide sputtering target of the first embodiment is a Co-Cr-Pt-oxide sputtering target containing more than 50 atomic % of Co, more than 0 atomic % and less than 20 atomic % of Cr, and more than 0 atomic % and less than 25 atomic % of Pt, and the balance is composed of one or more oxides and unavoidable impurities, characterized in that it contains (A) a composite phase in which Co, Pt and oxides are dispersed with each other and (B) a metallic Cr phase, and contains more than 10 metallic Cr phases with an equivalent circle diameter greater than 10 μm and less than 100 μm within an observation field of 1 mm×1 mm using a SEM with an observation magnification of 50 times.

[0047] (B) The equivalent circular diameter of the metal Cr phase is greater than 10 μm and less than 100 μm, preferably the equivalent circular diameter is greater than 20 μm, more preferably greater than 25 μm, preferably less than 70 μm, more preferably less than 60 μm. If the equivalent circular diameter of the metal Cr phase is greater than 100 μm, the target surface during sputtering will be significantly uneven due to the difference in sputtering rate, and problems such as particles and arcs are likely to occur. When the equivalent circular diameter of the metal Cr phase is less than 10 μm, it is difficult to obtain the voltage reduction effect during sputtering. In addition, diffusion reactions are likely to occur between the metal Cr phase and other phases at the grain boundaries, and Cr alloy phases or Cr oxide phases are likely to be generated.

[0048] There are more than 10 metal Cr phases with an area within the above range in the observation field of 1mm×1mm using a SEM with an observation magnification of 50 times, preferably more than 15, more preferably more than 20, preferably less than 300, and more preferably less than 100. If the metal Cr phases are less than 10, the effect of voltage reduction during sputtering cannot be fully obtained. If it can be confirmed that there are more than 10 metal Cr phases in the observation field of 1mm×1mm, it can be said that the metal Cr phase is uniformly dispersed in the entire area of ​​the sputtering target. If the metal Cr phase is greater than 300, multiple bumps appear on the target surface during sputtering due to the difference in sputtering rate, which is prone to problems such as particles and arcs. It should be noted that the incomplete metal Cr phases that appear at the end of the observation field are not counted.

[0049] In the sputtered thin film, Co plays a core role in the formation of magnetic particles of the granular structure. In the Co-Cr-Pt-oxide sputtering target of the present invention, the content of Co relative to the entire target is 50 atomic % or more, preferably 55 atomic % or more, more preferably 60 atomic % or more, preferably 90 atomic % or less, more preferably 80 atomic % or less, and is set within the range of the content required as a recording layer in a magnetic recording medium.

[0050] The content of Pt in the Co-Cr-Pt-oxide sputtering target of the present invention relative to the entire target is greater than 0 atomic % and is less than 25 atomic %, preferably greater than 5 atomic %, more preferably greater than 10 atomic %, preferably less than 23 atomic %, more preferably less than 22 atomic %, and is set within the range of the content required as a recording layer in a magnetic recording medium. In the sputtered thin film, Pt has the function of increasing the magnetic moment of Co by alloying with Co as a magnetic particle structure, and has the effect of adjusting the magnetic strength of the magnetic particles.

[0051] The content of Cr in the Co-Cr-Pt-oxide sputtering target of the present invention is greater than 0 atomic % and less than 20 atomic % relative to the entire target, preferably greater than 1 atomic %, more preferably greater than 3 atomic %, preferably less than 15 atomic %, more preferably less than 10 atomic %, and is set within the range of the content required as a recording layer in a magnetic recording medium. In the sputtered thin film, Cr has the function of reducing the magnetic moment of Co by alloying with Co as a magnetic particle structure, and has the effect of adjusting the magnetic strength of the magnetic particles.

[0052] In the sputtered thin film, the oxide acts as a partition wall that isolates the alloy phases for forming a granular structure. In the Co-Cr-Pt-oxide sputtering target of the present invention, the content of the oxide relative to the entire target is set to more than 20 volume % and less than 50 volume %, preferably set to more than 25 volume %, more preferably set to more than 30 volume % and less than 45 volume %, more preferably set to less than 40 volume %, set to within the range of the content required as a recording layer in a magnetic recording medium.

[0053] The Co-Cr-Pt-oxide sputtering target of the present invention comprises (A) a composite phase in which Co, Pt and oxide are dispersed mutually, and (B) a metal Cr phase. In the (A) composite phase, metals (Co, Cr, Pt, etc.) or alloys and oxides are uniformly dispersed mutually, and from the viewpoint of voltage stability, it is preferred that oxides with high resistance are finely dispersed. The (B) metal Cr phase is a non-magnetic material, and therefore, even if separated from the (A) composite phase, the magnetic properties can be maintained. Although the clear reason is not clear, it is possible to reduce the voltage during sputtering and make the discharge stable, thereby suppressing the occurrence of arcs.

[0054] (A) The oxide contained in the composite phase is preferably an oxide of an element selected from one or any combination of two or more selected from B, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Ta, W, La, Ce, Nd, Sm, and Gd, and preferably contains at least boron oxide. Preferred examples of the oxide include B2O3, SiO2, Co3O4, Cr2O3, CoO, TiO2, Ta2O5, MnO, Mn2O3, Nb2O5, ZnO, WO3, VO2, MgO, ZrO2, Al2O3, and Y2O3.

[0055] (A) The composite phase may further contain one or more selected from B, Al, Si, Ti, V, Mn, Fe, Ni, Cu, Zn, Ge, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Ir and Au. The above-mentioned additive elements are preferably contained in the form of alloys with Co and Pt. In the thin film formed by sputtering, the above-mentioned additive elements have the effect of adjusting the magnetic strength of the magnetic particles by alloying with Co as the magnetic particles of the granular structure. In particular, Ru and B are effective in adjusting the magnetic moment of Co.

[0056] [Second embodiment]

[0057] The Co-Cr-Pt-oxide sputtering target of the second embodiment is a Co-Cr-Pt-oxide sputtering target containing more than 50 atomic % of Co, more than 0 atomic % and less than 20 atomic % of Cr, and more than 0 atomic % and less than 25 atomic % of Pt, and the balance is composed of one or more oxides and unavoidable impurities, characterized in that it contains (A) a composite phase in which Co, Pt and oxides are dispersed mutually, (B) a metal Cr phase, and (C) an alloy phase containing Co or Pt, and contains more than 10 metal Cr phases with an equivalent circle diameter greater than 10 μm and less than 100 μm within an observation field of 1 mm×1 mm using a SEM with an observation magnification of 50 times.

[0058] The sputtering target of the second embodiment is the same as that of the first embodiment except that it further includes (C) an alloy phase containing Co or Pt, and therefore the same description as that of the first embodiment will be omitted.

[0059] In the second embodiment, by including (C) an alloy phase containing Co or Pt, the melting point can be lowered in most cases compared to the substance with the highest melting point among the metal Co or metal Pt and other components constituting the alloy. Since the melting point of the raw material powder is lowered, the sinterability can be improved, resulting in an effect of lowering the sintering temperature. Therefore, when sintering at the same temperature as the sintering temperature when the alloy phase is not included, a sintered body with a higher density can be obtained. On the other hand, by lowering the sintering temperature while maintaining a high density, it is also effective to reduce the manufacturing cost.

[0060] (C) The alloy phase containing Co or Pt is an alloy phase containing Co or Pt as a main component and does not contain oxides. The alloy phase can be set to be selected from a Co alloy phase containing more than 50 atomic %, preferably more than 30 atomic %, and more preferably more than 10 atomic %, a Pt alloy phase containing more than 50 atomic %, preferably more than 30 atomic %, and more preferably more than 10 atomic %, a Co-Pt alloy phase containing more than 50 atomic % of Co and less than 50 atomic % of Pt, and a Co-Pt alloy phase containing less than 50 atomic % of Co and more than 50 atomic % of Pt. One or any combination of two or more. The Co alloy phase or the Pt alloy phase may contain B, Cr, Si, Ti, Ru, Mn, Nb, Zn, W, V, and Ta as other components.

[0061] The sputtering target of the present invention can be manufactured by stirring and mixing Cr metal powder having an average particle size of 150 μm or more and 1000 μm or less, other raw material powders and oxides to prepare a mixed powder for the target and sintering the mixed powder for the target. Alternatively, it can be manufactured by stirring and mixing other raw material powders and oxide powders, then adding Cr metal powder having an average particle size of 10 μm or more and 150 μm or less, preferably 20 μm or more, more preferably 25 μm or more, preferably 100 μm or less, and more preferably 50 μm or less and further stirring and mixing to prepare a mixed powder for the target, and sintering the mixed powder for the target. It should be noted that the metal Cr phase in the sputtering target becomes almost the same size or less than the size of the input Cr metal powder after the stirring and mixing process, but in the process of sintering during the manufacture of the target, the Cr metal powders diffuse and bond with each other, and sometimes there is a metal Cr phase with a particle size larger than the input Cr metal powder.

[0062] The alloy powder may be a powder produced by a gas atomization method. As the alloy powder, for example, Co-Pt alloy, Co-B alloy, Pt-B alloy, Co-Cr-Pt alloy, Co-Ru alloy, Co-Cr-Ru alloy, Co-Si alloy, Co-Cr alloy, Co-Cr-Pt-B alloy, Co-Cr-Pt-Ru alloy, Co-Cr-Pt-Ru-B alloy, etc. may be preferably used.

[0063] Next, each weighed raw material powder is put into a stirring and crushing device such as a ball mill, stirred and mixed, and each raw material powder is uniformly mixed and dispersed to obtain a mixed powder. The stirring and mixing conditions can be appropriately adjusted so that each raw material powder is uniformly mixed and dispersed. For example, when the particle size of the raw material powder is close to the target organization, it is preferred to suppress the crushing. A stirrer or a container rotating type mixing device can be used without using a crushing medium, or a mixing device such as a ball mill using a crushing medium can be used when crushing is required. In addition, in order to form a metal Cr phase with an equivalent circle diameter greater than 10 μm and less than 100 μm, it is preferred to divide the stirring and mixing into two or more stages, and then put in a metal Cr powder with an average particle size of more than 10 μm and less than 150 μm, and slowly stir. In addition, when the Cr content in the design composition of the sputtering target is high, the input of the metal Cr powder can be divided into two or more stages to adjust the number of coarse metal Cr phases present in the sputtering target.

[0064] Next, the sputtering target is sintered with the mixed powder to obtain a sintered body. As for the sintering conditions, as long as a high-density sintered body with a relative density of more than 90% can be obtained, a known sintering method such as hot pressing, spark plasma sintering (SPS), hot isostatic pressing (HIP) can be used. The sintering temperature varies depending on the composition and the properties of the mixed powder, but is generally about 600°C or more and about 1200°C or less for the Co-Cr-Pt-oxide system. It is also possible to increase the temperature while observing the displacement in the pressurization direction during sintering, and use the temperature at which the displacement is stable as the sintering temperature.

[0065] Example

[0066] [Preparation of sputtering target]

[0067] [Example 1]

[0068] 50Co-50Pt alloy powder (sometimes also referred to as "Co-50Pt alloy powder"), Co powder, Cr powder, SiO2 powder, Co3O4 powder, and B2O3 powder were weighed respectively in such a manner as to form the designed composition of the sputtering target of Example 1 shown in Table 1: 63 atom% Co-6 atom% Cr-22 atom% Pt-2 atom% SiO2-1 atom% Co3O4-6 atom% B2O3. For the Co-50Pt alloy powder and Co powder, powders produced by gas atomization were used. For the Co-50Pt alloy powder and Co powder, powders that passed through a sieve with a mesh size of 106 μm were used. For the Cr powder, powders having an average particle size of 35 μm that passed through a sieve with a mesh size of 45 μm were used.

[0069] The powders other than the Cr powder in the weighed powders are put into a ball mill jar and stirred and mixed for the first time until they are fine enough and dispersed with each other. Then, the Cr powder is put into a ball mill jar and stirred and mixed for the second time to obtain a mixed powder for sintering. The second stirring and mixing is controlled in a manner that reduces the input energy compared to the first stirring and mixing and prevents the Cr phase from being refined. Specifically, the total number of revolutions in the second stirring and mixing is set to 1 / 140 relative to the first stirring and mixing. Regarding the stirring and mixing of Examples 2 to 25 described later, the total number of revolutions in the second stirring and mixing is also set to less than 1 / 70 relative to the first stirring and mixing.

[0070] The obtained mixed powder is filled into a carbon mold, and a sintered body is obtained using a hot press. The sintering conditions are set to a vacuum atmosphere, a sintering temperature of 750°C, and a holding time of 1 hour. It should be noted that in order to obtain a high density with a relative density of more than 95%, the temperature is increased while observing the displacement in the pressurization direction during sintering, and the temperature at which the displacement is stable is taken as the sintering temperature. The relative density of the obtained sintered body was measured by the Archimedean method, and it was confirmed that a high-density sintered body with a relative density of 99% was obtained. By performing external shaping on the sintered body, a sputtering target with a diameter of 165 mm and a thickness of 6.4 mm was produced. For Examples 2 to 25 and Comparative Examples 1 to 19 described later, the sintering temperature is also determined by the same method, which is 650°C to 1200°C.

[0071] [Example 2]

[0072] In Example 2, a sputtering target was produced in the same manner as in Example 1 except that the input energy during the second stirring and mixing was increased.

[0073] [Example 3]

[0074] In Example 3, except that the input energy during the second stirring and mixing was increased compared with that in Example 2, the same operation as in Example 1 was carried out to produce a sputtering target.

[0075] [Example 4]

[0076] For the Cr powder in the raw material powder, a large powder that passed through a sieve with a mesh of 1000 μm and did not pass through a sieve with a mesh of 150 μm was used, and all the raw material powders were put into a ball mill pot together, and stirred and mixed once using a ball mill to obtain a mixed powder. The obtained mixed powder was sintered in the same manner as in Example 1 to make a sputtering target.

[0077] [Comparative Example 1]

[0078] The same raw material powders as in Example 1 were all put into a ball mill pot, and stirred and mixed once using a ball mill to obtain a mixed powder. The obtained mixed powder was sintered in the same manner as in Example 1 to produce a sputtering target.

[0079] [Example 5]

[0080] A sputtering target was produced in the same manner as in Example 1 except that Pt powder having passed through a sieve with an opening of 106 μm was used instead of the Co-50Pt alloy powder in the raw material powder.

[0081] [Comparative Example 2]

[0082] A sputtering target was produced in the same manner as in Comparative Example 1, except that Pt powder having passed through a sieve with an opening of 106 μm was used instead of the Co-50Pt alloy powder in the raw material powder.

[0083] [Examples 6 to 25]

[0084] Each raw material powder was weighed so as to obtain the designed composition of the sputtering target shown in Examples 6 to 25 of Table 1, and the sputtering target was produced in the same manner as in Example 1. Examples 9 and 15 used Pt powder that passed through a sieve with a mesh size of 106 μm instead of Co-50Pt alloy powder. Example 17 used Co-18.5B alloy powder instead of B powder. Example 24 used Co-90Pt alloy powder instead of Co-50Pt alloy powder. Example 25 used Co-10Pt alloy powder instead of Co-50Pt alloy powder.

[0085] [Comparative Examples 3 to 22]

[0086] Each raw material powder was weighed so as to obtain the sputtering target design composition shown in Comparative Examples 3 to 22 of Table 1, and a sputtering target was produced in the same manner as in Comparative Example 1. Comparative Examples 6 and 12 used Pt powder that passed through a sieve with a mesh size of 106 μm instead of Co-50Pt alloy powder. Comparative Example 14 used Co-18.5B alloy powder instead of B powder. Comparative Example 21 used Co-90Pt alloy powder instead of Co-50Pt alloy powder. Comparative Example 22 used Co-10Pt alloy powder instead of Co-50Pt alloy powder.

[0087] [Organizational Analysis]

[0088] A sample piece for structural observation was cut out from the obtained sputtering target, and the cross section was mirror-polished. Then, for each phase contained therein, the main components were analyzed by EDX composition mapping. The results of Example 1 are shown in FIG. Figure 2 It was confirmed that the sputtering target cross section contained a composite phase in which metal and oxide were finely dispersed ( Figure 2 Gray parent phase), Co-Pt alloy phase ( Figure 2 white phase) and metallic Cr phase ( Figure 2 The black phase). Regarding the metallic Cr phase, for the phase mainly detected only by Cr in the composition mapping, the weight ratio of the target composition was quantitatively analyzed, and it was confirmed that it was composed of Cr and inevitable impurities. Next, an image of a 1mm×1mm field of view at an observation magnification of 50 times was obtained using SEM, and the metallic Cr phase was binarized into black and other phases were binarized into white using image analysis software. Further, only the metallic Cr phases with equivalent circle diameters from the largest side to the tenth largest were extracted, and the equivalent circle diameters of the largest metallic Cr phase and the tenth largest metallic Cr phase were calculated. The image of Example 1 is shown in Figure 3 In the example 1, the results are shown. Figure 3 The equivalent circle diameter of the tenth largest metal Cr phase from the largest side is 37 μm, and the equivalent circle diameter of the largest metal Cr phase is 50 μm. When the number of metal Cr phases that can be confirmed is less than 10, it cannot be measured and is marked as "-" in Table 1.

[0089] As a result of the microstructure observation of the sputtering target cross section, no metallic Cr phase having an equivalent circle diameter greater than 10 μm and less than 100 μm was confirmed in Comparative Examples 1 to 22. As a representative example, a microstructure photograph of the target cross section of Comparative Example 1 is shown in FIG. Figure 4 The target cross section structure photograph of Comparative Example 2 is shown in Figure 5 .

[0090] In Examples 5, 9, and 15, no Co-Pt alloy phase was confirmed, and only (A) a composite phase consisting of Co, Pt, and oxides and (B) a metal Cr phase were confirmed. The equivalent circle diameter of the 10th largest metal Cr phase was greater than 10 μm, and the equivalent circle diameter of the largest metal Cr phase was less than 100 μm. As a representative example, the microstructure photograph of the target cross section of Example 5 is shown in FIG. Figure 6 middle.

[0091] In Examples 1 to 4, 6 to 8, 10 to 14, and 16 to 25, (A) a composite phase consisting of Co, Pt, and an oxide, (B) a metal Cr phase, and (C) a Co-Pt alloy phase can be confirmed. The equivalent circle diameter of the tenth largest metal Cr phase is greater than 10 μm, and the equivalent circle diameter of the largest metal Cr phase is less than 100 μm.

[0092] [Leakage flux density]

[0093] The leakage flux density (PTF) of the obtained sputtering target was measured based on ASTM F2086-01. In the evaluation of the leakage flux density, the leakage flux density measured by a sputtering target (comparative example) with the same composition but without the metal Cr phase was used as a reference, and the case where the leakage flux density can be maintained with a decrease of less than -2% or the case where it exceeds the reference is judged as good, which is indicated by "0" in Table 1. In Examples 1 to 25, it can be confirmed that the PTF is equal to or improved compared with the corresponding comparative examples of the same composition.

[0094] [Sputtering discharge voltage]

[0095] The obtained sputtering target is installed in a magnetron sputtering device, and while the argon gas is made to flow at a pressure of 1.0 Pa, sputtering discharge is continuously performed with an input power of 1000 W, and the sputtering discharge voltage is measured using a data recorder. The setting conditions of the data recorder are set to repeat the operation of measuring 15,000 points of data with a sampling period of 2 μ seconds 100 times. The average value of the data measured each time is calculated, and the average value is averaged 100 times to calculate the sputtering discharge voltage value under the measurement conditions. When the sputtering discharge voltage value can be reduced by more than 20V relative to the sputtering target (comparative example) with the same composition but without the metal Cr phase, it is judged that the discharge stability is improved. In Examples 1 to 25, it can be confirmed that the discharge voltage difference with the corresponding comparative examples of the same composition is more than 20V lower.

[0096] [Relative density]

[0097] In all the Examples and Comparative Examples, the relative density of the sputtering target was 95% or more.

[0098]

Claims

1. A sputtering target, which is a Co-Cr-Pt-oxide sputtering target containing 50 atomic % or more of Co, more than 0 atomic % and less than 20 atomic % of Cr, and more than 0 atomic % and less than 25 atomic % of Pt, and the balance is composed of one or more oxides and unavoidable impurities, characterized in that: It contains (A) a composite phase in which Co, Pt and oxide are dispersed mutually and (B) a metallic Cr phase. Ten or more metal Cr phases having an equivalent circle diameter greater than 10 μm and less than 100 μm are included in a 1 mm×1 mm observation field of view using an SEM with an observation magnification of 50 times.

2. A sputtering target, which is a Co-Cr-Pt-oxide sputtering target containing 50 atomic % or more of Co, more than 0 atomic % and less than 20 atomic % of Cr, and more than 0 atomic % and less than 25 atomic % of Pt, and the balance is composed of one or more oxides and unavoidable impurities, characterized in that: The invention comprises (A) a composite phase in which Co, Pt and oxide are dispersed mutually, (B) a metal Cr phase, and (C) an alloy phase containing Co or Pt, Ten or more metal Cr phases having an equivalent circle diameter greater than 10 μm and less than 100 μm are included in a 1 mm×1 mm observation field of view using an SEM with an observation magnification of 50 times.

3. The sputtering target according to claim 1 or 2, characterized in that: The composite phase also contains one or more selected from B, Al, Si, Ti, V, Mn, Fe, Ni, Cu, Zn, Ge, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Ir and Au.

4. The sputtering target according to claim 1 or 2, characterized in that: The sputtering target contains 20 volume % or more and 50 volume % or less of the oxide.

5. The sputtering target according to claim 1 or 2, characterized in that: The oxide is an oxide of an element selected from one or any combination of two or more of B, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Ta, W, La, Ce, Nd, Sm, and Gd.

6. The sputtering target according to claim 1 or 2, characterized in that: The oxide includes at least boron oxide.

7. The sputtering target according to claim 1 or 2, characterized in that: The composite phase further contains one or more selected from B, Al, Si, Ti, V, Mn, Fe, Ni, Cu, Zn, Ge, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Ir and Au, and The oxide includes at least boron oxide and an oxide of an element selected from one or any combination of two or more of Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Ta, W, La, Ce, Nd, Sm, and Gd.

8. A method for producing a sputtering target, which is the method for producing a sputtering target according to claim 1 or 2, characterized in that: A target mixed powder is prepared by mixing and stirring raw material powders including a Cr metal powder and an oxide powder having an average particle size of 150 μm or more and 1000 μm or less, The target mixed powder is sintered.

9. A method for producing a sputtering target, which is the method for producing a sputtering target according to claim 1 or 2, characterized in that: A Cr metal powder having an average particle size of 10 μm or more and 150 μm or less is added to a mixed powder of other raw material powders and oxide powders that have been mixed and stirred in advance to prepare a mixed powder for a target. The target mixed powder is sintered.

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