JP6728094B2 - Ferromagnetic material sputtering target - Google Patents

Description

The present invention relates to a Co—Pt based ferromagnetic material sputtering target suitable for forming a magnetic thin film in a magnetic recording medium.

In the field of magnetic recording represented by a hard disk drive, a material based on Co, which is a ferromagnetic metal, is used as a material of a magnetic thin film that is responsible for recording.

A magnetic thin film is often produced by sputtering a sputtering target containing the above material as a component with a DC magnetron sputtering device in terms of high productivity. However, when a ferromagnetic material sputtering target is used for sputtering in a magnetron sputtering device, most of the magnetic flux from the magnet passes through the inside of the target, which is a ferromagnetic material, so the leakage magnetic flux is reduced and discharge does not occur during sputtering. Or, there arises a problem that the discharge is not stable even if it is discharged. In order to solve this problem, it can be considered to reduce the content ratio of Co which is a ferromagnetic metal. However, if Co is reduced, it is not an essential solution because the desired magnetic recording film cannot be obtained. Further, it is possible to improve the leakage magnetic flux by reducing the thickness of the target, but in this case, the target life becomes short and it becomes necessary to replace the target frequently, which causes a cost increase.

Therefore, conventionally, a method of increasing the Cr ratio to partially make it non-magnetic to increase the leakage magnetic flux has been adopted. For example, a Co—Cr-based or Co—Cr—Pt-based ferromagnetic alloy containing Co as a main component has been used for a recording layer of a hard disk adopting an in-plane magnetic recording method. Further, in a recording layer of a hard disk adopting a perpendicular magnetic recording system which has been put into practical use in recent years, a non-magnetic particle such as oxide or carbon is dispersed in a Co—Cr—Pt type ferromagnetic alloy containing Co as a main component. Many composite materials are used. However, the recent mainstream composition is a composition containing little or no Cr, and it is difficult to sufficiently obtain the effect of increasing the leakage flux by the conventional method.

From such a background, in WO2012/077665, in a sputtering target composed of a metal having a composition of Pt of 5 mol% or more, Cr of 20 mol% or less and the balance of Co, the metal base (A) and the (A) Among them, a ferromagnetic material sputtering target characterized by having a Co—Pt alloy phase (B) containing 40 to 76 mol% of Pt is proposed. According to this document, if the diameter of the Co—Pt alloy phase (B) is too small, the diffusion between the metal base (A) and the phase (B) proceeds and the difference in the constituent elements becomes unclear. It is preferably 10 μm or more. Further, according to the document, if the diameter of the Co—Pt alloy phase (B) is too large, the problem of particles during sputtering tends to occur, so it is desirable that the diameter is 150 μm or less.

Further, in WO2012/081669, in a sputtering target composed of a metal having a composition of Cr of 20 mol% or less, Pt of 5 mol% or more, and the balance of Co, the metal base (A) and the (A) are A ferromagnetic material characterized by having a Co-Pt alloy phase (B) containing 40 to 76 mol% of Pt and Co or a metal or alloy phase (C) containing Co as a main component different from the phase (B). Sputtering targets have been proposed. According to this document, if the diameter of the Co—Pt alloy phase (B) is too small, the diffusion between the metal base (A) and the phase (B) proceeds and the difference in the constituent elements becomes unclear. It is preferably 10 μm or more. Further, according to the document, if the diameter of the Co—Pt alloy phase (B) is too large, the problem of particles during sputtering is likely to occur, so it is desirable that the diameter is 150 μm or less.

WO2012/077665 WO2012/081669

As described in Patent Document 1 and Patent Document 2, a ferromagnetic material sputtering target having a Co—Pt alloy phase in the metal matrix has an advantage that leakage flux can be increased. However, according to the examination result of the present inventor, the sputtering target still has room for improvement regarding suppression of particles during sputtering. Therefore, it is an object of the present invention to provide a Co—Pt based ferromagnetic material sputtering target which has a high leakage magnetic flux and can suppress the generation of particles during sputtering.

Although Patent Documents 1 and 2 teach that the Co—Pt alloy phase should be a phase having a diameter of 10 μm or more, such a coarse Co—Pt alloy phase is a particle of particles during sputtering. It turned out to be the cause of the outbreak. Therefore, the present inventor diligently studied an effective means for suppressing particles while taking advantage of the advantage of the Co—Pt alloy phase capable of increasing the leakage magnetic flux. As a result, the Co phase was coarsened while the Co phase was made finer. It was found that the method of making it effective is effective. The present invention has been completed based on these findings.

According to one aspect of the present invention,
Co:Pt=X:100-X (59≦X<100) at a molar ratio of a metal Co and a metal Pt in a total amount of 70 mol% or more and a metal Cr content of 0 mol% or more and 20 mol% or less. The target,
A Co particle phase containing 90 mol% or more of metallic Co and having an average particle size of 30 to 300 μm,
A Co-Pt alloy containing metallic Co and metallic Pt in a total amount of 70 mol% or more and having an average particle size of 7 μm or less under the condition of Co:Pt=Y:100-Y (20≦Y≦60.5) in a molar ratio. It is a ferromagnetic material sputtering target having a particle phase.

In one embodiment of the ferromagnetic material sputtering target according to the present invention, one selected from the group consisting of B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Al, Si and Zn, or It contains 30 mol% or less in total of two or more kinds of third elements.

In another embodiment of the ferromagnetic material sputtering target according to the present invention, one or more non-magnetic materials selected from the group consisting of carbon, oxides, nitrides, carbides and carbonitrides in total. Contains 25 mol% or less.

In still another embodiment of the ferromagnetic material sputtering target according to the present invention, in the XRD measurement in which the measurement range of 2θ is 30° to 60°, 33.27±2°, 41.52±2°, 47. It has peaks at positions of .76±2°, 49.44±2°, and 54.21±2°.

In another aspect of the present invention,
A step of preparing Co powder containing 90 mol% or more of metallic Co and having a median diameter of 30 to 300 μm;
A Co-Pt alloy having a median diameter of 7 [mu]m or less, containing metallic Co and metallic Pt in a total amount of 70 mol% or more under the condition of Co:Pt=Y:100-Y (20≤Y≤60.5) in molar ratio. A step of preparing powder,
Co—Pt alloy powder and Co powder are mixed, and the total content of metallic Co and metallic Pt is 70 mol% or more under the condition that the molar ratio is Co:Pt=X:100−X (59≦X<100). A step of obtaining a mixed powder containing metallic Cr of 0 mol% or more and 20 mol% or less,
Baking the mixed powder,
Is a method of manufacturing a ferromagnetic material sputtering target including.

In one embodiment of the method for manufacturing a ferromagnetic material sputtering target according to the present invention, the step of obtaining the mixed powder further includes B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Al, Mixing one or more powders selected from the group consisting of Si and Zn.

In another embodiment of the method for manufacturing a ferromagnetic material sputtering target according to the present invention, the step of obtaining the mixed powder is further selected from the group consisting of carbon, oxide, nitride, carbide and carbonitride. It includes mixing one or more non-magnetic materials.

In still another embodiment of the method for manufacturing a ferromagnetic material sputtering target according to the present invention, the step of preparing a Co—Pt alloy powder having a median diameter of 10 μm or less includes Co:Pt=Y:100-Y(20 In the XRD measurement in which a powder obtained by mixing Co powder and Pt powder in a molar ratio of ≦Y≦60.5) is fired at a heating temperature of 800° C. to 1000° C. and a measurement range of 2θ is 30° to 60°, 2θ=33.27±2°, 41.52±2°, 47.76±2°, 49.44±2°, and first sintered body having peaks at respective positions of 54.21±2° And a step of crushing the first sintered body.

The present invention, in yet another aspect, is a method for producing a magnetic recording film, which comprises using the sputtering target according to the present invention.

The ferromagnetic material sputtering target of the present invention becomes a target with a large leakage magnetic flux, and when used in a magnetron sputtering apparatus, the promotion of ionization of an inert gas proceeds efficiently and a stable discharge can be obtained. According to the present invention, it is possible to increase the thickness of the target, which reduces the frequency of replacement of the target and has the advantage that the magnetic thin film can be manufactured at low cost. Further, the ferromagnetic material sputtering target of the present invention has few particles at the time of sputtering and enables stable sputtering.

The XRD profile of the comparative example 1 is shown. 4 shows an XRD profile of Comparative Example 2. The XRD profile of the comparative example 3 is shown. 3 shows an XRD profile of Example 1. 3 shows an XRD profile of Example 2. 7 shows an XRD profile of Example 3. 8 shows an XRD profile of Example 5. 8 shows an XRD profile of Example 7.

(1. Overall composition)
In one embodiment, the ferromagnetic material sputtering target according to the present invention has a molar ratio of Co:Pt=X:100−X (59≦X<100), and the total amount of metallic Co and metallic Pt is 70 mol% or more. The content of Cr is 0 mol% or more and 20 mol% or less. Since the composition has a large content of the metal Co, which is a ferromagnetic material, and a small content of the metal Cr, which has an effect of increasing the leakage magnetic flux, it is generally difficult to obtain a high leakage magnetic flux. According to the present invention, with respect to a sputtering target having a composition in which a high leakage magnetic flux is hard to be obtained, it is possible to increase the leakage magnetic flux and further reduce particles by devising the structure of the target.

The ferromagnetic material sputtering target according to the present invention can be set to 70≦X≦90 in one embodiment and 80≦X≦85 in another embodiment in consideration of a hard disk media manufacturing application. it can.

The ferromagnetic material sputtering target according to the present invention may contain metal Co and metal Pt in a total amount of 75 mol% or more in one embodiment, and metal Co and metal Pt in a total amount of 85 mol% or more in another embodiment. can do. Further, the ferromagnetic material sputtering target according to the present invention may contain metal Co and metal Pt in a total amount of 95 mol% or less in one embodiment, and metal Co and metal Pt in a total amount of 90 mol% in another embodiment. The following can be contained. A ferromagnetic material sputtering target containing a total of 75 to 95 mol% of metal Co and metal Pt is suitable for a perpendicular magnetic recording film.

The ferromagnetic material sputtering target according to the present invention may contain 0 mol% or more and 15 mol% or less of metal Cr in one embodiment, and may contain 0 mol% or more and 10 mol% or less of metal Cr in another embodiment. In yet another embodiment, the metal Cr can be contained in an amount of 0 mol% or more and 5 mol% or less, and in yet another embodiment, the metal Cr can be included in an amount of 0 mol% or more and 1 mol% or less. In the form, it does not contain metallic Cr.

(2. Co-Pt alloy particle phase)
In order to increase the leakage magnetic flux in the sputtering target having such a Co-rich composition, the sputtering target contains metallic Co and metallic Pt at a molar ratio of Co:Pt=Y:100-Y (20≦Y≦60.5). It is desirable to have a Co-Pt alloy particle phase containing 70 mol% or more in total, preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 99 mol% or more. The Co—Pt alloy particle phase can form an ordered phase having an L1 ₀ structure and exhibit high magnetic anisotropy, thus contributing to an increase in leakage magnetic flux. From the viewpoint of increasing the leakage magnetic flux, preferably 25≦Y≦55, more preferably 34.5≦Y≦55, and even more preferably 40≦Y≦50. The Co-Pt alloy particle phase can exist in a dispersed state in the target structure.

Although the Co-Pt alloy particle phase contributes to the improvement of the leakage magnetic flux, it becomes a factor to increase the particles when the average particle diameter is large. In Patent Documents 1 and 2, the problem of particles during sputtering due to the Co—Pt alloy particle phase is said to occur when the diameter exceeds 150 μm, but the Co—Pt alloy particle phase is as fine as possible. Is desirable. Therefore, in the ferromagnetic material sputtering target according to the present invention, the average particle size of the Co—Pt alloy particle phase is preferably 7 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less. preferable. However, if the average particle size of the Co—Pt alloy particle phase is too small, diffusion with other phases is promoted during sintering and the possibility of losing the L1 ₀ structure increases, so the average particle size is 0.1 μm or more. Preferably, it is 0.2 μm or more, more preferably 0.5 μm or more, and even more preferably 0.5 μm or more.

From the viewpoint of enhancing the effect of increasing the leakage magnetic flux, the Co-Pt alloy particle phase is preferably 20% by mass or more, and more preferably 30% by mass or more, with respect to the total mass of the sputtering target. Is more preferably 40% by mass or more. Further, the Co-Pt alloy particle phase is preferably 70% by mass or less, and preferably 65% by mass or less, with respect to the total mass of the sputtering target, from the viewpoint of finely dispersing the non-magnetic material. More preferably, it is even more preferably 60% by mass or less.

(3. Co particle phase)
In one embodiment, the sputtering target having a Co-rich composition according to the present invention has a Co particle phase containing 90 mol% or more of metallic Co in addition to the Co—Pt alloy particle phase. In order to increase the ratio of the Co—Pt alloy particle phase contained in the target, the Co particle phase preferably contains metallic Co in an amount of 95 mol% or more, and more preferably 99.9 mol% or more. The Co particle phase can exist in a dispersed manner in the target structure.

When the Co-Pt alloy particle phase is miniaturized, if the Co particle phase is also miniaturized, the number of contact points with the Co-Pt alloy particle phase increases, diffusion of the constituent elements is promoted during sintering, and the L1 ₀ structure is lost. The problem arises. Therefore, it is desirable to coarsen the Co particle phase. Specifically, the average particle size of the Co particle phase containing 90 mol% or more of metallic Co is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more. However, the average particle size of the Co particle phase is preferably 300 μm or less, more preferably 200 μm or less, and more preferably 150 μm or less, because if it is too large, it may cause generation of particles. It is even more preferable.

Since the Co particle phase increases the leakage magnetic flux, and from the viewpoint of further suppressing the diffusion of the Co—Pt alloy particle phase during sintering, it is 15% by mass or more with respect to the total mass of the sputtering target. It is more preferably 25% by mass or more, still more preferably 30% by mass or more. In addition, since the Co particle phase is coarse particles, it is preferably 50% by mass or less with respect to the total mass of the sputtering target from the viewpoint of improving dispersibility with other raw materials during mixing, and 45 mass% % Or less, and more preferably 40% by mass or less.

(4. Third element)
The ferromagnetic material sputtering target according to the present invention is, as the third element, one selected from the group consisting of B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Al, Si and Zn, or A total of 30 mol% or less, for example, 0.01 to 20 mol%, typically 0.05 to 10 mol%, may be contained as a single metal or alloy of two or more kinds. These are elements added as necessary in order to improve the characteristics of the magnetic recording medium. The mixing ratio can be variously adjusted within the above range, and any of them can maintain the characteristics as an effective magnetic recording medium. In the present invention, B is also treated as a metal.

The third element may be present in the Co-Pt alloy particle phase or may be present in the Co particle phase, and is a particle phase different from the Co-Pt alloy particle phase and the Co particle phase. Can exist inside. The separate particle phase can be present dispersed in the target tissue. However, the third element is present in the Co—Pt alloy particle phase or in another fine particle phase because the finer dispersion is more advantageous for particle reduction. Is preferably present. Incidentally, when the third element is not a particle phase of a simple metal or alloy, but forms a particle phase as an oxide, a nitride, a carbide or a carbonitride, it is not the particle phase of the third element and will be described later. Treated as the particle phase of magnetic materials.

When the third element is present in another particle phase, the other particle phase preferably forms a composite phase in which the Co-Pt alloy particle phase is mutually dispersed. Further, when a particle phase of a non-magnetic material described later is further present, the other particle phase may form a composite phase in which the Co-Pt alloy particle phase and the particle phase of the non-magnetic material are mutually dispersed. preferable. When the third element forms another particle phase, the average particle diameter of the particle phase of the third element is preferably 20 μm or less, more preferably 10 μm or less, and 5 μm or less. Are even more preferred. However, the average particle size of the particle phase of the third element is preferably 0.5 μm or more, because if the average particle size of the particle phase of the third element is too small, oxidation may proceed due to oxygen in the atmosphere during the mixed powder preparation process. And more preferably 2 μm or more.

(5. Non-magnetic material)
The ferromagnetic material sputtering target according to the present invention contains, as an additive material, one or more non-magnetic materials selected from the group consisting of carbon, oxides, nitrides, carbides and carbonitrides in total of 25 mol% or less, For example, the content may be 5 to 20 mol %, typically 5 to 15 mol %. In this case, the sputtering target can have characteristics suitable for the material of the magnetic recording film having the granular structure, particularly the recording film of the hard disk drive adopting the perpendicular magnetic recording system.

Examples of the carbide include one or two or more kinds of carbides selected from the group consisting of B, Ca, Nb, Si, Ta, Ti, W and Zr. Examples of oxides include Si, Al, B, Ba, Be, Co, Ca, Ce, Cr, Dy, Er, Eu, Ga, Gd, Ho, Li, Mg, Mn, Nb, Nd, Pr, Sc. Oxides of one or more elements selected from the group consisting of Sm, Sr, Ta, Tb, Ti, V, Y, Zn and Zr. Among the oxides, SiO ₂ has a large effect of contributing to increasing the density of the sputtering target, and therefore it is preferable to add SiO ₂ . Examples of the nitride include one or more nitrides of elements selected from the group consisting of Al, Ca, Nb, Si, Ta, Ti and Zr. These non-magnetic materials may be added appropriately according to the required magnetic properties of the magnetic thin film. The Cr oxide and Co oxide are recognized as different from Cr and Co added as metals.

The non-magnetic material can be present as a particle phase of the non-magnetic material that is distinguishable from the Co-Pt alloy particle phase and the Co particle phase in a dispersed state in the target structure. In that case, the average particle diameter of the particle phase of the non-magnetic material is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less. However, the average particle size of the particle phase of the non-magnetic material is 0.05 μm or more, because if it is too small, there is a risk of agglomeration with each other during the mixed powder preparation process to form lumps (coarse secondary particles). The thickness is preferably 0.1 μm or more, more preferably 0.2 μm or more.

(6. XRD profile)
In one embodiment, the ferromagnetic material sputtering target according to the present invention is 33.27±2°, 41.52±2°, 47.76±2 in XRD measurement in which the measurement range of 2θ is 30° to 60°. There are peaks at respective positions of °, 49.44±2°, and 54.21±2°. Since the sputtering target has such an XRD profile, it is possible to further increase the leakage magnetic flux. Although the present invention is not intended to be limited by theory, the above-mentioned peaks are derived from the L1 ₀ structure, and the composition of the sputtering target according to the present invention shows that the Co—Pt alloy particle phase is L1 _0. It is presumed that such a peak is observed when the ordered phase of the structure is formed.

2θ=33.27±2°, 41.52±2°, 47.76±2°, 49.44±2°, and 54.21±2° have a peak at each position. It means that the ratio of the peak intensity to the background intensity (average value of the intensity of 2θ=37.0 to 38.0°) in 2 is 2 or more, and the ratio can be generally set to 2 to 200.

In particular, since it is necessary for the L1 ₀ structure to be firmly formed in order to increase the leakage magnetic flux, the strongest peak at 41 in the measurement range of 2θ of 30° to 60° in XRD measurement is 41.52. It is preferably present at ±2°. 41.52 ± 2 ° is a strongest peak of L1 ₀ structure of Co-Pt.

In the present invention, the XRD measurement of the sputtering target is measured under the following conditions. An X-ray diffractometer (Ultima IV manufactured by Rigaku Co., Ltd. was used as a measuring device) was used as a measuring device, a tube was Cu, measuring conditions were a tube voltage of 40 kv, a tube current of 30 mA, a scan speed of 4°/min, and a step of 0.02. And is measured on a surface horizontal to the sputtering surface by the θ/2θ method. It may be a surface or a cut surface as long as it is a surface horizontal to the sputtering surface.

(7. Manufacturing method)
The ferromagnetic material sputtering target according to the present invention can be manufactured by the following procedure using the powder sintering method.

A Co powder having a purity of 90 mol% or more, preferably 95 mol% or more, more preferably 99.9 mol% or more is prepared. The Co powder may be produced by crushing an ingot of melt-cast metallic cobalt, or may be produced by a gas atomizing method. The median diameter of the Co powder is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more. However, the median diameter of the Co powder is preferably 300 μm or less, because if it is too large, it may be difficult to uniformly mix it with other powder materials or particles may be caused during sputtering. It is more preferably 200 μm or less, and even more preferably 150 μm or less. The median diameter can be adjusted by crushing or sieving.

In addition, under the condition that the molar ratio is Co:Pt=Y:100-Y (20≦Y≦60.5), the total amount of metallic Co and metallic Pt is 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol. % Or more, and more preferably 99 mol% or more, of a Co—Pt alloy powder is prepared. From the viewpoint of developing the L1 ₀ structure, the median diameter of the Co—Pt alloy powder is preferably 7 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. However, the median diameter of the Co—Pt alloy powder is preferably 0.1 μm or more, and 0.5 μm, because if it is too small, there is a concern that it may be oxidized by oxygen in the atmosphere during the mixing step. More preferably, it is more preferably 1 μm or more.

As a method for producing such a Co-Pt alloy powder, a powder obtained by mixing Co powder and Pt powder in a molar ratio of Co:Pt=Y:100-Y (20≤Y≤60.5) is inert. There is a method of firing at a heating temperature of 800° C. to 1000° C. in an atmosphere. According to the firing method, in the XRD measurement in which the measurement range of 2θ was 30° to 60°, 2θ=33.27±2°, 41.52±2°, 47.76±2°, 49.44±2° , And a Co—Pt alloy sponge having a peak at each position of 54.21±2° can be obtained. Examples of the inert atmosphere include vacuum atmosphere, rare gas atmosphere such as Ar gas atmosphere, and nitrogen gas atmosphere. The median diameter can be adjusted by sieving the powder obtained by crushing the obtained sponge.

Next, a Co-Pt alloy powder and a Co powder are mixed, and a mixed powder containing a total of 70 mol% or more of metal Co and metal Pt in a molar ratio of Co:Pt=X:100-X (59≦X<100). To get

Prepare powders of one or more third elements selected from the group consisting of B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Al, Si and Zn, as needed. To do. The powder of the third element is preferably added so that the total concentration in the mixed powder becomes the predetermined concentration in the above-mentioned sputtering target. The median diameter of the powder of the third element is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. However, if the median diameter of the powder of the third element is too small, there is a concern that oxygen in the atmosphere may promote oxidation during the mixed powder preparation process, so it is preferably 0.5 μm or more, and 1 μm or more. It is more preferable, and it is even more preferable that the thickness is 2 μm or more.

If necessary, powder of one or more non-magnetic materials selected from the group consisting of carbon, oxides, nitrides, carbides and carbonitrides is prepared. The powder of the non-magnetic material is preferably added so that the total concentration in the mixed powder becomes the predetermined concentration in the above-mentioned sputtering target. The median diameter of the non-magnetic material powder is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less. However, the median diameter of the powder of the non-magnetic material is preferably 0.05 μm or more, and 0.1 μm or more, because if the median diameter of the powder is too small, there is a concern that oxygen in the atmosphere may promote oxidation during the mixed powder preparation process. Is more preferable and 0.2 μm or more is even more preferable.

If necessary, further Cr powder is prepared. When Cr powder is added, care should be taken so that the total concentration of metallic Cr in the mixed powder falls within the predetermined concentration range in the sputtering target described above. The median diameter of the Cr powder is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. However, the median diameter of the Cr powder is preferably 1 μm or more, more preferably 1.5 μm or more, because if the median diameter of the Cr powder is too small, oxidation in the air may proceed during the mixed powder preparation process. It is even more preferably 2 μm or more.

The median diameter in each of the above raw material powders means the particle diameter at an integrated value of 50% (D50) on the volume value basis in the particle size distribution obtained by the laser diffraction/scattering method. In the examples, a particle size distribution analyzer of model LA-920 manufactured by HORIBA was used, and the powder was dispersed in a solvent of ethanol, and the measurement was carried out by a wet method. As the refractive index, the value of metallic cobalt was used.

The above raw material powders are weighed so as to have a desired composition, and are mixed for pulverization using a known method such as a ball mill. At this time, it is desirable to suppress the oxidation of the raw material powder as much as possible by sealing an inert gas in the crushing container. Examples of the inert gas include Ar and N ₂ gas.

The mixed powder thus obtained is molded and sintered by a hot pressing method in a vacuum atmosphere or an inert gas atmosphere. In addition to the hot pressing method, various pressure sintering methods such as plasma discharge sintering method can be used. In particular, the hot isostatic pressing method (HIP) is effective for improving the density of the sintered body, and it is preferable to carry out the hot pressing method and the hot isostatic pressing method in this order. It is preferable from the viewpoint of improvement.

The holding temperature during sintering is preferably set to the lowest temperature in the temperature range in which the target is sufficiently densified. Although it depends on the composition of the target, in most cases, the temperature may be maintained in the temperature range of 700 to 1200°C. From the viewpoint of increasing the number of ordered phases of the L1 ₀ structure within the temperature range, the holding temperature during sintering is preferably 1050° C. or lower, more preferably 1000° C. or lower, and 950° C. or lower. It is even more preferable to do so. The pressure during sintering is preferably 300 to 500 kg/cm ² . The holding temperature at the time of hot isostatic pressing depends on the composition of the sintered body, but in most cases, it is in the temperature range of 700 to 1200°C. From the viewpoint of increasing the number of ordered phases of the L1 ₀ structure within the temperature range, the temperature is preferably 1050° C. or lower, more preferably 1000° C. or lower, and even more preferably 950° C. or lower. Moreover, it is preferable to set the applied pressure to 100 MPa or more.

The sintering time is preferably 0.3 hours or more, more preferably 0.5 hours or more, and even more preferably 1.0 hour or more in order to improve the density of the sintered body. Further, the sintering time is preferably 3.0 hours or less, more preferably 2.0 hours or less, and further preferably 1.5 hours or less in order to prevent coarsening of crystal grains. Is more preferable.

The sputtering target according to the present invention can be produced by molding the obtained sintered body into a desired shape using a lathe or the like. The target shape is not particularly limited, and examples thereof include a flat plate shape (including a disk shape and a rectangular plate shape) and a cylindrical shape. The sputtering target according to the present invention is particularly useful as a sputtering target used for forming a magnetic recording film.

Hereinafter, examples of the present invention will be shown together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the present invention. ..

(1. Preparation of sputtering target)
As the raw material powder, Co powder, Pt powder, Co—Pt alloy powder, Cr powder, B ₂ O ₃ powder, TiO ₂ powder, SiO ₂ powder, Co ₃ O ₄ powder, Cr _{2 having} each median diameter shown in Table 1 are used. O ₃ powder, B powder, Ru powder, Ta powder, Ta ₂ O ₅ powder, CoO powder, Si ₃ N ₄ powder, and SiC powder were prepared. All of them are high-purity products and contain no impurities other than unavoidable impurities. The median diameter of these powders was screened and appropriately adjusted.

Among the above raw material powders, Co—Pt alloy powder was prepared by the following procedure. Rotate Co powder having a median diameter of 3 μm and Pt powder having a median diameter of 2 μm for 2 hours using an automatic mortar so that the Co molar ratio (Y) in the Co—Pt alloy powder becomes the value described in Table 3. Mixed. Next, the obtained mixed powder was fired for 2 hours in a vacuum atmosphere at the preheat treatment temperature shown in Table 5 according to the test number. Next, the obtained sponge was crushed to obtain a powder obtained by sieving to obtain Co-Pt alloy powder having various median diameters shown in Table 1. However, the Co-Pt powder in Comparative Example 3 was used after being screened by a gas atomizing method.

Next, the above raw material powders were placed in a ball mill pot with a capacity of 10 liters together with the zirconia balls as the grinding media at the mass ratios shown in Table 2 so that the molar ratios described in the composition column of Table 3 were obtained according to the test numbers. Encapsulate and rotate for 20 hours to mix. Next, the obtained mixed powder was filled in a carbon mold and hot-pressed under a vacuum atmosphere at a temperature shown in Table 5 for a holding time of 2 hours and a pressure of 30 MPa to obtain a sintered body. .. Next, the sintered body taken out from the hot press was subjected to hot isostatic pressing at the temperature shown in Table 5. Further, the pressing force was set in the range of 100 to 200 MPa. Further, this was ground using a general-purpose lathe and a surface grinder to obtain a disk-shaped sputtering target having a diameter of 180 mm and a thickness of 5 mm. Table 3 shows the target composition in each test number calculated from the mixing ratio of the raw material powders, and the molar ratio (X) (%) of metallic Co to the total of metallic Co and metallic Pt in the target. Table 3 shows the molar ratio of metallic Co to the total of metallic Co and metallic Pt in the Co—Pt alloy particle phase (equal to the composition of the Co—Pt alloy powder) (Y) (%).

(2. Analysis of target organization)
Each sputtering target obtained by the above procedure was observed by the following procedure, and the average particle diameters of the Co particle phase, the Co—Pt alloy particle phase, the particle phase of the third element, and the phase of the nonmagnetic material were obtained. .. The Co particle phase, the Co-Pt alloy particle phase, the particle phase of the third element, and the phase of the non-magnetic material were identified using the element mapping image of FE-EPMA. The results are shown in Table 4.

(2-1 Co-Pt alloy particle phase)
In the present invention, the average particle size of the Co-Pt alloy particle phase is calculated by the following method. Using a mirror-polished cut surface that is horizontal to the sputtering surface of the sputtering target, two laterally horizontal cutting lines on a SEM photograph of length 70 μm × width 95 μm taken at 3000 times. The photograph is divided into three parts at equal intervals in the vertical direction, the cutting length of the Co—Pt alloy particle phase cut along each cutting line is measured, and the average value (μm) of the cutting length is determined for each visual field. The thickness of the cutting line is 1/400 of the vertical length of the photograph. This is carried out in any 10 visual fields, and the average value of the 10 visual fields is used as the measured value. The Co-Pt alloy particle phase, which is included only partly in the visual field, is excluded from the measurement target.

(2-2 Co particle phase)
In the present invention, the average particle size of the Co particle phase is calculated by the following method. The size of the Co particle phase was measured by using a mirror-polished cut surface of the surface that is horizontal to the sputtering surface of the sputtering target, and on a SEM photograph of 1120 μm in length×1500 μm in width taken at 220 times. The photograph was divided into three parts at equal intervals in the vertical direction by two horizontal cutting lines, and the cutting length of the Co particle phase cut by each cutting line was measured. The average cutting length (μm) ) For each field of view. The thickness of the cutting line is 1/400 of the vertical length of the photograph. This is carried out in any 10 visual fields, and the average value of the 10 visual fields is used as the measured value. Note that the Co particle phase, which is included only partly in the visual field, is excluded from the measurement target.

(2-3 Particle Phase of Third Element)
In the present invention, when the third element forms an independent particle phase, the average particle size of the particle phase of the third element is calculated by the following method. Using a mirror-polished cut surface that is horizontal to the sputtering surface of the sputtering target, two horizontal cutting lines are formed on the SEM photograph of 215 μm in length × 290 μm in width taken at 1000 times. The photograph is divided into three parts at equal intervals in the vertical direction, the cutting length of the particle phase of the third element cut along each cutting line is measured, and the average value (μm) of the cutting length is obtained for each visual field. The thickness of the cutting line is 1/400 of the vertical length of the photograph. This is carried out in any 10 visual fields, and the average value of the 10 visual fields is used as the measured value. The particle phase of the third element, which is included in the visual field only partially, is excluded from the measurement target.

(2-4 Particle phase of non-magnetic material)
In the present invention, the average particle size of the particle phase of the nonmagnetic material is calculated by the following method. Using a mirror-polished cut surface that is horizontal to the sputtering surface of the sputtering target, two laterally horizontal cutting lines on a SEM photograph of 70 μm in length × 95 μm in width taken at 3000 times. The photograph is divided into three parts at equal intervals in the vertical direction, the cutting length of the particle phase of the non-magnetic material cut along each cutting line is measured, and the average value (μm) of the cutting length is determined for each visual field. The thickness of the cutting line is 1/400 of the vertical length of the photograph. This is carried out in any 10 visual fields, and the average value of the 10 visual fields is used as the measured value. The particle phase of the non-magnetic material, which is included in the visual field only partially, is excluded from the measurement target.

(3. Measurement of leakage magnetic flux)
The leakage magnetic flux of each sputtering target obtained by the above procedure was measured according to ASTM F2086-01 (Standard Test Method for Pass Through Flux of Circular Magnetic Sputtering Targets, Method 2). The leakage magnetic flux density (PTF) measured by fixing the center of the target and rotating it at 0°, 30°, 60°, 90° and 120° was divided by the value of the reference field defined in ASTM, and 100 Multiplied by and expressed as a percentage. The results of averaging these 5 points are shown in Table 5 as the average leakage magnetic flux density (PTF (%)).

(4. Particle measurement)
Each of the sputtering targets obtained by the above procedure was attached to a magnetron sputtering device (C-3010 sputtering system manufactured by Canon Anelva) and sputtering was performed. The sputtering conditions were an input power of 1 kW, an Ar gas pressure of 1.7 Pa, a pre-sputtering of 2 kWhr, and a film formation for 20 seconds on a silicon substrate having a diameter of 4 inches. Then, the number of particles having a particle diameter of 0.07 μm or more attached to the substrate was measured by a surface foreign matter inspection device (Candela CS920, manufactured by KLA-Tencor). The results are shown in Table 5.

(5. XRD measurement)
Using the X-ray diffractometer (Ultima IV manufactured by Rigaku Co., Ltd.) under the measurement conditions described above, the cut surface of each sputtering target, which is horizontal to the sputtering surface, obtained by the above procedure is mirror-polished. The measurement was performed. In the XRD measurement, the measurement range of 2θ is set to 30° to 60°, 33.27±2°, 41.52±2°, 47.76±2°, 49.44±2°, and 54.21±. The ratio of the peak intensity at each diffraction angle (2θ) of 2° to the background intensity (average value of the intensity of 2θ=37.0 to 38.0°) was investigated. The results are shown in Table 5. Moreover, the XRD profiles of Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1, Example 2, Example 3, Example 5, and Example 7 are shown in FIGS. 1 to 8, respectively.

Claims (9)

Co:Pt=X:100-X (59≦X<100) at a molar ratio of a metal Co and a metal Pt in a total amount of 70 mol% or more and a metal Cr content of 0 mol% or more and 20 mol% or less. The target,
A Co particle phase containing 90 mol% or more of metallic Co and having an average particle size of 30 to 300 μm,
A Co-Pt alloy containing metallic Co and metallic Pt in a total amount of 70 mol% or more and having an average particle size of 7 μm or less under the condition of Co:Pt=Y:100-Y (20≦Y≦60.5) in a molar ratio. A ferromagnetic material sputtering target having a particle phase. A total of 30 mol% or less of one or more third elements selected from the group consisting of B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Al, Si and Zn. Item 1. The ferromagnetic material sputtering target according to Item 1. The ferromagnetic material sputtering target according to claim 1 or 2, containing 25 mol% or less in total of one or more non-magnetic materials selected from the group consisting of carbon, oxides, nitrides, carbides and carbonitrides. .. In XRD measurement with a measurement range of 2θ of 30° to 60°, 33.27±2°, 41.52±2°, 47.76±2°, 49.44±2°, and 54.21±2. The ferromagnetic material sputtering target according to any one of claims 1 to 3, which has a peak at each position of °. A step of preparing Co powder containing 90 mol% or more of metallic Co and having a median diameter of 30 to 300 μm;
A Co-Pt alloy having a median diameter of 7 μm or less, which contains metallic Co and metallic Pt in a total amount of 70 mol% or more under the condition that Co:Pt=Y:100-Y (20≦Y≦60.5) in a molar ratio. A step of preparing powder,
Co—Pt alloy powder and Co powder are mixed, and the total content of metallic Co and metallic Pt is 70 mol% or more under the condition that the molar ratio is Co:Pt=X:100−X (59≦X<100). A step of obtaining a mixed powder containing metallic Cr of 0 mol% or more and 20 mol% or less,
Baking the mixed powder,
The method for manufacturing a ferromagnetic material sputtering target according to claim 1, further comprising: In the step of obtaining the mixed powder, one or more powders selected from the group consisting of B, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Al, Si and Zn are further mixed. The manufacturing method according to claim 5, further comprising: The step of obtaining the mixed powder further includes mixing one or more non-magnetic materials selected from the group consisting of carbon, oxides, nitrides, carbides and carbonitrides. The manufacturing method described. In the step of preparing a Co—Pt alloy powder having a median diameter of 10 μm or less, a powder obtained by mixing Co powder and Pt powder at a molar ratio of Co:Pt=Y:100-Y (20≦Y≦60.5) is used. In the XRD measurement in which the firing temperature was 800° C. to 1000° C. and the measurement range of 2θ was 30° to 60°, 2θ=33.27±2°, 41.52±2°, 47.76±2° , 49.44±2°, and 54.21±2°, and a step of obtaining a first sintered body having peaks at respective positions and a step of crushing the first sintered body. 7. The manufacturing method according to any one of 7. A method of manufacturing a magnetic recording film, comprising using the sputtering target according to claim 1.

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