TWI608114B - Sputtering target containing Co or Fe - Google Patents

Description

Sputter target containing Co or Fe

The present invention relates to a magnetic material sputtering target used for film formation of a magnetic thin film of a magnetic recording medium (especially a granular film of a magnetic recording medium using a perpendicular magnetic recording type), and A non-magnetic material particle-dispersed magnetic material sputtering target having Co or Fe as a main component, and the sputtering target can suppress abnormal discharge (which is a cause of particles) of the non-magnetic material during sputtering.

A recording layer of a hard disk using a perpendicular magnetic recording method has been using a material having a ferromagnetic metal of Co, Fe, and Ni as a base. Among them, a composite material composed of a ferromagnetic alloy and a non-magnetic inorganic material such as Co-Cr system, Co-Pt system, Co-Cr-Pt system, or Fe-Pt system containing Co or Fe as a main component is often used. Further, since the magnetic film of the magnetic recording medium such as the hard disk has high productivity, it is often produced by sputtering a strong magnetic material sputtering target containing the above material as a component.

As a method of producing such a sputtering target for a magnetic recording medium, a melting method and a powder metallurgy method are considered. Which method is used for the production, because it is based on the required characteristics, it cannot be generalized, but a sputtering target composed of a ferromagnetic alloy and non-magnetic inorganic particles used in a recording layer of a perpendicular magnetic recording type hard disk is generally used. It is made by powder metallurgy. This is because it is necessary to uniformly disperse the inorganic particles in the alloy matrix, so that it is difficult to produce by the melting method.

As a powder metallurgy method, for example, Patent Document 1 proposes a method of mixing Co powder, Cr powder, TiO ₂ powder, and SiO ₂ powder, and then mixing the mixed powder and Co sphere with a planetary motion type mixer. The powder was mixed, and the mixed powder was molded by hot pressing to obtain a sputtering target for a magnetic recording medium.

The target structure in this case is a state in which the spherical phase (B) is present in the metal matrix phase (A) in which the inorganic particles are uniformly dispersed (refer to FIG. 1 of Patent Document 2). Although such a structure is preferable in terms of improving the leakage flux, it cannot be said to be a good sputtering target for a magnetic recording medium from the viewpoint of suppressing generation of particles during sputtering.

Further, Patent Document 2 proposes a method of mixing a Co-Cr binary alloy powder, a Pt powder, and a SiO ₂ powder, and subjecting the obtained mixed powder to hot pressing to obtain a magnetic recording medium film. Sputter target.

Although the target structure in this case is not shown, it is described that the Pt phase, the SiO ₂ phase, and the Co-Cr binary alloy phase are visible, and a diffusion layer can be observed around the Co-Cr binary alloy phase. Such an organization cannot be said to be a good sputtering target for magnetic recording media.

Further, Patent Document 3 proposes a sputtering target comprising a mother phase of Co and Pt and a metal oxide phase having an average particle diameter of 0.05 μm or more and less than 7.0 μm, which is capable of suppressing crystal grain growth and obtaining magnetic permeability. Low and high density targets enhance filming efficiency.

Further, Patent Document 4 discloses that the average particle diameter of the particles forming the oxide phase is 3 μm or less, and Patent Document 5 describes that the ceria particles or the titanium oxide particles are perpendicular to the main surface of the sputtering target. In the case where the particle diameter perpendicular to the main surface of the sputtering target is Dn, and the particle diameter parallel to the main surface is Dp, 2≦Dp/Dn is satisfied.

However, these conditions are not sufficient and are currently requiring further improvement.

Patent Document 1: International Publication No. 2011/089760

Patent Document 2: JP-A-2009-1860

Patent Document 3: Japanese Laid-Open Patent Publication No. 2009-102707

Patent Document 4: Japanese Laid-Open Patent Publication No. 2009-215617

Patent Document 5: Japanese Laid-Open Patent Publication No. 2011-222086

Patent Document 6: Japan's Special Wish 2012-036562

In general, a non-magnetic material particle-dispersed ferromagnetic material sputtering target containing Co or Fe as a main component is an insulator because the non-magnetic material such as SiO ₂ , Cr ₂ O ₃ or TiO _{2 is} contained as an insulator. The cause of the discharge. Moreover, this abnormal discharge causes the problem of particles generated during the sputtering process.

The present invention has been made in view of the above problems, and it is an object of the invention to maintain high PTF while suppressing abnormal discharge of the non-magnetic material and to reduce generation of particles during sputtering by abnormal discharge. Although the probability of abnormal discharge can be reduced by reducing the particle size of the non-magnetic material particles up to now, as the recording density of the magnetic recording medium increases, the degree of allowable particles becomes stricter, and therefore the object is to provide a further improvement. An improved non-magnetic material particle-dispersed ferromagnetic material sputtering target is obtained.

In order to solve the problem, the inventors of the present invention have found that by adjusting the structure of the target (non-magnetic material particles), abnormal discharge due to non-magnetic materials during sputtering does not occur, and it is possible to obtain less particles. The target.

Based on this finding, the present invention provides the following invention.

1) A sputtering target which is a sintered sputtering target composed of a material in which non-magnetic material particles are dispersed in a magnetic material containing Co or Fe, and is characterized in that the structure observed on the polished surface of the target is It is composed of non-magnetic material particles having an average particle diameter of 1.8 μm or less, a metal phase containing Co or Fe in which the non-magnetic material particles are dispersed, and metal particles, and is located at a distance of any two points on the outer edge of the non-magnetic material particles. The maximum value is the maximum diameter. When the minimum value of the distance between the two straight lines is the minimum diameter when the particles are held in parallel with two straight lines, the non-magnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less are occupied. 60% or more of the non-magnetic material particles in the microstructure observed in the polished surface of the target, and the maximum diameter of the distance between any two points on the outer edge of the metal particle is the maximum diameter, and two straight lines in parallel When the minimum value of the distance between the two straight lines is the minimum diameter when the metal particles are sandwiched, the metal particles having a maximum diameter and a minimum diameter of 30 μm or more have an average of one or more in a field of view of 1 mm ² .

(2) The sputtering target according to the above 1), wherein the non-magnetic material particles are selected from the group consisting of B ₂ O ₃ , CoO, Co ₃ O ₄ , MnO, Mn ₃ O ₄ , SiO ₂ , SnO ₂ , TiO ₂ , Ti One or more oxides of ₂ O ₃ , Cr ₂ O ₃ , Ta ₂ O ₅ , WO ₂ , WO ₃ , and ZrO ₂ , and the content thereof is 0.5 to 20 mol%.

(3) The sputtering target according to the above 1) or 2), wherein Cr is 0 mol% or more and 15 mol% or less, Pt is 5 mol% or more and 30 mol% or less, excluding a nonmagnetic material, and the remainder is Co and an unavoidable impurity. .

(4) The sputtering target according to the above 3), which further contains 0.5 mol% or more and 12 mol% or less of at least one selected from the group consisting of Mg, Al, Si, Mn, Nb, Mo, Ru, Pd, Ta, W, and B. element.

The sputtering target according to any one of the above 1 to 4, wherein the metal particles are composed of Co or Fe.

By the non-magnetic material particle-dispersed magnetic material sputtering target of the present invention adjusted in this manner, the following target can be obtained: maintaining high PTF without abnormal discharge caused by non-magnetic material during sputtering, and particle generation less. Thereby, there is an excellent effect that an effect of improving the cost by improving the yield can be obtained.

Fig. 1 is a view (photograph) showing the target structure of Co-Pt-Cr-SiO ₂ -TiO ₂ -Cr ₂ O _{3 of} Example 1.

Fig. 2 is a view showing a structure in which non-magnetic material particles of the target of Example 1 are dispersed in a metal phase (an enlarged photograph of Fig. 1).

Fig. 3 is a view showing the image analysis processing (binarization processing) of Fig. 2 in order to make the non-magnetic material particles clear.

Fig. 4 is a view (photograph) showing the target structure of Co-Pt-Ru-Ta-SiO ₂ -TiO ₂ -CoO-B ₂ O _{3 of} Example 2.

Fig. 5 is a view showing a structure in which non-magnetic material particles of the target of Example 2 are dispersed in a metal phase (an enlarged photograph of Fig. 4).

The sputtering target of the present invention is a sintered sputtering target in which a non-magnetic material particle is dispersed in a material containing Co or Fe, and the structure observed on the polished surface of the target is an average particle diameter. Non-magnetic material particles of 1.8 μm or less and dispersed with the aforementioned non-magnetic material particles It is composed of a metal phase containing Co or Fe and metal particles. By making the size of the non-magnetic material particles to have an average particle diameter of 1.8 μm or less, generation of particles can be suppressed.

The inventors of the present invention have previously found that the shape of the non-magnetic material particles is preferably spherical, and the shape of the non-magnetic material particles is at least close to a spherical shape, which is an effective means for preventing generation of particles (Patent Document 6). .

That is, in order to improve the magnetic properties, it is necessary to have a certain amount of oxide (non-magnetic material), but if it is a different shape, a place where an oxide exists in a certain area of the target surface and a place where no oxide exists The distribution will make a difference and become prone to segregation. It has been found that if the particles are spherical or close to the oxide particles of the sphere, since the particle shape is uniform, segregation is reduced, and generation of particles can be effectively suppressed.

According to the above findings, the maximum value of the distance between any two points on the outer edge of the non-magnetic material particles observed on the polished surface of the target is the maximum diameter, and the two straight lines are held by the two parallel lines. When the minimum value of the distance between the two is the minimum diameter, the difference between the maximum diameter and the minimum diameter is 0.7 μm or less.

Further, such non-magnetic material particles preferably occupy most of the target, i.e., preferably 60% or more, preferably 90% or more, more preferably 100%. Thereby, the generation of particles can be greatly suppressed.

Further, since the present invention has found new insights from the above findings, not only the form of the non-magnetic material particles but also the form of the metal particles containing Co or Fe is specified, whereby abnormal discharge can be suppressed, and generation of particles can be further suppressed.

That is, the maximum value of the distance between any two points on the outer edge of the metal particle observed on the polished surface located in the target is the maximum diameter, and the two straight lines are used to sandwich the particle. When the minimum value of the distance is the minimum diameter, the metal particles having a maximum diameter to the minimum diameter of 30 μm or more have an average of one or more in a field of view of 1 mm ² , and preferably have an average of three or more. There are more than 5 on average.

Further, in the present invention, any five sites in the target surface are observed with a microscope, and the number of metal particles having a maximum diameter to a minimum diameter of 30 μm or more in a field of view of 1 mm ^{2 is} counted, and the average number is obtained from the total.

When the maximum value of the distance between any two points on the outer edge of the metal particle is the maximum diameter, and the minimum value of the distance between the two lines is the minimum diameter when the metal particles are held by two parallel lines, if it is the largest When the sum of the diameter and the minimum diameter is 30 μm or more, and there is an average of one or more in the field of view of 1 mm ² , the leakage magnetic flux becomes large. Therefore, in the use of the magnetron sputtering apparatus, the ionization of the inert gas can be efficiently promoted to obtain a stable discharge.

On the other hand, when the maximum value of the distance between any two points on the outer edge of the metal particle is the maximum diameter, and the minimum value of the distance between the two straight lines is the minimum diameter when the metal particles are held by two straight lines in parallel When the sum of the largest diameter and the minimum diameter is less than 30 μm, or when the metal particles of 30 μm or more have an average of less than one in the field of 1 mm ² , the above effects are hardly obtained.

In addition, when the sum of the maximum diameter and the minimum diameter is 50 μm or more, the above effect is further enhanced. However, when the sum of the maximum diameter and the minimum diameter exceeds 300 μm, the distribution of oxide particles may be uneven.

The ferromagnetic material sputtering target of the present invention is particularly effective for a Fe-based alloy such as a Co-Cr alloy, a Co-Pt-based alloy, a Co-Cr-Pt-based alloy, or a Fe-based alloy such as a Fe-Pt-based alloy, but The present invention can be applied to a well-known ferromagnetic material, and the blending ratio of the components required as a magnetic recording medium can be appropriately adjusted depending on the purpose.

As a Co-based alloy, Cr can be made 0 mol% or more and 15 mol% or less, and Pt is 5 mol%. The above 30 mol% or less does not include a non-magnetic material, and the remainder is a sputtering target composed of Co and unavoidable impurities. As the Fe-based alloy, a sputtering target in which Pt exceeds 0 mol% and is 60 mol% or less, does not include a non-magnetic material, and the remainder is composed of Fe and unavoidable impurities can be obtained.

The composition of these components is merely a preferred range of values for the purpose of utilizing the properties as a ferromagnetic material, and of course other values are applicable.

The non-magnetic material added to the above ferromagnetic material is selected from the group consisting of B ₂ O ₃ , CoO, Co ₃ O ₄ , MnO, Mn ₂ O ₃ , SiO ₂ , TiO ₂ , Ti ₂ O ₃ , Cr ₂ O ₃ , Ta _{2 .} One or more oxides of O ₅ , WO ₂ , WO ₃ , and ZrO ₂ are usually contained in the target in an amount of 0.5 to 20 mol%. These oxides can be arbitrarily selected depending on the type of ferromagnetic film required. The above added amount is an effective amount for exerting an additive effect.

Further, in the sputtering target of the present invention, 0.5 to 12 mol% of one or more elements selected from the group consisting of Mg, Al, Si, Mn, Nb, Mo, Ru, Pd, Ta, W, and B may be added. These are elements that are added as needed in order to enhance the characteristics of the magnetic recording medium. The amount of addition described above is an effective amount for exerting an effect of addition.

Further, the sputtering target structure of the present invention is composed of non-magnetic material particles, a metal phase containing Co or Fe in which non-magnetic material particles are dispersed, and metal particles, and the metal particles are preferably composed of Co or Fe.

The maximum magnetic permeability of the metal particles is higher than a metal matrix having different compositions (a metal phase in which non-magnetic material particles are dispersed), and a structure in which each metal particle is separated by a surrounding structure composed of a metal matrix. The reason why the leakage magnetic field is improved in the target of such a structure is not necessarily clear at present, but it is considered that the reason is that the magnetic flux inside the target generates a denser portion and a more sparse portion, and has a uniform magnetic permeability. Compared with the tissue, since the magnetostatic energy becomes higher, the magnetic flux leaks to the outside of the target. It is more advantageous in quantity.

The sputtering target of the present invention can be produced by powder metallurgy. In the case of the powder metallurgy method, the metal coarse powder described later is not included, and the metal raw material powder such as Co, Cr, Pt, Fe, etc., and the non-magnetic raw material powder such as SiO ₂ are prepared, and the metal powder such as Ru is added as needed. . The particle size of the raw material is preferably such that the average particle diameter is 10 μm or less and the non-magnetic material powder is 5 μm or less. The non-magnetic material raw material powder is as close as possible to a spherical shape, and it is easier to achieve the fine structure of the present invention. Further, alloy powders of these metals may be prepared in place of the powder of each metal element. Alternatively, the particle size of the powder can be measured using a laser diffraction particle size distribution meter (HORIBA LA-920).

Then, these metal powders and alloy powders are weighed into a desired composition, and mixed and pulverized by a known method such as a ball mill. In order to shorten the mixing time and improve productivity, it is preferred to use a high energy ball mill. Here, as for the metal raw material powder, a metal coarse powder of at least one component is preferably mixed in a small amount, and the particle diameter of the metal coarse powder is in the range of 50 μm or more and 300 μm or less. At this time, in order to maintain the particle diameter, it is preferable to carry out the addition after mixing for a long time using a ball mill, or to mix using a mixer which is not pulverizing and mild, such as a mixer. Alternatively, it may be added during the mixing of the ball mill to perform ball milling for a short period of time. Thereby, the metal particles become flat, and the difference between the long diameter and the short diameter becomes large.

Although the metal particles may be spherical or flat (sheet-like) in the above manner, the spherical or flat metal particles have advantages and disadvantages of the respective shapes. The choice of the shape should be selected according to the purpose of use of the target.

Specifically, when the target material is produced by the sintering method, the spherical shape is less likely to generate voids at the interface between the metal matrix (A) and the phase (B), and the density of the target can be increased. Moreover, in the same volume, since the spherical surface area is small, when the target raw material is sintered, the metal substrate (A) and the phase (B) are Metal elements are less likely to diffuse. In addition, the spherical shape herein refers to a three-dimensional shape including a sphere, a quasi-spherical sphere, a flat sphere (rotating ellipsoid), and a pseudo-ball. Both refer to the difference between the long axis and the short axis of 0 to 50%.

On the other hand, when the metal particles are flat, as the effect of the wedge, there is an effect of preventing the metal particles from being detached from the surrounding metal substrate (A) during sputtering. Further, by destroying the spherical shape, the unevenness of the sputtering speed which is likely to occur in the spherical shape can be alleviated, and the occurrence of particles due to the boundary at which the sputtering speed is different can be suppressed.

In the present invention, it is important that, as described earlier, the maximum value of the distance between any two points on the outer edge of the non-magnetic material particles in the tissue observed by the abrasive surface located in the target is the maximum diameter, in parallel. When the minimum value of the distance between two straight lines is the minimum diameter when the two particles are held by two straight lines, the difference between the maximum diameter and the minimum diameter is 0.7 μm or less.

Further, in the present invention, it is particularly important that the maximum value of the distance between any two points on the outer edge of the metal particle observed by the polished surface located in the target is the maximum diameter, and the metal is held in parallel with two straight lines. When the minimum value of the distance between the straight lines in the grain 2 is the minimum diameter, the metal particles having a maximum diameter and a minimum diameter of 30 mm or more have an average of one or more in a field of view of 1 mm ² .

The calculation of the maximum diameter and the minimum diameter is performed by projecting a microscope image of the polished surface in the target to the PC and using the image processing analysis software. The image analysis processing software system uses the shape analysis software (VK-Analyzer VK-H1A1) manufactured by KEYENCE.

The mixed powder obtained in the above manner is sintered using hot pressing or hot hydrostatic pressure. In addition, depending on the composition of the target, the conditions for the non-magnetic material particles to be spherical and the conditions for the metal particles to be flat are found by setting the mixing conditions and sintering conditions of the above-mentioned raw materials, and if the manufacturing conditions are fixed, This kind of non-magnetic material particles and metal particles can be obtained all the time. Sintered body target.

Example

Hereinafter, description will be given based on examples and comparative examples. In addition, this embodiment is only an example and is not limited by this illustration. That is, the present invention is only limited by the scope of the claims, and includes various modifications other than the embodiments included in the present invention.

(Example 1)

Co powder having an average particle diameter of 4 μm, Cr powder having an average particle diameter of 5 μm, and Pt powder having an average particle diameter of 3 μm were prepared as a metal raw material powder, and TiO ₂ powder having an average particle diameter of 1.2 μm and spherical SiO _{2 having} an average particle diameter of 0.7 μm were prepared. A powder, a Cr ₂ O ₃ powder having an average particle diameter of 1 μm was used as the non-magnetic material powder. Further, a Co coarse powder having a particle diameter adjusted to a range of 50 μm or more and 150 μm or less was prepared, and the ratio of the Co powder having an average particle diameter of 4 μm to the Co coarse powder was 7:3 by weight. 2000 g of these powders were weighed in the following composition ratio.

Composition: 69Co-18Pt-2Cr-5SiO ₂ -2TiO ₂ -4Cr ₂ O ₃ (mol%)

Next, in addition to the Co coarse powder, the weighed powder was sealed with a tungsten alloy grinding ball of a pulverizing medium in a ball mill pot having a capacity of 10 liters, and rotated for 120 hours to be mixed. Then, the Co coarse powder was placed in a ball mill and mixed for 1 hour. The mixed powder obtained in this manner was filled in a carbon mold, and hot pressed at a temperature of 1,100 ° C, a holding time of 2 hours, and a pressing force of 30 MPa in a vacuum atmosphere to obtain a sintered body. Further, the sintered body was cut by a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

The average leakage flux density of the target produced in this manner was measured and found to be 30%. In addition, the measurement of the leakage flux is carried out in accordance with ASTM F2086-01 (Standard Test Method for Pass Through Flux of Circular Magnetic Sputtering Targets, Method 2). specific In the case of fixing the center of the target, the leakage flux density measured by rotating 0 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees is divided by the value of the reference field defined by ASTM, multiplied by 100, in percentage Said. Then, the result of the five-point average is used as the average leakage magnetic flux density (%).

The surface of the target was polished, and the structure was observed with a microscope. As a result, as shown in Fig. 1, it was found that metal particles were dispersed in the structure in which the non-magnetic material particles were dispersed in the metal phase. When the maximum value of the distance between any two points on the outer edge of the metal particle is the maximum diameter, and the minimum value of the distance between the two straight lines is the minimum diameter when the metal particles are held by two parallel lines, the maximum is The metal particles having a sum of the diameter and the minimum diameter of 30 μm or more have an average of 40 in the field of 1 mm ² .

2 is an enlarged view of FIG. 1 for observing non-magnetic material particles. When the maximum value of the distance between any two points on the outer edge of the non-magnetic material particle is the maximum diameter, and the minimum value of the distance between the two lines is the minimum diameter when the metal particles are sandwiched by two parallel lines, The oxide particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less have 85% in the microscope field and an average particle diameter of 0.75 μm.

When the maximum diameter, the minimum diameter, and the average particle diameter of the oxide particles are calculated, as shown in FIG. 3, a microscope image is projected onto a PC screen, and image analysis processing (binarization processing) is performed to form oxide particles ( After the outline of the black part is clear, calculate this.

Next, the target was mounted on a DC magnetron sputtering apparatus for sputtering. The sputtering conditions were a sputtering power of 1.2 kW and an Ar gas pressure of 1.5 Pa, and after pre-sputtering of 2 kWhr, the target film thickness was 1000 nm, and sputtering was performed on a substrate having a diameter of 4 Å. Then, the number of particles attached to the substrate was measured with a particle counter. At this time, the number of particles on the substrate was four.

In addition, even in the case of no sputtering, if the measurement is performed by the particle counter, the number of particles of 0 to 5 is sometimes counted on the substrate, so the number of four particles in the embodiment can be said to be extremely small. The extent of it.

(Example 2)

Co powder having an average particle diameter of 4 μm, Pt powder having an average particle diameter of 3 μm, Ru powder having an average particle diameter of 7 μm, and Ta powder having an average particle diameter of 6 μm were prepared as metal raw material powder, and TiO ₂ powder having an average particle diameter of 1.2 μm was prepared and averaged. A spherical SiO ₂ powder having a particle diameter of 0.7 μm, a CoO powder having an average particle diameter of 0.8 μm, and a B ₂ O ₃ powder having an average particle diameter of 5 μm were used as the oxide powder. Further, a Co coarse powder having a particle diameter adjusted to a range of 50 μm to 300 μm was prepared, and the ratio of the Co powder having an average particle diameter of 4 μm to the Co coarse powder was 7:3 by weight. 2000 g of these powders were weighed in the following composition ratio.

Composition: 61.2Co-22Pt-3Ru-0.8Ta-6SiO ₂ -2TiO ₂ -4CoO-1B ₂ O ₃ (mol%)

Next, in addition to the Co coarse powder, the weighed powder was sealed with a tungsten alloy grinding ball of a pulverizing medium in a ball mill having a capacity of 10 liters, and rotated for 120 hours to be mixed. Then, the Co coarse powder was placed in a ball mill and mixed for 1 hour. The mixed powder obtained in this manner was filled in a carbon mold, and hot pressed in a vacuum atmosphere under the conditions of a temperature of 1000 ° C, a holding time of 2 hours, and a pressing force of 30 MPa to obtain a sintered body. Further, the sintered body was cut by a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

The target of Example 2 had an average leakage flux density of 28%. The surface of the target was polished, and the structure was observed under a microscope. As a result, as shown in Fig. 4, it was found that metal particles were dispersed in the structure in which the non-magnetic material particles were dispersed in the metal phase. The metal particles having a maximum diameter and a minimum diameter of 30 μm or more which were evaluated in the same manner as in Example 1 were confirmed to have an average of 19 metal particles in a field of 1 mm ² . In addition, FIG. 5 is an enlarged view of FIG. 4 in order to observe the non-magnetic material particles. The ratio of the non-magnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less, which was evaluated in the same manner as in Example 1, was 64%, and the average particle diameter was 1.26 μm.

Next, the target was mounted on a DC magnetron sputtering apparatus for sputtering. The sputtering conditions were the same as in Example 1. The sputtering power was 1.2 kW, the Ar gas pressure was 1.5 Pa, and after 2 kWhr of pre-sputtering, the target film thickness was 1000 nm, and sputtering was performed on a 4 吋 diameter substrate. Then, the number of particles attached to the substrate was measured with a particle counter. At this time, the number of particles on the substrate was four.

(Example 3)

Co powder having an average particle diameter of 4 μm, Pt powder having an average particle diameter of 3 μm, and Co-B powder having an average particle diameter of 7 μm were prepared as a metal raw material powder, and TiO ₂ powder having an average particle diameter of 1.2 μm and a spherical body having an average particle diameter of 0.7 μm were prepared. SiO ₂ powder, MnO powder having an average particle diameter of 0.8 μm, and Co ₃ O ₄ powder having an average particle diameter of 2 μm were used as the oxide powder. Further, a Co coarse powder having a particle diameter adjusted to a range of 50 μm to 300 μm was prepared, and the ratio of the Co powder having an average particle diameter of 4 μm to the Co coarse powder was 7:3 by weight. 2000 g of these powders were weighed in the following composition ratio.

Composition: 63Co-21Pt-3B-6SiO ₂ -2TiO ₂ -4MnO-1Co ₃ O ₄ (mol%)

Next, in addition to the Co coarse powder, the weighed powder was sealed with a tungsten alloy grinding ball of a pulverizing medium in a ball mill having a capacity of 10 liters, and rotated for 120 hours to be mixed. Then, the Co coarse powder was placed in a ball mill and mixed for 1 hour. The mixed powder obtained in this manner was filled in a carbon mold, and hot pressed in a vacuum atmosphere under the conditions of a temperature of 1000 ° C, a holding time of 2 hours, and a pressing force of 30 MPa to obtain a sintered body. Further, the sintered body was cut by a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

The target of Example 3 had an average leakage flux density of 31%. When the surface of the target was polished and the structure was observed with a microscope, it was found that metal particles were dispersed in the structure in which the non-magnetic material particles were dispersed in the metal phase. The metal particles having a maximum diameter to a minimum diameter of 30 μm or more which were evaluated in the same manner as in Example 1 were confirmed to have an average of 18 metal particles in a field of 1 mm ² . Further, the percentage of the non-magnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less, which was evaluated in the same manner as in Example 1, was 60%, and the average particle diameter was 1.16 μm.

Next, the target was mounted on a DC magnetron sputtering apparatus for sputtering. The sputtering conditions were the same as in Example 1. The sputtering power was 1.2 kW, the Ar gas pressure was 1.5 Pa, and after 2 kWhr of pre-sputtering, the target film thickness was 1000 nm, and sputtering was performed on a 4 吋 diameter substrate. Then, the number of particles attached to the substrate was measured with a particle counter. At this time, the number of particles on the substrate was five.

(Example 4)

Fe powder having an average particle diameter of 4 μm, Pt powder having an average particle diameter of 3 μm, and Fe—B powder having an average particle diameter of 7 μm were prepared as a metal raw material powder, and spherical SiO ₂ powder having an average particle diameter of 0.8 μm was prepared as an oxide powder. Further, Fe coarse powder having a particle diameter adjusted to a range of 50 μm to 300 μm was prepared, and the ratio of the Fe powder having an average particle diameter of 4 μm to the above-mentioned Fe coarse powder was 8:2 by weight. 2000 g of these powders were weighed in the following composition ratio.

Composition: 52Fe-25Pt-5B-18SiO ₂ (mol%)

Next, in addition to the Fe coarse powder, the weighed powder was sealed with a tungsten alloy grinding ball of a pulverizing medium in a ball mill having a capacity of 10 liters, and rotated for 120 hours to be mixed. Then, the Fe coarse powder was placed in a ball mill and mixed for 1 hour. The mixed powder obtained in this manner was filled in a carbon mold, and hot pressed in a vacuum atmosphere under the conditions of a temperature of 1300 ° C, a holding time of 2 hours, and a pressing force of 30 MPa to obtain a sintered body. Further, the sintered body was cut by a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

The target of Example 4 had an average leakage flux density of 61%. When the surface of the target was polished and the structure was observed with a microscope, it was found that metal particles were dispersed in the structure in which the non-magnetic material particles were dispersed in the metal phase. The metal particles having a maximum diameter to a minimum diameter of 30 μm or more which were evaluated in the same manner as in Example 1 were confirmed to have an average of four metal particles in a field of 1 mm ² . The percentage of the nonmagnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less, which was evaluated in the same manner as in Example 1, was 65%, and the average particle diameter was 1.29 μm.

Next, the target was mounted on a DC magnetron sputtering apparatus for sputtering. The sputtering conditions were the same as in Example 1. The sputtering power was 1.2 kW, the Ar gas pressure was 1.5 Pa, and after 2 kWhr of pre-sputtering, the target film thickness was 1000 nm, and sputtering was performed on a 4 吋 diameter substrate. Then, the number of particles attached to the substrate was measured with a particle counter. At this time, the number of particles on the substrate was six.

(Comparative Example 1)

Co powder having an average particle diameter of 4 μm, Cr powder having an average particle diameter of 5 μm, and Pt powder having an average particle diameter of 3 μm were prepared as a metal raw material powder, and TiO ₂ powder having an average particle diameter of 1.2 μm and core SiO having an average particle diameter of 0.7 μm were prepared. ₂ powder, Cr ₂ O ₃ powder having an average particle diameter of 1 μm as an oxide powder. Then, 2000 g of these powders were weighed in the following composition ratio.

Composition: 69Co-18Pt-2Cr-5SiO ₂ -2TiO ₂ -4Cr ₂ O ₃ (mol%)

Next, the weighed powder was enclosed in a ball mill having a capacity of 10 liters together with a tungsten alloy grinding ball of a pulverizing medium, and rotated for 120 hours for mixing. The mixed powder obtained in this manner was filled in a carbon mold, and in the same manner as in Example 1, a sintered body was obtained by hot pressing under the conditions of a temperature of 1,100 ° C, a holding time of 2 hours, and a pressing force of 30 MPa. . Further, the sintered body was cut by a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

The target of Comparative Example 1 had an average leakage flux density of 18%. When the surface of the target was polished and the structure was observed with a microscope, the metal particles having a maximum diameter to the minimum diameter of 30 μm or more, which were evaluated in the same manner as in Example 1, had an average of less than one in a field of 1 mm ² . Further, the percentage of the non-magnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less as evaluated in the same manner as in Example 1 was 89%, and the average particle diameter was 0.71 μm.

Next, the target was mounted on a DC magnetron sputtering apparatus for sputtering. The sputtering conditions were the same as in the first embodiment, the sputtering power was 1.2 kW, and the Ar gas pressure was 1.5 Pa. However, since stable discharge could not be obtained, the sputtering power was 1.7 kW, and the Ar gas pressure was 2.8 Pa, and the discharge was stabilized. After pre-sputtering of 2 kWhr, a target film thickness of 1000 nm was sputtered onto a 4 吋 diameter substrate. Then, the number of particles attached to the substrate was measured with a particle counter. At this time, the number of particles on the substrate was nine.

(Comparative Example 2)

Co powder having an average particle diameter of 4 μm, Cr powder having an average particle diameter of 5 μm, and Pt powder having an average particle diameter of 3 μm were prepared as a metal raw material powder, and TiO ₂ powder having an average particle diameter of 1.2 μm and core SiO having an average particle diameter of 0.7 μm were prepared. ₂ powder, Cr ₂ O ₃ powder having an average particle diameter of 1 μm as an oxide powder. Further, a Co coarse powder having a particle diameter adjusted to a range of 50 μm to 300 μm was prepared, and the ratio of the Co powder having an average particle diameter of 4 μm to the Co coarse powder was 7:3 by weight. 2000 g of these powders were weighed in the following composition ratio.

Composition: 69Co-18Pt-2Cr-5SiO ₂ -2TiO ₂ -4Cr ₂ O ₃ (mol%)

Next, in addition to the Co coarse powder, the weighed powder was sealed with a tungsten alloy grinding ball of a pulverizing medium in a ball mill having a capacity of 10 liters, and rotated for 70 hours to be mixed. Then, the Co coarse powder was placed in a ball mill and mixed for 1 hour. The mixed powder prepared in this manner is filled in a carbon mold, and in a vacuum environment, at a temperature of 1100 ° C, a holding time of 2 hours, a pressure of 30 MPa Under the conditions, hot pressing was performed to obtain a sintered body. Further, the sintered body was cut by a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

The target of Comparative Example 2 had an average leakage flux density of 29%. When the surface of the target was polished and the structure was observed with a microscope, the metal particles having a maximum diameter and a minimum diameter of 30 μm or more were evaluated in the same manner as in Example 1, and an average of 36 were observed in a field of 1 mm ² . Further, the ratio of the non-magnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less, which was evaluated in the same manner as in Example 1, was 54%, and the average particle diameter was 1.87 μm.

Next, the target was mounted on a DC magnetron sputtering apparatus for sputtering. The sputtering conditions were the same as in Example 1. The sputtering power was 1.2 kW, the Ar gas pressure was 1.5 Pa, and after 2 kWhr of pre-sputtering, the target film thickness was 1000 nm, and sputtering was performed on a 4 吋 diameter substrate. Then, the number of particles attached to the substrate was measured with a particle counter. At this time, the number of particles on the substrate is as high as 28.

According to the present invention, by adjusting the structure of the sputtering target (especially the shape of the non-magnetic material particles and the metal particles), the leakage magnetic field during sputtering is suppressed, and the abnormal discharge caused by the non-magnetic material is suppressed, so that the present invention is used. The target can be stably discharged when sputtered by a magnetron sputtering device. Moreover, it has the following excellent effects: it can suppress the abnormal discharge of the non-magnetic material, reduce the generation of particles during the sputtering process due to abnormal discharge, and can improve the cost by improving the yield, so it is suitable as a magnetic body for a magnetic recording medium. A strong magnetic material sputtering target used for film formation of a film (especially a hard disk drive recording layer).

Claims (7)

A sputtering target is a sintered body sputtering target composed of a material in which non-magnetic material particles are dispersed in a magnetic material containing Co or Fe, and is characterized in that the structure observed on the polished surface of the target is The non-magnetic material particles having an average particle diameter of 1.8 μm or less and the metal phase and metal particles containing Co or Fe in which the non-magnetic material particles are dispersed are formed, and the maximum value at a distance of any two points on the outer edge of the non-magnetic material particles is In the maximum diameter, when the minimum value of the distance between the two straight lines is the minimum diameter when the particles are sandwiched by two parallel lines, the non-magnetic material particles having a difference between the maximum diameter and the minimum diameter of 0.7 μm or less account for the target. 60% or more of the non-magnetic material particles in the microstructure observed on the polished surface, and the maximum diameter of the distance between any two points on the outer edge of the metal particle is the maximum diameter, and the two straight lines are held in parallel In the case of the metal particles, when the minimum value of the distance between the straight lines is the minimum diameter, the metal particles having a maximum diameter to the minimum diameter of 30 μm or more have an average of one or more in the field of 1 mm ² . The sputtering target of claim 1, wherein the non-magnetic material particles are selected from the group consisting of B ₂ O ₃ , CoO, Co ₃ O ₄ , MnO, Mn ₃ O ₄ , SiO ₂ , SnO ₂ , TiO ₂ , Ti One or more oxides of ₂ O ₃ , Cr ₂ O ₃ , Ta ₂ O ₅ , WO ₂ , WO ₃ , and ZrO ₂ , and the content thereof is 0.5 to 20 mol%. The sputtering target according to the first aspect of the invention, wherein Cr is 0 mol% or more and 15 mol% or less, Pt is 5 mol% or more and 30 mol% or less, excluding a nonmagnetic material, and the remainder is Co and an unavoidable impurity. The sputtering target according to claim 2, wherein Cr is 0 mol% or more and 15 mol% or less, Pt is 5 mol% or more and 30 mol% or less, excluding a nonmagnetic material, and the remainder is Co and unavoidable impurities. For example, the sputtering target of the third application patent scope further contains 0.5 mol% or more and 12 mol. One or more of elements selected from the group consisting of Mg, Al, Si, Mn, Nb, Mo, Ru, Pd, Ta, W, and B. The sputtering target according to claim 4, further comprising 0.5 mol% or more and 12 mol% or less of one or more selected from the group consisting of Mg, Al, Si, Mn, Nb, Mo, Ru, Pd, Ta, W, and B. element. The sputtering target according to any one of claims 1 to 6, wherein the metal particles are composed of Co or Fe.