CN109844167B

CN109844167B - Magnetic material sputtering target and method for producing same

Info

Publication number: CN109844167B
Application number: CN201780063272.8A
Authority: CN
Inventors: 古谷祐树
Original assignee: JX Nippon Mining and Metals Corp
Current assignee: JX Nippon Mining and Metals Corp
Priority date: 2016-12-28
Filing date: 2017-12-07
Publication date: 2022-01-04
Anticipated expiration: 2037-12-07
Also published as: TWI753073B; JPWO2018123500A1; WO2018123500A1; CN109844167A; JP6734399B2; SG11201903240PA; MY191374A; TW201835361A

Abstract

A magnetic material sputtering target comprising oxides with a melting point of 500° C. or lower, characterized in that the average number density of oxides with a particle size of 10 μm or more in the sputtering surface of the sputtering target is 5 /mm ² or less. An object of the present invention is to provide a sputtering target capable of effectively reducing the generation of abnormal discharge and particles caused by oxides in the sputtering target, particularly coarsely grown oxides, and a method for producing the same. .

Description

Magnetic material sputtering target and method for producing same

Technical Field

The present invention relates to a magnetic material sputtering target suitable for forming a magnetic thin film used for a recording layer of a magnetic recording medium or the like, for example, a granular film of a magnetic recording medium of a hard disk adopting a perpendicular magnetic recording system, and particularly relates to a magnetic material sputtering target capable of suppressing abnormal discharge during sputtering and preventing generation of particles, and a method for producing the same.

Background

In a magnetic recording medium such as a hard disk, a magnetic recording layer is formed by making a magnetic material into a thin film on a substrate such as glass, and a magnetron sputtering method using a Direct Current (DC) power supply is widely used for forming the magnetic recording layer in view of high productivity. The magnetron sputtering method comprises the following steps: by disposing the magnet on the rear surface of the target and leaking magnetic flux to the surface of the target, the magnetic flux can confine charged particles in the discharge plasma by the lorentz force, and high-density plasma can be concentrated in the vicinity of the surface of the target, thereby increasing the film formation speed.

In the field of magnetic recording represented by hard disk drives, materials based on Co, Fe, or Ni, which are ferromagnetic metals, are used as materials for forming a magnetic thin film of a magnetic recording layer responsible for recording. For example, in a recording layer of a hard disk adopting an in-plane magnetic recording method in which the magnetization direction of a magnetic material is set to a direction parallel to a recording surface, a Co — Cr-based or Co — Cr — Pt-based ferromagnetic alloy containing Co as a main component has been conventionally used.

On the other hand, a perpendicular magnetic recording system has been put into practical use in which the magnetic recording amount per recording area is increased by setting the magnetization direction of the magnetic material to a direction perpendicular to the recording surface, and has become the mainstream in recent years. In the magnetic recording layer of a hard disk using this perpendicular magnetic recording system, a composite material containing a Co — Cr — Pt-based ferromagnetic alloy containing Co as a main component and a nonmagnetic inorganic substance is often used. In addition, from the viewpoint of high productivity, a magnetic thin film of a magnetic recording medium such as a hard disk is often produced by sputtering using a magnetic material sputtering target containing the above-described material as a component.

As a method for producing such a magnetic material sputtering target, a melting method and a powder metallurgy method are considered. The method by which the sputtering target is manufactured depends on the sputtering characteristics and the film properties required, and thus cannot be generally described. However, the sputtering target used for the recording layer of the perpendicular magnetic recording hard disk which has become the mainstream in recent years is generally produced by a powder metallurgy method. This is because the sputtering target for forming the recording layer of the perpendicular magnetic recording system needs to have inorganic particles uniformly dispersed in an alloy matrix, and it is difficult to realize such a structure by a melting method.

Heretofore, as for the production of a magnetic material sputtering target by a powder metallurgy method, a method for improving the same from several viewpoints has been attempted. For example, patent documents 1 and 2 disclose a sintered sputtering target in which oxide particles are dispersed in an alloy matrix by a powder metallurgy method, and describe that by making an alloy of a specific element composition exist in the alloy matrix as coarse particles, the permeability of the entire target can be reduced, the magnetic Flux (PTF) passing Through the sputtering surface of a magnetic target can be increased, and the plasma density in the vicinity of the sputtering surface can be increased, thereby improving the film formation rate.

As a method from another viewpoint, patent documents 3 and 4 disclose sintered sputtering targets obtained by dispersing oxide particles in an alloy matrix by a powder metallurgy method and sintering the particles, and also disclose techniques for obtaining a fine and uniform texture structure by controlling the shape and dispersion form of the oxide dispersed in the target. In these targets, since the oxide as a dispersion is an insulator, it may cause abnormal discharge depending on the shape and dispersion form thereof, and thus the generation of particles is prevented by suppressing abnormal discharge by making the texture of the target fine and uniform.

However, in these conventional techniques, there is still room for further improvement in the existence form and dispersion form of the oxide in the target, and a sputtering target capable of more effectively suppressing abnormal discharge and preventing generation of particles is desired. In particular, since the perpendicular recording system has become the mainstream, the flying height of a magnetic head in a magnetic recording device such as a hard disk drive has been reduced year by year as the recording density has been increased, and thus the requirements for the size and the number of particles allowed for a magnetic recording medium have become more and more strict.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5375707

Patent document 2: international publication No. 2014/125897

Patent document 3: international publication No. 2013/125469

Patent document 4: japanese patent No. 4975647

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a magnetic material sputtering target in which nonmagnetic material particles are dispersed, which can effectively reduce abnormal discharge and particle generation caused by oxides, particularly oxides that grow coarsely, in the sputtering target, and a method for producing the magnetic material sputtering target.

Means for solving the problems

The present inventors have conducted intensive studies in order to solve the above problems, and as a result, have found that: when an oxide having a low melting point is contained in the sputtering target, there arises a problem that the oxide melts, aggregates, or reacts with another oxide in the sintering step, and grows into aggregates having an excessively large particle size, and by heat-treating the oxide in advance before sintering, the generation of such aggregates can be suppressed, whereby the amount of generation of particles due to the oxide during sputtering can be reduced.

Based on such findings, the present application provides the following inventions.

1) A magnetic material sputtering target comprising an oxide having a melting point of 500 ℃ or lower, characterized in that the average number density of the oxide having a particle diameter of 10 μm or more in a sputtering surface of the sputtering target is 5 particles/mm²The following.

2) The magnetic material sputtering target according to 1) above, characterized by containing an oxide containing at least one selected from Cr, Ta, Ti, Si, Zr, Al, Nb, and Co as a constituent component.

3) The magnetic material sputtering target according to 1) or 2) above, wherein the total content of the oxide in the sputtering target is 5 vol% or more and 50 vol% or less.

4) The magnetic material sputtering target according to any one of the above 1) to 3), wherein the sputtering target contains 55 mol% or more and 95 mol% or less of Co, 40 mol% or less of Cr, and 45 mol% or less of Pt.

5) The magnetic material sputtering target according to 4) above, wherein the magnetic material sputtering target contains 10 mol% or less of at least one selected from the group consisting of B, N, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Si, and Al.

6) A method for producing a magnetic material sputtering target according to any one of 1) to 5), characterized by heat-treating an oxide powder containing an oxide having a melting point of 500 ℃ or lower at a temperature equal to or higher than a sintering temperature of the target, and using the heat-treated powder as a sintering material.

7) A method for producing a magnetic material sputtering target according to any one of 1) to 5), characterized by heat-treating an oxide powder other than an oxide having a melting point of 500 ℃ or lower at a temperature equal to or higher than a sintering temperature of the target, and using the heat-treated powder as a sintering material.

8) The method for producing a magnetic material sputtering target according to the above 6) or 7), wherein the method comprises a step of performing a heat treatment at 800 ℃ or higher and 1900 ℃ or lower in the atmosphere.

9) The method for producing a magnetic material sputtering target according to 6) above, wherein the method comprises a step of adjusting the particle diameter of the oxide powder after the heat treatment to an average particle diameter of 5 μm or less.

10) The method for producing a magnetic material sputtering target according to any one of the above 6) to 9), wherein the method comprises a step of hot press sintering at a holding temperature of 500 ℃ to 1400 ℃.

Effects of the invention

The magnetic material sputtering target in which the nonmagnetic material particles are dispersed according to the present invention contributes to suppression of abnormal discharge and reduction of generation of particles due to coarse oxides during sputtering, and can significantly improve characteristics as compared with conventional sputtering targets. This provides the following advantageous effects: the cost improvement effect by further improvement of the yield can be obtained.

Drawings

Fig. 1 is a schematic diagram for explaining the particle size of the oxide particles of the present invention.

FIG. 2 is a view showing the structure observation position of the sputtering target of the present invention.

Fig. 3 is a structure observation image of the sputtering target (sputtering surface side) of example 1 by a laser microscope.

Fig. 4 is a structure observation image of the sputtering target (sputtering surface side) of comparative example 1 by a laser microscope.

Fig. 5 is an EPMA element distribution image of an oxide in the sputtering target of comparative example 1.

Detailed Description

When an oxide having a melting point of 500 ℃ or lower (hereinafter, referred to as a low-melting-point oxide) is used as a raw material of the nonmagnetic material, such a low-melting-point oxide may melt during sintering and react with itself or another oxide to form an aggregate. When an oxide that has been aggregated and coarsened is present in a sintered body (sputtering target), abnormal discharge may occur from this point of origin during sputtering, or the coarsened oxide may detach and generate particles, which may cause a reduction in film quality and a reduction in product yield.

The present invention is characterized in that the oxide is heat-treated in advance to suppress the formation of aggregates caused by the melting of the oxide during sintering, thereby reducing the proportion of coarse oxide present in the sputtering target. That is, the magnetic material sputtering target of the present invention is characterized in that, when an oxide having a melting point of 500 ℃ or lower is contained as nonmagnetic material particles, the average number density of the oxide having a particle diameter of 10 μm or more present in the sputtering target is adjusted to 5 particles/mm²The following.

Fig. 1 shows the shape (schematic plan view) of an oxide present in the sputtering target. As shown in fig. 1, the planar shape of the oxide is not necessarily a perfect circle or an elliptical shape, and therefore, in the present invention, the diameter of the largest inscribed circle drawn in the planar shape of the oxide is defined as the particle diameter. Fig. 2 is a schematic view showing a tissue observation position of the sputtering target. As shown in fig. 2, the structure was observed at a total of 10 positions of the center of the target and 1/2 points of the radius (r), and the average value of the number density of oxides in each observed structure was defined as the average number density. At this time, in order to accurately grasp the shape of the oxide, observation was performed in a visual field of 1075 μm × 1433 μm.

When an oxide having a melting point of 500 ℃ or lower is used, an aggregation phenomenon during sintering occurs remarkably. Examples of the oxide having a melting point of 500 ℃ or lower include diboron trioxide (B)₂O₃)。B₂O₃Is a material frequently used as a nonmagnetic material for a magnetic material sputtering target, and therefore, although B is mentioned in the present application₂O₃However, since the same phenomenon occurs when the melting point is 500 ℃ or lower, except that B is used as the sintering material₂O₃Other oxides having a low melting point may be used.

When the sintering material contains an oxide having a melting point of 500 ℃ or lower (low-melting-point oxide), the oxide melts during sintering, and remains as coarse oxide aggregates in the sintered body. As a means for suppressing the formation of such aggregates, there is a method of: 1) a method of synthesizing compounds (composite oxides) having different melting points by heat-treating a low-melting-point oxide together with other oxides; 2) a method in which oxides other than the low melting point oxide are heat-treated in advance, whereby a reaction with the low melting point oxide (reduction in reactivity) is less likely to occur during sintering.

Examples of the oxide other than the low-melting point oxide include oxides containing at least one selected from Cr, Ta, Ti, Si, Zr, Al, Nb, and Co as a constituent component. These oxides are present in the sputtering target as oxides of single elements, or composite oxides thereof, and composite oxides with the low melting point oxide. In the sputtering target, the total content of the oxides including the low melting point oxide is preferably set to 5 vol% or more and 50 vol% or less. By setting the total volume ratio of the oxides to 5 vol% or more, good magnetic characteristics can be obtained. Further, by setting the total volume ratio of the oxides to 50 vol% or less, the oxides can be uniformly and finely dispersed. More preferably 20% by volume or more and 40% by volume or less.

The magnetic material sputtering target of the present invention contains 55 mol% to 95 mol% of Co, and as optional components, 45 mol% or less of Pt and 40 mol% or less of Cr, and Pt and Cr may be 0 mol%. The composition is determined mainly by the magnetic properties required for the magnetic recording layer. In order to control the magnetic properties more strictly, it is preferable to set the content of Co to 60 mol% or more and 85 mol% or less, the content of Pt to 25 mol% or less, and the content of Cr to 20 mol% or less. In addition, in order to improve the magnetic properties, it is effective to contain 10 mol% or less of at least one selected from the group consisting of B, N, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Si and Al.

The magnetic material sputtering target of the present invention can be produced by a powder sintering method, for example, by the following method.

First, Co powder, Pt powder, and Cr powder are prepared as magnetic materials, and B, Ti, and V powder are prepared as additives. For these powders, not only single-element powders but also alloy powders may be used. It is preferable to use a powder having a particle diameter in the range of 1 μm to 10 μm. When the particle size is 1 to 10 μm, more uniform mixing can be achieved, and segregation and coarse crystallization can be prevented. When the particle diameter of the metal powder is larger than 10 μm, the nonmagnetic material may not be uniformly dispersed, and when the particle diameter of the metal powder is smaller than 1 μm, there may be a problem that the composition of the target deviates from a desired composition due to the influence of oxidation of the metal powder. It should be noted that the range of the particle size is merely a preferable range, and the exceeding of the range is not a condition for negating the present invention.

A powder of an oxide containing Cr, Ta, Ti, Si or the like as a constituent component, including an oxide having a melting point of 500 ℃ or lower, is prepared as a nonmagnetic material. It is desirable to use a powder having an oxide particle size in the range of 1 to 5 μm. When the particle size is equal to or smaller than the particle size of the metal powder, the metal powder can be easily pulverized, and when the powder is mixed with the metal powder, the nonmagnetic material powder is less likely to aggregate with each other and can be uniformly dispersed. It should be noted that the range of the particle size is merely a preferable range, and the exceeding of the range is not a condition for negating the present invention.

Next, the preliminary heat treatment of the oxide which is the key point of the present invention will be described. As described above, since an oxide having a melting point of 500 ℃ or less is melted at the time of sintering of a target and an aggregate is easily generated, the present invention is characterized in that 1) a low-melting-point oxide is synthesized into a composite oxide having a higher melting point or 2) the reactivity of an oxide other than the low-melting-point oxide is reduced by heat-treating the oxide at a temperature higher than the sintering temperature of the target in advance.

As described above 1), by heat-treating a mixed powder of an oxide having a melting point of 500 ℃ or lower (low-melting-point oxide) and another oxide (i.e., an oxide having a melting point higher than 500 ℃) at a temperature equal to or higher than the sintering temperature of the target, the low-melting-point oxide and the other oxide are synthesized to form a composite oxide having a higher melting point, whereby aggregation accompanied by melting of the oxides at the time of sintering the target can be suppressed.

As described above 2), only the oxide other than the oxide having a melting point of 500 ℃ or less (low-melting-point oxide) (oxide having a melting point higher than 500 ℃) is heat-treated at a temperature equal to or higher than the sintering temperature of the target, whereby the reaction with the low-melting-point oxide during sintering of the target is suppressed, and the coarsening of the oxide is suppressed.

The heat treatment of the oxide powder is performed at a sintering temperature of the target or higher, and preferably 800 ℃ to 1900 ℃ in the air. When the temperature is less than 800 ℃, the effect of the heat treatment of the oxide powder may be insufficient, while when the temperature is more than 1900 ℃, the energy cost is undesirably increased. The heat treatment time of the oxide powder is preferably 2 hours or more. After the heat treatment of the oxide powder, the oxide powder is preferably pulverized using a mortar or the like so that the particle diameter is adjusted to an average particle diameter of 5 μm or less. If the powder has an average particle diameter of 5 μm or less, the nonmagnetic material powder is less likely to aggregate with each other when mixed with the metal powder, and can be uniformly dispersed.

Next, the above-described raw material powder and the oxide heat-treated powder are weighed to obtain a desired composition, and are mixed while being pulverized by a known method such as a ball mill. Thereafter, the obtained mixed powder is molded and sintered in a vacuum atmosphere or an inert gas atmosphere by a hot press method. In addition to the hot pressing, various pressure sintering methods such as a discharge plasma sintering method can be used. In particular, the hot isostatic pressing sintering method is effective for increasing the density of the sintered body. The holding temperature at the time of sintering of the target depends on the composition of the target components, and is preferably set in a temperature range of 500 ℃ to 1400 ℃. The sintered body thus obtained is machined into a desired shape by a lathe, whereby the sputtering target of the present invention can be produced.

The evaluation methods of the present invention including examples and comparative examples described later are as follows.

(Observation of the texture of the target and the number density of oxide particles)

The tissue of the target surface is evaluated using a magnified image obtained by a laser microscope. As shown in fig. 2, on the target surface subjected to pretreatment such as polishing and cleaning, a total of 10 points of the center (1 point) and radius 1/2 (9 points) of the target were observed for the tissue using a laser microscope, and the observed images were taken. Regarding the observation magnification, the viewing area 1075 μm × 1433 μm was set so that the shape of the oxide could be accurately evaluated. Next, the extracted tissue image of 10 points is converted into a binarized image. The threshold value at the time of binarization is set between the difference in color tone at the boundary between the matrix mainly containing the metal component and the oxide particle. Usually, the boundary between the matrix and the oxide particles can be clearly recognized by the contrast difference between the two, but the separation accuracy may be improved by a combination of processing such as discriminant analysis and differential histogram. Then, the observed image of each point of the 10-point observed image thus binarized was counted, the number of oxide particles having a particle diameter of 10 μm or more was counted, the number density per unit area obtained by dividing the counted number by the observed field area was calculated, and the average value (number density) of the 10 points was obtained.

(regarding the volume ratio of the oxide in the target)

In the present invention, the volume ratio of the oxide in the sputtering target is defined as an area ratio (area ratio [% ]) corresponding to the oxide in the entire observation field in the observation image obtained by the laser microscope]Oxide area [ μm ] obtained by binary analysis²]Area of visual field [ mu m ]²]X 100) was evaluated. The area ratio of the oxide in the entire observation field is actually the ratio of the area displayed by the oxide in the two-dimensional plane, and is not a three-dimensional spaceHowever, on the premise that the particles are isotropically dispersed in all directions, the area ratio in the two-dimensional plane can be regarded as the volume ratio in the three-dimensional space. It was confirmed that the volume ratio (vol%) of the oxide evaluated from the observation image was not significantly different from the volume ratio of the oxide evaluated from the weight and density of the raw material.

Examples

The present invention will be specifically explained based on examples and the like. The following examples and the like are described as specific examples for facilitating understanding of the technical contents of the present invention, and the technical scope of the present invention is not limited by these specific examples.

(example 1, comparative example 1)

Co powder having an average particle size of 3 μm, Pt powder having an average particle size of 3 μm, and Cr powder having an average particle size of 3 μm were prepared as raw material powders for metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder, TiO with an average particle size of 1 μm₂Powder, SiO having an average particle diameter of 1 μm₂Powder of Cr having an average particle diameter of 1 μm₂O₃Powder, CoO powder having an average particle diameter of 1 μm as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 70Co-4Cr-10Pt-4B₂O₃-2TiO₂-2SiO₂-2Cr₂O₃-6CoO mol%

Next, in example 1, TiO as a raw material powder of the oxide component was added₂Powder, SiO₂Powders the two oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment was carried out at 1050 ℃ for 5 hours in an atmospheric atmosphere at normal pressure. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 1, heat treatment was not performed.

Next, the heat-treated oxide powder (example 1 only), the non-heat-treated oxide powder, and the raw material powder of the metal component were mixed by a planetary mixer having a ball capacity of about 7 litersThe powder was mixed and pulverized for 10 minutes, and then mixed with TiO as a pulverizing medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and the ball mill pot was rotated for 20 hours to mix the balls. Next, the obtained mixed powder was filled in a carbon mold, and hot-pressed under conditions of a temperature of 850 ℃, a holding time of 2 hours, and a pressing pressure of 30MPa in a vacuum atmosphere, to obtain a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was polished and observed for texture by a laser microscope. Fig. 3 (example 1) and 4 (comparative example 1) show the respective tissue images. The average number of particles in 10 visual fields of the oxide having a particle diameter of 10 μm or more, which was present in the texture image having a visual field area of 1075 μm × 1433 μm, was 2.9 in example 1, and the average number density was 1.88 particles/mm²The scope of the present invention is satisfied. On the other hand, in comparative example 1, the number of the cells was 12.5, and the average number density was 8.11 cells/mm²Outside the scope of the invention.

Here, the element distribution diagram of the oxide in the sputtering target of comparative example 1 obtained by an electron beam microanalyzer (EPMA) is shown. As shown in FIG. 5, the oxide was confirmed to be a composite oxide containing Co-B-O, Si-B-O. It is considered that this is B at the time of sintering₂O₃Melting and aggregating to form the product.

Next, the sputtering target was mounted on a DC magnetron sputtering apparatus and sputtering was performed to evaluate the powder particles. The sputtering conditions were set to an input power of 1kW, a sputtering time of 20 seconds, and an Ar atmosphere pressure of 1.7 Pa. Then, the number of particles having a diameter of 0.07 μm or more adhering to the substrate was measured by a particle counter. The result is: a significant difference was observed between example 1, in which the number of grains was 51, and comparative example 1, in which the number of grains was 129.

(example 2, comparative example 2)

Co powder having an average particle size of 3 μm and Pt powder having an average particle size of 3 μm were prepared as raw material powders for the metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder, TiO with an average particle size of 1 μm₂Powder, SiO having an average particle diameter of 1 μm₂The powder is used as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 65Co-20Pt-5B₂O₃-5TiO₂-5SiO₂Mol% of

Next, in example 2, TiO as a raw material powder of an oxide component was added₂Powder, SiO₂Powders the two oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment conditions were the same as in example 1. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 2, heat treatment was not performed.

Next, the heat-treated oxide powder (example 2 only), the oxide powder not heat-treated, and the raw material powder of the metal component were mixed and pulverized for 10 minutes by a planetary mixer having a ball capacity of about 7 liters, and then mixed and pulverized with TiO as a pulverization medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and the ball mill pot was rotated for 20 hours to mix the balls. Next, the obtained mixed powder was filled in a carbon mold, and hot-pressed under conditions of a temperature of 850 ℃, a holding time of 2 hours, and a pressing pressure of 30MPa in a vacuum atmosphere, to obtain a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was observed for the texture in the same manner as in example 1, and the results thereof were: the average particle number of 10 visual fields of the oxide having a particle diameter of 10 μm or more, which was present in the texture image having a visual field area of 1075 μm × 1433 μm, was 7.0 in example 2, and the average number density was 4.54 particles/mm²The scope of the present invention is satisfied. On the other hand, the number of the cells in comparative example 2 was 10.0, and the average number density was 6.49 cells/mm²Outside the scope of the invention. Then, the target was evaluated by a sputtering test in the same manner as in example 1, and the results thereof were: about the appearance on a silicon substrateThe number of particles observed was 76 in example 2 and 88 in comparative example 2, and a significant difference was observed between the number of particles having a particle diameter of 0.07 μm or more.

(example 3, comparative example 3)

Co powder having an average particle size of 3 μm and Cr powder having an average particle size of 3 μm were prepared as raw material powders for metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder, TiO with an average particle size of 1 μm₂Powder, SiO having an average particle diameter of 1 μm₂The powder is used as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 65Co-20Cr-5B₂O₃-5TiO₂-5SiO₂Mol% of

Next, in example 3, B as a raw material powder of an oxide component₂O₃Powder, TiO₂Powder, SiO₂Powders the three oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment conditions were the same as in example 1. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 3, heat treatment was not performed.

Next, the heat-treated oxide powder (example 3 only), the oxide powder not heat-treated, and the raw material powder of the metal component were mixed and pulverized for 10 minutes by a planetary mixer having a ball capacity of about 7 liters, and then mixed and pulverized with TiO as a pulverization medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and the ball mill pot was rotated for 20 hours to mix the balls. Next, the obtained mixed powder was filled in a carbon mold, and hot-pressed under conditions of a temperature of 850 ℃, a holding time of 2 hours, and a pressing pressure of 30MPa in a vacuum atmosphere, to obtain a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was observed for the texture in the same manner as in example 1, and the results thereof were: the tissue images each having a field area of 1075 μm × 1433 μm were storedThe average particle number in 10 visual fields of the oxide having a particle diameter of 10 μm or more in example 3 was 3.5, and the average number density was 2.27 particles/mm²The scope of the present invention is satisfied. On the other hand, the number of the cells in comparative example 3 was 11.2, and the average number density was 7.27 cells/mm²Outside the scope of the invention. Then, the target was evaluated by a sputtering test in the same manner as in example 1, and the results thereof were: the number of particles having a particle diameter of 0.07 μm or more observed on the silicon substrate was 70 in example 3 and 118 in comparative example 3, and a significant difference was observed.

(example 4, comparative example 4)

Co powder having an average particle size of 3 μm and Cr powder having an average particle size of 3 μm were prepared as raw material powders for metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder, TiO with an average particle size of 1 μm₂The powder is used as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 65Co-20Cr-5B₂O₃-10TiO₂Mol% of

Next, B as a raw material powder of the oxide component₂O₃Powder, TiO₂Powders the two oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment was carried out at 950 ℃ for 5 hours in an atmospheric atmosphere at normal pressure. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 4, heat treatment was not performed.

Next, the heat-treated oxide powder (example 4 only), the oxide powder not heat-treated, and the raw material powder of the metal component were mixed and pulverized for 10 minutes by a planetary mixer having a ball capacity of about 7 liters, and then mixed and pulverized with TiO as a pulverization medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and were rotated for 20 hours to mix them. Then, the obtained mixed powder was filled into a carbon mold and charged under vacuum atmosphere at 850 ℃, a holding time of 2 hours and a pressure of 30MPaHot pressing was performed, thereby obtaining a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was observed for the texture in the same manner as in example 1, and the results thereof were: the average particle number of 10 visual fields of the oxide having a particle diameter of 10 μm or more, which was present in the texture image having a visual field area of 1075 μm × 1433 μm, was 7.2 in example 4, and the average number density was 4.67 particles/mm²The scope of the present invention is satisfied. On the other hand, the number of the cells in comparative example 4 was 15.5, and the average number density was 10.06 cells/mm²Outside the scope of the invention. Then, the target was evaluated by a sputtering test in the same manner as in example 1, and the results thereof were: the number of particles having a particle diameter of 0.07 μm or more observed on the silicon substrate was 98 in example 4 and 217 in comparative example 2, and a significant difference was observed.

(example 5, comparative example 5)

Co powder having an average particle size of 3 μm and Cr powder having an average particle size of 3 μm were prepared as raw material powders for metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder, SiO having an average particle diameter of 1 μm₂The powder is used as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 65Co-20Cr-5B₂O₃-10SiO₂Mol% of

Next, in example 5, B as a raw material powder of an oxide component₂O₃Powder, SiO₂Powders the two oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment was carried out at 850 ℃ for 5 hours in an atmospheric atmosphere at normal pressure. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 5, heat treatment was not performed.

Next, the heat-treated oxide powder (example 5 only) and the oxide powder which was not heat-treated were mixed by a planetary mixer having a ball capacity of about 7 litersThe powder and the raw material powder of the metal component were mixed and pulverized for 10 minutes, and then mixed with TiO as a pulverization medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and the ball mill pot was rotated for 20 hours to mix the balls. Next, the obtained mixed powder was filled in a carbon mold, and hot-pressed under conditions of a temperature of 850 ℃, a holding time of 2 hours, and a pressing pressure of 30MPa in a vacuum atmosphere, to obtain a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was observed for the texture in the same manner as in example 1, and the results thereof were: the average particle number of 10 visual fields of the oxide having a particle diameter of 10 μm or more, which was present in the texture image having a visual field area of 1075 μm × 1433 μm, was 5.1 in example 5, and the average number density was 3.31 particles/mm²The scope of the present invention is satisfied. On the other hand, in comparative example 5, the number of the cells was 7.9, and the average number density was 5.13 cells/mm²Outside the scope of the invention. Then, the target was evaluated by a sputtering test in the same manner as in example 1, and the results thereof were: the number of particles having a particle diameter of 0.07 μm or more observed on the silicon substrate was 66 in example 5 and 77 in comparative example 5, and a significant difference was observed.

(example 6, comparative example 6)

Co powder having an average particle size of 3 μm and Cr powder having an average particle size of 3 μm were prepared as raw material powders for metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder of Cr having an average particle diameter of 1 μm₂O₃The powder is used as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 65Co-20Cr-5B₂O₃-10Cr₂O₃Mol% of

Next, in example 6, B as a raw material powder of an oxide component was added₂O₃Powder of Cr₂O₃Powders the two oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment being at atmospheric pressureThe reaction was carried out at 850 ℃ for 5 hours under an atmospheric atmosphere. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 6, heat treatment was not performed.

Next, the heat-treated oxide powder (example 6 only), the oxide powder not heat-treated, and the raw material powder of the metal component were mixed and pulverized for 10 minutes by a planetary mixer having a ball capacity of about 7 liters, and then mixed and pulverized with TiO as a pulverization medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and the ball mill pot was rotated for 20 hours to mix the balls. Next, the obtained mixed powder was filled in a carbon mold, and hot-pressed under conditions of a temperature of 850 ℃, a holding time of 2 hours, and a pressing pressure of 30MPa in a vacuum atmosphere, to obtain a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was observed for the texture in the same manner as in example 1, and the results thereof were: the average particle number of 10 visual fields of the oxide having a particle diameter of 10 μm or more, which was present in the texture image having a visual field area of 1075 μm × 1433 μm, was 7.1 in example 6, and the average number density was 4.61 particles/mm²The scope of the present invention is satisfied. On the other hand, in comparative example 6, the number of the cells was 14.3, and the average number density was 9.28 cells/mm²Outside the scope of the invention. Then, the target was evaluated by a sputtering test in the same manner as in example 1, and the results thereof were: the number of particles having a particle diameter of 0.07 μm or more observed on the silicon substrate was 102 in example 6 and 182 in comparative example 6, and a significant difference was observed.

(example 7, comparative example 7)

Co powder having an average particle size of 3 μm and Cr powder having an average particle size of 3 μm were prepared as raw material powders for metal components, and B powder having an average particle size of 1 μm was prepared₂O₃Powder, Ta having an average particle diameter of 1 μm₂O₅The powder is used as a raw material powder of the oxide component. These powders were weighed to obtain the following compositions in molar ratio. The composition is shown below.

Consists of the following components: 65Co-20Cr-5B₂O₃-10Ta₂O₅Mol% of

Next, in example 7, B as a raw material powder of an oxide component₂O₃Powder, Ta₂O₅Powders the two oxide powders were mixed, and the mixed powder was subjected to heat treatment. The heat treatment was carried out at 1050 ℃ for 5 hours in an atmospheric atmosphere at normal pressure. The oxide powder after heat treatment is cooled to room temperature by furnace cooling, and then is subjected to a subsequent mixing process. On the other hand, in comparative example 7, heat treatment was not performed.

Next, the heat-treated oxide powder (example 7 only), the oxide powder not heat-treated, and the raw material powder of the metal component were mixed and pulverized for 10 minutes by a planetary mixer having a ball capacity of about 7 liters, and then mixed and pulverized with TiO as a pulverization medium₂The balls were sealed together in a ball mill pot having a capacity of 10 liters, and the ball mill pot was rotated for 20 hours to mix the balls. Next, the obtained mixed powder was filled in a carbon mold, and hot-pressed under conditions of a temperature of 850 ℃, a holding time of 2 hours, and a pressing pressure of 30MPa in a vacuum atmosphere, to obtain a sintered body. Then, the resultant was cut to obtain a disk-shaped sputtering target having a diameter of 165.1mm and a thickness of 5 mm.

The obtained sputtering target was observed for the texture in the same manner as in example 1, and the results thereof were: the average particle number of 10 visual fields of the oxide having a particle diameter of 10 μm or more, which was present in the texture image having a visual field area of 1075 μm × 1433 μm, was 74.3 in example 7, and the average number density was 2.79 particles/mm²The scope of the present invention is satisfied. On the other hand, the number of the cells in comparative example 7 was 11.5, and the average number density was 7.47 cells/mm²Outside the scope of the invention. Then, the target was evaluated by a sputtering test in the same manner as in example 1, and the results thereof were: the number of particles having a particle diameter of 0.07 μm or more observed on the silicon substrate was 84 in example 7 and 161 in comparative example 7, and a significant difference was observed.

The above results are shown in table 1.

Industrial applicability

The present invention can suppress aggregation caused by a low-melting-point oxide in particular in the structure of a magnetic material sputtering target, and can suppress abnormal discharge caused by a coarse oxide during sputtering and reduce the generation of particles. Thereby, the following excellent effects are obtained: the cost improvement effect due to the yield improvement can be further increased. The present invention is useful as a magnetic material sputtering target for forming a magnetic thin film of a magnetic recording medium, particularly a recording layer of a hard disk drive.

Claims

1. A magnetic material sputtering target comprising an oxide having a melting point of 500 ℃ or lower, characterized by further comprising an oxide containing at least one selected from the group consisting of Cr, Ta, Ti, Zr, Al and Nb as a constituent,

in the sputtering target, Co is 65 mol% or more and 70 mol% or less, Cr is 20 mol% or less, Pt is 25 mol% or less, and

the sputtering target has an average number density of 5 oxides having a particle diameter of 10 μm or more on the sputtering surface²The following.

2. The magnetic material sputtering target according to claim 1, wherein the total content of the oxide in the sputtering target is 5% by volume to 50% by volume.

3. The magnetic material sputtering target according to claim 1 or 2, wherein the magnetic material sputtering target contains 10 mol% or less of at least one selected from the group consisting of B, N, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Si, and Al.

4. A method of manufacturing a magnetic material sputtering target, said magnetic material sputtering targetThe sputtering target contains an oxide having a melting point of 500 ℃ or lower, and the average number density of the oxide having a particle diameter of 10 [ mu ] m or more on the sputtering surface of the sputtering target is 5 pieces/mm²An oxide powder containing an oxide having a melting point of 500 ℃ or lower is heat-treated at a temperature equal to or higher than the sintering temperature of the target, and the heat-treated powder is used as a sintering material.

5. The method for producing a magnetic material sputtering target according to claim 4, wherein the method comprises a step of performing a heat treatment in the atmosphere at 800 ℃ to 1900 ℃.

6. The method of manufacturing a magnetic material sputtering target according to claim 4, wherein the method comprises a step of adjusting the particle diameter of the oxide powder after the heat treatment to an average particle diameter of 5 μm or less.

7. The method for producing a magnetic material sputtering target according to any one of claims 4 to 6, wherein the method comprises a step of performing hot press sintering at a holding temperature of 500 ℃ to 1400 ℃.

8. A method for producing a magnetic material sputtering target containing an oxide having a melting point of 500 ℃ or lower and having an average number density of 5 oxides/mm in a sputtering surface of the sputtering target, the oxides having a particle diameter of 10 [ mu ] m or more²The method is characterized in that oxide powder other than an oxide having a melting point of 500 ℃ or lower is heat-treated at a temperature equal to or higher than the sintering temperature of the target, and the heat-treated powder is used as a sintering raw material.

9. The method for producing a magnetic material sputtering target according to claim 8, wherein the method comprises a step of performing heat treatment at 800 ℃ to 1900 ℃ in the atmosphere.

10. The method for producing a magnetic material sputtering target according to claim 8 or 9, wherein the method comprises a step of hot press sintering at a holding temperature of 500 ℃ to 1400 ℃.