TWI753073B - Magnetic material sputtering target and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a magnetic material sputtering target, which contains oxides with a melting point of below 500° C., and is characterized in that: in the sputtering surface of the sputtering target, the average number density of oxides with a particle size of 10 μm or more is 5/ ^mm2 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 manufacturing method thereof

The present invention relates to a magnetic material sputtering target suitable for forming a magnetic thin film used in a recording layer of a magnetic recording medium, such as a particle film of a magnetic recording medium of a hard disk using a perpendicular magnetic recording method, in particular to a magnetic material sputtering target. A magnetic material sputtering target capable of suppressing abnormal discharge during sputtering and preventing the generation of particles, and a manufacturing method thereof.

In magnetic recording media such as hard disks, thin-film magnetic materials are used as magnetic recording layers, which are formed on substrates such as glass, and these magnetic recording layers are widely used for high productivity. Magnetron sputtering method of direct current (DC) power supply. In the magnetron sputtering method, a magnet is arranged on the back of the target, and the magnetic flux leaks on the surface of the target, so that the charged particles in the discharge plasma can be bound to the magnetic flux by the Lorentz force, so that the high-density plasma can be concentrated In the vicinity of the target surface, it is a method that can realize high-speed film formation.

In the field of magnetic recording represented by hard disk drives, materials based on Co, Fe, or Ni, which are ferromagnetic metals, can be used as the material for the magnetic thin film of the magnetic recording layer responsible for recording. For example, in the recording layer of a hard disk using the in-plane magnetic recording method in which the magnetization direction of the magnetic material is set to be parallel to the recording surface, Co-Cr-based or Co- Cr-Pt based ferromagnetic alloy.

On the other hand, a perpendicular magnetic recording method in which the magnetic recording amount per recording area is increased by setting the magnetization direction of the magnetic material to be perpendicular to the recording surface has been put into practical use, and has gradually become mainstream in recent years. In the magnetic recording layer of a hard disk using this perpendicular magnetic recording method, a composite material composed of a Co-Cr-Pt based ferromagnetic alloy containing Co as a main component and a non-magnetic inorganic substance is frequently used. Moreover, the magnetic thin film of the magnetic recording medium, such as a hard disk, is produced by sputtering the magnetic material sputtering target which consists of the above-mentioned material in many cases in consideration of high productivity.

As a method for producing such a magnetic material sputtering target, a dissolution method or a powder metallurgy method can be considered. The method by which the sputtering target is fabricated depends on the required sputtering characteristics or film properties, and therefore cannot be determined uniformly. However, the sputtering target used for the recording layer of the above-described perpendicular magnetic recording method, which has become mainstream in recent years, is usually produced by powder metallurgy. The reason for this is that in the sputtering target for forming a recording layer of the perpendicular magnetic recording method, it is necessary to uniformly disperse the inorganic particles in the alloy green body, and it is difficult to realize such a structure by the dissolution method.

Heretofore, with regard to the production of magnetic material sputtering targets by powder metallurgy, methods for improving them have been attempted from several viewpoints. For example, Patent Documents 1 and 2 disclose a sintered body sputtering target in which oxide particles are dispersed in an alloy green body by powder metallurgy, and it is described that an alloy composed of a specific element is made coarse The formed particles exist in the alloy green body, thereby reducing the overall magnetic permeability of the target, increasing the magnetic flux (Path Through Flux, PTF) passing through the sputtering surface of the magnetic target, and increasing the vicinity of the sputtering surface. The increase of the film formation speed is achieved by increasing the plasma density.

In addition, as methods from other viewpoints, Patent Documents 3 and 4 disclose sintered compact sputtering targets in which oxide particles are dispersed in an alloy green body by powder metallurgy and sintered, and the following are disclosed. Technology: By controlling the shape or dispersion form of the oxide dispersed in the target, a fine and uniform structure is obtained. In these targets, the oxide as a dispersion is an insulator, so depending on its shape or the form of dispersion, it may cause abnormal discharge. Therefore, by making the microstructure of the target fine and uniform, abnormal discharge is suppressed and particles are prevented from being discharged. produce.

However, in these prior art, there is room for further improvement of the existing form or dispersion form of oxides in the target, and a sputtering target that can suppress abnormal discharge more effectively and prevent the generation of particles is expected. In particular, after the perpendicular recording method has become mainstream, the flying height of the magnetic head of a magnetic recording device such as a hard disk drive has been decreasing year by year with the increase in recording density. The requirements for the size and number of products are gradually becoming stricter.

prior art literature

Patent Literature

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

An object of the present invention is to provide a magnetic material sputtering target in which non-magnetic material particles are dispersed, and a method for producing the magnetic material sputtering target, which can effectively reduce oxides in the sputtering target, especially the coarse growth of oxides. Abnormal discharge caused by objects or generation of particles.

The inventors of the present invention have made intensive studies in order to solve the above-mentioned problems, and as a result, they have obtained the knowledge that, in the case where an oxide with a low melting point is contained in a sputtering target, the oxide is melted and aggregated in the sintering step, or it is caused by the fusion of other oxides. The problem of growth of aggregates with excessively large particle size due to reaction, and the formation of such aggregates can be suppressed by pre-heating the oxides before sintering, thereby reducing the amount of particles generated by oxides during sputtering. yield.

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

1) A magnetic material sputtering target, comprising oxides with a melting point of 500° C. or lower, characterized in that: in the sputtering surface of the sputtering target, the average number density of oxides with a particle size of 10 μm or more is 5 Pieces/ ^mm2 or less.

2) The magnetic material sputtering target according to 1) above, comprising an oxide having as a constituent one or more kinds selected from the group consisting of Cr, Ta, Ti, Si, Zr, Al, Nb, and Co.

3) The magnetic material sputtering target according to 1) or 2) above, wherein the total content of oxides 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 1) to 3) above, wherein in the sputtering target, Co is 55 mol % or more and 95 mol % or less, Cr is 40 mol % or less, and Pt is 45 mol % or less.

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

6) A method for producing a magnetic material sputtering target, which is the method for producing a magnetic material sputtering target according to any one of 1) to 5) above, wherein a temperature equal to or higher than the sintering temperature of the target is 500° C. or lower including a melting point. The oxide powder of the oxide is heat-treated, and the heat-treated powder is used as the sintering raw material.

7) A method for producing a magnetic material sputtering target, which is the method for producing a magnetic material sputtering target according to any one of the above 1) to 5), wherein the temperature equal to or higher than the sintering temperature of the target divided by the melting point is 500° C. or lower The oxide powder other than the oxide is heat treated, and the heat treated powder is used as the sintering raw material.

8) The manufacturing method of the magnetic material sputtering target of the said 6) or 7) which comprises the process of heat-processing at 800 degreeC or more and 1900 degrees C or less in air|atmosphere.

9) The method for producing a magnetic material sputtering target according to 6) above, which includes the step of adjusting the particle size of the heat-treated oxide powder to an average particle size of 5 μm or less.

10) The manufacturing method of the magnetic material sputtering target according to any one of the above 6) to 9), which comprises the step of hot pressing and sintering at a temperature of 500°C to 1400°C.

The magnetic material sputtering target in which the non-magnetic material particles are dispersed can help to suppress abnormal discharge caused by coarse oxides during sputtering and reduce the generation of fine particles, which greatly improves the characteristics compared with the conventional sputtering target. Thereby, the excellent effect that the cost improvement effect by further improvement of the yield can be obtained is exhibited.

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 position of observation of the structure of the sputtering target of the present invention.

3 is a structure observation image formed by a laser microscope of the sputtering target (sputtering surface side) of Example 1. FIG.

4 is a structure observation image formed by a laser microscope of the sputtering target (sputtering surface side) of Comparative Example 1. FIG.

FIG. 5 is an EPMA elemental mapping image of the oxide in the sputtering target of Comparative Example 1. FIG.

When an oxide having a melting point of 500° C. or lower (hereinafter referred to as a low-melting-point oxide) is used as a raw material for a non-magnetic material, there is a case in which such a low-melting-point oxide is melted during sintering, and By itself or reacting with other oxides to form agglomerates. When agglomerated and coarsened oxides are present in the sintered body (sputtering target), abnormal discharges may occur from the oxides as a starting point during sputtering, or the coarsened oxides may be detached to generate fine particles. The reason for the decline in film quality and the decline in product yield.

The present invention is characterized in that by preheating the oxides, the formation of aggregates due to the melting of the oxides during sintering is suppressed, and the presence ratio of the coarse oxides in the sputtering target is reduced. That is, the magnetic material sputtering target of the present invention is characterized in that, when the non-magnetic material particles contain oxides having a melting point of 500° C. or lower, the oxides having a particle size of 10 μm or more are present in the sputtering target. The average number density is 5 pieces/mm ² or less.

The shape (schematic plan view) of the oxide present in the sputtering target is shown in FIG. 1 . As shown in FIG. 1 , the planar shape of the oxide does not have to be a perfect circle or an ellipse, so the present invention defines the diameter of the largest inscribed circle in the planar shape of the oxide as the particle size. Moreover, in FIG. 2, the schematic diagram which shows the structure observation position of a sputtering target is shown. As shown in FIG. 2 , the structure was observed at a total of 10 sites at the center of the target and 1/2 of the radius (r), and the average value of the number density of oxides in each observed structure was taken as the average number density. At this time, in order to accurately grasp the shape of the oxide, observation was performed with a field of view of 175 μm×1433 μm.

When an oxide with a melting point of 500°C or lower is used, agglomeration at the time of sintering obviously occurs. As an oxide _whose melting|fusing point is 500 degrees C or less, diboron trioxide (B2O3 ₎ is mentioned, for example. B ₂ O ₃ is commonly used as a non-magnetic material for magnetic sputtering targets, so B ₂ O ₃ is mentioned in this application, but as long as it is an oxide whose melting point is below 500°C, the same phenomenon occurs Therefore, the present invention can also be applied when a low-melting-point oxide other than B ₂ O ₃ is used as a raw material for sintering.

When an oxide (low-melting-point oxide) having a melting point of 500° C. or lower is contained in the sintering raw material, it melts during sintering and remains in the sintered body as a coarse oxide aggregate. As means for suppressing the formation of such agglomerates, there are the following methods: 1) a method of synthesizing a compound having a different melting point (composite oxide) by heat-treating a low melting point oxide and other oxides together; 2) a method of synthesizing a compound having a different melting point in advance A method of thermally treating oxides other than low melting point oxides to make it difficult to react with low melting point oxides (reducing reactivity) during sintering.

As oxides other than low melting point oxides, oxides containing one or more selected from the group consisting of Cr, Ta, Ti, Si, Zr, Al, Nb, and Co as constituent components can be mentioned. These oxides exist in the sputtering target in the form of single-element oxides or these complex oxides, and further exist in the sputtering target in the form of complex oxides with the above-mentioned low melting point oxides. In the sputtering target, it is preferable to make the total content of oxides 5 vol % or more and 50 vol % or less including low melting point oxides. By making the total volume ratio of oxides 5 vol% or more, favorable magnetic properties can be obtained. Moreover, by setting it as 50 vol% or less, an oxide can be uniformly and finely dispersed. More preferably, it is 20 vol% or more and 40 vol% or less.

The magnetic material sputtering target of the present invention contains Co at 55 mol % or more and 95 mol % or less, Pt at 45 mol % or less, Cr at 40 mol % or less as optional components, and Pt and Cr in the sputtering target. Can be 0 mol%. Its composition is mainly determined according to the magnetic properties required for the magnetic recording layer. In order to further strictly control the magnetic properties, the content of Co is preferably 60 mol % or more and 85 mol % or less, the content of Pt is preferably 25 mol % or less, and the content of Cr is preferably 20 mol % or less. In addition, in order to improve the magnetic properties, it is more effective to contain 10 mol% or less of one or more 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 further, powders of B, Ti, V, etc. are prepared as additives. As these powders, not only single element powders but also alloy powders can be used. It is preferable to use the particle size of the range of 1-10 micrometers. If 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 size of the metal powder is larger than 10 μm, the non-magnetic material may be unevenly dispersed, and if it is less than 1 μm, the composition of the target may deviate from the desired composition due to the influence of oxidation of the metal powder. situation of the problem. Furthermore, of course, it should be understood that the particle size range is always a preferable range, and the situation that deviates from the particle size range is not a condition for negating the present invention.

As the non-magnetic material, powders of oxides containing Cr, Ta, Ti, Si and the like as constituents, including oxides having a melting point of 500° C. or less, are prepared. It is more desirable to use an oxide with a particle size in the range of 1 to 5 μm. When the particle size is equal to or smaller than that of the metal powder, it is easy to be pulverized, and when mixed with the above-mentioned metal powder, the non-magnetic material powders are difficult to agglomerate and can be uniformly dispersed. Furthermore, of course, it should be understood that the particle size range is always a preferable range, and the situation that deviates from the particle size range is not a condition for negating the present invention.

Next, the preliminary heat treatment of the oxide, which is an important aspect of the present invention, will be described. As described above, oxides with a melting point of 500° C. or lower are melted during target sintering to easily form agglomerates. Therefore, the present invention is characterized in that the oxides are previously heat-treated at a temperature higher than the sintering temperature of the target, thereby 1 ) synthesizing the low melting point oxide into a composite oxide with a higher melting point, or 2) reducing the reactivity of oxides other than the low melting point oxide.

As the above-mentioned 1), a mixed powder of oxides with a melting point of 500°C or less (low melting point oxides) and other oxides (that is, oxides with a melting point of more than 500°C) is heat-treated at a temperature higher than or equal to the sintering temperature of the target. This synthesizes the low melting point oxide and other oxides to form a composite oxide with a higher melting point, thereby suppressing the aggregation accompanying the melting of the oxide during the sintering of the target.

As the above 2), only other oxides (oxides with a melting point of more than 500°C) other than oxides with a melting point of 500°C or less (low melting point oxides) are heat-treated at a temperature higher than or equal to the sintering temperature of the target. When the target is sintered, the reaction with the low melting point oxide is suppressed, and the coarsening of the oxide is suppressed.

The heat treatment of the oxide powder is performed above the sintering temperature of the target, preferably in the air at 800°C or higher and 1900°C or lower. If the temperature is less than 800°C, the effect of the heat treatment of the oxide powder may be insufficient. On the other hand, if the temperature exceeds 1900°C, the energy cost will increase, which is not preferable. The heat treatment time of the oxide powder is preferably performed for 2 hours or more. After the heat treatment of the oxide powder, it is preferable to pulverize the oxide powder using a mortar or the like, and to adjust the particle size so that the average particle size becomes 5 μm or less. When the average particle diameter is within the range of 5 μm or less, when mixing with the above-mentioned metal powder, the non-magnetic material powders are less likely to agglomerate and can be uniformly dispersed.

Next, the above-mentioned raw material powder and oxide heat-treated powder are weighed so as to have a desired composition, and are mixed and pulverized by a known method such as a ball mill. Then, the obtained mixed powder is shaped and sintered in a vacuum environment or an inert gas environment by a hot pressing method. In addition to the above hot pressing, various pressure sintering methods such as plasma discharge sintering can also be used. In particular, the hot isostatic pressing sintering method is effective for increasing the density of the sintered body. The holding temperature during sintering of the target also depends on the composition of the target, but it is preferably set to a temperature range of 500°C to 1400°C. The sintered body obtained in this way is processed into a desired shape by a lathe, whereby the sputtering target of the present invention can be produced.

Including the Examples and Comparative Examples described below, the evaluation methods of the present invention and the like are as follows.

(About the structure observation of the target and the number density of oxide particles)

Evaluation of the structure of the target surface was performed using magnified images formed by a laser microscope. On the target surface subjected to pretreatment such as grinding and cleaning, as shown in Figure 2, a total of 10 points in the center (1 point) and 1/2 radius (9 points) of the target were used to observe the structure of the target, and photographed. Observation image of each point. In order to reliably evaluate the shape of the oxide, the observation magnification was set to a visual field area of 1075 μm×1433 μm. Next, the extracted tissue image of the 10 points is converted into a binarized image. The threshold value at the time of binarization is set between the color tone difference at the boundary between the matrix mainly composed of the metal component and the oxide particles. Usually, the boundary between the matrix and the oxide can be clearly identified based on the difference in contrast between the two, and the separation accuracy can be improved by using the discriminant analysis method and the differential histogram method in combination. Next, the number of oxide particles having a particle diameter of 10 μm or more was counted for each of the 10 points of the observation image binarized as described above, and the number density per unit area obtained by dividing by the area of the observation field of view was calculated. The average value (number density) of the 10 points.

(Regarding the volume ratio of oxide in the target)

In the present invention, the volume ratio of the oxide in the sputtering target is evaluated as the area ratio corresponding to the oxide in the entire observation field in the above-mentioned observation image formed by the laser microscope (area ratio [%]= The value of oxide area [μm ² ]/visual field area [μm ² ]×100) obtained by binarization analysis. The area ratio of the oxide in the overall observation field is actually the area ratio shown by the oxide in the two-dimensional plane, not the volume ratio in the three-dimensional space, but on the premise that particles are dispersed isotropically in all directions, it can be Consider the area ratio of two-dimensional space as the volume ratio of three-dimensional space. Furthermore, it was confirmed that the volume ratio (vol %) of the oxides evaluated from the observation image and the volume ratio of the oxides evaluated from the weight and density of the raw materials were not much different.

Example

The present invention will be specifically described based on Examples and the like. The descriptions of the following examples and the like are specific examples for facilitating the understanding of the technical content of the present invention, and the technical scope of the present invention is not limited to these specific examples.

(Example 1, Comparative Example 1)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm, Pt powder with an average particle size of 3 μm, and Cr powder with an average particle size of 3 μm were prepared. B ₂ O ₃ powder, TiO ₂ powder with an average particle size of 1 μm, SiO ₂ powder with an average particle size of 1 μm, Cr ₂ O ₃ powder with an average particle size of 1 μm, and CoO powder with an average particle size of 1 μm. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 70Co-4Cr-10Pt-4B ₂ O ₃ -2TiO ₂ -2SiO ₂ -2Cr ₂ O ₃ -6CoO mol%

Next, in Example 1, two kinds of oxide powders, TiO ₂ powder and SiO ₂ powder, which are the raw material powder of the oxide component, were mixed, and the mixed powder was heat-treated. The heat treatment was carried out at 1050° C. for 5 hours in an atmospheric environment of normal pressure. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. 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 metal component raw material powder were mixed for 10 minutes in a planetary motion mixer with a ball capacity of about 7 liters. After pulverization, together with the TiO ₂ balls of the pulverization medium, it was sealed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed in a vacuum environment under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

The surface of the obtained sputtering target was ground and the structure was observed by a laser microscope. The tissue images are shown in FIG. 3 (Example 1) and FIG. 4 (Comparative Example 1), respectively. In addition, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existing in the tissue image of each visual field area of 1075 μm×1433 μm was 2.9 in Example 1, and the average number density was 1.88/ mm ² to satisfy the scope of the present invention. On the other hand, in Comparative Example 1, it was 12.5 pieces, and the average number density was 8.11 pieces/mm ² , which was out of the scope of the present invention.

Here, about the oxide in the sputtering target of Comparative Example 1, the elemental map formed by the electron probe microanalyzer (EPMA) is shown. As shown in FIG. 5 , it was confirmed that the oxide was a composite oxide composed of Co-BO and Si-BO. This composite oxide is considered to be formed by melting and aggregation of B ₂ O ₃ during sintering.

Next, a sputtering target was attached to a DC magnetron sputtering apparatus, sputtering was performed, and particle evaluation was performed. The sputtering conditions were 1 kW of input power, 20 seconds of sputtering time, and 1.7 Pa of Ar ambient pressure. Next, the number of particles with a diameter of 0.07 μm or more adhering to the substrate was measured by a particle counter. As a result, the number of fine particles was 51 in Example 1 and 129 in Comparative Example 1, and a significant difference was found.

(Example 2, Comparative Example 2)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm and Pt powder with an average particle size of 3 μm were prepared, and as the raw material powder of the oxide component, B ₂ O ₃ powder with an average particle size of 1 μm and an average particle size TiO ₂ powder with an average particle size of 1 μm and SiO ₂ powder with an average particle size of 1 μm. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 65Co-20Pt-5B ₂ O ₃ -5TiO ₂ -5SiO ₂ mol%

Next, in Example 2, two kinds of oxide powders, TiO ₂ powder and SiO ₂ powder, which are the raw material powder of the oxide component, were mixed, and the mixed powder was heat-treated. The heat treatment conditions were the same as those in Example 1. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. On the other hand, in Comparative Example 2, heat treatment was not performed.

Next, the heat-treated oxide powder (Example 2 only), the non-heat-treated oxide powder, and the raw material powder of the metal component were mixed for 10 minutes by a planetary motion type mixer with a ball capacity of about 7 liters. After mixing and pulverizing, the TiO ₂ balls as the pulverizing medium were enclosed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa in a vacuum environment to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

Regarding the obtained sputtering target, the structure of the obtained sputtering target was observed in the same manner as in Example 1. As a result, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existed in the structure image of each visual field area of 1075 μm×1433 μm. In Example 2, it was 7.0 pieces, and the average number density was 4.54 pieces/mm ² and satisfies the range of the present invention. On the other hand, in Comparative Example 2, it was 10.0 pieces, and the average number density was 6.49 pieces/mm ² , which was out of the scope of the present invention. Next, the target was evaluated by the sputtering test in the same manner as in Example 1. As a result, the number of particles with a particle diameter of 0.07 μm or more observed on the silicon substrate was 76 in Example 2 and 76 in Comparative Example 2. 88 were found to be meaningfully poor.

(Example 3, Comparative Example 3)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm and Cr powder with an average particle size of 3 μm were prepared, and as the raw material powder of the oxide component, B ₂ O ₃ powder with an average particle size of 1 μm and an average particle size of TiO ₂ powder with an average particle size of 1 μm and SiO ₂ powder with an average particle size of 1 μm. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 65Co-20Cr-5B ₂ O ₃ -5TiO ₂ -5SiO ₂ mol%

Next, in Example 3, two kinds of oxide powders, TiO ₂ powder and SiO ₂ powder, which are the raw material powder of the oxide component, were mixed, and the mixed powder was heat-treated. The heat treatment conditions were the same as those in Example 1. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. On the other hand, in Comparative Example 3, heat treatment was not performed.

Next, the heat-treated oxide powder (Example 3 only), the non-heat-treated oxide powder, and the raw material powder of the metal component were subjected to 10 minutes in a planetary motion type mixer with a ball capacity of about 7 liters. After the mixing and pulverization, the TiO ₂ balls as the pulverizing medium were enclosed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa in a vacuum environment to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

Regarding the obtained sputtering target, the structure of the obtained sputtering target was observed in the same manner as in Example 1. As a result, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existed in the structure image of each visual field area of 1075 μm×1433 μm. In Example 3, it was 3.5 pieces, and the average number density was 2.27 pieces/mm ² and satisfies the range of the present invention. On the other hand, in Comparative Example 3, it was 11.2 pieces, and the average number density was 7.27 pieces/mm ² , which was out of the scope of the present invention. Next, the target was evaluated by the sputtering test in the same manner as in Example 1. As a result, the number of particles with a particle diameter of 0.07 μm or more observed on the silicon substrate was 70 in Example 3 and 70 in Comparative Example 3. 118 were found to be meaningfully poor.

(Example 4, Comparative Example 4)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm and Cr powder with an average particle size of 3 μm were prepared, and as the raw material powder of the oxide component, B ₂ O ₃ powder with an average particle size of 1 μm and an average particle size of It is 1μm TiO ₂ powder. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 65Co-20Cr-5B ₂ O ₃ -10TiO ₂ mol%

Next, two kinds of oxide powders, B ₂ O ₃ powder and TiO ₂ powder, which are the raw material powder of the oxide component, are mixed, and the mixed powder is heat-treated. The heat treatment was carried out at 950° C. for 5 hours in an atmospheric environment of normal pressure. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. On the other hand, in Comparative Example 4, heat treatment was not performed.

Next, the heat-treated oxide powder (Example 4 only), the non-heat-treated oxide powder, and the raw material powder of the metal component were subjected to 10 minutes in a planetary motion type mixer with a ball capacity of about 7 liters. After the mixing and pulverization, the TiO ₂ balls as the pulverizing medium were enclosed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa in a vacuum environment to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

Regarding the obtained sputtering target, the structure of the obtained sputtering target was observed in the same manner as in Example 1. As a result, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existed in the structure image of each visual field area of 1075 μm×1433 μm. In Example 4, it was 7.2 pieces, and the average number density was 4.67 pieces/mm ² and satisfies the range of the present invention. On the other hand, in Comparative Example 4, it was 15.5 pieces, and the average number density was 10.06 pieces/mm ² , which was out of the scope of the present invention. Next, the target was evaluated by the sputtering test in the same manner as in Example 1. As a result, the number of particles with a particle diameter of 0.07 μm or more observed on the silicon substrate was 98 in Example 4 and 98 in Comparative Example 4. 217 were found to be meaningfully poor.

(Example 5, Comparative Example 5)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm and Cr powder with an average particle size of 3 μm were prepared, and as the raw material powder of the oxide component, B ₂ O ₃ powder with an average particle size of 1 μm and an average particle size of It is 1μm SiO ₂ powder. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 65Co-20Cr-5B ₂ O ₃ -10SiO ₂ mol%

Next, in Example 5, two oxide powders of B ₂ O ₃ powder and SiO ₂ powder as raw material powders of oxide components were mixed, and the mixed powder was heat-treated. The heat treatment was carried out at 850° C. for 5 hours in an atmospheric environment of normal pressure. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. On the other hand, in Comparative Example 5, heat treatment was not performed.

Next, the heat-treated oxide powder (Example 5 only), the non-heat-treated oxide powder, and the metal component raw material powder were subjected to 10 minutes in a planetary motion mixer with a ball capacity of about 7 liters. After the mixing and pulverization, the TiO ₂ balls as the pulverizing medium were enclosed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa in a vacuum environment to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

Regarding the obtained sputtering target, the structure of the obtained sputtering target was observed in the same manner as in Example 1. As a result, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existed in the structure image of each visual field area of 1075 μm×1433 μm. In Example 5, it was 5.1 pieces, and the average number density was 3.31 pieces/mm ² and satisfies the range of the present invention. On the other hand, in Comparative Example 5, it was 7.9 pieces, and the average number density was 5.13 pieces/mm ² , which was out of the scope of the present invention. Next, the target was evaluated by the sputtering test in the same manner as in Example 1. As a result, the number of particles with a particle diameter of 0.07 μm or more observed on the silicon substrate was 66 in Example 5 and 66 in Comparative Example 5. 77 were found to be meaningfully poor.

(Example 6, Comparative Example 6)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm and Cr powder with an average particle size of 3 μm were prepared, and as the raw material powder of the oxide component, B ₂ O ₃ powder with an average particle size of 1 μm and an average particle size of It is 1μm Cr ₂ O ₃ powder. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 65Co-20Cr-5B ₂ O ₃ -10Cr ₂ O ₃ mol%

Next, in Example 6, two oxide powders of B ₂ O ₃ powder and Cr ₂ O ₃ powder as raw material powders of oxide components were mixed, and the mixed powders were subjected to heat treatment. The heat treatment was carried out at 850° C. for 5 hours in an atmospheric environment of normal pressure. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. On the other hand, in Comparative Example 6, heat treatment was not performed.

Next, the heat-treated oxide powder (Example 6 only), the non-heat-treated oxide powder, and the raw material powder of the metal component were subjected to 10 minutes in a planetary motion mixer with a ball capacity of about 7 liters. After the mixing and pulverization, the TiO ₂ balls as the pulverizing medium were enclosed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa in a vacuum environment to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

Regarding the obtained sputtering target, the structure of the obtained sputtering target was observed in the same manner as in Example 1. As a result, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existed in the structure image of each visual field area of 1075 μm×1433 μm. In Example 6, it was 7.1 pieces, and the average number density was 4.61 pieces/mm ² and satisfies the range of the present invention. On the other hand, in Comparative Example 6, it was 14.3 pieces, and the average number density was 9.28 pieces/mm ² , which was out of the scope of the present invention. Next, the target was evaluated by a sputtering test in the same manner as in Example 1. As a result, the number of particles with a particle diameter of 0.07 μm or more observed on the silicon substrate was 102 in Example 6 and 102 in Comparative Example 6. 182 were found to be meaningfully poor.

(Example 7, Comparative Example 7)

As the raw material powder of the metal component, Co powder with an average particle size of 3 μm and Cr powder with an average particle size of 3 μm were prepared, and as the raw material powder of the oxide component, B ₂ O ₃ powder with an average particle size of 1 μm and an average particle size of It is 1μm Ta ₂ O ₅ powder. These powders were weighed so as to have the following mol ratio compositions. The composition is as follows.

Composition: 65Co-2OCr-5B ₂ O ₃ -10Ta ₂ O ₅ mol%

Next, in Example 7, two oxide powders of B ₂ O ₃ powder and Ta ₂ O ₅ powder as raw material powders of oxide components were mixed, and the mixed powders were subjected to heat treatment. The heat treatment was carried out at 1050° C. for 5 hours in an atmospheric environment of normal pressure. The oxide powder after the heat treatment is temporarily cooled to room temperature by furnace cooling and then used for the next mixing step. On the other hand, in Comparative Example 7, heat treatment was not performed.

Next, the heat-treated oxide powder (Example 7 only), the non-heat-treated oxide powder, and the raw material powder of the metal component were mixed with a planetary motion mixer with a ball capacity of about 7 liters for 10 minutes. After the mixing and pulverization, the TiO ₂ balls as the pulverizing medium were enclosed in a ball mill jar with a capacity of 10 liters, and the ball mill jar was rotated for 20 hours for mixing. Next, the obtained mixed powder was filled into a carbon mold, and hot-pressed under the conditions of a temperature of 850° C., a holding time of 2 hours, and a pressure of 30 MPa in a vacuum environment to obtain a sintered body. Further, the sintered body was machined to obtain a disk-shaped sputtering target having a diameter of 165.1 mm and a thickness of 5 mm.

Regarding the obtained sputtering target, the structure of the obtained sputtering target was observed in the same manner as in Example 1. As a result, the average number of particles in 10 visual fields of oxides with a particle size of 10 μm or more existed in the structure image of each visual field area of 1075 μm×1433 μm. In Example 7, it was 74.3 pieces, and the average number density was 2.79 pieces/mm ² and satisfies the range of the present invention. On the other hand, in Comparative Example 7, it was 11.5 pieces, and the average number density was 7.47 pieces/mm ² , which was out of the scope of the present invention. Next, the target was evaluated by a sputtering test in the same manner as in Example 1. As a result, the number of particles with a particle diameter of 0.07 μm or more observed on the silicon substrate was 84 in Example 7 and 84 in Comparative Example 7. 161 of them were found to be meaningfully poor.

The above results are shown in Table 1.

[Industrial Availability]

The present invention can suppress the agglomeration caused by the structure of the magnetic material sputtering target, especially the low melting point oxide, and can suppress the abnormal discharge caused by the coarse oxide or reduce the generation of particles during sputtering. Thereby, the excellent effect which can further expand the cost improvement effect by yield improvement is exhibited. The present invention is useful as a magnetic material thin film for forming a magnetic recording medium, particularly a magnetic material sputtering target for a recording layer of a hard disk drive.

Claims (10)

A magnetic material sputtering target, comprising oxides whose melting point is below 500°C, characterized in that: in the sputtering surface of the sputtering target, the average number density of oxides with a particle size of 10 μm or more is 5// mm ² or less, the total content of oxides in the sputtering target is 5vol%~50vol%. The magnetic material sputtering target according to claim 1 of the scope of claim 1 comprises an oxide composed of at least one selected from the group consisting of Cr, Ta, Ti, Si, Zr, Al, Nb, and Co. The magnetic material sputtering target of claim 1 or 2, wherein, in the sputtering target, Co is 55 mol% or more and 95 mol% or less, Cr is 40 mol% or less, and Pt is 45 mol% or less. According to the magnetic material sputtering target of claim 3, it contains 10 mol% or less of one selected from the group consisting of B, N, Ti, V, Mn, Zr, Nb, Ru, Mo, Ta, W, Si, and Al above. A method for manufacturing a magnetic material sputtering target, which is the method for manufacturing a magnetic material sputtering target according to any one of items 1 to 4 of the scope of the patent application, wherein the temperature above the sintering temperature of the target has a melting point of 500°C or less. The oxide powder of the oxide is heat-treated, and the heat-treated powder is used as the sintering raw material. The method for producing a magnetic material sputtering target according to claim 5 of the scope of the application includes the step of adjusting the particle size of the heat-treated oxide powder to an average particle size of 5 μm or less. A method for manufacturing a magnetic material sputtering target, which is the method for manufacturing a magnetic material sputtering target according to any one of items 1 to 4 of the patent application scope, wherein the temperature equal to or higher than the sintering temperature of the target divided by the melting point is below 500°C The oxide powder other than the oxide powder is heat-treated, and the heat-treated powder is used as the sintering raw material. The method for producing a magnetic material sputtering target according to claim 5 or 7 of the scope of the application includes the step of performing heat treatment at 800° C. or higher and 1900° C. or lower in the atmosphere. For example, the manufacturing method of the magnetic material sputtering target in any one of the 5th to 7th items of the scope of application, It includes the step of hot pressing and sintering at a temperature of 500°C to 1400°C. The manufacturing method of the magnetic material sputtering target as claimed in claim 8 of the patent application scope includes the step of hot pressing and sintering at a temperature of 500°C to 1400°C.

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