JP2012117147A - Sputtering target with remained cobalt oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target, in which cobalt oxide of a required quantity remains, which generates less particles in sputtering, and which has a sufficient sintering density.SOLUTION: The sputtering target is made of a sintered compact consisting of a ferromagnetic alloy, which contains ≤20 mol% Cr and the balance Co, and a non-metallic inorganic material. The non-metallic inorganic material has a volume fraction of ≤40 vol.% and contains at least a cobalt oxide and a boron oxide. The sintered compact for a sputtering target is manufactured by molding and sintering a mixed powder at a retention temperature of ≤800°C by use of a pressure sintering apparatus, wherein the mixed powder is obtained by pulverizing and mixing a metallic powder and a non-metallic inorganic material powder containing at least a cobalt oxide and a boron oxide.

Description

  The present invention relates to a sputtering target, and more particularly to a sputtering target used for producing a magnetic recording film having a granular structure.

  In the field of magnetic recording and reproducing devices represented by hard disk devices, a perpendicular magnetic recording system in which an easy axis is oriented in a direction perpendicular to a recording surface has been put into practical use. In particular, in hard disk media using the perpendicular magnetic recording method, magnetic crystal grains oriented in the vertical direction are surrounded by nonmagnetic materials to reduce the magnetic interaction between the magnetic grains in order to increase recording density and reduce noise. Magnetic films having a granular structure have been developed.

In the above granular structure type magnetic film, a ferromagnetic alloy mainly composed of Co such as a Co—Cr—Pt alloy is generally used as a magnetic particle material, and a metal oxide such as SiO ₂ or TiO ₂ is generally used as a nonmagnetic material. It has been.

  As a method for producing the above granular structure type magnetic film, a method is known in which a composite sputtering target made of a Co-based alloy and a nonmagnetic material is sputtered by a DC magnetron sputtering apparatus. Listed below are known documents in which a non-magnetic material is added to a ferromagnetic material mainly composed of a Co—Cr—Pt alloy.

  In general, a composite sputtering target made of a Co-based alloy and a nonmagnetic material is produced by a powder metallurgy method. This is because the non-magnetic material particles need to be uniformly dispersed in the alloy substrate. For example, an alloy powder having an alloy phase produced by a rapid solidification method and a powder constituting the ceramic phase are mechanically alloyed, and the powder constituting the ceramic phase is uniformly dispersed in the alloy powder, and then molded by hot pressing and magnetically generated. A method for obtaining a sputtering target for a recording medium has been proposed (Patent Document 1).

By the way, when the above-mentioned composite sputtering target is sputtered, the metal oxide may be separated into metal and oxygen, and the decomposed metal may enter the magnetic crystal particles, thereby reducing the magnetic characteristics. In order to solve this problem, Patent Document 2 proposes sputtering a sputtering target containing an appropriate amount of cobalt oxide.
This is because the metal element of the metal oxide decomposed at the time of sputtering recombines with the oxygen generated by the decomposition of the cobalt oxide, so that the metal oxide is stably segregated between the magnetic particles. is there.
The target of Patent Document 2 includes a Co alloy, a Ti oxide and a Si oxide that form a first oxide, and a Co oxide that forms a second oxide, and the first oxidation of the target. Although it is described that the total amount of the product is about 12 mol% or less in terms of mole fraction, this is an invention relating to a magnetic recording medium, and there is no definition of a composition range effective as a target.

Patent Document 3 below describes a sputtering target containing Co and Pt or Co, Cr and Pt, and SiO ₂ and / or TiO ₂ and Co ₃ O ₄ and / or CoO. In this case, the content of Co ₃ O ₄ and / or CoO is 0.1 to 10 mol%. It is described that by sintering the raw material powder at 1000 ° C. or less, reduction of oxides such as SiO ₂ , TiO ₂ , Co ₃ O ₄ and CoO can be prevented, and the relative density is 94% or more. Has been.
In addition, it is possible to prevent the reduction of CoO by sintering at 1000 ° C. or lower. In addition, paragraph [0022] discloses B ₂ O ₃ as an oxide, but includes it. There is no description of the effect.

In the following Patent Document 4, it is described that the target contains cobalt oxide.
Target 89 (63Co-17Cr-16Pt- 4B) -4 (TiO 2) -7 (CoO) is described. The target containing B and CoO is disclosed in the examples, but there is no description of the meaning or effect of adding B.

  In the following Patent Document 5, the target is a compound of Co and at least one nonmagnetic metal selected from the group of Cr, Si, Ta, Al, Ti, W, and Mg and Co. In addition, it is described that the ratio of oxygen contained in the target is higher than the ratio of oxygen contained in the perpendicular magnetic layer. In the examples, 53.5 mol% Co-8.4 is described. A target of mol% CoSi-38.2 mol% CoO and a target of 13 mol% Co-15 mol% Cr-16 mol% Pt-49 mol% CoO-7 mol% CoSi are described. However, B is not contained, and there is no disclosure of a composition range effective as a target.

 In the following Patent Document 6, the target is a Co alloy, one or more first oxides selected from the group consisting of Si, Ti, Ta, Cr, W, and Nb oxides, and a second oxide. Although a magnetic recording medium including a Co oxide that constitutes a material is described, there is no definition of a composition range effective as a target.

Japanese Patent Laid-Open No. 10-088333 JP 2009-238357 A International Publication WO20130074171 JP 2010-118115 A JP 2010-176727 A JP 2009-170052 A

  Generally, the above sputtering target is produced by pressure sintering a powder raw material in a vacuum atmosphere at a temperature of 900 ° C. or higher. However, when cobalt oxide is contained, decomposition of cobalt oxide starts when heated to 900 ° C. or higher. In particular, when an alloy component contains an element having a standard free energy of formation smaller than that of cobalt oxide such as Cr, the cobalt oxide may be reduced by these elements even at a temperature lower than 900 ° C. Therefore, it is difficult to leave the required amount of cobalt oxide in the target.

  On the other hand, if the sintering temperature is set to 800 ° C. or lower, the proportion of cobalt oxide remaining increases, but the powder does not sinter and only a low-density sintered body can be obtained. In this case, there arises a problem that particles (dust adhering to the substrate) greatly increase during sputtering.

  In view of the above problems, an object of the present invention is to provide a sputtering target having a sufficient sintered density in which a necessary amount of cobalt oxide remains and the generation of particles during sputtering is small.

In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, a small amount of B ₂ O ₃ was added to the target, and pressure sintering was performed at a temperature of 800 ° C. or lower. It has been found that a sputtering target having a sufficient sintered density can be obtained with the cobalt oxide remaining.

Based on such knowledge, the present invention
1) A sintered sputtering target made of a ferromagnetic alloy having a Cr content of 20 mol% or less and the balance Co and a nonmetallic inorganic material, wherein the nonmetallic inorganic material occupies a volume fraction of 40 vol% or less, and the nonmetallic A sputtering target, wherein the inorganic material contains at least cobalt oxide and boron oxide.
2) A sintered sputtering target made of a ferromagnetic alloy and a nonmetallic inorganic material with Cr of 20 mol% or less, Pt of 30 mol% or less, and the balance being Co, and the volume ratio occupied by the nonmetallic inorganic material is 40 vol% In the following, a sputtering target is provided in which the non-metallic inorganic material contains at least cobalt oxide and boron oxide.

The present invention also provides 3) the sputtering target according to 1) or 2), wherein the cobalt oxide is one or more of CoO, Co ₂ O ₃ , and Co ₃ O _4. .
The present invention also provides:
4) The sputtering target according to any one of 1) to 3), wherein a volume ratio of the boron oxide in the sputtering target is 5 vol% or more and 20 vol% or less.

The present invention also provides:
5) the boron oxide to provide a sputtering target according to any one of 1) to 4), which is a B ₂ O _3.
The present invention also provides:
6) The non-metallic inorganic material includes an oxide of one or more elements selected from Mg, Al, Si, Ti, V, Cr, Mn, Y, Zr, Nb, Ta, and Ce. A sputtering target according to any one of 1) to 5) is provided.

The present invention also provides:
7) One or more elements selected from B, Ti, V, Nb, Mo, Ru, Ta, W, Ir, and Au as additive elements are contained in the alloy in an amount of 15 mol% or less. 1) to 6) The sputtering target as described in any one of these is provided.
The present invention also provides:
8) The sputtering target according to any one of 1) to 7), wherein the relative density is 90% or more.
9) A mixed powder obtained by crushing and mixing a metal powder and a non-metallic inorganic material powder containing at least cobalt oxide and boron oxide is molded and sintered by a pressure sintering apparatus at a holding temperature of 800 ° C or lower. A method for manufacturing a sintered body for a sputtering target.

  When the sputtering target of the present invention is used, a granular structure type magnetic film having good magnetic properties can be obtained without causing a decrease in yield due to generation of particles.

  The sputtering target of the present invention is a sintered body sputtering target composed of an alloy mainly composed of Co and Cr and non-metallic inorganic material particles, and the non-metallic inorganic material particles include cobalt oxide and boron oxide.

  Further, the sputtering target of the present invention is a sintered body sputtering target made of an alloy of Cr of 20 mol% or less and the balance of Co and a non-metallic inorganic material, and the volume ratio occupied by the non-metallic inorganic material is 40 vol% or less. The reason why the composition of the alloy and the volume ratio of the nonmetallic inorganic material are in the above range is that the composition is preferable as a magnetic layer of a hard disk medium employing a perpendicular magnetic recording system.

That is, within this range, the alloy composition ratio and the volume ratio of the nonmetallic inorganic material can be selected arbitrarily according to the characteristics required for the magnetic film. In addition, the object of the present invention to leave cobalt oxide in the target at a high relative density can be achieved by containing boron oxide in the target.
This is because the melting point of boron oxide is sufficiently lower than the decomposition temperature of cobalt oxide, so that a sufficiently dense sintered material can be obtained as a sputtering target even at a temperature lower than the decomposition temperature of cobalt oxide.

  The Cr is added as an essential component and excludes 0 mol%. That is, it contains at least a Cr amount that is at least the lower limit that can be analyzed. If the amount of Cr is 20 mol% or less, there is an effect even when a small amount is added. The present invention includes these. These are components required as a magnetic recording medium, and the mixing ratio varies within the above range, but any of them can maintain the characteristics as an effective magnetic recording medium.

In the above component composition, Pt can be further added. Again, 0 mol% is excluded. That is, it contains at least a Pt amount that is at least the lower limit that can be analyzed. If the amount of Pt is 30 mol% or less, there is an effect even when a small amount is added.
The present invention includes these. These are components required as a magnetic recording medium, and the mixing ratio varies within the above range, but any of them can maintain the characteristics as an effective magnetic recording medium.

Moreover, the sputtering target of the present invention, as a cobalt _{oxide, CoO, Co 2 O 3,} Co 3 O 4 of may be used alone or either. Whichever cobalt oxide is used, the present invention can remain as a cobalt oxide in the target.
Moreover, it is preferable that the sputtering target of this invention sets the volume ratio of the boron oxide in a sputtering target to 5 vol% or more and 20 vol% or less. The reason why it is 5 vol% or more is that if it is less than this, the effect of boron oxide addition cannot be sufficiently obtained, and the density of the sintered body is difficult to increase. Further, the reason why it is 20 vol% or less is that if it is more than that, there is a possibility that the characteristics as a magnetic recording film may be impaired.

Boron oxide is mainly diboron trioxide (B ₂ O ₃ ), but boron oxide (BO), diboron oxide (B ₂ O), hexaboron oxide (B ₆ O), other High boron oxide or the like can be used. Furthermore, oxygen excess, boron excess, etc. may be used. In the present invention, since all have the same effect as diboron trioxide (B 2 _{O 3),} the present invention is intended to embrace all these.

The sputtering target of the present invention uses an oxide of one or more elements selected from Mg, Al, Si, Ti, V, Cr, Mn, Y, Zr, Nb, Ta, and Ce as a non-metallic inorganic material. be able to. These oxides have a higher standard free energy of formation than cobalt oxide, and recombine with oxygen generated by the decomposition of cobalt oxide during sputtering to form oxides and precipitate at the grain boundaries. Is preferred.
Further, the sputtering target of the present invention may contain one or more elements selected from B, Ti, V, Nb, Mo, Ru, Ta, W, Ir, and Au as additive elements in a proportion of 15 mol% or less. it can. These elements are added as necessary to further improve the characteristics of the magnetic recording film.

Moreover, the sputtering target of this invention can make the relative density of a target 90% or more in order to suppress the particle | grain generation by a density shortage. More preferably, it is 95% or more.
Here, the relative density is a value obtained by dividing the measured density of the sputtering target by the calculated density (also called the theoretical density). The calculation density is a density when it is assumed that the constituent components of the target are mixed without diffusing or reacting with each other, and is calculated by the following equation.
Formula: Calculated density = Σ (Molecular weight of constituent component × Molar ratio of constituent component) / Σ (Molecular weight of constituent component × Molar ratio of constituent component / Document value density of constituent component)
Here, Σ means taking the sum for all the constituent components of the target. The actual density of the sputtering target is measured by the Archimedes method.

Metal powder and non-metallic inorganic material powder are used as starting materials. It is desirable to use a metal powder having a maximum particle size of 20 μm or less. Moreover, not only a single element metal powder but also an alloy powder can be used. In that case also, it is desirable that the maximum particle size be 20 μm or less.
On the other hand, if the particle size is too small, there is a problem that the oxidation of the metal powder is promoted and the component composition does not fall within the range.
Moreover, since the nonmetallic inorganic material powder containing cobalt oxide and B ₂ O ₃ needs to be finely dispersed in the alloy, it is desirable to use a powder having a maximum particle size of 5 μm or less. On the other hand, if the particle size is too small, it tends to agglomerate.

  First, the above metal powder and non-metallic inorganic material powder are weighed to have a desired composition. Next, the weighed metal powder and non-metallic inorganic material powder are pulverized and mixed by a known method such as a ball mill. The mixed powder thus obtained is molded and sintered with a hot press. In addition to hot pressing, a plasma discharge sintering method or a hot isostatic pressing method can also be used. The holding temperature during sintering is set to 800 ° C. or lower. Preferably it is 750 degrees C or less. The sintered body for sputtering target of the present invention can be manufactured through the above steps.

  Hereinafter, description will be made based on Examples and Comparative Examples. In addition, a present Example is an example to the last, and is not restrict | limited at all by this example. In other words, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in the present invention.

Example 1
In Example 1, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, and a Pt powder having an average particle size of 5 μm were used as the metal raw material powder, and an SiO ₂ powder having an average particle size of 1 μm was used as the nonmetallic inorganic material particle powder. CoO powder having an average particle diameter of 1 μm and B ₂ O ₃ powder having an average particle diameter of 5 μm were prepared. These powders were weighed at the following composition ratio.
The composition is as follows. _{61Co-13.3Cr-9.5Pt-3.6SiO 2} -7.6CoO-5B 2 O 3 (mol%)

Next, the weighed powder was sealed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed.
The hot pressing conditions were a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 800 ° C., and a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 95%. The composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of CoO was calculated based on the analysis result. As a result, 92% of the charged amount of CoO remained.

(Comparative Example 1)
In Comparative Example 1, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, and a Pt powder having an average particle size of 5 μm were used as the metal raw material powder, and an SiO ₂ powder having an average particle size of 1 μm was used as the nonmetallic inorganic material particle powder. CoO powder having an average particle diameter of 1 μm was prepared. These powders were weighed at the following composition ratio. The composition is as follows. 60Co-14Cr-10Pt-8SiO2-8CoO (mol%)

  Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The conditions for hot pressing were the same as in Example 1, a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 800 ° C., and a holding time of 2 hours, and the pressure was increased from 30 MPa to the end of holding. Moreover, it was naturally cooled after completion | finish of holding | maintenance. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 78%. The composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of CoO was calculated based on the analysis result. As a result, 94% of the charged amount of CoO remained.

(Comparative Example 2)
In Comparative Example 2, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, and a Pt powder having an average particle size of 5 μm were used as the metal raw material powder, and an SiO ₂ powder having an average particle size of 1 μm was used as the nonmetallic inorganic material particle powder. CoO powder having an average particle diameter of 1 μm was prepared. These powders were weighed at the following composition ratio. The composition is as follows. 60Co-14Cr-10Pt-8SiO2-8CoO (mol%)

  Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The hot pressing conditions were a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 1000 ° C., and a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 95%. In addition, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the remaining amount of CoO was calculated based on the analysis result. As a result, 97% of the input amount of CoO was decomposed (only 3% remained). I did n’t.)

Comparing the results of these Examples and Comparative Examples, in Comparative Example 1 in which B ₂ O ₃ was not added, the residual amount of CoO was almost the same as that of Example 1, but the relative density was very low and it was practically used. It is not possible. On the other hand, in Comparative Example 2, a sputtering target having the same density as in Example 1 was obtained, but the sintering temperature was high and CoO was almost completely decomposed.

(Example 2)
In Example 2, Co powder having an average particle size of 3 μm and Cr powder having an average particle size of 5 μm were used as the metal raw material powder, and TiO ₂ powder having an average particle size of 1 μm and Co ₃ O having an average particle size of 3 μm were used as the nonmetallic inorganic material particle powder. _Four powders and B ₂ O ₃ powder having an average particle size of 5 μm were prepared. These powders were weighed at the following composition ratio. The composition is as follows. _{62.72Co-19.6Cr-13.72TiO 2 -1.96Co 3} O 4 -2B 2 O 3 (mol%).

Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The hot pressing conditions were a vacuum atmosphere, a temperature rising rate of 300 ° C./hour, a holding temperature of 750 ° C., a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding.
In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

At this time, the relative density of the sputtering target was 93%. In addition, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of Co ₃ O ₄ was calculated based on the analysis result. As a result, 90% of the input amount of Co ₃ O ₄ remained. It was.

(Comparative Example 3)
In Comparative Example 3, Co powder having an average particle diameter of 3 μm and Cr powder having an average particle diameter of 5 μm were used as the metal raw material powder, and TiO ₂ powder having an average particle diameter of 1 μm and Co ₃ O having an average particle diameter of 3 μm were used as the nonmetallic inorganic material particle powder. _Four powders were prepared. These powders were weighed at the following composition ratio.
The composition is as follows. _{64Co-20Cr-14TiO 2 -2Co 3} O 4 (mol%)

Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The conditions for hot pressing were the same as in Example 2, with a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 750 ° C., and a holding time of 2 hours. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.
At this time, the relative density of the sputtering target was 83%. Further compositionally analyzed pieces taken from the target in the ICP emission spectrometer, the calculated residual amount of Co ₃ O ₄ on the basis of the analysis result, 92% of Co ₃ O ₄ of the input amount remained It was.

(Comparative Example 4)
In Comparative Example 4, Co powder having an average particle diameter of 3 μm and Cr powder having an average particle diameter of 5 μm were used as the metal raw material powder, and TiO ₂ powder having an average particle diameter of 1 μm and Co ₃ O having an average particle diameter of 3 μm were used as the nonmetallic inorganic material particle powder. _Four powders were prepared. These powders were weighed at the following composition ratio.
The composition is as follows. _{64Co-20Cr-14TiO 2 -2Co 3} O 4 (mol%)

  Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The hot pressing conditions were a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 1000 ° C., and a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. Moreover, it was naturally cooled after completion | finish of holding | maintenance. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

At this time, the relative density of the sputtering target was 98%. In addition, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of Co ₃ O ₄ was calculated based on the analysis result. As a result, 99% of the input amount of Co ₃ O ₄ was decomposed. (Only 1% remained).

Comparing the results of these Examples and Comparative Examples, in Comparative Example _{3 in} which B ₂ O ₃ was not added, the remaining amount of cobalt oxide was almost the same as in Example 2, but the relative density was very low and practical. It is not something that can be used.
On the other hand, in Comparative Example 4, a dense sputtering target substantially the same as in Example 2 was obtained, but the sintering temperature was high and the cobalt oxide was almost completely decomposed.

(Example 3)
In Example 3, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, a Pt powder having an average particle size of 5 μm, and a Ru powder having an average particle size of 8 μm are averaged as nonmetallic inorganic material particle powders. A TiO ₂ powder having a particle diameter of 1 μm, a SiO ₂ powder having an average particle diameter of 1 μm, a CoO powder having an average particle diameter of 1 μm, and a B ₂ O ₃ powder having an average particle diameter of 5 μm were prepared. These powders were weighed at the following composition ratio.
The composition is as follows. _{62.64Co-4.35Cr-13.92Pt-6.09Ru-} 2TiO2-3SiO 2 -6CoO-2B 2 O 3 (mol%)

Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed.
The hot pressing conditions were a vacuum atmosphere, a temperature rising rate of 300 ° C./hour, a holding temperature of 750 ° C., a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 97%. In addition, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of CoO was calculated based on the analysis result. As a result, 82% of the charged amount of CoO remained.

(Comparative Example 5)
In Comparative Example 5, Co powder having an average particle size of 3 μm, Cr powder having an average particle size of 5 μm, Pt powder having an average particle size of 5 μm, and Ru powder having an average particle size of 8 μm are averaged as non-metallic inorganic material particle powders. A TiO ₂ powder having a particle diameter of 1 μm, a SiO ₂ powder having an average particle diameter of 1 μm, and a CoO powder having an average particle diameter of 1 μm were prepared. These powders were weighed at the following composition ratio. The composition is as follows. 61.05Co-4.24Cr-13.57Pt-5.94Ru-3.6TiO ₂ -3.8SiO ₂ -7.8CoO (mol%)

  Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The conditions for hot pressing were the same as in Example 1, a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 750 ° C., and a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 71%. The composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of CoO was calculated based on the analysis result. As a result, 83% of the charged amount of CoO remained.

(Comparative Example 6)
In Comparative Example 6, as the metal raw material powder, Co powder having an average particle size of 3 μm, Cr powder having an average particle size of 5 μm, Pt powder having an average particle size of 5 μm, and Ru powder having an average particle size of 8 μm are averaged as non-metallic inorganic material particle powders. A TiO ₂ powder having a particle diameter of 1 μm, a SiO ₂ powder having an average particle diameter of 1 μm, and a CoO powder having an average particle diameter of 1 μm were prepared. These powders were weighed at the following composition ratio. The composition is as follows. 61.05Co-4.24Cr-13.57Pt-5.94Ru-3.6TiO ₂ -3.8SiO ₂ -7.8CoO (mol%)

  Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The hot pressing conditions were a vacuum atmosphere, a temperature rising rate of 300 ° C./hour, a holding temperature of 1050 ° C., and a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 96%. In addition, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the remaining amount of CoO was calculated based on the analysis result. As a result, 99% of the input amount of CoO was decomposed (only 1% remained). I did n’t.)

Comparing the results of these examples and comparative examples, in comparative example 5 in which no B ₂ O ₃ was added, the residual amount of CoO was almost the same as in example 3, but the relative density was very low and it was practically used. It is not possible. On the other hand, in Comparative Example 6, a sputtering target having the same density as in Example 3 was obtained, but the sintering temperature was high and CoO was almost completely decomposed.

Example 4
In Example 4, as a metal raw material powder, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, a Pt powder having an average particle size of 5 μm, and a B powder having an average particle size of 20 μm are averaged as non-metallic inorganic material particle powders. A SiO ₂ powder having a particle diameter of 1 μm, a Cr ₂ O ₃ powder having an average particle diameter of ₃ μm, a CoO powder having an average particle diameter of 1 μm, and a B ₂ O ₃ powder having an average particle diameter of 5 μm were prepared. These powders were weighed at the following composition ratio. The composition is as follows. _{64.24Co-8.8Cr-13.2Pt-1.76B-} 2SiO 2 -2Cr 2 O 3 -5CoO-3B 2 O 3 (mol%).

Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The hot pressing conditions were a vacuum atmosphere, a temperature rising rate of 300 ° C./hour, a holding temperature of 750 ° C., a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding.
In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 96%. The composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of CoO was calculated based on the analysis result. As a result, 93% of the charged amount of CoO remained.

(Comparative Example 7)
As the metal raw material powder, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, a Pt powder having an average particle size of 5 μm, and a B powder having an average particle size of 20 μm, and a non-metallic inorganic material particle powder having an average particle size of 1 μm A SiO ₂ powder, a Cr ₂ O ₃ powder having an average particle diameter of ₃ μm, and a CoO powder having an average particle diameter of 1 μm were prepared. These powders were weighed at the following composition ratio.
The composition is as follows. _{63.14Co-8.65Cr-12.98Pt-1.73B-} 3SiO 2 -3Cr 2 O 3 -7.5CoO (mol%).

Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The conditions for hot pressing were the same as in Example 2, with a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 750 ° C., and a holding time of 2 hours. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.
At this time, the relative density of the sputtering target was 89%. Further, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the residual amount of CoO was calculated based on the analysis result. As a result, 91% of the charged amount of CoO remained.

(Comparative Example 8)
In Comparative Example 8, as a metal raw material powder, a Co powder having an average particle size of 3 μm, a Cr powder having an average particle size of 5 μm, a Pt powder having an average particle size of 5 μm, and a B powder having an average particle size of 20 μm are averaged as non-metallic inorganic material particle powders. A SiO ₂ powder having a particle diameter of 1 μm, a Cr ₂ O ₃ powder having an average particle diameter of ₃ μm, and a CoO powder having an average particle diameter of 1 μm were prepared. These powders were weighed at the following composition ratio.
The composition is as follows. _{63.14Co-8.65Cr-12.98Pt-1.73B-} 3SiO 2 -3Cr 2 O 3 -7.5CoO (mol%)

  Next, the weighed powder was enclosed in a ball mill pot with a capacity of 10 liters together with zirconia balls as a grinding medium, and rotated and mixed and ground for 20 hours. Next, the sintering powder taken out from the ball mill was filled in a carbon mold and hot pressed. The hot pressing conditions were a vacuum atmosphere, a heating rate of 300 ° C./hour, a holding temperature of 1100 ° C., a holding time of 2 hours, and pressurization was performed at 30 MPa from the start of heating to the end of holding. In addition, it was allowed to cool naturally after completion of the holding. The sintered body thus produced was cut with a lathe to obtain a disk-shaped target having a diameter of 180 mm and a thickness of 5 mm.

  At this time, the relative density of the sputtering target was 98%. In addition, the composition of the small piece collected from the target was analyzed with an ICP emission spectroscopic analyzer, and the remaining amount of CoO was calculated based on the analysis result. As a result, 99% of the input amount of CoO was decomposed (only 1% remained). I did n’t.)

Comparing the results of these Examples and Comparative Examples, in Comparative Example 7 in which B ₂ O ₃ was not added, the remaining amount of cobalt oxide was almost the same as in Example 4, but the relative density was very low and practical. It is not something that can be used.
On the other hand, in Comparative Example 8, a dense sputtering target substantially the same as in Example 4 was obtained, but the sintering temperature was high and almost all the cobalt oxide was decomposed.

As described above, the sputtering target of the present invention contains a boron oxide such as B ₂ O ₃ as a non-metallic inorganic material, so that it can be sufficiently produced even at a sintering temperature lower than the temperature at which the cobalt oxide decomposes. It is characterized by having a high density.

  When the sputtering target of the present invention is used, a granular type magnetic film having good magnetic properties can be obtained without causing a decrease in yield due to generation of particles. In particular, it contributes to higher recording density and lower noise in hard disk media that employ perpendicular magnetic recording.

Claims (9)

  A sintered sputtering target comprising a ferromagnetic alloy having a Cr content of 20 mol% or less and the balance Co and a nonmetallic inorganic material, wherein the nonmetallic inorganic material occupies a volume fraction of 40 vol% or less, and the nonmetallic inorganic material Contains at least cobalt oxide and boron oxide.   A sintered compact sputtering target comprising a ferromagnetic alloy having Cr of 20 mol% or less, Pt of 30 mol% or less, and the balance being Co and a nonmetallic inorganic material, wherein the volume fraction occupied by the nonmetallic inorganic material is 40 vol% or less The non-metallic inorganic material contains at least cobalt oxide and boron oxide. The sputtering target according to claim 1, wherein the cobalt oxide is one or more of CoO, Co ₂ O ₃ , and Co ₃ O ₄ .   The volume ratio which occupies in the sputtering target of the said boron oxide is 5 vol% or more and 20 vol% or less, The sputtering target as described in any one of Claims 1-3 characterized by the above-mentioned. The boron oxide provides a sputtering target according to claim 1, characterized in that the B ₂ O _3.   The non-metallic inorganic material includes an oxide of one or more elements selected from Mg, Al, Si, Ti, V, Cr, Mn, Y, Zr, Nb, Ta, and Ce. The sputtering target as described in any one of 1-5.   One or more elements selected from B, Ti, V, Nb, Mo, Ru, Ta, W, Ir, and Au as additive elements are contained in the alloy in an amount of 15 mol% or less. The sputtering target according to claim 1.   The sputtering target according to claim 1, wherein the relative density is 90% or more. Sputtering which forms and sinters the mixed powder obtained by pulverizing and mixing the metal powder and the non-metallic inorganic material powder containing at least cobalt oxide and boron oxide at a holding temperature of 800 ° C or less. A method for manufacturing a sintered body for a target.