JP2000038661A - Co ALLOY TARGET, ITS PRODUCTION, APPARATUS FOR SPUTTERING, MAGNETIC RECORDING FILM AND DEVICE FOR MAGNETIC RECORDING - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Co-target, by which a uniform distribution of a composition and high film quality are stably obtained, a method for producing the same, a magnetic recording film and a magnetic recording device. SOLUTION: In a Co-alloy containing a dissolving material mainly composed of Co and having a saturated magnetic flux density of less than 0.1 T, the saturated magnetic flux density is controlled to be more than 0.1 T. A target is allowed to contain, preferably 3-30 atom % at least one selected from Ni and Pt, further preferably, >=18 atom % Cr, and >=2 atom % at least one selected from Ta, Zr, Ti and Nb, as non-magnetic metals. The objective target can be obtained by mixing one non-magnetic metal powder or non-magnetic alloy powder with one magnetic powder and then sintering while controlling the saturated magnetic flux density to be >=0.1 T. A Co magnetic recording film having coercive force of >=160 kA/m and a product of residual magnetic flux density and the film thickness of <=130 Gμm can be produced by sputtering the target by using a magnetron sputtering apparatus forming leaked magnetic flux.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Co-based target used for forming a Co-based magnetic film mainly used as a magnetic recording medium, a method of manufacturing the same, a sputtering apparatus, a magnetic recording film, and a magnetic recording apparatus. It is.

[0002]

2. Description of the Related Art A Co alloy target is mainly used when a Co alloy film to be a magnetic layer of a magnetic recording device such as a hard disk is formed by a sputtering method. Various alloys are used for the Co-based alloy film based on the magnetic properties required for the hard disk, and typical composition systems are Co-Cr-Ta-based and Co-Cr-Ta-Pt.
Systems, Co-Cr-Ni systems and the like are known. These C
The o-alloy film is formed by sputtering using a target manufactured to have the same composition as a base material. Current,
In order to efficiently form a Co alloy film, magnetron sputtering, in which a magnetic circuit is arranged on the back side of a target, is usually used.

Conventionally, a Co alloy-based target is a ferromagnetic material. At the time of the above magnetron sputtering, a magnetic flux leaking from the back surface of the target is hardly generated on the target surface, so that the use efficiency of the target is reduced and the productivity is reduced. It was noticed. For this reason, various manufacturing methods have been proposed to improve the magnetic properties of the target and improve the use efficiency. For example, Japanese Patent Publication No. 2-49384 describes that it is possible to improve the magnetic properties by applying a strain to the inside of a Co alloy by cold working to change the crystal structure, thereby improving the use efficiency.

In recent years, in order to improve the characteristics of a Co-based magnetic recording film, a CoCrPt alloy film to which expensive Pt is added has been used.
Therefore, a CoCrPt target containing expensive Pt has come to be used. Since this CoCrPt alloy has poor plastic workability and low cold workability and hot workability, various methods are used. For example, Japanese Patent Application Laid-Open No. 4-2630
In No. 69, the composition is mainly composed of Co in the range of 5 to 20 at% of Cr and 10 to 55 at% of Pt.
m or less, in Japanese Patent Application Laid-Open No. 5-98433, a method of manufacturing by sintering CoCrPt alloy powder, or in Japanese Patent Application Laid-Open No. 4-297572, embrittlement is caused by using a sintered body in which Pt alone is present. It is stated that suppression is possible. In Japanese Patent Application Laid-Open No. 4-314855, Co is mainly used, Cr is 5 to 20 at%, and Pt is 1%.
It is disclosed that the hot workability is improved by reducing the amounts of S (sulfur) and C (carbon) in a composition in the range of 5 to 55 at%.

[0005] Further, the transition to CoCrPtTa-based multi-element alloys to which Ta is added for improving the properties of magnetic films is also progressing. For this reason, the plastic workability is further reduced, and in the melt casting method, an intermetallic compound is precipitated and casting segregation is likely to occur, and it is difficult to obtain a target having a uniform structure. The presence of such segregation causes variations in the magnetic flux density generated on the target surface when used in a normal magnetron sputtering method, so that sputtering is not performed uniformly and distribution of components of the Co alloy film occurs, This is a big problem for Co-based targets due to their different thicknesses.

[0006] Therefore, in order to homogenize the target structure, for example, Japanese Patent Application Laid-Open No. 5-86456 discloses a method in which a molten ingot is packed, heat-treated and then subjected to HIP (Hot Isostatic Pressing), followed by rolling. In 5-247638, Co is mainly used, Cr is 5 to 20 at%, Pt is 10 to 55 at%, Ni, Ta is 1 to 15 at
It discloses that forging, hot rolling, and cold rolling can be performed after melting and casting with an alloy containing 10 to 1500 ppm of a rare earth element to make the structure uniform and improve magnetic properties. Also, in Japanese Patent Application Laid-Open No. 5-247641, Co is mainly used and Cr or the like is 4 to 18 at.
It is stated that a target having a uniform structure can be obtained by sintering an alloy powder containing 0.5 to 16 at% of Pt, 0.1 to 8 at% of Nb, Ta and the like.

In Japanese Patent Application Laid-Open No. 8-17033, Co is mainly used and C is mainly used.
8 to 18 at% for r, etc., 0.5 to 16 at% for Pt, 0.1 to 8 at% for Nb, Ta, etc.
It is stated that a target having a uniform structure can be obtained by sintering the alloy powder containing 0.1%. In addition, Japanese Patent Application Laid-Open
No. 118818 is an alloy containing Ta, Mo, W, etc. in CoCrPt.
It is stated that hot rolling is performed after step rolling. In order to improve the magnetic properties of a target, Japanese Patent Application Laid-Open No. 8-27
No. 570 discloses that a Co-based alloy target is subjected to heat treatment after rolling or the like to change the crystal structure, and that magnetic properties can be improved by depositing an intermetallic compound layer at a crystal grain boundary.

[0008]

As described above, the Co-based target has been used as a ferromagnetic material so far as its structure and segregation.
Various studies have been made to obtain a desired target for forming a magnetic recording film by improving the magnetic characteristics. However, with the increase in recording density, Co-based alloys may be added with more Pt to improve film properties, for example, to increase coercive force, or may be added to the 4A, 5A, 6A, 7A group to reduce noise. As the amount of non-magnetic metal added increases, the target itself is changing from a magnetic substance to a non-magnetic substance. For this reason, a new problem has become apparent in the case of a non-magnetic target.

For example, when a substantially non-magnetic target is used, there have been problems that stable film characteristics cannot be obtained and the distribution of the film composition is deteriorated. An object of the present invention is to provide a Co-based target having a uniform film composition distribution and stably obtaining high film characteristics, a method of manufacturing the same, a sputtering apparatus, a magnetic recording film, and a magnetic recording apparatus.

[0010]

In order to solve the above-mentioned problems, the present inventors have investigated the relationship between the composition, structure, and magnetic properties of a target and the properties of a sputtered film. As a result, there is a correlation between the saturation magnetic flux density of the target and the film properties. When the target has a low saturation magnetic flux density, that is, when a substantially non-magnetic target is used, the stability of the film properties decreases or the film composition decreases. Was found to be less uniform. The inventors have found that, instead of simply adjusting the film to non-magnetic, leaving the magnetism improved the stability of the film and the uniformity of the composition, and reached the present invention.

That is, the present invention relates to a Co alloy mainly composed of Co and having a saturation magnetic flux density of less than 0.1 T as a melting material,
This is a Co alloy-based target whose saturation magnetic flux density is adjusted to 0.1 T or more. The melting material in the present invention means a material obtained by melting a target alloy composition.

In the present invention, more preferably, N
At least one selected from i and Pt contains a non-magnetic metal that reduces the saturation magnetic flux density. The above-mentioned amounts of Ni and Pt are preferably 3 to 30 at%, and more preferably, as the nonmagnetic metal, 18 at% or more of Cr is used as a nonmagnetic metal.
One or more selected from Nb are contained at 2 at% or more.

Further, in the production method of the present invention, when producing a target having a Co alloy composition mainly composed of Co and having a saturation magnetic flux density of less than 0.1 T as a melting material, the raw material is made of nonmagnetic powder or nonmagnetic alloy powder. And a magnetic substance powder, and sintering to adjust the saturation magnetic flux density to 0.1 T or more.

A sputtering apparatus according to the present invention is a sputtering apparatus for forming a Co-based magnetic thin film, comprising the above-described Co alloy-based target and a magnet for forming a leakage magnetic flux on the surface of the Co alloy-based target.

Further, a Co-based magnetic recording film having a coercive force of 160 kA / m or more and a residual magnetic flux density film thickness product of 130 G μm or less can be obtained by using the above-mentioned Co-based target.
Further, the present invention provides a magnetic recording apparatus including a magnetic recording medium on which the Co-based magnetic recording film is formed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the important features of the present invention is that, in order to obtain stability and uniformity of a film, a Co alloy-based target is used as a melting material in an alloy composition having a saturation magnetic flux density of less than 0.1 T. That is, the saturation magnetic flux density is set to 0.1 T or more. The cause of the correlation between the saturation magnetic flux density and the film properties is not clear, but if the saturation magnetic flux density of the target decreases, the leakage magnetic flux on the target surface will increase, and the plasma during sputtering will spread too much, causing the magnetic film on the substrate to become too thin. Influence on the growth of the film and the orientation of the film is considered as a factor.

Further, as the leakage magnetic flux becomes stronger, one direction in which Ar ions are incident on the target is given priority, which also affects the directionality of sputtered particles struck from the target, and the distribution of the film composition is reduced. It is considered that this is the cause of the decline. According to the study of the present inventors, it has been found that if the saturation magnetic flux density of the target is adjusted to 0.1 T or more, it is possible to stably obtain high film characteristics. It is a surprising fact that imparting magnetism to a target originally having a nonmagnetic composition improves the stability and uniformity of the film. In order to realize the Co alloy target of the present invention, for example, a magnetic substance may be left in a matrix in the target.

More specifically, as a raw material of the target, a nonmagnetic powder and a magnetic powder are mixed so as to have a predetermined composition, and sintering is performed to adjust the saturation magnetic flux density to 0.1 T or more. Can be obtained by: This is to adjust the magnetism by not allowing the magnetic powder to completely diffuse at the time of sintering but leaving the magnetic powder remaining. In the present invention, more preferably, the saturation magnetic flux density of the target is set to 0.2 to 1T.

In the present invention, one or more of Ni and Pt may be added, and a non-magnetic element for lowering the saturation magnetic flux density may be contained. These elements are added to the Co-based target to improve the film properties of the Co-based magnetic film. In particular, Pt and Ni are elements that alloy with Co to improve the coercive force. The non-magnetic element is added for noise reduction. Here, Ni and Pt are Co
In order to increase the coercive force, which is the magnetic characteristic of the alloy-based magnetic recording film, it is desirable to contain one or more of 3 to 30 at%.

Furthermore, non-magnetic elements such as Cr and T, which are added to improve the fineness of crystal grains and the segregation structure and crystal orientation for noise reduction desired for the magnetic recording film, are used.
Elements of groups 4A, 5A, 6A and 7A, such as a, Zr, Ti and Nb, are added. In particular, Cr segregates in the magnetic film, is highly effective in reducing noise, and greatly improves the characteristics of the magnetic film.
Furthermore, it is desirable to add 2 at% or more of other elements, Ta, Zr, Ti, and Nb, to reduce noise by accelerating the segregation of Cr, to reduce the crystal grain size and segregation structure,
Improve crystal orientation. Other non-magnetic elements Mn,
Since P, Al, and the like may sometimes improve the film characteristics, they can be added as a nonmagnetic element. As described above, various non-magnetic elements can be added depending on the required magnetic properties.

When manufacturing a target to which an element for improving the magnetic properties of Co, such as Ni or Pt, or an element for lowering the saturation magnetic flux density is manufactured, the saturation magnetic flux density according to the present invention is set to 0.1.
In order to adjust to 1T or more, as a raw material powder, a magnetic substance of Co, Ni or CoNi alloy, CoPt alloy, NiPt alloy, CoNiPt alloy, or a magnetic substance composed of an alloy of these magnetic substance elements and non-magnetic elements Or a magnetic powder material composed of a composite and a non-magnetic element, an alloy or compound of non-magnetic elements, or an alloy or compound of a magnetic element and a non-magnetic element, or a non-magnetic powder material composed of a simple substance or a composite Are mixed so as to have a predetermined composition, and then sintered, so that a Co alloy target having a saturation magnetic flux density of 0.1 T or more can be manufactured. Sintering can be performed not only by hot isostatic pressing (HIP method) but also by hot pressing or the like.

The Co alloy target of the present invention
It can be incorporated in a sputtering apparatus having a magnet that forms a leakage magnetic flux on the surface of an o-alloy-based target and used. Further, when a Co-based magnetic recording film is formed using the target of the present invention, the leakage magnetic flux on the target surface is reduced by 300%.
It is desirable to set it to 800G. If the leakage magnetic flux is less than 300G, it is difficult to maintain stable plasma during sputtering, and it may not be possible to form a stable film.If it exceeds 800G, the plasma spreads to the substrate on which the film is formed, and the film is formed. This is because growth and crystal orientation at the time are easily affected.

When a Co-based magnetic recording film is formed using the target of the present invention, the voltage is preferably set to 300 to 700 V when applied to the target during sputtering. When the voltage applied to the target is less than 300 V, the incident energy of argon ions on the target during sputtering is insufficient, and the amount of recoil particles incident on the magnetic recording film is insufficient, and the magnetic characteristics of the magnetic recording film are reduced. If the voltage is 700 V or more, plasma may not be stable during sputtering, and stable film formation may not be performed.

In the Co-based magnetic recording film of the present invention, the coercive force required for the magnetic recording medium is 160 kA / m or more, and the residual magnetic flux density film thickness product is 130 G μm or less, when the composition is such that the saturation magnetic flux density of the molten material is 0.1 T or less. This is a Co-based magnetic recording film having magnetic characteristics, and the magnetic characteristics can be stably obtained by using the Co-based target as the magnetic recording film to obtain a Co-based magnetic recording film having the above magnetic characteristics. By providing it as a medium, a magnetic recording device with a high recording density can be stably obtained.

In the Co alloy target of the present invention,
It is desirable that gas components such as carbon and oxygen contained in the film are small in order to affect the properties of the film, for example, coercive force and a decrease in the squareness ratio.In the present production method, carbon is 50 ppm or less, preferably 10 ppm or less, and oxygen 300 ppm or less. Preferably it is 100 ppm or less. The target of the present invention preferably has a high density from the viewpoint of preventing abnormal discharge, and more preferably has a relative density of 97% or more with respect to the theoretical density calculated from the element alone.

[0026]

[Example] (Example 1) 70Co20Cr4Ta6Pt and 68Co23Cr2Ta7
Co and C are magnetic powders so that the atomic% composition of Pt is obtained.
oPt, CoCr, CoCrTa, CoCrTaPt and non-magnetic powder Cr, Pt, T
a, CoCr, CoCrTa, and CoCrTaPt were sieved to 32 mesh or less and packed in Fe cans in various combinations shown in Table 1.
After that, heat deaeration treatment and vacuum sealing
(Hot isostatic press) and kept at 1000 ° C. and a pressure of 127 MPa for 3 hours for sintering. After sintering, the Fe can was removed, and a sample for measuring magnetic properties and a target having a diameter of 150 mm and a thickness of 5 mm were manufactured by machining. As a comparative material, it was targeted by a melt-casting method. In addition, a prealloyed atomized powder having the above composition was sintered in the same manner to produce a target.

The saturation magnetic flux density of the sample for measuring magnetic properties was measured using a VSM (oscillating magnetic force magnetometer). The prepared target was mounted on a magnetron sputtering device with a magnet on the back of the target, and NiP plating with a surface roughness (Ra) of 2 nm was applied under the following sputtering conditions. A 25 nm magnetic recording medium was formed on an Al substrate (commonly referred to as a 3.5 "NiP plated substrate), and the film characteristic distribution in the substrate and the dispersion of the film characteristics when 100 sheets were continuously sputtered were measured. Show.

[0028]

[Table 1]

The composition shown in Table 1 was dissolved as shown in Table 1.
The melting materials manufactured by the casting method, Samples 13 and 14, can obtain only a saturation magnetic flux density of less than 0.1 T, and have a composition that is substantially non-magnetic. In the case of sintering the powder obtained by the atomizing method, which includes a step of alloying by melting, the samples 15 and 16 also require 0.1
Only a saturation magnetic flux density less than T is obtained, and it is substantially non-magnetic. As shown in Table 1, samples 1 to 12, which are targets of the present invention obtained by sintering a magnetic material and a non-magnetic material and adjusting the saturation magnetic flux density to 0.1 T or more, are different from the targets of the comparative example described above. It can be seen that the variation in the coercive force in the plane is small and the variation between the substrates to be manufactured is also small.

A Co-based magnetic recording film having a high coercive force of 170 kA / m or more and a residual magnetic flux density film thickness of 130 Gμm or less can be obtained by using the target of the present invention. By using these magnetic recording films for a magnetic disk, it is possible to stably manufacture a magnetic recording apparatus using an MR head, a GMR head, or the like that is compatible with current high-density recording.

Comparative Example Using a 75Co16Cr4Ta5Pt composition,
In the same manner as in Example 1, a sample for measuring magnetic properties and a target were prepared, and the magnetic properties and the film properties were measured. Sample 26 in Table 2
As shown in the figure, this composition is magnetic (Bs ≧ 0.1
T). As shown in the other samples in Table 2, the target having a composition having a slight magnetic property originally has a small variation in the coercive force in the plane and a small variation between the media to be manufactured. It can be seen that even if magnetism is provided, the effect is small.

[0032]

[Table 2]

(Example 2) Composition 70Co20Cr4Ta6 of Example 1
Pt sample Nos. 1, 2, 4 and 68Co16Cr3Ta5Pt sample 7,
For 8 and 10, targets were prepared in the same manner as in Example 1 and the sintering temperature was changed at that time to investigate. The results are shown in Tables 3 and 4, respectively. The temperature and pressure under the HIP conditions are as follows: 700 ° C-152MPa, 800 ° C-152MPa, 900 ° C-152MPa, 100
0 ℃ -127MPa, 1100 ℃ -127MPa, 1200 ℃ -127MPa, 1300
The operation was carried out under seven conditions of -127 MPa, and the holding time was 3 hours.

[0034]

[Table 3]

[0035]

[Table 4]

As shown in Tables 3 and 4, the sintering temperature was
A magnetic recording film having a uniform film characteristic distribution in the range of 700 to 1100 ° C. is obtained. At 1200 ° C. or higher, alloying due to powder diffusion is promoted to lower the saturation magnetic flux density, and when it is less than 0.1 T, the film characteristic distribution becomes non-uniform. Also 70
At 0 ° C., the magnetic properties were uniform, but the density of the target was low, and it was confirmed that a problem that foreign matter was easily generated occurred. Therefore, the sintering temperature at which a density of 97% or more was obtained was as follows. 800-1200 ° C is preferred, more preferably 900
~ 1100 ° C.

Example 3 Next, various compositions were examined. 57Co20Ni18Cr5Ta, 64Co24Cr12Pt, 60Co22Cr2Ta
16Pt, 62Co24Cr12Pt2Zr, 65Co23Cr5Ti7Pt, 55Co20Ni3Pt
C, so that the composition of 18Cr4Ta, 40Co25Ni9Pt23Cr3Ta
o, sieve magnetic powder and non-magnetic powder of CoNi, CoPt, CoNiCr, CoPtCr, CoCr, CoCrTa to 32 mesh or less, Table 5
After mixing in various combinations shown in, packed in cans made of Fe,
Sintering was performed using HIP (Hot Isostatic Press). The temperature-pressure under the HIP condition was set at 1000 ° C.-127 MPa, and the holding time was set at 3 hours.

In the same manner as in Example 1, the can was removed after sintering, and a sample for measuring magnetic properties and a target having a thickness of 5 mm and a diameter of 150 mm were manufactured. As a comparative material, a melt-casting method and an atomized powder having the above composition were manufactured using the same sintered sample,
Similarly, a sample for measuring magnetic properties and a target were prepared. A target having the above composition was prepared. Sample for magnetic property measurement
The saturation magnetic flux density was measured using a VSM (oscillating magnetometer). The prepared target was attached to a sputtering apparatus in the same manner as in Example 1, and the surface roughness (R) was set under the following sputtering conditions.
a) A 25nm magnetic recording medium is formed on a 95mm diameter, 0.8mm thick Al substrate (commonly called 3.5 "NiP plated substrate) with 2nm textured NiP plating. The dispersion of the film characteristics was measured when 100 sheets were sputtered, and the results are shown in Table 5.

[0039]

[Table 5]

[0040] As described above, even in a system to which various additional elements are added, when the saturation magnetic flux density is 0.1 T or less, fluctuations in film characteristics within the substrate and between the substrates increase, and it is difficult to obtain a stable magnetic recording medium. It is understood that stable film characteristics can be obtained by using the target of the present invention.

As described above, Ni, Cr, Ta, Z
Even when using the target of the present invention to which elements of the 4A, 5A, and 6A groups such as r, Ti, and Nb are added, the magnetic characteristics are still 17
A Co-based magnetic recording film having a high coercive force of 0 kA / m or more and a residual magnetic flux density film thickness of 130 Gμm or less can be obtained. By using these magnetic recording films for a magnetic disk, it becomes possible to stably manufacture a magnetic recording device using an MR head, a GMR head, or the like that is compatible with current high-density recording.

[0042]

The Co-based target of the present invention, as a target required for a future high-density recording medium, improves the characteristics of a magnetic recording film in a composition which is substantially non-magnetic, and furthermore, the characteristics of the characteristics are not improved. It is possible to obtain a small number of magnetic films. Therefore, the target of the present invention is a sputtering apparatus used when forming a magnetic recording film, a magnetic recording film,
The characteristics of a magnetic recording device using the magnetic recording film can be remarkably improved, and this is an indispensable technology for obtaining a recording device in the information society in the future.

Continued on the front page F term (reference) 4K018 AA02 AA08 AA10 AA40 BB06 BC12 DA32 EA16 FA06 KA29 KA42 4K029 AA02 AA24 BA24 BC06 BD11 CA05 DC04 DC09 DC39 FA07 5D006 BB01 BB07 EA03 FA09 5E049 AA04 AA09 GC06

Claims (7)

[Claims] 1. A Co alloy mainly composed of Co and having a saturation magnetic flux density of less than 0.1 T as a melting material, the saturation magnetic flux density of which is less than 0.1 T.
A Co alloy target adjusted to 0.1 T or more. 2. The Co alloy-based target according to claim 1, comprising one or more selected from Ni and Pt and a nonmagnetic metal. 3. A non-magnetic metal, which is mainly composed of Co and contains at least one selected from Ni and Pt in an amount of 3 to 30 at%.
2. The Co alloy-based target according to claim 1, wherein the target comprises 18 at% or more and at least 2 at% of at least one selected from Ta, Zr, Ti and Nb. 4. When producing a target having an alloy composition mainly composed of Co and having a saturation magnetic flux density of less than 0.1 T as a melting material, the raw material is mixed with a nonmagnetic powder and a magnetic powder,
A method for producing a Co alloy-based target, wherein the saturation magnetic flux density is adjusted to 0.1 T or more by sintering. 5. A sputtering apparatus for forming a Co-based magnetic thin film, comprising: the Co alloy-based target according to claim 1; and a magnet for forming a leakage magnetic flux on a surface of the Co alloy-based target. A sputtering apparatus. 6. C according to claim 1, wherein
Coercive force 160kA / m formed using o-alloy target
As described above, a Co alloy-based magnetic recording film having a characteristic of a residual magnetic flux density film thickness product of 130 Gm or less. 7. A magnetic recording apparatus comprising a medium on which the magnetic recording film according to claim 6 is formed.