JPH0641734A - Target member and its production - Google Patents

Abstract

PURPOSE:To improve a target member for forming a magnetic recording layer (magnetic film) having improved magnetic characteristics fit for high density recording by a sputtering method. CONSTITUTION:This target member is a sintered compact consisting of, by atom, 6-17% Cr, <38%, in total, of 0.3-36% Ni and 0.5-8% Ta and the balance essentially Co and having >=98% relative density. This target member is produced by filling a capsule with atomized powder having <=22 mesh particle diameter, hermetically sealing the capsule in vacuum of <=0.1mmHg and carrying out sintering by hot isostatic pressing at 800-1,250 deg.C under 500-2,000kgf/cm<2> for 0.5-4hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target member for forming a magnetic recording layer of a magnetic recording medium by a sputtering method, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A magnetic recording medium such as a magnetic disk or a magnetic tape is a metal thin film type recording medium having a magnetic recording layer (magnetic film) formed of a ferromagnetic alloy from the viewpoint of high density recording property. Type magnetic recording media have become the mainstream. Co-Ni, Co-C is used as a target member for forming the magnetic recording layer on the non-magnetic substrate by the sputtering method.
r, Co-Ni-Cr alloys have been used.

The demand for high-density recording in the field of magnetic recording is increasing more and more, and higher coercive force and reduction of noise level are required.
A magnetic film formed using an o-Cr, Co-Ni-Cr alloy or the like as a target member has a limited improvement effect.

Various proposals have been made to improve the target member to meet the demand for high density recording.
For example, JP-A-1-133217 discloses that a certain amount of T
It is described that a high coercive force and a noise reducing effect are obtained by forming a magnetic film using a Co-Cr-Ta alloy containing a as a target member, and JP-A-3-138365 discloses that Co-Cr-Ta alloy. As an improvement of the target member for improving the homogeneity of the magnetic properties of the alloy magnetic film,
It is described that a homogeneous dense sintered body produced by pressure-sintering a fine rapidly solidified powder of a Co-Cr-Ta alloy is used as a target member. Besides, by forming a magnetic film by using Co-Cr-B and Co-Cr-Ni-B alloys containing a certain amount of B added as a target, and by bias bias sputtering for applying a negative voltage to the substrate in the sputtering deposition. It has also been proposed to increase the coercive force of the magnetic film (Japanese Patent Laid-Open No. 3-49021 and Japanese Patent Laid-Open No. 3-54723).
Issue).

[0005]

SUMMARY OF THE INVENTION The present invention provides a target member having a novel alloy composition for forming a magnetic film having improved magnetic properties suitable for high density recording of a magnetic recording medium, and a method of manufacturing the same. To do.

[0006]

Means and Actions for Solving the Problems The target member of the present invention is, in atomic%, Cr: 6 to 17%, Ni:
0.3-36%, Ta: 0.5-8% (however, Ni and T
The total amount of a does not exceed 38%), the balance is substantially Co and the relative density is 98% or more. The target member of the present invention is manufactured by using hot atomizing under pressure and sintering using fine atomized powder having the above composition and having a particle size of 22 mesh or less and rapidly solidified and solidified.

The present invention will be described in detail below. The target member of the present invention is formed as a sintered body in order to prevent uneven distribution of constituent elements within the thickness of the target member and to obtain homogeneity of composition throughout the plate thickness direction. Is. Normally, the target member is manufactured as an ingot by melting / casting, and through a hot or cold plastic working (forging, rolling, etc.) step for densifying the ingot. The target alloy having the above composition has a relatively low solid solution limit of Ta, and in addition, a deviation from the equilibrium state occurs in the casting process in industrial production. Inevitably accompanies local crystallization and uneven distribution of the compound. The inhomogeneity of the composition cannot be sufficiently eliminated even by performing hot and cold plastic working. When a target member having such a non-uniform composition is used, the composition of the magnetic film formed by vapor deposition on the substrate changes with the progress of sputtering and it is impossible to secure the desired magnetic characteristics. . Therefore, the present invention, by forming the target member as a sintered body using a homogenous fine powder of composition as a raw material,
The homogeneity of the composition inside the wall thickness of the target member is ensured, and at the same time, the target member is made highly dense.

The target member of the present invention comprises Cr: 6 to 1
7%, Ni: 0.3 to 36%, and Ta: 0.5 to 8
% (However, the total amount of Ni and Ta is 38% or less) and the balance substantially consisting of Co is because the coercive force (Hc) of 1300 Oe or more is exhibited in this composition range, and high density recording is achieved. This is because the improved magnetic properties that can be obtained are obtained, the weather resistance is good, and the stability required for the recording layer is secured. The upper limit of the total amount of Ni and Ta is set to 38% because if it exceeds the limit, the coercive force will decrease. The content of Ni and Ta is preferably N
i: 0.5% or more, Ta: 1% or more.

The density of the target of the present invention is set to 98% or more in terms of relative density because when the density of the sintered body is low, the amount of gas contained in the sintered body is large and the target during sputtering is large. This is because abnormal discharge is likely to occur due to gas release from the substrate, the homogeneity of the magnetic film formed on the substrate is impaired, and the effect of improving the magnetic properties cannot be sufficiently exhibited. As 98% or more,
It prevents the gas emission during spattering and the above-mentioned adverse effects.

The Co-based alloy powder having the above composition used as a raw material for sintering the target member of the present invention is required to be homogeneous without segregation of constituent elements. This is because the nonuniformity of the composition of the raw material powder is a cause of impairing the homogeneity of the composition of the sintered body. Therefore, in the present invention, atomized powder is used as the raw material powder. The fine powder obtained by performing sufficient rapid cooling and solidification at the time of atomizing the molten alloy in the atomizing method has a rapid cooling effect, in which Ta having a low solid solubility limit is uniformly solid-dissolved and those compounds are crystallized. However, it has a highly homogeneous structure that is finely dispersed and crystallized. The atomized alloy powder is limited to a fine powder having a particle size of 22 mesh or less in order to secure the homogeneity of the powder composition due to a sufficient quenching effect. As the atomized powder, gas atomized powder, water atomized powder, vacuum atomized powder, or the like can be appropriately used.

The atomized powder is filled in a capsule container, hermetically sealed by deaeration, and then subjected to pressure sintering treatment. The material of the container may be selected such as mild steel and stainless steel. The reason why the powder filled in the container is hermetically sealed under a vacuum of 0.1 mmHg or less is a harmful effect due to nitrogen and oxygen remaining in the sintered body (which causes abnormal discharge in sputtering). This is to prevent

The hot isostatic pressing method (H
The reason why the IP sintering method is applied is to form a sintered body excellent in homogeneity and compactness by a sintering reaction that occurs under the uniform action of a high pressure. The sintering process has a temperature of 8
00 to 1250 ° C, applied pressure: 500 to 2000 Kgf /
cm ^2, retention time: successfully is often achieved under the conditions of 0.5~4Hr. Temperature: 800 ° C or higher, Pressurization force: 500 Kg
The reason for setting f / cm ² or more and holding time: 0.5 Hr or more is that it is difficult or impossible to secure the denseness of relative density of 98% or more under the processing conditions less than that, on the other hand, The upper limit of the treatment temperature is defined as 1250 ° C. When the temperature exceeds the upper limit, the liquid phase is generated and the segregation of Ta and the like occurs, and as a result, the effect of using the fine atomized powder is lost. This is because it becomes impossible to ensure the homogeneity of the obtained sintered body. Further, the upper limit of the pressing force is set to 2000 Kgf / cm ² and the upper limit of the holding time is set to 4 Hr, because there is no benefit obtained by applying the pressing force and time longer than that.

The sintered body obtained through the above steps is subjected to appropriate machining to finish it into a target member having a predetermined shape. In addition, unlike the melting and casting method, the sintered body can be plastically worked by hot or cold forging, rolling, etc. Therefore, if desired, plasticity can be increased to further increase its denseness. It can also be processed and formed into a predetermined plate shape.

The magnetic recording medium using the target member of the present invention as a magnetic film material may be manufactured by a conventional method. For example, referring to a magnetic disk for in-plane recording, an aluminum alloy plate or the like is used as a substrate, and a hard Ni-P plating film (film thickness: for example, 15 to 2) is formed on the surface by electroless plating.
5 μm), and the plating film surface is subjected to a texturing treatment, and then a Cr film is formed to an appropriate film thickness (for example, 500 to 3000 Å) as a base layer for giving in-plane anisotropy to the magnetic film. Using the target member of the present invention, a magnetic film (having a film thickness of, for example, 500 to 1000) is formed on the Cr film surface.
Å) form. In the process of forming the sputtering film of the magnetic film, a negative voltage (about -40V or more, for example, -4V) is applied to the substrate side.
When a bias sputtering for applying 0 to −250 V) is applied, it is possible to impart a higher coercive force to the magnetic film as an effect thereof. On the film surface of the magnetic film, a film having lubricity and wear resistance, such as a carbonaceous film (film thickness: for example, 150 to 600Å), is optionally provided as a protective film for preventing abrasion and damage. ) Is formed according to a conventional method.

[0015]

【Example】

[I] Production of target member A gas atomized powder of a Co-based alloy having a predetermined chemical composition is classified, and a fine powder of 22 mesh Yuanda is used as a sintering raw material. The atomized powder was filled in a mild steel capsule container, vacuum-sealed at a vacuum degree of 0.08 mmHg, and subjected to hot isostatic pressing (HIP) (Table 1). After sintering, the capsule container was removed by machining to take out a plate-shaped sintered body (plate thickness: 40 mm), and this was machined to finish into a plurality of target members (plate thickness: 4 mm).

Table 1 shows the relative densities of the test target members and the chemical composition analysis values of the surface and the center of the plate thickness. In the table,
T1 to T4 are the sintered body targets of the invention examples, and T5 to T7 are comparative examples. The target members of Comparative Examples T5 and T6 are sintered bodies manufactured by the same HIP treatment as the invention examples, but the former lacks Ta content, and the latter has an excessive Ni content and Ni and Ta content. In this example, the total amount deviates from the upper limit. Comparative Example T7 is an example manufactured by melt casting as a slab (plate thickness 40 mm) (however, the alloy composition satisfies the requirements of the present invention). The test target member T7 manufactured as a slab has a large difference in the Ta content between the surface and the central portion of the plate thickness, whereas it is formed as a sintered body by HIP treatment using fine atomized alloy powder. Test target members T1 to T
The segregation in the plate thickness direction of No. 4 is slight and has excellent homogeneity. The test material T7 formed as a slab was cracked during the casting and hot rolling steps, and could not be formed into a predetermined shape as a target member.

[II] Production of magnetic disk Aluminum alloy substrate (Ni-P having a film thickness of 20 μm on the surface)
Alloy electroless plating film formation) using DC magnetron sputtering method, sputtering atmosphere: 5 × 10 ^-3 To
Under a sputtering condition of rrAr gas, substrate temperature: 250 ° C., substrate bias voltage: −150 V, a Cr film (film thickness: 1
000Å), a magnetic film (film thickness: 600Å), and a carbonaceous film (film thickness: 250Å) were laminated in this order to manufacture an in-plane anisotropic magnetic disk. The test target members T1 to T6 described above were used for forming the magnetic film as a sputtering film. Table 2 shows the measurement results of the target member used for forming the sputtering film of the magnetic film, the sputtering layer position thereof, and the magnetic characteristics of each magnetic disk under test.

As shown in Table 2, each of the magnetic disks D1 to D8 having a magnetic film formed by using the target members T1 to T4 of the present invention has a high coercive force (Hc) of about 1300 Oe or more. In addition, the value of the coercive force squareness ratio S ^* is also at a relatively low level, and the magnetic disks D9 and D10 using the target member 5 (not containing Ta) and the magnetic disk using the target member 6 (excessive amount of Ni) are used. The difference from the disks D11 and D12 is obvious. The coercive force squareness ratio S ^* is a characteristic value that is related to recording medium noise, and the lower the value, the smaller the medium noise. By using the target member of the present invention, It can be seen that a recording medium having magnetic characteristics suitable for density recording can be obtained. Also, using the same target member,
As can be seen from the comparison between the magnetic disk formed by sputtering the surface layer to form the magnetic film and the magnetic disk formed by forming the magnetic film by sputtering the plate thickness center layer, the characteristics of the magnetic film with the progress of the sputtering. Is small, and a magnetic film having stable magnetic characteristics can be formed from the beginning of use of the target member to the end of its life.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

By using the target member of the present invention, a magnetic film having magnetic characteristics suitable for high density recording can be formed. Since the target member has good homogeneity with little composition variation in the plate thickness direction,
From the beginning of use of the target member to the end of its life, the magnetic film formed by the sputtering has a predetermined alloy composition and improved constant magnetic characteristics, and is excellent in reliability as a magnetic recording layer. ing.

Claims (2)

[Claims] 1. Cr: 6 to 17%, Ni: in atomic%.
0.3-36%, Ta: 0.5-8% (however, Ni and T
The total amount of a does not exceed 38%), the balance substantially consisting of Co, and the relative density: a sintered body having a relative density of 98% or more. 2. In atomic%, Cr: 6 to 17%, Ni:
0.3-36%, Ta: 0.5-8% (however, Ni and T
(The total amount of a does not exceed 38%), the balance is substantially Co, and the atomized alloy powder having a particle size of 22 mesh or less is filled in a metal container, deaerated and sealed, and then hot isostatic pressing is performed. The method of manufacturing a target member according to claim 1, wherein the target member is bonded.