JP2857729B2 - Target member for spatter and method for producing the same - Google Patents

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 sputter film on a base film for making a magnetic recording layer (magnetic film) in-plane anisotropic in a metal thin film type magnetic recording medium and a method of manufacturing the same.

[0002]

2. Description of the Related Art A metal thin film type magnetic recording medium is a recording medium in which a thin film of a Co-based ferromagnetic alloy is formed on a non-magnetic substrate as a magnetic recording layer (magnetic film). A base film for making the magnetic film in-plane anisotropic is provided on the substrate, and the magnetic film has a layered structure formed on the film surface by epitaxial growth. The laminated film is formed by a sputter method. CoCr, CoCrNi, or the like is used as a Co-based alloy for forming the magnetic film. CoCrTa, CoCrNi containing an appropriate amount of Ta has recently been used for the purpose of reducing recording / reproducing noise and improving recording density.
A magnetic film made of Ta or the like is often formed. On the other hand, Cr films have been used exclusively as underlayers for introducing in-plane magnetic anisotropy into these magnetic films,
As an improvement, it has been proposed to form a Cr film containing a certain amount of elements such as Ag and Si (Japanese Patent Laid-Open No.
-12813, JP-A-4-60916).

[0003]

The demand for high-density recording in the field of magnetic recording has been increasing more and more, and in order to meet this demand, magnetic and electrical characteristics have been improved, and in particular, higher coercive force and reduced recording / reproducing noise have been further required. It is required to proceed. In order to improve the magnetic and electrical characteristics of an in-plane magnetization type recording medium having a layer structure in which a magnetic film is laminated on an underlayer, it is necessary to improve the consistency of the lamination interface between the magnetic film and the underlayer to improve the magnetic properties. It is necessary to facilitate the epitaxial growth of the film, to reduce interface mismatching and crystal distortion, and to form a crystal grain structure in the magnetic film in which the magnetization transition width is small. The present invention provides a target member for forming a sputter film on a base film capable of forming such a laminated magnetic film, and a method for manufacturing the same.

[0004]

The target member for a spatter according to the present invention is a chemical composition represented by the formula: Cr _100-X B _X [wherein X representing atomic% is 1 to 10] ... [I] And a sintered body having a relative density of 98% or more. The target member of the present invention can be manufactured by a hot isostatic pressing sintering method using a powder adjusted to the above chemical composition as a sintering raw material.

[0005]

The undercoat film formed by sputtering using the target member of the present invention has excellent consistency with the Co-based alloy magnetic film laminated thereon due to the change in the crystal lattice constant of Cr due to the inclusion of B. In addition, the epitaxial growth of the magnetic film becomes smoother, thereby reducing interface mis-matching, improving the orientation of the magnetic film with the C axis in the in-plane direction, and reducing crystal distortion. The underlayer film formed using the target member of the present invention has a B-containing effect of C
The crystal grains of r are fine and their columnar crystals are clarified, and this change in crystal structure promotes clarification of the grain boundaries and isolation of magnetic domains of the magnetic film alloy that grows epitaxially on the film surface, The magnetization transition width decreases.

Hereinafter, the present invention will be described in detail. The B content of the target member of the present invention is 1 to 10 atomic%. The reason why the lower limit of 1 atomic% is set is that if the B content is less than that, the effect of improving the coercive force and the recording / reproducing characteristics of the magnetic film laminated on the film surface is insufficient. The upper limit of atomic% is that a large amount of B
This is because the inclusion of inevitably reduces the coercive force of the magnetic film and lowers the recording / reproducing characteristics. A more preferable B content is about 2 to 8 atomic%.

The reason why the target member of the present invention is manufactured as a sintered body is to prevent segregation of B and to improve the homogeneity and denseness of the composition over the entire thickness of the target member. That's why. That is, B is hardly dissolved in Cr, and is hard and brittle Cr-B intermetallic compound (Cr
B, CrB ₂ , Cr ₃ B _2, etc.) can be easily produced. Therefore, when a melting / casting process, which is a general method for producing a target member, is applied to the production of the target member of the present invention, an ingot is obtained. Indicates that significant segregation of B and Cr-
Since the B has a cast structure accompanied by local crystallization and uneven distribution of the intermetallic compound, and its ingot is extremely brittle and easily cracked, it is impossible to apply plastic working to impart the necessary high density to the target member. It is possible. Therefore, in the present invention, by manufacturing this as a sintered body, uniformity and high density desired as a target member are secured. The reason why the compact density of the sintered body is set to 98% or more in relative density is that if the compactness of the sintered body is low, the amount of gas contained in the sintered body is large, and the gas from the target during sputtering is large. This is because abnormal discharge is likely to occur due to the release, the soundness of the underlying film formed on the substrate is impaired, and the improvement effect of the magnetic film cannot be sufficiently exhibited, and the relative density is 98% or more. As a result, gas emission during sputtering and the above-mentioned adverse effects associated therewith are prevented.

[0008] The sintered body, which is the target member of the present invention, comprises:
It is manufactured by subjecting a powder adjusted to the chemical composition represented by the formula [I] to a raw material and performing hot isostatic pressing sintering. As the sintering raw material powder, a B-containing Cr powder, a mixed powder of a Cr powder and a B powder, or a Cr powder and a B-containing Cr powder or a Cr-B intermetallic compound (CrB,
A mixed powder with a powder of CrB ₂ , Cr ₃ B ₂ , Cr ₃ B ₄ or the like can be used. The particle size of the sintering raw material powder is, for example, about 50 to 400 μm for the B-containing Cr powder, and about 50 to 400 μm for the mixed powder.
It is appropriate that the B powder and the Cr-B compound powder to be blended with the above are about 5 to 250 μm. Even when the Cr-B compound is used as the B source, the sintering reaction is performed under the uniform action of the high pressing force by the hot isostatic pressing sintering method while using the fine powder as described above. By doing so, it is possible to secure good homogeneity of the sintered body required as a target member.

The above-mentioned sintering raw material powder is filled in a capsule, degassed and sealed, and then subjected to sintering. The capsule material is
Mild steel, stainless steel, etc. can be used as appropriate. The sealing of the capsule is preferably performed under a vacuum of about 0.1 mmHg or less so as not to hinder high density during the sintering reaction process. For the pressure sintering treatment, a hot isostatic pressing sintering method capable of completing the sintering reaction under a uniform action of high pressure is suitable. The sintering process is performed at a sintering temperature of about 1000 ° C. or more and a pressing force of about 1000 kgf / in order to impart high density with a relative density of 98.0% or more to the formed sintered body.
cm ² or more, and the treatment time is preferably about 1 Hr or more. The higher the sintering temperature, the more the sintering reaction is promoted. However, if the sintering temperature is too high, a liquid phase is generated and the segregation of B is caused, thereby impairing the homogeneity of the sintered body.
High temperatures above are to be avoided. The pressing force and the holding time are sufficient up to 1300 kgf / cm ² and 4 hr, respectively.

[0010] The sintered body obtained through the above steps is subjected to appropriate machining to be finished into a target member having a predetermined shape. Also, the sintered body can be subjected to plastic working such as hot or cold forging and rolling, unlike the method of melting / casting, and therefore, if necessary, the plasticity is further increased in order to further increase its denseness. It can be formed into a predetermined plate shape by processing.

The manufacture of a magnetic recording medium using the target member of the present invention as a material for forming a base film may be carried out according to a conventional method. For example, if we talk about magnetic disks,
An aluminum alloy plate or the like is used as a substrate, and a hard Ni-P plating film (film thickness: for example, 15
After applying a texturing treatment to the surface of the plating film, a B-containing Cr film having an appropriate thickness (for example, 50 μm) is used as an underlayer of the magnetic film by using the target member of the present invention.
Then, a magnetic film (thickness is, for example, 500 to 1000) is formed on the film surface. In the step of forming the underlayer by sputtering, or the underlayer and the subsequent magnetic film, the coercive force of the magnetic film,
For the purpose of controlling the recording / reproducing characteristics, a bias sputter that applies a negative potential (for example, −100 to −400 V) to the substrate and performs spattering is applied as necessary. A film having lubricity and wear resistance, for example, a carbonaceous film (thickness: for example, 150 to 600 °) is provided on the film surface of the magnetic film as a protective film for preventing its wear and damage, if desired.
Is formed according to a conventional method.

[0012]

【Example】

[I] Manufacture of target member Cr powder (particle diameter of 350 μm or less) and CrB powder (particle diameter of 10 μm or less) are blended so as to have a predetermined stoichiometric chemical composition. ) To prepare a sintering raw material powder for 2 hours. The above powder mixture was filled in a mild steel capsule container, and the degree of vacuum was 0.08 mmHg.
And then hot isostatic pressing sintering (HI
P), temperature 1250 ° C, pressure 1100kgf /
The sintering was performed under heating and pressure of 2 cm ² for 2 hours. After sintering, the capsule container was removed by machining to take out a plate-like sintered body (thickness: 40 mm), which was then machined to obtain a target member (thickness: 4 mm). Table 1 shows the chemical composition of the test target member. Nos. 1 to 3 are invention examples, and No. 4 is a comparative example corresponding to a conventional material containing no B (sintering conditions are the same as the invention examples). The relative density of the sintered body of each target member is 99% or more.

[II] Production of magnetic recording medium A base film (film thickness: 1400 °) is formed on an aluminum alloy substrate (a 20 μm-thick Ni—P alloy electroless plating film is formed on the surface) by a DC magnetron sputtering method. Co ₈₆ Cr ₁₂ Ta ₂ alloy film (film thickness: 600)
Å) and a carbonaceous protective film (graphite carbon film, 250 Å) were laminated to form a test magnetic disk (sputter atmosphere: Ar gas, 5 × 10 ⁻³ Torr).
r, substrate temperature: 250 ° C.).

(1) Measurement of Coercive Force (Hc) Table 2 shows the results of measurement of the coercive force Hc (Oe) of the magnetic disk on which the underlayer was formed using the target members No. 1 to No. 4. I have. In the table, column A shows a magnetic disk on which an underlayer film and a magnetic film are formed using a bias sputter (bias potential: -300 V), and column B shows a bias sputter (bias potential: -300 V) only when the sputter of the underlayer is formed. It is a measurement result about the magnetic disk which was made. 1 and 2 show the coercive force (H
3 is a diagram illustrating the relationship between c) and the B content (at%).

(2) Recording / Reproduction Test Table 3 shows the target members No. 2 (inventive example) and No. 4
A recording / reproducing test result is shown for a magnetic disk on which a base film is formed using (Comparative Example). However, the test magnetic disk in column C of the table is a magnetic disk (coercive force Hc: 1400 Oe, Br · δ: 4) formed by a sputter that does not apply a bias potential to both the base film and the magnetic film.
00 G · μm), and the test magnetic disks shown in the second column of the table are magnetic disks (coercive force H) in which only a magnetic film sputter film is formed as a bias spatter (bias potential: -250 V).
c: 1500 Oe, Br · δ: 400 G · μm). In the table, HF-TAA is the high-frequency track average output (μ
V), Res are the resolution (%), O / W is the overwrite (db), and PW50 is the half width (nsec) of the modulated wave.

As shown in the above tables, the magnetic recording medium in which the underlayer was spattered using the B-containing Cr target member of the present invention was a magnetic recording medium using a conventional Cr target member containing no B. Higher coercive force (H
c), and has improved recording / reproducing characteristics as apparent from comparison of magnetic disks having the same level of coercive force (Hc) and Br · δ (product of residual magnetic flux density and film thickness). doing.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

According to the present invention, the underlayer film for making the magnetic recording layer (magnetic film) of the metal thin film type magnetic recording medium in-plane anisotropic is formed by sputtering using the target member of the present invention. The coercive force of the film, the recording / reproducing noise magnetism, etc. are enhanced, and higher density recording becomes possible as an effect of improving the magnetic and electrical characteristics.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the B content of a base film and the coercive force of a magnetic film.

FIG. 2 is a graph showing the relationship between the B content of a base film and the coercive force of a magnetic film.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-183463 (JP, A) JP-A-3-138365 (JP, A) JP-A-4-60916 (JP, A) JP-A-3- 12813 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 14/34 C22C 1/04

Claims (2)

(57) [Claims] 1. A shall apply in Tagetsuto member for sputter depositing a base film of the magnetic recording layer in the metal thin film type magnetic recording medium, in the formula Cr _100-X B _X [wherein, the X representing the atomic% 1 And a sintered body having a relative density of 98% or more. 2. Cr _100-X B _X [wherein X represents atomic%.
Is 1 to 10]. A powder adjusted to the chemical composition represented by the formula is filled in a metal container, and after degassing and sealing, hot isostatic pressing sintering is performed. A method for producing the target member according to the above.