JP2000017433A - B2 rule lattice intermetallic compound target and magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermetallic compd. target of high deflective strength which is a B2 rule lattice intermetallic compd. and a magnetic recording medium. SOLUTION: This target consists substantially of a sintered compact of the B2 rule lattice intermetallic compd. and the relative density thereof is preferably >=99% and the average crystal gain size <=200 μm, more preferably <=30 μm. The deflective strength thereof may be made to >=250 MPa. The oxygen quantity in the target is preferably <=6000 ppm. The magnetic recording medium is formed by a thin film consisting of the B2 rule lattice deposited by the target as at least one layer of the ground film to be formed between a Co-based magnetic film and a nonmagnetic substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a B2-order lattice intermetallic compound target and a magnetic recording medium mainly used for forming an underlayer of a magnetic recording medium such as for a magnetic disk drive.

[0002]

2. Description of the Related Art Conventionally, Co-based magnetic layers have been developed to enable high-density magnetic recording. Generally, an underlayer is formed below the magnetic layer to epitaxially grow the magnetic layer. With respect to this underlayer, lattice constant, crystal orientation, crystal grain size, and film uniformity have been improved in order to grow the magnetic layer soundly and epitaxially. For example, as a conventional underlayer, pure Cr and a Cr alloy are mainly used from the viewpoint of the lattice constant matching with the Co-based magnetic layer.

Recently, a base film of a B2 ordered lattice intermetallic compound has been proposed in EP0704839A1. The above-mentioned document proposes to use a B2 ordered intermetallic compound as an underlayer for directly forming a magnetic film instead of a Cr underlayer, and to use it as a further underlying layer of a pure Cr underlayer. Have been. In particular, it has been reported that when used as a further underlying film of pure Cr, the crystal grains of the Cr film can be made finer and a magnetic recording medium with a high coercive force can be obtained.

[0004]

SUMMARY OF THE INVENTION The inventor of the present invention described the above B2
Examination of the underlayer of the ordered lattice intermetallic compound confirmed that the lattice constant is close to that of the Co-based magnetic layer, and that the crystal orientation and the fine uniformity of the film are suitable for the underlayer of the Co-based magnetic recording medium. . As a method for producing the underlayer of the B2 ordered lattice intermetallic compound, an RF sputtering method or the like can be used as described in the above-mentioned literature and the like. In the sputtering method, a target serving as a supply source of a film composition is required.

The present inventors have studied the preparation of a compound target for forming a uniform film of a B2-ordered lattice intermetallic compound. When a target made of a B2-ordered lattice intermetallic compound was prepared by a melting method, there was a problem that the transverse rupture strength was low and the material was broken during processing. It was confirmed that the casting target of the B2 ordered intermetallic compound formed a somewhat fine chill crystal, a coarse and columnar crystal depending on the cooling direction, and a somewhat fine equiaxed crystal, and the particle size was largely varied. The variation of the crystal grains not only causes the generation of particles, but also causes the thickness of the thin film when formed to vary. In such a case, it is difficult to epitaxially grow a thin film formed on the upper surface of the underlayer, and as a result, the magnetic recording characteristics may be deteriorated. SUMMARY OF THE INVENTION An object of the present invention is to provide a B2-ordered lattice intermetallic compound target having a high bending strength and a magnetic recording medium.

[0006]

The present inventors have found that the transverse rupture force of a B2-ordered lattice intermetallic compound target largely depends on the microstructure of the target. Then, they found that it is necessary to use a sintered target as a means for preventing the large variation in crystal grains confirmed in the casting target. Further, as the intermetallic compound target, the sintered body target was previously adjusted to B2 ordered lattice intermetallic compound powder, and it was found that a target obtained by sintering it could secure a high transverse rupture strength, and reached the present invention. .

That is, the present invention is a target substantially composed of a sintered body of a B2-ordered lattice intermetallic compound. As a method for obtaining a B2-ordered lattice intermetallic compound sintered body, it is possible to produce a compound sintered body by reacting elemental powders at the time of sintering, but in this case, there is a possibility that the structure is coarsened by the reaction heat. There is. Therefore, it is preferable that the target is a B2-ordered lattice intermetallic compound substantially using a B2-ordered lattice intermetallic compound powder as a sintered body.

The target of the present invention has a relative density of 99%.
As described above, it is desirable that the average crystal grain size be 200 μm or less, more preferably 30 μm or less. By satisfying the above-described conditions, a target with a transverse rupture force of 250 MPa or more can be obtained. Further, the amount of oxygen in the target is preferably 6000 ppm or less.

The above-mentioned target of the present invention may be a method of pulverizing an ingot produced by a melting method to obtain a sintering raw material, or a method of forming a sintering raw material by an atomizing method. It is necessary to avoid a reaction with the furnace material due to skull melting or the like, which is expensive. However, this is an effective means when a low oxygen target is required. Therefore, it is desirable to pulverize an intermetallic compound by a reaction sintering method that does not require a melting step to obtain a powder raw material. This method is used in reaction sintering.
There is also an advantage that self-heating during compounding can be used. The target of the present invention can be obtained by sintering the powder obtained by the method described above.

[0010] B formed by the above-described target of the present invention
By making the bi-order lattice thin film at least one of the base films formed between the Co-based magnetic film and the non-magnetic substrate, it is possible to produce a stable magnetic recording medium with less generation of particles and less variation in film thickness. It can be carried out. The definition of at least one layer is that Co is directly deposited on the B2 superlattice thin film.
A magnetic film may be formed, but a thin film such as a Cr or Cr alloy layer, which can be expected to increase the coercive force squareness as a magnetic recording medium, can be arranged on a B2 ordered lattice thin film. Is what it means.

[0011]

An important feature of the present invention is that a B2-ordered lattice intermetallic compound target is obtained by a sintering method. By applying the sintering method, it is possible to suppress a decrease in transverse rupture force due to coarsening of crystal grains, which is a problem when obtaining an intermetallic compound target by a melting method.

In the present invention, by setting the relative density to be 99% or more, it is possible to prevent a reduction in the transverse rupture strength depending on the density. Making the average crystal grain size as small as 200 μm or less is advantageous in that a difference in sputtering speed due to a difference in orientation of crystal grains can be reduced and a uniform film can be obtained. More preferably, it is 30 μm or less. Further, the fine crystal grains have many crystal grain boundaries for absorbing fine strain, which is also advantageous in that the bending strength is improved, and a high bending strength of 250 MPa or more can be obtained. The amount of oxygen in the target is 6000
If it exceeds ppm, the amount of oxides in the target increases, and problems such as abnormal discharge and particles during sputtering may increase rapidly and become a problem. Further, when the amount of oxygen in the target exceeds 6000 ppm, the second
The magnetic properties deteriorate due to an increase in the amount of phases and a decrease in matching.

[0013]

EXAMPLES Samples 1 to 8 shown in Table 1 were mixed with individual elemental metal powders so as to have a desired composition, and then made into a B2-ordered lattice intermetallic compound by a reaction sintering method. Then, it was pulverized with a ball mill to prepare a powder. 1200 pieces of each powder
Sintering under the condition of ℃ 100MPa × 3h, φ101
A target of × 4 t (mm) was produced. Further, samples 9 to
16 is dissolved by a skull dissolution method so as to have a desired composition,
A target of φ101 by precision casting was produced.

Table 1 shows the transverse rupture force, density, and average crystal grain size of each target by volume average diameter by the intercept method. As an example showing a typical structure of the target of the present invention in FIG.
The microstructure of a 00-fold sintered body is shown. As is clear from Table 1 and FIG. 1, according to the present invention, a high-density and fine-crystal grain target having a high bending strength was obtained by sintering the intermetallic compound powder. I understand.

[0015]

[Table 1]

The number of foreign substances having a size of 2 μm or more on the substrate formed with the targets of Samples 1 to 16 was measured. Further, the number of foreign substances having a size of 2 μm or more on the substrate formed by the target of the comparative example was also measured. Table 3 shows the measured number of foreign substances. However, the number of foreign substances in Table 3 is expressed assuming that the number of foreign substances of 2 μm or more on the substrate formed by the target of Sample 1 is 100. As shown in Table 2, the target of the present invention is:
It can be seen that the generation of foreign matter can be suppressed as compared with the conventional target.

[0017]

[Table 2]

[0018]

According to the present invention, a target having a high bending force B2 structure can be provided, so that the target can be easily handled and the generation of foreign matter can be reduced, and a high quality magnetic recording medium can be provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a microstructure micrograph showing a typical structure of a target of the present invention.

Claims (7)

[Claims] 1. A B2-ordered lattice intermetallic compound target substantially consisting of a B2-ordered lattice intermetallic compound sintered body. 2. A B2-ordered lattice intermetallic compound target substantially consisting of a sintered body of B2-ordered lattice intermetallic compound powder. 3. The B2-ordered lattice intermetallic compound target according to claim 1, wherein the relative density is 99% or more and the average crystal grain size is 200 μm or less. 4. The B2-ordered lattice intermetallic compound target according to claim 3, wherein the average crystal grain size is 30 μm or less. 5. The B2-order lattice intermetallic compound target according to claim 1, wherein the transverse rupture strength is 250 MPa or more. 6. The amount of oxygen in the target is 6000 ppm.
The B2 ordered lattice intermetallic compound target according to claim 1 or 2, wherein: 7. A thin film comprising a B2 ordered lattice formed by the target according to claim 1 as at least one layer of a base film formed between a Co-based magnetic film and a non-magnetic substrate. A magnetic recording medium characterized by the above-mentioned.