JPS63183610A - Perpendicular magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain the titled medium having excellent wear resistance by forming the recording medium having a thin alloy film contg. Co, Cr, W, and C as essential components. CONSTITUTION:W and C are incorporated into a magnetic Co-Cr film. The compsn. of the magnetic Co-Cr-W-C film consists preferably of 40-73wt.% Co, 23-32wt.% Cr, 4-25wt.% W, and 0.1-3wt.% C. This alloy excels in the wear resistance, corrosion resistance, heat resistance and high-temp. hardness. However, saturation magnetization decreases and the wear resistance dedegrades with a decrease in the content of Co from the desirable range. The saturation magnetization increases but the perpendicular anisotropy and the wear resistance degrade with an increase in said content from the desirable range. The saturation magnetization increases but the perpendicular magnetic anisotropy and the wear resistance degrade with a decrease in the content of Cr from the desirable range. The saturation magnetization decreases and the wear resistance degrades with an increase in Cr content from the desirable range.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a cobalt-chromium perpendicular magnetic recording medium with excellent wear resistance and corrosion resistance, and a method for producing the same.

"Prior Art" In recent years, with the increasing need for high-density magnetic recording, perpendicular recording has been considered as an alternative to the conventional longitudinal recording. The magnetic recording medium for this perpendicular recording method is a Co-based material with Co-based main component and Cr added thereto.
It is known that Cr-based alloys are suitable for perpendicular magnetic recording media by forming this alloy on various glazed substrates by methods such as splattering, vacuum evaporation, plating, and CVD. This is often done.

However, this method of using a metal film as a magnetic film has inferior lubrication properties compared to the method of applying magnetic powder, which has been commonly used for longitudinal recording, and the wear resistance of the metal film is a problem. Become. In particular, Co--Cr binary alloys have poor wear resistance, causing many problems when put into practical use. This problem is particularly important in floppy disks and magnetic tapes where the magnetic head is always in contact with the magnetic film.C.

This is a major obstacle in the practical application of perpendicular magnetic recording media using -cr-based binary alloys. A similar problem exists in a Co-Cr-W magnetic film, which is a type of Co-Cr based a-based film. Therefore, as a method to solve this problem, a wear-resistant protective film is provided on the surface of the magnetic film. A wear-resistant material (8102, etc.) or a lubricating material (BN) is used as a protective film.
etc.), but none has been found that satisfies the practical requirements of being thin, having excellent wear resistance and lubricity, and having excellent adhesion to magnetic films. In particular, in high-density recording using perpendicular magnetic recording, it is necessary to keep the distance between the magnetic head and the magnetic film as close as possible, and the protective film must be extremely thin and extremely wear-resistant. .

"Problems to be Solved by the Invention" The present invention fundamentally solves the problem of wear resistance of perpendicular magnetic recording media using Co-Cr alloys as described above. The object of the present invention is to provide a perpendicular magnetic recording medium with excellent perpendicular magnetic recording characteristics.

A further object of the present invention is to provide a method for manufacturing such a perpendicular magnetic recording medium.

"Means for Solving the Problem At" That is, the present invention is a perpendicular magnetic recording medium with excellent wear resistance characterized by having an alloy thin film containing Co, Cr, W, and ct as essential components.

Further, the present invention provides a perpendicular magnetic recording medium characterized in that when an alloy thin film containing Co j Cr r W and c'6 as essential components is produced by a sputtering method, an alloy consisting of each element is used as a sputtering recording medium. This is a method for manufacturing a recording medium.

The present invention will be explained in detail below.

The Co--Cr magnetic film according to the present invention is characterized by containing W and C. Co according to the present invention
-Cr -W-C The alloy composition of the magnetic film preferably has a Co content of 40 to 73% by weight and a Cr content of 23 to 73% by weight.
32 wt%, W content 4-25%, C content 0.1
~3%. This alloy has been used as a mechanical material under the name stellite alloy, and has excellent wear resistance, corrosion resistance, heat resistance, and high-temperature hardness.

As the Co content decreases beyond the above range, the saturation magnetization tends to decrease and wear resistance tends to decrease.On the other hand, as the Co content increases beyond the above range, the saturation magnetization increases, but as a result, the perpendicular anisotropy decreases. , and the wear resistance tends to decrease.

In addition, as the Cr content decreases beyond the above range, the saturation magnetization increases, but the perpendicular magnetic anisotropy and wear resistance tend to decrease.On the other hand, as the Cr content increases beyond the above range, the saturation magnetization increases. There is a tendency for the wear resistance to decrease.

The W component of the Co-Cr-W-C magnetic film according to the present invention combines with C and CorCr to form a stellite alloy, which completely improves the wear resistance and improves the crystal orientation and perpendicular magnetic anisotropy. It must have the function of improving
As the W content decreases beyond the above range, the wear resistance tends to decrease and the perpendicular magnetic anisotropy also tends to decrease, while as the W content increases beyond the above range, the saturation magnetization tends to decrease.

The C component of the Co-Cr-W-C magnetic film according to the present invention combines with W and Co*Cy to form a stellite alloy and has the function of improving wear resistance. As the range decreases, the wear resistance tends to decrease, and on the other hand, as the range increases beyond the above range, the C component partially precipitates from the alloy phase, which tends to prevent a homogeneous alloy and impair mechanical properties. .

In addition to the above-mentioned essential components, the alloy used in the present invention also contains K Mn
, Sl * Fe # N1 a Range where other components such as Mo do not impair the properties, for example 10 w for essential components
The content may be about t%.

The present invention is characterized by obtaining an excellent perpendicular magnetic recording medium by using such an alloy thin film made of Co-Cr-W-C. According to the present invention, this alloy thin film obtained by sputtering or the like becomes an excellent perpendicular magnetic recording medium. This is considered to be because the thinned alloy undergoes a phase change, and an alloy phase that has magnetism and whose axis of easy magnetization is perpendicular to the film surface is precipitated.

The perpendicular magnetic recording medium having a Co--Cr--W--C magnetic film according to the present invention is produced by depositing pCo on a substrate by a conventional method such as sputtering, ion beam sputtering, vacuum evaporation, or ion FV-ting. It can be obtained by completely forming a thin film of -Cr-W-C quaternary alloy.

The substrate is not particularly limited, but includes, for example, polyimide film, polyethylene terephthalate film, aluminum, glass, and the like.

By the way, in the present invention, such Co-0r-W-
It has been found that an excellent perpendicular magnetic recording medium can be obtained by using an alloy consisting of the above four elements as a sputtering target when manufacturing an alloy thin film consisting of C by a sputtering method. That is, in order to produce the above-mentioned alloy thin film by the sputtering method, in addition to the method using the sandy alloy target of the present invention, a composite target, etc., which is a combination of a plurality of sputtering targets made of each element, can also be used. According to the present invention, by using the alloy as a total target, it is possible to form an alloy thin film with a homogeneous and fine structure in which each element is well mixed, and the perpendicular magnetic field has excellent properties. A recording medium can be obtained.

"Example" Hereinafter, υ will be explained in more detail with reference to Examples.

Example I Co-Cr-W-C (Cr 26% by weight, W 5% by weight,
An alloy consisting of C065 (by weight %Co)) 1
- A thin film was prepared by a sputtering method.

The target size is 6 inches in diameter and 5 meters thick. Figure 1 shows the magnetic properties of the target.

A magnetron-type high-frequency bipolar sputtering device was used as the sputtering device.

No. 9 Ilex substrate gold was used for the substrate.

After this was fixed on the substrate electrode, the vacuum chamber was evacuated to full vacuum, and the substrate was heated at 300° C. for 1 hour to degas it.

After evacuating the inside of the vacuum chamber to 1×10 Pa or less before spooling or spooling, sputtering was performed by completely introducing Ar gas with a purity of 99.9995% to set k 0.5 Pa in the system.

Sputtering was performed by heating the substrate to 150° C. with a sputtering voltage of 1.5 kV.

The X-ray diffraction pattern of the obtained thin film is shown in FIG. C.

Similar to the Cr-based perpendicular magnetization film, a sharp peak appears at 20-44.4°. The rocking curve at 2θ-44, 4° is shown in FIG. The half width was 2.50, indicating that the vertical alignment was extremely excellent.

FIG. 4 shows the magnetization curve of the film measured by a vibrating sample magnetometer. /, The top shows the magnetization curves parallel and perpendicular to the film surface, respectively. It can be seen that a film with excellent perpendicular magnetic anisotropy is produced.

Example 2 Using the alloy target shown in Example 1, the thickness was about 50 μm.
A thin film was prepared on a polyimide film substrate of m. The film was fixed to a metal support frame with a diameter of about 20 crR.

After fixing this on the substrate electrode, the inside of the vacuum chamber was evacuated, and the substrate was heated at t-300°C for 1 hour to perform degassing treatment, and then all sputtering was performed in the same manner as in Example 1.
A thin film was prepared.

However, the substrate was water-cooled, and the sputtering voltage was 3 kV. The X-ray diffraction diagram of the obtained thin film is shown in FIG.

Similar to the CoCr-based perpendicular magnetization film, a sharp peak appears at 20-44.4°.

The rocking curve at 2θ-44, 4° is shown in FIG. The half-width was 3.6°, and it was found that the vertical alignment was extremely excellent. FIG. 7 shows the magnetization curve of the film measured by a vibrating sample magnetometer. /, soil exhibits magnetization curves parallel and perpendicular to the membrane plane, respectively. It can be seen that the vertical anisotropy is extremely large.

The above sample 'f! :Processed into a 5.25 inch floppy disk and put it into a floppy disk tester for VT
The change in output when the R ring head is fully in contact is shown in FIG. 8 together with the results for a magnetized film made of a CoCr thin film produced under the same conditions.

With the CoCr thin film, the output drops extremely after 10,000 passes, and then gradually decreases, but with the Co-Cr-W-C alloy thin film, the drop in output is small and it can be seen that it has extremely excellent durability.

[Corrosion resistance]

The above-mentioned Co-Cr-W-C film also has extremely excellent corrosion resistance. For example, while the Co-Cy film dissolves in dilute hydrochloric acid in a few hours, the Co-Cr-W-C film dissolves in dilute hydrochloric acid. It was extremely stable in the water and did not change even after being immersed for several days.

[Fine structure]

Ultra-thin section samples were prepared from the above Co-Cr-W-C film and Co-Cr film by ion etching method, and the entire metal structure was observed using a transmission electron microscope in Figure 9 and til.
Shown in Figure o. While the Co-0r film (Fig. 1O) has a clear grain structure, the Co-Cr-W-〇 film (
In FIG. 9), a dense texture with fine stripes is observed, and it is clear that the film has a completely different texture from that of the Co--Cr film. A special feature of the Co-Cr-W-C film is that it has a dense structure with no clear grain boundaries, and this is considered to be one of the reasons for its excellent wear resistance and corrosion resistance.

Example 3 Co-Cr-W-C (Cr 28% by weight, w4-layer Jit
%, C11% by weight remaining, 9Co)
A thin film was prepared in the same manner as in Example 1 using No. 1. Pyrex glass was used for the substrate.

The X-ray diffraction pattern of the obtained thin film is shown in FIG.

A sharp (002) diffraction peak of the Co crystal appears at 44.4 degrees 2θ, indicating that the crystal is oriented perpendicular to the film surface. The rocking curve at 2θ-44, 4° is shown in FIG. The half width is 3.2°.

The magnetization curve of the film measured by a vibrating sample magnetometer is shown in the 13th section.
As shown in the figure. It can be seen that a film with extremely excellent vertical anisotropy is produced.

Example 4 Co-Cr-W'C (Cr 29wt%, W8311
A thin film was produced in the same manner as in Example 1 using an alloy target consisting of 1.4% by weight of C and a balance of J)Co. No. 4 Ilex glass was used for the substrate.

The X-ray diffraction diagram and rocking curve are shown in Figures 14 and 1.
It is shown in Figure 5. Extremely excellent vertical alignment. The half width of the rocking curve is 4.3°. The magnetic properties are shown in FIG.

Example 5 Co-Cr-W-C (Cr 30Kf: %, W121
A thin film was produced in the same manner as in Example 1 using an alloy target consisting of 2% by weight, 2.51% Co, and the remainder Co. /4' Ilex glass was used for the substrate.

The X-ray diffraction diagram and rocking song *i are shown in FIGS. 17 and 18. It can be seen that the vertical alignment is excellent. The half width of the rocking curve is 5.8°. The magnetic properties are shown in FIG. 19.

Example 6 Co-Cr-W-C (Cr 23% by weight, W 20% by weight
, CI! A thin film was prepared in the same manner as in Example 2 using an alloy target consisting of 1) Co.

The X-ray diffraction pattern of the obtained thin film is shown in FIG.

A sharp peak appears at 20-44.0'.

The rocking curve at 2θ-44.0° is shown in FIG. The half width is 3.6°, and like Example 1, the vertical alignment is extremely excellent.

The above sample was processed into a floppy disk in the same manner as in Example 1, and its durability against the ring head was investigated. As a result, the decrease in output after 100,000 passes of head contact was less than 1 dB. It showed superior properties compared to other materials. Note that the alloy target of this example is considered to be weakly magnetic because it contains a large amount of W.

Comparative Example 1 Co-Cr-W (Cr 26i!% by weight, W55% by weight
Example 1 using an alloy target consisting of the remainder j) Co)
A thin film was prepared in the same manner.

The X-ray diffraction pattern and rocking curve of the obtained thin film are shown in FIGS. 22 and 23. 22 shows 20 layers 44
A sharp peak appears at 0°, which seems to indicate excellent vertical orientation, but in the rocking curve shown in Figure 23, the peak shows a unique shape, indicating that the rocker has a unique crystalline state. Recognize.

The magnetic properties of the above sample measured using a vibrating sample magnetic needle are shown in FIG. It can be seen that the sample is almost non-magnetic.

If the rocking curve is vertically oriented, it should show a single peak with symmetry centered on the vertical direction (the center of the figure), but in Comparative Example 1, the peak has a peculiar shape, indicating that the vertically oriented I can say that I have not.

Comparative Examples 2 to 5 A ternary alloy film having a composition close to that of a quaternary alloy was prepared in the same manner as in Example 1, and Comparative Example 2 (31% by weight of Cr, 2% by weight of W, balance F) C
o), Comparative Example 3 (Cr 28wt%, W4 weight range, remaining!1l CO, composition close to 14 yuan, slightly less W),
Comparative Example 4 (Cr 30TLth%, W8 weight ratio, remaining Co, composition close to quaternary, slightly more W), Comparative Example 5 (O
R23 weight dispersion %, W20 weight ratio, residual composition close to C014 original with slightly more W. ) were prepared using all the composite targets at each ratio, and X-ray diffraction patterns were obtained. In both cases, peculiar peaks (such as double peaks) appear in the rocking curves, and they are not vertically aligned.

All magnetic properties were close to non-magnetic. In addition, comparative example 2
Comparative Example 3 is shown in Figs. 25 and 26, Comparative Example 3 is shown in Figs. 27 and 28, Comparative Example 4 is shown in Figs. 29 and 30, and Comparative Example 5 is shown in Figs. 31 and 32.

When this composite target is used, poor vertical alignment results (double peaks and peaks in X-ray diffraction) are often observed.
The state of the formed film varies depending on whether the target is an alloy or a composite.

The composite target was constructed by combining Co, C1 and W targets using the method disclosed in Japanese Patent Application No. 104788/1983.

Comparative Example 6 An alloy thin film was created by sputtering using a quaternary composite target having the same composition as the quaternary alloy of the present invention. The X-ray diffraction diagrams are shown in FIGS. 33 and 34.

Although a vertically oriented film is produced, the half value of the rocking curve is 6.9°, and the orientation is worse than when using an alloy target. The magnetic properties are shown in FIG. 35, and it can be seen that the vertical properties are worse than when using an alloy target.

"Effects of the Invention" As is clear from the above, according to the present invention, by incorporating W and Cf into the Co-Cr-based magnetic film, it has excellent perpendicular magnetic anisotropy and unprecedented wear resistance. All perpendicular magnetic recording media can be provided.

Further, according to the present invention, by using a quaternary alloy as a target, each element is well mixed and an alloy fFi M'fc having a homogeneous and fine structure can be formed.

[Brief explanation of the drawing]

FIG. 1 is a graph showing a magnetization curve obtained by measuring the magnetic properties of an alloy target using a vibrating sample using a magnetometer. FIG. 2 is a graph showing an X-ray diffraction diagram of a magnetic thin film of a perpendicular magnetic recording medium according to the present invention, FIG. 3 is a graph showing a rocking curve, and FIG. 4 is a graph showing a vibration FIG. 2 is a graph showing a magnetization curve measured by a sample magnetometer. 5 to 7 and 11 to 21 are graphs showing the X-ray diffraction diagram, rocking curve, and magnetization curve of the magnetic thin film of the perpendicular magnetic recording medium according to the present invention, respectively. FIG. 8 is a graph showing the results of a wear resistance test of the magnetic thin film of the perpendicular magnetic recording medium according to the present invention. FIG. 9 shows the complete metal composition of the quaternary alloy thin film according to the present invention, and FIG. 10 shows the metal composition of the CoCr binary alloy thin film. FIGS. 22 to 24 are X@ diffraction diagrams, rocking curves, and magnetization curves of CoCrW ternary alloy thin films, respectively. Figures 25 to 31, Figure 33 and Figure 34 are diagrams showing the Xi diffraction patterns and rocking curves of IJ and films used for composite targets, respectively, and Figures 32 and 35 are magnetization curves. It is a graph diagram. 1st figure 1 25emukrn3 2nd figure 2e('nW; 3rd e(0) 4th figure-500111rNJ/Cm' 5th figure 2θC0) 7th figure 500emu/cm3 8th figure... Sen tit missing C ° no no 7) collection? , @ 'S/( )[1 time lesson day 13 figure 16 - 1ooemu/cm' logi shuugei gi hard 1 - loya reward C envy - translation calyx figure 24 figure 25 θ(0) @-f Nemaba Kaiiku Futsubaki No. 35 500 emu/cm3 Procedural Amendment November 1988 190 Commissioner of the Patent Office Kunio Ogawa 1 Indication of Case Patent Application No. 1983-31606 2 Invention Name Perpendicular magnetic recording medium and its manufacturing method 3 Relationship with the case of the person making the amendment Patent applicant name (020) Ube Industries Co., Ltd. 4 Agent address 40 Toranomon, 5-13-1 Toranomon, Minato-ku, Tokyo
Mori Building drawing 6 Correction details Figure 1, Figure 3, Figure 4, Figure 7, Figure 12, Figure 13, Figure 15 Figure 1-25amukm3 Figure 3 θ(0) Figure 12 e( ') Fig. 13 - 500 emu/cm' Fig. 16 - 100 emu/cm' Fig. 18 Fig. 19 Fig. 23 θ (@) Fig. 24 Fig. 32 Fig. 34 e (@)

Claims (4)

[Claims] (1) A perpendicular magnetic recording medium with excellent wear resistance, characterized by having an alloy thin film containing Co, Cr, W, and C as essential components. (2) The content of Co is 40 to 73% by weight, the content of Cr is 23 to 32% by weight, the content of W is 4 to 25%, and the content of Co is 40 to 73% by weight.
2. The perpendicular magnetic recording medium according to claim 1, wherein the content is 0.1 to 3%. (3) A method for producing a perpendicular magnetic recording medium, characterized in that an alloy consisting of each element is used as a sputtering target when producing an alloy thin film containing Co, Cr, W, and C as essential components by a sputtering method. . (4) In the alloy, the Co content is 40 to 73% by weight, the Cr content is 23 to 32% by weight, the W content is 4 to 25%, and the C content is 0.1 to 3%. A method for manufacturing a perpendicular magnetic recording medium according to claim 3.