JPS6035332A - Magnetic storage body - Google Patents

Abstract

PURPOSE:To obtain a nonmagnetic metallic base layer which has good contactness with an alloy substrate and is smaller than chromium in film thickness where the same coercive force is obtained by covering the alloy substrate with a nonmagnetic alloy layer, and forming the nonmagnetic metallic base layer made of molybdenum or tangsten thereupon. CONSTITUTION:An aluminum alloy disk which is so finished as to have a surface with sufficiently small undulations by lathe work and heat correction as the alloy disk 1 is plated with nonmagnetic alloy 2 and nickel-phosphorus alloy to about 50mum thickness, and this nickel-phosphorus plating film is polished into a specular surface up to 0.02mum maximum surface roughness and 30mum thickness. Then, this nickel-phosphorus plating film is coated with molybdenum as the metallic base layer 3 by a high-frequency sputtering method to 0.5mum. The base layer 3 increases the coercive force of the metallic magnetic medium 4 as shown in a figure. Then, the molybdenum sputtered film is coated with cobalt to 500Angstrom as the metallic magnetic medium 4 by the high-frequency sputtering method. Further, this metallic magnetic medium 4 is coated with SiO2 to 200Angstrom thickness by the high-frequency sputtering method to obtain a magnetic disk.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in magnetic storage devices (magnetic disk devices, magnetic drum devices, etc.).

The magnetic storage bodies currently in practical use have discontinuous media. This discontinuous media magnetic storage body is γ-
Magnetic storage materials are manufactured by mixing and dispersing magnetic particles such as Fe203.0rb2, Fe, , l'e-Co, etc. in a binder made of organic resin, coating the mixture on a substrate, drying it, and firing it. In recent years, due to the demand for higher storage densities in magnetic storage media, research and development of magnetic storage media with a large coercive force of 1 from continuous thin film media has become active. Ite 7aJ Tsuwa, I'm here.

This continuous thin film medium is mainly used in plating, vacuum evaporation, sputtering,
It is made using techniques such as ion blating. W,T
, Maloney: IEBE Trans, Magn.
In MAG-15, 1135 (1979''), a magnetic memory body is known in which a glass plate is coated with chromium, and then a thin cobalt film is coated on top of it, but chromium easily peels off from the substrate and has a high density. The thickness of the chromium film that provides a coercive force suitable for recording is as thick as 0.5 μm.

In view of the above-mentioned current situation, the present invention has good cleanliness with the substrate,
The present invention provides a magnetic memory comprising a nonmagnetic metal underlayer having a film thickness thinner than that of chromium and having the same coercive force.

Tf, ie, the uninvented magnetic memory, has an alloy substrate coated with a non-magnetic alloy layer or a non-magnetic oxide layer, and a non-magnetic layer of molybdenum or tungsten is coated on the non-magnetic alloy layer or non-magnetic oxide layer. A magnetic alloy thin film medium or a magnetic oxide thin film medium is coated with a magnetic metal underlayer interposed therebetween, and a protective film is coated on the medium.

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial cross-sectional view of the magnetic storage body of the present invention.

In FIG. 1, aluminum alloy is most often used as the alloy substrate 1 of the magnetic memory because it is light, easy to work with, and inexpensive, but titanium alloy may also be used in some cases. The surface of the substrate is finished by machining into a surface having small undulations (50 μm or less in the circumferential direction and 100 μm or less in the radial direction). ) Next, a nickel-phosphorus alloy is plated on one side of this substrate 1 as a non-magnetic alloy layer 2, and the surface of this base body 2 is mechanically polished to a maximum surface roughness of 0.03 μn1 or more.
There is a mirror finish on the bottom. Next, a nonmagnetic metal underlayer 3 of molybdenum or tungsten is coated on the mirror-polished nonmagnetic alloy layer 2 by high frequency sputtering.

The nonmagnetic metal underlayer 3 of molybdenum or tungsten increases the coercive force of the metal magnetic medium 4 as shown in FIG.

Its young fruit is larger than chromium, and the coercive force of the magnetic medium 4 changes depending on the thickness of the underlayer 3, but the thickness of the underlayer is required to be 0.1 μm or more in order to manufacture a practical magnetic memory. do. On the other hand, since the coercive force of the magnetic medium 4 is almost saturated when the thickness of the underlayer 3 is 0.8 μm, a thickness of 0.8 μm or less is sufficient.

It is clear that an alloy containing molybdenum or tungsten is also effective for the non-magnetic metal underlayer 3. Next is the above.

A metal thin film medium typified by cobalt is coated on the magnetic metal underlayer 3 as a metal magnetic medium 4 by high frequency sputtering. Next, a protective film 5 typified by 8i02 is coated on the metal thin film medium 4 by high frequency sputtering.

As described above, it has been found that a nonmagnetic metal underlayer of molybdenum or tungsten has the effect of increasing the coercive force of a magnetic thin film medium.

The protective film coated on the metal thin film medium 4 must be hard, and may be made of metals such as osmium, ruthenium, iridium, manganese, tungsten, or silicon, titanium, tantalum, or oxidation of 1fnium. Preferred are nitrides, carbides, boron, carbon, alloys of boron and carbon, or polysilicic acid.Furthermore, on the protective film 5, R-G (R is saturated or unsaturated hydrogen chloride or fluorine having 10 to 40 carbon atoms) is preferable. hydrocarbon, G is 0
OOH, OH, NH2, 0OOR, S+(OR')s
, 0ONH, rl, etc.) may also be applied.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example 1 Alloy disk 1 was finished with sufficiently small waviness (50 μm or less in the circumferential direction and 10 μm or less in the radial direction) on the lower right surface by Q disk machining and thermal straightening. As No. 2, a nickel-phosphorus alloy was plated to a thickness of about 50 μm, and this nickel-phosphorus plating film was mirror-polished to a maximum surface roughness of 0.02 μm and a thickness of 30 μm.

Next (metal base layer 3 on top of the nickel-phosphorus plating film)
0.5 μm of molybdenum by high frequency sputtering method.
coated. Next, on this molybdenum sputtered film, cobalt%5 was deposited as a metal magnetic medium 4 by high frequency sputtering.
00A coated. Furthermore, 5i is placed on top of this metal magnetic medium 4.
A magnetic disk was fabricated by coating 02 to a thickness of 20 OA by high frequency sputtering. Coercive force HC2 Residual magnetic flux density B
r(BsXS) are t'L6000e and 1200G respectively
So, one.

Example 2 A magnetic disk was fabricated in the same manner as in Example 1 except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing 20 atomic percent of nickel in total and 12 atomic percent of molybdenum. Hc and Br are 9000e and 4300G respectively
Met.

Example 3 A magnetic disk was prepared in the same manner as in Example 1 except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing 20 atomic percent of nickel and 15 atomic percent of rhodium in total. Hc and Br were 9500e and 9000G, respectively.

Example 4 A magnetic disk was fabricated in the same manner as in Example 1, except that molybdenum was coated with a thickness of 0.35 μm as the nonmagnetic metal underlayer 3 by high frequency sputtering. He, Br is 5500e, 12
Ivy in 000G.

Example 5 A magnetic disk was fabricated in the same manner as in Example 1, except that tungsten was coated with a thickness of 0.5 μm as the nonmagnetic metal underlayer 3 by high frequency sputtering. Hc, Br is 6000e, 120
It was 00G.

Example 6 A magnetic disk was fabricated in the same manner as in Example 1 except that tungsten was coated with a thickness of 0.35 μm as the nonmagnetic metal underlayer 3 by high frequency sputtering. Hc and Br are 5500e.

It's 12000G.

Example 7 A magnetic disk was made in the same manner as in Example 1, except that a molybdenum alloy containing 20 atomic percent of aluminum was coated as the non-magnetic metal underlayer 3.Example 8 As in Example 1, however, a non-magnetic metal underlayer was coated with a molybdenum alloy containing 20 atomic percent of aluminum. A magnetic disk was made by coating a tungsten alloy containing 20 atomic percent of aluminum as the layer 3.

Example 9 Same as Example 1, except that the surface of the aluminum alloy disk '1 was coated with aluminum oxide by anodizing to form a non-magnetic metal oxide layer as a non-magnetic alloy layer, and the aluminum oxide was coated with a maximum surface roughness of 002 μm. Finished with mirror polish.

Example 10 Magnetic disks were prepared in the same manner as in Example 1, except that the following materials were coated as protective films to a thickness of 200 Å by sputtering.

Example 11 Same as Example 1 except that TetrahyMc+ was used as a protective film.
A 2.0 weight percent alcohol solution of -1-silane was applied by the Sveen coating method, and then baked at 20° C. for 3 hours to produce a magnetic disk.

Example 12 Example 1 (l!) A magnetic disk was made in the same manner as in Example 1, except that the metal magnetic medium 4 was coated with γ-FezOs+ as a magnetic oxide thin film medium = Hc and Br were each 10000e,
2500 Gr:.

Example 13 A magnetic disk was made in the same manner as Example 1 (!) except that it was not coated with Sin.

Comparative Example Example 1 (!) A magnetic disk was made in the same manner, except that 0.5 μm of chromium was coated as the metal underlayer 3.

He and Br are tL4500e and 12000G respectively.

Using the magnetic disks shown in Examples 1 to 13 above! As a result of magnetic conversion characteristics, head wear tests, and environmental tests, the following characteristics were obtained. A wear test with the head was performed with 20,000 contact start-stop tests, and no scratches were found on the disk surface.Also, in an environmental test, when left at a temperature of 80°C and relative humidity of 90% for 6 months, there was no damage from the board. No peeling was observed. In addition, regarding electromagnetic conversion characteristics, high-density recording of 30,000 to 70,000 BPI was achieved.
Only the recording density of I) could be achieved. In an environmental test, the chromium of the metal underlayer 3 peeled off from the substrate when it was left at a temperature of 80°C and a relative humidity of 90% for 6 months. In addition, in a 20,000-time contact start-stop test, which is a wear test with the head, chromium peeled off from the substrate midway through, causing a crash, and it was found that the sticking power of chromium was very poor.

Furthermore, when the disk surface was observed under a microscope, many cracks were seen, and therefore the number of errors was higher than the 1000 in the example.
It was double that.

From the above results, the magnetic memory of the present invention has excellent environmental resistance, wear resistance, and high recording density characteristics, and in particular, the magnetically exclusive metal underlayer of molybdenum or tungsten has excellent adhesion to the substrate. I found out that

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of the magnetic storage body according to the first aspect of the present invention. In the figure, 1 is a substrate, 2 is a nonmagnetic alloy layer, 3 is a nonmagnetic metal underlayer, 4 is a metal thin film medium, and 5 is a protective film. FIG. 2 is a partial sectional view of the magnetic storage body according to the second aspect of the present invention. In the figure, l is a substrate, 2 is a nonmagnetic alloy layer, 3 is a nonmagnetic metal underlayer, and 4 is a metal thin film medium. FIG. 3 is a characteristic diagram showing the change in the coercive force of the magnetic medium with respect to the thickness of the nonmagnetic metal underlayer when the metal thin film medium is made of cobalt and has a film thickness of 50 OA. Figure 1 Figure 2 Figure 3 O○25 0.50 075 1.00 Thickness of metal base layer 3 (μm)

Claims (1)

[Claims] (1) A magnetic alloy layer or a non-magnetic oxide layer is coated on the alloy substrate, and a non-magnetic gold layer of molybdenum or tungsten is further applied on the non-magnetic alloy layer or the non-magnetic oxide layer.
1. A magnetic memory comprising a magnetic alloy thin film medium or a magnetic oxide thin film medium coated with an underlayer interposed therebetween, and a protective film coated on the medium. (2) A non-magnetic alloy layer or a non-magnetic single change substance layer is coated on the alloy & plate, and a non-magnetic metal underlayer of molybdenum or tungsten is further applied on the non-magnetic alloy layer or non-magnetic oxide layer. A magnetic recording body characterized by being coated with an alloy thin film medium or a magnetic oxide thin film medium. (3) The magnetic memory according to claim 1, wherein the nonmagnetic alloy layer is a nickel-phosphorus alloy. (4) The magnetic memory according to claim 2, wherein the nonmagnetic alloy layer is a nickel-phosphorus alloy. (5) The magnetic memory according to claim 1, wherein the nonmagnetic oxide layer is aluminum oxide. (6) The magnetic memory according to claim 2, wherein the nonmagnetic oxide layer is aluminum oxide. (7) The magnetic storage body according to claim 1, wherein the magnetic alloy thin film medium is cobalt or an alloy containing cobalt. (8) The magnetic recording medium according to claim 2, wherein the magnetic alloy thin film medium is cobalt or an alloy containing cobalt.
body. (9) The magnetic storage body according to claim 1, wherein the magnetic oxide thin film medium is γ-Fe,.03. (1() The magnetic memory according to claim 2, wherein the magnetic oxide thin film medium is γ-Fe2O3. (11) Claim 2, wherein the protective film is osmium, ruthenium, iridium, manganese, or tungsten. The magnetic memory body according to claim 1. The magnetic memory body according to claim 1, wherein the protective film is an oxide, nitride, or carbide of silicon, titanium, tantalum, or hafnium. 0■ Protective film The magnetic memory according to claim 1, wherein is boron, carbon, or an alloy of boron and carbon.
Magnetic storage medium described in Section 1.