JPS6226624A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To improve resistance to corrosion and oxidation without using a protective film by forming a thin magnetic metallic film into which the oxide of a rate earth metal is incorporated at 0.1-10wt% on a substrate. CONSTITUTION:A magnetic recording medium 40 is constituted by forming the thin magnetic metallic film 20 into which the oxide of the rate earth metal is incorporated at 0.1-10wt% on the substrate 1 in tight contact therewith. A nonmagnetic material which excels in heat resistance and dimensional stability and has high tensile strength is preferable for the substrate 1; for example, polyester, ceramics, etc. are usable for said substrate. A ferromagnetic metal such as, for example, Co-Ni or Co-Cr alloy can be adopted for the magnetic material to constitute the thin magnetic metallic film 20. The amt. of the magnetic metal in the thin magnetic metallic film 20 is relatively decreased and the coercive force of the film 20 is more deteriorated when the content ratio of the oxide of the rare earth metal exceeds 10wt%. On the other hand, the effect of improving the resistance to corrosion and oxidation is substantially lost at <0.1wt%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium formed by forming a magnetic metal thin film on a substrate, which is an improved magnetic recording medium with improved corrosion resistance and oxidation resistance. It relates to a medium and its manufacturing method.

[Conventional technology]

FIG. 6 is a sectional view partially showing a conventional magnetic recording medium. This magnetic recording medium 30 is formed by forming a ferromagnetic metal thin film 2 of, for example, Co--Cr on a substrate 1 of, for example, polyester. This magnetic metal thin film 2 is formed by, for example, a PVD method, a plating method, or the like. Note that a protective film such as iron nitride may be formed on the magnetic metal thin film 2 in some cases.

[Problem that the invention seeks to solve]

The conventional magnetic recording medium 30 as described above has the following problems.

(2) The magnetic metal in the magnetic metal thin film 2 is susceptible to corrosion depending on environmental conditions, and the magnetic properties of the magnetic metal deteriorate or disappear due to the corrosion. Alternatively, pinhole corrosion may lead to an increase in recording/reproducing errors.

■The magnetic recording medium 30 may instantaneously rise in temperature to about 200 to 300°C due to friction with the recording/reproducing head, and this heat cycle promotes corrosion and oxidation of the magnetic metal in the magnetic metal thin film 2. Ru.

■When the above-mentioned protective film is laminated on the magnetic metal thin film 2, the formation of the magnetic metal thin film 2 and the protective film are separate processes, which makes the management of each process or between processes complicated, and also causes inefficiency in terms of productivity. It is true.

Therefore, an object of the present invention is to provide a magnetic recording medium that can improve corrosion resistance and oxidation resistance without using a protective film as described above, and a method for manufacturing the same.

[Means for solving problems]

In this invention, a rare earth metal oxide is applied on a substrate from 0.1 to
A magnetic recording medium characterized by forming a magnetic metal thin film containing 10% by weight, and a method for manufacturing the same.

[Effect]

By incorporating the above amount of rare earth metal oxide into the magnetic metal thin film, corrosion resistance against moisture in the air at room temperature, corrosion resistance against heat cycles of frictional heat, and oxidation resistance are improved. This is thought to be because the oxide acts as a diffusion barrier for oxygen in the magnetic metal thin film.

〔Example〕

FIG. 1 is a sectional view partially showing a magnetic recording medium according to an embodiment of the present invention. This magnetic recording medium 40 is formed by closely forming a magnetic metal thin film 20 containing 0.1 to 10% by weight of a rare earth metal oxide dispersed on a substrate 1 .

The substrate 1 is preferably a non-magnetic material with excellent heat resistance, dimensional stability, and high tensile strength; for example, polyester, polyolefin, plastics, ceramics, etc. can be used. In addition, its form is film-like,
It can be in the form of a tape, sheet, disk, card, drum, etc.

The magnetic metal constituting the magnetic metal thin film 20 may be, for example, a ferromagnetic metal such as Co-Ni, Co-Fe, or Co-Cr alloy.

Examples of the rare earth metal include Y% HO% Th.

The content ratio of the rare earth metal oxide (for example, Y2O3, etc.) was selected as described above for the following reason. Although it has no influence, it is 10
If the proportion of the oxide exceeds 10% by weight, the amount of magnetic metal in the magnetic metal thin film 20 will be relatively reduced and the coercive force of the magnetic metal thin film 20 will be greatly reduced. preferable. On the other hand, the proportion of the oxide is 0. If it is less than 1% by weight, the effect of improving corrosion resistance and oxidation resistance, which will be described later, is almost lost, so it is preferable to use more than 1% by weight.

In the magnetic recording medium 40 as described above, the magnetic metal thin film 20 has improved corrosion resistance against moisture in the air at room temperature, corrosion resistance against heat cycles due to frictional heat at about 200 to 300°C, and oxidation resistance. do.

This is thought to be because the oxide acts as an oxygen diffusion barrier in the magnetic metal thin film 20. Therefore, there is no need to laminate a protective film such as iron nitride on the magnetic metal thin film 20 as in the conventional case.

Next, some methods of manufacturing the magnetic recording medium 40 having the magnetic metal thin film 20 as described above will be explained with reference to FIGS. 2 to 5.

FIG. 2 shows a method by vacuum evaporation. That is, vacuum chamber 3
The base 1 and, for example, two electron beam heating type evaporation sources 4.6 are disposed within the evaporation source 4. For example, the magnetic metal 5 as described above is used as the evaporation material of the evaporation source 4. The rare earth metal oxide 7 as described above is used.

After the vacuum chamber 3 is evacuated to, for example, 10-' Torr or less, the magnetic metal 5 and the rare earth metal oxide 7 are simultaneously evaporated from the evaporation process '6Q4.6 and deposited on the substrate 1. In this case, the evaporation sources 4 and 6 are adjusted so that the magnetic metal thin film 20 formed on the substrate 1 is
The proportion of the rare earth metal oxide 7 in the mixture is made to fall within the above-mentioned range. However, considering only one evaporation source,
Magnetic metal 5 and rare earth metal oxide 7 are used as the evaporation material.
It is also possible to use a material whose composition has been adjusted in advance to a predetermined composition, that is, a material whose proportion of rare earth metal oxide in the formed magnetic metal thin film 20 is within the above-mentioned range.

According to the method described above, the magnetic metal thin film 20 with good adhesion and uniform film quality can be formed on the substrate 1.

FIG. 3 shows a method using sputtering.

That is, in the vacuum chamber 3, the base 1 and the magnetic metal 5
A composite target 8 in which a rare earth metal oxide 7 is embedded or bonded is made to face the target. After evacuating the vacuum chamber 3 to, for example, about 10-7 Tbrr, a DC voltage or high frequency is applied from a power source 9 between the substrate 1 and the target 8, and an inert gas such as argon is introduced into the vacuum chamber 3. to a vacuum of about 10-4 to 10-2 Torr. As a result, a glow discharge occurs between the base 1 and the target 8, and the target 8 is spattered toward the base 1. In this case, the ratio of the magnetic metal 5 to the rare earth metal oxide 7 in the target 8 is such that the ratio of the rare earth metal oxide 7 in the magnetic metal thin film 20 formed on the base 1 falls within the range described above. Select something like this in advance. According to the method described above, it is possible to form the magnetic metal thin film 20 on the substrate 1 with even higher adhesion strength and uniform film quality.

FIG. 4 shows a method that uses vacuum evaporation and ion beam irradiation in combination. That is, the base 1 and, for example, an electron beam heating type evaporation source 10 are arranged in a vacuum chamber 3, and the evaporation source 10 is
As the evaporation material 11, a magnetic metal and a rare earth metal are prepared in advance to have a predetermined composition, that is, a magnetic metal thin film 2 is formed.
The ratio of the rare earth metal oxide in 0 is adjusted to be within the above-mentioned range. and vacuum chamber 3
After evacuating to, for example, 10-' Torr or less, oxygen ions (oxygen ion beam) are emitted from the ion source 12 to the substrate 1.
While irradiating the evaporator 13, the evaporator a, 10 to the evaporator 11
is evaporated, and the rare earth metal in the evaporator 11 and oxygen ions 13 are reacted on the substrate 1 to form the magnetic metal thin film 20. Alternatively, after first evaporating the evaporation material 11 from the evaporation source 10 to form a thin film on the substrate 1, the substrate 1 is irradiated with oxygen ions 13 from the ion source 12 to oxidize the rare earth metal in the thin film. You can also form things. In either case, rare earth metals are much more easily oxidized, so oxidation of magnetic metals is not a problem. According to the method described above, due to the effect of ion implantation, a magnetic metal thin film 20 with higher adhesion strength and good uniformity of film quality can be formed.
can be formed on the substrate 1. Furthermore, there is no need to prepare a rare earth metal that has been oxidized in advance.

FIG. 5 shows a method using reactive sputtering. The difference from the method shown in FIG. 3 is that the magnetic metal and rare earth metal are used as the target 14 and are adjusted in advance to have a predetermined composition. Sputtering is performed using an alloy cougette or a composite target adjusted to fall within a certain range, and the oxygen partial pressure in the vacuum chamber 3 is set to about 10-5 Torr or less to oxidize only the rare earth metal to form a magnetic metal thin film. 20 is formed on the substrate 1. this is,
This is because, as mentioned above, rare earth metals are much more easily oxidized, and magnetic metals are hardly oxidized under the above-mentioned low oxygen partial pressure. According to the method described above, the magnetic metal thin film 20 with high adhesion strength and good uniformity of film quality can be formed on the substrate 1 with an hour wheel-like device configuration, and a rare earth metal film 20 that has been oxidized in advance can be formed on the substrate 1. There is no need to use .

〔Effect of the invention〕

As described above, according to the present invention, a magnetic recording medium with excellent corrosion resistance and oxidation resistance can be obtained. Therefore, there is no need to form a protective film on the magnetic metal thin film as in the past. Further, according to the manufacturing method of the present invention, a magnetic recording medium having a magnetic metal thin film with high adhesion strength and good uniformity of film quality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view partially showing a magnetic recording medium according to an embodiment of the present invention. 2 to 5 are schematic diagrams for explaining an example of a method for manufacturing the magnetic recording medium shown in FIG. 1, respectively. FIG. 6 is a sectional view partially showing a conventional magnetic recording medium. DESCRIPTION OF SYMBOLS 1... Substrate, 3... Vacuum chamber, 4, 6.10... Evaporation source, 8.14... Target, 12... Ion source, 20... Magnetic metal thin film according to the present invention , 40...
Magnetic recording medium according to this invention FIG. 2 FIG. 3 FIG. 41 5 6

Claims (5)

[Claims] (1) A magnetic recording medium characterized in that a magnetic metal thin film containing 0.1 to 10% by weight of a rare earth metal oxide is formed on a substrate. (2) When manufacturing a magnetic recording medium in which a magnetic metal thin film containing 0.1 to 10% by weight of a rare earth metal oxide is formed on a substrate, the magnetic metal and the rare earth metal are oxidized in a vacuum. 1. A method for manufacturing a magnetic recording medium, characterized by simultaneously depositing a substance on a substrate. (3) In manufacturing a magnetic recording medium in which a magnetic metal thin film containing 0.1 to 10% by weight of a rare earth metal oxide is formed on a substrate, the magnetic metal is A method for producing a magnetic recording medium, comprising sputtering a target containing a rare earth metal oxide and a rare earth metal oxide toward a substrate. (4) When manufacturing a magnetic recording medium in which a magnetic metal thin film containing 0.1 to 10% by weight of a rare earth metal oxide is formed on a substrate, the magnetic metal and the rare earth metal are mixed in a vacuum. A method for producing a magnetic recording medium, comprising the steps of vapor deposition on a substrate and irradiation of oxygen ions onto the substrate. (5) When manufacturing a magnetic recording medium in which a magnetic metal thin film containing 0.1 to 10% by weight of a rare earth metal oxide is formed on a substrate, the magnetic metal and rare earth metal are 1. A method for manufacturing a magnetic recording medium, comprising sputtering a target containing a metal toward a substrate.