JPS6037524B2 - Method for manufacturing magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a magnetic recording medium by a clusterion beam method.

Conventionally, magnetic recording media have been made by dispersing acicular magnetic powder such as iron oxide or chromium oxide or ultrafine powder of ferromagnetic metal in a resin binder and coating it on a non-magnetic base material. It has been widely used. However, in recent years,
There is a strong demand for high-density recording of information in magnetic recording media, and various improvements have been made. However, in the conventional coated magnetic recording media, the size of the particles of the ferromagnetic powder used is However, it has a limit as the smallest unit of a recording element, and it is theoretically impossible to increase the recording density beyond this, so it has been difficult to meet the demand for higher density recording.

For this reason, recently, with the aim of dramatically increasing recording density, thin film (vapor deposition) type magnetic recording media that do not use a resin binder and whose magnetic layer is made of 100% ferromagnetic material have been developed using the Green method, vacuum deposition method, etc. Active research and development has been conducted using thin film forming methods such as the method, sputtering method, and ion plating method.
Some of them are in practical use.

However, the magnetic recording media obtained by each of the above-mentioned thin film forming methods have their own drawbacks and have various practical problems.

In other words, thin-film magnetic recording media formed by wet plating or vacuum deposition have extremely low density strength between the magnetic layer and the base material, so during recording and reproduction, mechanical friction due to contact scanning with the magnetic head causes However, there was a drawback that the magnetic layer was easily peeled off, abraded, and damaged.

In addition, thin film magnetic recording media formed by sputtering or ion plating improve the adhesion strength between the magnetic layer and the base material, but they do not support DC glow in a low vacuum of 10-3 Torr or higher. Since this is a method of forming a thin film using radiofrequency plasma or high-frequency plasma, the crystallinity of the ferromagnetic thin film layer is adversely affected by the incorporation of residual gas and the incorporation of impurities. There was a drawback in magnetic properties.

In addition, it has drawbacks such as variations and non-uniformity in film quality and magnetic properties due to non-uniform discharge conditions, and these problems still need to be resolved as magnetic recording media for high-performance, high-density recording. I left a lot of. In order to fundamentally solve the drawbacks of thin-film magnetic recording media obtained by the conventional thin-film forming method described above, the present inventors have previously developed a magnetic recording medium having a magnetic layer formed by the clusterion beam method. He proposed a medium (Tokusaku Shoichi No. 54-20957).

Although this magnetic recording medium could be put to practical use as a high-density magnetic recording medium, the inventors of the present invention conducted extensive research to obtain a magnetic recording medium with even better magnetic performance. A magnetic thin film layer formed by bombarding a substrate with a clusterion beam having an incident angle of 30 degrees or more with respect to the substrate exhibits a linear anisotropy of the easy axis of magnetization, and has a coercive force in the direction of the magnetization. The present invention was based on the discovery that the amount increases dramatically. Generally, having an easy magnetization direction in a specific in-plane direction of the magnetic layer gives a favorable result that the magnetization characteristics in that direction are improved.

That is, since the coercive force is increased and the squareness ratio of the magnetization curve is improved, it provides the most favorable characteristics to a magnetic recording medium such as a magnetic tape that utilizes the magnetization characteristics in the in-plane longitudinal direction of the magnetic layer. Therefore, an object of the present invention is to provide a magnetic recording medium that has magnetic properties suitable for high-density recording and that can withstand repeated use and is improved so that the magnetic layer will not be peeled off, abraded, or damaged even when running in contact with a magnetic head. An object of the present invention is to provide a method for producing a medium. The gist of the present invention is to form a ferromagnetic thin film on a substrate made of a non-magnetic material by a class uniform ion beam evaporation method.
A method for manufacturing a magnetic recording medium, characterized in that a clusterion beam having an incident angle of 30° or more with respect to the normal to the base material is made to impinge on the surface of the base material.

Next, the present invention will be explained in more detail. The material made of non-magnetic material used in the present invention includes polyvinyl chloride, polyvinyl fluoride, cellulose acetate, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polycarbonate, polyamide, and polyvinyl fluoride. Polymer materials such as ether sulfon and polyparabanic acid, non-magnetic materials such as aluminum, copper, and copper-zinc alloys, and ceramic materials such as anti-striped materials, porcelain, earthenware, and glass are used.

In the present invention, the shape of the base material made of the nonmagnetic material may be appropriately determined depending on the method of using the magnetic recording medium, and is used in the shape of, for example, a tape, film, disk, or drum.

In the present invention, a thin film of ferromagnetic material is formed as a magnetic layer on the above-mentioned base material by a class uniform ion beam evaporation method.

The class uniform ion beam evaporation method according to the present invention is 10
In a vacuum chamber evacuated to a high vacuum of -4 Torr to 10-3 Torr, a closed Rubbo with an ejection hole supplied with a material that can form a ferromagnetic thin film is heated, and the vapor pressure inside the Rubbo is increased. by ejecting the steam from the ejection hole at a temperature of 10-2 Torr or more, forming clusters composed of 50 to 2,000 atoms of the material,
Furthermore, the cluster is ionized by electron bombardment to form cluster ions, and the cluster ions are concentrated and accelerated by an electric field effect to form a cluster ion beam with high energy of several eV to several thousand volts. - A thin film is formed by projecting an ion beam onto the surface of the substrate.

The class 1 ion beam evaporation method is a migration method in which cluster ions, which are mainly composed of ferromagnetic metal atoms, are bombarded onto the surface of a substrate and are broken down into individual atomic particles by the energy of the bombardment and move on the surface. tion effect, the so-called self-heating effect of the deposited film surface where part of the energy when it hits the surface is converted into thermal energy and raises the temperature locally, and the chemical activation effect due to the presence of ions. , since a thin film is formed, a magnetic thin film with good crystallinity can be obtained, and due to the above effects, there is no need for a particular operation of heating the substrate. It can be suitably applied to a magnetic recording medium used as a base material. In order to form a ferromagnetic thin film layer in the present invention, the materials supplied into the closed rubbo of the clusterion source include cobalt, an alloy containing cobalt, and a mixture of cobalt and other elements. 1 selected from the group
Preferably, it is composed of one species or two or more kinds of materials.

As mentioned above, alloys containing cobalt include cobalt and
For example, phosphorus, chromium, copper, iron, nickel, manganese,
In addition to alloys with gold, yttrium, titanium, bismuth, lanthanum, etc., nickel-cobalt phosphorus alloys, cobalt-
Examples include ternary alloys such as iron-nickel alloys and cobalt-bismuth-sulin alloys.

Further, as a mixture of cobalt and other elements, the other elements include, for example, phosphorus, chromium, copper, iron, nickel, manganese, gold, titanium, yttrium, bismuth, lanthanum, etc. A species or two or more species are selectively used. In the present invention, when forming a thin film of ferromagnetic material on the base material by the class uniform ion beam evaporation method, the cluster ion beam is set at an incident angle of 300 or more with respect to the normal to the base material. It is made to project onto the surface of the base material.

Then, a thin film of ferromagnetic material is formed on the base material, in which the easy axis of magnetization exhibits single-touch anisotropy and the coercive force in the direction of magnetization increases dramatically. When the clusterion beam hits the base material, if it hits the base material at an incident angle of 300 or more with respect to the normal to Motomura, the mechanism is not clear, but the thin film formation process of nucleation and crystal growth occurs. It is presumed that the migration phenomenon has directional dependence, which causes the orientation of the crystal axes of the resulting magnetic thin film, resulting in uniaxial anisotropy of the easy axis of magnetization, resulting in favorable magnetic properties. It is thought that it gives

The thickness of the ferromagnetic thin film is preferably in the range of 0.02 to 1 thickness.

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

FIG. 1 is a diagram showing an example of an apparatus for carrying out the method of manufacturing a magnetic recording medium according to the present invention.

The vacuum chamber 2 in the vacuum chamber 1 can be evacuated to a high vacuum of up to 1×10 −8 Torr by an exhaust system device 4 connected to an exhaust pipe 3 . Inside the vacuum chamber 2, there is a cluster ion source unit 5 (however, the power supply circuit etc. are not shown), a film-like base material 6, its supply roll 7 and take-up roll 8, and a cluster ion beam directed to the film-like base material 6. A vertically movable roll 9 is installed to control the incident angle. FIG. 2 is a detailed sectional view of the cluster ion source unit 5, which is composed of a cluster generation section 15, a cluster ionization section 19, and a cluster ion accelerating electrode 20.

The cluster generation unit 15 includes a closed-type rubbo 11 having an ejection hole 10 , a resistance heating heater 12 , and a suction mechanism 1 .
The ionization part 19 of the cluster is composed of a filament 16 for emitting thermionic electrons.
, a mesh electrode 17 for accelerating emitted electrons with an electric field, and a guard 18 for controlling the electric field.

Furthermore, FIG. 2 shows a power supply installed outside the vacuum chamber 1 for operating the cluster ion source unit 5 and its circuit.

Next, the operation of manufacturing the magnetic recording medium according to the present invention using the above-mentioned apparatus will be explained.

First, as shown in FIG. 1, a supply roll 7 on which a non-magnetic base material 6 such as a polyethylene terephthalate film is wound is installed, and the base film 6 is placed along a movable roll 9 and wound around a take-up roll 8. Arrange so that it can be taken.

A material capable of forming a ferromagnetic thin film is supplied into the closed rubbo 11 of the cluster ion source unit 5, and the cluster ion source unit 5 is installed as shown in FIG.

Next, the movable roll 9 is adjusted and applied to the base film 6.
The incident angle of the cluster ion beam should be 30 degrees or more. As shown in FIG.
Point out the angle made by 6.

Next, the vacuum chamber 2 is heated from 10-4 Torr to 10-8 Torr (usually 10-5 Torr) from the exhaust pipe 3 by the exhaust system device 4.
It is evacuated to a high vacuum (from 10-6 Torr to 10-6 Torr), and at this time, it is wound and rewound to deaerate the adsorbed matter existing on the surface of the film-like substrate 6 and the air caught in the supply roll 7. It is preferable to do so.

When the degree of vacuum in the vacuum chamber 2 becomes constant, the resistance heating heater 12 is heated by electricity through the electrode 14 by the fly source 21, and the vapor pressure in the closed type Lupo 11 becomes from 10-2 torr to several torr. From the nozzle 10 to 1'1
Steam is ejected into the vacuum chamber 2 in a pressure region of 0.00 or less.

The atomic vapor particles ejected from the ejection hole 10 become supercooled due to adiabatic expansion, and form a so-called cluster, which is a mass of particles loosely bonded by van der Waalska bonds made up of the atoms.

In the ionization section 19, the filament 16 is heated by the power supply 22 to emit thermionic electrons, and the electrons are transferred to an electric field by the mesh electrode 17 to which a positive DC voltage of 100V to 1,000V is applied by the power supply 23. It is accelerated, collides with the generated cluster, and ionizes it. Since the ionized clusterions are in a positively charged state, they are transferred to the accelerating electrode 20 by the power source 24 at 100%
It is accelerated by applying a negative DC voltage of 10KV to 10KV to impart high kinetic energy. The clusterions thus accelerated by the electric field impinge in the form of a beam on the surface of the base material placed at an incident angle of 30 degrees or more, forming a thin film. As mentioned above, the method for manufacturing the magnetic recording medium of the present invention is performed at an angle of 30° with respect to the normal to the base material made of a non-magnetic material.
Since a ferromagnetic thin film is formed by impinging a clusterion beam having an incident angle above the surface of the base material, the formed ferromagnetic thin film has a one-touch anisotropy along the axis of easy magnetization. This results in excellent magnetic properties with a dramatically increased coercive force in the axial direction.

Furthermore, in the present invention, in order to form a thin film by projecting a clusterion beam in a high energy state onto Motomura,
The resulting magnetic layer has high adhesion strength and packing density with the base material, and is formed with high surface smoothness, so it can be used as a magnetic recording medium with particularly excellent wear resistance and head crush resistance. be.

Examples of the present invention are shown below.

Example 1 A cluster ion beam evaporation layer having the configuration shown in FIG. 1 loaded with the cluster ion source unit 5 having the shape shown in FIG. 2 was used, and a cobalt lump ( A polyethylene terephthalate film with a thickness of 15 layers was placed on the supply roll 7, movable roll 9, and take-up roll 8 as shown in FIG. Class ion beam evaporation was performed under the conditions shown in the table.

Note that no roll driving was performed, and only the incident angle of the clusterion beam was adjusted using the movable roll 9, and the incident angle was set at 30 degrees.

The thickness of the vapor-deposited magnetic layer made of cobalt on the obtained magnetic recording medium was measured using a reflective interference type film thickness measuring device and was approximately 1.2 mm.
00 angstroms.

In order to examine the adhesion strength between the vapor-deposited magnetic layer and the polyethylene terephthalate base material, a peeling test using cellophane tape was conducted, and no peeling of the vapor-deposited magnetic layer occurred. In addition, in order to examine the magnetic properties, the residual magnetic flux density, coercive force, and squareness ratio of the magnetic layer were measured using a DC magnetization measuring device.

As shown in Table 1, the results showed excellent magnetic properties. Example 2 In the same manner as in Example 1, a magnetic layer made of cobalt was deposited on a polyethylene terephthalate film by ion beam evaporation under the conditions shown in Table 1, with the cluster ion beam incident angle set at 45°.

The thickness of the deposited magnetic layer was measured in the same manner as in Example 1 and was found to be approximately 1,000 angstroms.

Further, a peel test was conducted to check the adhesion strength using cellophane tape in the same manner as in Example 1, and no peeling occurred at all.

Further, the magnetic properties were measured in the same manner as in Example 1, and the results are shown in Table 1. Example 3 In the same manner as in Example 1, under the conditions shown in Table 1, the cluster ion beam incident angle was set to 600, and a magnetic layer made of cobalt was deposited on a polyethylene terephthalate film by cluster ion beam evaporation.

The thickness of the deposited magnetic layer was measured in the same manner as in Example 1 and was found to be approximately 900 angstroms.

In addition, a peeling test using cellophane tape was conducted to check the adhesion strength in the same manner as in Example 1, and no peeling occurred.

Further, the magnetic properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Example 4 A cobalt-chromium alloy ingot (chromium 7 wt%) was supplied to the closed Rubbo 11 using the class ion beam evaporation apparatus used in Example 1, and a polyethylene terephthalate film with a thickness of 15 mm was used as the base material. The material was arranged on a supply roll 7, a movable roll 9, and a take-up roll 8 as shown in FIG. 1, and clusterion beam deposition was performed under the conditions shown in Table 1.

The angle of incidence of the clusterion beam on Motomura is 6.
0o, and the film running speed by roll drive was working board/min. The thickness of the vapor-deposited magnetic layer consisting of a cobalt-chromium alloy composition of the obtained magnetic recording medium was measured in the same manner as in Example 1, and was found to be about 900 angstroms, and no peeling occurred in a peeling test using cellophane tape. Ta. Further, the magnetic properties were measured in the same manner as in Example 1, and the results were good as shown in Table 1.

Comparative Example A magnetic layer made of cobalt was deposited on a polyethylene terephthalate film by ion beam evaporation under the conditions shown in Table 1 on a polyethylene terephthalate film under the conditions shown in Table 1, with the cluster ion beam incident angle set at oo.

The thickness of the Aoi magnetic layer was measured in the same manner as in Example 1 and was found to be approximately 1,500 angstroms.

Further, the magnetic properties were measured in the same manner as in Example 1, and the results are shown in Table 1.

Table 1 From the results shown in Table 1, it can be seen that the magnetic recording medium produced by the method of the present invention has a dramatically increased coercive force and excellent magnetic properties.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the apparatus used in the method of the present invention;
FIG. 2 is an explanatory cross-sectional view showing an example of the cluster ion source unit in the apparatus shown in FIG. 1, and FIG. 3 is an explanatory view showing the relationship between the base material and the cluster ion beam in the method of the present invention. It is. 5...clusterion source unit, 6...
... Base film, 25 ... Central axis of clusterion beam, 26 ... Normal line of base material. Na' prisoner na Z evil o 34

Claims (1)

[Scope of Claims] 1. When a thin film of ferromagnetic material is formed on a base material made of a non-magnetic material by cluster ion beam evaporation, the incident angle is 30° or more with respect to the normal to the base material. A method for producing a magnetic recording medium, comprising the step of projecting a cluster ion beam onto the surface of the base material. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the base material is a polyethylene terephthalate film. 3. The method for manufacturing a magnetic recording medium according to claim 1 or 2, wherein the cluster ion beam contains cobalt.