JPS61283029A - Magnetic alloy material for producing magnetic recording medium and production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To make the composition of a magnetic thin film uniform by forming the magnetic thin film by a vapor-phase coating method with a magnetic alloy material contg. cobalt and chromium and having <=3mm particle diameter as the vaporization source. CONSTITUTION:A magnetic alloy material contg. cobalt and chromium and having <=3mm particle diameter is used as the vaporization source and the material is coated by vapor-phase coating method on a substrate to form a magnetic thin film. The content of chromium is regulated to 18-23wt.%. The control of the composition when the film is formed becomes difficult at >3mm particle diameter. Consequently, the composition of the magnetic thin film is made uniform and stabilized electromagnetic transducing characteristics can be obtained.

Description

Detailed Description of the Invention (1) Background of the Invention Technical Field The present invention relates to a magnetic alloy material for manufacturing a magnetic recording medium and a method for manufacturing a magnetic recording medium using this alloy material.

Prior art and its problems As magnetic recording media for video, audio, etc., media having a metal thin film type magnetic thin film are being actively developed because of their compactness when wound into tapes.

Among these magnetic recording media, perpendicular magnetic recording media, which are capable of higher density recording, are attracting particular attention.

This perpendicular magnetic recording medium has a Co--Cr magnetic thin film having a perpendicular easy axis of magnetization on the film surface. Various methods have been proposed for manufacturing this magnetic thin film, such as sputtering, vacuum evaporation, ion blating, and plating.

Each of these manufacturing methods has advantages and disadvantages, but in terms of productivity and the like, the vacuum evaporation method and the ion blating method are superior because of their high film formation rate. However, on the other hand, there is a drawback that a magnetic thin film having a uniform composition cannot be stably obtained for a long period of time during the production of the medium.

For example, if an ingot-shaped or pellet-shaped Go-Cr alloy material is used as an evaporation source, the amount of Cr in the evaporation source decreases over time, and the amount of Cr in the magnetic thin film changes significantly.

On the other hand, so-called binary evaporation, in which Co and Cr are each provided on the open side as evaporation sources, has been proposed, but even in this case, special composition control is required and the film composition becomes extremely unstable. .

II. OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic alloy material for an evaporation source that allows a magnetic thin film with a uniform composition to be easily obtained by a vacuum evaporation method or an ion blating method, and a method for manufacturing a magnetic recording medium using the same. It's about doing.

■Disclosure of invention These objects are achieved by the invention described below.

That is, the first invention contains cobalt and chromium.
This is a magnetic alloy material for manufacturing magnetic recording media, characterized in that the particle size is 3 mm or less.

A second invention is a method for manufacturing a magnetic recording medium in which a magnetic thin film containing cobalt and chromium is formed on a non-magnetic substrate, wherein the magnetic recording medium contains cobalt and chromium and has a particle size of 3 mm.
This method of manufacturing a magnetic recording medium is characterized in that a magnetic thin film is deposited by a vapor phase deposition method in which the following magnetic alloy material is used as an evaporation source and is heated and vaporized with an electron beam.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The present invention relates to an evaporation source material for manufacturing a so-called perpendicular magnetic recording medium having a magnetic thin film containing cobalt and chromium, and a manufacturing method using the same.

That is, when depositing a magnetic thin film containing cobalt and chromium on a non-magnetic substrate, a magnetic alloy material (hereinafter referred to as alloy material) for manufacturing recording media containing cobalt and chromium is used as an evaporation source, The magnetic thin film is deposited by a vapor phase deposition method in which this is heated with an electron beam and vaporized.

The alloy material used as the evaporation source contains cobalt and chromium, the composition ratio of which is approximately equal to the composition ratio of the intended magnetic thin film, and usually has a composition of about 18 to 23 fi % of chromium.

Magnetic materials are usually particles such as granules and powders. Alternatively, it may be a sintered body of an aggregate of these particles.
The particle size is 3 mm or less.

If the particle size exceeds 3 mm, it becomes difficult to control the composition during film formation.

The alloy material used in the present invention has such a particle size, and may be a so-called crystal grain or a granule produced by sieving a uniform mass of a mixture regardless of crystallinity.

Alternatively, it may be a powder obtained by pulverizing a certain size into a small powder.

In this case, the shapes of these particles may be various, such as spherical, crushed pieces, flakes, and short fibers.

Furthermore, such a powder may be partially sintered or solidified by heating it below its melting point or to a level where it is partially melted, thereby making it easier to handle.

However, at this time, it is necessary that particles having the above particle diameter remain.

If such an alloy material is used as an evaporation source, each particle undergoes sublimation evaporation during production using the vapor deposition method or ion blating method, so the composition ratio of the evaporation source remains constant. A magnetic thin film can be stably obtained over a long period of time.

In addition, when used as a sintered body, its porosity is 10 to 5.
It is preferable to use about 0%.

Furthermore, such an alloy material may contain iron, nickel, titanium, carbon, oxygen, etc. as a third component in addition to the above-mentioned cobalt and chromium.

Using such an alloy material as an evaporation source, a magnetic thin film is deposited using a vapor phase deposition method such as a vacuum evaporation method or an ion blating method. In this case, the above alloy material is used as an evaporation source,
the prescribed amount.

Place it in a hearth and heat it with an electron beam.

Note that any known electron gun may be used, and there are no particular restrictions on the conditions such as the beam used for heating.
By using an electron beam as a means for heating the evaporation source, sublimation from the alloy material can be stably performed.

The vacuum evaporation method and the ion blating method are not particularly limited, as long as various known apparatuses may be used, and conditions such as the distance between the hearth and the substrate and the film deposition rate may be appropriately determined.

Here, in the vacuum evaporation method, the evaporation source is placed in a high vacuum of 10-5 Torr or less, and in the present invention, the evaporation source is heated by an electron beam method or the like to melt and evaporate, and the vapor is applied to the surface of the substrate, for example. This is a method in which the particles are deposited as a thin film.The kinetic energy obtained by the evaporated particles during this evaporation is 0.1 eV.
~1 eV.

The ion plating method is an atomistic film forming method in which a vapor deposition material is bombarded with sufficient kinetic energy onto the substrate surface before and during film formation.

Sputtering of the substrate by bombarding ions,
There are effects such as heating and ion implantation, which increase adhesion and
Affects nucleation and film growth of deposited films.

This ion blating method is further divided into two types, a plasma method and an ion beam method, depending on the area in which the work is performed.

In the plasma method, the substrate (negative potential) is cleaned by Ar◆ bombardment by direct current glow discharge.

When the evaporation source is heated to vaporize the evaporation material, it is ionized in the plasma, accelerated by strong electrolysis in the dark part of the glow discharge cathode surrounding the substrate, and impinges on the substrate with high energy to be evaporated.

Many methods can be used, including a direct current application method, a high frequency excitation method, and combinations thereof with various heating methods for the evaporation source, and a plasma electron beam method using a hollow cathode plasma electron gun may also be used.

In the ion beam method, ions of the deposition material generated by an ion source such as a sputter type, electron impact type, or improved version of duo plasma (EFF) are extracted into a high vacuum region, and the acceleration voltage is adjusted to clean and deposit the substrate surface. In the cluster ion beam technology (evaporation and crystal growth), which is performed subsequently, the deposition material is ejected into a high vacuum from the injection nozzle of the crucible, and the supercooling phenomenon caused by adiabatic expansion is used to
Three atoms are loosely bonded to each other to form a cluster of atoms, which is then ionized and used.

Furthermore, a so-called arc discharge method may be used.

The arc discharge ion blating method collides the vapor flow obtained by heating and evaporating an evaporation source with thermionic electrons emitted from a thermionic emission source at a place where the density of the vapor flow near the evaporation source is relatively high. In this method, the vapor flow is ionized using an electric field or a magnetic field, and the ionized vapor flow is focused on the adherend in the perpendicular direction to form a film.

The kinetic energy of ions in ion brating is approximately several tens of eV to 5 KeV.

The thickness of the magnetic thin film deposited by such a vapor phase deposition method is usually about O.OS to 1.5 Bm, more preferably about 0.1 to 1.5 Bm. It's Oim.

Furthermore, as mentioned above, there are no particular restrictions on the film formation conditions, etc. 1 Usually, the film deposition rate is about 100 to 2,000 people/sec, more preferably 200 to 1000 λ/sec.
It is considered as sec. This speed is lOOλ/S e
If it is less than C, the influence of residual gas during film formation cannot be ignored, resulting in poor reproducibility and uniformity. Also, 2000
When it exceeds a person/see, the heat concentrates and causes splash °(
(instantaneous abnormal evaporation) may occur.

Examples of the non-magnetic substrate on which the magnetic thin film is deposited include resins such as polyester (PET), polyamide, polyimide, polyphenylene sulfide, polysulfone, wholly aromatic polyester, polyether Jl/ether ketone, polyether sulfone, and polyether imide; Alternatively, metal such as AM, glass, etc. may be used, and there are no restrictions on the shape of the substrate used.

Note that various known calendars may be layered on the magnetic thin film, between the substrate and the magnetic thin film, or on the back surface of the substrate using various known layering methods.

■Specific effects of the invention According to the present invention, a magnetic alloy material for manufacturing magnetic recording media containing cobalt and chromium with a particle size of 3 mm or less is used as an evaporation source, and is heated with an electron beam to vaporize it. Since the magnetic thin film is deposited by a phase deposition method, a magnetic thin film having a constant composition can be stably obtained over a long period of time.

Therefore, the obtained magnetic recording medium has extremely good and stable electromagnetic conversion characteristics. It also has excellent productivity.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

(Example 1) Cobalt and chromium alloy pellets (chromium 20 wt%) produced by an induction heating method were crushed under pressure to obtain granular particles having a particle diameter of 3 mm or less.

100 pieces of this were placed in a water-cooled copper hearth with an internal volume of 30 cm3.
．． g was collected and used as an evaporation source material.

A film-like polyester (PET) is used as a non-magnetic substrate.
) After installing the base, set the vacuum chamber to 2XIC)6 Torr.
Then, the evaporation source material was heated and evaporated using an electron gun.

The pressure during vapor deposition was 2×10 −5 Torr, and the can was water-cooled (can temperature T<30° C.).

A cobalt-chromium thin film having a thickness of 0.47 Lm was obtained over a distance of 20 m by setting the distance between the base and the evaporation source to 30 cm and keeping the power of the electron beam constant.

The composition of the obtained sample was analyzed every 1 m along its length, and the results shown in FIG. 1 were obtained.

Note that the compositional analysis was measured using the intensity of Co and Cr of fluorescent X-rays.

(Comparative Example 1) A sample was obtained in the same manner as in Example 1 except that the evaporation source material was a 25 mmφ x 25 mmb cobalt pharyngeal alloy pellet (chromium 20 wt%).

The obtained sample was similarly analyzed for its composition, and the results shown in FIG. 2 were obtained.

(Comparative Example 2) Cobalt and chromium used as evaporation source materials were placed in separate hearths. Cobalt was made into a block shape, and chromium was made into granules with a particle size distribution of 3 mm or less.

Using an electron gun with a 3-point jumping mechanism,
The input power of each was controlled.

The rest was the same as in Example 1.

FIG. 3 shows the results of the compositional analysis obtained.

(Example 2) In Example 1, the arc discharge ion blating method was used instead of the vapor deposition method used as the vapor phase deposition method.
A sample was prepared according to Example 1.

The composition of the obtained sample was analyzed for each In in the length direction in the same manner as in Example 1, and Cr/Co+Cr
When the composition fluctuation rate (%) was calculated during the amount fluctuation, it was ±2% as in Example 1.

These results clearly demonstrate the effects of the present invention.

[Brief explanation of the drawing]

1 to 3 are graphs showing the relationship between sample position and Cr composition amount in Examples and Comparative Examples of the present invention. FIG, 1 Sample position N (m) FIG, 2 Sample position (m)

Claims (4)

[Claims] (1) A magnetic alloy material for manufacturing magnetic recording media, which contains cobalt and chromium and has a particle size of 3 mm or less. (2) The magnetic alloy material for manufacturing magnetic recording media according to claim 1, which has a chromium content of 18 to 23% by weight. (3) In a method for manufacturing a magnetic recording medium in which a magnetic thin film containing cobalt and chromium is deposited on a non-magnetic substrate, a magnetic alloy material containing cobalt and chromium and having a particle size of 3 mm or less is used as an evaporation source. A method for manufacturing a magnetic recording medium, characterized in that a magnetic thin film is deposited by a vapor phase deposition method in which the magnetic thin film is heated and vaporized with an electron beam. (4) The method for manufacturing a magnetic recording medium according to claim 3, wherein the vapor phase deposition method is a vacuum evaporation method or an ion blating method.