JPH10261223A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for production for manufacturing a diagonally vapor deposited medium having a higher density and higher crystal orientation property. SOLUTION: Only the deposition chamber 8 is separated in a vacuum chamber 1 in order to increase the energy of vapor deposition particles on a substrate film 2. This deposition chamber 8 is evacuated by another discharge system, by which a differential pressure is generated between the deposition chamber 8 and the inside of the chamber 1 and the energy is applied to the vapor deposition particles by the differential pressure. Further, the directivity of the vapor deposition particles is limited by limiting the width of the opening of the deposition chamber 8 to execute deposition with only the vapor deposition particles from the same direction, by which the structure to enhance the crystal orientability is obtd. The manufacture of the vapor deposited thin films having the denser structure and the higher crystallinity than those of the conventional media is made possible and the magnetic characteristics of the films are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium in which a magnetic layer composed of a magnetic thin film is formed on a non-magnetic support.

[0002]

2. Description of the Related Art In the field of magnetic recording, with the increase in the amount of information to be recorded, there is a strong demand for higher density recording year by year. Along with this, as a magnetic recording medium, instead of the so-called coating type medium in which conventional magnetic particles are dispersed in a binder and applied, a ferromagnetic metal is plated or vacuum thin film forming means (vacuum deposition method, sputtering method or ion A so-called thin film type medium formed by a plating method or the like is becoming mainstream. This metal magnetic thin film type magnetic recording medium is excellent in coercive force, squareness ratio, etc., and it is not necessary to mix a binder which is a non-magnetic material in the magnetic layer unlike the coating type medium, so that the packing density of the magnetic material (in other words, , The amount of magnetization per unit volume) can be increased, and the thickness of the magnetic layer can be extremely reduced as compared with the coating type medium. Therefore, the magnetic recording medium of the metal magnetic thin film type has excellent electromagnetic conversion characteristics in a short wavelength region which will be used more often in the future, and further, recording demagnetization is remarkably small. Since the magnetic recording medium of the metal magnetic thin film type has such excellent properties as described above, it is considered that the magnetic recording medium will become the mainstream as a magnetic recording medium for high-density recording in the future.

FIG. 5 is a schematic view of a conventional continuous winding type vapor deposition machine. In the vacuum chamber 1, the polymer film 2, which is a non-magnetic support, is passed from a take-up roll 3 along a cooling can 6 and guide rolls 10 and 11, and is taken up by a take-up roll 4. The Co particles are deposited by simultaneously heating and melting the Co ingot filled in the crucible 5 disposed below the cooling can 6 with an electron gun. In addition, crucible 5
In the vicinity of the cooling can 6 where Co is to be deposited, a vapor deposition is performed while flowing oxygen gas from the oxygen introducing pipe 7 to introduce oxygen into the film. Further, the orientation angle of the easy axis of the magnetic layer from the in-plane direction of the magnetic layer is changed by moving the high-incidence angle side / low-incidence angle side shielding mask 9 installed below the cooling can 6 to change the incident angle of the vapor deposition particles. It controls by making it do.

In the field of video tape recorders, so-called oblique deposition media have been proposed and put to practical use in order to improve the electromagnetic conversion characteristics and achieve higher output at shorter wavelengths.

[0005] This oblique deposition medium is a so-called oblique deposition method in which a magnetic metal is deposited on a moving and running nonmagnetic support (a polymer film such as a polyester film, a polyamide or a polyimide film) by a vacuum deposition method from an oblique direction. This is a metal thin film type medium in which a magnetic layer is formed by a vapor deposition method. In magnetic tapes manufactured by the oblique evaporation method, the magnetic particles are oriented obliquely to the surface of the non-magnetic support, and the recording density is higher than that of the conventional magnetic tape in which the magnetic particles are oriented in the longitudinal direction. Becomes possible. The tilt angle of the axis of easy magnetization in the magnetic layer of a magnetic tape which is currently in practical use and is obliquely oriented with magnetic particles (hereinafter, obliquely oriented magnetic tape) is about 20 degrees.

In the above obliquely oriented magnetic tape, the magnetic material constituting the magnetic layer is generally Co or Ni.
Is usually performed while blowing oxygen gas onto a moving nonmagnetic support. Thereby, the magnetic layer has a structure in which α-Co magnetic particles (or Co-Ni) and non-magnetic Co-O (or Co-Ni-O) are mixed. Here, oxygen is introduced into the magnetic layer film in order to reduce medium noise by making crystal grains fine, and to increase oblique shape anisotropy by making the magnetic layer a columnar structure. It is.

[0007]

In the field of VTRs using such obliquely oriented vapor-deposited tapes, it is desired that the tapes have a larger capacity, smaller size and lighter weight in order to achieve higher density recording. In order to realize high-density recording higher than that of the current tape, it is effective to perform recording using a shorter wavelength than the current recording wavelength. By doing so, more information can be recorded on a tape of the same length.

However, as the recording wavelength becomes shorter,
Since the magnetization recorded on the tape tends to self-demagnetize,
The residual magnetization becomes small, and as a result, the reproduction output becomes small. To prevent this, it is effective to improve the coercive force of the magnetic layer. By increasing the coercive force, it is possible to form a recording magnetization in the magnetic layer that can counter the self-demagnetizing field.

In order to improve the coercive force of the magnetic layer and the reproduction output at a short wavelength, it is effective to increase the crystal orientation of the magnetic particles in the magnetic layer. Therefore, an object of the present invention is to provide a manufacturing method for manufacturing an oblique deposition medium having higher density and higher crystal orientation than before.

[0010]

A vapor deposition apparatus for producing an oblique vapor deposition medium is usually a vacuum chamber 1 as shown in FIG. The magnetic material filled in the crucible 5 in the vacuum chamber 1 is dissolved by an electronic boom or the like into a vapor stream, and a thin film is deposited on the non-magnetic support film 2 running on the cooling can 6.

In general, in a vacuum thin film forming process, it is important to increase the energy of particles to be formed in order to produce a dense and highly crystalline thin film. For example, when comparing the sbutter method and the vapor deposition method, a film having a high crystallinity can be generally manufactured by a sbutter method having a high energy of particles.

In the vapor deposition method, a method is used in which a material to be formed is heated and melted to a temperature equal to or higher than its melting point and deposited on a substrate in a vapor stream. However, the energy of vapor deposited particles is not so high. Therefore, the present inventors separated the film formation chamber only in the vacuum chamber and increased the energy of the vapor deposition particles on the substrate, and evacuated the film formation chamber with a separate exhaust system. It was devised to create a pressure difference between the inside of the chamber and to give energy to the deposited particles by the pressure difference (see FIG. 1). Furthermore, in the method of the present invention, energy can be given to the deposited particles, and at the same time, the deposition rate is increased, so that residual gas molecules and the like are less likely to be mixed into the deposited film,
The effect of forming a film with higher density and higher purity can also be obtained.

As a result, it becomes possible to produce a vapor-deposited thin film having a denser structure and higher crystallinity than the conventional medium, and the magnetic properties of the film are improved. In addition to the squareness ratio indicating the orientation, the saturation magnetization is increased by high density and high packing, and the coercive force is increased by improving the orientation. The reproduction output of the magnetic recording medium thus obtained is improved as compared with the conventional medium.

At the same time, as shown in FIG. 2, by limiting the width of the opening of the entrance where the vapor deposition particles enter the film forming chamber, the directionality of the vapor deposition particles is restricted, and only the vapor deposition particles from the same direction are used. The structure was such that crystal orientation was enhanced by forming a film. Further, by providing a guide for guiding the vapor deposition particles inside or outside the opening at the entrance of the film formation chamber, the vapor deposition direction of the particles can be further improved.

[0015] By these means, the crystal orientation of the deposited thin film is greatly improved, and the magnetic characteristics are thereby improved, so that the reproduction output can be improved as compared with the conventional magnetic recording medium.

[0016]

According to the present invention, in order to increase the deposition particle energy on a substrate, a film forming chamber is separated in a vacuum chamber and exhausted by another exhaust system to generate a differential pressure between the chamber film forming chambers. Energized the deposition stream. Furthermore, by restricting the size of the opening portion of the entrance of the film forming chamber, the flying direction of the vapor deposition particles is restricted, or a guide is provided at the opening of the entrance of the film forming chamber so that the flying direction of the vapor deposition particles is kept in a certain direction. To improve the crystal orientation.

While the shielding mask 9 controls the incident angle of the vapor deposition particles on the high incident angle side and the low incident angle side installed below the cooling can 6, the size of the opening at the entrance of the film forming chamber is reduced. By restricting, the flying direction of the deposited particles is restricted, and the orientation of the deposited film is enhanced. Here, the size of the opening at the entrance of the film forming chamber means, for example, that the lengths a and b of each side of the opening in FIG. 2 are limited, and the length depends on the width of the moving substrate of the magnetic tape. Since the length a is regulated, the length b of the opening in FIG. 2 is actually adjusted.

According to the method of manufacturing a magnetic recording medium of the present invention, a magnetic recording medium having a higher density or a higher crystal orientation can be manufactured as compared with the medium of the prior art, and the magnetic characteristics and, consequently, the reproduction output (particularly, short wavelength output) can be obtained. Can be improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

FIG. 1 is a schematic diagram showing the basic structure of the continuous winding type vapor deposition machine of the present invention. In the vacuum chamber 1, the polymer film 2, which is a nonmagnetic support, is moved from a winding roll 3 to a cooling can 6 and guide rolls 10 and 11.
And is wound up by the take-up roll 4. Co
Is deposited by simultaneously heating and dissolving the Co ingots filled in the crucible 5 arranged below the cooling can with an electron gun. A film forming chamber 8 is provided below the crucible 5 and below the cooling can 6 where Co is deposited. Vapor deposition is performed near the cooling can 6 in the film forming chamber 8 while flowing oxygen gas from the oxygen introducing pipe 7 to introduce oxygen into the film.

Further, the orientation angle of the axis of easy magnetization of the magnetic layer from the in-plane direction of the magnetic layer is adjusted by moving the high-incidence angle side and low-incidence angle side shielding masks 9 installed below the cooling can 6 so that the vapor deposition particles are incident. It is controlled by changing the angle.

The film forming chamber 8 is made of stainless steel, and is independently evacuated by a vacuum pump separate from the vacuum chamber 1.
FIG. 2 is an enlarged view of the side of the vapor deposition section where the opening 8a of the film forming chamber 8 is provided. Thus, by limiting the width of the opening 8a of the film forming chamber 8, the directionality of vapor deposited particles is restricted. Crucible 5
The particles evaporated in the step are drawn into the film forming chamber 8 from the opening 8 a by the pressure difference between the film forming chamber 8 and the vacuum chamber 1, and are formed on the base film 2.

Example 1 An oblique evaporation medium was manufactured using the evaporation apparatus shown in FIG. The fabrication conditions are as follows.

Film forming conditions Ultimate vacuum before vapor deposition: 2 × 10 ⁻³ Pa Ingot: Co ₁₀₀ base film: polyethylene terephthalate (PE
T) Incident angle: 45 ° to 90 ° Oxygen introduction amount: 0.55 1 / min Vacuum degree during evaporation: 2 × 10 ⁻² Pa Total magnetic layer thickness: 180 nm Size of opening 8a of film forming chamber 8: a = 120 mm, b = 6
0 mm Ultimate vacuum inside the film forming chamber 8: 5.0 × 10 ⁻⁵ Pa

As shown in FIG. 4, a protective film 13 made of carbon is formed on the original tape having the magnetic layer 12 formed on the non-magnetic support 11 by 8 (nm). The top coat layer 14 was formed and finally cut into a predetermined tape width to complete a magnetic tape.

Comparative Example 1 For comparison, a magnetic tape was manufactured using a conventional vapor deposition apparatus (FIG. 5). The manufacturing conditions are all the same as in Example 1. The thickness of the magnetic layer was the same as 180 nm. Table 1
9 shows the magnetic characteristics and the reproduction output of the oblique deposition medium manufactured by the manufacturing method of Example 1 and the medium of Comparative Example 1 manufactured by the conventional apparatus. However, for the reproduction output, the recording wavelengths of 0.5 μm and 0.3 μm were used.
m, and the value of Comparative Example 1 was set to 0 [dB].

[0027]

[Table 1] As can be seen from Table 1, the magnetic properties such as saturation magnetization, coercive force, squareness ratio and coercive force squareness ratio of the medium are improved by the manufacturing method of Example 1, and the reproduction output is accordingly reduced. improves. In particular, according to the present embodiment, the output of the short wavelength is further improved by increasing the coercive force of the medium.

[0028]

According to the present invention, it is possible to form a magnetic layer having a higher density and a higher crystallographic orientation as compared with the conventional oblique deposition medium. The characteristics are improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a continuous winding type vapor deposition machine of the present invention.

FIG. 2 is an enlarged view of a film forming chamber portion of the continuous winding type vapor deposition machine of the present invention.

FIG. 3 is an enlarged view of a film forming chamber portion of the continuous winding type vapor deposition machine of the present invention.

FIG. 4 is a cross-sectional view of a magnetic tape manufactured by the manufacturing method of the present invention.

FIG. 5 is a schematic view of a conventional continuous winding type vapor deposition machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Polymer film 3 Take-up roll 4 Take-up roll 5 Crucible 6 Cooling can 7 Oxygen introduction pipe 8 Film formation room 8 Film formation room 9 Shield mask

Claims (3)

[Claims] An evaporation source is deposited on a surface of a nonmagnetic support in a vacuum chamber, and a magnetic layer formed of a magnetic thin film having an easy axis of magnetization inclined obliquely to the surface of the nonmagnetic support forms a magnetic layer. The method for producing a magnetic recording medium according to claim 1, wherein a vapor flow of the particles deposited on the surface of the non-magnetic support is introduced at a high energy. 2. A deposition chamber having an opening through which vapor deposition particles fly is provided in a vapor deposition section on the surface of a nonmagnetic support, and the size of the opening of the film deposition chamber on the steaming source side is limited. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the flying direction of the magnetic recording medium is restricted. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein a pressure difference is provided between the film forming chamber and the vacuum chamber.