JPH0797681A - Film forming method and film forming device - Google Patents

Abstract

PURPOSE:To efficiently obtain films having a uniform compsn. by acting vibrations in a material in a vessel at the time of cooling the material in the method for producing a magnetic recording medium, etc., by depositing the evaporated particles of the material to form the films. CONSTITUTION:The magnetic recording medium is produced by operating an electron gun in, for example, the vacuum vessel to evaporate the molten alloy 13 in a crucible 8 and depositing the magnetic metal on a polyethylene terephthalate film. The base of the crucible 8 is provided with plural pieces of triangular projecting parts 12 so as to project to the inner side thereof in this method. The vibrations are acted on the crucible 8 by an ultrasonic vibration generator 14 disposed in the base of the crucible 8 at the time the film forming operation is stopped and the alloy 13 in the crucible 8 cools during the cource thereof. As a result, the alloy 13 solidified on cooling is uniform. Then, the alloy particles of the uniform components evaporate successively from right after the start of the evaporation. The films having the uniform compsn. are thus efficiently obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a magnetic recording medium, for example.

[0002]

BACKGROUND OF THE INVENTION In a magnetic recording medium such as a magnetic tape, due to a demand for high density recording, a binder resin is not used as a magnetic layer provided on a non-magnetic support, instead of a coating type using a binder resin. A metal thin film type that is not used has been proposed. That is, it is well known that a magnetic recording medium having a magnetic layer formed by a dry plating means such as vacuum deposition, sputtering or ion plating has been proposed. Since the magnetic recording medium of this type has a high packing density of magnetic material, it is suitable for high-density recording.

An apparatus for producing a magnetic recording medium by such dry plating means is generally constructed as shown in FIG. In FIG. 3, reference numeral 21 denotes a cooling can, 22a
Is polyethylene terephthalate (PET) film 23
Of the PET film 23, a roll on the winding side of the PET film 23, a crucible 24, a magnetic metal 25, and a vacuum container 26. Then, after evacuating the inside of the vacuum chamber 26 to a predetermined vacuum degree, the electron gun is operated to evaporate the magnetic metal 25 in the crucible 24, and the evaporated particles of the magnetic metal 25 are deposited on the PET film 23 ( A magnetic recording medium is manufactured by vapor deposition.

However, there is a demand for further improvement in manufacturing technology using such a vapor deposition apparatus. For this reason, a technique of applying ultrasonic vibration to the crucible 24 during vapor deposition work has been proposed for the purpose of making the vapor deposition film uniform (Japanese Patent Laid-Open No. 5-182196).

[0005]

DISCLOSURE OF THE INVENTION According to the technique of applying ultrasonic vibration to the crucible during the vapor deposition work, the vapor deposition film can be made uniform, but the purpose is difficult to be achieved immediately after the vapor deposition work is started. It has been found that the magnetic film obtained immediately after that is not homogeneous and has many defective products, which causes a problem of low production yield.

As a result of earnestly studying the cause of this problem, it has been found that the alloy contained in the crucible has a problem. That is, when the vapor deposition operation is stopped for some reason and the crucible is cooled at that time, the alloy in the crucible solidifies from the molten state. By the way, this solidification does not proceed to uniform solidification, but the respective components become unevenly distributed due to differences in specific gravity and freezing point, etc. In the solidified state, the A component and the B component become uniform. It is not mixed. Then, in such a state, if the electron gun is operated to evaporate the alloy in the crucible and deposit it on the PET film, there is no uniform mixture of the A component and the B component immediately after the start of evaporation, For example, the evaporation of only the A component started, and thus the intended film of the alloy component could not be obtained. Even if ultrasonic vibrations are applied along with the start of evaporation, it takes time to obtain a uniform mixed state, and as a result, the film deposited up to that point is not uniform and preferentially The amount of the evaporated A component is reduced to that extent, the ratio of the A component and the B component present in the crucible fluctuates to some extent, and the composition of the obtained film becomes slightly different. Will be left.

In view of the above, as a result of further intensive studies, it is preferable to apply ultrasonic vibration to the crucible during cooling rather than to apply ultrasonic vibration to the crucible at the start of vapor deposition. I got the revelation that it might be. That is, if ultrasonic vibrations are applied during cooling, it is possible to obtain revelation that the alloy solidified by cooling will be uniform, and therefore alloy particles of uniform components will evaporate immediately after the start of evaporation. It was thought.

The present invention has been achieved based on such knowledge, and an object of the present invention is to provide a technique capable of efficiently forming a film having a uniform composition. An object of the present invention is a film forming method for evaporating a material in a container and depositing evaporating particles on a support, wherein vibration is applied to the material in the container when the material in the container is cooled. It is achieved by the following film forming method.

In this film forming method, the vibration is 20 k.
It is preferably at least Hz. A film forming apparatus for evaporating the material in the container and depositing evaporated particles on a support, the container, a convex portion formed in the container, and an evaporation means for evaporating the material in the container And a vibration applying means for applying vibration to the container.

In particular, a film forming apparatus for evaporating a material in a container and depositing evaporated particles on a support, wherein the container, a convex portion formed in the container, and the material in the container are evaporated. This is achieved by a film forming apparatus comprising an evaporation means and a vibration applying means for applying vibration when the container is cooled. In this film forming apparatus, it is preferable that the vibration is 20 kHz or more.

When the alloy film is formed by using the above technique, since the material in the container (crucible) is uniform, particles having a uniform composition evaporate immediately after the start of evaporation. Therefore, it is possible to efficiently form a film having a uniform composition.

[0012]

1 and 2 show an embodiment of a film forming apparatus (manufacturing apparatus for a magnetic recording medium) according to the present invention. FIG. 1 is a schematic view of the whole, and FIG. 2 is a schematic view of essential parts. Is. 1 in each figure
Is a vacuum container, 2 is a turbo pump, 3 is a rotary pump,
4 is a non-magnetic support (for example, polyester such as PET, polyamide, polyimide, polysulfone, polycarbonate, olefin resin such as polypropylene,
Polymer side material such as cellulose resin and vinyl chloride resin) 6 supply side roll, 5 winding side roll of support 6, 7 cooling can, 8 crucible, 9 electron gun, 10 shielding plate , 11 are oxygen gas introduction pipes.

The structure of the crucible 8 is, as can be seen from FIG.
A plurality of triangular protrusions 12 are provided so as to protrude inside the bottom face portion, and a molten alloy in the crucible 8 (in the case of forming a back coat film, for example, a Cu-Al-Mn alloy,
Cu-Al-Fe alloy, Cu-Al-Ni alloy, Al-
The Si alloy 13) is guided by the convex portion 12 so that convection that is indicated by the arrow occurs, and the molten alloy 13 is easily made uniform. The constituent material of the crucible 8 is, for example, MgO, ZrO, BeO, Al ₂
O ₃ , Si ₃ N ₄ , BN, ThO ₂ , CaO, Si
Examples thereof include ceramics such as O ₂ and B ₄ C, and ceramics in which carbon-based fibers woven such as plain woven cloth and woven cloth are interposed. Among them, the preferred one is
It is a crucible made of B ₄ C or a ceramic crucible with a carbon fiber interposed.

Reference numeral 14 denotes an ultrasonic vibration generator provided at an appropriate position on the bottom surface of the crucible 8, and ultrasonic vibration of, for example, 50 kHz acts on the crucible 8. A method of manufacturing a magnetic recording medium using the apparatus configured as described above will be described. 10 ^-4 to 10 in the vacuum container 1
After evacuating to a vacuum degree of about ^-6 Torr, the magnetic metal (80% Co-20
% Ni) to evaporate 0.04 to 1 μm with respect to the support 6.
A metal thin film type magnetic recording medium is manufactured by evaporating a magnetic alloy having a thickness of, for example, 0.15 μm. still,
When forming the magnetic alloy thin film, it is preferable that oxygen is supplied from the oxygen gas introduction pipe 11 to the vapor deposition portion to oxidize the surface layer portion of the magnetic alloy thin film by forced oxidation to form a protective layer of an oxide film. . The thickness of the protective layer composed of this oxide film is about several tens of liters, and an oxide film of this thickness may be composed of natural oxidation. In some cases, no action is required.

After that, the winding-side roll 5 is taken out, and it is arranged on the support part of the supply-side roll so that the side on which the magnetic alloy thin film is formed contacts the cooling can 7, and the crucible 8 is made of Cu. -Al-X (where X is Mn, Fe, N
(1 or more selected from the group i) based alloy is filled, the inside of the vacuum container 1 is evacuated to a vacuum degree of about 10 ⁻⁴ to 10 ⁻⁶ Torr, and then electron beam heating is performed. The non-magnetic alloy in the crucible 8 is evaporated, and a non-magnetic alloy having a thickness of 0.04 to 1 μm, for example 0.1 μm, is vapor-deposited on the other surface side of the support 6. When forming this non-magnetic alloy thin film, oxygen is supplied from the oxygen gas introducing pipe 11 to the vapor deposition portion,
The surface layer of the non-magnetic alloy thin film is oxidized by the forced oxidation.

The amount of oxygen gas introduced from the oxygen gas introduction pipe 11 is about 25 ml / min of oxygen having a purity of 99.998%. Then, a perfluoropolyether (grade: FOMBLIN Z DIAC carboxyl group-modified, manufactured by Nippon Montedison Co., Ltd.) was added to a fluorine-inert liquid (Fluorinert, FC-84, manufactured by Sumitomo 3M Co., Ltd.) at 0.1.
% Of the coating composition diluted and dispersed by a die coating method so that the thickness after drying is about 20 Å and then coated on the surface of the magnetic alloy thin film, dried at 100 ° C, and slit into a predetermined width. I got a magnetic tape.

The relationship between the metal magnetic film provided on the support surface and the back coat film is preferably such that the direction of stress exerted by the metal magnetic film and the direction of stress exerted by the back coat film are the same. For example, when the stress caused by the metal magnetic film is of the tensile stress type, it is preferable to select the type and forming condition of the back coat film so that the stress caused by the back coat film is also of the tensile stress type. When both films are of the tensile stress type, the absolute value of the stress produced by the back coat film is designed to be larger than the stress produced by the metal magnetic film, whereby the curl rate is 0 to 0.
It is even more preferable to be 15%, especially 5 to 10%. Further, when the stress caused by the metal magnetic film is of the compressive stress type, it is preferable to select the type and forming condition of the back coat film so that the stress caused by the back coat film is also of the compressive stress type. Moreover, when both films are of the compressive stress type, the absolute value of the stress generated by the back coat film is designed to be smaller than the stress expressed by the metal magnetic film, whereby the curl rate is 0 to 15%. It is even more preferable to be 5 to 10%.

By the way, at the time of forming the above-mentioned non-magnetic alloy film, the film forming operation is stopped midway and the alloy in the crucible is cooled and cooled.
After solidification, the alloy in the crucible was irradiated again with an electron beam, and the film forming operation was restarted. 50 kH during this cooling and solidification
When ultrasonic vibration of z is applied to the crucible 8 (the present invention)
And those obtained by applying 50 kHz ultrasonic vibration to the crucible 8 when restarting the film forming operation (Comparative Example 1) and when not applying ultrasonic vibration to the crucible 8 (Comparative Example 2) For each of the deposited films, the results are shown in Table-1 and Table-2.

Table-1 (85at% Cu-9at% Al-1at% Mn-4at% Fe-1at% Ni alloy in crucible) Film composition prepared before stop (at%) Film prepared immediately after restart Composition (at%) Cu Al Mn Fe Ni O Cu Al Mn Fe Ni O Present invention 64.6 6.84 0.76 3.04 0.76 24 64.7 6.93 0.76 3.05 0.76 23.8 Comparative Example 1 Same as above 63.0 9.01 0.70 3.04 0.75 23.5 Comparative Example 2 same as above 60.9 11.24 0.71 3.00 0.75 23.4 Table-2 Warp of magnetic tape manufactured before stop Warp of magnetic tape manufactured immediately after resumption Present invention 5% 5% Comparative Example 1 Same as above 2% Comparative Example 2 Same as above -7% Comparative example 2 in which no vibration was applied
Although Comparative Example 1 in which ultrasonic vibration is applied is more preferable than the magnetic tape of Example 1, even in this case, it is understood that the magnetic tape obtained immediately after restarting is considerably different from the magnetic tape obtained before that. This indicates that the quality varies, and thus it is difficult to obtain a high quality magnetic recording medium.

On the other hand, the product obtained by the present invention in which ultrasonic vibration is applied during cooling and solidification has almost no difference in the characteristics before and after the restart, and therefore high-quality magnetism is obtained. This shows that the recording medium can be obtained with high yield.

[0021]

[Effect] A film having a uniform composition can be efficiently formed.

[Brief description of drawings]

FIG. 1 is a schematic view of an entire film forming apparatus according to the present invention.

FIG. 2 is a schematic view of a main part of a film forming apparatus according to the present invention.

FIG. 3 is a schematic view of a conventional magnetic recording medium manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 6 Support 7 Cooling can 8 Crucible 9 Electron gun 12 Convex portion 13 Molten alloy 14 Ultrasonic vibration generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Shiga 2606 Akabane, Kai-cho, Haga-gun, Tochigi Prefecture Kao Co., Ltd.

Claims (5)

[Claims] 1. A film forming method for evaporating a material in a container and depositing evaporated particles on a support, wherein a vibration is applied to the material in the container when the material in the container is cooled. Deposition method. 2. The film forming method according to claim 1, wherein the vibration is 20 kHz or more. 3. A film forming apparatus for evaporating a material in a container and depositing evaporated particles on a support, wherein the container, a convex portion formed in the container, and a material in the container are evaporated. A film forming apparatus comprising: evaporation means and vibration applying means for applying vibration to the container. 4. The film forming apparatus according to claim 3, wherein the vibration applying unit is configured to operate when cooling the material in the container. 5. The film forming apparatus according to claim 3, wherein the vibration applying unit is configured to apply a vibration of 20 kHz or more.