JPH08319567A - Film forming device and production of magnetic recording medium using the same - Google Patents

Abstract

PURPOSE: To produce a magnetic recording medium excellent in durability, small in the secular change of magnetic properties and high in reliability by forming a thin film having high nardness and excellent durability. CONSTITUTION: In a vacuum chamber 1, a film 2 obtd. by forming a metal magnetic film on a nonmagnetic supporting body is run on the circumferential face of a cylindrical can 5, it is formed into a circular arc shape so as to regulate the distance with the circumferential face of the cylindrical can 5 to a certain one, and while prescribed voltage is applied to an electrode 10 having plural vacancies, a prescribed gas is fed toward the film 2 via the vacancies of the electrode 10. By a chemical vapor growth method, a protective film constituted of a diamond-like carbon film is formed on the film 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus to which a chemical vapor deposition (hereinafter referred to as CVD) method is applied, and a magnetic film for forming a protective film using the film forming apparatus. The present invention relates to a recording medium manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a powder magnetic material such as an oxide magnetic powder or an alloy magnetic powder is coated on a non-magnetic support with a vinyl chloride-vinyl acetate copolymer, polyester resin, urethane resin, A so-called coating type magnetic recording medium, which is prepared by coating and drying a magnetic coating material dispersed in an organic binder such as a polyurethane resin, is widely used.

On the other hand, with the increasing demand for high-density recording, Co--Ni alloys, Co--Cr alloys, Co--
A so-called metal magnetic thin film type magnetic recording medium in which a metal magnetic material such as O is directly deposited on a non-magnetic support by plating or vacuum thin film forming means (vacuum deposition method, sputtering method, ion plating method, etc.) It has been proposed and attracts attention.

This metal magnetic thin film type magnetic recording medium is excellent not only in coercive force and squareness ratio but also in electromagnetic conversion characteristics at short wavelengths, and the magnetic layer can be extremely thin,
There are many advantages such as remarkably small thickness loss during recording demagnetization and reproduction, and higher packing density of the magnetic material because there is no need to mix the binder, which is a non-magnetic material, into the magnetic layer. Have

Further, in order to improve the electromagnetic conversion characteristics of this kind of magnetic recording medium and to obtain a larger output, the magnetic layer is obliquely vapor-deposited when forming the magnetic layer of the magnetic recording medium. The so-called oblique vapor deposition has been proposed and put to practical use.

By the way, it is said that a magnetic recording medium having a metal magnetic thin film formed on a non-magnetic support as described above has a problem in durability and rust resistance. A protective film is formed on the surface of a metal magnetic thin film. As the protective film, it has been considered to deposit carbon, silicon oxide, various nitrides, ceramics, etc. by a sputtering method, but in recent years, since the film forming speed is slow and the productivity is low, the CVD method has been used.
Film formation by the method is being studied.

To form a protective film by the CVD method,
A plasma CVD apparatus as shown in FIG. 2 may be used. In this plasma CVD apparatus, a vacuum chamber 101 is evacuated by a vacuum evacuation system 108 so that the inside is in a vacuum state.
Inside, a feed roll 103 and a take-up roll 104 are arranged. From the feed roll 103 toward the take-up roll 104, a metal magnetic thin film is formed on the non-magnetic support as described above. The film 102 is sequentially run.

A cylindrical can 105 having a diameter larger than that of each of the rolls 103 and 104 is arranged in the middle of the traveling of the film 102 from the feed roll 103 to the take-up roll 104.

Therefore, the film 102 is sequentially fed from the feed roll 103, moved and run along the peripheral surface of the cylindrical can 105, and is further wound on the winding roll 104 in sequence.

Further, between the feed roll 103 and the cylindrical can 105, and between the cylindrical can 105 and the take-up roll 104, the rolls 103, 104 are provided.
Smaller diameter guide rolls 106 and 107 are respectively arranged, and the feed roll 103 to the cylindrical can 10 are arranged.
5. From the cylindrical can 105 to the take-up roll 104
A predetermined tension is applied to the film 102 that travels for a long time so that the film 102 can travel smoothly.

A bias voltage can be applied to the cylindrical can 105 by a DC power source. Also,
Below the cylindrical can 105, the cylindrical can 105
A gas reaction tube 109 having an opening curved to be substantially parallel to the peripheral surface of is provided, and a mesh-shaped electrode 110 made of gold is arranged inside the gas reaction tube 109. A gas supply pipe 111 for supplying gas into the gas reaction pipe 109 is connected to the gas reaction pipe 109.

Therefore, when the source gas is supplied from the gas supply pipe 111 in a state where the bias voltage is applied to the cylindrical can 105 and the predetermined DC voltage is applied to the electrode 110, the material gas passes through the mesh of the electrode 110 and becomes a predetermined amount. A protective film is formed by causing a reaction and continuously depositing the decomposition product on the surface of the film 102 traveling on the peripheral surface of the cylindrical can 105.

[0013]

By the way, in the above-mentioned plasma CVD apparatus, in order to efficiently form the protective film, the electrode 110 is brought close to the cylindrical can 105 and the film traveling on the peripheral surface of the cylindrical can 105. It is considered effective to increase the electric field strength near the surface of 102.

However, in this plasma CVD apparatus, since the main surface of the electrode 110 is a horizontal surface, the film 102 runs on the peripheral surface of the cylindrical can 105 while changing the distance from the electrode 110, and therefore, Electrode 1
The closer 10 is to the cylindrical can 105, the more film 10
The ratio of the shortest distance to the longest distance between the electrode 2 and the electrode 110 becomes large, and the change rate of the electric field strength near the surface of the film 102 becomes large.

When the electric field strength in the vicinity of the surface of the film 102 greatly changes in this way, a protective film formed with a different electric field strength is deposited at the same point on the film, so that the protection is performed. The film quality of the film changes in the film thickness direction. It is difficult to give such a protective film sufficient strength.

Therefore, the present invention has been proposed in view of such conventional circumstances, and an object thereof is to provide a film forming apparatus capable of forming a thin film having a uniform film quality in the film thickness direction. Another object of the present invention is to provide a method of manufacturing a magnetic recording medium for forming a protective film having sufficient strength by using this film forming apparatus.

[0017]

A film forming apparatus according to the present invention comprises a cylindrical can for moving a film forming object in a vacuum chamber,
The electrode is formed in an arc shape so that the distance from the peripheral surface of the cylindrical can is constant, and has a plurality of holes, and a predetermined gas is formed through the holes of the electrode. A gas supply port for supplying gas toward the film body is provided, and a desired thin film is formed on the film formation target by the CVD method.

When this film forming apparatus is applied to the film formation of the protective film in the manufacturing process of the magnetic recording medium, the film forming object is
It is a film in which a metal magnetic thin film is formed on a non-magnetic support, and the desired thin film serves as a protective film.

That is, in the method of manufacturing a magnetic recording medium according to the present invention, a film in which a metal magnetic thin film is formed on a non-magnetic support is run on the peripheral surface of a cylindrical can in a vacuum chamber,
While applying a predetermined voltage to an electrode that is arcuate and has a plurality of holes so that the distance from the circumferential surface of the cylindrical can is constant, a predetermined gas is applied to the holes of the electrode. To the film through the CVD method,
A protective film is formed on the film.

Here, it is preferable that the electrodes are provided with holes in a mesh shape. The material of this electrode is
Examples include copper, brass, various SUS steels, gold and the like.

The distance between the cylindrical can and the electrode is 20 mm to
It is preferably 300 mm. If it is less than 20 mm, abnormal discharge is likely to occur, and the film running on the peripheral surface of the cylindrical can is likely to lose heat.
On the other hand, if it is larger than 300 mm, the effect of ions at the time of film formation is weakened, and the gas reaction tube itself becomes large.

As the protective film, any conventionally known film may be formed, but a diamond-like carbon film is preferably formed.

The present invention is applied when manufacturing a so-called metal magnetic thin film type magnetic recording medium, but the non-magnetic support and the material of the metal magnetic thin film constituting the magnetic recording medium are not particularly limited.

As the non-magnetic support, polyesters,
Polymer substrates formed of polymer materials typified by polyolefins, celluloses, vinyls, polyimides, polycarbonates, metal substrates made of aluminum alloys and titanium alloys, ceramic substrates such as aluminum glass, and glass Examples of the substrate include a substrate, and the shape thereof is not particularly limited, but a tape shape is preferable because the protective film is formed by traveling on the peripheral surface of the cylindrical can. In this case, polyethylene terephthalate film,
Polyethylene naphthalate film, aramid film and the like are preferable. Also, these films include
A filler may be internally added to control the surface roughness, or a layer for controlling the surface roughness may be formed on the surface.

As the metal magnetic thin film, any metal magnetic material usually used for a magnetic recording medium of metal magnetic thin film type can be used. For example, Fe, Co, Ni
Ferromagnetic metals such as Fe-Co, Fe-Ni, Co-N
i, Fe-Co-Ni, Fe-Co-B, Fe-Ni-
B, Fe-Cu, Co-Cu, Co-Au, Co-P
t, Mn-Bi, Mn-Al, Fe-Cr, Co-C
r, Ni-Cr, Fe-Co-Cr, Co-Ni-C
r, Co-Ni-Pt, Fe-Co-Ni-Cr, Fe
-Co-Ni-B or other magnetic alloy thin film made of a ferromagnetic alloy for in-plane magnetization recording, Co-Cr alloy thin film, Co-O
Examples thereof include metal magnetic thin films for perpendicular magnetization recording such as system thin films.

These metal magnetic materials include a vacuum vapor deposition method of evaporating a ferromagnetic metal magnetic material under vacuum to deposit it on a support, an ion plating method of evaporating a ferromagnetic metal material in a discharge, and argon. A thin film is formed by a so-called PVD technique such as a sputtering method in which atoms on the target surface are knocked out by argon ions generated through a glow discharge in an atmosphere containing the main component. The magnetic layer may be either a single layer film or a multi-layer film of a metal magnetic thin film formed by these methods. In order to improve the adhesive force between layers and control the coercive force between the non-magnetic support and the metal magnetic thin film, or between the metal magnetic thin films when the metal magnetic thin film is a multilayer film. A base layer or an intermediate layer may be provided. Further, the vicinity of the surface of these metal magnetic thin films may be an oxide layer for the purpose of improving corrosion resistance and the like.

Particularly, in the case of a metal magnetic thin film for in-plane magnetization recording, Bi, Sb, Pb, Sn and G are previously formed on a non-magnetic support.
A base film of a low melting point non-magnetic material such as a, In, Ge, Si, Ti is formed in advance, and a metallic magnetic material is vapor-deposited or sputtered from the vertical direction to diffuse the low melting point non-magnetic material into the metallic magnetic thin film. However, the orientation may be eliminated to secure the in-plane isotropy and improve the coercive force.

Further, a back coat layer is formed on the surface of the non-magnetic support opposite to the side on which the metal magnetic thin film is formed, or a top coat made of a lubricant, an extreme pressure agent or the like is further formed on the protective film. The layer may be applied. As a material used for these layers, any conventionally known material can be used. For example, the back coat layer is a non-magnetic layer in which a non-magnetic powder having an antistatic effect and a friction reducing effect, such as carbon black formed in a normal magnetic recording medium, is dispersed in a binder. Good.

[0029]

In the film forming apparatus according to the present invention, since the distance between the peripheral surface of the cylindrical can and the electrode is constant, the electric field strength near the surface of the film traveling on the peripheral surface of the cylindrical can is also constant. . Further, since the predetermined gas is supplied to the discharge space between the electrode and the film through the plurality of holes provided in the electrode, the concentration of the gas in the discharge space can be made uniform.

Therefore, while the film traveling on the peripheral surface of the cylindrical can passes through the region facing the electrode, the film is always formed under the same condition at a predetermined point of the film. Therefore, the quality of the formed thin film is
It becomes uniform in the film thickness direction and has excellent strength.

[0031]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Example 1 In this example, a plasma CVD apparatus to which the present invention is applied will be described.

As shown in FIG. 1, this plasma CV
In the device D, a feed roll 3 and a take-up roll 4 are arranged in a vacuum chamber 1 which is evacuated by a vacuum exhaust system 8 and has a vacuum inside. As described above, the film 2 in which the metal magnetic thin film is formed on the non-magnetic support is sequentially run toward the above.

These feed roll 3 to take-up roll 4
A cylindrical can 5 having a diameter larger than that of each of the rolls 3 and 4 is disposed in the middle of the side where the film 2 runs.

The cylindrical can 5 is provided so as to pull out the film 2 downward in the drawing. A cooling device (not shown) is provided inside the cylindrical can 5 so as to suppress deformation of the film 2 due to a temperature rise, and a bias voltage is applied by a DC power source. You can do it.

The feed roll 3, the winding roll 4 and the cylindrical can 5 each have a cylindrical shape having a length substantially the same as the width of the film 2. Here, the diameter of the cylindrical can 5 is set to 60 cm.

Plasma CVD having the above structure
In the apparatus, the film 2 is sequentially fed out from the feed roll 3, moved and run along the peripheral surface of the cylindrical can 5, and further wound around the winding roll 4 in sequence.

Between the feed roll 3 and the cylindrical can 5, and between the cylindrical can 5 and the take-up roll 4.
And guide rolls 6 and 7 having a smaller diameter than the rolls 3 and 4, respectively, and run from the feed roll 3 to the cylindrical can 5 and from the cylindrical can 5 to the take-up roll 4. A predetermined tension is applied to the film 2 so that the film 2 runs smoothly.

Below the cylindrical can 5, a gas reaction tube 9 having an opening curved so as to be substantially parallel to the peripheral surface of the cylindrical can 5 is provided, and a mesh made of gold is provided inside the gas reaction tube 9. The electrodes 10 are arranged.

Here, the electrode 10 has a distance of 250 mm from the peripheral surface of the cylindrical can 5 at any point.
It is formed in an arc shape so that it is higher than the bias voltage applied to the cylindrical can 5 and is 500 V to 2000 V.
A voltage of V is applied.

The gas reaction tube 9 has substantially the same width as the cylindrical can 5 facing it, and here,
It is a rectangular parallelepiped having a height of 20 cm and a length of 10 cm in the running direction of the film 2. The gas reaction tube 9 is made of quartz tube Pyrex glass, plastic, or the like.

A gas supply pipe 11 for supplying gas into the gas reaction pipe 9 is connected to the gas reaction pipe 9.

Therefore, when the source gas is supplied from the gas supply pipe 11 with the bias voltage applied to the cylindrical can 5 and the predetermined DC voltage applied to the electrode 10, the electrode 1
A predetermined reaction is caused by passing through the 0 mesh, and the decomposition products are continuously deposited on the surface of the film 2 running on the peripheral surface of the cylindrical can 5.

Plasma CVD having the above structure
In the apparatus, since the distance between the peripheral surface of the cylindrical can 5 and the electrode 10 is constant, the electric field strength near the surface of the film 2 running on the peripheral surface of the cylindrical can 5 is constant. Therefore, the quality of the formed film becomes uniform in the film thickness direction.

Example 2 In this example, the plasma CVD apparatus described above is used,
A magnetic tape was produced by forming a protective film made of a diamond-like carbon film on a film obtained by forming a metal magnetic thin film on a non-magnetic support.

Specifically, first, for a polyethylene terephthalate (PET) film having a thickness of 10 μm, C
A metal magnetic thin film having a film thickness of 0.15 μm was formed by vacuum vapor deposition using o ₈₀ —Ni ₂₀ (numbers indicate composition ratio) as a vapor deposition source. The film forming conditions for the metal magnetic thin film are as follows.

Film forming conditions for metal magnetic thin film Incident angle of vapor deposition particles: 45 to 90 ° Amount of oxygen introduced: 3.3 × 10 ⁻⁶ m ³ / sec Vacuum degree during vapor deposition: 7 × 10 ⁻² Pa By partially oxidizing Co ₈₀ —Ni ₂₀ by introducing oxygen, the coercive force Hc of the metal magnetic thin film is 110 kA.
/ M and residual magnetic flux density Br were adjusted to 0.45T.

Then, the film 2 on which the metal magnetic thin film was formed in this manner was treated with the plasma CV shown in Example 1.
The cylindrical can 5 in device D was run at a speed of 3 m / min. Further, toluene was gasified and supplied from the gas supply pipe 11 into the gas reaction pipe 9 at a flow rate of 10 sccm, and the pressure in the vacuum chamber 1 was set to 10 Pa.

Then, by applying a bias voltage to the cylindrical can 5 and applying a DC voltage of 2 kV to the electrode 10 to perform glow discharge, the decomposition product of toluene is deposited on the surface of the running film 2. It was

As a result, a protective film made of a diamond-like carbon film was formed to a thickness of 10 nm on the surface of the metal magnetic thin film.

After that, the film on which the protective film was formed as described above was cut into a width of 8 mm to complete a magnetic tape, which was used as a sample tape of the example.

Comparative Example 1 For comparison, a protective film was formed using a conventional plasma CVD apparatus in which the distance between the peripheral surface of the cylindrical can and the electrode was not constant.

Specifically, as shown in FIG. 2, a plasma CVD apparatus having the same structure as in Example 1 was used, except that the electrode 110 was not curved and was horizontal. Then, in the same manner as in Example 2, the film 102 in which the metal magnetic thin film is formed on the non-magnetic support.
On the other hand, a protective film made of a diamond-like carbon film was formed to prepare a magnetic tape, and a sample tape of a comparative example was obtained.

Evaluation of Characteristics For each sample tape manufactured as described above,
The hardness (Hv), shuttle durability, and still durability of the protective film were examined.

Here, for the measurement of shuttle durability and still durability, an 8 mm video deck (manufactured by Sony Corporation, trade name CVD-1000) equipped with a sendust head having a track width of 20 μm was used. The shuttle durability was measured by recording a signal on a sample tape in an atmosphere of 20 ° C. and 60% RH, and measuring the output level after the sample tape was played back 1,000 times for 30 minutes, and the initial output level was 0d.
It was evaluated by converting the relative value as B. Also, the still durability is the still reproduction under the same atmosphere as above,
The time required for the reproduction output to decrease by 3 dB was evaluated.

On the other hand, regarding the hardness (Hv) of the protective film,
A silicon plate is run on each circumferential surface of the cylindrical cans 5 and 105 in the plasma CVD apparatus shown in FIGS. 1 and 2 instead of the films 2 and 102 in which a metal magnetic thin film is formed on a non-magnetic support. A protective film was formed in the same manner as in Example 2 and Comparative Example 1 except that the hardness was measured by an indentation method. The hardness of the protective film formed by the plasma CVD apparatus of FIG. 1 is defined as the hardness (Hv) of the protective film in the sample tape of the example, and the hardness of the protective film formed by the plasma CVD apparatus of FIG. The hardness was defined as the hardness (Hv) of the protective film in the sample tape of the comparative example. Table 1 shows the results.

[0057]

[Table 1]

From Table 1, the sample tapes of Examples have a large hardness (Hv) of the protective film and have sufficient shuttle durability and still durability. It can be seen that the hardness (Hv) is small and the shuttle durability and the still durability are also poor.

From this, when the electric field strength near the film surface is kept constant by keeping the distance between the film and the electrode constant, the film quality of the formed protective film becomes constant in the film thickness direction. It was found that a protective film having a high price and excellent durability can be obtained.

Although the film forming apparatus according to the present invention and the method for manufacturing a magnetic recording medium using the same have been described above, the present invention is not limited to the above-mentioned embodiments and does not depart from the gist of the present invention. Modifications and changes can be appropriately made within the range.
For example, the kind of the hydrocarbon compound gas introduced to form the protective film is not limited to toluene, and another gas may be added to the hydrocarbon compound gas. Further, the gas reaction tube 9 of the plasma CVD apparatus may be divided by a partition plate, and the gas of the hydrocarbon compound and the other gas may be supplied to the two spaces, respectively.

[0061]

As is clear from the above description, by using the film forming apparatus according to the present invention, a thin film having high hardness and excellent durability can be formed. Therefore, when the protective film is formed by this film forming apparatus, it is possible to manufacture a highly reliable magnetic recording medium having excellent durability and little change in magnetic characteristics over time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a plasma CVD apparatus.

FIG. 2 is a schematic diagram showing a configuration example of a conventional plasma CVD apparatus.

[Explanation of symbols]

 1 vacuum chamber 2 tape 5 cylindrical can 9 gas reaction tube 10 electrode 11 gas supply tube

Claims (4)

[Claims] 1. A vacuum chamber is provided with a cylindrical can in which a film-forming target is made to travel and an arcuate shape so that the distance between the cylindrical can and the peripheral surface of the cylindrical can is constant, and a plurality of holes are provided. And a gas supply port that supplies a predetermined gas toward the film formation target through the holes of the electrode, and is formed on the film formation target by chemical vapor deposition. A film forming apparatus for forming a desired thin film. 2. The film-forming target is a film in which a metal magnetic thin film is formed on a non-magnetic support, and the desired thin film is a protective film. Deposition apparatus. 3. In a vacuum chamber, a film in which a metal magnetic thin film is formed on a non-magnetic support is run on the peripheral surface of a cylindrical can, and an arc shape is formed so that the distance from the peripheral surface of the cylindrical can is constant. A predetermined gas is applied to the film through the holes of the electrode while applying a predetermined voltage to the electrode having a plurality of holes, and the chemical vapor deposition method is used. According to the method, a protective film is formed on the film, thereby manufacturing a magnetic recording medium. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein the protective film is a diamond-like carbon film.