JPH10280156A - Plasma cvd device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma CVD device by which the productivity in the formation of protective coating film can be improved. SOLUTION: A protective coating film forming device 44 is provided with a plasma generating tube 46 having an emitting port 48 feeding gaseous substance forming a protective coating film and a film feeding/winding mechanism 13 having a freely rotatable roller 18 in which an electrode cylindrical face 16 is arranged closely to the emitting port 48. The emitting port 48 is opened along the running direction of a film so as to be formed within the film width, and all edges forming the emitting port 48 are crossed in the longitudinal direction of the film. In this way, even in the case the pressure of reactive gas in the plasma generating tube 46 is increased and the density of plasma formed on the edges of the emitting port 48 is made high, the protective coating film can be formed without thermally damaging the film 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma CVD apparatus for forming a protective film on a magnetic recording medium layer, and more particularly, to a plasma CVD apparatus for improving the productivity of forming a protective film. Things.

[0002]

2. Description of the Related Art As a magnetic recording medium such as a magnetic tape, a coating type magnetic recording medium in which a magnetic paint is applied on a non-magnetic material such as a film and dried is widely used. The magnetic paint is obtained by dispersing a powder magnetic paint such as an oxide magnetic powder or an alloy magnetic powder in an organic binder such as a vinyl chloride-vinyl acetate copolymer, a polyester resin, or a urethane resin. In recent years, a high-density magnetic recording medium capable of performing high-density magnetic recording has been demanded, and a Co—Ni alloy, a Co—Cr alloy has been formed by thin film forming means such as plating, vacuum evaporation, sputtering, and ion plating. A magnetic recording medium of a so-called metal magnetic thin film type, in which a ferromagnetic metal material such as an alloy or cobalt oxide made of Co—O is directly formed on a film, has attracted attention. A magnetic recording medium of a metal magnetic thin film type (hereinafter simply referred to as a magnetic recording medium or a medium for simplicity) is excellent in (1) in terms of coercive force and squareness, and (2) it is possible to reduce the thickness of a magnetic layer. Yes, (3)
It has a number of advantages such as a small amount of wear due to recording demagnetization and reproduction, (4) excellent electromagnetic conversion characteristics at short wavelengths, and (5) it is possible to increase the packing density of magnetic materials. I have.

[0003] Magnetic recording media tend to be more and more dense, and accordingly, flattening of the surface is required.
Meanwhile, when the medium is flattened, the frictional force between the magnetic recording head and the medium increases, and the shear force acting on the medium increases. For this reason, it is necessary to improve the durability of the medium, and as a countermeasure, a protective film is often formed on the surface of the medium.

The protective film is mainly a carbon film, a diamond-like carbon film (hereinafter, referred to as a DLC film), a quartz glass (SiO ₂ ) film, and a zirconia (ZrO ₂ ) film. Has been These protective films are formed by sputtering or CVD (Chemic).
Although the film is formed by the Al Vapor Deposition method, the CVD method is superior in terms of the film forming speed. Therefore, the protective film is often formed by the plasma CVD method. In addition, as a discharge method at the time of film formation, there are many DC (direct current) discharge methods which have a simple apparatus configuration and facilitate temperature control at the time of film formation.

FIGS. 4 (a) and 4 (b) are a side sectional view and a partially enlarged plan view taken along line II, respectively, showing the structure of a conventional plasma CVD apparatus for forming a protective film on a film. is there. The conventional plasma CVD apparatus 10 includes a film feeding / rewinding mechanism 13 for feeding and winding the film 12 at a constant speed, and a film feeding / rewinding mechanism 13 disposed below and close to the film feeding / rewinding mechanism 13. A plasma generation tube 14 is provided for supplying a gas (hereinafter, referred to as a plasma gas) obtained by converting a reactive gas for forming a protective film into a plasma toward the film formation surface.

The film feeding / rewinding mechanism 13 includes a rotatable cylindrical roller 18 having electrodes formed all around the cylindrical surface 16, a roll 26 for supporting a film wound in a roller shape, and a protective film. And a take-up roller 22 that winds up the film on which the film is formed, and rotates the roller 18 while bringing the film into surface contact with the electrode cylindrical surface 16 on the surface opposite to the surface on which the protective film is formed. And a mechanism for running the film at a constant speed in the longitudinal direction.

The plasma generating tube 14 is formed as a cylindrical body and has an inlet 20 for introducing a reaction gas at one end of the cylindrical body. Further, a discharge port 24 facing the electrode cylindrical surface 16 of the roller 18 and discharging the plasma-converted reaction gas to the surface on which the film is formed is provided at the other end of the cylindrical body.
The material of the tubular body is electrically insulating. The plasma generating tube 14 further includes an electrode 30 between the inlet 20 and the outlet 24 for converting the reaction gas introduced from the inlet 20 into plasma. A DC power supply 34 for supplying a voltage is connected to the electrode 30. The discharge port 24 is plasma CVD
When viewed from the side of the device 10, as shown in FIG.
The roller 18 has a concave arc shape corresponding to the electrode cylindrical surface 16 of the roller 18 and is close to the cylindrical surface 16. The outlet 24 is
In the plan view seen from the arrow II, it is rectangular as shown in FIG. The plasma CVD apparatus 10 further includes a chamber 38 for accommodating the film feeding mechanism 13 and the plasma generator 14, and an exhaust system 40 for evacuating the chamber 38 by vacuum.

In order to form a protective film on a film-forming surface using a conventional plasma CVD apparatus 10, a roller-like
The film 12 on which the protective film is not formed and wound so that the center hole diameter is equal to the diameter of the roll 26 is
Set to 6. Then, the film is pulled out, the film surface is held by the electrode cylindrical surface 16 such that the film deposition surface faces the discharge port 24, and the film end is hooked to the winding roll 22. On the deposition surface of the film 12,
A magnetic recording medium layer is formed. Next, chamber 3
8 is evacuated by the exhaust system 40 to make the inside of the chamber 38 a predetermined pressure. Next, the reaction gas is supplied to the plasma generation tube 1.
4, the film 12 is fed at a predetermined flow rate, and the winding roll 22 is rotated to feed / wind the film 12 at a constant speed.
A DC voltage is applied to the electrode 30 by the C power source 34 to generate a plasma gas, and a protective film is formed on the film-formed surface by the plasma CVD method.

[0009]

By the way, in the conventional plasma CVD apparatus, when the film feeding speed is increased to increase the productivity, the gas pressure of the reaction gas is increased.
It is necessary to increase the deposition rate of the protective film. However, when the film is formed at a reaction gas pressure of 20 Pa or more, damage such as wrinkles occurs in the film, and there is a problem that productivity cannot be increased. In view of the circumstances as described above, an object of the present invention is to provide a plasma CVD apparatus capable of improving the productivity of forming a protective film.

[0010]

According to the present inventors, the discharge port 24 of the plasma generating tube 14 has a rectangular shape as shown in FIG. Outlet 24
It has been noted that a part of the edge forming is an edge (hereinafter, referred to as a parallel edge) 42 formed in parallel with the film longitudinal direction, that is, the film running direction U. Furthermore, when forming the protective film on the film, it was noted that plasma sheaths 43a and 43b were formed on the parallel edge 42 and the other edge 41, respectively. The portion of the film deposition surface located on the parallel edge 42 is the discharge port 2
It was also noted that, during the process of passing over the sample No. 4, it was always in contact with the plasma sheath 43 a, while it was in contact with the plasma sheath 43 b on the film deposition surface for a moment. When the gas pressure of the reaction gas is high, the plasma density in the sheath increases, and as a result, a film deposition surface portion (hereinafter, referred to as a portion) in contact with the plasma sheath 43a.
(Referred to as a film contact surface portion) was found to have damage such as wrinkles due to thermal deformation of the film. The present inventor has paid attention to the fact that the film thickness of the protective film does not need to be uniform near the edge of the protective film, and by forming the discharge port 24 only from the edge that is not parallel to the film running direction U, the film The present inventors have conceived to greatly reduce the maximum time of contact with the sheath per unit area at the contact surface, and have completed the present invention.

In order to achieve the above object, a plasma CVD apparatus according to the present invention is a plasma CVD apparatus for continuously forming a protective film in a longitudinal direction on a magnetic recording medium layer formed on a tape-like film by a plasma CVD method. A CVD apparatus having a rotatable cylindrical roller having electrodes over the entire circumference of a cylindrical surface, and bringing the film into surface contact with the electrode cylindrical surface on the surface opposite to the surface on which the protective film is to be formed. Rotate
A film feeding mechanism configured to allow the film to travel at a constant speed in the longitudinal direction, and an inlet formed as a cylindrical body and introducing a reactive gas for forming a protective film is provided at one end of the cylindrical body with a roller. A discharge port, which faces the electrode cylindrical surface and discharges a plasma-formed reaction gas to the surface on which the film is to be formed, is provided at the other end of the cylindrical body. A plasma generator having an electrode for converting gas into plasma between an inlet and an outlet, a film feeding mechanism, and a plasma having an emission port arranged close to an electrode cylindrical surface of a roller of the film feeding mechanism. A chamber accommodating the generator and the discharge port is opened along the running direction of the film, the projection surface of the discharge port projected along the longitudinal direction of the cylindrical body is located in the film running surface, And open all around the outlet opening Edge is characterized by intersecting the traveling direction of the film.

In the present specification, a curved edge such as an arc shape is interpreted as intersecting in the longitudinal direction of the film. The direction of the discharge port is not limited to any direction, and may be in any of up, down, left, and right directions. The film is, for example, polyester, polyamide or polyimide. The reaction gas introduced into the plasma generator for forming the protective film is generally a hydrocarbon-based gas.

The magnetic recording medium layer formed on the surface on which the film is formed is made of a metal containing a ferromagnetic metal material, for example, a ferromagnetic metal having a single composition such as Fe, Co, Ni, or the like. Co, Co-O, Fe-Co-Ni, Fe-
Cu, Co-Cu, Co-Au, Co-Pt, Mn-B
i, Mn-Al, Fe-Cr, Co-Cr, Ni-C
r, Fe-Co-Cr, Co-Ni-Cr, Fe-Co
-A ferromagnetic alloy such as Ni-Cr. The magnetic recording medium layer may be composed of a single layer film or a multilayer film. Between the film and the magnetic recording medium layer, a layer having a lubricant or an intermediate layer for improving adhesion or controlling coercive force may be formed. When the magnetic recording medium layer is composed of a multilayer film, an intermediate layer similar to the above may be formed between the films. Further, an oxide layer may be formed on the surface of the magnetic recording medium layer for improving corrosion resistance. The magnetic recording medium is, for example, a PVD (Physical Deposition) method such as a vacuum evaporation method, an ion plating method, and a sputtering method.
It is formed on the surface on which the film is to be formed by a vapor deposition method.

According to the present invention, at the film contact surface portion,
Since the maximum time in contact with the plasma sheath per unit area is significantly reduced as compared to the conventional method, even if the plasma density is increased by increasing the reaction gas pressure at the time of forming the protective film to about 100 Pa, There is no thermal damage such as wrinkles on the film. Therefore, the deposition rate of the protective film can be made much higher than before, and the productivity is improved.

[0015] Preferably, the projection surface of the discharge port is any of a trapezoid, a parallelogram, and a figure in which at least an opening edge extending in the running direction of the film is a curved side. This allows
The time during which the film deposition surface is formed with the gaseous substance from the discharge port is uniform except near the edges at both ends in the film width direction, so that the thickness of the protective film is also uniform.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment This embodiment is an embodiment of a plasma CVD apparatus according to the present invention. 1A and 1B are a side view and an arrow I, respectively, showing the configuration of the plasma CVD apparatus of the present embodiment.
FIG. 2 is an enlarged partial plan view as viewed from I-II. In the plasma CVD apparatus 44 of the present embodiment, the shape of the discharge port 48 of the plasma generating tube 46 is different from that of the discharge port 24 of the conventional plasma CVD apparatus 10. In FIG. 1, the same components as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The electrode 30 has a wire mesh shape, easily allows a reaction gas to pass therethrough, can generate a uniform electric field over the entire surface of the electrode, and has flexibility. The material of the electrode 30 is, for example, copper or gold. The DC power supply 34 can apply a DC voltage of 0.5 kV to 2 kV to the electrode 30. The diameter of the roller 18 is 1 m. Between the roller 18 and the take-up roll 22, there is provided a rod-shaped support 45a for regulating the traveling path of the film 12, and between the roller 18 and the roll 26, a similar support 45b is provided. Have been.

A plan view of the edge shape of the discharge port 48 is shown in FIG.
As shown in (b), a trapezoid including a center line of the film 12 and being symmetrical with respect to a center plane 53 orthogonal to the film 12,
An edge 52 having a top side 50a and a bottom side 50b orthogonal to the running direction U of the film 12, and corresponding to the oblique side of a trapezoid.
a and b intersect with the running direction U of the film 12.
The length l ₁ of the top side 50a is 50 cm, the length l ₂ of the bottom side 50b is 60 cm, and on both sides of the center plane 53, the difference in length between the bottom side 50b and the top side 50a is l ₃ = 5 cm. Is formed. Further, the distance (trapezoid height) h between the top side 50a and the bottom side 50b is 40 cm, but may be 30 cm.

Using a plasma CVD apparatus 44, a width of 60
A method of forming a protective film on the film-forming surface of the film 12 having a thickness of 12 cm will be described below. In this embodiment, a single-layer magnetic recording medium layer is previously formed on the film deposition surface by oblique evaporation, which is evaporated in an oblique direction. The materials and thicknesses of the film and the magnetic recording medium layer are shown below. Film material: PET (polyethylene terephthalate) Film thickness: 10 μm Material of magnetic recording medium layer: Co (cobalt) 80%, Ni
(Nickel) 20% Film thickness of magnetic recording medium layer: 200 nm The film forming conditions of the magnetic recording medium layer are shown below. Incident angle: 45 ° to 90 ° Gas used during film formation: oxygen gas Vacuum degree during film formation: 2 × 10 ⁻² Pa

First, the film 12 on which the protective film was not formed was set in the film feeding / winding mechanism 13 in the same manner as in the prior art. Next, the chamber 38 is connected to the exhaust system 4.
Vacuum suction was performed using 0, and the pressure in the chamber 38 was reduced to a predetermined pressure. Next, ethylene is introduced into the plasma generating tube 14 as a reaction gas for forming a protective film, and the film feeding / winding speed is set to a constant speed of 13 m / min, which is much higher than the conventional speed. While continuously supplying the film deposition surface onto the discharge port 48 by rotating the
A DC voltage was supplied to the electrode 30 from the C power supply 34, and a DLC film was formed on the film formation surface by a plasma CVD method. The film forming conditions are shown below. Reaction gas introduced into the plasma generating tube 46: Reactant gas pressure in the ethylene chamber 38: 50Pa Reaction gas introduction flow rate: 1.2 SLM Voltage applied to the electrode 30: DC 1.0kV DLC film thickness: 10nm DLC film thickness After film formation, thermal damage such as wrinkles did not occur in the film.

If l ₃ is shorter than 5 cm, an edge slightly parallel to the running direction U of the film is formed, and the film may be damaged by the plasma sheath during the formation of the protective film.

In this embodiment, since the DLC film is formed on the surface on which the film is formed by increasing the reaction gas pressure in the chamber 38, the film forming speed of the protective film is high. Can be increased in winding speed. Therefore, the productivity of the protective film is much higher than before. Further, an upper side 50a and a lower side 50b forming the discharge port 48 are formed.
Is constant, the thickness of the protective film is uniform except in the vicinity of the edge of the protective film.

FIG. 2 is an enlarged plan view showing the discharge port of the plasma generator 46 as viewed from the direction of arrows II-II, and the discharge port 48 has an arc-shaped edge 5 with a concave inside.
A substantially quadrangular discharge port 55 having 6a and 6b instead of the hypotenuse 52 may be used. In this case, the film is formed on both sides of the center plane 53 of the discharge port 55 at l ₃ = 5 cm inside each of the longest edge points 58a and 58b with respect to the center plane 53. The opening width d in the longitudinal direction is a uniform value of 40 cm, which is the same as h. Since the plasma CVD apparatus 44 includes the emission port 55, the same effect as having the emission port 48 can be obtained.

FIG. 3 is an enlarged plan view showing the discharge port of the plasma generator 46 as viewed from the direction of arrows II-II, and the plane shapes of the discharge ports 48 are parallel to each other in the film width direction. The outlet 62 may be a parallelogram having sides. In this case, the central surface 53 of the outlet 62
On each side of each of the longest edge points 6 with respect to the center plane 53
The opening width d in the longitudinal direction of the film in the outlet region formed on the inner side of l ₃ = 5 cm from each of 6a and b is:
As in the case of the discharge port 55, it is a uniform value of 40 cm, the same as h.
By providing the plasma CVD apparatus 44 with the discharge port 62, the same effect as having the discharge port 48 can be obtained.

[0024]

According to the present invention, the discharge port of the plasma generator for continuously forming the protective film on the magnetic recording medium layer formed on the tape-like film in the longitudinal direction is provided in the running direction of the film. Along, the edges forming an opening within the film width and forming the outlet are all intersecting in the longitudinal direction of the film. As a result, the maximum length of time in contact with the sheath per unit area in the film deposition surface portion in contact with the plasma sheath formed at the edge of the discharge port is significantly reduced as compared with the conventional case. . Therefore, even if the reaction gas pressure at the time of forming the protective film is increased, and even if the plasma density in the sheath is increased, it is possible to avoid the occurrence of thermal damage such as wrinkles on the film. it can. Therefore, the feeding speed of the film can be increased, and the productivity is improved. Preferably, the opening width in the longitudinal direction of the film is uniform except near the edges at both ends in the film width direction. Accordingly, the time during which the film deposition surface is formed by the gaseous substance from the discharge port is uniform except for the vicinity of the edges at both ends in the film width direction.
The thickness of the protective film is also uniform.

[Brief description of the drawings]

FIGS. 1A and 1B are a side view showing a configuration of a plasma CVD apparatus according to an embodiment, and an arrow II, respectively.
FIG. 2 is an enlarged plan view of a discharge port of a plasma generation tube viewed from −II.

FIG. 2 is an enlarged partial plan view of a discharge port of another plasma generating tube of the embodiment.

FIG. 3 is an enlarged partial plan view of a discharge port of another plasma generating tube of the embodiment.

4 (a) and 4 (b) are a side view showing a configuration of a conventional plasma CVD apparatus, and an arrow II, respectively.
FIG. 3 is an enlarged plan view of a discharge port of a plasma generation tube as viewed from above.

[Explanation of symbols]

10: Plasma CVD device, 12: Film, 13
... Film feeding / winding mechanism, 14 Plasma generating tube, 16 Electrode cylindrical surface, 18 Roller, 20
Gas inlet, 22 ... take-up roll, 24 ... discharge outlet,
26: roll, 30: electrode, 34: DC power supply, 3
8 ... chamber and 40 ... exhaust system, 41 ... rim, 4
2 ... parallel edge, 43a, b ... plasma sheath, 44 ...
... Plasma CVD apparatus, 45a, b ... Support, 46 ...
... Plasma generating tube, 48 ... Emission port, 50a ...
50b ... bottom side, 52a, b ... edge (oblique side), 53 ...
Center plane, 55 ... outlet, 56a, b ... edge, 58a,
b ... edge, 62 ... outlet, 66a, b ... edge.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Atsuhiro Abe 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (2)

[Claims] 1. A plasma CVD apparatus for continuously forming a protective film in a longitudinal direction on a magnetic recording medium layer formed on a tape-like film by a plasma CVD method, comprising a rotary member having electrodes over the entire circumference of a cylindrical surface. It has a free-form cylindrical roller and rotates the roller while keeping the film in surface contact with the electrode cylindrical surface on the surface opposite to the surface on which the protective film is formed, so that the film runs at a constant speed in the longitudinal direction. A film feeding mechanism, which is formed as a cylindrical body, has an inlet for introducing a reactive gas for forming a protective film at one end of the cylindrical body, facing the electrode cylindrical surface of the roller, and is formed into plasma. A discharge port for discharging the reaction gas discharged to the film-forming surface of the film is provided at the other end of the tubular body, and an electrode for discharging the reaction gas introduced from the introduction port into plasma is disposed opposite the electrode of the roller. Plasma generation between outlet And a chamber for accommodating a film feed mechanism, and a plasma generator in which an emission port is arranged in close proximity to an electrode cylindrical surface of a roller of the film supply mechanism. The projection surface of the discharge port projected along the longitudinal direction of the tubular body is located in the film running surface, and the opening edge crosses the running direction of the film over the entire circumference of the opening of the discharge port. A plasma CVD apparatus. 2. The plasma according to claim 1, wherein the projection surface of the discharge port is any of a trapezoid, a parallelogram, and a figure in which an opening edge extending at least in the running direction of the film is a curved side. CVD equipment.