JP3317054B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic metal thin film type magnetic recording medium used for audio / video equipment, computers, and the like, and more particularly to achieving high-dimensional compatibility between electromagnetic conversion characteristics and practical reliability. Method of manufacturing a magnetic recording medium in which a protective film and a lubricant layer are sequentially formed on a magnetic layer
It is about the law .

[0002]

2. Description of the Related Art In recent years, there has been a demand for a magnetic recording apparatus to have a large capacity, a high speed, a high image quality and a high sound quality, a small size and a light weight, and the like. Accordingly, it is indispensable to achieve high-density recording as a magnetic recording medium. Compared with a conventional coating-type magnetic recording medium in which a magnetic material is dispersed in a binder, the residual magnetic flux density (Br) of the magnetic layer And coercive force (Hc)
The development and commercialization of ferromagnetic metal thin film type magnetic recording media which can make the magnetic layer thinner and which is optimal for ultra-smoothing the surface of the magnetic layer are being actively conducted.

However, since the magnetic layer of the ferromagnetic metal thin film type magnetic recording medium has low hardness and is easily plastically deformed, when it comes into direct contact with the magnetic head of a VTR rotating at high speed, the magnetic layer is instantaneously worn and damaged, Metal adhesion is caused on the head sliding surface, and as a result, there arises a problem that durability is deteriorated (a recording / reproducing output is significantly reduced due to repeated running, and a still life is significantly reduced). Further, the surface of the magnetic layer has a problem that the oxide film is formed and protected, but the corrosion resistance in a high humidity environment is insufficient.

In order to improve the lubricity, abrasion resistance and corrosion resistance of a ferromagnetic metal thin film type magnetic recording medium, a base film having fine projections has been used.
It has been proposed to form a protective film or a fluorine-containing lubricant layer having both a slipperiness and a water-repellent effect on a magnetic layer. Especially for the protective film, in order to reduce the spacing loss between the magnetic layer and the magnetic head, it is necessary to set the thickness of the protective film to be thin, so that a diamond-like carbon film having high hardness and low wear resistance is formed on the magnetic layer. Many configurations have been proposed (for example, described in JP-A-61-210518 and JP-A-63-98824).

In Japanese Patent Application Laid-Open Nos. 1-245417 and 2-158909, a diamond-like carbon film is formed on a magnetic layer, and a lubricant layer (fluorine-containing fatty acid layer) is formed on the diamond-like carbon film. ) Is disclosed.

[0006] However, it is very difficult to provide a magnetic recording medium that satisfies traveling stability and durability sufficiently by using a conventional method, and various problems have arisen.

For example, when only a fluorinated lubricant layer is formed on a magnetic layer, the shear force can be reduced, but the hardness of the medium surface is low and the medium is liable to wear, so that the running stability is deteriorated and As a result, the still life is reduced.

When only a hard protective film (for example, a diamond-like carbon film) is formed on the magnetic layer, the protective film itself is brittlely broken by direct contact with the magnetic head of the VTR rotating at a high speed. This leads to a remarkable decrease in the still life, and it is not possible to ensure the stability of the reproduction output during repeated running.

Further, even when a high-hardness diamond-like carbon film and a lubricant layer are sequentially formed on the magnetic layer, the surface state of the diamond-like carbon film is chemically very inactive. Becomes insufficiently adhesive,
During recording / reproducing, there was a problem that seizure consisting of a lubricant component occurred on the head sliding surface, resulting in a remarkable decrease in output and long-term head clogging.

On the other hand, when a hard carbon film is formed on a magnetic layer, the adhesion (adhesion) between the magnetic layer and the hard carbon film is insufficient. After the hard carbon film partially peels off, durability,
Problems such as remarkable deterioration of weather resistance occurred.

Therefore, recently, in order to improve the adhesion between the protective film and the lubricant layer, a hard carbon protective film, a nitrogen-containing plasma polymerized film, and a lubricant layer containing a fluorinated carboxylic acid are provided on the ferromagnetic metal thin film. Configuration of forming sequentially (JP-A-2-12641)
No. 7), an organic polymer compound in which at least carbon atoms and nitrogen atoms are contained on a ferromagnetic metal thin film layer and the concentration of nitrogen atoms in the surface layer is at least 40 atom% with respect to the concentration of carbon atoms. In which a protective film layer is formed and a lubricant layer is formed on the protective film layer (Japanese Patent Laid-Open No. 62-5841).
No. 6), B or Ti or S on a ferromagnetic metal thin film.
After forming a hard carbon thin film containing i, a lubricant layer having a reactive group is continuously disposed by a vacuum evaporation method
184722), Mn, M on a magnetic metal thin film
After providing a protective film mainly composed of graphite-like carbon containing at least one selected from o, Nb, Ta, Ti, V and W, a lubricating layer mainly composed of an organic compound having a mercapto group is formed. Configuration (Japanese Unexamined Patent Publication No.
77312) and the like.

Japanese Patent Application Laid-Open No. 2-126418 discloses that
A configuration is disclosed in which a hard carbon film is formed on a ferromagnetic metal thin film, the surface of the hard carbon film is subjected to glow discharge treatment with ammonia gas, and a lubricant layer containing a fluorinated carboxylic acid is further formed.

On the other hand, Japanese Patent Publication No. 6-68834 discloses that
In order to improve the adhesion (adhesion) between the magnetic layer and the protective layer, a plasma polymerized layer having an oxygen / carbon (O / C) ratio of 0.30 or less on the surface in contact with the magnetic metal layer on the magnetic metal layer Is disclosed.

[0014]

However, even with the above-described structure, it is difficult to provide a magnetic recording medium having both excellent electromagnetic conversion characteristics and durability, and there are still many problems.

In the configuration in which the nitrogen-containing plasma polymerized film is formed at the interface between the hard carbon protective film and the lubricant layer, the running stability and durability are sufficiently satisfied because the hardness of the nitrogen-containing plasma polymerized film is low and easily worn. I can't let it. On the other hand, when the film thickness of the nitrogen-containing plasma polymerized film is set to be large in order to improve the wear resistance, the spacing loss between the magnetic layer and the magnetic head increases, and the electromagnetic conversion characteristics are deteriorated. I will.

In a configuration in which the concentration of nitrogen atoms in the protective film layer is set extremely high, or in a configuration in which a lubricant layer is formed on a protective film containing B, Ti, Si, metal, etc., the protective film and the lubricant However, the hardness of the protective film itself is reduced, but the durability such as still life is deteriorated.

In the structure in which the lubricant layer is formed after glow discharge treatment of the surface of the hard carbon protective film with ammonia gas, the surface of the hard carbon protective film is markedly affected by the impact of charged particles generated from ammonia which is a non-polymerizable gas. There was a problem that durability and weather resistance were significantly deteriorated due to being damaged.

Further, in each of the above-mentioned structures, the adhesion between the ferromagnetic metal thin film and the protective film is not sufficiently considered, so that the durability and the weather resistance are unexpectedly deteriorated.

On the other hand, when an interface on the side of the plasma polymerized layer in contact with the magnetic layer surface (X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES)) is used to analyze the depth direction of the plasma polymerized layer, 5% of metal constituent elements in atomic ratio
In the configuration in which the oxygen / carbon (O / C) ratio of the magnetic layer is simply specified, the removal of contaminants and low molecular compounds adhering to the surface of the magnetic layer, that is, the cleaning of the cleaned magnetic layer Since the surface portion is not formed, the adhesion (adhesion) between the magnetic layer and the protective film cannot be sufficiently improved, and the durability and weather resistance cannot be significantly improved.

The present invention solves the above problems,
It is an object of the present invention to provide a method of manufacturing a ferromagnetic metal thin-film magnetic recording medium that can achieve both high electromagnetic conversion characteristics and practical reliability at a high level.

[0021]

In order to achieve the above object, a first aspect of the present invention is to form a ferromagnetic metal thin film on a nonmagnetic substrate, and to form at least an atomic layer on the surface of the ferromagnetic metal thin film in a vacuum. After irradiating a chemically active species (excited species) containing oxygen to provide a dry etching treatment part, a hard carbon film is formed without breaking vacuum, and the surface of the hard carbon film is further formed without breaking vacuum. A method of manufacturing a magnetic recording medium, comprising forming a modified surface by exposing to a glow discharge plasma of a mixed gas of an organic gas and an inorganic gas, and then forming a lubricant layer.

According to a second aspect of the present invention , a ferromagnetic metal thin film is formed on a nonmagnetic substrate, and the surface of the ferromagnetic metal thin film is irradiated with a chemically active species (excited species) containing at least atomic oxygen in a vacuum. After providing a dry etching treatment section, a hard carbon film is formed without breaking vacuum, and the surface of the hard carbon film is formed with nitrogen-containing organic gas, hydrocarbon-based gas and inorganic gas without breaking vacuum. A method for manufacturing a magnetic recording medium, comprising forming a modified surface by exposing the surface to a glow discharge plasma with a mixed gas and then forming a lubricant layer.

According to a third aspect of the present invention, a magnetic metal thin film is formed on a nonmagnetic substrate by a vacuum evaporation method, an ion plating method, or a sputtering method, and at least atomic oxygen is formed on the surface of the ferromagnetic metal thin film without breaking vacuum. After irradiating with a chemically active species (excited species) containing a dry etching treatment unit, a hard carbon film is formed without breaking vacuum, and the surface of the hard carbon film is formed on a nitrogen-containing organic layer without breaking vacuum. A method for manufacturing a magnetic recording medium, comprising forming a modified surface by exposing to a glow discharge plasma of a mixed gas of a system gas and an inorganic gas, and then forming a lubricant layer.

According to a fourth aspect of the present invention, a ferromagnetic metal thin film is formed on a nonmagnetic substrate by a vacuum deposition method, an ion plating method, or a sputtering method, and at least an atomic state is formed on the surface of the ferromagnetic metal thin film without breaking vacuum. After irradiating a chemically active species (excited species) containing oxygen to provide a dry etching treatment part, a hard carbon film is formed without breaking vacuum, and the surface of the hard carbon film is further formed without breaking vacuum. A method for manufacturing a magnetic recording medium, comprising forming a modified surface by exposing to a glow discharge plasma by a mixed gas of an organic gas, a hydrocarbon gas and an inorganic gas, and then forming a lubricant layer. is there.

Further, the surface of the ferromagnetic metal thin film is exposed to an oxidizing gas.
Etching by exposing to glow discharge plasma
A processing unit is provided.

The surface of the hard carbon film is converted to a hydrocarbon gas.
A mixture in which the ratio of nitrogen-containing organic gas to
Reforming by sequential exposure to glow discharge plasma by combined gas
Forming a surface.

The inorganic gases include H ₂ , O ₂ , N
It is preferable to use at least one material selected from H _3.
New

Further, when forming the modified surface, the nitrogen-containing organic system is used.
The gas partial pressure should be between 20% and 70% of the total gas pressure.
Is more preferable.

With the above structure, the surface of the ferromagnetic metal thin film is irradiated with the chemically active species (excited species) containing atomic oxygen without thermally damaging the magnetic recording medium. Since a dry etching portion is formed in which only contaminants and low molecular compounds attached to the ferromagnetic metal thin film are selectively removed, the adhesion between the ferromagnetic metal thin film and the hard carbon film is greatly improved.

Further, a modified material containing an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group introduced into a lubricant molecule.
Since the surface of the hard carbon film is formed on the hard carbon film, the hardness of the protective film including the hard carbon film and the modified surface is not reduced, and the spacing loss between the ferromagnetic metal thin film and the magnetic head is increased. The lubricant molecules can be firmly held on the surface of the magnetic recording medium without causing any problem. In particular the nitrogen concentration in the reformed surface toward the depth direction from the outermost surface (toward the interface between the hard carbon film) in the case of reduction to that structure, moderately relax the internal stress of the reformed surface itself can do.

In order to form a modified surface on the hard carbon film, the surface of the hard carbon film is formed by mixing a nitrogen-containing organic gas and an inorganic gas or a nitrogen-containing organic gas, a hydrocarbon gas and an inorganic gas. By applying a method of exposing to a glow discharge plasma with a gas mixture of the above, it is possible to deposit the chemically active species (reactive species) in the plasma while cleaning the surface of the hard carbon film. Good adhesion to the surface can be ensured.

When the ferromagnetic metal thin film, the dry etching portion and the hard carbon film are continuously formed in a vacuum, or when the ferromagnetic metal thin film, the dry etching portion, the hard carbon film and the modified surface are formed in a vacuum. When formed continuously in a vacuum, the adsorption of moisture and the like from the atmosphere onto the ferromagnetic metal thin film surface and the modified surface can be greatly reduced.

Therefore, the synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exhibited, so that the running stability and the electromagnetic stability are not impaired.
It is possible to provide a magnetic recording medium having dramatically improved durability and weather resistance.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference examples and embodiments of the present invention will be described below in detail with reference to the drawings.

Reference Example 1 FIG. 2 shows Reference Examples 1 and 2 of the present invention, Reference Comparative Examples 1 and 2, and
It is an expanded sectional view showing the composition of the ferromagnetic metal thin film type magnetic tape corresponding to a comparative example except comparative examples 1-3 . In the figure, reference numeral 1 denotes a non-magnetic substrate, which can be made of a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyamide, or polyimide, and has a maximum height roughness (Rmax) of 10 nm on the substrate surface on the magnetic layer side. A microprojection layer 2 having a thickness of about 30 nm is formed. Reference numeral 3 denotes a ferromagnetic metal thin film, which is formed by heating and evaporating a metal or alloy such as Co, Co-Ni or the like with an electron beam or the like in a vacuum atmosphere and continuously introducing a slight amount of oxygen gas into the vacuum chamber. It is formed by an oblique deposition method in which the angle is changed. Its thickness is 150nm
２００200 nm. Reference numeral 4 denotes a back coat layer, which is formed by applying and drying a paint containing carbon black, calcium carbonate, a polyester resin, and a nitrocellulose resin as main components. The thickness is about 500 nm. Numeral 5 denotes a dry etching portion, which is formed by irradiating the surface of the ferromagnetic metal thin film 3 with a chemically active species (excited species) containing atomic oxygen. Its thickness is from 1 nm to 20
nm. Reference numeral 6 denotes a hard carbon film, which can be formed by a plasma CVD method or the like, and has an optimum film thickness of 8 nm to 15 nm in order to ensure reproduction output in a short wavelength region. Reference numeral 8 denotes a fluorine-containing lubricant layer in which a polar group such as a carboxyl group is introduced into a molecule, which is formed by a wet coating method and has a thickness of about 3 nm.

FIG. 3 shows that the dry etching processing part 5 and the hard carbon film 6 constituting the ferromagnetic metal thin film type magnetic tape corresponding to the first embodiment of the present invention are continuously applied in a vacuum. FIG. 1 shows a schematic view of a manufacturing apparatus for forming . In the figure, reference numeral 9 denotes a vacuum chamber, which is evacuated by using a vacuum pump 10 so that the pressure inside the vacuum chamber 9 becomes a high vacuum state of 10 ^-4 torr to 10 ^-5 torr. Reference numeral 11 denotes a raw material for a metal thin film type magnetic tape in which a ferromagnetic metal thin film 3 and a back coat layer 4 are formed on a non-magnetic substrate 1, and is fed from an unwinding roll 12 and has two pass rolls 13, 14.
Then, it is wound around a winding roll 16 via the outer peripheral surface of a cylindrical cooling can 15. The cooling can 15 controls the rotation so that the metal thin film type magnetic tape material 11 can be transported at a constant speed.

Reference numeral 17 denotes a discharge tube (non-equilibrium plasma generation space) for forming the dry etching processing section 5 on the surface of the ferromagnetic metal thin film 3 of the raw material 11 for a metal thin film type magnetic tape. Is provided with a punching metal discharge electrode 18. Punching metal discharge electrode 18
Is connected to a power supply 19 for plasma generation. As the power supply 19 for plasma generation, there are three types: a method of applying only a DC voltage or an AC voltage, and a method of applying a DC voltage and an AC voltage in a superimposed manner. Can be adopted. Reference numeral 20 denotes a source gas inlet for introducing an oxidizing gas into the discharge tube 17.

Reference numeral 21 denotes a discharge tube (non-equilibrium plasma generation space) for forming the hard carbon film 6 on the surface of the dry etching portion 5 of the metal thin film type magnetic tape material 11.
Inside the discharge tube 21, a pipe-shaped discharge electrode 22 is provided. The pipe-shaped discharge electrode 22 is connected to a plasma generation power supply 23. As the plasma generation power supply 23, a method of applying only a DC voltage or an AC voltage or a method of superimposing a DC voltage and an AC voltage is used. Three types of discharge methods of applying a voltage can be adopted. 24
Reference numeral denotes a source gas inlet for introducing a mixed gas (source gas) of a hydrocarbon gas and an inorganic gas such as argon into the discharge tube 21.

Reference Example 1-1 Surface shape analysis by scanning tunneling microscope (STM) showed that the maximum height roughness (Rmax) was 15 nm and the diameter was 200 n.
The small protrusion layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of Co—O is formed on a surface of a 10 μm-thick polyethylene terephthalate film 1 having a thickness of 180 nm using a continuous incident angle changing evaporation method.
Form. Thereafter, a back coat layer 4 having a thickness of 500 nm is formed on the surface on the opposite side of the polyethylene terephthalate film 1 by a wet coating method.

Next, a raw material 11 for a metal thin film type magnetic tape is set inside the vacuum chamber 9 of the manufacturing apparatus shown in FIG.
After evacuating the inside, an oxygen gas (oxidizing gas: O ₂ ) is introduced into the discharge tube 17 and the gas pressure is reduced to 0.05 torr.
The gas flow rate is adjusted so that Hexane gas (hydrocarbon-based gas: C ₆ H ₁₄ ) and argon gas (inorganic-based gas: Ar) were respectively introduced into the discharge tube 21 so that the pressure ratio of hexane gas to argon gas was 4: 1, and the total gas The gas flow rate is adjusted so that the pressure becomes 0.3 torr.
Then, the raw material 11 for a metal thin film type magnetic tape is put at 5 m / mi.
n, and a DC voltage of 800 V is applied to the punching metal discharge electrode 18 to generate a non-equilibrium plasma, which is dried on the surface of the ferromagnetic metal thin film 3 of the raw material 11 for a metal thin film type magnetic tape. The etching portion 5 is formed to a thickness of 5 nm. Further, by applying a DC voltage of 1300 V to the pipe-shaped discharge electrode 22, a non-equilibrium plasma is generated, and the hard carbon film 6 is formed on the surface of the dry etching processing portion 5 of the metal thin film type magnetic tape raw material 11.
Is formed to a thickness of 12 nm.

Next, a fluorine-containing lubricant layer 8 of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the hard carbon film 6 by a wet coating method to a thickness of about 3 nm. And 8 mm wide slits to produce an 8 mm VTR metal thin film magnetic tape.

The Vickers hardness of the hard carbon film 5 obtained in Reference Example 1-1 was 2,600 kg / mm ² .

Reference Example 1-2 Reference Example 1-1 except that the pressure of oxygen gas, which is a raw material gas for forming the dry etching section 5, was 0.1 torr and the thickness of the dry etching section 5 was 8 nm. An 8 mm VTR metal thin-film magnetic tape was produced in the same manner as described above.

Reference Example 1-3 The pressure of oxygen gas as a source gas for forming the dry etching section 5 was set to 0.15 torr, and the DC voltage was set to 150
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Reference Example 1-1 except that the dry etching portion 5 was formed to a thickness of 18 nm by applying 0 V.

Reference Example 1-4 The same as Reference Example 1-1 except that the discharge applied voltage when forming the dry etching processing section 5 was DC voltage of 500 V and the thickness of the dry etching processing section 5 was 2 nm. By the method, a metal thin film type magnetic tape for 8 mm VTR was produced.

REFERENCE EXAMPLE 1-5 An 8 mm VTR was prepared in the same manner as in Reference Example 1-1 except that the thickness of the dry-etched portion 5 was changed to 22 nm.
Metal thin film type magnetic tape was prepared.

Reference Example 1-6 The pressure of oxygen gas, which is a source gas for forming the dry etching section 5, was set to 0.03 torr, and the DC voltage was set to 300.
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Reference Example 1-1 except that the dry etching portion 5 was formed to a thickness of 1 nm by applying V.

Reference Example 1-7 Except that the Vickers hardness of the hard carbon film was set to 1300 kg / mm ² , the same method as in Reference Example 1-1 was applied to 8 m
A metal thin film magnetic tape for mVTR was produced.

[0049] without forming the Reference Comparative Example 1 dry etching unit 5, except that to form the hard carbon film 6 directly on the ferromagnetic metal thin film 3 surface ginseng
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Example 1-1 .

The atomic ratio (O / O / O) of the processing conditions of the dry etching processing unit 5 in the above reference example and reference comparative example .
The chemical bonding state of Co, O / C) and Co atoms is determined according to the raw material 1 for a metal thin film magnetic tape without the fluorinated lubricant layer 8 formed thereon.
1 was analyzed in the depth direction by X-ray photoelectron spectroscopy (XPS) using Ar @ + ion sputtering, and the layer at the time when the atomic ratio of Co atoms to all the constituent elements exceeded 15% was analyzed. . Use the results as reference values
As shown in (Table 1).

[0051]

[Table 1]

The interface of the hard carbon film 6 on the side in contact with the surface of the ferromagnetic metal thin film 3 (the dry etching portion 5) (the layer when the atomic ratio of Co atoms exceeds 5% with respect to all the constituent elements) Also refer to the atomic ratio (O / C) in
The values are shown in (Table 1).

The critical surface tension (γ _C ) value of the surface of the dry etching section 5 in the reference example and the reference comparative example was calculated by the following method. First, a wetting index standard solution having a known surface tension is dropped on the surface of the dry etching processing section 5 using the raw material 11 for a metal thin film magnetic tape on which the hard carbon film 6 is not formed, and the contact angle θ of the droplet is measured. Next, the cosine (cos θ) of the contact angle θ is plotted against the surface tension of the wetting index standard solution (Zismann P
Implementation of lot. ). Line obtained by the least squares method and c
The value of the surface tension corresponding to the intersection with osθ = 1.0 was determined, and the value was defined as the critical surface tension (γ _C ) value of the surface of the dry etching processing section 5. The surface tension of the wetting index standard solution used was 38, 45, 54, 72 × 10 ⁻⁵ N / c.
m. The results are shown in Table 1 as reference values .

A hard carbon film having a thickness of 1 to 3 μm was formed on a silicon wafer in place of the metal thin film type magnetic tape material 11.
Several kinds of samples having a thickness of about m were formed, and the Vickers hardness of the samples was measured using a microhardness tester (microhardness tester).
The Vickers hardness of the hard carbon film corresponding to m was calculated, and the value was used as the Vickers hardness value of the hard carbon film 6 in Reference Example and Reference Comparative Example . The thickness of the hard carbon film in the above sample was a value measured by an ellipsometer. The results are shown in Table 1 as reference values .

Each of the 8 obtained in the above Reference Examples and Comparative Examples
The following measurement was performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) C / N The ratio of the signal (C) at 7 MHz to the noise (N) at 6.5 MHz was measured using an EVS-900 (manufactured by Sony Corporation) as an 8 mm VTR for C / N measurement. It should be noted that C / N of the magnetic tape produced in Reference Example 1-3 was shown as a relative value with reference (0 dB). (2) Still life Using an 8 mm VTR modified for still life measurement,
A video signal was recorded on each magnetic tape under an environment of 3 ° C. and 10% RH, and was reproduced in a still mode under a load of 30 g. The time until the reproduction output dropped by 6 dB was shown. The measurement was terminated for a maximum of 60 minutes. (3) Weather resistance test The weather resistance test was carried out under an environment of 40 ° C. and 90% RH.
The magnetic tape was allowed to stand for 0 days, and the state of occurrence of rust, peeling, and the like was observed with an optical microscope, and evaluated on a 5-point scale. The evaluation was 5 when there was no practical problem and 1 when there was a practical problem.

Table 2 shows the evaluation results of the metal thin film magnetic tapes for 8 mm VTR produced in Reference Example 1 and Reference Comparative Example 1 .

[0057]

[Table 2]

As is clear from (Table 1) and (Table 2),
The metal thin-film magnetic tape of the present embodiment does not thermally damage the metal thin-film magnetic tape by irradiating the surface of the ferromagnetic metal thin film with a chemically active species (excited species) containing atomic oxygen. The adhesion between the ferromagnetic metal thin film and the hard carbon film is dramatically improved by forming a dry etching part where only contaminants and low molecular compounds adhering to the surface of the ferromagnetic metal thin film are selectively removed. To improve. Therefore, the still life and weather resistance can be significantly improved.

In Reference Comparative Example 1 , the dry etching treatment was not formed on the surface of the ferromagnetic metal thin film, and in Reference Example 1-6 , the atomic ratio of oxygen to cobalt and the oxygen to carbon in the dry etching treatment were Is lower , the adhesion between the ferromagnetic metal thin film and the hard carbon film is not improved, and still life,
Weather resistance deteriorated.

In Reference Example 1-5 , since the thickness of the dry-etched portion was too large, the magnetic properties of the ferromagnetic metal thin film deteriorated, resulting in a decrease in C / N.

In Reference Example 1-7 , since the Vickers hardness of the carbon film was low, the still life was deteriorated.

From the above reference example and reference comparative example , the atomic ratio at the interface on the side of the carbon film in contact with the magnetic layer surface (O
/ C) did not significantly affect magnetic tape performance such as still life and weather resistance.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described in detail with reference to the drawings. Note that the present embodiment is different from (Reference Example 1) in that the ferromagnetic metal thin film 3, the dry etching portion 5, and the hard carbon film 6 are continuously formed in a vacuum.

FIG. 4 is a schematic diagram of a manufacturing apparatus for continuously forming a ferromagnetic metal thin film 3, a dry etching processing part 5, and a hard carbon film 6 constituting a ferromagnetic metal thin film type magnetic tape in a vacuum. FIG . In the figure , reference numeral 25 denotes a vacuum chamber, which is evacuated by using a vacuum pump 26 so that the pressure inside the vacuum chamber 25 becomes a high vacuum state of 1 × 10 ⁻⁵ torr. Reference numeral 27 denotes a raw material for a metal thin-film type magnetic tape in which the back coat layer 4 is formed on the non-magnetic substrate 1, and is fed from an unwinding roll 28 and has four pass rolls 29, 30, 31, 32 and a cylindrical shape. Cooling can 3
It is wound on a winding roll 35 via the outer peripheral surfaces of 3 and 34. The cooling cans 33 and 34 serve to control the rotation so that the metal thin film type magnetic tape material 27 can be transported at a constant speed.

Reference numeral 36 denotes a crucible.
An evaporation source 37 made of metal is provided. Reference numeral 38 denotes an electron gun for irradiating the evaporation source 37 with an electron beam to heat and dissolve it, thereby generating a vapor flow. Reference numeral 39 denotes a shielding mask for controlling the angle of incidence of the vapor stream on the metal thin film type magnetic tape material 27 so as to be in the range of 70 ° to 40 °. 4
Numeral 0 denotes an oxygen gas inlet for introducing oxygen gas into the vicinity of the end face of the Co metal deposition section.

Reference numeral 41 denotes a discharge tube (non-equilibrium plasma generation space) for forming the dry etching section 5 on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape raw material 27. Is provided with a punching metal discharge electrode 42. Punching metal discharge electrode 42
Is connected to a plasma generation power supply 43. As the plasma generation power supply 43, there are three types: a method of applying only a DC voltage or an AC voltage, and a method of applying a DC voltage and an AC voltage in a superimposed manner. Can be adopted. Reference numeral 44 denotes a material gas inlet for introducing an oxidizing gas into the discharge tube 41.

Reference numeral 45 denotes a discharge tube (non-equilibrium plasma generation space) for forming the hard carbon film 6 on the surface of the dry etching portion 5 of the metal thin film type magnetic tape material 27.
Inside the discharge tube 45, a pipe-shaped discharge electrode 46 is provided. The pipe-shaped discharge electrode 46 is connected to a plasma generation power supply 47. As the plasma generation power supply 47, a method in which only a DC voltage or an AC voltage is applied, or a method in which a DC voltage and an AC voltage are superimposed. Three types of discharge methods of applying a voltage can be adopted. 48
Is a source gas inlet for introducing a mixed gas (source gas) of a hydrocarbon gas and an inorganic gas such as argon into the discharge tube 45.

Reference Example 2-1 Surface shape analysis by scanning tunneling microscope (STM) showed that the maximum height roughness (Rmax) was 15 nm and the diameter was 200 n.
The small protrusion layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A backcoat layer 4 having a thickness of 500 nm is formed on the surface on the opposite side of the provided 10 μm-thick polyethylene terephthalate film 1 by a wet coating method.

Next, the raw material 27 for metal thin film magnetic tape is set inside the vacuum chamber 25 of the manufacturing apparatus shown in FIG. 4, and the inside of the vacuum chamber 25 is evacuated. Is transported at a traveling speed of 20 m / min, and a small amount of oxygen is introduced from the oxygen gas inlet 40 into the vacuum chamber 25, and electrons emitted from the electron gun 38 to the evaporation source 37 made of Co metal in the crucible 36. A beam is irradiated to heat and evaporate the evaporation source 37, and the incident angle is 70 ° to 4 °.
In the range of 0 °, a ferromagnetic metal thin film 3 (Co—O vapor-deposited film) having a thickness of 180 nm is formed on the surface of the polyethylene terephthalate film 1 on which the microprojection layer 2 is formed.

Further, an oxygen gas (oxidizing gas: O ² ) is introduced into the discharge tube 41, and a DC voltage of 1200 V is applied to the punching metal discharge electrode 18 in a state where the gas pressure is set to 0.2 torr, and a non-equilibrium plasma is applied. Is formed, and a dry etching portion 5 is formed to a thickness of 5 nm on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape material 27.

Further, toluene gas (hydrocarbon-based gas: C ₇ H ₈ ) and argon gas (inorganic-based gas: A
r) were introduced, and a DC voltage of 150 was applied to the pipe-shaped discharge electrode 46 with the pressure ratio of toluene gas to argon gas set to 4: 1, and the total gas pressure set to 0.3 torr.
A non-equilibrium plasma is generated by applying 0 V, and a hard carbon film 6 having a thickness of 10 nm is formed on the surface of the dry etching portion 5 of the raw material 27 for a metal thin film magnetic tape.

Next, a fluorine-containing lubricant layer 8 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the hard carbon film 6 by a wet coating method to a thickness of about 3 nm. And 8 mm wide slits to produce an 8 mm VTR metal thin film magnetic tape.

The Vickers hardness of the hard carbon film 5 obtained in Reference Example 2-1 was 2700 kg / mm ² .

Reference Example 2-2 The pressure of oxygen gas, which is a source gas for forming the dry etching section 5, was set to 0.15 torr, and the DC voltage was set to 900.
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Reference Example 2-1 except that the dry etching portion 5 was formed to a thickness of 3 nm by applying V.

REFERENCE EXAMPLE 2-3 After forming a ferromagnetic metal thin film 3 in the same manner as in Reference Example 2-1 , the vacuum was once broken and the raw material for a metal thin film type magnetic tape 2 was released.
7 in a 23 ° C.-60% RH environment for 3 days,
Ginseng except that continuous forming dry etching process unit 5, a hard carbon film 6 in vacuum in the same manner as in Reference Example 2-1 METHOD
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Example 2-1 .

COMPARATIVE REFERENCE EXAMPLE 2 A ferromagnetic metal thin film 3 and a hard carbon film 6 were formed on a surface of a polyethylene terephthalate film 1 on which a microprojection layer 2 was formed in a vacuum without forming a dry etching portion 5.
Was formed in the same manner as in Reference Example 2-1 except that the film was continuously formed.

[0077] and process conditions for the dry etching unit 5 in the Reference Examples and Reference Comparative Example, the atomic ratio (O / Co, O
/ C) and the chemical bond state of Co atoms, the critical surface tension (γ _C ) of the surface of the dry etching treatment section 5 and the Vickers hardness of the hard carbon film 6 were measured by the same method as in (Reference Example 1) . . Using the results as reference values (Table 3)
Shown in

[0078]

[Table 3]

Each of the 8 samples obtained in the above Examples and Comparative Examples
The following measurement was performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) C / N The ratio of the signal (C) at 7 MHz to the noise (N) at 6.5 MHz was measured using an EVS-900 (manufactured by Sony Corporation) as an 8 mm VTR for C / N measurement. The C / C of the magnetic tape produced in Reference Comparative Example 2-1
N is indicated as a relative value with reference (0 dB). (2) Still life Using an 8 mm VTR modified for still life measurement,
A video signal was recorded on each magnetic tape under an environment of 3 ° C. and 10% RH, and was reproduced in a still mode under a load of 30 g. The time until the reproduction output dropped by 6 dB was shown. The measurement was terminated for a maximum of 60 minutes. (3) Weather resistance test The weather resistance test was carried out under an environment of 40 ° C. and 90% RH.
The magnetic tape was allowed to stand for 0 days, and the state of occurrence of rust, peeling, and the like was observed with an optical microscope, and evaluated on a 5-point scale. The evaluation was 5 when there was no practical problem and 1 when there was a practical problem. (4) Reduction rate of Bsδ The Bsδ value of each magnetic tape was measured before and after the weathering test, and the BSδ was measured.
Was determined.

Table 4 shows the evaluation results of the metal thin film magnetic tapes for 8 mm VTR produced in each of the Reference Examples and Reference Comparative Examples .

[0081]

[Table 4]

As apparent from (Table 3) and (Table 4),
The metal thin-film magnetic tape of this reference example does not thermally damage the metal thin-film magnetic tape by irradiating the surface of the ferromagnetic metal thin film with a chemically active species (excited species) containing atomic oxygen. The adhesion between the ferromagnetic metal thin film and the hard carbon film is dramatically improved by forming a dry etching part where only contaminants and low molecular compounds adhering to the surface of the ferromagnetic metal thin film are selectively removed. To improve. Therefore, the still life and weather resistance can be significantly improved. Furthermore, by continuously forming the ferromagnetic metal thin film, the dry etching portion, and the hard carbon film in a vacuum, the adsorption of moisture and the like from the air to the surface of the ferromagnetic metal thin film can be significantly reduced. Therefore, it is possible to reduce the rate of decrease of Bsδ.

In Reference Example 2-3, the rate of decrease in Bsδ was increased due to the adsorption of moisture and the like from the air onto the surface of the ferromagnetic metal thin film.

In Comparative Reference Example 2 , since no dry-etched portion was formed on the surface of the ferromagnetic metal thin film, the adhesion between the ferromagnetic metal thin film and the hard carbon film was not sufficiently improved, and the still life and weather resistance were not improved. And the rate of decrease of Bsδ deteriorated.

(Embodiment 1) The first embodiment of the present invention corresponds to claims 1, 5, 7, 8, and 9 of the present invention.
Embodiment 1 will be described in detail with reference to the drawings.

FIG. 1 is an enlarged sectional view showing the structure of a ferromagnetic metal thin film type magnetic tape corresponding to each embodiment . In the figure, 1
Is a non-magnetic substrate, and a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyamide, or polyimide can be used. The substrate surface on the side of the magnetic layer has a maximum height roughness (Rmax) of 10 nm to 30 nm. The projection layer 2 is formed. Reference numeral 3 denotes a ferromagnetic metal thin film, which is formed by heating and evaporating a metal or alloy such as Co, Co-Ni or the like with an electron beam or the like in a vacuum atmosphere and continuously introducing a slight amount of oxygen gas into the vacuum chamber. It is formed by an oblique deposition method in which the angle is changed. Its film thickness is 150n
m to 200 nm. 4 is a back coat layer, which includes carbon black, calcium carbonate, polyester resin,
It is formed by applying and drying a paint containing nitrocellulose resin as a main component. The thickness is about 500 nm. Numeral 5 denotes a dry etching part, which is a chemically active species (excited species) containing atomic oxygen on the surface of the ferromagnetic metal thin film 3.
Is formed by irradiation. Its thickness is 1nm ~ 2
0 nm. Reference numeral 6 denotes a hard carbon film, which is formed by plasma CVD.
The film thickness is optimally 8 nm to 15 nm in order to ensure reproduction output in a short wavelength region. Reference numeral 7 denotes a modified surface, which is formed by exposing the surface of the hard carbon film 6 to glow discharge plasma using a mixed gas of a nitrogen-containing organic gas and an inorganic gas. Its thickness is less than 3 nm. Reference numeral 8 denotes a fluorine-containing lubricant layer in which a polar group such as a carboxyl group is introduced into a molecule, which is formed by a wet coating method and has a thickness of about 3 nm.

FIG. 5 shows that the dry etching portion 5, the hard carbon film 6, and the modified surface 7 constituting the ferromagnetic metal thin film type magnetic tape of the second invention are continuously formed in a vacuum. FIG. 1 is a schematic view of a manufacturing apparatus for the present invention.
(In other words, it corresponds to the method of manufacturing the ferromagnetic metal thin film type magnetic tape according to the sixth aspect of the present invention.) In the figure, reference numeral 9 denotes a vacuum chamber, and the pressure inside the vacuum chamber 9 is 10 ^{−4 ton} using a vacuum pump 10.
Evacuation is performed so as to be in a high vacuum state of rr to 10 ^-5 torr. Reference numeral 11 denotes a ferromagnetic metal thin film 3 on a non-magnetic substrate 1.
And a raw material for a metal thin film type magnetic tape on which a back coat layer 4 is formed, which is sent out from an unwinding roll 12,
Two pass rolls 13 and 14 and a cylindrical cooling can 1
5 is wound around a winding roll 16 via the outer peripheral surface. The cooling can 15 controls the rotation so that the metal thin film type magnetic tape material 11 can be transported at a constant speed.

Reference numeral 17 denotes a discharge tube (non-equilibrium plasma generation space) for forming the dry etching processing section 5 on the surface of the ferromagnetic metal thin film 3 of the raw material 11 for a metal thin film magnetic tape. Is provided with a punching metal discharge electrode 18. Punching metal discharge electrode 18
Is connected to a power supply 19 for plasma generation. As the power supply 19 for plasma generation, there are three types: a method of applying only a DC voltage or an AC voltage, and a method of applying a DC voltage and an AC voltage in a superimposed manner. Can be adopted. Reference numeral 20 denotes a source gas inlet for introducing an oxidizing gas into the discharge tube 17.

Reference numeral 21 denotes a discharge tube (non-equilibrium plasma generation space) for forming the hard carbon film 6 on the surface of the dry etching portion 5 of the metal thin film type magnetic tape material 11.
Inside the discharge tube 21, a pipe-shaped discharge electrode 22 is provided. The pipe-shaped discharge electrode 22 is connected to a plasma generation power supply 23. As the plasma generation power supply 23, a method of applying only a DC voltage or an AC voltage or a method of superimposing a DC voltage and an AC voltage is used. Three types of discharge methods of applying a voltage can be adopted. 24
Reference numeral denotes a source gas inlet for introducing a mixed gas (source gas) of a hydrocarbon gas and an inorganic gas such as argon into the discharge tube 21.

Reference numeral 49 denotes a discharge tube (non-equilibrium plasma generation space) for forming the modified surface 7 on the hard carbon film 6, and a punching metal discharge electrode 50 is provided inside the discharge tube 49. . The punching metal discharge electrode 50 is connected to a power supply 51 for plasma generation. The power supply 51 for plasma generation is a method of applying only a DC voltage or an AC voltage, or a method of superimposing a DC voltage and an AC voltage. Three types of discharge methods of applying a voltage can be adopted. Reference numeral 52 denotes a raw material gas inlet for introducing a mixed gas (raw gas) of a nitrogen-containing organic gas and an inorganic gas into the discharge tube 49.

Example 1-1 Surface shape analysis by scanning tunneling microscope (STM) showed that the maximum height roughness (Rmax) was 15 nm and the diameter was 200 n.
The small protrusion layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of Co—O is formed on a surface of a 10 μm-thick polyethylene terephthalate film 1 having a thickness of 180 nm using a continuous incident angle changing evaporation method.
Form. Thereafter, a back coat layer 4 having a thickness of 500 nm is formed on the surface on the opposite side of the polyethylene terephthalate film 1 by a wet coating method.

Next, the raw material 11 for a metal thin film type magnetic tape is set inside the vacuum chamber 9 of the manufacturing apparatus shown in FIG.
After evacuating the inside, an oxygen gas (oxidizing gas: O ₂ ) is introduced into the discharge tube 17 and the gas pressure is reduced to 0.05 torr.
The gas flow rate is adjusted so that Hexane gas (hydrocarbon-based gas: C ₆ H ₁₄ ) and argon gas (inorganic-based gas: Ar) were respectively introduced into the discharge tube 21 so that the pressure ratio of hexane gas to argon gas was 4: 1, and the total gas The gas flow rate is adjusted so that the pressure becomes 0.3 torr.
Further, pyridine gas (nitrogen-containing organic gas: C ₅ H ₅ N) and hydrogen gas (inorganic gas: H ₂ ) are respectively introduced into the discharge tube 49, and the pressure ratio of pyridine gas to hydrogen gas is 3:
2. Adjust the gas flow rate so that the total gas pressure becomes 0.1 torr. Then, the raw material for metal thin film magnetic tape 1
1 at a traveling speed of 5 m / min while applying a DC voltage of 800 to the punching metal discharge electrode 18.
By applying V, a non-equilibrium plasma is generated, and a dry etching portion 5 is formed to a thickness of 5 nm on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape raw material 11. In addition, a non-equilibrium plasma is generated by applying a DC voltage of 1300 V to the pipe-like discharge electrode 22, and a hard carbon film 6 having a thickness of 12 nm is formed on the surface of the dry etching processing section 5 of the raw material 11 for a metal thin film type magnetic tape. Form. Further, by applying a DC voltage of 1500 V to the punching metal discharge electrode 50, a non-equilibrium plasma is generated, and a modified surface 7 having a thickness of 1 nm is formed on the surface of the hard carbon film 6 of the raw material 11 for a metal thin film type magnetic tape. .

Next, a fluorine-containing lubricant layer 8 of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the modified surface 7 by a wet coating method to a thickness of about 3 nm. And 8 mm wide slits to produce an 8 mm VTR metal thin film magnetic tape.

The Vickers hardness of the hard carbon film 6 obtained in Example 1-1 was 2,600 kg / mm ² .

Example 1-2 The pressure of oxygen gas, which is a raw material gas for forming the dry etching section 5, was set to 0.1 torr, the thickness of the dry etching section 5 was set to 8 nm, and the modified surface 7 was formed. Example 1 except that allylamine (nitrogen-containing organic gas: C3H7N) was used as a raw material gas instead of pyridine, and the pressure ratio between allylamine gas and hydrogen gas was 1: 1.
In the same manner as in -1 , an 8 mm VTR metal thin film magnetic tape was produced.

Example 1-3 The pressure of oxygen gas, which is a source gas for forming the dry etching section 5, was set to 0.2 torr, and the DC voltage was set to 1000
An 8 mm VTR metal thin-film magnetic tape was manufactured in the same manner as in Example 1-1 , except that the dry etching portion 5 was formed to a thickness of 19 nm by applying V.

Example 1-4 The same procedure as in Example 1-1 was performed except that the discharge applied voltage when forming the dry etching processing portion 5 was DC voltage 500 V and the thickness of the dry etching processing portion 5 was 2 nm. By the method, a metal thin film type magnetic tape for 8 mm VTR was produced.

Example 1-5 As a raw material gas for forming the modified surface 7, allylamine was used instead of pyridine, and ammonia (inorganic gas: NH ₃ ) was used instead of hydrogen. Example 1 except that the pressure ratio was 1: 3
In the same manner as in Example 1 , an 8 mm VTR metal thin film magnetic tape was produced.

Example 1-6 The pressure ratio between pyridine gas and hydrogen gas, which are source gases for forming the reformed surface 7, was 1: 2, the total gas pressure was 0.3 torr, and the thickness of the reformed surface 7 was 2 mm. except that .5nm formed embodiment
In the same manner as in Example 1-1 , a metal thin film magnetic tape for 8 mm VTR was produced.

Reference Example 11-1 An 8 mm VTR was produced in the same manner as in Example 1-1 , except that the thickness of the dry etching processing portion 5 was set to 24 nm.
Metal thin film type magnetic tape was prepared.

Reference Example 11-2 The pressure of oxygen gas, which is a source gas for forming the dry etching section 5, was set to 0.03 torr, and the DC voltage was set to 300.
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Example 1-1 except that the dry etching portion 5 was formed to a thickness of 1 nm by applying V.

Reference Example 11-3 A mixed gas of pyridine, benzene and hydrogen was used as a raw material gas for forming the modified surface 7 instead of a mixed gas of pyridine and hydrogen, and the pressure ratio was 1: 5: 1. the embodiment except that
In the same manner as in Example 1-1 , a metal thin film magnetic tape for 8 mm VTR was produced.

Reference Example 11-4 Example 1-1 except that the thickness of the modified surface 7 was 4 nm.
An 8 mm VTR metal thin-film magnetic tape was produced in the same manner as described above.

Reference Example 11-5 Except that the Vickers hardness of the hard carbon film was set to 1300 kg / mm ² , the same method as in Example 1-1 was applied to 8 m
A metal thin film magnetic tape for mVTR was produced.

Comparative Example 1-1 The hard carbon film 6 was formed directly on the surface of the ferromagnetic metal thin film 3 without forming the dry etching portion 5, and the hard carbon film 6 was formed directly without forming the modified surface 7. An 8 mm VTR metal thin film magnetic tape was produced in the same manner as in Example 1-1 , except that the fluorine-containing lubricant layer 8 was formed on the surface of the film 6.

[0106] without forming the Comparative Examples 1-2 the dry etching processing section 5, except that to form the hard carbon film 6 directly on the ferromagnetic metal thin film 3 surface-
In the same manner as in Example 1-1 , a metal thin film magnetic tape for 8 mm VTR was produced.

Comparative Example 1-3 A method similar to that of Example 1-1 was used except that benzene (hydrocarbon-based gas: C ₆ H ₆ ) was used instead of pyridine as a raw material gas for forming the modified surface 7. , 8 mm VTR metal thin film type magnetic tape.

In the examples and comparative examples, the atomic ratio (O / Co, O / C) and the chemical bonding state of Co atoms in the dry etching section 5, the critical surface tension (γ _C ) of the surface of the dry etching section 5, and The Vickers hardness of the hard carbon film 6 was measured by the same method as in (Reference Example 1) . The results are shown in Table 5 as reference values .

[0109]

[Table 5]

The processing conditions, the chemical composition (atomic ratio) and the chemical bonding state of the modified surface 7 in Examples, Reference Examples and Comparative Examples are as follows for the metal thin film type magnetic tape without the fluorinated lubricant layer 8 formed. X-ray photoelectron spectroscopy (X
(PS) surface analysis, and refer to the results
The values are shown in (Table 5).

Each of the 8 samples obtained in the above Examples and Comparative Examples
The following measurement was performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) C / N The ratio of the signal (C) at 7 MHz to the noise (N) at 6.5 MHz was measured using an EVS-900 (manufactured by Sony Corporation) as an 8 mm VTR for C / N measurement. It should be noted that the relative values are shown with the C / N of the magnetic tape produced in Example 1-3 as a reference (0 dB). (2) Still life Using an 8 mm VTR modified for still life measurement,
A video signal was recorded on each magnetic tape under an environment of 3 ° C. and 10% RH, and was reproduced in a still mode under a load of 30 g. The time until the reproduced output dropped by 6 dB was shown. The measurement was terminated for a maximum of 60 minutes. (3) Weather resistance test The weather resistance test was carried out under an environment of 40 ° C. and 90% RH.
The magnetic tape was allowed to stand for 0 days, and the state of occurrence of rust, peeling, and the like was observed with an optical microscope, and evaluated on a 5-point scale. The evaluation was 5 when there was no practical problem and 1 when there was a practical problem. (4) Still life after storage in a high-temperature, high-humidity environment Using an 8 mm VTR modified for still life measurement,
A video signal was recorded on each magnetic tape after the weather resistance test in an environment of 3 ° C. and 10% RH, and reproduced in a still mode under a load of 30 g, and the time until the reproduced output dropped by 6 dB was shown. . The measurement was terminated for a maximum of 60 minutes. (5) Stainless steel with a friction coefficient μk of 4 mm in diameter and a surface roughness of 0.2 S (SUS4
20J2) The magnetic layer forming surface of each magnetic tape after the weather resistance test is brought into contact with the cylinder over 90 °, the input side tension is set to 30 g, and the tape traveling speed is set to 0.5 mm / sec with respect to the stainless steel cylinder. The output side tension Xg at the set time was measured, and the friction coefficient was determined from the following equation.

[0112]

(Equation 1)

The measurement environment was 25 ° C.-30% RH, and the measured value in the 30th pass was adopted as the friction coefficient.

Table 6 shows the evaluation results of the metal thin film magnetic tapes for 8 mm VTR produced in each of the examples, reference examples, and comparative examples.

[0115]

[Table 6]

As apparent from (Table 5) and (Table 6),
The metal thin-film magnetic tape of the present embodiment does not thermally damage the metal thin-film magnetic tape by irradiating the surface of the ferromagnetic metal thin film with a chemically active species (excited species) containing atomic oxygen. The adhesion between the ferromagnetic metal thin film and the hard carbon film is dramatically improved by forming a dry etching part where only contaminants and low molecular compounds adhering to the surface of the ferromagnetic metal thin film are selectively removed. To improve. Furthermore, a thickness containing an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group (carboxyl group) introduced into the lubricant molecule.
Since the modified surface of less than nm is formed on the hard carbon film, the hardness of the protective film composed of the hard carbon film and the modified surface is not reduced and the spacing between the ferromagnetic metal thin film and the magnetic head is reduced. The lubricant molecules can be firmly held on the tape surface without increasing the loss. In addition, in order to form a modified surface on the hard carbon film, the surface of the hard carbon film is exposed to glow discharge plasma by a mixed gas of a nitrogen-containing organic gas and an inorganic gas to apply a method of forming the modified surface on the hard carbon film. Since the chemically active species (reactive species) in the plasma can be deposited while cleaning, good adhesion between the hard carbon film and the modified surface can be ensured. Therefore, since the synergistic effect between the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exhibited, the durability,
It has become possible to dramatically improve weather resistance and running stability.

In Reference Example 11-1 , since the thickness of the dry-etched portion was too large, the magnetic properties of the ferromagnetic metal thin film deteriorated, and the C / N ratio tended to decrease.

In Reference Example 11-2, the dry etching
To the atomic ratio of oxygen to cobalt and carbon
If the atomic ratio of oxygen to oxygen is below the appropriate range
It seems that the adhesion between the ferromagnetic metal thin film and the hard carbon film
Still after storage in high temperature and high humidity environment
Life tended to decrease.

In Reference Example 11-3, carbon on the reformed surface
Atomic ratio of nitrogen to oxygen and atomic ratio of nitrogen to oxygen
Is considered to be below the appropriate range, the hard carbon film and
The degree of improvement in adhesion to fluorine-based lubricants is small.
If, still life and coefficient of friction μk after storage at high temperature and high humidity
It became worse.

In Reference Example 11-4 , the modified surface was formed as an intermediate layer by the chemical affinity between the nitrogen atom contained in the modified surface and the polar group (carboxyl group) introduced into the lubricant molecule. Although the carbon film and the lubricant layer are firmly adhered to each other, the synergistic effect of the wear resistance of the hard carbon film and the low shear force of the lubricant layer is sufficiently exhibited because the thickness of the modified surface is too large. However, the degree of improvement in still life and still life after storage in a high-temperature, high-humidity environment tended to be small .

In Reference Example 11-5 , since the Vickers hardness of the carbon film was low, the still life, the still life after storage in a high-temperature, high-humidity environment, and the like tended to deteriorate.

In Comparative Example 1-1 , since neither the dry-etched portion nor the modified surface was formed, the adhesion between the ferromagnetic metal thin film and the hard carbon film and the hard carbon film and the fluorine-containing lubricant layer The adhesion was not improved, and still life, still life after storage in a high temperature and high humidity environment, weather resistance, and friction coefficient μk after storage in a high temperature and high humidity environment were significantly deteriorated.

In Comparative Example 1-2 , since no dry-etched portion was formed on the surface of the ferromagnetic metal thin film, the adhesion between the ferromagnetic metal thin film and the hard carbon film was not improved, and storage in a high-temperature, high-humidity environment was performed. Later still life deteriorated.

In Comparative Example 1-3 , the raw material gas for forming the modified surface on the hard carbon film does not contain the specific element (nitrogen atom) of the present invention in the molecule. The adhesiveness between the film and the fluorine-containing lubricant layer was not improved, resulting in deterioration of the still life, the still life after storage in a high temperature and high humidity environment, and the friction coefficient μk after storage in a high temperature and high humidity environment.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to claims 2, 5, 6, 7, 8, and 9.
A corresponding embodiment 2 will be described in detail with reference to the drawings. The difference between this embodiment and (embodiment 1) is that the nitrogen concentration of the modified surface 7 decreases from the outermost surface in the depth direction (toward the interface with the hard carbon film 6). Is to be.

FIG. 6 shows that the dry etching processing part 5, the hard carbon film 6, and the modified surface 7 having the concentration gradient of nitrogen atoms constituting the ferromagnetic metal thin film type magnetic tape of the second invention are evacuated. FIG. 2 shows a schematic view of a manufacturing apparatus for continuously forming the inside . In the figure , reference numeral 9 denotes a vacuum chamber, and the pressure inside the vacuum chamber 9 is increased to 10 ^{-4 ton} using a vacuum pump 10.
Evacuation is performed so as to be in a high vacuum state of rr to 10 ^-5 torr. Reference numeral 11 denotes a ferromagnetic metal thin film 3 on a non-magnetic substrate 1.
And a raw material for a metal thin film type magnetic tape on which a back coat layer 4 is formed, which is sent out from an unwinding roll 12,
Two pass rolls 13 and 14 and a cylindrical cooling can 1
5 is wound around a winding roll 16 via the outer peripheral surface. The cooling can 15 controls the rotation so that the metal thin film type magnetic tape material 11 can be transported at a constant speed.

Reference numeral 17 denotes a discharge tube (non-equilibrium plasma generation space) for forming the dry etching section 5 on the surface of the ferromagnetic metal thin film 3 of the raw material 11 for a metal thin film magnetic tape. Is provided with a punching metal discharge electrode 18. Punching metal discharge electrode 18
Is connected to a power supply 19 for plasma generation. As the power supply 19 for plasma generation, there are three types: a method of applying only a DC voltage or an AC voltage, and a method of applying a DC voltage and an AC voltage in a superimposed manner. Can be adopted. Reference numeral 20 denotes a source gas inlet for introducing an oxidizing gas into the discharge tube 17.

Reference numeral 21 denotes a discharge tube (non-equilibrium plasma generation space) for forming the hard carbon film 6 on the surface of the dry etching portion 5 of the raw material 11 for a metal thin film magnetic tape.
Inside the discharge tube 21, a pipe-shaped discharge electrode 22 is provided. The pipe-shaped discharge electrode 22 is connected to a plasma generation power supply 23. As the plasma generation power supply 23, a method of applying only a DC voltage or an AC voltage or a method of superimposing a DC voltage and an AC voltage is used. Three types of discharge methods of applying a voltage can be adopted. 24
Reference numeral denotes a source gas inlet for introducing a mixed gas (source gas) of a hydrocarbon gas and an inorganic gas such as argon into the discharge tube 21.

Reference numerals 53, 54, and 55 denote discharge tubes (non-equilibrium plasma generation spaces) for forming the modified surface 7 on the hard carbon film 6. Punching metal is provided inside the discharge tubes 53, 54, and 55. Discharge electrodes 56, 57, 58 are provided respectively. Punching metal discharge electrodes 56, 57, 5
Numeral 8 is connected to plasma generation power supplies 59, 60, 61, respectively. As the plasma generation power supplies 59, 60, 61, a method of applying only a DC voltage or an AC voltage, a DC voltage and an AC voltage, , And three types of discharge methods, i. 6
2, 63 and 64 are nitrogen-containing organic gases, hydrocarbon gases,
A mixed gas (raw material gas) composed of an inorganic gas is supplied to the discharge tube 5
These are raw material gas inlets for introducing into 3, 54 and 55, respectively.

Example 2-1 Surface shape analysis by scanning tunneling microscope (STM) showed that the maximum height roughness (Rmax) was 15 nm and the diameter was 200 n.
The small protrusion layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of Co—O is formed on a surface of a 10 μm-thick polyethylene terephthalate film 1 having a thickness of 180 nm using a continuous incident angle changing evaporation method.
Form. Thereafter, a back coat layer 4 having a thickness of 500 nm is formed on the surface on the opposite side of the polyethylene terephthalate film 1 by a wet coating method.

Next, the raw material 11 for a metal thin film type magnetic tape is set inside the vacuum chamber 9 of the manufacturing apparatus shown in FIG.
After evacuating the inside, an oxygen gas (oxidizing gas: O ₂ ) is introduced into the discharge tube 17 and the gas pressure is reduced to 0.05 torr.
The gas flow rate is adjusted so that Hexane gas (hydrocarbon-based gas: C ₆ H ₁₄ ) and argon gas (inorganic-based gas: Ar) were respectively introduced into the discharge tube 21 so that the pressure ratio of hexane gas to argon gas was 4: 1, and the total gas The gas flow rate is adjusted so that the pressure becomes 0.3 torr.
Further, n-propylamine gas (nitrogen-containing organic gas: C ₃ H ₉ N), methane gas (hydrocarbon gas: CH ₄ ), and hydrogen gas (inorganic gas: H ₂ ) are introduced into the discharge tube 53. The pressure ratio of n-propylamine gas, methane gas and hydrogen gas is 2: 7: 1, and the total gas pressure is 0.1 ton.
The gas flow rate is adjusted to be rr. Next, discharge tube 5
4, n-propylamine gas, methane gas and hydrogen gas are respectively introduced, the pressure ratio of n-propylamine gas, methane gas and hydrogen gas is 4.5: 4.5: 1, and the total gas pressure is 0.1 torr. The gas flow rate is adjusted so that Further, n-propylamine gas, methane gas, and hydrogen gas are respectively introduced into the discharge tube 55, and the pressure ratio of n-propylamine gas, methane gas, and hydrogen gas is 7: 2:
1. Adjust the gas flow rate so that the total gas pressure becomes 0.1 torr. Then, the raw material for metal thin film magnetic tape 1
1 at a traveling speed of 5 m / min while applying a DC voltage of 800 to the punching metal discharge electrode 18.
By applying V, a non-equilibrium plasma is generated, and a dry etching portion 5 is formed to a thickness of 5 nm on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape raw material 11. In addition, a non-equilibrium plasma is generated by applying a DC voltage of 1300 V to the pipe-like discharge electrode 22, and a hard carbon film 6 having a thickness of 12 nm is formed on the surface of the dry etching processing section 5 of the raw material 11 for a metal thin film type magnetic tape. Form. Further, a DC voltage of 200 is applied to the punching metal discharge electrodes 56, 57, 58.
By applying 0 V, non-equilibrium plasma is generated, and the nitrogen concentration on the surface of the hard carbon film 6 of the metal thin film-type magnetic tape raw material 11 increases in the depth direction from the outermost surface (the hard carbon film 6).
A modified surface 7 having a reduced thickness of 2 nm (in the direction of the interface with the interface) is formed.

Next, a fluorine-containing lubricant layer 8 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the modified surface 7 by a wet coating method to a thickness of about 3 nm. And 8 mm wide slits to produce an 8 mm VTR metal thin film magnetic tape.

The Vickers hardness of the hard carbon film 6 obtained in Example 2-1 was 2600 kg / mm ² .

Example 2-2 The pressure of oxygen gas, which is a source gas for forming the dry etching portion 5, was set to 0.1 torr, the thickness of the dry etching portion 5 was set to 8 nm, and the thickness of the dry etching portion 5 was changed. In the same manner as in Example 2-1 except that allylamine (nitrogen-containing organic gas: C ₃ H ₇ N) was used instead of n-propylamine as the raw material gas for the metal thin film magnetic tape for 8 mm VTR, Produced.

Embodiment 2-3 The pressure of the oxygen gas as the source gas for forming the dry etching section 5 was set to 0.2 torr, and the DC voltage was set to 1000
An 8 mm VTR metal thin-film magnetic tape was manufactured in the same manner as in Example 2-1 except that the dry etching portion 5 was formed to a thickness of 19 nm by applying V.

Example 2-4 The same procedure as in Example 2-1 was carried out except that the applied voltage for forming the dry etching processing section 5 was DC voltage of 500 V, and the thickness of the dry etching processing section 5 was 2 nm. By the method, a metal thin film type magnetic tape for 8 mm VTR was produced.

Example 2-5 Example 2-1 except that a 2.5-nm-thick modified surface 7 in which the nitrogen concentration decreased from the outermost surface in the depth direction was formed on the surface of the hard carbon film 6. 8mmV by the same method as
A metal thin film magnetic tape for TR was produced.

Example 2-6 The total gas pressure of the source gas for forming the reformed surface 7 was 0.05 to
and rr, real except that thickness of 1nm form a modified surface 7
In the same manner as in Example 2-1 , an 8 mm VTR metal thin film magnetic tape was produced.

Example 2-7 As a source gas for forming the modified surface 7, pyridine (nitrogen-containing organic gas: C ₅ H ₅ N) was used instead of n-propylamine, and the total gas pressure was 0.05 torr. An 8 mm VTR metal thin film magnetic tape was produced in the same manner as in Example 2-1 except that the modified surface 7 was formed to a thickness of 1 nm.

Reference Example 21-1 An 8 mm VTR was prepared in the same manner as in Example 2-1 except that the thickness of the dry-etched portion 5 was set to 24 nm.
Metal thin film type magnetic tape was prepared.

Reference Example 21-2 The pressure of the oxygen gas, which is the source gas for forming the dry etching portion 5, was set to 0.03 torr, and the DC voltage was set to 300.
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Example 2-1 except that the dry etching portion 5 was formed to a thickness of 1 nm by applying V.

Reference Example 21-3 As a raw material gas for forming the modified surface 7, n-propylamine, methane and oxygen (inorganic gas: O ₂ ) instead of a mixed gas of n-propylamine, methane and hydrogen And a pressure ratio of 2: 7: 1, 4.5: 4.5: 1,
An 8 mm VTR metal thin film magnetic tape was produced in the same manner as in Example 2-1 except that the ratio was 1: 7: 2.

Reference Example 21-4 Same as Example 2-1 except that a 4 nm-thick modified surface 7 in which the nitrogen concentration decreased from the outermost surface in the depth direction was formed on the surface of the hard carbon film 6. 8mm VTR
Metal thin film type magnetic tape was prepared.

Reference Example 21-5 The same procedure as in Example 2-1 was carried out except that the Vickers hardness of the hard carbon film was set to 1300 kg / mm ^2, and 8 m
A metal thin film magnetic tape for mVTR was produced.

COMPARATIVE EXAMPLE 2 Except that the hard carbon film 6 was formed directly on the surface of the ferromagnetic metal thin film 3 without forming the dry etching processing part 5, the actual
In the same manner as in Example 2-1 , an 8 mm VTR metal thin film magnetic tape was produced.

[0146] Dry etching process section 5 in Example
And the atomic ratios of the comparative examples (O / Co, O /
C) The chemical bonding state of Co atoms and Co atoms, the critical surface tension (γ _C ) of the surface of the dry etching section 5, and the Vickers hardness of the hard carbon film 6 were measured by the same method as in (Reference Example 1) . The results are shown in Table 7 as reference values .

[0147]

[Table 7]

The modified surface 7 formed on the surface of the hard carbon film 6 in Examples, Reference Examples and Comparative Examples has a structure in which the nitrogen concentration decreases from the outermost surface in the depth direction. Angle Resolved X-ray Photoelectron Spectroscopy (Angle Resolved
It was confirmed by composition analysis in the depth direction using XPS.

The processing conditions, the chemical composition (atomic ratio) and the chemical bonding state of the modified surface 7 in Examples , Reference Examples and Comparative Examples are based on the material for the metal thin film type magnetic tape without the fluorinated lubricant layer 8. X-ray photoelectron spectroscopy (XP
Surface analysis by S), and the results are reference values
As shown in (Table 7).

Each of the 8 samples obtained in the above Examples and Comparative Examples
mm Thin Film Magnetic Tape for VTR (Example
The same measurement as in 1) was performed. The C / N measurement results are shown as relative values based on the C / N value of the magnetic tape produced in Example 2-3 as a reference (0 dB).

Table 8 shows the evaluation results of the metal thin film magnetic tapes for 8 mm VTR manufactured in each of the examples and comparative examples.

[0152]

[Table 8]

As apparent from (Table 7) and (Table 8),
The metal thin-film magnetic tape of the present embodiment does not thermally damage the metal thin-film magnetic tape by irradiating the surface of the ferromagnetic metal thin film with a chemically active species (excited species) containing atomic oxygen. The adhesion between the ferromagnetic metal thin film and the hard carbon film is dramatically improved by forming a dry etching part where only contaminants and low molecular compounds adhering to the surface of the ferromagnetic metal thin film are selectively removed. To improve. Furthermore, a thickness containing an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group (carboxyl group) introduced into the lubricant molecule.
Since the modified surface of less than nm is formed on the hard carbon film, the hardness of the protective film composed of the hard carbon film and the modified surface is not reduced and the spacing between the ferromagnetic metal thin film and the magnetic head is reduced. The lubricant molecules can be firmly held on the tape surface without increasing the loss. In addition, since the nitrogen concentration of the modified surface decreases from the outermost surface in the depth direction (toward the interface with the hard carbon film), the internal stress of the modified surface itself is moderately reduced. In order to form a modified surface on the hard carbon film, the surface of the hard carbon film is exposed to a glow discharge plasma by a mixed gas of a nitrogen-containing organic gas, a hydrocarbon gas and an inorganic gas. By applying the method, it is possible to deposit the chemically active species (reactive species) in the plasma while cleaning the surface of the hard carbon film, thereby further improving the adhesion between the hard carbon film and the modified surface. Becomes possible. Therefore, since the synergistic effect between the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exhibited, the durability, weather resistance, and running stability can be significantly improved. .

In Reference Example 21-1 , the magnetic characteristics of the ferromagnetic metal thin film tended to deteriorate because the thickness of the dry-etched portion was too large, resulting in a decrease in C / N.

In Reference Example 21-2 , since the atomic ratio of oxygen to cobalt and the atomic ratio of oxygen to carbon in the dry-etched portion seemed to be within appropriate ranges , the ferromagnetic metal thin film and hard The adhesion to the carbon film was not improved, and the still life after storage in a high-temperature, high-humidity environment deteriorated.

In Reference Example 21-3 , since the atomic ratio of nitrogen to carbon and the atomic ratio of nitrogen to oxygen on the modified surface are considered to be within appropriate ranges , the hard carbon film and the fluorine-containing lubricant layer The degree of improvement in adhesiveness was small , and still life, still life after storage in a high-temperature, high-humidity environment, and friction coefficient μk after storage in a high-temperature, high-humidity environment tended to deteriorate .

In Reference Example 21-4 , the modified surface was formed as an intermediate layer by the chemical affinity between the nitrogen atom contained in the modified surface and the polar group (carboxyl group) introduced into the lubricant molecule. Although the carbon film and the lubricant layer adhere firmly,
Because the thickness of the modified surface is too large, the synergistic effect of the wear resistance of the hard carbon film and the low shear force of the lubricant layer is not sufficiently exhibited, and still life and still after storage in a high-temperature, high-humidity environment Life tended to deteriorate .

In Reference Example 21-5 , since the Vickers hardness of the carbon film was low, the still life, the still life after storage in a high-temperature, high-humidity environment, and the like tended to deteriorate .

In the above embodiment, the nitrogen concentration of the modified surface 7 is gradually decreased from the outermost surface in the depth direction. However, the case where the nitrogen concentration is continuously decreased is described. Have the same function and effect.

[0160] In Comparative Example 2, in order to dry etching portion is not formed on the ferromagnetic metal thin film surface, dry
Oxygen atoms for cobalt in the etching process
The ratio and atomic ratio of oxygen to carbon are below the appropriate range
To think, dense the ferromagnetic metal thin film and the hard carbon film
The degree of improvement in the adhesion was small , and the still life after storage in a high-temperature, high-humidity environment deteriorated.

(Embodiment 3) Hereinafter , claims 3, 5, 7, 8, and 9 of the third invention will be described.
Embodiment 3 will be described in detail with reference to the drawings. This embodiment is different from ( Embodiment 1) in that the ferromagnetic metal thin film 3, the dry etching portion 5, the hard carbon film 6, and the modified surface 7 are continuously formed in a vacuum. It is in.

FIG. 7 shows a state in which the ferromagnetic metal thin film 3, the dry etching portion 5, the hard carbon film 6, and the modified surface 7 constituting the third ferromagnetic metal thin film type magnetic tape of the present invention are placed in a vacuum. FIG. 2 shows a schematic view of a manufacturing apparatus for continuously forming . In the figure , reference numeral 25 denotes a vacuum chamber, and the pressure inside the vacuum chamber 25 is reduced to 1 × 10 ⁻⁵ torr using a vacuum pump 26.
The gas is exhausted so as to be in a high vacuum state of r. Reference numeral 27 denotes a raw material for a metal thin-film magnetic tape in which the back coat layer 4 is formed on the non-magnetic substrate 1, and is fed from an unwinding roll 28 and four pass rolls 29, 30, 31, 32.
Then, it is taken up by a take-up roll 35 via the outer peripheral surfaces of cylindrical cooling cans 33 and 34. The cooling cans 33 and 34 serve to control the rotation so that the metal thin film type magnetic tape material 27 can be transported at a constant speed.

Reference numeral 36 denotes a crucible.
An evaporation source 37 made of metal is provided. Reference numeral 38 denotes an electron gun for irradiating the evaporation source 37 with an electron beam to heat and dissolve it, thereby generating a vapor flow. Reference numeral 39 denotes a shielding mask for controlling the angle of incidence of the vapor stream on the metal thin film type magnetic tape material 27 so as to be in the range of 70 ° to 40 °. 4
Numeral 0 denotes an oxygen gas inlet for introducing oxygen gas into the vicinity of the end face of the Co metal deposition section.

Reference numeral 41 denotes a discharge tube (non-equilibrium plasma generation space) for forming the dry etching portion 5 on the surface of the ferromagnetic metal thin film 3 of the raw material 27 for a metal thin film type magnetic tape. Is provided with a punching metal discharge electrode 42. Punching metal discharge electrode 42
Is connected to a plasma generation power supply 43. As the plasma generation power supply 43, there are three types: a method of applying only a DC voltage or an AC voltage, and a method of applying a DC voltage and an AC voltage in a superimposed manner. Can be adopted. Reference numeral 44 denotes a material gas inlet for introducing an oxidizing gas into the discharge tube 41.

Reference numeral 45 denotes a discharge tube (non-equilibrium plasma generation space) for forming the hard carbon film 6 on the surface of the dry etching processing section 5 of the metal thin film type magnetic tape material 27.
Inside the discharge tube 45, a pipe-shaped discharge electrode 46 is provided. The pipe-shaped discharge electrode 46 is connected to a plasma generation power supply 47. As the plasma generation power supply 47, a method in which only a DC voltage or an AC voltage is applied, or a method in which a DC voltage and an AC voltage are superimposed. Three types of discharge methods of applying a voltage can be adopted. 48
Is a source gas inlet for introducing a mixed gas (source gas) of a hydrocarbon gas and an inorganic gas such as argon into the discharge tube 45.

Reference numeral 49 denotes a discharge tube (non-equilibrium plasma generation space) for forming the modified surface 7 on the hard carbon film 6, and a punching metal discharge electrode 50 is provided inside the discharge tube 49. . The punching metal discharge electrode 50 is connected to a power supply 51 for plasma generation. The power supply 51 for plasma generation is a method of applying only a DC voltage or an AC voltage, or a method of superimposing a DC voltage and an AC voltage. Three types of discharge methods of applying a voltage can be adopted. Reference numeral 52 denotes a raw material gas inlet for introducing a mixed gas (raw gas) of a nitrogen-containing organic gas and an inorganic gas into the discharge tube 49.

Example 3-1 Surface shape analysis by scanning tunneling microscope (STM) showed that the maximum height roughness (Rmax) was 15 nm and the diameter was 200 n.
The small protrusion layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A backcoat layer 4 having a thickness of 500 nm is formed on the surface on the opposite side of the provided 10 μm-thick polyethylene terephthalate film 1 by a wet coating method.

Next, the raw material 27 for metal thin film magnetic tape is set inside the vacuum chamber 25 of the manufacturing apparatus shown in FIG. 7, and the inside of the vacuum chamber 25 is evacuated. Is transported at a traveling speed of 20 m / min, and a small amount of oxygen is introduced from the oxygen gas inlet 40 into the vacuum chamber 25, and electrons emitted from the electron gun 38 to the evaporation source 37 made of Co metal in the crucible 36. A beam is irradiated to heat and evaporate the evaporation source 37, and the incident angle is 70 ° to 4 °.
In the range of 0 °, a ferromagnetic metal thin film 3 (Co—O vapor-deposited film) having a thickness of 180 nm is formed on the surface of the polyethylene terephthalate film 1 on which the microprojection layer 2 is formed.

Further, an oxygen gas (oxidizing gas: O ₂ ) is introduced into the discharge tube 41, and a DC voltage of 1200 V is applied to the punching metal discharge electrode 18 in a state where the gas pressure is set to 0.2 torr. Is formed, and a dry etching portion 5 is formed to a thickness of 5 nm on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape material 27.

In the discharge tube 45, toluene gas (hydrocarbon gas: C ₇ H ₈ ) and argon gas (inorganic gas: A
r) were introduced, and a DC voltage of 150 was applied to the pipe-shaped discharge electrode 46 with the pressure ratio of toluene gas to argon gas set to 4: 1, and the total gas pressure set to 0.3 torr.
A non-equilibrium plasma is generated by applying 0 V, and a hard carbon film 6 having a thickness of 10 nm is formed on the surface of the dry etching portion 5 of the raw material 27 for a metal thin film magnetic tape.

A pyridine gas (nitrogen-containing organic gas: C ₅ H ₅ N) and a hydrogen gas (inorganic gas: H
₂ ) were introduced, and a DC voltage of 15 was applied to the punching metal discharge electrode 50 with the pressure ratio of pyridine gas to hydrogen gas set to 3: 2 and the total gas pressure set to 0.3 torr.
By applying 00V, non-equilibrium plasma is generated, and a modified surface 7 having a thickness of 1 nm is formed on the surface of the hard carbon film 6 of the metal thin film type magnetic tape material 27.

Next, a fluorine-containing lubricant layer 8 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the modified surface 7 by a wet coating method to a thickness of about 3 nm. And 8 mm wide slits to produce an 8 mm VTR metal thin film magnetic tape.

The Vickers hardness of the hard carbon film 5 obtained in Example 3-1 was 2,700 kg / mm ² .

Example 3-2 The pressure of oxygen gas as a source gas for forming the dry etching section 5 was set to 0.15 torr, and the DC voltage was set to 900.
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Example 3-1 except that the dry etching portion 5 was formed to a thickness of 3 nm by applying V.

Reference Example 31 A ferromagnetic metal thin film 3 was formed in the same manner as in Example 3-1.
7 is left in an environment of 23 ° C. and 60% RH for 3 days, and then the dry etching section 5 and the hard carbon film 6 modified surface 7 are continuously formed in a vacuum in the same manner as in Example 3-1. Except for this , an 8 mm VTR was produced in the same manner as in Example 3-1.
Metal thin film type magnetic tape was prepared.

Comparative Example 3 A ferromagnetic metal thin film 3, a hard carbon film 6, and a modified surface 7 were formed on a surface of a polyethylene terephthalate film 1 on which a microprojection layer 2 was formed in a vacuum without forming a dry etching portion 5. Was formed in the same manner as in Example 3-1 except that the tape was continuously formed.

In the examples , reference examples and comparative examples, the processing conditions and the atomic ratios (O / Co,
O / C) and the chemical bond state of Co atoms, the critical surface tension (γ _C ) of the surface of the dry-etched portion 5, and the Vickers hardness of the hard carbon film 6 were measured in the same manner as in ( Reference Example 1 ). Was. The results are shown in Table 9 as reference values .

[0178]

[Table 9]

The processing conditions, the chemical composition (atomic ratio) and the chemical bonding state of the modified surface 7 in Examples , Reference Examples and Comparative Examples are as follows for the metal thin film type magnetic tape without the fluorinated lubricant layer 8 formed. X-ray photoelectron spectroscopy (X
(PS) surface analysis, and refer to the results
The values are shown in (Table 9).

The following measurements were performed on each of the 8 mm VTR metal thin film magnetic tapes (hereinafter simply referred to as magnetic tapes) obtained in the above Examples , Reference Examples and Comparative Examples. (1) C / N The ratio of the signal (C) at 7 MHz to the noise (N) at 6.5 MHz was measured using an EVS-900 (manufactured by Sony Corporation) as an 8 mm VTR for C / N measurement. The C / N of the magnetic tape produced in Example 3-3 was shown as a relative value with reference (0 dB). (2) Still life Using an 8 mm VTR modified for still life measurement,
A video signal was recorded on each magnetic tape under an environment of 3 ° C. and 10% RH, and was reproduced in a still mode under a load of 30 g. The time until the reproduction output dropped by 6 dB was shown. The measurement was terminated for a maximum of 60 minutes. (3) Weather resistance test The weather resistance test was carried out under an environment of 40 ° C. and 90% RH.
The magnetic tape was allowed to stand for 0 days, and the state of occurrence of rust, peeling, and the like was observed with an optical microscope, and evaluated on a 5-point scale. The evaluation was 5 when there was no practical problem and 1 when there was a practical problem. (4) Reduction rate of Bsδ The Bsδ value of each magnetic tape was measured before and after the weathering test, and the BSδ was measured.
Was determined. (5) Still life after storage in a high-temperature, high-humidity environment Using an 8 mm VTR modified for still life measurement,
A video signal was recorded on each magnetic tape after the weather resistance test in an environment of 3 ° C. and 10% RH, and reproduced in a still mode under a load of 30 g, and the time until the reproduced output dropped by 6 dB was shown. . The measurement was terminated for a maximum of 60 minutes. (6) Stainless steel with a friction coefficient μk of 4 mm in diameter and a surface roughness of 0.2 S (SUS4
20J2) The magnetic layer forming surface of each magnetic tape after the weather resistance test is brought into contact with the cylinder over 90 °, the input side tension is set to 30 g, and the tape traveling speed is set to 0.5 mm / sec with respect to the stainless steel cylinder. The output side tension Xg at the set time was measured, and the friction coefficient was determined from ( Equation 1) .

The measurement environment was 25 ° C.-30% RH, and the measured value in the 30th pass was adopted as the friction coefficient. (7) Running durability test Using an 8 mm VTR modified for RF output measurement, at 23 ° C
Under an environment of -10% RH, a video signal was recorded on each magnetic tape having a length of 60 minutes, and a durability test was performed by repeated running.
The evaluation was based on the output of the first pass of reproduction as a reference (0 dB), and was represented by the number of passes until the reproduction output decreased by 3 dB. The maximum number of repetitions was 300.

Table 10 shows the evaluation results of the metal thin film magnetic tapes for 8 mm VTR produced in each of the examples, reference examples and comparative examples.

[0183]

[Table 10]

As is clear from Tables 9 and 10, the metal thin film type magnetic tape of this example was irradiated with a chemically active species (excited species) containing atomic oxygen on the surface of the ferromagnetic metal thin film. As a result, a dry etching portion is formed in which only contaminants and low molecular compounds adhering to the surface of the ferromagnetic metal thin film are selectively removed without thermally damaging the metal thin film magnetic tape. Therefore, the adhesion between the ferromagnetic metal thin film and the hard carbon film is dramatically improved. Further, since a modified surface having a thickness of less than 3 nm containing an appropriate amount of a nitrogen atom having a strong chemical affinity with the polar group (carboxyl group) introduced into the lubricant molecule is formed on the hard carbon film. To firmly retain lubricant molecules on the tape surface without lowering the hardness of the protective film consisting of the hard carbon film and the modified surface, and without increasing the spacing loss between the ferromagnetic metal thin film and the magnetic head. Can be. In addition, in order to form a modified surface on the hard carbon film, the surface of the hard carbon film is exposed to glow discharge plasma by a mixed gas of a nitrogen-containing organic gas and an inorganic gas to apply a method of forming the modified surface on the hard carbon film. Since the chemically active species (reactive species) in the plasma can be deposited while cleaning, good adhesion between the hard carbon film and the modified surface can be ensured.
Therefore, since the synergistic effect between the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exhibited, the durability, weather resistance, and running stability can be significantly improved. . Furthermore, by continuously forming the ferromagnetic metal thin film, the dry etching portion, the hard carbon film, and the modified surface in a vacuum, the moisture and the like from the atmosphere on the surface of the ferromagnetic metal thin film and the surface of the hard carbon film are reduced. Since the adsorption can be greatly reduced, the reduction rate of Bsδ can be reduced and the running durability can be greatly improved.

In Reference Example 31 , the adsorption rate of moisture and the like from the atmosphere on the surface of the ferromagnetic metal thin film increased the rate of decrease of Bsδ and lowered running durability.

In Comparative Example 3, since no dry-etched portion was formed on the surface of the ferromagnetic metal thin film, the adhesion between the ferromagnetic metal thin film and the hard carbon film was not sufficiently improved.
Bsδ reduction rate, still life after high temperature and high humidity storage,
Running durability deteriorated.

(Embodiment 4) Hereinafter, a fourth aspect of the present invention will be described with reference to claims 4, 5, 6, 7, 8, and 9.
A corresponding embodiment will be described in detail with reference to the drawings. This embodiment is different from the second embodiment in that the ferromagnetic metal thin film 3, the dry etching portion 5, the hard carbon film 6, and the modified surface 7 are continuously formed in a vacuum. .

FIG. 8 shows a ferromagnetic metal thin film 3 and a dry etching processing section 5 and a hard carbon film 6 constituting a ferromagnetic metal thin film type magnetic tape according to a third embodiment of the present invention, and a hard carbon film 6 having a concentration gradient of nitrogen atoms. FIG. 1 is a schematic view of a manufacturing apparatus for continuously forming a quality surface 7 in a vacuum. (That is, it corresponds to the ninth manufacturing method of the ferromagnetic metal thin film type magnetic tape of the present invention.) In the drawing, reference numeral 25 denotes a vacuum tank, and the pressure inside the vacuum tank 25 is 1 × 10 ^{− 5} tor
The gas is exhausted so as to be in a high vacuum state of r. Reference numeral 27 denotes a raw material for a metal thin-film magnetic tape in which the back coat layer 4 is formed on the non-magnetic substrate 1, and is fed from an unwinding roll 28 and four pass rolls 29, 30, 31, 32.
Then, it is taken up by a take-up roll 35 via the outer peripheral surfaces of cylindrical cooling cans 33 and 34. The cooling cans 33 and 34 serve to control the rotation so that the metal thin film type magnetic tape material 27 can be transported at a constant speed.

Reference numeral 36 denotes a crucible.
An evaporation source 37 made of metal is provided. Reference numeral 38 denotes an electron gun for irradiating the evaporation source 37 with an electron beam to heat and dissolve it, thereby generating a vapor flow. Reference numeral 39 denotes a shielding mask for controlling the angle of incidence of the vapor stream on the metal thin film type magnetic tape material 27 so as to be in the range of 70 ° to 40 °. 4
Numeral 0 denotes an oxygen gas inlet for introducing oxygen gas into the vicinity of the end face of the Co metal deposition section.

Reference numeral 41 denotes a discharge tube (non-equilibrium plasma generation space) for forming the dry etching section 5 on the surface of the ferromagnetic metal thin film 3 of the raw material 27 for the metal thin film type magnetic tape. Is provided with a punching metal discharge electrode 42. Punching metal discharge electrode 42
Is connected to a plasma generation power supply 43. As the plasma generation power supply 43, there are three types: a method of applying only a DC voltage or an AC voltage, and a method of applying a DC voltage and an AC voltage in a superimposed manner. Can be adopted. Reference numeral 44 denotes a material gas inlet for introducing an oxidizing gas into the discharge tube 41.

Reference numeral 45 denotes a discharge tube (non-equilibrium plasma generation space) for forming the hard carbon film 6 on the surface of the dry etching processing portion 5 of the metal thin film type magnetic tape material 27.
Inside the discharge tube 45, a pipe-shaped discharge electrode 46 is provided. The pipe-shaped discharge electrode 46 is connected to a plasma generation power supply 47. As the plasma generation power supply 47, a method in which only a DC voltage or an AC voltage is applied, or a method in which a DC voltage and an AC voltage are superimposed. Three types of discharge methods of applying a voltage can be adopted. 48
Is a source gas inlet for introducing a mixed gas (source gas) of a hydrocarbon gas and an inorganic gas such as argon into the discharge tube 45.

Reference numerals 53, 54, and 55 denote discharge tubes (non-equilibrium plasma generation spaces) for forming the modified surface 7 on the hard carbon film 6. Punching metal is provided inside the discharge tubes 53, 54, and 55. Discharge electrodes 56, 57, 58 are provided respectively. Punching metal discharge electrodes 56, 57, 5
Numeral 8 is connected to plasma generation power supplies 59, 60, 61, respectively. As the plasma generation power supplies 59, 60, 61, a method of applying only a DC voltage or an AC voltage, a DC voltage and an AC voltage, , And three types of discharge methods, i. 6
2, 63 and 64 are nitrogen-containing organic gases, hydrocarbon gases,
A mixed gas (raw material gas) composed of an inorganic gas is supplied to the discharge tube 5
These are raw material gas inlets for introducing into 3, 54 and 55, respectively.

Example 4-1 Surface height analysis by scanning tunneling microscope (STM) showed that the maximum height roughness (Rmax) was 15 nm and the diameter was 200 n.
The small protrusion layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A backcoat layer 4 having a thickness of 500 nm is formed on the surface on the opposite side of the provided 10 μm-thick polyethylene terephthalate film 1 by a wet coating method.

Next, the raw material 27 for metal thin film magnetic tape is set inside the vacuum chamber 25 of the manufacturing apparatus shown in FIG. 8, and the inside of the vacuum chamber 25 is evacuated. Is transported at a traveling speed of 20 m / min, and a small amount of oxygen is introduced from the oxygen gas inlet 40 into the vacuum chamber 25, and electrons emitted from the electron gun 38 to the evaporation source 37 made of Co metal in the crucible 36. A beam is irradiated to heat and evaporate the evaporation source 37, and the incident angle is 70 ° to 4 °.
In the range of 0 °, a ferromagnetic metal thin film 3 (Co—O vapor-deposited film) having a thickness of 180 nm is formed on the surface of the polyethylene terephthalate film 1 on which the microprojection layer 2 is formed.

Further, an oxygen gas (oxidizing gas: O ₂ ) is introduced into the discharge tube 41, and a DC voltage of 1200 V is applied to the punching metal discharge electrode 18 in a state where the gas pressure is set to 0.2 torr. Is formed, and a dry etching portion 5 is formed to a thickness of 5 nm on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape material 27.

Further, toluene gas (hydrocarbon-based gas: C ₇ H ₈ ) and argon gas (inorganic-based gas: A
r) were introduced, and a DC voltage of 150 was applied to the pipe-shaped discharge electrode 46 with the pressure ratio of toluene gas to argon gas set to 4: 1, and the total gas pressure set to 0.3 torr.
A non-equilibrium plasma is generated by applying 0 V, and a hard carbon film 6 having a thickness of 10 nm is formed on the surface of the dry etching portion 5 of the raw material 27 for a metal thin film magnetic tape.

Further, n-propylamine gas (nitrogen-containing organic gas: C ₃ H ₉ N), methane gas (hydrocarbon gas: CH ₄ ), and hydrogen gas (inorganic gas: H ₂ ) were introduced, and in the discharge tube 53, the discharge was performed with the pressure ratio of n-propylamine gas, methane gas, and hydrogen gas set to 2: 7: 1 and the total gas pressure set to 0.3 torr. In the pipe 54, the pressure ratio of n-propylamine gas, methane gas, and hydrogen gas is set to 4.
In a state where the gas pressure is set to 5: 4.5: 1 and the total gas pressure is set to 0.3 torr, the pressure ratio of n-propylamine gas, methane gas and hydrogen gas is set to 7: 2:
1. With a total gas pressure set to 0.3 torr, a DC voltage of 2000 V is applied to the punching metal discharge electrodes 56, 57, and 58 to generate non-equilibrium plasma, and the material 27 for the metal thin film magnetic tape is produced. Thickness 2n in which the nitrogen concentration decreases from the outermost surface in the depth direction (in the direction of the interface with the hard carbon film 6) on the surface of the hard carbon film 6
m modified surface 7 is formed.

Next, a fluorine-containing lubricant layer 8 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the modified surface 7 by a wet coating method to a thickness of about 3 nm. And 8 mm wide slits to produce an 8 mm VTR metal thin film magnetic tape.

The Vickers hardness of the hard carbon film 5 obtained in Example 4-1 was 2,700 kg / mm ² .

Example 4-2 The pressure of oxygen gas as a source gas for forming the dry etching section 5 was set to 0.15 torr, and the DC voltage was set to 900
An 8 mm VTR metal thin film magnetic tape was manufactured in the same manner as in Example 4-1 except that the dry etching portion 5 was formed to a thickness of 3 nm by applying V.

Reference Example 41 A ferromagnetic metal thin film 3 was formed in the same manner as in Example 4-1.
7 in a 23 ° C.-60% RH environment for 3 days,
An 8 mm VTR was produced in the same manner as in Example 4-1 except that the dry etching portion 5, the hard carbon film 6 and the modified surface 7 were continuously formed in a vacuum in the same manner as in Example 4-1.
Metal thin film type magnetic tape was prepared.

Comparative Example 4 A ferromagnetic metal thin film 3, a hard carbon film 6, and a modified surface 7 were formed on a surface of a polyethylene terephthalate film 1 on which a microprojection layer 2 was formed in a vacuum without forming a dry etching portion 5. Was formed in the same manner as in Example 4-1 except that the metal thin film magnetic tape for 8 mm VTR was used.

[0203] Example, the process conditions and the atomic ratio of dry etching unit 5 in the Reference Examples and Comparative Examples (O / Co,
The chemical bonding state of O / C) and Co atoms, the critical surface tension (γ _C ) of the surface of the dry etching treatment section 5 and the Vickers hardness of the hard carbon film 6 were measured by the same method as in (Reference Example 1). Was. Using the results as reference values (Table 1
Shown in 1).

[0204]

[Table 11]

In the embodiment and the comparative example, the modified surface 7 formed on the surface of the hard carbon film 6 has a structure in which the nitrogen concentration decreases from the outermost surface in the depth direction. X-ray photoelectron spectroscopy (Angle Resolved XP
It was confirmed by a composition analysis in the depth direction using S).

The processing conditions, the chemical composition (atomic ratio) and the chemical bonding state of the modified surface 7 in Examples, Reference Examples and Comparative Examples are as follows for the metal thin film type magnetic tape without the fluorine-containing lubricant layer 8 formed. X-ray photoelectron spectroscopy (X
(PS) surface analysis, and refer to the results
The values are shown in (Table 11).

Each of the 8 samples obtained in the above Examples and Comparative Examples
mm Thin Film Magnetic Tape for VTR (Example
The same measurement as in 3) was performed. The C / N measurement results are shown as relative values based on the C / N value of the magnetic tape produced in Example 3-3 (0 dB).

Table 12 shows the evaluation results of the metal thin film magnetic tapes for 8 mm VTR manufactured in the respective examples and comparative examples.

[0209]

[Table 12]

As is clear from Tables 11 and 12, the metal thin film type magnetic tape of this example was irradiated with a chemically active species (excited species) containing atomic oxygen on the surface of the ferromagnetic metal thin film. As a result, a dry etching portion is formed in which only contaminants and low molecular compounds adhering to the surface of the ferromagnetic metal thin film are selectively removed without thermally damaging the metal thin film magnetic tape. Therefore, the adhesion between the ferromagnetic metal thin film and the hard carbon film is dramatically improved. Further, since a modified surface having a thickness of less than 3 nm containing an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group (carboxyl group) introduced into the lubricant molecule is formed on the hard carbon film. To firmly retain lubricant molecules on the tape surface without lowering the hardness of the protective film consisting of the hard carbon film and the modified surface, and without increasing the spacing loss between the ferromagnetic metal thin film and the magnetic head. Can be. In addition, since the nitrogen concentration of the modified surface decreases from the outermost surface in the depth direction (toward the interface with the hard carbon film), the internal stress of the modified surface itself is moderately reduced. In order to form a modified surface on the hard carbon film, the surface of the hard carbon film is exposed to a glow discharge plasma by a mixed gas of a nitrogen-containing organic gas, a hydrocarbon gas and an inorganic gas. By applying the method, it is possible to deposit the chemically active species (reactive species) in the plasma while cleaning the surface of the hard carbon film, thereby further improving the adhesion between the hard carbon film and the modified surface. Becomes possible. Therefore, since the synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exhibited, durability, weather resistance,
Driving stability has been dramatically improved.
Furthermore, by continuously forming the ferromagnetic metal thin film, the dry etching portion, the hard carbon film, and the modified surface in a vacuum, the moisture and the like from the atmosphere on the surface of the ferromagnetic metal thin film and the surface of the hard carbon film are reduced. Since the adsorption can be greatly reduced, the reduction rate of Bsδ can be reduced and the running durability can be greatly improved.

In Reference Example 41 , the adsorption rate of moisture and the like from the air on the surface of the ferromagnetic metal thin film increased the rate of decrease of Bsδ and lowered running durability.

In Comparative Example 4 , since no dry-etched portion was formed on the surface of the ferromagnetic metal thin film, the adhesion between the ferromagnetic metal thin film and the hard carbon film was not sufficiently improved.
Bsδ reduction rate, still life after high temperature and high humidity storage,
Running durability deteriorated.

In the above embodiment, only the metal thin film type magnetic tape for 8 mm VTR has been described. However, the present invention is not limited to this, and other magnetic recording media such as ferromagnetic metal thin film type magnetic tapes and magnetic disks can be used. The same applies.

In the above embodiment, only the case where plasma etching is used as an etching mode for forming a dry etching portion is described. However, the present invention is not limited to this mode. The dry etching mode can be similarly performed.

In the above embodiment, when the dry etching portion is formed by plasma etching, the surface of the ferromagnetic metal thin film is irradiated with an oxidizing gas for generating chemically active species (excited species) containing atomic oxygen. Although only the case where oxygen is used has been described, the present invention is not limited to this, and the same can be applied to other oxidizing gases.

In the above embodiment, only the method of applying only a DC voltage as a discharge type when forming a dry etching portion by plasma etching has been described. However, the present invention is not limited to this method. A method in which an AC voltage is superimposed and applied and a method in which only an AC voltage is applied can be similarly implemented.

In the above embodiment, pyridine, allylamine, and n-containing organic gas are used as the source gas for generating the glow discharge plasma for irradiating the surface of the hard carbon film (ie, the source gas for forming the modified surface). Although only the case where -propylamine is used is shown, the present invention is not limited thereto, and the same applies to any organic monomer gas containing a nitrogen atom in the molecule. As for the inorganic gas, only the case where H ₂ and NH ₃ are used is shown. However, the present invention is not limited thereto, and the same applies to Ar, He, N ₂ and O ₂ other than the above gases. . Although only the case where methane gas is used as one of the source gases for forming the reformed surface having a concentration gradient of nitrogen atoms is shown, the present invention can be similarly applied to other hydrocarbon gases.

Further, in the above embodiment, the modified surface is formed by the plasma C
Although only a method of applying a DC voltage as a discharge type when forming by the VD method has been described, the present invention is not limited to this method, and a method of applying a DC voltage and an AC voltage in a superposed manner and an AC voltage only Can be similarly implemented.

In the above embodiment, the hard carbon film is formed by the plasma CVD method. However, the present invention is not limited to this method, and an ion beam evaporation method, an ion beam sputtering method, a laser evaporation method, or the like may be used. It can be implemented similarly.

Further, in the above-described embodiment, only a method of applying a DC voltage as a discharge type when a hard carbon film is formed by a plasma CVD method has been described. However, the present invention is not limited to this method. A method in which an AC voltage is superimposed and applied and a method in which only an AC voltage is applied can be similarly implemented.

In the above examples, only the fluorinated lubricant in which a carboxyl group was introduced as a polar group into the molecule was shown, but -OH, -SH, -NH ₂ , = NH,-
_{NCO, -CONH 2, -CONHR, -CONR} 2,
-COOR, = PR, = PRO, = PRS, -OPO
(OH) ₂ , —OPO (OR) ₂ , —SO ₃ M (where R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal) The same applies to a fluorine-containing lubricant having a polar group.

In the above embodiment, the ferromagnetic metal thin film is formed by the vacuum evaporation method. However, the present invention is not limited to this manufacturing method, and an ion plating method, a sputtering method, or the like can be used. is there.

[0223]

As described above, according to the present invention, a ferromagnetic metal thin film is formed on a nonmagnetic substrate, and the surface of the ferromagnetic metal thin film is irradiated with a chemically active species (excited species) containing at least atomic oxygen. After providing a dry etching processing part containing more oxygen atoms in the surface layer of the ferromagnetic metal thin film than other parts,
A hard carbon film is formed, and the surface of the hard carbon film is exposed to glow discharge plasma by a mixed gas of a nitrogen-containing organic gas and an inorganic gas, thereby containing carbon, nitrogen and oxygen on the hard carbon film.
Forming a non-modified surface, further manufacturing method for forming a lubricant layer on the modified surface, or a ferromagnetic metal thin film formed on a nonmagnetic substrate, at least atomic oxygen in the ferromagnetic metal thin film surface A hard carbon film is formed by irradiating the surface layer of the ferromagnetic metal thin film with a chemically etched species (excited species) to form a hard carbon film after providing a dry etching portion containing more oxygen atoms than other portions. By exposing the film surface to glow discharge plasma with a mixed gas of nitrogen-containing organic gas, hydrocarbon gas and inorganic gas, carbon, nitrogen and oxygen are contained on the hard carbon film , and the nitrogen concentration becomes Decreases in the direction
Forming a modified surface to be formed, further by a manufacturing method of forming a lubricant layer on this modified surface, electromagnetic conversion characteristics, running stability,
It is possible to provide a magnetic recording medium having excellent durability and weather resistance, and its practical value is large.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a configuration of a ferromagnetic metal thin film type magnetic tape of Examples 1 to 4 in the present invention.

FIG. 2 is an enlarged cross-sectional view showing the configuration of a ferromagnetic metal thin film type magnetic tape according to Reference Examples 1 and 2 of the present invention.

FIG. 3 is a schematic view of a dry etching processing part constituting a ferromagnetic metal thin film type magnetic tape corresponding to the first embodiment of the present invention and a manufacturing apparatus for continuously forming a hard carbon film in a vacuum.

FIG. 4 is a diagram illustrating a method for continuously forming a ferromagnetic metal thin film, a dry-etched portion, and a hard carbon film in a vacuum in a ferromagnetic metal thin film magnetic tape according to a second embodiment of the present invention. Schematic diagram of the device

FIG. 5 is a manufacturing apparatus for continuously forming a dry-etched portion, a hard carbon film, and a modified surface constituting a ferromagnetic metal thin film type magnetic tape according to the first embodiment of the present invention in a vacuum; Schematic diagram of

FIG. 6 shows a dry-etched portion, a hard carbon film, and a modified surface having a concentration gradient of nitrogen atoms constituting a ferromagnetic metal thin-film type magnetic tape corresponding to Example 2 of the present invention continuously in vacuum. Schematic diagram of manufacturing equipment for forming into

FIG. 7: A ferromagnetic metal thin film, a dry etching portion, a hard carbon film and a modified surface constituting a ferromagnetic metal thin film type magnetic tape corresponding to Embodiment 3 of the present invention are continuously formed in a vacuum. Schematic diagram of manufacturing equipment for performing

FIG. 8 shows a ferromagnetic metal thin film, a dry-etched portion, a hard carbon film, and a modified surface having a concentration gradient of nitrogen atoms, which constitute a ferromagnetic metal thin film magnetic tape according to Example 4 of the present invention. Schematic diagram of manufacturing equipment for continuous formation in vacuum

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic substrate 2 Micro protrusion layer 3 Ferromagnetic metal thin film 4 Back coat layer 5 Dry etching processing part 6 Hard carbon film 7 Modified surface 8 Fluorine-containing lubricant layer 9 Vacuum tank 10 Vacuum pump 11 Metal thin film type magnetic tape Raw material 12 Unwind roll 13 Pass roll 14 Pass roll 15 Cooling can 16 Take-up roll 17 Discharge tube 18 Punching metal discharge electrode 19 Plasma generation power supply 20 Source gas inlet 21 Discharge tube 22 Pipe-shaped discharge electrode 23 Plasma generation power supply 24 Source gas inlet 25 Vacuum tank 26 Vacuum pump 27 Material roll for metal thin film magnetic tape 28 Unwind roll 29 Pass roll 30 Pass roll 31 Pass roll 32 Pass roll 33 Cooling can 34 Cooling can 35 Rewind roll 36 Crucible 37 Evaporation source 38 Electron gun 39 Shielding mass Reference Signs List 40 oxygen gas inlet 41 discharge tube 42 punching metal discharge electrode 43 power supply for plasma generation 44 source gas inlet 45 discharge tube 46 pipe-shaped discharge electrode 47 plasma generation power supply 48 source gas inlet 49 discharge tube 50 punching metal discharge electrode Reference Signs List 51 Power supply for plasma generation 52 Source gas inlet 53 Discharge tube 54 Discharge tube 55 Discharge tube 56 Punching metal discharge electrode 57 Punching metal discharge electrode 58 Punching metal discharge electrode 59 Power supply for plasma generation 60 Power supply for plasma generation 61 Power supply for plasma generation 62 Source gas inlet 63 Source gas inlet 64 Source gas inlet

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C23F 4/00 C23F 4/00 A G11B 5/851 G11B 5/851 (72) Inventor Mikio Murai 1006 Odakadoma, Kazuma, Osaka Matsushita Electric (72) Inventor Kiyoji Takahashi 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor: Yu Odagi 1006 Kadoma Kadoma, Kadoma City, Osaka Pref. 72) Inventor Yoshiyuki Okazaki 1006 Kazuma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-175925 (JP, A) JP-A-5-298682 (JP, A) JP JP-A-3-238620 (JP, A) JP-A-1-263912 (JP, A) JP-A-2-12614 (JP, A) JP-A-57-179949 (JP, A) JP-A-61-151830 (JP) , A) JP-A-61-117728 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/62-5/858 C23C 14/06 C23C 16/26-16/50 C23F 4/00

Claims (9)

(57) [Claims] A ferromagnetic metal thin film formed on a non-magnetic substrate,
After irradiating the surface of the ferromagnetic metal thin film with a chemically active species (excited species) containing at least atomic oxygen in a vacuum to provide a dry etching portion, a hard carbon film is formed without breaking the vacuum, Furthermore, the lubricant layer is formed after forming the modified surface by exposing the surface of the hard carbon film to a glow discharge plasma with a mixed gas of a nitrogen-containing organic gas and an inorganic gas without breaking vacuum. A method for manufacturing a magnetic recording medium. 2. A ferromagnetic metal thin film is formed on a non-magnetic substrate,
After irradiating the surface of the ferromagnetic metal thin film with a chemically active species (excited species) containing at least atomic oxygen in a vacuum to provide a dry etching portion, a hard carbon film is formed without breaking the vacuum, Further, after forming the modified surface by exposing the surface of the hard carbon film to a glow discharge plasma with a mixed gas of a nitrogen-containing organic gas, a hydrocarbon-based gas, and an inorganic gas without breaking the vacuum, a lubricant layer is formed. A method for manufacturing a magnetic recording medium. 3. A method of forming a ferromagnetic metal thin film on a non-magnetic substrate by a vacuum deposition method, an ion plating method, or a sputtering method, wherein the surface of the ferromagnetic metal thin film contains at least atomic oxygen without breaking vacuum. After irradiating a seed (excited species) with a dry etching treatment part, a hard carbon film is formed without breaking vacuum, and the surface of the hard carbon film is further broken without breaking a vacuum. A method for manufacturing a magnetic recording medium, comprising: forming a modified surface by exposing to a glow discharge plasma by a mixed gas with a system gas; and then forming a lubricant layer. 4. A ferromagnetic metal thin film is formed on a non-magnetic substrate by a vacuum deposition method, an ion plating method, or a sputtering method, and the surface of the ferromagnetic metal thin film contains at least atomic oxygen without breaking vacuum. After irradiating a seed (excited species) with a dry etching treatment part, a hard carbon film is formed without breaking vacuum, and the hard carbon film surface is carbonized with a nitrogen-containing organic gas without breaking vacuum. A method for manufacturing a magnetic recording medium, comprising: forming a modified surface by exposing to a glow discharge plasma of a mixed gas of a hydrogen-based gas and an inorganic gas; and then forming a lubricant layer. 5. The dry etching section according to claim 1, wherein the surface of the ferromagnetic metal thin film is exposed to a glow discharge plasma generated by an oxidizing gas. A method for manufacturing a magnetic recording medium. 6. A modified surface is formed by sequentially exposing the surface of the hard carbon film to glow discharge plasma by a mixed gas in which a ratio of a nitrogen-containing organic gas to a hydrocarbon-based gas is gradually increased. The method for manufacturing a magnetic recording medium according to claim 2 or 4 , wherein: 7. The inorganic gas includes Ar, He, H ₂ ,
N _2, O _2, The method of manufacturing a magnetic recording medium according to any one of claims 1,2,3,4,6, characterized by using one or more materials selected from NH _3. 8. claims 1,2,3,4,6,7, characterized in that the nitrogen-containing organic gas partial pressure for forming the modified surface and 20 to 70% of the total gas pressure A method for manufacturing a magnetic recording medium according to any one of the preceding claims. 9. A lubricant layer comprising -COOH, -OH, -S
_{H, -NH 2,> NH,} -CONH 2, -CONHR,
_{-CONR 2, -COOR,> PR,} >PRO,> PR
S, -OPO (OH) ₂ , -OPO (OR) ₂ , -SO
₃ M (where R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal) is a fluorinated lubricant layer having at least one kind of polar group selected from The method for manufacturing a magnetic recording medium according to claim 1 , wherein: