JP2000104170A - Formation of coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a hard carbon film high in reliability on the surface of a magnetic recording medium having an electrically conductive metallic magnetic layer by subjecting the surface of a magnetic material to plasma activating treatment. SOLUTION: Plasma is composed of gaseous hydrogen, gaseous argon or a gaseous mixture of hydrogen and argon, the magnetic material is a metallic magnetic material, moreover, the magnetic material is composed of a Co-Cr-Ni alloy, and, furthermore, plasma of methane or alcohol as a gaseous starting material is generated to form a carbon film. Preferably, the thickness of the carbon film is 50 to 2000 Å, moreover, the carbon film is specified by using a Raman spectrum, and, furthermore, the carbon film is composed of diamondlike carbon. A plasma generating device is composed of a center conductor 31, an outer conductor 29, a cylindrical insulator 33 or the like, a rare gas and the gaseous mixture pass through a clearance 32, and, at the clearance 32, it is made to be plasma. Then, beam-shaped plasma is jetted to the outside of the device, and a film is formed by the activated gaseous starting material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing apparatus and method for forming a magnetic recording medium having high durability, high recording density, and excellent mass productivity on a polymer substrate material. In particular, the present invention relates to an apparatus and a method for forming a protective film that requires functions of wear resistance and lubricity. Its industrial application fields cover a wide variety of fields, such as video equipment and information equipment.

[0002]

2. Description of the Related Art In recent years, the density of magnetic recording media has been increasing. Examples of conventional magnetic recording media include audio,
Γ-Fe ₂ O ₃ powder used for video tape material,
A coating type in which CrO powder, pure iron powder, or the like is coated on a polymer substrate material together with an abrasive and a binder is known. For a magnetic recording medium having higher performance, a magnetic recording material having a metal magnetic material deposited thereon is used.

Further, a technique of forming a film containing carbon as a main component (also called a carbon film, DLC or hard carbon film) on the surface of these magnetic recording media to impart surface protection, wear resistance or lubricity. It has been known. The coating containing carbon as a main component is generally formed by a CVD method typified by a plasma CVD method.

In a typical plasma CVD method, a substrate is placed on a high-frequency voltage supply side (cathode), and a high hardness film is formed using a self-bias formed near the cathode. Generally, a carbon film having high hardness cannot be formed on the ground electrode (anode) side.

[0005] In the case of forming a film containing carbon as a main component by using a parallel plate type plasma CVD method, an organic resin substrate serving as a base of a magnetic storage medium must be provided on a cathode electrode side. Since a magnetic recording medium for high-density recording is generally obtained by evaporating a metal magnetic material, contacting such a base with a cathode electrode causes the base to be a part of the electrode and leaks a high-frequency electric field, which is not preferable. Discharge occurs in the region. Such discharge has a high possibility of damaging the organic resin film as a base, and has a problem in terms of production stability and reliability.

Further, if a hard carbon film as a protective film is to be formed simultaneously with the roll-to-roll type magnetic layer manufacturing process, the film forming speed of the carbon film is too slow to be possible.

Conventionally, a technique of forming a diamond-like carbon film has been known. This diamond-like carbon film is a carbon film having a diamond structure, and is also called a diamond-like carbon (DLC) film. Hereinafter, such a carbon coating is referred to as a hard carbon coating.

[0008] Such a hard carbon coating is coated on the surface of a resin or polymer film and can be used as a wear-resistant layer or a protective film. As a method for forming such a hard carbon film, a film forming apparatus as shown in FIG. 11 is known. In the film formation apparatus illustrated in FIG. 11, a pair of electrodes 112 and 114 are provided in a vacuum vessel 111, and one electrode 112 is connected to a high-frequency (generally 13.56 MHz) power supply 115 and one electrode 114 is grounded. The substrate or base on which the film is formed is indicated by 113 and is disposed on the electrode 112 side to which high-frequency power is supplied. Although not shown, a supply system and an exhaust system for the reactive gas, and a matching device for power supply are provided.

In the plasma CVD apparatus shown in FIG. 11, electrons are charged on the electrode side to which the high-frequency power supply is connected, that is, on the electrode side opposite to the ground electrode, and further on the substrate side. H that contributes to high quality film
⁺ Ions and H radicals collide to form a carbon film having a diamond structure.

[0010] Such a hard carbon film can be used as a protective film for a magnetic recording medium such as a magnetic tape or a magneto-optical disk. These magnetic recording media use a magnetic material and need to be protected in order to prevent foreign substances from entering or being damaged.

As such a technique, Japanese Patent Publication No. 3-239
There is a technique as described in Japanese Patent Application Laid-Open No. 73-73. This publication discloses that a DC bias is applied in addition to a high-frequency discharge so that pinholes of 10 ² to 10 ⁵ / mm ^{2 are formed.}
It describes that the formed carbon film is formed on the surface of a magnetic recording medium.

However, according to the experiments performed by the present inventors, it has been found that a hard carbon film having a pinhole lacks long-term reliability as a protective film because moisture or the like enters the pinhole. There was found. Also, to eliminate the hardness and adhesion of the hard carbon coating and the existence of pinholes,
It turns out that they are not always compatible.

SUMMARY OF THE INVENTION The main object of the present invention is to:
It is an object of the present invention to provide an apparatus capable of stably and reliably producing a hard carbon film on the surface of a magnetic recording medium having a conductive metal magnetic layer.

That is, there is provided an apparatus capable of forming a carbon film having sufficient wear resistance and lubricity in a state in which the carbon film is in contact with an anode serving as a ground electrode.

Another object of the present invention is to provide a hard carbon film as a protective film at the same time as the magnetic layer forming process.
An object of the present invention is to provide an apparatus capable of high-speed film formation.

A further object of the present invention is to provide an apparatus capable of suppressing the generation of flakes due to contamination of electrodes, which is a new problem caused by achieving high-speed film formation.

Another object of the present invention is to form a hard carbon coating having high density, high hardness and adhesion and having few pinholes as a protective film of a magnetic recording medium.

[0017]

According to the present invention, a first electrode to which electromagnetic energy is applied and a grounded second electrode are arranged to face each other, and the first and second electrodes are applied by applying a high-frequency electric field. In a film forming apparatus for generating a plasma between two electrodes and activating a source gas introduced into the plasma to form a film, a distance between the first electrode and the second electrode is 6 mm or less; And the pressure between the electrodes is 15 To
A film forming apparatus characterized by being between rr and 100 Torr.

As the electromagnetic energy, a frequency of several tens KHz to several GHz can be used. Generally, 1
A high frequency of 3.56 MHz is used. Also, a combination of a plurality of frequencies may be used as the electromagnetic energy. For example, an extremely low frequency of 1 to 200 Hz and 1 KH
A method of combining low frequency of z to 1 MHz and high frequency of 10 to 100 MHz to obtain electromagnetic energy may be adopted. That is, a method of combining a plurality of characteristics of each frequency may be adopted.

Further, according to the present invention, the distance between the first and second electrodes is 6 mm or less, and the pressure is from 15 Torr to 10 mm.
The main point is that if it is between 0 Torr, it is possible to form a carbon film with high hardness even if the substrate is in contact with the second electrode, which is a ground electrode. It is.

Prior to the above findings, the present inventor generally
Pressure range selected by plasma CVD (10 mTorr
Pressure region (5 Torr)
From 760 Torr). The reason for focusing on such a higher pressure range than generally conceivable is that it is desired to improve the film formation rate of ordinary plasma CVD by orders of magnitude.

Considering the film formation elementary process (generation of radicals, transport to the substrate surface, reaction on the surface) in plasma CVD, (1) improvement of radical density as a precursor of film formation (2) radical It can be understood that the film formation rate can be improved if the two points of improving the efficiency of transport to the substrate surface can be improved. In the case of plasma CVD, radicals are generated in the entire plasma space, and it can be inferred that generation of radicals has a greater effect on the film formation rate than transport of radicals. It can be expected that the radical density can be increased by increasing the reaction pressure. That is,
Film formation in a high pressure region can be expected to be high-speed film formation.

In the elementary process of film formation, (3) a reaction on the film surface (suppression of surface desorption) can be considered. However, in the case of a low-temperature process such as plasma CVD, the surface reaction does not become rate-determining. The reaction process on the film surface does not contribute to the film formation rate. However, when a hard carbon film is formed, the action of ions on the surface greatly affects the film quality. That is, in the case of a hard carbon film, bombardment of ions is positively applied during film formation, leaving strong bonds in the film and forming films while cutting weak bonds. Therefore, in general, a substrate is provided on the cathode side, and a film is formed using a self-bias.

Even if the radical density is increased by increasing the pressure during film formation, it is meaningless if the physical properties of the plasma, which is the premise of radical generation, are significantly changed by the pressure increase. Therefore, as described above, the present inventors observed plasma in a high pressure region (5 Torr to 760 Torr).

First, a high pressure region (from 5 Torr to 76
0 Torr). Conventionally, low-pressure glow discharge has been reduced from 10 mTorr to 1 T
The discharge was generated in the orr pressure region because a discharge is most easily generated in the pressure region (that is, the discharge is stable). The number of times particles present between parallel plate electrodes with a certain electrode spacing d (d = several tens of mm in the case of a normal low pressure glow) collide with electrons (the electrons are accelerated by the electric field between the electrodes, and from one electrode Flying in the direction of one electrode) is proportional to the pressure of the atmosphere (inversely proportional to the mean free path). In other words, when the pressure is low and the number of collisions is small, the electrons have sufficient energy,
If the particles collide, ionization of the particles occurs, but the particles themselves are small due to the low pressure and cannot be turned into plasma. On the other hand, if the pressure is high, the number of collisions of the electrons increases, and the electrons cannot have sufficient energy before the next collision, and the particles cannot be ionized by the collision. This is known as Paschen's law, in which the firing voltage V is a function of the product of the pressure p and the electrode spacing d (pd product), and the minimum firing voltage Vmin exists at a certain pd product value. It is to do.

That is, in order to generate plasma in a high pressure region, it is necessary to apply an electric field to the electrons sufficient to ionize particles during a short free path. This can be dealt with by reducing the electrode interval d and increasing the voltage applied between the electrodes.

However, there is a limit to the effect of increasing the voltage applied between the electrodes. That is, in the case of the glow discharge, the electric field distribution in the plasma is not uniform, and the electric field is applied most to the sheath formed near the electrode. Next, it is applied to the positive column following the sheath. The length of the sheath portion is about the Debye length peculiar to the plasma, and the electric field is not applied so much to the positive column that occupies most of the space. Therefore, even if a large voltage is applied between the electrodes, a substantial increase in the electric field in the positive column that occupies most of the space cannot be expected. However, since the increase in the voltage between the electrodes is applied to the sheath, ionization in the region is promoted. When the electric field applied to the sheath portion exceeds the limit, accelerated electrons collide with the electrode surface, and thermionic electrons are emitted from the electrode by heating the electrode. In the case of glow discharge, the electron emission mechanism from the electrode is field emission and secondary electron emission.When thermionic emission occurs, the electric field used for electron emission from the electrode almost disappears, and the electric field corresponding to that is reduced by the sheath part. Will be taken. In such a case, the electrons in the sheath are further accelerated to heat the electrode, and thermal runaway occurs as long as the electrode potential is maintained. Such a state is a negative resistance, and when a current flows over all the paths, the state shifts to arc discharge.

Therefore, it is effective to reduce the electrode interval for plasma generation in a high pressure region. However, there is also a lower limit value of the electrode interval. In order for the plasma to exist, the electrode spacing must be at least several times the Debye distance. The Debye distance λ is represented by the following equation. λ = (ε ₀ κ Te / q ² Ne) ^1/2 where ε ₀ is the dielectric constant of vacuum κ is the Boltzmann constant q is the elementary charge amount Te is the electron temperature Ne is the charge density. The plasma of the present invention has an electron density of 10 ¹⁵ / m ³ ,
Since the electron temperature is about 2 eV, the Debye distance is about 0.3 mm. Therefore, it is desirable that the electrode interval is 1 mm or more.

As described above, 1 Torr to 760 Torr
Discharge at pressures up to r is possible, but the physical properties of the plasma change significantly. About 100 Torr to 760 To
In the rr pressure range, the discharge tends to become unstable in the normal electrode structure, as shown in the transition mechanism to the arc discharge described above. Then, the atmospheric pressure discharge generating method which is another invention of the present inventor can be used.

A heat-resistant dielectric is inserted into the electrode surface so that even if the discharge shows negative resistance, the whole system does not show negative resistance. Since the dielectric has a positive resistance, the whole system has a positive resistance. In this case, since the dielectric enters the series in terms of an equivalent circuit, the electric field applied between the electrodes needs to be an alternating current.

Further, in this region, the pressure is high, the probability of collision and recombination of ions and electrons in space increases, and the plasma is easily extinguished. Therefore, it is necessary to promote the diffusion of ions and electrons (particularly the diffusion of ions) to spread the plasma. For this purpose, the addition of a rare gas having a metastable state, particularly helium or argon, is effective. The rare gas is preferably at least 80% of the total gas.

It is also effective to diffuse the particles constituting the plasma by applying a magnetic field. The distribution of the magnetic field is preferably such that the magnetic flux is diverged outward from the center of the electrode. Then, the electrons drift along the diverging magnetic flux, and cations are attracted so as to cancel the electric field created by the electrons. As a result, the plasma is diffused.

As described above, from about 100 Torr to 7
In a pressure region of 60 Torr, addition of a dielectric substance and a rare gas on the electrode surface is necessary, but in a pressure region of about 100 Torr or less, a dielectric substance and a rare gas are not necessarily required.
However, the presence of a dielectric and a rare gas in a pressure region of about 100 Torr or less has an effect of stabilizing discharge and is effective. However, this is a factor that causes an increase in cost and a decrease in the deposition rate.

The inventor of the present invention has proposed a method of 5T
The physical properties of the plasma from rr to 760 Torr were observed. The gas used in the experiment was argon, and the electrode used was one into which a dielectric was inserted for plasma stabilization. As the dielectric, sintered alumina having a thickness of 0.5 mm was used. The high frequency is 13.56 MHz.

Typical physical properties of the plasma include an electron temperature (Te), an electron density (Ne), and a minimum voltage required to maintain the plasma (Sustaining Voltag).
e) was measured. Electron temperature (Te) and electron density (Ne)
Uses the Langmuir probe method (single probe method) to measure the minimum voltage (Sus
In the case of “taining voltage”, the terminal voltage of the power supply was measured. The results are shown in FIGS.

FIG. 9 shows the electron temperature (Te) and the electron density (N
e) is also shown. Electron density (Ne) is the probe voltage
Electrons that can be observed when applied to the positive voltage direction
The saturation current region is a pressure region where it cannot be observed (60 Torr).
Above), the calculation cannot be performed, and therefore 60T
Not shown above orr. Electricity below 40 Torr
The density of the particles (Ne) is 1 × 10 with increasing pressure.¹⁴/ M
^ThreeFrom 1.7 × 10¹⁴/ M^ThreeGradually rises to 40To
In the region from rr to 60 Torr, 8 × 10 ¹⁴/ M
^ThreeIt is rising. This is about 40 Torr
To indicate that arcing is occurring locally.
Of the area (40 Torr to 60 Torr)
It shows that Ma is becoming unstable. But,
By using this, you can obtain a very dense plasma
Can be.

FIG. 7 shows an electron temperature (Te) and a minimum voltage (Sustaining Vo) required to maintain plasma.
ltage) are also shown. Minimum voltage required to maintain plasma (Sustaining Voltag)
e) shows the ease of handling the plasma as an apparatus, irrespective of its physical meaning. Preferably, it is as low as possible. From this point of view, the minimum is shown between 10 Torr and 100 Torr, and it is preferable to use in this region.

On the other hand, the graph of the electron temperature (Te) is
Torr is minimized, and the shape is U-shaped. Fifteen
In the medium pressure region from Torr to 100 Torr, the electron temperature (T
e) is low and is 3 eV or less.

The above results are representative results only, and do not represent all. For example, changing the gas to helium, neon, adding hydrocarbon gas,
Varying the gas flow rate will give different results. For example, the pressure at which the electron temperature (Te) becomes a minimum is 60 Torr.
From 100 Torr to the electron density (Ne)
Pressure increases rapidly from 40 Torr to 80 Torr
And the pressure at which the minimum voltage (Sustaining Voltage) required to maintain the plasma is minimized varies from 20 Torr to 100 Torr. However, a qualitatively similar result is obtained.

From the above, it can be seen that the medium pressure range (15T
orr to 100 Torr), the minimum voltage required to sustain the plasma (Sustaining V)
It is preferable that the aging is low from the viewpoints of usability of the apparatus, weight reduction of the power supply and cost reduction, and increase of the electron density (Ne) is preferable from the viewpoint of increasing the radical density.

Further, in a medium pressure range (15 Torr to 10
At 0 Torr, the electron temperature is low, which is disadvantageous for the generation of radicals. However, since the plasma potential rises with respect to the anode which is the ground potential, ion bombardment to the anode occurs. I do. This is very convenient for producing a hard carbon film installed on the anode side. The reason will be described below.

The electrons and ions in the plasma move more easily under the same electric field strength due to the difference in their masses. Therefore, the probability that electrons reach the container is higher. If the container is an insulator, the container will be negatively charged. If the container is a conductor, assuming that the container in contact with the plasma has the same potential as the plasma, current flows in the direction of the plasma through the container. Since the flow of current is contrary to the neutral condition of charge, the potential of the plasma moves in a positive direction with respect to the container so as to cancel the flow of current.
That is, whether the container is a conductor or an insulator,
Due to the difference in mobility between electrons and ions, the plasma is positively charged with respect to the container.

This indicates that the ion sheath also exists on the ground electrode side. Of course, cathode (power supply electrode side)
Also has an ion sheath. However, naturally occurring ion sheaths are usually ignored because they are sufficiently smaller than sheaths generated by self-bias.

The electric field generated by the ion sheath can be estimated on the assumption that the ion sheath is equivalent to a capacitor using an electric double layer.

Assuming that the electron velocity has a Boltzmann distribution, the electron density in the ion sheath decreases exponentially, and the space charge in the ion sheath becomes an exponential curve. It is appropriate to define the boundary between the ion sheath and the plasma as a position where the potential becomes about Vt = −κ · Te / 2q with respect to the bulk potential of the plasma. This is because electrons in the plasma bulk are moving with an energy of about κ · Te / 2.

When the electron temperature (Te) increases, the electrons enter the ion sheath, so that the thickness d of the ion sheath decreases and the capacitance C of the electric double layer increases. Conversely, when the electron temperature (Te) decreases, the capacitance C of the electric double layer decreases. The amount of charge stored in the ion sheath is the electron density (N
e) That is, since it is proportional to the ion density (Ni), the voltage V applied to both ends of the electric double layer is as follows: V = Q / C = (Ne) ^2/3 · d / ε ₀ · S where d is an ion The thickness S of the sheath is the electrode area. That is, as the electron temperature (Te) is smaller, the electric field in the ion sheath becomes stronger, and the bombardment of ions to the anode becomes larger.

Conventionally, a hard carbon film could not be formed on the anode side.
From Torr to 100 Torr), as a result, the electron temperature was lowered, and ion bombardment was also generated on the anode, so that a hard carbon film could be formed on the anode side.

Further, according to the present invention, in opposition to the first electrode,
A second electrode having a grounded cylindrical shape, a film serving as a substrate on which a film is to be formed is wound around a part of the second electrode, and the second cylindrical electrode is rotated; Has a mechanism in which the film passes between the first and second electrodes, and applies a high-frequency electric field to the first electrode to convert the space between the first and second electrodes into a plasma. At least, in a film forming apparatus for forming a film by activating a source gas introduced into the plasma, a peripheral end of the first electrode is covered with an insulator, and the first electrode and the second electrode are covered with an insulator. A substantially closed space is formed by the electrode and the insulator, and gas is supplied to the closed space via a pore provided in the first electrode, and plasma is confined in the closed space and externally provided. Having a structure that is difficult to leak, and If the interval of the second electrode is at 6mm or less, and the pressure in the closed space from 15 Torr 1
A film forming apparatus characterized by being between 00 Torr.

This is because, in addition to the medium pressure, the plasma is confined in a closed space to prevent discharge in an undesired area, and further, a higher-density plasma is generated, and bombardment to the anode is performed. This is an increase in the number of employees.

The undesired region is specifically the periphery of the electrode. The electric field generally has a constant or uniform rate of change at the center of the electrode. However, the electric field intensity becomes large in the peripheral portion of the electrode, particularly in the end portion of the feeding electrode, and the discharge is concentrated in the region. That is, the impedance decreases due to an increase in the plasma density in the region, and a large amount of current flows in the region. Then, much of the power is consumed in the peripheral portion, and the plasma density in the central portion of the electrode decreases. This leads to an increase in electron density, and a reduction in ion bombardment at the center of the electrode.

Therefore, the above problem is solved by covering the peripheral end of the power supply electrode (first electrode) with an insulator and confining the plasma at the center.

Further, according to the present invention, in opposition to the first electrode,
A second electrode having a grounded cylindrical shape, a film serving as a substrate on which a film is to be formed is wound around a part of the second electrode, and the second cylindrical electrode is rotated; Has a mechanism that allows the film to pass between the first and second electrodes, and applies a high-frequency electric field to the first electrode to convert the space between the first and second electrodes into a plasma. At least, in a film forming apparatus for forming a film by activating the source gas introduced into the plasma, the electric field intensity formed by the first electrode with respect to the second electrode is higher than that of the first electrode. The electrode is configured to be strongest on the surface and weakest on the surface of the second electrode, and the shortest distance between the first electrode and the second electrode is 6 mm or less, and the first electrode The pressure between the electrode and the second electrode is 15 A film forming apparatus, characterized in that is between orr the 100 Torr.

This is because, in addition to the medium pressure, the first
The electric field intensity around the electrode, ie, the cathode, is increased, and the density of the plasma is increased in the region. As the shape of the first electrode, that is, the cathode electrode, in addition to the shape using the end of the flat plate, a knife shape or a needle shape is effective.

That is, high-density plasma is realized by positively utilizing the region where the electric field intensity is not uniform.

Further, according to the present invention, a first electrode to which a high-frequency electric field is applied and a grounded second electrode are disposed so as to face each other. A film forming apparatus for generating a plasma by activating a source gas introduced into the plasma to form a film, wherein a plasma is generated between the first and second electrodes on a grounded cylindrical metal surface. As the plasma is blown, the cylindrical metal is arranged, and a part of the cylindrical metal is wrapped with a film that is a substrate on which a coating is to be formed, and the cylindrical metal is rotated. In a film forming apparatus having a mechanism for passing the film through a plasma region, the distance between the first electrode and the second electrode is 6 mm or less, and the distance between the first electrode and the second electrode is Between the electrodes Forces from 15Torr 100
A film forming apparatus characterized by being between Torr.

This is a plasma generating apparatus having a parallel plate or concentric cylindrical electrode structure. Similarly, high-density plasma can be formed by applying a medium pressure. Things. Due to the medium pressure, gas diffusion is slower than at low pressure, and the transport of radicals may be rate-limiting. This was solved by spraying.

Further, according to the present invention, the gas supplied into the plasma space is a mixed gas of hydrogen and a gas selected from the group consisting of hydrocarbons, halogenated carbons and halogenated hydrocarbons, or The film forming apparatus according to claim 1, wherein the film forming apparatus is a mixed gas of a rare gas.

Although the film formation at a high speed can be realized by setting the medium pressure, on the other hand, adhesion of the film to the cathode poses a problem. This is solved by adding a carbon halide.

In the present invention, ion bombardment is applied to the anode side to form a hard carbon film on the anode side. However, a larger self-bias is applied to the cathode side than to the anode side. Bombardment is stronger than the anode side. In the present invention,
Utilizing this phenomenon, a halogen-based gas having an etching action is added to the source gas, and etching is performed on the cathode side instead of film formation.

A carbon halide, for example, carbon tetrafluoride, is known as an etching gas. Although only the etching effect can be seen with carbon tetrafluoride,
In the case of carbon or tricarbon octafluoride, etching or film formation is performed depending on the strength of self-bias.
That is, the film is etched when the self-bias is strong and the ion bombardment is strong, and the film is formed when the self-bias is weak and the ion bombardment is weak.

In the present invention, the bombardment is stronger on the cathode side where film formation is not preferable, which is very convenient. As a result, film formation on the cathode side can be suppressed,
The generation of flakes can be suppressed. Further, since the maintenance period of the apparatus can be extended, the throughput can be improved, which can greatly contribute to cost reduction.

In the case of an VLSI process or the like, contamination is likely to be avoided because it causes contamination. However, in the case of forming a carbon film as in the present invention, there is no need to worry about contamination.

Further, the present invention is the coating forming apparatus, wherein the base film is a conductive film. The present invention is most effective for a conductive film that can be placed only on the anode side, not on the cathode side.

The gist of the present invention is to form a hard carbon coating while ultrasonically oscillating a substrate. In particular, a magnetic recording medium is used as a substrate, and a hard carbon film is formed as a protective film of the magnetic recording medium.

In a plasma CVD apparatus having a parallel plate structure in which a high-frequency power source is connected to the electrode on which the substrate on which the hard carbon film is to be formed is arranged and the other electrode is a ground electrode, ultrasonic vibration is applied to the substrate. It is characterized by forming a carbon film while adding.

Further, the present invention is characterized in that a belt-like film substrate (for example, a tape-like film) is used as the substrate, and the substrate is run while applying ultrasonic vibration to form a hard carbon film on the surface thereof. .

Further, the present invention is characterized in that a film-like substrate is used as the substrate, and the substrate is vibrated in the direction between the electrodes, thereby realizing a biased state in the pulse mode or the high-frequency mode.

Further, the present invention relates to a method for forming a 1 mm ²
The number of pinholes per hit is 30 or less. The thickness of this hard carbon coating is 50 to 2000
{, Preferably 100 to 500}.

By including at least one element selected from the group consisting of Si, B, N, P and F in the hard carbon film used as the protective film in an amount of 20 atomic% or less, the adhesion of the film is improved. And has an effect to impart conductivity. For example, by including Si and P in the hard carbon film, the conductivity can be increased, and a protective film that is less likely to be charged with static electricity can be obtained.

When the substrate is subjected to ultrasonic vibration, cluster-like carbon or carbon molecules having small grains can be deposited on the surface of the substrate, and the carbon film to be formed can be made dense and uniform. This is because large carbon molecules are repelled from the vibrating substrate due to the ultrasonic vibration of the substrate, and molecules having a specific size or less are easily deposited on the surface of the substrate.

When an elongated film-shaped substrate such as a magnetic tape is used as the substrate, it is possible to prevent the substrate from being entangled by applying ultrasonic vibration to the substrate.

Further, particles (powder raw material which does not form a film) adhered to the surface of the substrate can be removed by ultrasonic vibration.

Further, by applying ultrasonic vibration in the direction between the electrodes arranged in parallel, a state in which an AC bias voltage is applied between the electrodes can be realized. This function is particularly effective when a film-like substrate such as a magnetic tape which is flexible and has a large amplitude is used.

The configuration for applying ultrasonic vibration to the base can be used for all the inventions disclosed in this specification.

[0074]

[Embodiment 1] An embodiment of the present invention will be described with reference to the drawings. In FIG. 4, supply roll 2 in vacuum vessel 1
The polymer substrate material 3 sent from the
And travels along the cylindrical can 7 in the direction of the arrow.

In this embodiment, a 4 cm wide and 6 μm thick polyimide film (generally used as a base of a magnetic tape) was used as the polymer substrate material 3.

The metal atoms evaporated from the evaporation source 6 are deposited on the polymer substrate material 3 to form a magnetic layer of 0.15 to 0.18 μm.
m.

In the present embodiment, Co-C
Using a r-Ni alloy, a pierce-type electron gun capable of scanning over a wide range, and applying an acceleration voltage of 35 KV, 5 × 10 ^-4 To
It was formed by electron beam evaporation at an operating pressure of rr. The passing speed of the polymer substrate material 3 was 135 m / min. The shielding plate 5 is provided to limit the deposition area.

A potential difference is applied between the cylindrical can 7 and the formed magnetic layer by the DC power supply 15 via the free roller guide 4. Here, a voltage of 80 V was applied so that the polymer substrate material 3 and the cylindrical can 7 were brought into close electrostatic contact. Polymer substrate material 3 with magnetic layer formed
Is guided to the vacuum vessel 9 via the intermediate roll 8 and subjected to plasma activation processing.

Here, the plasma activation process will be described. A source gas supply system 18 is provided between electrodes in which a ground electrode 10 and a high-frequency power supply electrode 11 are arranged in parallel at an interval of 3 cm.
The operating pressure was controlled to 10 ^-1 to 10 ^-2 Torr while introducing hydrogen gas and exhausting the gas through the exhaust system 19.
A high frequency of 0.5 Hz is applied from the high frequency power supply system 12 at a power density of 0.5 W / cm ² to form hydrogen plasma. The polymer substrate material 3 is configured to pass through the formed plasma region 16 at a speed synchronized with the magnetic layer forming step.

By performing this step, the surface of the magnetic layer is exposed to active hydrogen radicals or hydrogen ions. As a result, the surface of the magnetic layer is activated at the same time as being appropriately cleaned. The same effect can be obtained even when an argon gas or a mixed gas of argon and hydrogen is used. The size of the gap through which the polymer substrate material 3 opened in the wall separating the vacuum chamber 9 and the buffer chamber 20 should pass depends on the Debye distance of the plasma 16 generated in the vacuum vessel 2 or the pressure in the plasma region 16. It should be smaller than the mean free path. Then, the plasma does not leak into the buffer chamber 20.

Next, a description will be given of the vacuum container 13 which is a region for forming a coating containing carbon as a main component. The polymer substrate material 3 on which the magnetic layer guided through the free roller guide 4 is deposited, has a coating mainly composed of high-quality carbon as it passes through the region where the plurality of beam-type plasma generators are arranged. Is formed.

Here, a plasma generator for generating beam-type plasma will be described with reference to FIG. The plasma generating apparatus shown in FIG. 1 uses a gas mainly composed of a rare gas such as helium or argon, and exceeds 1 Torr and exceeds 200 Torr.
Medium pressure below Torr, preferably 5 to 150 Torr
r, more preferably at a pressure of 50-100 Torr. As the rare gas, at least one kind of gas selected from helium, argon, xenon, neon, and krypton can be used. Of course, these rare gases may be mixed and used.

However, if ignoring cost, helium is preferable because it has good discharge stability. Considering the cost, argon is advantageous in that it is cheaper, although the discharge stability is difficult. When argon is used, an insulator having a relative dielectric constant of 9 or more, for example, alumina is preferable.

In the present embodiment, the area of the plasma generated by one plasma generator shown in FIG.
As shown in FIG. 5, four plasma generators 52 are arranged alternately, so that a film mainly composed of carbon can be uniformly formed on the surface of the polymer substrate material 3 having a width of 20 mm as shown in FIG. There is.

The outline of the plasma generator shown in FIG. 1 will be described below. The plasma generator shown in FIG. 1 generates a plasma by generating a discharge between coaxial electrodes and emits the plasma in a beam form outside the apparatus. Discharge is performed by using a gas mainly composed of a rare gas. The formation of a film containing carbon as a main component is performed by adding a hydrocarbon gas as a raw material gas such as methane or alcohol to a rare gas. Further, as described later, a film can be formed by devising an electrode structure and separately supplying a raw material gas.

In the apparatus shown in FIG. 1, the discharge is carried out by a coaxial cylindrical electrode composed of a central conductor 31, a cylindrical insulator 33 and an outer conductor 29. Specifically, the center conductor 3
Discharge is performed in the gap between the first insulator 1 and the cylindrical insulator 33. In the present embodiment, no gas is supplied to the gap between the cylindrical insulator 33 and the outer conductor 29, so that discharge is not performed in this portion.

In this embodiment, the center conductor 31 is made of stainless steel,
The cylindrical insulator 33 is made of quartz glass, and the outer conductor 29 is made of stainless steel. It is desirable to use a material having a large dielectric constant as much as possible for the cylindrical insulator. It is also useful to provide irregularities or protrusions on the surface of the center conductor 31 to facilitate discharge.

The center conductor 31 is connected to the MHV coaxial connector 21, and an AC electric field is applied from the AC power supply 12 (see FIG. 4) via a coaxial cable connected to the MHV coaxial connector 21, so that the center conductor 31 and the external conductor 29 is supplied with electromagnetic energy. A gas mainly composed of a rare gas (for example, helium) supplied between the central conductor 31 and the cylindrical insulator 33 is supplied from the gas inlet 10 and passes between the Teflon insulators 22 and 27. Flow in. The Teflon insulators 22 and 27 also have a role of preventing discharge in unnecessary places. The housings 23 and 28 are fixed by fastening jigs 25 and 26. The housings 23 and 28 and the fastening jigs 25 and 26 are made of stainless steel, and are kept at the ground potential together with the outer conductor 29.

The ratio of the rare gas in the gas mainly composed of the rare gas is preferably 80% or more. This is because at a pressure of several Torr or more, the rare gas is mainly turned into plasma, and the source gas is activated by the energy of the plasma-converted rare gas, and the source gas (for example, methane) is hardly directly activated. is there. The unnecessary gas is exhausted from the exhaust system 19 (see FIG. 4).

The gas mainly composed of the introduced rare gas is sealed by an O-ring 24 so as not to leak from gaps between the components. The gap between the cylindrical insulator 33 and the outer conductor 29 is filled with a conductive metal foil. Therefore, no gas flows in the gap between the cylindrical insulator 33 and the outer conductor 29. Of course, gas may be flowed into this gap.

In this embodiment, the distance between the surface to be formed (polymer substrate material 3) and the center conductor 31 is 2 mm. The diameter of the central conductor 31 is 5 mm, the outer diameter of the cylindrical insulator 33 is 22 mm, and the thickness is 1 mm. The length of the electrode is 30 mm. When a gas of 90% helium is used as a rare gas, a plasma having a diameter of just over 20 mm is generated. That is, a plasma treatment can be performed on a region having a diameter of just over 20 mm.

FIG. 2 shows a cross section taken along the line AA ′ of FIG. FIG. 2 shows the center conductor 31, the outer conductor 29, and the cylindrical insulator 33. A mixed gas of a rare gas and a source gas (a gas mainly composed of a rare gas) passes through the gap 32 and is turned into plasma in the gap 32. Then, a beam-like plasma is injected to the outside of the apparatus, and a film is formed by the activated source gas.

In the structure shown in FIG. 4, since the width of the polymer substrate material 3 is 20 mm, as shown in FIG.
The four plasma generators (indicated by 52 in FIG. 5) shown in FIG. 5 are alternately arranged to form a uniform film. The four plasma generators 52 are arranged at a portion indicated by 41 in FIG.
A high frequency of 6 MHz is supplied at 500 W each. The plasma is generated in a region indicated by 51, and a film is formed in that region. In this embodiment, a film mainly containing carbon can be formed by using helium as a rare gas and methane as a source gas.

The film forming conditions are shown below. Input power 500W (per unit) Pressure 100Torr Gas Helium: methane = 100sccm: 10s
ccm (per unit)

The generated plasma is a low-temperature glow discharge at a temperature of 100 ° C. or less. Therefore, there is no problem even if the gas is a polymer substrate material, and good film formation can be performed.

Note that a DC or AC (high frequency) bias voltage may be applied to the surface to be formed by using the bias power supply 42 shown in FIG. Further, a magnetic field may be applied to the formation surface so that the beam-like plasma is effectively jetted to the formation surface.

The method of arranging the plasma generator as shown in FIG. 5 can be freely set depending on the required film forming speed and the size of the surface to be formed. For example, if another set as shown in FIG. 5 is provided, the film forming speed can be doubled.

The film containing carbon as a main component is formed at a passage speed interlocked with the above-described two steps.
A film having a thickness of 0 ° and containing carbon as a main component is formed. The polymer substrate material 3 on which the film formation has been completed is collected by the take-up roll 14 via the free roller guide 4.

In practicing the present invention, the treatment before the formation of the magnetic layer can be carried out by a known technique such as irradiation with ions and electrons or heating, if necessary. As the substrate, for example, a polyimide film is used in this embodiment, but a metal resin, plastic, or the like may be used in a roll shape or a plate shape.

The magnetic recording medium produced in this example was cut into a tape shape having a width of 8 mm, and the reproduction output and the durability were evaluated using a commercially available 8 mm video deck. When the thickness was 200 mm or more, stable reproduction output with little drop-up and excellent running stability and still durability was obtained.

It was also confirmed that excellent durability was exhibited in continuous and intermittent tests of special reproducing operations in addition to the normal reproducing operation.

[Embodiment 2] This embodiment is an example in which, in the configuration shown in Embodiment 1, a reaction product does not adhere to a coaxial discharge electrode portion. This embodiment differs from the configuration shown in the first embodiment in that the central conductor (center electrode 31) is hollow and the raw material gas flows through the hollow portion 30, as shown in FIG. FIG. 3 is a schematic view of a cross section taken along line AA ′ of FIG.

When such a configuration is adopted, the gap 32
, And a raw material gas (eg, methane) flows through the hollow portion 30. Hollow part 3
At 0, no discharge occurs, so that the source gas is not activated at all here and is discharged outside the apparatus. On the other hand, the rare gas flowing through the gap 32 is turned into plasma by high-frequency discharge performed between the center conductor 31 and the outer conductor 29. Then, the raw material gas which has not been activated at the place of leaving the apparatus is coaxially enveloped by the rare gas converted into plasma, and is activated or converted into plasma by the plasma energy of the rare gas.

Since the raw material gas is activated outside the apparatus, the possibility that reaction products adhere to the inside of the apparatus and generate flakes can be basically eliminated. Further, since the source gas is wrapped by the rare gas converted into plasma outside the apparatus, the collection efficiency can be extremely increased.

[Embodiment 3] This embodiment is an example in which the plasma generator disposed at the portion indicated by 41 in FIG. 4 is a sheet-like (plate-like) plasma generator. FIG. 6 shows the configuration of this sheet-shaped plasma generator.

The apparatus shown in FIG. 6 has parallel plate type electrodes, draws plasma generated by the parallel plate electrodes outside the apparatus as plate-like plasma, and uses this sheet-like plasma.

In FIG. 6, the parallel plate electrode portion includes an electrode plate 61, an insulator plate 63, and an outer casing 62.
The insulator plate 63 is provided in close contact with the outer casing 62. In this embodiment, the electrode plate 61 is made of stainless steel,
Reference numeral 3 denotes quartz glass, and the outer casing 62 uses stainless steel. The electrode plate 61 has three Teflon shields 620, 62
Insulated from others at 1, 622 and connected to the MHV coaxial plug 611. An AC electric field is applied to the electrode plate 61 from an AC power supply (13.56 NHz) 64 (corresponding to 42 in FIG. 4) via a coaxial cable (not shown) connected to the MHV coaxial connector 611. The rare gas supplied between the electrode plate 61 and the insulator plate 63 is supplied from the gas inlet 612,
The gas is supplied through a gas groove carved in a Teflon insulator 613. The Teflon insulator 613 also has a role of preventing discharge in unnecessary places. The outer case 62 and the electrode plate holder 616 are screw-fixed on the top plate 617. The electrode plate holder 616 and the top plate 617 are made of stainless steel,
It is kept at the ground potential together with the outer housing 62. The width of the opposing insulator plate, that is, the discharge portion width (the length in the depth direction of the electrode in FIG. 6) is 25 mm, and the thickness of the insulator is 1.0 mm. The electrode interval is 5 mm, and the electrode length (vertical length in FIG. 6) is 30 mm. Therefore, approximately 5 mm × 2
A 5 mm sheet-type plasma will be generated.

Helium was supplied at a flow rate of 100 sccm to the above apparatus, and a frequency of 13.56 MHz was applied at a pressure of 100 Torr.
When 500 W of the high-frequency power was applied, stable discharge was obtained over the entire width of the discharge portion, and sheet-like (plate-like) plasma could be released to the outside of the apparatus. Even if this state was maintained for more than 10 minutes, no trouble on the apparatus such as overheating occurred.

When the temperature of the plasma formed by the discharge was measured by blowing the plasma onto the thermocouple, it was found that the temperature was from room temperature to about 70 ° C. This confirms that low-temperature glow discharge is being performed.

In the case of using the structure shown in FIG. 4, a raw material gas such as methane or ethylene may be flowed as an additional gas.
In the case of increasing the deposition rate or increasing the deposition area, a plurality of devices may be arranged as shown in FIG.

[Embodiment 4] This embodiment is an example in which the part indicated by 41 in FIG. 4 is configured as shown in FIG. FIG.
In the above, 81 is a film-like substrate. Examples of such a film-like substrate include a tape of a magnetic storage medium. Reference numeral 82 denotes a cathode electrode, which is connected to a high-frequency power supply 87 via a matching box 86. Reference numeral 85 denotes a cylindrical electrode constituting the anode electrode, which is grounded. High-frequency discharge is performed in a plasma reaction space 89 between the anode electrode 85 and the cathode electrode 82. Further, the anode electrode 82 is configured to rotate and the film-shaped substrate 81 to move smoothly. 83 is an insulator. Reference numeral 84 denotes a gas introduction pipe, and the raw material gas, the dilution gas, and the additional gas are:
The gas is led to the plasma discharge space 89 through the gas introduction pipe 84. These gases are guided from the gas introduction pipe 84 to the pores 88 provided on the anode electrode 82 and are ejected into the plasma reaction space.

Width of cathode electrode 82 (width effective for discharge)
Is 20 mm and its length is 30 cm. The cylindrical anode electrode 85 has a diameter of 20 mm,
Its length is 30 cm. The distance between the cathode electrode 82 and the anode electrode 85 is 5 mm. The distance between the pair of electrodes is preferably 10 mm or less.

An example in which a 10-inch wide organic resin film on which a magnetic metal material is deposited is used as the film-like substrate 81 and a hard carbon film is formed to a thickness of 300 mm on the surface thereof will be described. Here, the film-like substrate is 12 m /
It is assumed that the robot is moved at a speed of 20 min / sec. In this case, the discharge space 89 having a width of 20 mm is filled with a film-shaped substrate having a width of 0.1 mm.
It will move in one second. Therefore, in order to form a film with a thickness of 300 °, the film forming speed is set to 3000 ° / sec.
Is required.

In the following, using the configuration shown in FIG.
The conditions for obtaining a film forming rate of 3000 ° / sec are shown below. Reaction pressure 60 Torr Input power 300 W (5 W / cm ² ) (13.56
MHz) Source gas C ₂ H ₄ : H ₂ : Ar = 1: 1: 2 (total 1000 sccm) Additive gas C ₂ F ₆ (10% added to C ₂ H ₄ )

By setting the above film forming conditions, 300
A film formation rate of 0 ° / sec can be obtained. And
A hard carbon film having a thickness of 300 mm can be formed on the surface of the film-like substrate 81.

The reason why C ₂ F ₆ was used as the additive gas is as follows. Generally, when a film is formed at a high film forming rate as described above, a large amount of reaction products adhere to the cathode electrode. This reaction product turns into flakes and hinders film formation. Therefore, it is necessary to take measures to prevent the reaction product from adhering to the cathode electrode.

On the other hand, when the configuration shown in FIG.
The cathode electrode 82 is biased to a negative potential by the action of the self-bias, and positive ions generated by the plasma discharge are attracted to the cathode electrode 82 side.
As a result, the cathode electrode 82 is sputtered.

Therefore, when C ₂ F ₆ is used as an additive gas as in this embodiment, the cathode electrode 82 is sputtered and etched. Therefore, the reaction product attached to the cathode electrode 82 is etched at the same time as the attachment. Thus, the hard carbon film can be formed without the reaction product adhering to the cathode electrode.

The reason why C ₂ F ₆ is used is that C ₂ F ₆
This is because there is an etching effect by F and a film forming effect of a hard carbon film by C. Here, CF ₄ can be used as an additive gas. However, CF ₄ does not have a film-forming effect on the hard carbon film, so it is preferable to use C ₂ F ₆ which contributes to the film formation of the hard carbon film.

As described above, by forming a film on the substrate on the side of the anode electrode 85 while etching the cathode electrode 82 with a halogen-based gas, the reaction products can be prevented from adhering to the cathode electrode 82. Film formation can be performed on the surface of the film-like substrate 81.

[Embodiment 5] FIG.
3 is a plasma CVD apparatus for forming a hard carbon film on the surface. The apparatus shown in FIG. 10 is characterized in that a film is formed while the substrate 113 is subjected to ultrasonic vibration. Hereinafter, the plasma CVD apparatus shown in FIG. 10 will be described. Further, as the base 113, a magnetic recording medium such as a magneto-optical disk is used.

The plasma CVD apparatus shown in FIG. 10 has a pair of electrodes 112 and 114 for activating (plasma) a reactive gas in a vacuum vessel 111. The electrode 114 is grounded, and the electrode 112 is
5 is connected. Here, a high-frequency power source 115 that generates a high frequency of 13.56 MHz is used. Although not shown in the figure, a gas introduction system, an exhaust system, and a matching device are arranged. If necessary, a heating means such as a heater or an infrared light lamp is provided.

On the electrode 112, a pair of electrodes 122 and 1
23, a piezoelectric element 121 is provided, and a base 113 is disposed thereon. The power supply 1 is connected to the piezoelectric element 121.
25 is applied to the piezoelectric element 1 at a predetermined frequency.
21 vibrates. This frequency is arbitrary, for example, 1
Frequencies from KHz to 100 MHz can be used.

It is necessary to insulate the electrode 123 from the electrode 112. Further, if necessary, the base 113 is mechanically fixed to the electrode 122 by a brazing material or an adhesive, and furthermore, a projection or a key-shaped locking member (a member for fixing the base).

As the piezoelectric element 121, quartz, roschel salt, lithium niobate, barium titanate, lead zirconate titanate (PZP), other organic piezoelectric substances, piezoelectric ceramics and the like can be used.

FIG. 12 is an enlarged schematic view of a portion of the piezoelectric element 121. As shown in FIG. FIG. 12 shows the piezoelectric element 1
21 and a pair of electrodes 12 for applying a voltage to the piezoelectric element
2 and 123, and a substrate 11 on which a hard carbon film is formed
3. High frequency power supply 1 for applying voltage to the piezoelectric element
25. The base 113 vibrates as the piezoelectric element 121 ultrasonically vibrates.

The vibration direction and frequency of the piezoelectric element 121 can be selected according to the cutting direction. The vibration direction can be selected from the thickness direction and the surface direction of the piezoelectric element 121, and the mode of the vibration can be a sliding vibration or a bending vibration. The control of the vibration output can be performed by monitoring the voltage applied to the piezoelectric element 121.

In the plasma CVD apparatus shown in FIG. 10, the distance between the pair of electrodes 112 and 114 is preferably made as small as possible. This is an experimental finding. Specifically, if the interval is 10 mm or less, a high film forming speed and good film quality can be obtained. However, when the configuration as shown in FIG. 10 is employed, since the electrode spacing is limited by the thickness of the piezoelectric element 121 and the thickness of the base 113, the value is preferably set to 20 mm or less.

The conditions for forming a hard carbon film on the substrate 113 will be described below. Here, an organic resin plate was used as the base 113 instead of the magneto-optical disk. Raw material gas Ethylene gas + hydrogen gas Operating pressure 80 Pa High frequency power 1.5 kW Base temperature Non-heating

The hard carbon film formed on the substrate 113 under the above conditions had a film thickness of 200 °, little peeling, and a dense film quality. In addition, the number of pinholes in the hard carbon coating was 10 / mm ² or less on average.

[Embodiment 6] The present embodiment relates to a structure for applying ultrasonic vibration to the base 113 by means different from that of the fifth embodiment. FIG. 13 shows an outline of the plasma CVD apparatus of this embodiment. The feature in FIG. 13 is that the electrode 112 is vibrated by the ultrasonic vibrator 141. With such a configuration, the base 113 can be ultrasonically vibrated. In addition, by adopting the configuration shown in FIG. 13, the distance between the pair of electrodes 112 and 114 is reduced by one.
0 mm or less, and high-speed film formation can be realized.

[Embodiment 7] This embodiment is an example in which a tape-like material such as a magnetic tape is coated with a hard carbon film. FIG. 14 shows an outline of a plasma CVD apparatus used in this embodiment. The plasma CVD apparatus shown in FIG. 14 includes a roll-shaped electrode 155, an electrode 156 paired with the roll-shaped electrode 155, guide rollers 153 and 154 also serving as an ultrasonic vibrator, and a roll-feeding electrode. Drum 151 or 152, and a winding drum 152 or 151 are provided. Although not shown, a gas introduction system such as a reactive gas, a doping gas, and a dilution gas, and a gas exhaust system are provided.

Here, a belt-like substrate of a polyimide film (substrate material of a magnetic tape) is used as the tape-like substrate. As shown in FIG.
57 is wound and moved from one drum 151 or 152 to the other drum 152 or 151. The drum-shaped electrode 155 is a 13.56 MHz high frequency power supply 11.
5 and is discharged between the electrode 156 which is a ground electrode. At this time, the drum-shaped electrode 155 also rotates as the base 157 moves. At this time, a hard carbon film is formed on the surface of the film-like substrate 157.

That is, as each drum and roller rotate, the film-like substrate moves from one drum to the other, and a hard carbon film is formed on the surface of the film-like substrate.

An example of actual film forming conditions is shown below. The moving speed of the substrate was 50 m / min. The thickness of the formed hard carbon film is 200 °.

The film quality of the formed hard carbon film was measured by Raman spectrum. As a result, the film showed characteristics as a diamond-like carbon film and was confirmed to be a good quality hard carbon film. Also, the number of pinholes was 30 / mm ² or less, and the chemical resistance and the blocking action against moisture were also good.

In the configuration shown in FIG. 14, the ultrasonic vibration is applied to the film-like base 157 from the guide rollers 153 and 154. In this case, the surface vibration is generated by the pair of guide rollers 153 and 154. Ultrasonic vibration can be applied to the film-like substrate 157.

In particular, by applying ultrasonic vibration to the base body 157 by the guide rollers 153 and 154, a tape-shaped thin film-like film is formed in a place other than the reaction space (space between the electrodes 155 and 156 where discharge is performed). The entanglement of the base 157 can be prevented. Further, the substrate 1
Particles adhered to the surface of the surface 57 can be removed, and productivity can be improved.

The substrate 157 on which the film formation has been completed is wound around the drum 151 or 152.

The method of applying ultrasonic waves to the film-like base 157 is not limited to the guide rollers 153 and 154, but may be a method in which an ultrasonic vibrator is separately brought into contact with the film-like base 157 to apply ultrasonic vibration. Good. The drum-shaped electrode 15 in contact with the film-shaped base 157
5 may be ultrasonically vibrated.

[Embodiment 8] This embodiment relates to a configuration in which the drum-shaped electrode 155 is vibrated in the apparatus shown in FIG. In order to ultrasonically vibrate the drum-shaped electrode 155, an ultrasonic vibrator may be disposed in close contact with the electrode 155.

The state of the vibration of the electrode 155 is shown in FIG.
5, the direction between the electrodes, that is, the substrate 15
A method of applying vibration in a direction perpendicular to the vertical direction (vertical direction in the drawing), and a direction perpendicular to the direction between the electrodes, that is, the base 157
There is a method in which vibration is applied in a direction parallel to (i.e., left and right in the drawing).

In FIG. 14, when the electrode 155 is ultrasonically vibrated up and down, a state where an AC bias is applied can be realized. As is well known, when the configuration as shown in FIG. 14 is employed, the electrode 155 connected to the high-frequency power supply is negatively charged with respect to the grounded electrode 156, and has a negative bias (called self-bias). Is applied.
In this state, if the electrode 155 vibrates up and down, the ions accelerated in the direction of the electrode 155 will cause the base 15
7 is accelerated in a certain period (determined by the frequency of the ultrasonic vibration applied to the electrode 155), and a state of approaching or moving away is realized. That is, a state in which an AC bias is applied to the electrode 155 is realized.

The above operation is performed by the guide rollers 153, 1
Although it can be obtained even when ultrasonic vibration is applied to 54, it is more remarkable when ultrasonic vibration is applied to the electrode 155. Further, in a state as shown in FIG. 5, when a supersonic vibration is applied to a flexible base (for example, a base such as a magnetic tape), the effect can be more remarkably obtained.

[Embodiment 9] This embodiment shows an example in which a surface protective film of a magneto-optical disk as a magnetic recording medium is formed using the apparatus shown in FIG. 10 or FIG. A magneto-optical disk or an optical disk memory is widely known as a recording medium as represented by a CD (compact disk). These discs are made of an organic resin or an industrial plastic material, and have characteristics such as high productivity and easy handling.

However, a protective film for protecting the surface layer is required. This protective film needs to transmit light in the visible light region (a semiconductor laser light of 700 to 800 nm is generally used), and is required to have high hardness and adhesion.

It is conceivable to use a hard carbon film formed by the apparatus shown in FIGS. 10 and 14 as a protective film satisfying such requirements. As the film forming method, the base 11
An optical disk may be used as 3. Since the hard carbon film can be formed without heating, it is most suitable as a surface protection film of an optical disk using a material weak to heat.

In the above embodiment, an example is shown in which a frequency of 13.56 MHz is used as a high frequency for causing discharge. However, the present invention is not limited to this frequency. Further, pulse discharge may be used. Further, a DC or AC bias may be applied in addition to the high frequency discharge.

As a raw material gas for the hard carbon film, a hydrocarbon gas such as methane, alcohol, or the like can be used. Further, at the time of film formation, hydrogen, another additive gas, or a doping gas can be introduced.

[Embodiment 10] An outline of this embodiment is shown in FIG. The apparatus shown in FIG. 8 is an apparatus for forming a coating on the surface of a tape or film-like substrate. In this embodiment, a configuration in which a carbon coating is formed as a surface protective film on the surface of a magnetic tape will be described. In the configuration shown in FIG.
Reference numeral 81 denotes a film-like substrate, in which a magnetic material is formed on a surface of a resin material such as polyimide by a vapor deposition method or the like. Reference numeral 82 denotes a cathode electrode, which is connected to a high-frequency power supply 87 via a matching box 86. Reference numeral 85 denotes a can roll constituting the anode electrode, which rotates during film formation to transfer the substrate 81. The electrode 85 is configured to vibrate ultrasonically by a piezoelectric element. In other words, during the film formation, the substrate 81 is subjected to ultrasonic vibration by the cylindrical electrode 85, so that the substrate 81 is ultrasonically vibrated.

In the film formation, high-frequency discharge is performed in a plasma reaction space 89 between the anode electrode 85 and the cathode electrode. 83 is an insulator, and 84 is a gas introduction pipe. From the gas introduction pipe, diluent gases such as methane and hydrogen, which are source gases, are introduced into the plasma reaction space 89. The gas is supplied to pores 88 provided in the anode electrode 82.
From the reaction space 89.

The width of the cathode electrode is, for example, 20 mm. The length is, for example, 30 cm. The diameter of the cylindrical anode electrode 801 is, for example, 20 mm. The length is, for example, 30 cm. In such a case, a substrate having a width of 30 cm or less can be used as the base 81. Examples of film forming conditions when the electrodes having the above dimensions are used are shown below. Reaction pressure 60 Torr Input power 300 W (13.56 MHz) Raw material gas C ₂ H ₄ : H ₂ : Ar = 1: 1: 2
(Total 1000 sccm) Additional gas C ₂ F ₆ (10% added to C ₂ H ₄ ) Ultrasonic frequency 30 KHz (ultrasonic vibration applied to electrode 801) Ultrasonic vibration applied to base 81 via electrode 85 This makes it possible to form a dense pinhole-free carbon coating without the reaction product flakes adhering to the formation surface of the base 81.

[0153]

According to the present invention, it is possible to provide an apparatus capable of stably and reliably producing a hard carbon film on the surface of a magnetic recording medium having a conductive metal magnetic layer.

In the prior art, a sufficiently hard carbon film could not be formed on the ground electrode side. However, the present invention provides sufficient wear resistance and lubrication even when the carbon film is in contact with the anode which is the ground electrode. An apparatus capable of forming a carbon film having properties can be provided.

Further, according to the present invention, it is possible to provide an apparatus capable of forming a hard carbon film as a protective film at the same time as the magnetic layer forming process.

Further, according to the present invention, it is possible to provide an apparatus capable of suppressing generation of flakes due to contamination of an electrode, which is a new problem caused by achieving high-speed film formation. Thereby, film formation on the cathode side can be suppressed, and generation of flakes can be suppressed. Further, since the maintenance period of the apparatus can be extended, the throughput can be improved, which can greatly contribute to cost reduction.

Further, the magnetic recording medium manufactured by the manufacturing apparatus of the present invention can be improved in interface characteristics and adhesion between the magnetic layer and the film containing carbon as a main component, and can be of high quality. Furthermore, lower oxides generated on the surface of the magnetic layer cannot be removed essentially by simply avoiding exposure to the atmosphere,
The plasma activation processing according to the present invention is effective.

Further, the surface characteristics of the coating containing carbon as a main component, that is, the abrasion resistance, the high smoothness, the hardness and the like are remarkably improved, and it is possible to manufacture a magnetic recording medium of industrially sufficient value. The problematic rule point in continuous formation can also be avoided.

By forming the hard carbon film while applying ultrasonic vibration to the substrate, a dense and good film quality can be obtained. In particular, a very dense carbon coating having the number of pinholes of 30 / mm ² or less can be obtained, which is extremely useful as a protective film.

[Brief description of the drawings]

FIG. 1 shows a schematic cross section of a plasma generator.

FIG. 2 shows a cross section taken along the line A-A 'in FIG.

FIG. 3 is a cross-sectional view taken along line A-A 'of FIG.

FIG. 4 shows an outline of a film forming apparatus of an embodiment.

FIG. 5 shows an arrangement state of a plasma generator.

FIG. 6 shows a schematic sectional view of a plasma generator.

FIG. 7 shows the pressure and electron temperature (Te), and the minimum voltage (Sustainin) required to maintain pressure and plasma.
g Voltage).

FIG. 8 shows a schematic cross section of a plasma generator.

FIG. 9 shows the relationship between pressure and electron temperature (Te), and the relationship between pressure and electron density (Ne).

FIG. 10 shows a configuration of an example.

FIG. 11 shows a configuration of a conventional example.

FIG. 12 shows a configuration of an example.

FIG. 13 shows a configuration of an example.

FIG. 14 shows a configuration of an example.

[Brief description of reference numerals] [Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Supply roll 3 ... Polymer substrate material 4 ... Free roller guide 5 ... Shield plate 6 ... Evaporation source 7 ... Cylindrical can 8 ... Intermediate roll 9 Vacuum container (2) 10 Ground electrode 11 High-frequency power supply electrode 12 High-frequency power supply system 13 Vacuum container 14 Winding roll 15 DC power supply 16 Plasma area 17・ ・ Sheet beam type plasma region 18 ・ ・ Raw material supply system 19 ・ ・ Exhaust system 20 ・ ・ Buffer room 21 ・ ・ MHV connector 31 ・ ・ Center conductor 33 ・ ・ Cylinder insulator 29 ・ ・ Outer conductor 30 ・ ・Gas inlet 22 Teflon insulator 27 Teflon insulator 23 Casing 28 Casing 25 Jig 26 Jig 52 Plasma generator 42 Bias power supply 61・ Electrode plate 63 ... Edge plate 62 Outer housing 81 Film-shaped base 82 Cathode electrode 83 Insulator 84 Gas introduction tube 85 Anode electrode 86 Matching box 87 High frequency power supply 88 Pore 89 Plasma discharge space 620 Teflon shield 621 Teflon shield 622 Teflon shield 611 MHV connector 612 Gas inlet 616 Holder 617 Top plate 613 Teflon insulator 111 Vacuum container 112 ... electrode 113 ... substrate 114 ... electrode 115 ... high frequency power supply 121 ... piezoelectric element 122 ... electrode 123 ... electrode 125 ... high frequency Power supply 141 ··· Ultrasonic vibrator 151 ··· Sending drum / winding drum 152 ··· Winding drum / feeding Drum 153 ... guide roller 154 ... guide roller 155 .... drum shaped electrode 156 ... ground electrode 157 .... film-shaped base.

Claims (9)

[Claims] 1. A method for forming a film, comprising: plasma-activating a surface of a magnetic material to form a carbon film on the surface of the magnetic material. 2. A method for forming a film, comprising: after exposing a surface of a magnetic material to plasma, forming a carbon film on the surface of the magnetic material. 3. The method according to claim 2, wherein the plasma is a plasma of a hydrogen gas, an argon gas, or a mixed gas of hydrogen and argon. 4. The method according to claim 1, wherein
The method according to claim 1, wherein the magnetic material is a metal magnetic material. 5. The method according to claim 1, wherein:
The method according to claim 1, wherein the magnetic material is a Co-Cr-Ni alloy. 6. The method according to claim 1, wherein:
A method of forming a carbon film, comprising generating plasma of methane or alcohol as a raw material gas to form the carbon film. 7. The method according to claim 1, wherein
The method of forming a film, wherein the thickness of the carbon film is 50 to 2000 mm. 8. The method according to claim 1, wherein
A method of forming a film, wherein the carbon film is specified using a Raman spectrum. 9. The method according to claim 1, wherein:
The method for forming a film, wherein the carbon film is diamond-like carbon.