JPH07228965A - Film forming device - Google Patents

Abstract

PURPOSE:To form a carbon film which is smooth and has excellent wear resistance on the surfaces of a magnetic recording medium having a magnetic metallic layer by activating the surface of this medium, then passing the recording medium through the plasma formed by an atmosphere mixture composed of a rare gas and gaseous hydrocarbon. CONSTITUTION:A film 3 consisting of a high polymer material is transported along the outer periphery of a cylindrical can 7 in a vacuum vessel 1 and the vapor of, for example, Co-Cr-Ni alloy is generated from an evaporating source 6 and is deposited by evaporation as the magnetic film on the surface of the film 3. The film 3 having the magnetic film of the Co-Cr-Ni alloy is introduced into a vacuum vessel 9 where the film is passed between a grounding electrode 10 and a high-frequency supply electrode 11 consisting of a high-frequency power source 12. Gaseous H2 from a supply system 18 is introduced into this vessel to generate hydrogen plasma between both electrodes 10 and 11. The film 3 is passed in this plasma region 16, by which the surface is cleaned and activated. In succession, the film is introduced into a vacuum vessel 13, into which the rare gas such as Ar, and the gaseous hydrocarbon such as methane, are supplied. The film is passed between the electrodes 11 and 41 and the hard carbon film is formed on the surface of the alloy magnetic film.

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

Further, a technique of forming a coating 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 provide surface protection, wear resistance or lubricity. It has been known. This carbon-based coating film is usually formed by a CVD method typified by a plasma CVD method.

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

When a parallel plate type plasma CVD method is used to form a film containing carbon as a main component, the organic resin substrate which is the base of the magnetic storage medium must be installed on the cathode electrode side. Since a magnetic recording medium for high-density recording is generally obtained by vapor-depositing a metal magnetic material, when such a substrate is brought into contact with the cathode electrode, the substrate becomes a part of the electrode and a high frequency electric field leaks, which is not preferable. Discharge occurs in the area. Such an electric discharge has a high possibility of damaging the organic resin film which is a substrate, and has a problem in terms of production stability and reliability.

If a hard carbon film as a protective film is to be formed at the same time as the roll-to-roll type magnetic layer forming process, the film forming speed of the carbon film is slow, which is impossible.

[0007]

The main object of the present invention is to:
An object of the present invention is 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 a device capable of forming a carbon film having sufficient wear resistance and lubricity in a state of being in contact with an anode which is a ground electrode.

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

Further, it is an object of the present invention to provide an apparatus which can suppress the generation of flakes due to electrode contamination, which is a new problem caused by achieving high speed film formation.

[0011]

According to the present invention, a first electrode to which a high-frequency electric field is applied and a grounded second electrode are arranged so as to face each other, and the first and the second electrodes are applied by applying the high-frequency electric field. In a film forming apparatus for generating plasma between two electrodes and activating a raw material gas introduced into the plasma to form a film, a distance between the first electrode and the second electrode is 6 m.
m or less and the pressure between the electrodes is 15 Torr
To 100 Torr.

According to the present invention, the distance between the first and second electrodes is 6 mm or less, and the pressure is 15 Torr to 100 T.
The point is that a carbon film having a high hardness can be formed even if the substrate is in contact with the second electrode, which is the ground electrode, if it is between orr, and is based on the experimental findings of the inventor. Is.

Prior to the above findings, the present inventor generally
Pressure range selected by plasma CVD (10 mTorr
To 1 Torr) much higher pressure range (5 Torr
To 760 Torr), the physical properties of the plasma were observed. The reason why the pressure range higher than that which is generally considered is focused on because it is intended to improve the film formation rate of ordinary plasma CVD by an order of magnitude.

Considering the film formation process in plasma CVD (generation of radicals, transport to the substrate surface, reaction on the surface), (1) improvement of the density of radicals serving as a precursor for film formation (2) radicals It can be understood that the film forming rate can be improved if the two points of improving the transportation efficiency 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 the generation of radicals has a greater effect on the film formation rate than the transport of radicals. It can be expected that the radical density can be increased by increasing the reaction pressure. That is,
High-speed film formation can be expected in the high pressure region.

In the film forming process, (3) reaction on the film surface (suppression of surface desorption) can be considered, but in the case of a low temperature process such as plasma CVD, the surface reaction is not 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 hard carbon film, the bombardment of ions is positively acted during the film formation, the strong bond in the film is left and the weak bond is cut while the film is formed. Therefore, generally, the substrate is placed on the cathode side and the film is formed by using the self-bias.

Even if the increase in radical density is realized by increasing the pressure during film formation, it is meaningless that the plasma, which is a prerequisite for radical generation, changes its physical properties significantly due to the increase in pressure. Therefore, the present inventor observed the plasma in the high pressure region (5 Torr to 760 Torr) as described above.

First, the high pressure region (5 Torr to 76
This is a requirement for generating plasma at 0 Torr). Conventionally, low pressure glow discharge is from 10mTorr to 1T
The reason why the discharge is generated in the pressure region of orr is that the discharge is most likely to be 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 normal low-pressure glow) collide with electrons (electrons are accelerated by the electric field between the electrodes and (It is assumed to fly in the direction of one electrode) is proportional to the pressure of the atmosphere (inversely proportional to the mean free path). That is, if the pressure is low and the number of collisions is small, the electrons have sufficient energy,
If the particles collide, the particles are ionized, but due to the low pressure, the particles themselves are few and cannot be plasma. On the other hand, when the pressure is high, the number of collisions of electrons increases, the electrons do not have sufficient energy until the next collision, and the particles cannot be ionized even if they collide. This is known as Paschen's law. The discharge start voltage V becomes a function of the product (pd product) of the pressure p and the electrode interval d, and the minimum discharge start voltage Vmin exists at a certain pd product value. Is to do.

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

However, the effect of increasing the voltage applied between the electrodes is limited. That is, in the case of glow discharge, the electric field distribution in the plasma is not uniform, and the electric field is applied most to the sheath portion formed near the electrodes. Next, the positive column part following the sheath part is covered. The length of the sheath portion is about the Debye length peculiar to plasma, and the electric field is not so much applied to the positive column, which occupies most of the space spatially. Therefore, even if a large voltage is applied between the electrodes, a substantial increase in the electric field cannot be expected in the positive column portion that occupies most of the space. However, since the increased amount of the inter-electrode voltage is applied to the sheath portion, the ionization in this region is promoted. When the electric field applied to the sheath portion exceeds the limit, accelerated electrons collide with the surface of the electrode, and thermionic emission from the electrode occurs by heating the electrode. The mechanism of electron emission from the electrode in the case of glow discharge is field emission and secondary electron emission, but when thermionic emission occurs, the electric field consumed for electron emission from the electrode almost disappears, and the electric field corresponding to that is generated in the sheath portion. Will come to rest. Then, the electrons in the sheath portion are further accelerated to heat the electrode, causing thermal runaway as long as the electrode potential is maintained. Such a state is a negative resistance and transitions to arc discharge when a current flows over the entire path.

Therefore, for plasma generation in a high pressure region, it is effective to reduce the electrode interval. However, there is also a lower limit for the electrode spacing. In order for the plasma to be present, the electrode spacing must be at least several times the Debye distance. The Debye distance λ is expressed by the following equation. λ = (ε ₀ · κ · Te / q ² · Ne) ^1/2 where ε ₀ is the permittivity of vacuum κ is the Boltzmann constant q is the elementary charge of electricity 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 be 1 mm or more.

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

A heat-resistant dielectric is inserted on 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 entire system has a positive resistance. In this case, since the dielectric substance enters in 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 / recombination of ions and electrons in the space is increased, and the plasma is easily extinguished. Therefore, it is necessary to promote diffusion of ions and electrons (in particular, diffusion of ions) to broaden the plasma. Therefore, the addition of a rare gas having a metastable state, particularly helium or argon, is effective. The rare gas is preferably 80% or more of the total gas.

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

The present inventor uses the above-mentioned means to obtain a 5T
The physical properties of the plasma from orr to 760 Torr were observed. The gas used in the experiment was argon, and the electrode used was one with a dielectric inserted for plasma stabilization. The dielectric used was 0.5 mm thick sintered alumina. The frequency of the high frequency is 13.56 MHz.

As typical physical property values of plasma, electron temperature (Te), electron density (Ne), and minimum voltage (Sustaining Voltag) required to maintain plasma
e) was measured. Electron temperature (Te) and electron density (Ne)
Uses the Langmuir probe method (single probe method) to determine the minimum voltage (Sus
tainging voltage) measured the terminal voltage of the power supply. The results are shown in FIGS. 7 and 9.

FIG. 9 shows the electron temperature (Te) and the electron density (N
e) is shown at the same time. The electron density (Ne) is a pressure region (60 Torr) where the electron saturation current region, which can be observed when the probe voltage is applied in the positive voltage direction, cannot be observed.
Since the above exists, calculation cannot be performed, and therefore 60T
Orr and above are not shown. The electron density (Ne) below 40 Torr is 1 × 10 ¹⁴ / m with increasing pressure.
³ to 1.7 × 10 ¹⁴ / m ³ and gradually increased to 40 To
In the region from rr to 60 Torr, 8 × 10 ¹⁴ / m
^It has risen to ³ . This indicates that arc discharge is locally generated at a boundary of about 40 Torr, and plasma in this region (40 Torr to 60 Torr) is becoming unstable. But,
By utilizing this, a very high density plasma can be obtained.

FIG. 7 shows the minimum voltage (Sustaining Vo) required to maintain the electron temperature (Te) and plasma.
Figure 1) is shown at the same time. The minimum voltage required to maintain the plasma (Sustaining Voltag
e) is an object that indicates the ease of handling plasma as an apparatus, regardless of its physical meaning. It is preferably as low as possible. From this point of view, it exhibits a minimum between 10 Torr and 100 Torr, and it is preferably used in this region.

On the other hand, the graph of electron temperature (Te) is 60
Torr is minimized to form a U-shape. 15
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 only representative results and do not represent all of them. For example, changing the gas to helium, neon, etc., adding hydrocarbon gas,
If the gas flow rate is changed, the result will be different. For example, the pressure at which the electron temperature (Te) becomes minimum is 60 Torr.
To 100 Torr, electron density (Ne)
Is 40 Torr to 80 Torr
The pressure at which the minimum voltage (Sustaining Voltage) required to maintain the plasma is minimized changes in the range of 20 Torr to 100 Torr. However, qualitatively similar results are obtained.

From the above, the medium pressure region (15T
In the range from orr to 100 Torr), the minimum voltage (Sustaining V
It is preferable that the (age) is low in terms of usability of the device, weight saving of the power source and cost reduction, and increase of the electron density (Ne) is preferable in terms of the effect of increasing the radical density.

Furthermore, the medium pressure region (15 Torr to 10
In the range of 0 Torr), the electron temperature becomes low, which is disadvantageous for radical generation, but the plasma potential rises with respect to the anode, which is the ground potential, so that bombardment of ions to the anode occurs. To 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 than the difference in mass. Therefore, the electron has a higher probability of reaching the container. 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, a current flows in the direction of the plasma through the container. Since a current flows and the charge neutral condition is violated, the electric potential of the plasma moves in a positive direction with respect to the container so as to cancel the flow of the current.
That is, whether the container is a conductor or an insulator,
The plasma is positively charged to the container due to the difference in electron and ion mobilities.

This indicates that the ion sheath also exists on the ground electrode side. Of course, cathode (feeding electrode side)
Also has an ion sheath. However, normally, the naturally occurring ion sheath is sufficiently smaller than the self-biased sheath and is therefore ignored.

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

Assuming that the velocity of electrons 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 at which the potential becomes about Vt = −κ · Te / 2q with respect to the bulk potential of the plasma. This is because the electrons in the plasma bulk are moving at an energy of about κ · Te / 2.

When the electron temperature (Te) increases, electrons penetrate into 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 accumulated in the ion sheath is the electron density (N
e) That is, since it is proportional to the ion density (Ni), the voltage V across the electric double layer is 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, the smaller the electron temperature (Te), the stronger the electric field in the ion sheath, and the larger the bombardment of ions to the anode.

Conventionally, a hard carbon film could not be formed on the anode side, but in the apparatus of the present invention, the pressure is set to an intermediate pressure (15
From Torr to 100 Torr), the electron temperature was lowered as a result, and ion bombardment was also generated in the anode, so that a hard carbon film could be formed on the anode side as well.

Further, according to the present invention, facing the first electrode,
A cylindrical second electrode that is grounded, a film that is a substrate on which a film is to be formed is wound around a part of the second electrode, and the second cylindrical electrode rotates. Has a mechanism for allowing the film to pass between the first and second electrodes, and applies a high-frequency electric field to the first electrode to plasmaize the space between the first and second electrodes. At least, in a film forming apparatus for activating a raw material gas introduced into the plasma to form a film, a peripheral end portion of the first electrode is covered with an insulator, and the first electrode and the second electrode are formed. The electrode and the insulator substantially form a closed space, gas is supplied to the closed space through the pores provided in the first electrode, and plasma is confined in the closed space to the outside. It has a structure that prevents leakage, and If the interval of the second electrode is at 6mm or less, and the pressure in the closed space from 15 Torr 1
It is 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 region, and further, a higher density plasma is generated, thereby bombarding the anode. This is the realization of an increase in

Further, in the present invention, facing the first electrode,
A cylindrical second electrode that is grounded, a film that is a substrate on which a film is to be formed is wound around a part of the second electrode, and the second cylindrical electrode rotates. Has a mechanism for allowing the film to pass between the first and second electrodes, and applies a high frequency electric field to the first electrode to plasmaize the space between the first and second electrodes. At least, in the film forming apparatus which activates the raw material gas introduced into the plasma to form a film, the electric field strength formed by the first electrode with respect to the second electrode is equal to that of the first electrode. The electrodes are 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 is The pressure between the electrode and the second electrode is 15 A film forming apparatus, characterized in that is between orr the 100 Torr.

In addition to the medium pressure, the first
The electric field strength around the electrode (i.e., the cathode) is increased, and the plasma density is increased in this region. As the shape of the first electrode, that is, the cathode electrode, a knife-shaped or needle-shaped one is effective in addition to the one using the end portion of the flat plate.

Further, according to the present invention, the first electrode to which the high frequency electric field is applied and the grounded second electrode are arranged so as to face each other, and by applying the high frequency electric field, the first electrode and the second electrode are separated from each other. Is a plasma-generating apparatus, which activates a raw material gas introduced into the plasma to form a coating film, which is generated between the first and second electrodes on a grounded cylindrical metal surface. So that the plasma is blown, the cylindrical metal is arranged, a film that is a substrate on which a coating is to be formed is wound around a part of the cylindrical metal, and the cylindrical metal rotates, In a film forming apparatus having a mechanism of passing a plasma region where the film is blown, a distance between the first electrode and the second electrode is 6 mm or less, and the first electrode and the second electrode are Between the electrodes Forces from 15Torr 100
A film forming apparatus characterized by being between Torr.

This is a plasma generator having a parallel plate or concentric cylindrical electrode structure. Similarly, a high density plasma can be formed by applying an intermediate pressure, but this is positively blown to the substrate by a gas flow. It is a thing. Due to the medium pressure, the diffusion of gas is slower than that at low pressure, and the transport of radicals may be rate limiting. This is solved by spraying.

Further, in 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 mixed gas. The film forming apparatus according to each claim, wherein the film forming apparatus is a mixed gas of a rare gas.

By using an intermediate pressure, high speed film formation can be realized, but on the other hand, adhesion of the film to the cathode becomes a problem. This is solved by adding a carbon halide.

In the present invention, ion bombardment acts on the anode side to form a hard carbon film on the anode side as well, but since a larger self-bias is applied to the cathode side than to the anode side, the ionic bombardment is performed. The bombardment is stronger than on the anode side. In the present invention,
By utilizing this phenomenon, a halogen-based gas having an etching action is added to the raw material gas, and etching is performed on the cathode side instead of film formation.

Carbon halides such as carbon tetrafluoride are known as etching gases. Only carbon tetrafluoride has an etching effect, but hexafluorofluoride 2
Carbon or trifluorooctacarbonate may be etched or deposited depending on the strength of self-bias.
That is, when the self-bias is strong and the ion bombardment is strong, etching is performed, and when the self-bias is weak and the ion bombardment is weak, a film is formed.

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

Further, in the case of the VLSI process or the like, it is likely to be avoided because it causes contamination, but in the case of forming the carbon film as in the present invention, it is not necessary to care about the contamination.

Further, the present invention is the film forming apparatus, wherein the film that is the substrate is a conductive film. The present invention is most effective in the case of a conductive film that can be placed only on the anode side, not the cathode side.

[0052]

The present invention will be described in more detail with reference to the following examples. In the examples, the examples in which the present invention is carried out at the same time when the metal magnetic layer is formed are shown, and the examples in which the present invention works most effectively are shown.

[Embodiment 1] An embodiment of the present invention will be described with reference to the drawings. In FIG. 4, the polymer substrate material 3 fed from the supply roll 2 in the vacuum container 1 travels in the direction of the arrow along the cylindrical can 7 via the free roller guide 4.

In this example, a polyimide film having a width of 4 cm and a thickness of 6 μm 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.
It is formed to a film thickness of m.

In this example, Co--C was used as the evaporation material.
A Pierce-type electron gun capable of scanning a wide range is used with r-Ni alloy, acceleration voltage is 35 KV, and 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 shield 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 source 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 electrostatically brought into close contact with each other. Polymer substrate material 3 with magnetic layer formed
Is guided to the vacuum container 9 via the intermediate roll 8 and plasma activated.

Here, the plasma activation processing step will be described. The source gas supply system 18 is provided between the electrodes in which the ground electrode 10 and the high frequency power supply electrode 11 are arranged in parallel at an interval of 3 cm.
More hydrogen gas is introduced, and while being exhausted by the exhaust system 19, the operating pressure is controlled to 10 ^-1 to 10 ^-2 Torr and 13.56M.
A high frequency of 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 while being properly 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 be determined by the Debye distance of the plasma 16 generated in the vacuum chamber 2 or the pressure of the plasma region 16. It should be smaller than the mean free path. Then, the plasma will not leak into the buffer chamber 20.

Next, the vacuum container 13 which is a region for forming a film containing carbon as a main component will be described. On the polymer substrate material 3 on which the magnetic layer, which is guided through the free roller guide 4, is deposited, a film containing good-quality carbon as a main component in the process of passing through a region where a 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 generator shown in FIG. 1 uses a gas containing a rare gas such as helium or argon as a main component, and exceeds 200 Torr to 200 Torr.
Medium pressure, less than Torr, preferably 5 to 150 Torr
The plasma can be generated at a pressure of r, more preferably 50 to 100 Torr. At least one gas selected from helium, argon, xenon, neon, and krypton can be used as the rare gas. Of course, these rare gases may be mixed and used.

In this embodiment, the area of plasma generated by one plasma generator shown in FIG. 1 is 20 mm.
Since it is a strong φ, as shown in FIG. 5, four plasma generators 52 are arranged in a staggered manner so that a coating film containing carbon as a main component can be uniformly formed on the surface of the polymer substrate material 3 having a width of 20 mm. There is.

The outline of the plasma generator shown in FIG. 1 will be described below. In the plasma generator shown in FIG. 1, a discharge is generated between electrodes arranged coaxially to generate plasma, and the plasma is ejected in a beam shape outside the apparatus. The discharge is performed by using a gas mainly containing a rare gas. The film containing carbon as a main component is formed by adding a hydrocarbon gas as a raw material gas such as methane or alcohol to the rare gas. Further, the film can be formed by devising the electrode structure and supplying the source gas separately as described later.

In the device shown in FIG. 1, the discharge is performed by the coaxial cylindrical electrode composed of the central conductor 31, the cylindrical insulator 33 and the outer conductor 29. Specifically, the central conductor 3
Discharge is performed in the gap between the 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 central conductor 31 is stainless steel,
The cylindrical insulator 33 is made of quartz glass, and the outer conductor 29 is made of stainless steel. As the cylindrical insulator, it is desirable to use a material having a high dielectric constant as much as possible. Further, it is useful to provide unevenness or protrusions on the surface of the central 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 source 12 (see FIG. 4) via the coaxial cable connected to the MHV coaxial connector 21, so that the center conductor 31 and the outer conductor are connected. Electromagnetic energy is supplied to and from 29. A gas containing a rare gas (for example, helium) as a main component, which is 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. Pour in. The Teflon insulators 22 and 27 also have a role of preventing discharge in unnecessary places. The casings 23 and 28 are fixed by tightening jigs 25 and 26. The casings 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 containing 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 raw material gas is activated by the energy of the turned rare gas, and the raw material gas (for example, methane) is hardly directly activated. is there. Further, the unnecessary gas is exhausted from the exhaust system 19 (see FIG. 4).

The introduced rare gas-based gas is sealed by an O-ring 24 so as not to leak from the 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, the gas may be flowed in this gap.

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

A cross section taken along the line AA 'in FIG. 1 is shown in 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 raw material gas (a gas mainly containing a rare gas) passes through the gap 32 and is converted into plasma in the gap 32. Then, a beam-shaped plasma is ejected 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, the plasma generator shown in FIG. 1 (shown by 52 in FIG. 5) is shown in FIG.
4 are staggered to form a uniform film. The four plasma generators 52 are shown in FIG.
Of the power sources 12 to 13.
A high frequency of 56 MHz is supplied at 500 W each. Plasma is generated in the region indicated by 51, and film formation is performed in that region. In this embodiment, by using helium as the rare gas and methane as the source gas,
A coating film containing carbon as a main component can be formed.

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, and its temperature is 100 ° C. or lower. Therefore, even if the gas is a polymer substrate material, there is no problem and good film formation can be performed.

A bias power supply 42 shown in FIG. 4 may be used to apply a DC or AC (high frequency) bias voltage to the surface to be formed. Further, a magnetic field may be applied to the formation surface so that the beam-shaped plasma is effectively ejected to the formation surface.

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

The film containing carbon as a main component is formed at a passing speed in association with the above-mentioned two steps, and the film is formed at a rate of about 20.
A film containing carbon as a main component and having a film thickness of 0Å is formed. The polymer substrate material 3 for which film formation has been completed is collected by the winding roll 14 via the free roller guide 4.

In carrying out the present invention, the treatment before the formation of the magnetic layer may be carried out by using 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 prepared in this example was cut into a tape having a width of 8 mm, and the reproduction output and the durability were evaluated using an 8 mm VCR of the market. When the film thickness was 200 Å or more, stable reproduction output with excellent running stability and still durability and less drop-up was obtained.

Further, it was confirmed that excellent durability was exhibited in continuous and intermittent tests of special reproducing operation in addition to regular reproducing operation.

[Embodiment 2] This embodiment is an example in which the reaction product is not attached to the coaxial discharge electrode portion in the construction shown in Embodiment 1. The present embodiment is different from the configuration shown in the first embodiment in that the central conductor (center electrode 31) is hollow and the source gas is allowed to flow through the hollow portion 30, as shown in FIG. Note that FIG. 3 is a schematic view of a cross section cut along AA ′ in FIG.

When such a structure is adopted, the gap 32
A rare gas (for example, helium) is flown into the hollow part 30, and a raw material gas (for example, methane) is flowed through the hollow portion 30. Hollow part 3
At 0, no discharge occurs so that the raw material gas is not activated here and is discharged to the outside of the device. On the other hand, the rare gas flowing through the gap 32 is turned into plasma by the high frequency discharge performed between the central conductor 31 and the outer conductor 29. Then, the raw material gas which has not been activated at the place where it exits the apparatus is wrapped coaxially with the rare gas that has been made into plasma, and is activated or made 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 flake is generated can be basically eliminated. Further, since the raw material gas is surrounded by the rare gas that is turned into plasma outside the device, the collection efficiency can be extremely increased.

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

The apparatus shown in FIG. 6 has parallel plate electrodes, and the plasma generated by the parallel plate electrodes is drawn out of the apparatus as plate-shaped plasma, and this sheet-shaped plasma is used.

In FIG. 6, the parallel plate electrode portion is composed of 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, and the insulator plate 6 is used.
3 is quartz glass, and the outer casing 62 is stainless steel. The electrode plate 61 has three Teflon shields 620, 62.
It is insulated from the others by 1, 622 and is connected to the MHV coaxial connector 611. An AC electric field (13.56NHz) 64 (corresponding to 42 in FIG. 4) is applied to the electrode plate 61 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,
It is supplied through a gas groove engraved in a Teflon insulator 613. The Teflon insulator 613 also has a role of preventing discharge in an unnecessary place. The outer casing 62 and the electrode plate holder 616 are fixed by screws on a 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 casing 62. The width of the facing insulator plate, that is, the width of the discharge portion (the length in the depth direction of the electrode in FIG. 6) is 25 mm, and the insulator thickness is 1.0 mm. The electrode interval is 5 mm, and the electrode length (the length in the vertical direction in FIG. 6) is 30 mm. Therefore, approximately 5 mm x 2
A sheet-type plasma of 5 mm will be generated.

100 sccm of helium was supplied to the above apparatus, and the frequency was 13.56 MHz at a pressure of 100 Torr.
When a high-frequency power of 500 W was applied, a stable discharge was obtained over the entire width of the discharge part, and sheet-shaped (plate-shaped) plasma could be emitted to the outside of the device. Even if this state was maintained for 10 minutes or longer, no trouble such as overheating occurred on the device.

The temperature of the plasma formed by the discharge was measured by blowing the plasma onto a thermocouple, and the temperature was about room temperature to 70 ° C. From this, it is confirmed that low-temperature glow discharge is being performed.

When the structure shown in FIG. 4 is used, a raw material gas such as methane or ethylene may be supplied as an additional gas.
Further, in order to increase the film formation rate or increase the film formation area, a plurality of devices may be arranged as shown in FIG.

[Embodiment 4] The present embodiment is an example in which the portion indicated by 41 in FIG. 4 is configured as shown in FIG. Figure 8
In the above, 81 is a film-shaped substrate. An example of such a film-like substrate is a tape of a magnetic storage medium. Reference numeral 82 denotes a cathode electrode, which is connected to the high frequency power supply 87 via a matching box 86. Reference numeral 85 is a cylindrical electrode that constitutes an anode electrode and is grounded. A high frequency discharge is generated in the plasma reaction space 89 between the anode electrode 85 and the cathode electrode 82. Further, the anode electrode 82 rotates so that the film-shaped substrate 81 moves smoothly. 83 is an insulator. Reference numeral 84 is a gas introduction pipe, and the raw material gas, the dilution gas, and the additional gas are
The gas is introduced into 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 in 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 an organic resin film having a width of 10 inches on which a metal magnetic material is vapor-deposited is used as the film-shaped substrate 81 and a hard carbon film is formed on the surface thereof to a thickness of 300Å will be described below. Here, the film-shaped substrate is 12 m /
It is assumed that the robot is moved at a min (20 cm / sec). In this case, the discharge space 89 having a width of 20 mm is covered by the film-shaped substrate.
It will move in 1 second. Therefore, in order to form a film with a thickness of 300Å, the film formation rate is 3000Å / sec.
Is required.

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

With the above film forming conditions,
A film forming rate of 0Å / sec can be obtained. And
It is possible to form a hard carbon coating on the surface of the film-shaped substrate 81 to a thickness of 300 Å.

The reason why C ₂ F ₆ is 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 becomes flakes and becomes an obstacle to film formation. Therefore, it is necessary to devise a method in which reaction products do not adhere to the cathode electrode.

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

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

Here, the reason why C ₂ F ₆ is used is that C ₂ F ₆ is used.
Has an etching action by F and a hard carbon film forming action by C. Here, CF ₄ can also be used as an additive gas. However, since CF ₄ does not have a film forming action on the hard carbon film, it is preferable to use C ₂ F ₆ which contributes to the film formation of the hard carbon film.

As described above, while the cathode electrode 82 is etched by the halogen-based gas, a film is formed on the substrate on the side of the anode electrode 85, so that the reaction product is not attached to the cathode electrode 82. A film can be formed on the surface of the film-shaped substrate 81.

[0099]

According to the present invention, it is possible to provide a device 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 past, a carbon film having a sufficiently high hardness could not be formed on the side of the ground electrode. However, according to the present invention, sufficient wear resistance and lubrication are obtained even when the carbon film is in contact with the anode which is the ground electrode. It is possible to provide a device capable of forming a carbon film having properties.

Further, according to the present invention, it is possible to provide an apparatus capable of high-speed film formation to the extent that a hard carbon film as a protective film can be formed at the same time as the magnetic layer manufacturing process.

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

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

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

[Brief description of 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 shows a cross section taken along the line A-A ′ in FIG.

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

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

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

FIG. 7: Pressure and electron temperature (Te), and the minimum voltage required to maintain pressure and plasma (Sustaining)
(Voltage) is shown.

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

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

[Explanation 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 ・ ・ Grounding 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 region 17・ ・ Sheet beam type plasma area 18 ・ ・ Source gas supply system 19 ・ ・ Exhaust system 20 ・ ・ Buffer chamber 21 ・ ・ MHV plug 31 ・ ・ Center conductor 33 ・ ・ Cylindrical insulator 29 ・ ・ Outer conductor 30 ・ ・Gas inlet 22 ·· Teflon insulator 27 ·· Teflon insulator 23 ·· Case 28 ·· Case 25 ·· Jig 26 ·· Jig 52 ·· Plasma generator 42 ·· Bias power supply 61 ·・ Electrode plate 63 ... Edge plate 62 ... Outer casing 81 ... Film substrate 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 plug 612. Gas inlet 616. Holder 617. Top plate 613. Teflon insulator

Claims (6)

[Claims] 1. A first electrode to which a high frequency electric field is applied,
The grounded second electrodes are arranged to face each other, a plasma is generated between the first and second electrodes by applying a high frequency electric field, and the raw material gas introduced into the plasma is activated to form a film. In the film forming apparatus to be formed, the distance between the first electrode and the second electrode is 6 mm or less, and the pressure between the electrodes is between 15 Torr and 100 Torr. 2. A grounded cylindrical second electrode facing the first electrode, and a film, which is a substrate on which a coating is to be formed, is wrapped around a part of the second electrode. The
When the cylindrical second electrode rotates, the film has a mechanism for passing between the first and second electrodes, and a high-frequency electric field is applied to the first electrode to apply the high-frequency electric field to the first electrode. The space between the first and second electrodes is turned into plasma,
In a film forming apparatus for activating a raw material gas introduced into the plasma to form a film, a peripheral end portion of the first electrode is covered with an insulator to insulate the first electrode and the second electrode from each other. The body substantially constitutes a closed space, gas is supplied to the closed space through the pores provided in the first electrode, and plasma is confined in the closed space to prevent leakage to the outside. And a gap between the first electrode and the second electrode is 6 mm or less, and a pressure in the closed space is between 15 Torr and 100 Torr. apparatus. 3. A grounded cylindrical second electrode facing the first electrode, and a film, which is a substrate on which a coating is to be formed, is wrapped around a part of the second electrode which is grounded. The
By rotating the cylindrical second electrode, the film has a mechanism for passing between the first and second electrodes, and applying a high-frequency electric field to the first electrode to apply the high-frequency electric field to the first electrode. The space between the first and second electrodes is made into plasma,
In the film forming apparatus which activates the raw material gas introduced into the plasma to form a film, the electric field strength formed by the first electrode with respect to the second electrode is the highest on the surface of the first electrode. The electrode is configured to be strong 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 and the second electrode are The pressure between the two electrodes is 1
A film forming apparatus, which is between 5 Torr and 100 Torr. 4. A first electrode to which a high frequency electric field is applied,
The grounded second electrodes are arranged to face each other, a plasma is generated between the first and second electrodes by applying a high frequency electric field, and the raw material gas introduced into the plasma is activated to form a film. A film forming apparatus for forming, wherein the cylindrical metal is arranged such that plasma generated between the first and second electrodes is blown onto a grounded metallic surface of the cylinder. A film forming apparatus having a mechanism in which a film, which is a substrate on which a film is to be formed, is wound around a part of the film, and the cylindrical metal is rotated so that the film passes through a plasma region where the film is sprayed. In, the distance between the first electrode and the second electrode is 6
The film forming apparatus is characterized in that it is less than or equal to mm and the pressure between the first electrode and the second electrode is between 15 Torr and 100 Torr. 5. The gas supplied into the plasma space according to claim 1, wherein the gas is a mixed gas of hydrogen and a gas selected from the group consisting of hydrocarbon, carbon halide and halogenated hydrocarbon, or The film forming apparatus according to each claim, wherein the film forming apparatus is a mixed gas of the mixed gas and a rare gas. 6. The film forming apparatus according to claim 2, wherein the film that is the base is a conductive film.