JP2006225711A - Apparatus for forming carbon film and method for manufacturing vessel having inner face coated with carbon film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for forming a carbon film which is less colored, has higher transparency and has a gas barrier property, and to provide a method for manufacturing a vessel having an inner face coated with the carbon film. <P>SOLUTION: This carbon-film-forming apparatus has: an outer electrode 6 having such a size as to surround a periphery of a vessel B of an article to be treated when the vessel is inserted; a gas exhaust pipe 10 which is attached to an edge face of the outer electrode 6 in the opening side of the vessel B, through a cylindrical dielectric member 8; an inner electrode 18 which is inserted into the vessel B in the outer electrode 6 from the gas exhaust pipe 10 side of the outer electrode and is connected to a grounding side; an exhaust means which is attached to the gas exhaust pipe 10; a gas supply means for supplying a medium gas to the inner electrode 18; and a high-frequency power source 13 connected to the outer electrode 6, wherein the outer electrode 6 is galvanically short-circuited to a ground through a coil 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a carbon film forming apparatus having a gas barrier property that is soft and highly transparent in a container such as a resin, and a method for manufacturing an inner surface carbon film coated container.

  In recent years, for example, a PET (PET) bottle, which is one of plastic containers, has a DLC (Diamond Like) on its inner surface in order to prevent the permeation of oxygen from the outside and the permeation of carbon dioxide from the inside (for example, carbonated drinking water). Attempts have been made to coat a hard carbon film such as Carbon) (Patent Documents 1 and 2).

  An apparatus according to Patent Document 2 which is a basic invention for coating a carbon film on a plastic container using high-frequency plasma CVD will be described with reference to FIG. FIG. 8 is a cross-sectional view of a carbon film coating apparatus for a plastic container using high-frequency plasma CVD described in this publication.

As shown in FIG. 8, a cylindrical support member 2 mounted on the base 3 and having flanges 1a and 1b at the upper and lower ends and serving as an earth shield, and disposed in the cylindrical cylindrical support member 2 A bottomed cylindrical external electrode 6 comprising an external electrode body 4 and an external electrode bottom member 5 having a space in which the container B can be accommodated, and the base 3 and the external electrode member 5. A flat dielectric member 7 disposed therebetween, and a cylindrical dielectric member that is placed on the upper surface of the external electrode 6 so that the upper surface thereof is flush with the upper flange 1a of the cylindrical support member 2 8, a gas exhaust pipe 10 screwed to the upper flange 1a of the cylindrical support member 2 and having upper and lower flanges 9a, 9b, and attached to the upper flange 9a to close the inside and connect to the installation side For example, frequency 1 is applied to the lid body 12 and the external electrode 6. A high-frequency power source 13 that supplies high-frequency power of 3.56 MHz through the cable 14, the matching unit 16, and the power supply terminal 15 is provided.
Here, the external electrode 6 includes a metal external electrode body 4 and a metal external electrode bottom member 5 having a flat plate shape that is detachably and sealably attached to the bottom of the external electrode body 4. It is configured.
Further, the external electrode bottom member 5, the flat dielectric member 7 and the base 3 are integrally moved up and down with respect to the external electrode body 4 by a pusher (not shown) to open and close the bottom of the external electrode body 4. To do.

Also, as shown in FIG. 8, a cylindrical spacer 31 made of a dielectric material having a cavity corresponding to the mouth and shoulder of the container B inserted therein is an upper portion of the main body 4 in the external electrode 6. Has been inserted. The spacer 31 is fixed by a screw (not shown) screwed from a cylindrical dielectric member 8 (described later) placed thereon. When the container B is inserted from the bottom side of the external electrode body 4 by inserting and fixing the cylindrical spacer 31 to the upper part of the body 4 in the external electrode 6 in this way, the mouth and shoulder of the container B are The other container B part is accommodated in the external electrode 6 in the cavity 48 of the spacer 31.
Examples of the dielectric material constituting the spacer 31 include plastic or ceramic. Various plastics can be used, and a fluorine-based resin such as polytetrafluoroethylene having a low high-frequency loss and excellent heat resistance is particularly preferable. As the ceramic, alumina, steatite with low high-frequency loss, or Macor with high machinability is preferable.

  The branch gas exhaust pipe 11 is connected to the side wall of the gas exhaust pipe 10, and an exhaust facility such as a vacuum pump (not shown) is attached to the other end.

  A method for coating a carbon film on a bottle using the apparatus having such a configuration will be described.

First, the container B is inserted into the external electrode body 4 of the external electrode 6, and then the gas in the external electrode 6 is exhausted from the gas exhaust pipe 11. At this time, the gas in the space inside and outside the container B housed in the external electrode 6 is exhausted. After reaching the specified degree of vacuum (representative value: 10 ⁻² to 10 ⁻⁵ Torr), medium gases (eg alkanes such as methane, ethane, propane, butane, pentane, hexane; ethylene, propylene, butene, pentene, Alkenes such as butadiene; alkynes such as acetylene; aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, etc.) are supplied from the gas supply pipe 17 to the internal electrode 18, and the gas blowing pipe 20 of the internal electrode 18 is further supplied. And blow out into the container B. The pressure in the container B is set to, for example, 2 × 10 ⁻¹ to 1 × 10 ⁻² Torr depending on the balance between the gas supply amount and the exhaust amount. Thereafter, high frequency power of 50 to 1000 W is applied from the high frequency power source 13 to the external electrode 6 through the matching unit 16 and the power supply terminal 15.

  By applying such high frequency power to the external electrode 6, plasma is generated between the external electrode 6 and the internal electrode 18. At this time, since the container B is accommodated in the space formed by the external electrode 6 and the cylindrical spacer 31 with almost no gap, plasma is generated in the container B. The medium gas is dissociated or further ionized by the plasma to generate a film-forming seed for forming a carbon film, and this film-forming seed is deposited on the inner surface of the container B to form a hard DLC film. . After the hard DLC film is formed to a predetermined thickness, the application of high-frequency power is stopped, the supply of medium gas is stopped, the residual gas is exhausted, nitrogen, a rare gas, air, or the like is supplied into the external electrode 6. This space is returned to atmospheric pressure. Thereafter, the container B is removed from the external electrode 6. In this method, it takes 1 to 3 seconds to form a carbon film with a thickness of 30 nm.

JP-A-8-53116 JP 2003-286571 A

However, since the film formed on a container such as a PET bottle is a hard DLC film, there is a problem that when the bottle is largely deformed due to dropping or the like, the amount of deformation cannot be followed and cracks occur. Moreover, hard DLC will be colored and there exists a problem that the bottle which has the gas barrier property with a good appearance cannot be formed.
Therefore, the carbon film coated on the container is preferably soft. In view of the diversification of beverage products in recent years, the appearance of a container having gas barrier properties with a highly transparent carbon film is desired.

  In view of the above problems, an object of the present invention is to provide a carbon film forming apparatus and an inner surface carbon film coated container manufacturing method that have a gas barrier property that is less colored and is softer and more transparent.

  According to a first aspect of the present invention for solving the above-described problem, an external electrode having a size surrounding the outer periphery of the container and a mouth portion of the container are positioned when a container as an object to be processed is inserted. An exhaust pipe attached to the end face of the external electrode on the side to be connected via a dielectric member, an exhaust means attached to the exhaust pipe, a gas supply means for supplying a medium gas to the container, and the external The carbon film forming apparatus includes a high frequency power source connected to an electrode, and the external electrode is DC short-circuited to a ground with a coil.

  A second invention is the carbon film forming apparatus according to the first invention, wherein the impedance of the coil is 9 times or more of a discharge impedance.

  According to a third aspect of the present invention, there is provided the carbon film forming apparatus according to the first aspect, further comprising an internal electrode inserted into the container in the external electrode from the exhaust pipe side and connected to the ground side. .

  A fourth invention is the carbon film forming apparatus according to the third invention, wherein the internal electrode also serves as a gas supply means.

  In a fifth aspect of the invention, in coating the object to be processed with the carbon film forming apparatus of the first invention, (a) a step of inserting a container as the object to be processed into the external electrode; b) exhausting the gas inside and outside the container through the exhaust pipe means through the exhaust pipe, and then supplying a medium gas to the container by the gas supply means to set the inside of the container at a predetermined gas pressure; and (c) A high-frequency power from a high-frequency power source is supplied to an external electrode formed by DC short-circuiting with the ground, and plasma is generated in the container, and the medium gas is dissociated by the plasma to the inner surface of the container. And a step of coating the carbon film.

  6th invention WHEREIN: After the process inserted in the said external electrode in 5th invention, the process of inserting an internal electrode so that it may be located in the bottom part side of the said container is further included, The inner surface carbon characterized by the above-mentioned It exists in the manufacturing method of a film coating container.

  According to the present invention, by connecting a coil between the external electrode and the ground, it is short-circuited in a direct current, prevents the occurrence of negative bias to the external electrode, softens the carbon film and reduces coloring, A highly transparent container can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment and an Example. In addition, constituent elements in the following embodiments and examples include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[Embodiment of the Invention]
FIG. 1 is a cross-sectional view showing a carbon film forming apparatus on the inner surface of a plastic container according to this embodiment.

  As shown in FIG. 1, the carbon film forming apparatus on the inner surface of the plastic container according to the present embodiment includes an external electrode 6 having a size surrounding the outer periphery of the container B when the container B, which is an object to be processed, is inserted; A gas exhaust pipe 10 attached to the end face of the external electrode 6 on the side where the mouth of the container B is located via a cylindrical dielectric member 8, and the gas exhaust into the container B in the external electrode 6 An internal electrode 18 inserted from the tube 10 side and connected to the ground side; an exhaust means attached to the gas exhaust pipe 10; a gas supply means for supplying a medium gas to the internal electrode 18; A high-frequency power source 13 connected to the electrode 6, and the external electrode 6 is formed by DC short-circuiting between the external electrode 6 and the ground.

  Here, the cylindrical support member 2 having flanges 1 a and 1 b at the upper and lower ends and serving also as an earth shield is placed on the base 3. A cylindrical metal external electrode body 4 is disposed in the cylindrical support member 2. A flat plate-like metal external electrode bottom member 5 is detachably attached to the bottom of the external electrode main body 4 and can be sealed. The external electrode body 4 and the external electrode bottom member 5 constitute a bottomed cylindrical external electrode 6 having a space of a size capable of installing a plastic container (for example, a plastic bottle) B that forms a carbon film. The flat dielectric member 7 is disposed between the base 3 and the external electrode bottom member 5.

  The external electrode bottom member 5, the flat dielectric member 7 and the base 3 are integrally moved up and down with respect to the external electrode main body 4 by a pusher (not shown) to open and close the bottom of the external electrode main body 4. To do.

The flat dielectric member 8 is placed on the upper surface of the external electrode 6 so that the upper surface of the flat dielectric member 8 is flush with the upper flange 1 a of the cylindrical support member 2. The gas exhaust pipe 10 having upper and lower flanges 9 a and 9 b is screwed to the upper flange 1 a of the cylindrical support member 2, so that the gas exhaust pipe 10 is fixed to the cylindrical support member 2. Further, by screwing a screw (not shown) from the lower flange 9b of the gas exhaust pipe 10 through the cylindrical dielectric member 8 to the external electrode body 4 of the external electrode 6, the gas exhaust pipe 10 is While being fixed to the flat dielectric member 8 and the external electrode 6, the cylindrical dielectric member 8 is also fixed to the external electrode 6. The gas exhaust pipe 10 and the dielectric member 8 and the external electrode 6 are fixed with a certain thickness so that the gas exhaust pipe 10 and the external electrode 6 are not short-circuited with screws at high frequency. It is isolated by a dielectric and has a structure that does not contact.
The inductance of the coil 21 is adjusted by the inner diameter, the number of turns, etc. As an example, a Teflon (registered trademark) coated wire having a conductor diameter of 0.5 mm is used, and an inner diameter of 20 mm and about 30 turns are used. Moreover, in order to improve insulation and stability, it may be fixed or filled with an adhesive or the like.

  Further, in the present embodiment, the gas exhaust pipe 10 and the external electrode 6 are short-circuited by a coil 21 provided in a space formed in a part of the cylindrical dielectric member 8, Electric power is not passed through, and the structure is short-circuited in terms of direct current.

  The branch gas exhaust pipe 11 is connected to the side wall of the gas exhaust pipe 10, and an exhaust facility such as a vacuum pump (not shown) is attached to the other end. The lid 12 is attached to the upper flange 9 a of the gas exhaust pipe 10.

  For example, a high frequency power supply 13 that outputs high frequency power with a frequency of 13.56 MHz is connected to the external electrode body 4 of the external electrode 6 through a cable 14 and a power supply terminal 15. The matching unit 16 is interposed in the cable 14 between the high-frequency power source 13 and the power supply terminal 15.

  The gas supply pipe 17 passes through the lid 12 and is inserted through the gas exhaust pipe 10 into a portion corresponding to the mouth portion of the container B in the external electrode body 4 of the external electrode 6. A substantially cylindrical metal internal electrode 18 is disposed near the bottom of the container B inserted into the external electrode 6, and its upper end is detachably attached to the lower end of the gas supply pipe 17. As shown in FIG. 1, the internal electrode 18 is a gas blowout part made of an insulating material for blowing out a medium gas at the bottom, with a gas flow path 19 cut out in the central axis, such as plastic or ceramic. A gas blowing tube 20 made of an insulating material is inserted.

  The diameter of the internal electrode 18 is not more than the diameter of the cap of the container B.

  The internal electrode 18 is made of a heat-resistant metal material such as tungsten or stainless steel, but may be made of aluminum. If the surface of the internal electrode 18 is smooth, the carbon film deposited on the surface of the internal electrode 18 may be easily peeled off. For this reason, it is preferable that the surface of the internal electrode 18 is previously sandblasted to increase the surface roughness and make it difficult to peel off the carbon film deposited on the surface. However, the method of smoothing the surface also has the advantage that the internal carbon cleaning becomes unnecessary if the carbon film deposited is made very easy to peel off and does not remain on the internal electrode.

  Next, a method for producing an inner surface carbon film-coated plastic container will be described using the carbon film forming apparatus shown in FIG.

  The external electrode bottom member 5, the flat dielectric member 7 and the base 3 are removed by a pusher (not shown) to open the bottom of the external electrode body 4. Subsequently, after the container B is opened from the bottom side of the external electrode body 4 through the mouth side of the container B, the external electrode bottom member 5 and the flat dielectric are placed on the bottom side of the external electrode body 4 by a pusher (not shown). By attaching the member 7 and the base 3 in this order, the container B is accommodated in the internal space of the external electrode 6 including the external electrode main body 4 and the external electrode bottom member 5 as shown in FIG. At this time, the container B communicates with the exhaust pipe 10 through its mouth.

  Next, the gas exhaust pipe 10 and the gas inside and outside the container B are exhausted through the branch gas exhaust pipe 11 and the gas exhaust pipe 10 by an exhaust means (not shown). Subsequently, the medium gas is supplied from the gas supply pipe 17 to the gas flow path 19 of the internal electrode 18 and blown into the container B from the gas blowing pipe 20 made of an insulating material inserted into the bottom of the internal electrode 18. This medium gas further flows toward the mouth of the container B. Subsequently, the gas supply amount and the gas exhaust amount are balanced, and the inside of the container B is set to a predetermined gas pressure.

  Next, high-frequency power having a frequency of 13.56 MHz, for example, is supplied from the high-frequency power source 13 to the external electrode body 4 of the external electrode 6 through the cable 14, the matching unit 16 and the power supply terminal 15. At this time, plasma is generated around the internal electrode 18. Due to the generation of such plasma, the medium gas is dissociated by the plasma, and the inner surface of the container B in the external electrode 6 is coated with a uniform carbon film with a uniform thickness.

  After the thickness of the carbon film reaches a predetermined film thickness, the supply of the high frequency power from the high frequency power supply 13 is stopped, the supply of the medium gas is stopped, the residual gas is exhausted, and the exhaust of the gas is stopped. , Nitrogen, rare gas, air, or the like is supplied from the gas supply pipe 17 into the container B through the gas flow path 19 and the gas blowing pipe 20 of the internal electrode 18, and the inside and outside of the container B are returned to atmospheric pressure, and the inner surface carbon film Remove the coated container. Thereafter, the container B is exchanged according to the above-described order, and the next container coating operation is started.

Here, when plasma is generated between the external electrode 6 and the internal electrode 18, electrons do not accumulate on the inner wall surface of the external electrode 6 short-circuited in a direct current by the short-circuit coil. There is no self-bias to a negative potential. As a result, a large potential drop does not occur on the external electrode 6 side.
At this time, due to the presence of acetylene gas as a carbon source in the plasma, the positively ionized carbon source is less likely to collide with the inner wall surface of the container 20 positioned in the external electrode 6 and the energy is small. Become. For this reason, since the ion impact which the carbon film formed on the inner wall surface of the container B receives becomes small, the formed carbon film becomes a soft carbon film having a hardness of 10 GPa or less.

  The impedance of the coil 21 is preferably at least 9 times the discharge impedance, more preferably 12 times or more, as shown in the examples described later.

Here, the soft carbon film obtained in the present invention is a fine hardness measurement in which graphite (carbon atom bond is SP ² bond) is more mixed than diamond (carbon atom bond is SP ³ bond). In the law, it means 10 GPa or less.

  In addition to the microhardness measurement method, for example, the S (graphite-like component) / N (polymer component) ratio (hereinafter referred to as “Raman S / N ratio”)) by Raman spectroscopy is 1.0 or less, more preferably. The case where the Raman S / N ratio is in the range of 1.0 or less and 0.2 or more. This is because when the Raman S / N ratio exceeds 1.0, a hard film is formed, and yellow coloration becomes remarkable, and the transparency cannot be improved. Further, when the Raman S / N ratio is less than 0.2, the gas barrier property is deteriorated and the function as the gas barrier film cannot be exhibited.

  In the carbon film, the fluorescence intensity observed at the time of measurement is known to increase in proportion to the amount of hydrogen contained in the film, and the amount of hydrogen is compared by comparing the fluorescence intensity between samples. can do. As a method for predicting the amount of hydrogen, the intensity ratio (Raman S / S) of the fluorescence intensity of the carbon film (N: polymer component) and the peak intensity at the peak top (S: graphite-like component) when this fluorescence intensity is taken as the baseline. N ratio) is determined, and the smaller the Raman S / N ratio, the softer the carbon film, while the larger the Raman S / N ratio, the harder the carbon film.

  When measuring the intensity ratio, it is preferable to use total reflection Raman spectroscopy (ATR (Attenuated Total Reflection) -Raman) for the purpose of improving measurement sensitivity. Note that, as an example of laser conditions for measurement, an Ar ion laser is used as the laser device 102, the laser wavelength is preferably 515 nm, and the laser intensity is preferably 20 mW.

  As described above, the soft carbon film according to the present invention has high transparency and can maintain gas barrier properties by setting the Raman S / N ratio to 1.0 or less.

The b ^* absolute value of the L ^* a ^* b ^* color system (JIS Z8729) is 7 or less, more preferably 7 or less and 3.5 or more.
Here, when b ^* absolute value exceeds 7, coloring is dark, lacks in transparency, and the appearance of the product actually filled with the beverage is poor.
The L ^* a ^* b ^* color system is measured according to JIS Z8729.
The a ^* absolute value of the L ^* a ^* b ^* color system (JIS Z8729) is 1 or less.

  Here, the microhardness of the multilayer carbon film under the condition that the Raman S / N ratio is 1.0 or less is 10 GPa or less. The measurement of the microhardness of the multilayer carbon film will be described later in “(2) Hardness” in Examples. At this time, the S / N ratio of the multilayer carbon film is 2.0 or less.

  Here, examples of the object to be treated in the present invention include a glass container, a ceramic container, a paper container and the like in addition to a resin container such as a so-called plastic.

  Examples of the container include a container filled with fuel such as a gasoline tank. In addition, examples of other containers include a plastic container for pharmaceuticals and a plastic container for food.

Further, in an organic electronic device such as an organic transistor, the functional material may be used as a protective film having a high necessity for protecting it from moisture or oxygen.
It is also effective as a gas barrier film for films and the like. Furthermore, you may have electronic materials, such as a light emitting layer and an electrode layer, for example. For example, as an electronic material, a carbon film may be used as a protective film of an organic EL (Organic Electro Luminescence or OLED (Organic Light Emitting Diode)) or an inorganic EL substrate.

  Here, examples of the resin include known materials such as polyester films such as polyethylene terephthalate, polyolefin films such as polyethylene, polypropylene, and polybutene, polystyrene films, polyamide films, polycarbonate films, and polyacrylonitrile film films.

  Here, the high-frequency power from the high-frequency power source 13 is, for example, 13.56 MHz, but can be 1 to 100 MHz, and is not particularly limited. The output is preferably 100 to 1000 W. The application of the high frequency power may be continuous or intermittent (pulsed).

  Here, the medium gas is basically hydrocarbon, for example, alkanes such as methane, ethane, propane, butane, pentane and hexane; alkenes such as ethylene, propylene, butene, pentene and butadiene; alkynes such as acetylene Aromatic hydrocarbons such as benzene, toluene, xylene, indene, naphthalene and phenanthrene; cycloparaffins such as cyclopropane and cyclohexane; cycloolefins such as cyclopentene and cyclohexene, and other carbon monoxide and carbon dioxide Etc. can also be used. Thereby, for example, a carbon film for preventing permeation of, for example, oxygen, water vapor, gasoline, etc. in the container can be coated. Further, the carbon film may be a film having a gradient function.

In the present embodiment, the coil 21 is disposed so as to short-circuit the upper flange 9a and the external electrode body 4, but the present invention is not limited to this.
For example, as shown in FIG. 2, the cylindrical support member 2 and the external electrode body 4 may be short-circuited by a coil 21. Further, as shown in FIG. 3, a first line 16a in which a first capacitor C1 and a first coil L1 are provided in series, and a second line in which a second capacitor C2 is provided in parallel to the first line 16a. In the matching device 21 including 16b, a second coil L2 for short-circuiting the first line 16a and the second line 16b may be provided.

As a result, when plasma is generated between the external electrode 6 and the internal electrode 18, if it is completely insulated by a dielectric member as in the prior art, electrons are formed on the inner wall surface of the insulated external electrode 6. Accumulates. Therefore, the external electrode 6 is self-biased to a negative potential as shown in FIG. On the external electrode 6 side, a potential drop of, for example, about 500 to 1000 V occurs due to the stored electrons. At this time, the presence of acetylene gas as a carbon source in the plasma causes the positively ionized carbon source to selectively collide with the inner wall surface of the container B positioned along the external electrode 6. By bonding adjacent carbons, a hard carbon film made of an extremely dense DLC film is formed on the inner wall surface of the container B.
On the other hand, in the present embodiment, electrons do not accumulate on the inner wall surface of the external electrode 6 short-circuited in a direct current by the short-circuit coil. There is no bias. As a result, a large potential drop does not occur on the external electrode 6 side.

  As described above, according to the present embodiment, electrons do not accumulate on the inner wall surface of the external electrode 6 short-circuited in a direct current by the short-circuit coil, so that the external electrode 6 has a negative potential as shown in FIG. As a result, a large potential drop does not occur on the external electrode 6 side. As a result, the positively ionized carbon source does not collide with the inner wall surface of the container B, and the energy is small. . For this reason, since the ion impact received by the carbon film formed on the inner wall surface of the container B is reduced, the carbon film formed on the inner surface of the container can be a soft carbon film having a hardness of 10 GPa or less. As a result, a soft carbon film can be obtained, so that the occurrence of cracks on the inner wall surface of the container and the improvement of transparency can be obtained.

In this embodiment, the internal electrode 18 inserted into the container B is used for discharging, but the present invention can be achieved without positively using the internal electrode. That is, the introduced medium gas can be ionized by generating plasma in the gas exhaust pipe 10 and the external electrode 6 connected to the ground side.
In the present embodiment, the internal electrode and the gas supply means for supplying the medium gas are also used, but may be provided separately.

Hereinafter, although the suitable Example which shows the effect of this invention is described, this invention is not limited to this Example.
In this embodiment, the coil installation location of the coil is within the matching unit shown in FIG.
The capacity of the container used was 500 cc, the film forming pressure was 100 mTorr, the gas flow rate was 90 sccm, the RF power was 900 W, and the frequency was 13.56 MHz.

(1) The discharge parameters in this example are as follows.
Applied voltage Vpk: 1021 V (Here, the applied voltage was measured by bringing a high voltage probe into contact with an external electrode.)
Discharge impedance Zd: 290Ω (Here, the discharge impedance was obtained from the impedance of the matching device by phase conjugation.)
Discharge current Ipk: 3.4 A (Here, the discharge current was calculated from the applied voltage and the discharge impedance.)

(2) Hardness Since the method of measuring hardness is as thin as about 20 to 50 nm, the hardness of the carbon film cannot be directly measured. Therefore, the film formation was repeated a plurality of times to form a simulated film as a multilayer film (200 nm or more), and this hardness was measured by a nanoindentation test in which the hardness of a known ultrathin film was measured.
The test piece was formed by inserting a base material into a plastic container and repeating film formation on the base material a plurality of times.
For the measurement, a nano indenter (NanoIndenter TMXPsyDCM, a trademark of MTS Systems) manufactured by MTS Systems was used. In this nano-indentation test, a triangular pyramid (Berkovic type) indenter made of a diamond tip is pushed into the surface of the object to be measured, and the load P applied to the indenter at that time and the oblique area A under the indenter are used to make a microhard (GPa) is obtained. 10 GPa or less is a soft film.

Table 1 shows the coil inductance used for film formation, and the coil impedance, hardness, film formation speed, and barrier properties obtained by converting the inductance at a frequency of 13.56 MHz.
FIG. 5 shows the relationship between the coil inductance used for film formation, the film formation speed, and the hardness. FIG. 6 shows the relationship between the coil impedance, film formation speed, and hardness, with the horizontal axis of FIG. Each relationship diagram is shown.

  As shown in Table 1 and FIG. 5, when the coil inductance was set to 30 μH or more, the film formation rate was equal to or more than 90% of 200 Å / s, when the coil formation rate was no coil. . This is presumably because the coil has a sufficient impedance, so that high-frequency power loss is small.

  Further, the barrier properties of the film were all 10 times or more when the coil inductance was 30 μH or more at which the sufficient film forming speed was obtained.

Furthermore, as shown in Table 1, these films were all soft films having a hardness of less than 10 GPa. In addition, a highly transparent film having a color difference b * value of 7 or less was obtained.
On the other hand, when there was no coil, it was a hard film exceeding 13 GPa and 10 GPa.

As a result, it has been found that if the coil inductance is 30 μH or more, a sufficient film forming speed and barrier property can be obtained.
On the other hand, if the coil inductance exceeds 3000 μH, it is difficult to produce a coil, and an inductance less than this is preferable.

  Next, the relationship between the coil inductance and the coil impedance when the frequency is changed will be described with reference to Table 2.

The film forming conditions were the same as those described above except for the frequency.
The frequency was 1 to 100 MHz.
FIG. 7 shows the relationship between the high frequency used for film formation, the discharge impedance when there is no coil, the required coil impedance, and the impedance ratio which is the ratio of the discharge impedance to the required coil impedance. Here, the required coil impedance is the minimum coil required to obtain a film formation speed of 90% or more and barrier properties when the minimum coil is attached, compared to the film formation speed when the coil is not used. Impedance.

  As a result, as shown in Table 2 and FIG. 7, the impedance required for the coil is 10 GPa or more without the coil, but at least 9 times the discharge impedance, more preferably 12 times the impedance. By attaching a coil having, a soft film of 10 GPa or less can be obtained without deteriorating the film forming speed and barrier property in all frequency ranges, and crack generation can be suppressed and transparency can be improved. In addition, a highly transparent film having a color difference b * value of 7 or less was obtained.

When these bottles were actually filled with beverages and subjected to a drop test, it was confirmed that the occurrence of cracks was drastically reduced compared to conventional hard films. In addition, it was confirmed that the transparency was at a level with no problem.
It is not preferable that the coil impedance exceeds 1000 times the discharge impedance because the coil becomes larger than necessary.

  As described above, the carbon film forming apparatus according to the present invention reduces the coloring of the carbon film formed on the object to be processed, makes the transparency better, and is suitable for use in manufacturing a container having a good gas barrier property. Yes.

It is the schematic of the film-forming apparatus concerning embodiment. It is the schematic of the other film-forming apparatus concerning embodiment. It is the schematic of the matching device of the film-forming apparatus concerning embodiment. It is a bias waveform diagram when there is a coil. It is a bias waveform diagram in the case of no coil. FIG. 5 is a relationship diagram of coil inductance, film formation speed, and hardness in film formation. FIG. 6 is a relationship diagram of coil impedance, film formation speed, and hardness in film formation. It is a relationship figure of the frequency in film-forming, coil impedance, and impedance ratio. It is the schematic of the film-forming apparatus concerning a prior art.

Explanation of symbols

B container 2 cylindrical support member 3 base 4 external electrode main body 5 external electrode bottom member 6 external electrode 7 flat dielectric 8 annular dielectric member 10 gas exhaust pipe 13 high frequency power supply 15 power supply terminal 16 matching unit 31 cylindrical spacer

Claims (6)

  When a container, which is an object to be processed, is inserted, the external electrode having a size surrounding the outer periphery of the container and the end face of the external electrode on the side where the mouth of the container is located are attached via a dielectric member. An exhaust pipe, an exhaust means attached to the exhaust pipe, a gas supply means for supplying a medium gas to the container, and a high frequency power source connected to the external electrode, A carbon film forming apparatus comprising a coil and a direct current short circuit with a ground. In claim 1,
The carbon film forming apparatus, wherein the coil has an impedance of 9 times or more of a discharge impedance. In claim 1,
An apparatus for forming a carbon film, comprising: an internal electrode inserted into the container in the external electrode from the exhaust pipe side and connected to the ground side. In claim 3,
The carbon film forming apparatus, wherein the internal electrode also serves as a gas supply means. In coating the carbon film on the object to be processed using the carbon film forming apparatus according to claim 1,
(A) inserting a container which is an object to be processed into an external electrode;
(B) after exhausting the gas inside and outside the container through the exhaust pipe by the exhaust pipe means, supplying a medium gas to the container by the gas supply means, and setting the inside of the container to a predetermined gas pressure;
(C) supplying high-frequency power from a high-frequency power source to an external electrode formed by DC short-circuiting with the ground, generating plasma in the container, dissociating the medium gas by the plasma, and And a step of coating the inner surface of the container with a carbon film. In claim 5,
After the step of inserting into the external electrode, the method of manufacturing an inner surface carbon film-coated container further includes a step of inserting the internal electrode so as to be positioned on the bottom side of the container.

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