JP2004018904A - Remote type gas supplying apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply treating gas between facing electrodes by making uniformity of flowing rate of the treating gas, in remote type electrodes. <P>SOLUTION: A supplying apparatus for treating gas, is composed of a first vessel 11 connected to a treating gas supplying hole 10, a second vessel 12 arranged so as to include the whole body of the first vessel 11, and a third vessel 13 adjoined with the second vessel 12 through a gas passage 14 and connected to treating gas introducing holes 56 and 57 for the remote-type electrodes. The first vessel 11 is formed of a hollow cylindrical body 21 where the connecting part 22 of the treating gas supplying hole 10 and the end part 23 at the opposite side are closed, and the gas blowing-out holes 24 are formed at prescribed intervals P(P1-P3) along the longitudinal direction of this cylindrical body 21, so that the intervals P of the gas blowing-out holes 24 is gradually shorten toward the end 23 side from the connecting part 22 side (P1 > P2 > P3). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a discharge plasma processing apparatus for processing an object to be processed using discharge plasma generated under a pressure near body pressure, and more particularly, to uniformly supply a processing gas to a remote electrode. Related to a remote type gas supply device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a method of generating a glow discharge plasma under low-pressure conditions and modifying the surface of a processing target or forming a thin film on the processing target has been put to practical use. However, the processing apparatus under these low-pressure conditions requires a vacuum chamber, a vacuum evacuation apparatus, and the like, so that the surface processing apparatus becomes expensive, and is hardly used when processing a large-area substrate or the like. .
[0003]
Therefore, a discharge plasma processing apparatus has been proposed in which discharge plasma is generated under a pressure close to the atmospheric pressure, and the target plasma is processed using the discharge plasma.
[0004]
For example, JP-A-6-2149, JP-A-7-85997, and the like disclose a parallel plate type electrode (counter electrode) composed of an upper electrode and a lower electrode in a reaction vessel, and provide a space between the parallel plate type electrodes. A direct method in which an object to be processed is placed and a processing gas is introduced into the reaction tank, a discharge plasma is generated by applying a voltage between the parallel plate electrodes, and the object to be processed is processed by the discharge plasma. A plasma processing apparatus has been proposed.
[0005]
Also, as another processing apparatus, a remote-type plasma processing apparatus that places an object to be processed outside the discharge space and blows plasma from the discharge space onto the object to be processed, instead of disposing the object in the discharge space. Has been proposed.
[0006]
For example, Japanese Patent Application Laid-Open No. H11-335868 discloses that a discharge plasma is generated by applying an electric field between parallel plate-type counter electrodes and forcibly exhausting the vicinity of the surface of the object to be processed. A plasma processing apparatus has been proposed which conducts a process by guiding the surface of the object to be processed.
[0007]
By the way, in a discharge plasma apparatus using a remote type electrode that generates discharge plasma by applying an electric field between parallel plate-type counter electrodes, the processing gas is blown uniformly between the counter electrodes. A remote gas supply device is provided between the supply port and the processing gas introduction port of the remote electrode.
[0008]
The remote type gas supply device is for stably guiding the processing gas introduced from the processing gas supply port to the processing gas introduction port of the remote type electrode.
[0009]
As an example of such a gas supply device, Japanese Unexamined Patent Publication No. 8-279468 discloses a rectangular tubular body having a vertically long trapezoidal shape with a narrower planar shape toward the tip and a rectangular cross section orthogonal to the longitudinal direction. There has been proposed a gas supply device including a quartz hollow member made of quartz and a plurality of gas blowing holes formed on both side walls of the hollow member along the longitudinal direction of the hollow member.
[0010]
In Japanese Patent Application Laid-Open No. 9-129615, a processing gas diffusion chamber is provided below an upper electrode, and a processing gas supply passage for introducing a processing gas from the processing gas diffusion chamber to the processing chamber is provided from the center. A gas supply device (processing gas diffusion chamber) has been proposed in which the length of the upper electrode is reduced at a predetermined ratio toward the outer peripheral direction, so that the flow rate of each processing gas supply path is made uniform. I have.
[0011]
[Problems to be solved by the invention]
In any of the above gas supply devices, the processing gas is uniformly supplied into the processing chamber by devising the shape of the hollow member and the length of the processing gas supply path. The road itself is formed at a constant pitch. Further, these gas supply apparatuses are applied to a direct plasma processing apparatus, and do not have a structure applicable to a remote plasma processing apparatus, that is, a remote electrode.
[0012]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a remote-type gas supply device capable of supplying a processing gas at a uniform flow rate between remote electrodes in a remote-type electrode. .
[0013]
[Means for Solving the Problems]
The remote gas supply device of the present invention guides a processing gas introduced from a processing gas supply port to a processing gas introduction port of a remote electrode, and a first container connected to the processing gas supply port, A second container provided so as to include the entire first container, and a third container adjacent to the second container via a gas communication passage and connected to a processing gas inlet of the remote electrode. The first container is formed in a hollow cylindrical body whose end opposite to the connection portion of the processing gas supply port is closed, and has a predetermined interval along the longitudinal direction of the cylindrical body. And a gas blowing hole is formed. Further, the gap between the gas blowing holes is formed so as to gradually decrease from the connecting portion side toward the end portion side.
[0014]
According to the present invention having such characteristics, the second container has a function as a buffer for reducing the pressure of the processing gas blown out of the first container. That is, as the processing gas spreads in the container, the dynamic pressure decreases, and the influence of the flow of the processing gas is reduced. Here, the gas discharge holes formed on the peripheral side surface of the first container, which is a hollow cylindrical body, are formed such that the longitudinal gap therebetween gradually decreases from the connecting portion side toward the end portion side. In the first container formed in a cylindrical shape, the pressure generally increases from the connecting portion side to which the processing gas is supplied from the processing gas supply source toward the tip end. Therefore, in consideration of such a pressure distribution in the first container, the intervals at which the gas blowing holes are provided are formed so that the connecting portion side is sparse and the end portions are dense. Thereby, a processing gas having a uniform flow rate is blown into the second container from each gas blowing hole of the first container.
[0015]
Here, the volume of the second container is at least 5 times or more, for example, about 5 to 20 times the volume of the first container. By doing so, the function as a buffer of the second container can be sufficiently exhibited.
[0016]
Further, the width of the gas communication passage formed in the second container is formed to be equal to or wider than the width between the opposing electrodes of the remote electrode. By setting the width in this way, the processing gas can be smoothly introduced from the second container to the third container.
[0017]
Further, the volume of the third container is set to be the same as or smaller than the volume of the second container, and the width of the processing gas inlet of the remote electrode formed in the shape of a slit is set to the upper portion opening into the third container. From the side, it is formed so as to gradually decrease toward the lower side extending between the opposing electrodes of the remote type electrode. This makes it possible to make the flow of the processing gas introduced from the third container between the opposing electrodes of the remote electrode smoother and to make the flow velocity uniform.
[0018]
The remote-type electrode has a pair of electrodes facing each other at a predetermined interval, and applies an electric field between the counter electrodes each having a unique dielectric material provided on at least one electrode facing surface of the pair of electrodes. As a result, a glow discharge plasma is generated.
[0019]
Here, examples of the material of the counter electrode include a simple metal such as iron, copper, and aluminum, an alloy such as stainless steel and brass, and an intermetallic compound. The shape of the pair of electrodes constituting the counter electrode is not particularly limited, but is preferably a structure in which the distance between the counter electrodes is constant in order to avoid occurrence of arc discharge due to electric field concentration. More preferably, the space between the pair of electrodes has a parallel flat portion, and in particular, both the pair of electrodes preferably have a substantially planar shape.
[0020]
In the present invention, generation of a streamer can be suppressed by processing the end of each electrode of the counter electrode into a curved surface. The radius of curvature when performing the curved surface processing is not particularly limited, but is preferably 0.5 mm or more and less than the electrode plate thickness. If it is less than 0.5 mm, the effect of suppressing the occurrence of streamers is insufficient.
[0021]
In the present invention, the solid dielectric is placed on one or both of the electrode facing surfaces of the counter electrode. At this time, the solid dielectric and the electrode on the side to be installed are in close contact with each other, and the opposing surface of the contacting electrode is completely covered. If there is a portion where the electrodes directly face each other without being covered by the solid dielectric, arc discharge is likely to occur there.
[0022]
Examples of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, silicon dioxide, aluminum oxide, zirconium dioxide, metal oxides such as titanium dioxide, and double oxides such as barium titanate. Can be
[0023]
In particular, when a solid dielectric having a relative dielectric constant of 10 or more in a 25 ° C. environment is used, a discharge plasma at a low voltage and a high density can be generated, and the processing efficiency is improved. The upper limit of the relative permittivity is not particularly limited, but about 18,500 of actual materials are available. Particularly preferred is a solid dielectric having a relative dielectric constant of 10 to 100. Specific examples of the solid dielectric having a relative dielectric constant of 10 or more include metal oxides such as zirconium dioxide and titanium dioxide, and double oxides such as barium titanate.
[0024]
The thickness of the solid dielectric is preferably 0.01 to 4 mm. If it is too thick, a high voltage may be required to generate discharge plasma, and if it is too thin, dielectric breakdown may occur when a voltage is applied, and arc discharge may occur.
[0025]
The distance between the opposing electrodes is appropriately determined in consideration of the thickness of the solid dielectric, the magnitude of the applied voltage, the purpose of utilizing the plasma, and the like, and is preferably 0.1 to 5 mm. If it is less than 0.1 mm, it may not be sufficient to place the electrodes at intervals, while if it is more than 5 mm, it is difficult to generate uniform discharge plasma. More preferably, it is an interval of 0.5 to 3 mm in which discharge is easily stabilized.
[0026]
An electric field such as a high frequency wave, a pulse wave, or a microwave is applied between such opposed electrodes to generate plasma. However, it is preferable to apply a pulsed electric field. In particular, the rising and / or falling time of the electric field is preferably An electric field of less than 10 μs is preferred. If the time exceeds 10 μs, the discharge state easily shifts to an arc, and becomes unstable, making it difficult to maintain a high-density plasma state due to a pulsed electric field. The shorter the rise time and the fall time, the more efficiently the gas is ionized during the generation of plasma. However, it is actually difficult to realize a pulse electric field having a rise time of less than 40 ns. More preferably, it is 50 ns to 5 μs. Here, the rise time refers to the time during which the voltage (absolute value) continuously increases, and the fall time refers to the time during which the voltage (absolute value) continuously decreases.
[0027]
It is preferable that the electric field strength of the electric field be 10 to 1000 kV / cm. If the electric field intensity is less than 10 kV / cm, it takes too much time for the treatment. If the electric field intensity exceeds 1000 kV / cm, arc discharge is likely to occur.
[0028]
The frequency of the electric field is preferably 0.5 kHz or more. If the frequency is less than 0.5 kHz, the processing takes too much time because the plasma density is low. The upper limit is not particularly limited, but may be a high-frequency band such as 13.56 MHz that is commonly used and 50 MHz that is used experimentally. Considering the easiness of matching with the load and the handling, the frequency is preferably 500 kHz or less.
[0029]
The plasma processing apparatus using the remote electrode using the remote gas supply apparatus of the present invention can be used under any pressure, but when used for normal pressure discharge plasma processing, the effect can be sufficiently exerted. When used under a pressure near the atmospheric pressure, the effect is sufficiently exhibited.
[0030]
The above-mentioned pressure near the atmospheric pressure refers to a pressure of 1.333 × 10 ^{4 to} 10.664 × 10 ⁴ Pa. Above all, the pressure is preferably in the range of 9.331 × 10 ^{4 to} 10.297 × 10 ⁴ Pa, which facilitates pressure adjustment and simplifies the device configuration.
[0031]
Examples of the object to be processed in the present invention include plastics such as polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polyimide, liquid crystal polymer, epoxy resin, polytetrafluoroethylene, and acrylic resin, glass, ceramic, metal, and silicon wafer. And the like. Examples of the shape of the object to be processed include a plate shape and a film shape, but the shape is not particularly limited thereto. ADVANTAGE OF THE INVENTION According to this invention, it can respond | correspond to the process of the to-be-processed object which has various shapes easily.
[0032]
The processing gas used in the present invention is not particularly limited as long as it is a gas that generates plasma by applying an electric field, and various gases can be used according to the processing purpose.
[0033]
A water-repellent surface can be obtained by using a fluorine-containing compound gas such as CF ₄ , C ₂ F ₆ , CCIF ₃ , or SF ₆ as the processing gas.
[0034]
In addition, as a processing gas, an oxygen element-containing compound such as O ₂ , O ₃ , water, and air, a nitrogen element-containing compound such as N ₂ NH ₃ , and a sulfur element-containing compound such as SO ₂ and SO ₃ are used. By forming a hydrophilic functional group such as a carbonyl group, a hydroxyl group or an amino group on the surface of the body, the surface energy can be increased and a hydrophilic surface can be obtained. Further, a hydrophilic polymer film can be deposited using a polymerizable monomer having a hydrophilic group such as acrylic acid or methacrylic acid.
[0035]
Furthermore, using a processing gas such as a metal-hydrogen compound, a metal-halogen compound, or a metal alcohol of a metal such as Si, Ti, or Sn, a metal oxide thin film such as SiO ₂ , TiO ₂ , or SnO ₂ can be formed. it can.
[0036]
Furthermore, the surface of the object to be processed is given electrical and optical functions, organic substances are removed from the surface of the object, resist is removed, the adhesion of the polymer film is improved, and the glass-based substrate and the printed wiring board (FPC) are cleaned. It can be used for film formation, metal removal, desmear, ashing, etching, descum, sterilization cleaning, etc.
[0037]
From the viewpoint of economy and safety, it is preferable to perform the treatment in an atmosphere diluted with a diluting gas as described below, rather than in the atmosphere of the treatment gas alone. Examples of the diluting gas include rare gases such as helium, neon, argon, and xenon, and nitrogen gas. These may be used alone or in combination of two or more.
[0038]
According to such discharge plasma treatment, glow discharge plasma can be generated regardless of the type of gas existing in the plasma generation space. In the atmospheric pressure plasma treatment under a specific gas atmosphere as well as the plasma treatment under the known low pressure condition, it is essential to perform the treatment in a closed container shielded from the outside air. , Processing can be performed in an open system or in a low-confidential system to the extent that free flow of gas is prevented.
[0039]
ADVANTAGE OF THE INVENTION According to this invention, it is possible to generate a discharge under the atmospheric pressure directly between opposing electrodes, and implement | achieve a more simplified electrode structure, an atmospheric pressure plasma apparatus by a discharge procedure, and a processing method and high-speed processing. be able to. In addition, parameters relating to processing can be adjusted by parameters such as the frequency of an applied electric field, voltage, and electrode spacing.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0041]
1 to 4 show the structure of a remote electrode including the remote gas supply device of the present invention. FIG. 1 is a plan view showing a partial cross section, FIG. 2 is a side view showing a partial cross section, and FIG. 3 is a bottom view, and FIG. 4 is a cross-sectional view as seen from the side. FIG. 5 is a side view showing the appearance of the first container.
[0042]
First, the remote type electrode will be described.
[0043]
As shown in FIG. 4, the remote type electrode is provided with a parallel plate type counter electrode composed of a voltage application electrode 52 and ground electrodes 51 and 53 disposed on both sides of the voltage application electrode 52 in a housing 40. At least one electrode facing surface of the counter electrode is covered with a fixed dielectric. The glow discharge plasma generated in the discharge space 54 formed between the ground electrode 51 and the voltage application electrode 52 and the discharge space 55 formed between the voltage application electrode 52 and the ground electrode 53 is converted into a plasma generation space. The treatment (for example, surface wettability imparting, etc.) is performed by guiding to the surface of a substrate (indicated by a two-dot chain line) 60, which is an object to be treated, disposed outside (in this example, below the counter electrode). I have.
[0044]
That is, the processing gas is introduced into the discharge spaces 54 and 55 from the slit-like processing gas introduction ports 56 and 57 formed in the housing 40 above the discharge spaces 54 and 55, and is not shown in the discharge spaces 54 and 55. When an electric field is applied to the electrode from a power supply, the electrode is turned into plasma, and is blown toward the base material 60 from the slit-shaped plasma outlets 54a and 55a.
[0045]
Cooling water channels 58a and 58b are formed in the voltage application electrode 52 and the ground electrodes 51 and 53, respectively. In the present embodiment, cooling water is introduced from the cooling water channel 58a and discharged from the cooling water channel 58b. It is supposed to.
[0046]
In the present embodiment, the ground electrodes 51 and 53 are arranged on both left and right sides of the voltage application electrode 52 so as to face each other. However, a pair of counter electrode structures (for example, the voltage application electrode 52 and the ground electrode 51 or the voltage (A combination of the electrode 52 and the ground electrode 53).
[0047]
Next, a remote gas supply device according to the present embodiment will be described.
[0048]
The remote type gas supply device 1 according to the present embodiment has a structure in which a processing gas supplied from a gas supply source (not shown) is introduced from a processing gas supply port 10 and guided to processing gas introduction ports 56 and 57 of a remote electrode. Has become.
[0049]
That is, a first container 11 connected to the processing gas supply port 10, a second container 12 provided so as to include the entire first container 11, and a slit-shaped gas communication passage 14 with the second container 12. , 14 and a third container 13 disposed adjacent to the processing gas inlets 56 and 57 of the remote type electrode.
[0050]
The first container 11 is mainly formed in a hollow cylindrical body 21 as shown in FIG. 5, and the base end side of the cylindrical body 21 is connected to the processing gas supply port 10. The end 23 opposite to the connecting portion 22 is closed. On the outer peripheral surface of the cylindrical body 21, gas blowing holes 24, 24... Are uniformly formed at four places (or eight places) along the circumferential direction. The holes 24 are formed at predetermined intervals (pitch) P along the longitudinal direction. In the present embodiment, the interval (pitch) P between the gas blowing holes 24, 24,... Formed along the longitudinal direction is formed so as to gradually decrease from the connecting portion 22 side toward the end portion 23 side. Have been. Specifically, when the length of the cylindrical body 21 is 250 mm, the outer diameter is 16 mm, the inner diameter is 13 mm, and the diameter of the gas blowing hole 24 is 0.5 mm, for example, the pitch P1 is 12 mm near the connecting portion 22 and the center is The pitch P is linearly shortened so that the pitch P2 is 10 mm in the portion and the pitch P3 is 8 mm near the end 23. However, instead of being linear, it may be formed so as to be gradually shortened (that is, so that the interval is gradually increased from sparse to dense).
[0051]
Since the pressure at the end 23 is high, the interval near the end 23 may be reduced again. That is, even if the gap is formed to be sparse, dense, and sparse from the connecting portion 22 toward the end portion 23, the processing gas can be uniformly blown out from each of the gas blowing holes 24, 24. It is.
[0052]
The second container 12 is formed in a box-like hollow body having a rectangular cross section provided so as to include the entire first container 11 of the cylindrical body 21, and has a volume at least equal to that of the first container 11. It is 5 times or more, for example, about 5 to 20 times. The second container 12 has a function as a buffer for lowering the pressure of the processing gas blown out of the first container 11, and the dynamic pressure decreases as the processing gas spreads in the container, thereby reducing the flow of the processing gas. Plays a role in reducing the effects of Therefore, in order to sufficiently fulfill the function as a buffer, the volume of the first container 11 must be at least five times or more. On the other hand, even if it is 20 times or more, the function as a buffer hardly changes. Therefore, considering the miniaturization of the device, up to about 20 times is sufficient.
[0053]
Further, the partition plate 15 which is the bottom surface of the second container 12 and also the upper surface of the third container 13 has slit-shaped gas communication passages 14 and 14 formed on both left and right sides thereof in parallel. The processing gas, which has been substantially in a static pressure state in the second container 12, is introduced into the third container 13 through the gas communication passages 14, 14. In this case, the slit width t2 of the gas communication passage 14 is formed to be equal to or slightly wider than the width t1 of the discharge spaces 54 and 55 of the remote electrode. By setting the width in this manner, the introduction of the processing gas from the second container 12 to the third container 13 is performed smoothly.
[0054]
The third container 13, like the second container 12, is formed in a box-shaped hollow body having a rectangular cross section, and is set to have the same volume as or smaller than the volume of the second container 12. The width of the processing gas inlets 56 and 57 of the remote type electrode opened on the bottom surface of the second container 12 is from the upper side opening in the third container 13 to the lower side reaching between the opposing electrodes of the remote type electrode. It is formed in a funnel shape that gradually reduces in size. Accordingly, the flow of the processing gas introduced from the third container 13 into the discharge spaces 54 and 55 between the opposing electrodes of the remote electrode becomes smoother, and the flow velocity can be made uniform.
[0055]
【The invention's effect】
As described above, according to the present invention, the first container is formed as a hollow cylinder whose end opposite to the connection portion of the processing gas supply port is closed, and is formed in the longitudinal direction of the cylinder. Gas blowing holes are formed at predetermined intervals along the gap. Further, the gap between the gas blowing holes is formed so as to gradually decrease from the connecting portion side to the end portion side. Thereby, a processing gas with a uniform flow rate can be blown into the second container from each gas blowing hole of the first container. Further, since the volume of the second container is at least five times the volume of the first container, the second container has a sufficient function as a buffer for lowering the pressure of the processing gas blown out of the first container. Can be expressed. That is, as the processing gas spreads in the container, the dynamic pressure decreases, and the influence of the flow of the processing gas can be reduced. Further, since the width of the slit formed in the second container is formed to be equal to or larger than the width between the counter electrodes of the remote type electrodes, the processing gas can be smoothly introduced from the second container to the third container. Can be. Further, the volume of the third container is set to be equal to or smaller than the volume of the second container, and the width of the processing gas inlet of the remote electrode formed in a slit shape is set to the upper side opening into the third container. Since it is formed so as to gradually reduce toward the lower side reaching between the opposing electrodes of the remote type electrode, the flow of the processing gas introduced from the third container between the opposing electrodes of the remote type electrode is more smoothly and The flow rate can be made uniform.
[Brief description of the drawings]
FIG. 1 is a plan view showing a partial cross section of an entire remote type electrode including a remote type gas supply device of the present invention.
FIG. 2 is a side view showing a partial cross section of the entire remote electrode including the remote gas supply device of the present invention.
FIG. 3 is a bottom view showing a partial cross section of the entire remote electrode including the remote gas supply device of the present invention.
FIG. 4 is a cross-sectional view of the entire remote-type electrode including the remote-type gas supply device of the present invention as viewed from the side.
FIG. 5 is a side view showing an appearance of a first container according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Remote type gas supply apparatus 10 Processing gas supply port 11 First container 12 Second container 13 Third container 14 Gas communication passage 15 Partition plate 21 Cylindrical body 22 Connecting part 23 End part 24 Gas blowing hole 40 Housing 51, 53 Ground Electrodes 52 Voltage application electrodes 54, 55 Discharge spaces 54a, 55b Plasma outlets 56, 57 Processing gas inlets 58a, 58b Cooling water channel 60 Base material

Claims (5)

In a remote gas supply device for guiding a processing gas introduced from a processing gas supply port to a processing gas introduction port of a remote electrode,
A first container connected to the processing gas supply port, a second container provided so as to include the entire first container, and a remote container that is provided adjacent to the second container via a gas communication passage and is adjacent to the second container. A third container connected to the processing gas inlet of the mold electrode,
The first container is formed in a hollow cylindrical body having an end opposite to the connecting portion of the processing gas supply port closed, and has gas blowing holes at predetermined intervals along a longitudinal direction of the cylindrical body. A remote type gas supply device characterized by being formed. The remote type gas supply device according to claim 1, wherein an interval between the gas blowing holes is formed so as to gradually decrease from a connecting portion side to an end portion side. 3. The remote gas supply device according to claim 1, wherein the volume of the second container is at least five times the volume of the first container. 4. The width of the gas communication passage formed in the second container is formed to be equal to or wider than the width between the counter electrodes of the remote electrode. 3. The remote gas supply device according to 1. The volume of the third container is set to be equal to or smaller than the volume of the second container, and the width of the processing gas introduction port of the remote electrode formed in a slit shape is set in the third container. The remote type gas according to any one of claims 1 to 4, wherein the remote type gas is formed so as to gradually decrease from an upper side where the opening is formed to a lower side extending between the opposing electrodes of the remote type electrode. Feeding device.

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