JP2023062318A - Dielectric barrier discharge type plasma generator - Google Patents

Abstract

To provide a dielectric barrier discharge type plasma generator with which it is possible to effectively spray plasma evenly from all regions of a discharge port.SOLUTION: A dielectric barrier discharge type plasma generator comprises: a dielectric substrate that exhibits a planar shape extending in a first direction; a first electrode which is placed contacting a face of the dielectric substrate; a second electrode which is placed, being separated from the dielectric substrate, on the side opposite the side where the first electrode is placed, regarding a second direction which is orthogonal to the first direction; a gas passage formed by a clearance between the dielectric substrate and the second electrode, in which a gas flows in a third direction that is orthogonal to the first and second directions; and a discharge port which is provided at an edge of the gas passage and extends in the first direction. One of the dielectric substrate and the second electrode is placed so as to sandwich the other of the dielectric substrate and the second electrode in the second direction via the clearance.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dielectric barrier discharge plasma generator.

Plasma generators are used in manufacturing processes for plastics, paper, fibers, semiconductors, liquid crystals, films, and the like. For example, by irradiating the object to be treated with plasma from a plasma generator, surface treatment for improving the hydrophilicity, adhesiveness, or print adhesion of the surface of the object to be treated, organic matter is removed and washed, or an oxide film is formed on the surface of the object to be treated.

FIG. 16 is a cross-sectional view schematically showing a conventional plasma generator. In Patent Document 1, as shown in FIG. 16, a pair of electrodes (201, 201) facing each other are provided, and the facing surfaces (202, 202) of the respective electrodes are moved toward each other as the workpiece 240 is approached. A plasma generator 200 is disclosed that is tilted for a narrower separation. That is, they are arranged so that the distance between the pair of facing surfaces (202, 202) narrows as the lower surface opening 226 is approached.

The plasma generator 200 applies a voltage between the pair of electrodes (201, 201) while introducing the plasma source gas Gc from the upper surface opening 223, so that the region (discharge voltage) sandwiched between the pair of opposing surfaces (202, 202) is generated. A large number of streamer discharges Sd are generated in the region 207). A plasma source gas Gc is introduced into the discharge region 207 from the upper opening 223 through the orifice 225 of the jet plate 224 . Therefore, the plasma source gas Gc is accelerated by the orifice 225 and jetted to the discharge region 207 at high speed. This injection causes a turbulent flow of the plasma source gas Gc, and the streamer discharge Sd is dispersed within the discharge region 207 .

Thereafter, plasma Pc is generated substantially uniformly over the entire discharge region 207 by the distributed streamer discharge Sd. The generated plasma Pc is injected as a plasma jet into the processing space 205 through the lower surface opening 226 of the discharge region 207 and sprayed onto the object 240 to be processed. Patent Document 1 describes that uniform plasma can be generated by adopting the above configuration.

The top surfaces of the electrodes (201, 201) and the facing surfaces (202, 202) are covered with a dielectric 203. As shown in FIG. The thickness of the coating of dielectric 203 is constant throughout, eg, 0.5 mm to 5 mm.

Another known method is a device that generates plasma by inputting microwaves between a microstrip line and a ground conductor (see Patent Document 2). According to this device, impedance matching is performed by adjusting the thickness of the dielectric layer by giving it a slope.

JP 2010-009890 A JP 2008-282784 A

The plasma generator 200 disclosed in Patent Document 1 aims to generate plasma Pc substantially uniformly over the entire discharge region 207 by generating turbulent flow. However, for example, the plasma Pc generated at a position far from the bottom opening 226 within the discharge region 207 disappears while moving toward the bottom opening 226 . Therefore, when the electrodes (201, 201) are arranged in the manner shown in FIG. I can't. This causes unevenness in the degree of processing on the surface of the object 240 to be processed.

The plasma generator disclosed in Patent Document 2 is a technology that uses microwaves. Plasma generated by microwaves is generated at a high density in the antinode portion of the standing wave where the electric field strength is strong. Standing waves are generated not only in the microwave input direction, but also in the direction perpendicular to the input direction. will do. Therefore, it is not easy to uniformly jet the plasma from the entire area of the outlet in the microwave-generated plasma.

Furthermore, from the viewpoint of generating a standing wave, the device itself cannot be lengthened in the first place. For this reason, for example, even if it is intended to be used for surface treatment of an object to be treated, the treatment capability is extremely low, and its application is practically difficult.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a dielectric barrier discharge plasma generator capable of efficiently and uniformly injecting plasma from the entire area of the outlet.

In the dielectric barrier discharge plasma generator of the present invention,
a plate-shaped dielectric substrate extending in a first direction;
a first electrode arranged in contact with the surface of the dielectric substrate;
With respect to a second direction orthogonal to the first direction, a second electrode extending in the first direction is spaced apart from the dielectric substrate on the side opposite to the side on which the first electrode is disposed. two electrodes;
a gas flow path formed by a gap between the dielectric substrate and the second electrode, through which gas flows in a third direction orthogonal to the first direction and the second direction;
an outlet provided at one end of the gas channel in the third direction and extending in the first direction;
When viewed in the first direction, at least one of the dielectric substrate, the first electrode, and the second electrode extends from a predetermined location to the outlet in the third direction. having an inclined surface,
One of the dielectric substrate and the second electrode is arranged so as to sandwich the other of the dielectric substrate and the second electrode in the second direction with the gap interposed therebetween. and

According to the above configuration, the gas flows in the third direction toward the outlet in the gas flow path formed by the gap provided between the dielectric substrate and the second electrode in the second direction. Since both the dielectric substrate and the second electrode extend in the first direction, this gap or gas channel also extends in the first direction. Therefore, the gas moves in the third direction toward the blowout port in the gas flow path extending in the first direction, and the slit-shaped gas is discharged from the blowout port.

A gas flow path is formed by a gap sandwiched between the dielectric substrate and the second electrode. Then, when viewed in the first direction, at least one of the dielectric substrate, the first electrode, and the second electrode has an inclined surface in a region between a predetermined location and the outlet in the third direction. have. As a result, when a voltage is applied between the first electrode and the second electrode, the electric field monotonously changes in the gap, that is, in the gas flow path, as the air outlet is approached. Such a configuration can be realized, for example, by changing the thickness of the dielectric substrate, the thickness of the first electrode, or the thickness of the second electrode as it approaches the outlet in the third direction. As a typical example, with respect to the third direction, the width of the gas flow path (the length in the second direction) is narrowed as it approaches the blowout port. The electric field applied to the gas flowing therein is enhanced.

According to the above configuration, an extremely high-intensity electric field is formed near the outlet, and plasma is generated intensively in this region. As a result, the plasma-containing gas can be discharged from the entire area of the air outlets in the first direction. Therefore, the plasma-containing gas can be efficiently blown from the outlet to the object to be processed, and the object to be processed can be efficiently processed.

In order to discharge the plasma-containing gas from the outlet, it is necessary to generate an extremely high electric field particularly in the vicinity of the outlet. Therefore, the flow channel width (the length in the second direction) of the gas flow channel must be naturally designed to be narrow. Therefore, the plasma-containing gas blown out from the blowout port extending in the first direction has an extremely thin sheet shape.

When such a sheet-shaped plasma-containing gas is sprayed onto an object to be processed in order to perform surface treatment on the object, the area of the surface of the object to be processed that can be processed per unit time is limited. Become. However, as described above, the width of the gas flow path cannot be increased in order to increase the processing efficiency. This is because there is a risk that the efficiency of plasma generation will be reduced, or that plasma will not be generated in the first place.

As a method of increasing the area of the object to be processed that can be processed per unit time, a method of arranging a plurality of dielectric barrier discharge plasma generators in the second direction is conceivable. However, in this case, the distance between the blow-out ports of the adjacent dielectric barrier discharge plasma generators widens, and the object to be processed is processed at a portion facing the blow-out ports and at a portion sandwiched between the blow-out ports. difference in the degree of In addition, outside air is likely to flow into the portion sandwiched between the outlets. Under these circumstances, it is necessary to spend a certain amount of processing time in order to perform surface treatment on the object to be processed to a desired degree.

On the other hand, according to the above configuration, one of the dielectric substrate and the second electrode is arranged so as to sandwich the other of the dielectric substrate and the second electrode with the gap in the second direction. ing. As a result, gas flow paths formed by the gaps are formed at a plurality of positions spaced apart with respect to the second direction. In other words, in the case of this device, even though it is a single device, the plasma-containing gas flows from the plurality of gas flow passages from the blow-out port by causing the gas to flow through the plurality of gas flow passages toward the blowout port. Ejected. Further, the intervals between these gas flow paths are extremely narrow compared to the case where a plurality of devices are simply arranged.

When the plasma-containing gas is blown onto the object to be processed for surface treatment of the object, the object to be processed is arranged very close to the outlet. For this reason, the plasma-containing gas blown out from the plurality of gas flow paths is blown onto the surface of the object to be processed, and the difference in the flow speeds blown out from both gas flow paths and the air currents reflected on the surface of the object to be processed cause Originatingly, an airflow is also generated in the space sandwiched between the two gas flow paths. As described above, the spacing between adjacent gas passages in the second direction is much narrower than the spacing between adjacent outlets when a plurality of devices are arranged side by side in the second direction. As a result, the plasma-containing gas flows into the space sandwiched between the adjacent gas flow paths, and as a result, the plasma-containing gas can be blown out with a width larger than the width of the blow-out port. Therefore, the surface treatment speed of the object to be treated can be increased more than conventionally.

Furthermore, the above apparatus does not use microwaves because it uses a dielectric barrier discharge to generate the plasma. Therefore, since there is no need to perform impedance matching or the like for microwave transmission, the shapes of the dielectric substrate, electrodes, and outlets are not particularly limited. In addition, since the above apparatus does not use microwaves, it does not require measures against leakage of electromagnetic waves.

The outlet may be provided for each gas flow path, or a common outlet connected to each gas flow path may be provided. In the former case, the plasma-containing gas that has flowed through each gas flow path is blown out from each outlet. In the latter case, the end of each gas flow channel in the third direction is located at a position slightly retracted in the third direction from the blow-out port, and the gas flowing through each gas flow channel flows from the common blow-out port. blown out. The minute distance referred to here is, for example, a distance of about 0.5 to 2 times the thickness of the dielectric substrate.

The gas flow path is formed at two locations spaced apart in the second direction,
The outlets may be arranged corresponding to the respective gas flow paths.

The gas flow paths may be formed at two locations spaced apart in the second direction, and may be connected to each other at the end portion on the outlet side.

A main material of the dielectric substrate may be aluminum oxide (Al ₂ O ₃ ) or aluminum nitride (AlN). Here, the term "main material" refers to a component that accounts for 80% or more of the component when the constituent material is analyzed.

Aluminum oxide and aluminum nitride have relatively low dielectric constants and relatively high physical strength and hardness. Therefore, by using aluminum oxide or aluminum nitride as the main material of the dielectric substrate, it is possible to increase the amount of plasma generated per unit power and to reduce the risk of breakage even if the dielectric substrate is made thinner.

Among them, aluminum nitride has good thermal conductivity and can efficiently dissipate the heat of the dielectric substrate. As a result, of the first electrode and the second electrode, the temperature rise of the electrode on the side to which the high voltage is applied (high voltage side electrode) can be suppressed, so the stress at the interface due to the thermal expansion of aluminum nitride and the high voltage side electrode can be suppressed. can be reduced. As a result, the life of the dielectric barrier discharge plasma generator can be extended.

The dielectric substrate has a slit-shaped hole extending parallel to the main surface,
the first electrode has a plate shape and is embedded in the hole to be in contact with the dielectric substrate;
The second electrodes may be arranged so as to sandwich the dielectric substrate with a space from both sides in the first direction.

In this case, preferably, the first electrode is a high voltage side electrode and the second electrode is a low voltage side electrode. With such a configuration, the electrode located outside the device becomes the electrode on the low voltage side, which contributes to the safety of the operator.

The dielectric barrier discharge plasma generator further comprises
a gas buffer substrate in contact with the pair of second electrodes from the outside at peripheral edge portions;
a gas delivery device for introducing the gas into a gap sandwiched between the gas buffer substrate and the second electrode;
At a plurality of locations in the first direction, communication holes penetrating the second electrode in the second direction may be provided.

According to the above configuration, the gas introduced from the gas delivery device is stored in the gap between the gas buffer substrate and the second electrode, and then flows into the gas flow path through the plurality of communication holes. As a result, the gas that has flowed into the gas flow path can be uniformly discharged from the outlet without disturbing the flow of the gas.

In particular, by providing communication holes at a plurality of locations in the first direction, gas is introduced into the gas flow path from a plurality of different locations in the first direction. This makes it easy to laminarize the gas flowing through the gas flow path.

a pair of the dielectric substrates are spaced apart in the second direction,
a pair of the first electrodes disposed on respective outer surfaces of the pair of dielectric substrates;
The second electrode may be arranged at a position spaced apart in the second direction from the inner surfaces of the pair of dielectric substrates.

In this case, the first electrode may be a metal foil. The metal material is not limited, but is preferably a highly conductive material, typically one or more materials belonging to the group consisting of copper, silver, aluminum, and gold, or compounds of said materials.

The first electrode may be a sintered body containing metal. Since the metal-containing sintered body can be printed with a metal paste to form an electrode, there is no need to use an adhesive when forming the first electrode on the dielectric substrate.

The first electrode may be formed by plating, vapor deposition, sputtering, or thermal spraying. In the case of this structure, similarly, it is not necessary to use an adhesive when forming the first electrode on the dielectric substrate.

It is preferable that the end portion of the first electrode on the side of the blowout port is arranged to retreat from the blowout port in the third direction.

If the first electrode were to extend to the position of the outlet in the third direction, there would be a risk of direct discharge between the first electrode and the second electrode without passing through the dielectric substrate. When such a discharge occurs, the first electrode, the dielectric substrate, or the second electrode are damaged, and the materials constituting these members are mixed into the plasma-containing gas as impurities.

From the viewpoint of discharge efficiency, it is advantageous to arrange the end of the first electrode so as to coincide with the end of the outlet in the third direction. However, in such an arrangement mode, creeping discharge may occur on the dielectric substrate due to the above circumstances. Once this creeping discharge occurs, the direct discharge becomes dominant instead of the dielectric barrier discharge, causing an excessive discharge current to flow, leading to damage to the electrodes and, in turn, damage to the power supply device.

On the other hand, by adopting the configuration as described above, the direct discharge between the first electrode and the second electrode is suppressed. It is possible to prevent the contamination of impurities.

The dielectric barrier discharge plasma generator may include a power supply connected to the first electrode. The power supply device is preferably configured to supply a voltage signal having a voltage of 3 kV to 20 kV and a frequency of 20 kHz to 150 kHz to the first electrode.

Plasma can be favorably generated by the dielectric barrier discharge method when the power supply device as described above is provided. The reason for setting the upper limit to 150 kHz is that the wavelength takes into account the plasma irradiation length and that the frequency detected by the noise terminal voltage in the EMC standard is higher than 150 kHz.

A light shielding member may be provided on the outer side of the outlet in the third direction. By providing the light shielding member at the air outlet, it is possible to suppress the light generated by the discharge from irradiating the object to be processed.

The dielectric barrier discharge plasma generator may further include a starting assisting member arranged on the surface of the dielectric substrate on the side of the gas flow path. It is preferable that the start-up assisting member is arranged very close to the outlet. However, if the position of the starting assisting member and the position of the outlet are aligned when viewed in the first direction, part of the plasma-containing gas from the blowing outlet collides with the starting assisting member, resulting in starting. Auxiliary members may be worn or removed. On the other hand, if the starting assist member is too far from the outlet in the third direction, it will not function as a starting assist. From this point of view, it is preferable that the start-up assisting member is arranged in the vicinity of the blower outlet and at a position slightly retracted from the blower outlet in the third direction. Preferably, the setback distance is less than 10 mm.

A dielectric barrier discharge requires high power at the time of starting (at the start of discharge). Under these circumstances, preferably high power is applied at start-up. However, such a method requires a large-sized power supply device compatible with high power and a trigger electrode arranged near the discharge space, which may lead to an increase in the scale of the entire device.

At the start of a plasma discharge, the presence of initial electrons is required at the point where the plasma is to be generated. Therefore, by arranging the start assisting member as described above, the initial electrons are supplied into the gas flow path near the outlet at the initial stage of start. This eliminates the need for a large power supply, trigger electrode, etc., and provides a compact and inexpensive plasma generator.

According to the dielectric barrier discharge plasma generator of the present invention, it is possible to efficiently and uniformly inject plasma from the entire area of the outlet.

1 is a perspective view schematically showing the configuration of a first embodiment of a dielectric barrier discharge plasma generator; FIG. 2 is a schematic cross-sectional view of the plasma generator shown in FIG. 1 taken along line II-II. FIG. 2 is a schematic cross-sectional view of the plasma generator shown in FIG. 1 taken along line III-III. FIG. FIG. 3 is a schematic cross-sectional view showing only a dielectric substrate extracted from FIG. 2; FIG. 3 is a schematic cross-sectional view showing only the first electrode extracted from FIG. 2; FIG. 4 is a schematic plan view of the second electrode facing the -Z side surface of the dielectric substrate in the Z direction when viewed from the +Z side. FIG. 3 is a cross-sectional view showing the first electrode, the second electrode, and the dielectric substrate extracted from FIG. 2 and showing an enlarged view of the vicinity of the first end; FIG. 8 is a partially enlarged view of FIG. 7; FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 4 is a partially enlarged cross-sectional view schematically showing a modification of the first embodiment of the dielectric barrier discharge plasma generator. FIG. 2 is a perspective view schematically showing the configuration of a second embodiment of a dielectric barrier discharge plasma generator. FIG. 11 is a schematic cross-sectional view of the plasma generator shown in FIG. 10 taken along line XI-XI; 11 is a schematic cross-sectional view of the plasma generator shown in FIG. 10 taken along line XII-XII. FIG. FIG. 12 is a cross-sectional view showing the first electrode, the second electrode, and the dielectric substrate extracted from FIG. 11 and enlarging the vicinity of the first end; FIG. 14 is a partially enlarged view of FIG. 13; FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. FIG. 5 is a partially enlarged cross-sectional view schematically showing a modification of the second embodiment of the dielectric barrier discharge plasma generator. 1 is a cross-sectional view schematically showing a conventional dielectric barrier discharge plasma generator; FIG.

An embodiment of a dielectric barrier discharge plasma generator according to the present invention will be described with reference to the drawings as appropriate. The drawings below are schematic representations, and the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios. Moreover, there are cases where the dimensional ratios do not match between the drawings.

[First embodiment]
A first embodiment of a dielectric barrier discharge plasma generator will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing a dielectric barrier discharge plasma generator 1 (hereinafter abbreviated as "plasma generator 1") of the present embodiment. FIG. 2 is a schematic cross-sectional view of the plasma generator 1 in FIG. 1 taken along line II-II. Moreover, FIG. 3 is a schematic cross-sectional view of the plasma generator 1 in FIG. 1 taken along line III-III. 2 also shows the gas delivery device 61, which is omitted in FIG. 1 for convenience of explanation.

The plasma generator 1 includes a first electrode 10 (see FIG. 2), a second electrode 20, and a dielectric substrate 30. As shown in FIG. Although the plasma generator 1 shown in FIGS. 1 to 3 further includes a gas buffer substrate 40, it is optional whether the plasma generator 1 includes the gas buffer substrate 40 or not.

The plasma generator 1 is a device that internally generates gas containing plasma (hereinafter referred to as "plasma gas G1"). The plasma generator 1 has an outlet 5 for blowing out the plasma gas G1. As shown in FIG. 1, the outlet 5 extends in the Y direction and has a substantially rectangular shape when viewed in the X direction. A direction orthogonal to the X direction and the Y direction is defined as the Z direction. In the following description, the XYZ coordinate system attached to FIG. 1 will be referred to as appropriate.

In the following description, when distinguishing between positive and negative directions when expressing directions, positive and negative signs are added, such as “+X direction” and “−X direction”. Moreover, when expressing a direction without distinguishing between positive and negative directions, it is simply described as “X direction”. That is, in the present specification, the term “X direction” includes both “+X direction” and “−X direction”. The same applies to the Y direction and Z direction.

In this specification, the Y direction corresponds to the "first direction", the Z direction corresponds to the "second direction", and the X direction corresponds to the "third direction".

As shown in FIG. 1, the plasma generator 1 of the present embodiment includes blow-out ports 5 at two locations spaced apart in the Z direction. That is, the plasma gas G1 is blown out from these outlets 5. As shown in FIG. Each air outlet 5 is formed at a spaced portion between the dielectric substrate 30 and the second electrode 20 in the Z direction.

(Dielectric substrate 30)
As shown in FIGS. 1 to 3, the dielectric substrate 30 is a plate member extending in the Y direction. In the present embodiment, at least a portion of the first electrode 10 is embedded inside the dielectric substrate 30 , so that the dielectric substrate 30 and the first electrode 10 are in contact with each other.

FIG. 4 is a schematic cross-sectional view showing only the dielectric substrate 30 extracted from FIG. FIG. 5 is a schematic cross-sectional view showing only the first electrode 10 extracted from FIG.

As shown in FIG. 4, the dielectric substrate 30 has holes 38 extending in the X direction. The hole 38 is formed extending in the Y direction. That is, the dielectric substrate 30 has slit-shaped holes 38 . The first electrode 10 schematically shown in FIG. 5 is embedded in the slit-shaped hole 38 . Although the first electrode 10 is completely housed in the hole 38 in the example of FIG. 2, it may partly protrude from the hole 38 in the -X direction. However, as will be described later, in this embodiment, the first electrode 10 constitutes an electrode on the high voltage side, so from the viewpoint of safety, the end (end face) on the -X side of the first electrode 10 should be a dielectric It is preferably located on the +X side of the -X side end (end surface) of the body substrate 30 .

In the examples shown in FIGS. 2 and 4, a structure is employed in which the length of the dielectric substrate 30 in the Z direction (hereinafter referred to as "thickness") becomes thinner as it approaches the outlet 5 in the X direction. However, this structure is only an example.

The dielectric substrate 30 is preferably made of a material with a low dielectric constant from the viewpoint of increasing the amount of plasma generated per unit power. It is preferable that the dielectric constant value of the material is 10 or less. The dielectric constant of the material is preferably as low as possible, but can be typically 4-10.

Although the material of the dielectric substrate 30 is not particularly limited, it is preferable that the dielectric constant is as low as possible as described above. Furthermore, from the viewpoint of durability, the material is preferably ceramics. Examples of ceramics include aluminum oxide, aluminum nitride, steatite, and the like. These materials have relatively low dielectric constants, relatively high strength, and excellent durability. Therefore, if the dielectric substrate 30 is made of aluminum oxide, aluminum nitride, or steatite, the amount of plasma generated per unit power can be increased. Moreover, since the durability is excellent, even if the thickness of the dielectric substrate 30 is reduced, there is little risk of breakage.

In order to realize the plasma generator 1 having the shape shown in FIG. A method can be adopted in which the first electrode 10 is fitted in a paste-applied state, and the two are tightly fixed.

The dielectric substrate 30 may contain the above-described material as a base material and a substance that assists electron generation. Examples of the substance that assists electron generation include silver, platinum, copper, carbon, and transition metal compounds. Initial electrons are generated by applying an electric field to the substance that assists electron generation, and are emitted into a discharge space (a gas flow path 3 described later). Therefore, by configuring the dielectric substrate 30 as described above, it is possible to work the startability advantageously.

The content of the substance that assists electron generation is preferably 1 part by mass or less with respect to the entire dielectric substrate 30 (when the dielectric substrate 30 is 100 parts by mass). If the content of this substance is too large, there is a concern that the substance evaporates and scatters with the discharge, mixes with the plasma gas G1, and is sprayed onto the object to be processed, which is the object to be irradiated with the plasma gas G1. From the viewpoint of sufficiently exhibiting the effect of improving startability, the content of the substance is preferably set to 0.05 parts by mass or more experimentally.

(First electrode 10)
As described above with reference to FIG. 2, in the plasma generator 1 of the present embodiment, at least a portion of the first electrode 10 is embedded in the dielectric substrate 30 in close contact therewith. That is, the first electrode 10 is arranged in contact with the surface of the dielectric substrate 30 . Note that FIG. 2 shows an example in which the entire first electrode 10 is embedded in the dielectric substrate 30 .

In the plasma generator 1, a voltage is applied between the first electrode 10 and a second electrode 20, which will be described later, via the dielectric substrate 30 and the gas channel 3, so that the gas flows through the gas channel 3. The gas is turned into plasma to generate plasma gas G1. Therefore, one of the first electrode 10 and the second electrode 20 is a high-voltage electrode, and the other is a low-voltage electrode. In the following embodiments, the first electrode 10 is the electrode on the high voltage side, and the second electrode 20 is the electrode on the low voltage side, but they may be reversed. However, in the plasma generator 1 of the present embodiment, from the viewpoint of safety, the second electrode 20, which is exposed to the outside and is located near the operator, is the electrode on the low voltage side, and is buried inside. It is preferable to use the first electrode 10 on the high voltage side as the first electrode 10 .

As shown in FIGS. 1 and 3, in the present embodiment, the length of the first electrode 10 in the Y direction (hereinafter referred to as "width") does not completely match the width of the dielectric substrate 30. , are of approximately equal length. From the viewpoint of ejecting the plasma gas G1 from the outlet 5 in a wide area (into a long area in the Y direction), it is preferable to form the first electrode 10 as wide as possible. However, the invention is not limited to the width of the first electrode 10 .

In this embodiment, the first electrode 10 is slightly retreated to the -X side of the blower outlet 5 in the X direction (see FIG. 2). Referring to FIG. 2, the +X side end 10a of the first electrode 10 is slightly receded to the -X side from the end related to the outlet 5 side (+X side) of the plasma generator 1 . For convenience, the end related to the blowout port 5 side (+X side) of the plasma generator 1 is referred to as "first end 71", and the end related to the side opposite to the blowout port 5 (−X side) is referred to as "second end 71". It may be referred to as "two ends 72".

In the vicinity of the air outlet 5 , there is a risk of direct discharge between the first electrode 10 and the second electrode 20 without passing through the dielectric substrate 30 . When such a discharge occurs, the electrodes (10, 20) or the dielectric substrate 30 are damaged, and these constituent materials are mixed into the plasma gas G1 as impurities.

From the viewpoint of discharge efficiency, it is preferable to bring the +X-side end 10a of the first electrode 10 as close to the outlet 5 as possible, that is, to substantially match the first end 71 . However, if such a configuration is adopted, the risk of creeping discharge occurring between the first electrode 10 and the second electrode 20 increases, and direct discharge rather than dielectric barrier discharge becomes dominant. Therefore, as described above, the configuration is adopted in which the +X side end portion 10a of the first electrode 10 is slightly retracted from the first end 71 toward the -X side (second end 72 side). This receding distance, that is, the distance between the +X side end 10a of the first electrode 10 and the first end 71 is typically 1 mm to 5 mm.

The material of the first electrode 10 is not particularly limited, but preferably has high conductivity. is a compound.

It is preferable that the first electrode 10 and the dielectric substrate 30 are in close contact with each other and that there is no air layer at the interface between the two. This is because if there is a layer of air, discharge may occur inside the space, and the generated radicals may deteriorate the first electrode 10 . For this reason, it is preferable that the first electrode 10 and the dielectric substrate 30 are in close contact with each other within the range of the μm order. From the viewpoint of enhancing the adhesion between the two, the surface of the dielectric substrate 30 may be roughened to form fine irregularities, aiming at an anchor effect. In particular, when the dielectric substrate 30 is cut to form the hole 38, the inner surface of the hole 38 is likely to have minute irregularities. Therefore, by subsequently fitting the first electrode 10 into the hole 38, the adhesion between the first electrode 10 and the dielectric substrate 30 is enhanced.

Typically, the thickness (the length in the Z direction) of first electrode 10 is thinner than the thickness of dielectric substrate 30 . In particular, by using the first electrode 10 as the electrode on the high voltage side, even if the material of the first electrode 10 expands with the application of high voltage, the thickness of the first electrode 10 is thin, so the influence of expansion becomes negligible for the dielectric substrate 30 .

When the first electrode 10 is the electrode on the high voltage side, the first electrode 10 is partially connected to the power supply 63 . A connection method between the power supply device 63 and the first electrode 10 is not particularly limited as long as it is electrically connected and can withstand the applied voltage. For example, connection by soldering and connection using various connectors (for example, coaxial connectors, etc.) can be mentioned. Since the plasma generator 1 of this embodiment does not use microwaves for plasma generation, it is not necessary to use a coaxial connector or coaxial cable having a predetermined characteristic impedance.

The voltage and frequency applied from the power supply device 63 to the first electrode 10 may be within a range in which dielectric barrier discharge can be generated in the plasma generator 1 . Typically, the applied voltage is between 3 kV and 20 kV, preferably between 3 kV and 10 kV. Also, the frequency of the voltage signal is typically 20 kHz to 1000 kHz, more preferably 50 kHz to 150 kHz. The reason why the upper limit is preferably 150 kHz is that the wavelength takes into consideration the plasma irradiation length and that the frequency detected by the noise terminal voltage in the EMC standard is higher than 150 kHz.

(Second electrode 20, gas flow path 3)
The second electrode 20 has a plate shape extending in the Y direction. More specifically, as shown in FIGS. 2 and 3, the second electrode 20 is arranged to sandwich the dielectric substrate 30 apart from both the +Z side and the −Z side. That is, the second electrode 20 is spaced apart from the dielectric substrate 30 on the side opposite to the side on which the first electrode 10 is arranged in the Z direction.

When the second electrode 20 is the electrode on the low voltage side, it may be connected to the ground potential directly or via a resistor, or may be connected to the output of the power supply device 63 on the low voltage side.

As shown in FIGS. 2 and 3, a concave portion 27 is formed in a part of the surface of the second electrode 20 on the side of the dielectric substrate 30 . The recess 27 is formed extending in the Y direction.

FIG. 6 is a schematic plan view of the second electrode 20 facing the −Z side surface of the dielectric substrate 30 in the Z direction when viewed from the +Z side. The second electrode 20 facing the +Z side surface of the dielectric substrate 30 in the Z direction may have substantially the same shape when viewed from the -Z side. In the following, for simplification of explanation, only the second electrode 20 located on the -Z side of the dielectric substrate 30 will be explained, and the explanation of the second electrode 20 located on the +Z side will be omitted.

2, 3, and 6, the second electrode 20 has a higher height at the outer edge 26 on the +Y side, the -Y side, and the -X side, and the recess 27 described above inside the outer edge 26. is formed. As shown in FIG. 2, the outer edge 26 of the second electrode 20 abuts the surface of the dielectric substrate 30 . That is, when the outer edge portion 26 of the second electrode 20 and the dielectric substrate 30 are brought into contact with each other, the concave portion 27 formed on the Z side of the second electrode 20 constitutes a gap. More specifically, for the second electrode 20 located on the −Z side of the dielectric substrate 30, the recess 27 formed on the +Z side of the second electrode 20 constitutes a gap. As for the second electrode 20 positioned on the +Z side, the recess 27 formed on the -Z side of the second electrode 20 constitutes a gap. A gap formed by these concave portions 27 constitutes the "gas flow path 3".

In the example shown in FIG. 6, communication holes 53 are formed at a plurality of positions spaced apart in the Y direction on the bottom surface of the recess 27 . Although the number of communication holes 53 is not particularly limited, it is preferably two or more as in this embodiment. The communication hole 53 is provided to guide the gas G0 (see FIG. 2) from the gas delivery device 61 to the gas flow path 3, as will be described later. By providing a plurality of communication holes 53 at different positions in the Y direction, it becomes easier to make the gas flow in the gas flow path 3 laminar. From the viewpoint of spreading the gas over a wide range in the Y direction when it is introduced into the gas flow path 3, it is preferable that the communication holes 53 are formed over a wide range in the Y direction.

FIG. 6 shows an example in which a plurality of independent communication holes 53 are formed. . However, "single" here means that each recess 27 is single. More specifically, a single communication hole 53 is formed in the recess 27 of the second electrode 20 located on the −Z side of the dielectric substrate 30, and the second electrode 20 located on the +Z side of the dielectric substrate 30. This means that another single communication hole 53 may be formed in the recess 27 of the .

(Gas buffer substrate 40)
As shown in FIGS. 1 to 3, the plasma generator 1 has a gas buffer substrate in contact with the second electrode 20 from the side opposite to the dielectric substrate 30, that is, from the outside in the ±Z direction. 40. In this embodiment, the gas buffer substrate 40 is in contact with the second electrode 20 at the peripheral portion. Therefore, a gap 51 is formed between the second electrode 20 and the gas buffer substrate 40 inside the peripheral portion.

A gas delivery device 61 (see FIG. 2) is connected to the air gap 51 . The gas G<b>0 delivered from the gas delivery device 61 is buffered in the gap 51 and then guided to the gas flow path 3 through the communication hole 53 . Although FIG. 2 shows a case in which a plurality of gas delivery devices 61 are provided, even if the gas G0 is delivered from the common gas delivery device 61 into each of the gaps 51, I do not care.

In the plasma generator 1 of this embodiment, the gas buffer substrate 40 is made of a conductive member such as metal.

(Blowout port 5)
The plasma generator 1 includes a blowout port 5 at the +X side end of the gas flow path 3 , that is, at the first end 71 . The blowout port 5 blows the plasma generated during the flow along the +X direction in the gas flow path 3 to the outside together with the gas flow (plasma gas G1). In the plasma generator 1, for example, the widths (lengths in the Y direction) of the gas flow path 3 and the outlet 5 are uniform regardless of the X coordinate. As a result, the plasma gas G1 can be uniformly jetted from the outlet 5 without disturbing the flow of the gas G0 that has flowed into the gas flow path 3 .

However, the present invention is not limited to this example, and the width of the outlet 5 may be adjusted as necessary. For example, the intensity of the plasma gas G1 can be increased by narrowing the width of the outlet 5 compared to the width of the −X side (second end 72 side) of the gas flow path 3 . Conversely, by widening the width of the outlet 5 compared to the width of the -X side (second end 72 side) of the gas flow path 3, the jet width of the plasma gas G1 can be widened, The range that can be sprayed at the same timing is expanded.

The gas delivered from the gas delivery device 61 may be one or more selected from the group consisting of He, Ne, and Ar as the starting gas for the plasma generator 1 . Further, as the gas after the plasma is generated, a gas capable of generating desired active species, specifically, one or more selected from the group consisting of hydrogen, oxygen, water, nitrogen and the like can be used.

In this embodiment, it is preferable that the gas flow through the gas flow path 3 is laminar. When the gas flow is laminar, the plasma can be jetted more homogeneously. Here, the Reynolds number is a parameter that distinguishes between laminar flow and turbulent flow.
The Reynolds number Re is given by ρ (kg/m ³ ) for the density of the fluid, U (m/s) for the flow velocity, L (m) for the characteristic length, and μ (Pa·s) for the viscosity coefficient of the fluid.
Re=ρ・U・L/μ
It is a dimensionless quantity represented by

The Reynolds number at the boundary between laminar flow and turbulent flow is called the critical Reynolds number, and its value is 2,000 to 4,000.

The size of the plasma generator 1 is not particularly limited.
As an example, the external dimensions are 750 mm in width (length in the Y direction), 40 mm in length (length in the X direction), and 20 mm in thickness (length in the Z direction, at the thickest point). be.
The outer dimensions of the dielectric substrate 30 are 750 mm in width, 40 mm in length, and 0.1 mm in thickness at the first end 71 .
The outer diameter dimensions of the first electrode 10 are 690 mm in width and 20 mm in length.
The external dimensions of the second electrode 20 are 750 mm in width and 20 mm in length. Also, the thickness of the first end 71 of the second electrode 20 is 0.1 mm on each of the +Z side and the −Z side.
The outer dimensions of the gas channel 3 are 700 mm in width and 35 mm in length on each of the +Z side and the -Z side.
The dimensions of the outlets 5 are 700 mm in width and 0.2 mm in height on the +Z side and -Z side, respectively. The outlet 5 positioned on the +Z side and the outlet 5 positioned on the -Z side are separated by a distance corresponding to the thickness of the first end 71 of the dielectric substrate 30 .

FIG. 7 is a cross-sectional view in which only the first electrode 10, the second electrode 20, and the dielectric substrate 30 are extracted from the plasma generator 1 shown in FIG. 2, and the vicinity of the first end 71 is enlarged and displayed. .

In the plasma generator 1 of the present embodiment, a part of the surface of the dielectric substrate 30 constitutes the inner surface of the gas channel 3, and the surface constituting the inner surface of the gas channel 3 has a first It includes a flat surface 31 substantially parallel to the XY plane at a position away from the end 71 in the -X direction, and an inclined surface 32 located on the +X side (first end 71 side) of the flat surface 31 .

The first electrode 10 embedded in the dielectric substrate 30 has a flat surface 11 substantially parallel to the XY plane at a position away from the first end 71 in the -X direction, and a +X side of the flat surface 11 ( and an inclined surface 12 located on the first end 71 side).

A part of the surface of the second electrode 20 arranged outside (±Z side) of the dielectric substrate 30 constitutes the inner surface of the gas flow channel 3. The surfaces include a flat surface 21 substantially parallel to the XY plane at a position away from the first end 71 in the -X direction, and an inclined surface 22 located on the +X side (first end 71 side) of the flat surface 21. and

In this manner, at least one surface of the dielectric substrate 30, the first electrode 10, and the second electrode 20 has an inclined surface at a position near the first end 71 in the X direction, that is, at a position near the air outlet 5. Thus, as the gas flows through the gas passage 3 and approaches the outlet 5, the intensity of the electric field applied to the gas is increased, and plasma is generated in the vicinity of the outlet 5 (plasma gas G1).

8 is a partially enlarged view of FIG. 7. FIG. In FIG. 8, for convenience of explanation, the workpiece W to be sprayed with the plasma gas G1 is also shown. In the example of FIG. 8, the plasma gas G1 is blown while the workpiece W moves in the Z direction.

According to the plasma generator 1 of this embodiment, the gas flow paths 3 are formed at a plurality of locations spaced apart in the Z direction. The gas flowing in the +X direction through these gas flow paths 3 is plasmatized in the vicinity of the first end 71 , and is sprayed onto the workpiece W from the outlet 5 as the plasma gas G<b>1 .

In this embodiment, the separation distance in the Z direction between the gas flow paths 3 at positions close to the first end 71 in the X direction is the thickness (Z direction length), ie the thickness of the edge 39 of the dielectric substrate 30 . In order to turn the flowing gas into plasma, it is necessary to apply a high electric field to the gas. From this point of view, the thickness of the dielectric substrate 30 has an upper limit. Although the thickness of the end portion 39 of the dielectric substrate 30 was 0.1 mm in the numerical example described above, the upper limit of the thickness of the end portion 39 is 1.0 mm. Although the lower limit of the thickness of the end portion 39 depends on the processing accuracy, it is practically 0.01 mm.

That is, according to the plasma generator 1 of the present embodiment, the plasma gas G1 is sprayed onto the workpiece W from a plurality of positions (a plurality of outlets 5) separated by a distance of less than 1.0 mm in the Z direction. . The object W to be treated is usually sprayed with the plasma gas G1 for the purpose of surface treatment. For this purpose, the workpiece W is arranged as close to the outlet 5 as possible. In reality, the separation distance (distance d0 in FIG. 8) between the object W to be processed and the outlet 5 is 1.0 mm to 5.0 mm. Therefore, when the plasma gas G1 jetted from the plurality of outlets 5 arranged in close proximity to each other in the Z direction collides with the surface of the object W, the turbulent flow caused by part of the reflection and the A slight difference in flow velocity of the plasma gas G1 causes a flow of the plasma gas G1 between them. As a result, a gas space PA filled with the plasma gas G1 is formed in a region wider than the opening width of each outlet 5 . Therefore, the surface treatment capability for the object W to be treated is improved.

As described above with reference to FIG. 2, when the gas delivery device 61 is provided for each gas flow path 3, the flow rate and flow velocity of the gas delivered from each gas delivery device 61 are slightly different. preferably controlled. Further, when the gas delivery device 61 is commonly used for a plurality of gas flow paths 3, the flow path width of the gas flow paths 3 may be slightly different from each other so that the gas flowing through each gas flow path 3 can be adjusted. are preferably designed so that the flow velocities of are different from each other.

In the plasma generator 1 of the present embodiment, at least one surface of the dielectric substrate 30, the first electrode 10, and the second electrode 20 is an inclined surface as described above, and is spaced apart in the Z direction. The electric field intensity in each of the provided gas flow paths 3 depends on the angle of the inclined surface and the like. In processing such as cutting during manufacturing, it is difficult from the viewpoint of processing accuracy to obtain a shape that has perfect symmetry with respect to the Z direction. That is, when the plasma generator 1 shown in FIG. 2 is manufactured, the channel width and inclination of each gas channel 3 spaced apart in the Z direction, and the inner surface of the gas channel 3 during cutting It is assumed that the shapes and the like of the provided unevenness are different from each other. As a result, even if the gas delivery device 61 is common to each gas flow path 3, the flow velocity of the gas flowing through each gas flow path 3 tends to be slightly different from each other.

(Modification)
The configuration of the plasma generator 1 described above is merely an example, and various variations can be adopted for the plasma generator 1 of the present embodiment. The structure of each variation will be described below with reference to FIGS. 9A to 9J displayed in the same manner as in FIG.

<1> In the case of the configuration shown in FIG. 7, the first electrode 10 had a shape in which the thickness (the length in the Z direction) decreased as it progressed in the +X direction. On the other hand, as shown in FIG. 9A, the first electrode 10 may have a uniform thickness regardless of the X-coordinate position. That is, the first electrode 10 may have the flat surface 11 even at a position near the first end 71 .

<2> In the case of the configuration shown in FIG. 7, the dielectric substrate 30 had a shape in which the thickness (the length in the Z direction) decreased as it progressed in the +X direction. On the other hand, as shown in FIG. 9B, the dielectric substrate 30 may have a uniform thickness regardless of the X-coordinate position. That is, the dielectric substrate 30 may have the flat surface 31 even at a position near the first end 71 .

<3> In the case of the configuration shown in FIG. 7, the second electrode 20 is provided with the inclined surface 22 so that the thickness (the length in the Z direction) increases as it progresses in the +X direction. In other words, the shape was such that the second electrode 20 was the thickest at the position closest to the first end 71 in the X direction. On the other hand, as shown in FIG. 9C, the inclination of the inclined surface 22 of the second electrode 20 may be set so that the thickness is slightly reduced at the position closest to the first end 71 in the X direction. do not have. More specifically, in the region 81 shown in FIG. 9C, the second electrode 20 is inclined away from the dielectric substrate 30 in the Z direction.

<4> In the case of the configuration shown in FIG. 7, the first electrode 10 had a shape in which the thickness (the length in the Z direction) decreased as it progressed in the +X direction. Moreover, in the case of the configuration shown in FIG. 9A, the thickness of the first electrode 10 was uniform regardless of the position of the X coordinate. On the other hand, as shown in FIG. 9D, the first electrode 10 may have a shape in which the thickness increases in the +X direction. That is, the first electrode 10 may have the inclined surface 12 at a position near the first end 71 so as to approach the second electrode 20 in the Z direction.

<5> In the configuration shown in FIG. 7 , the +X side end of the first electrode 10 was covered with the dielectric substrate 30 . On the other hand, as shown in FIG. 9E , the +X side end of the first electrode 10 may be covered with an insulating member 82 made of a material different from that of the dielectric substrate 30 . By covering the +X side end of the first electrode 10 with the insulating member 82 , generation of unnecessary discharge such as corona discharge can be suppressed, as in the case of covering with the dielectric substrate 30 . Materials for the insulating member 82 include glass, a sintered body containing glass, and a resin material such as silicone or epoxy.

<6> In the configuration shown in FIG. 7 , the +X side end of the first electrode 10 was covered with the dielectric substrate 30 . On the other hand, as shown in FIGS. 9F to 9G, while the +X side end of the first electrode 10 is not covered with the dielectric substrate 30, the dielectric substrate at the position outside the first electrode 10 in the Z direction The +X side end of the body substrate 30 may protrude further to the +X side than the +X side end of the first electrode 10 .

In this case, the +X side end of the first electrode 10 may be located on the -X side of the first end 71 as shown in FIG. 9F, or the first end 71 as shown in FIG. 9G. It may be located on the +X side of . Although not shown, the +X side end of the first electrode 10 may be positioned at the same X coordinate as the first end 71 .

As shown in FIGS. 9F to 9G, even in a structure in which the +X side end of the first electrode 10 is not covered with the dielectric substrate 30, the surrounding dielectric substrate 30 protrudes to the +X side. , an electrical distance is secured between the first electrode 10 and the second electrode 20, and direct discharge is suppressed.

<7> As shown in FIG. 9H, a protective film 85 may be formed on the surface of the second electrode 20 near the outlet 5 . This protective film 85 is provided for the purpose of preventing the material forming the second electrode 20 from scattering. In the example of FIG. 9H, the second electrode 20 has an inclined surface 22, and the protective film 85 is formed on this inclined surface 22. In the example of FIG. As the material of the protective film 85 , for example, aluminum oxide, aluminum nitride, or steatite can be used, and it is preferably the same material as the dielectric substrate 30 .

The method of forming the protective film 85 on the surface of the second electrode 20 is not particularly limited. A preferred method is to The thickness of the protective film 85 can be appropriately set as long as it has the function of suppressing scattering of the material of the second electrode 20, and is, for example, 10 μm to 100 μm.

<8> As shown in FIG. 9I, a starting assisting member 86 may be formed on the surface of the dielectric substrate 30 near the air outlet 5 . Examples of materials for the starting assist member 86 include carbon, transition metal compounds, and the like. A material having a dielectric constant higher than that of the dielectric substrate 30 can be used as the material of the starting assisting member 86 . At this time, dielectric loss heats the constituent material of the starting assisting member 86 and supplies the initial electrons into the gas flow path 3 . Carbon is particularly preferable as the material for the starting assist member 86 . Since carbon has high thermal stability, the starting assisting member 86 is less likely to evaporate even if the temperature rises, and the reliability of the plasma generator 1 is enhanced.

As the material of the starting assisting member 86, a material having a low work function may be used so that the electron emission effect can be recognized with a lower applied voltage.

According to the plasma generator 1 shown in FIG. 9I, since the start assisting member 86 is provided near the outlet 5, the initial electrons can be supplied into the gas flow path 3, and the startability is improved. This eliminates the need for a microwave oscillator or starter circuit device having a large power supply capacity, and the plasma generator 1 can be manufactured in a small size and at a low cost.

<9> As shown in FIG. 9J, the plasma generator 1 may be provided with a light blocking member 87 adjacent to the outlet 5 on the +X side. The light shielding member 87 has a tubular body 88 inside which gas can flow, and this tubular body 88 is connected to the gas flow path 3 . In the example shown in FIG. 9J, the blowing direction of the plasma gas G1 is changed to the -Z direction by the tubular body 88. In the example shown in FIG. Such a configuration prevents the object to be processed from being irradiated with the light originating from the discharge in the gas flow path 3 .

<10> As shown in FIG. 9K, the +X side end of the dielectric substrate 30 may recede from the first end 71 toward the −X side by a very small distance. In this case, the plasma gas G1 flowing through the +Z side gas flow path 3 and the plasma gas G1 flowing through the -Z side gas flow path 3 are blown out from the common blowout port 5 .

<11> The modifications described above can be combined as appropriate.

[Second embodiment]
A second embodiment of the dielectric barrier discharge plasma generator will be described with reference to the drawings. In the following description, elements common to those of the first embodiment are denoted by common reference numerals, thereby appropriately simplifying or omitting the description.

FIG. 10 is a perspective view schematically showing the plasma generator 1 of this embodiment. FIG. 11 is a schematic cross-sectional view of the plasma generator 1 in FIG. 10 taken along line XI-XI. FIG. 12 is a schematic cross-sectional view of the plasma generator 1 in FIG. 10 taken along line XII-XII. FIGS. 10-12 are illustrated in the fashion of FIGS. 1-3, respectively.

The plasma generator 1 of this embodiment includes a housing 45 arranged to sandwich the second electrode 20 in the Y direction. The housing 45 may be made of any material, and may be made of a conductive member such as metal, or may be made of an insulating member such as ceramics or resin.

(Dielectric substrate 30)
As shown in FIGS. 10 to 12, the dielectric substrate 30 is a plate member extending in the Y direction. However, unlike the first embodiment, the plasma generator 1 of this embodiment has a pair of dielectric substrates 30 spaced apart in the Z direction, as shown in FIG.

The same material as in the first embodiment can be used for the dielectric substrate 30 .

(First electrode 10)
As shown in FIG. 11, in the plasma generator 1 of this embodiment, a pair of first electrodes 10 are arranged in a state of being spaced apart in the Z direction. More specifically, each first electrode 10 is arranged on the outer surface of the dielectric substrate 30 , that is, the surface that does not constitute the inner surface of the gas flow path 3 . The material of the first electrode 10 is the same as in the first embodiment.

In addition, in the case of this embodiment, since the first electrode 10 is formed on the outer surface of the dielectric substrate 30, it is possible to adopt a metal foil. As an example, metal foils such as copper foils and aluminum foils having one side subjected to adhesive processing can be mentioned.

As another example, the first electrode 10 may be a sintered body containing a conductive metal. Since the metal-containing sintered body can be formed by printing a metal paste on the surface of the dielectric substrate 30, there is no need to use an adhesive during manufacturing. From the viewpoint of not using an adhesive, the first electrode 10 can also be formed by plating, vapor deposition, sputtering, or thermal spraying.

Also in this embodiment, as in the first embodiment, the first electrode 10 and the dielectric substrate 30 are in close contact with each other as much as possible, and it is preferable that there is no air layer at the interface between the two.

(Second electrode 20, gas flow path 3)
The second electrode 20 has a plate shape extending in the Y direction. As shown in FIGS. 11 and 12, in the plasma generator 1 of this embodiment, the second electrode 20 is arranged so as to be sandwiched between a pair of dielectric substrates 30 spaced apart in the Z direction. . That is, also in this embodiment, the second electrode 20 is spaced apart from the dielectric substrate 30 on the side opposite to the side on which the first electrode 10 is arranged in the Z direction.

As shown in FIG. 12, the second electrode 20 is in contact with the dielectric substrate 30 at both ends in the Y direction. The second electrode 20 has a concave portion 27 in the central portion in the Y direction. In other words, when the edge of the second electrode 20 and the dielectric substrate 30 are brought into contact with each other, the concave portion 27 formed in the second electrode 20 becomes form a void. The gap formed by this concave portion 27 constitutes the "gas flow path 3".

(Gas buffer substrate 40)
The plasma generator 1 of this embodiment includes a gas buffer substrate 40 in contact with the dielectric substrate 30 at a position on the −X side of the second electrode 20 . The gas buffer substrate 40 has a gap 51 into which the gas G0 from the gas delivery device 61 is introduced.

The gas buffer substrate 40 has communication holes 53 at a plurality of different positions in the Y direction. When the gas G<b>0 is delivered from the gas delivery device 61 , it is buffered in the gap 51 and then led to the gas flow path 3 through the communication hole 53 . However, the communication hole 53 may be a single hole extending in the Y direction.

(Blowout port 5)
The plasma generator 1 includes a blowout port 5 at the +X side end of the gas flow path 3 , that is, at the first end 71 . Also in the present embodiment, the plasma generated while flowing along the +X direction in the gas flow path 3 is blown outside from the outlet 5 together with the gas flow (plasma gas G1).

FIG. 13 is a cross-sectional view in which only the first electrode 10, the second electrode 20, and the dielectric substrate 30 are extracted from the plasma generator 1 shown in FIG. 11, and the vicinity of the first end 71 is enlarged and displayed. .

In the plasma generator 1 of this embodiment, the dielectric substrate 30 has a flat surface 31 forming the inner side surface of the gas channel 3 . In addition, the dielectric substrate 30 is located on the +X side (first end 71 side) of the flat surface 33 and the flat surface 33 on the opposite side of the flat surface 31, that is, on the outer side of the gas flow path 3. and an inclined surface 34 that

The first electrode 10 is arranged at least on the upper surface of the inclined surface 34 . In addition, in the example of FIG. 13 , part of the first electrode 10 is also arranged on the upper surface of the flat surface 33 .

Both the +Z side surface and the −Z side surface of the second electrode 20 constitute the inner side surfaces of the gas flow path 3, and each of them is a flat surface 21 and a +X side of the flat surface 21 ( and an inclined surface 22 located on the first end 71 side).

In this manner, at least one surface of the dielectric substrate 30, the first electrode 10, and the second electrode 20 has an inclined surface at a position near the first end 71 in the X direction, that is, at a position near the air outlet 5. Thus, as the gas flows through the gas passage 3 and approaches the outlet 5 , the electric field strength applied to the gas is increased, and plasma is generated in the vicinity of the outlet 5 .

14 is a partially enlarged view of FIG. 13. FIG. 14 also shows the workpiece W to be sprayed with the plasma gas G1 for convenience of explanation, as in FIG. The object W to be processed is blown with the plasma gas G1 while moving in the Z direction.

Also in the plasma generator 1 of this embodiment, gas flow paths 3 are formed at a plurality of locations spaced apart in the Z direction, as in the first embodiment. The gas flowing in the +X direction through these gas flow paths 3 is plasmatized in the vicinity of the first end 71 , and is sprayed onto the workpiece W from the outlet 5 as the plasma gas G<b>1 .

In the present embodiment, the separation distance in the Z direction between the gas flow paths 3 at positions close to the first end 71 in the X direction is the thickness (Z direction length), ie depending on the thickness of the end 29 of the second electrode 20 . In order to plasmatize the flowing gas, it is necessary to apply a high electric field to the gas, and from this point of view, the thickness of the second electrode 20 has an upper limit. The thickness of the end portion 29 of the second electrode 20 is set to 1.0 mm to 10.0 mm.

That is, according to the plasma generator 1 of the present embodiment, the plasma gas G1 is sprayed onto the workpiece W from a plurality of positions (a plurality of outlets 5) separated by a distance of less than 10.0 mm in the Z direction. . Therefore, for the same reason as in the plasma generator 1 of the first embodiment, a gas space PA filled with the plasma gas G1 is formed in a region wider than the opening width of each outlet 5 . Therefore, the surface treatment capability for the object W to be treated is improved.

(Modification)
The configuration of the plasma generator 1 described above with reference to FIGS. 10 to 14 is merely an example, and various variations can be adopted for the plasma generator 1 of the present embodiment. The structure of each variation will be described below with reference to FIGS.

<1> In the case of the configuration shown in FIG. 10, the dielectric substrate 30 had a shape in which the thickness (the length in the Z direction) decreased as it progressed in the +X direction. More specifically, the inclined surface 34 of the dielectric substrate 30 was inclined so as to approach the gas flow path 3 as it progressed in the +X direction. On the other hand, as shown in FIG. 15A, the dielectric substrate 30 may have a shape in which the thickness increases in the +X direction. In other words, the slanted surface 34 of the dielectric substrate 30 may be slanted away from the gas flow path 3 as it progresses in the +X direction.

<2> In the case of the configuration shown in FIG. 10, the second electrode 20 is provided with the inclined surface 22 so that the thickness (the length in the Z direction) increases in the +X direction. In other words, the shape was such that the second electrode 20 was the thickest at the position closest to the first end 71 in the X direction. On the other hand, as in FIG. 9C described above, even if the inclination of the inclined surface 22 is set so that the thickness of the second electrode 20 is slightly reduced at the position closest to the first end 71 in the X direction, No problem (see FIG. 15B). More specifically, in the region 81 shown in FIG. 15B, the second electrode 20 is inclined away from the dielectric substrate 30 in the Z direction.

<3> As shown in FIG. 15C, the dielectric substrate 30 may be provided with an insulating member 91 that abuts on the +X side end of the first electrode 10 . According to this configuration, the insulating member 91 is provided between the first electrode 10 and the outlet 5 in the X direction, thereby ensuring the creeping distance between the first electrode 10 and the second electrode 20 on the outlet 5 side. be done. This suppresses unnecessary discharge such as a short circuit between the first electrode 10 and the second electrode 20 and occurrence of creeping discharge.

Examples of the material of the insulating member 91 include the materials exemplified as the material of the dielectric substrate 30 .

In addition, as shown in FIG. 15D , the dielectric substrate 30 may be provided with an insulating protrusion 92 at a position spaced apart from the +X side end of the first electrode 10 . Although the example shown in FIG. 15D illustrates the case where the protrusion 92 is formed integrally with the dielectric substrate 30, the protrusion 92 may be formed of a member different from the dielectric substrate 30.

<4> As described above with reference to FIG. 9H, also in the present embodiment, a protective film 85 may be formed on the surface of the second electrode 20 near the outlet 5 (FIG. 15E reference).

As described above with reference to FIG. 9I, also in this embodiment, a starting assisting member 86 may be formed on the surface of the dielectric substrate 30 near the air outlet 5 (see FIG. 15F). .

As described above with reference to FIG. 9J, also in this embodiment, the light blocking member 87 may be provided at a position adjacent to the +X side of the outlet 5 (see FIG. 15G).

<6> As shown in FIG. 15H, the +X side end of the second electrode 20 may be set back from the first end 71 to the -X side by a very small distance. In this case, the plasma gas G1 flowing through the +Z side gas flow path 3 and the plasma gas G1 flowing through the -Z side gas flow path 3 are blown out from the common blowout port 5 .

<7> FIG. 11 illustrates a case where a common power supply device 63 is connected to a pair of first electrodes 10 . However, a separate power supply device 63 may be connected to each first electrode 10 .

<8> The modifications described above can be combined as appropriate.

Reference Signs List 1: dielectric barrier discharge plasma generator 3: gas flow path 5: outlet 10: first electrode 20: second electrode 27: recess 30: dielectric substrate 40: gas buffer substrate 45: housing 51: space 53 : Communication hole 61 : Gas delivery device 63 : Power supply device 82 : Insulating member 85 : Protective film 86 : Start assisting member 87 : Light shielding member 88 : Tubular body 91 : Insulating member 92 : Protrusion

Claims (10)

a plate-shaped dielectric substrate extending in a first direction;
a first electrode arranged in contact with the surface of the dielectric substrate;
with respect to a second direction perpendicular to the first direction, the electrode is arranged to extend in the first direction while being separated from the dielectric substrate on the side opposite to the side on which the first electrode is arranged. a second electrode;
a gas flow path formed by a gap between the dielectric substrate and the second electrode in the second direction, through which gas flows in a third direction orthogonal to the first direction and the second direction;
an outlet provided at one end of the gas channel in the third direction and extending in the first direction;
When viewed in the first direction, at least one of the dielectric substrate, the first electrode, and the second electrode extends from a predetermined location to the outlet in the third direction. having an inclined surface,
One of the dielectric substrate and the second electrode is arranged so as to sandwich the other of the dielectric substrate and the second electrode in the second direction with the gap interposed therebetween. A dielectric barrier discharge plasma generator. The gas flow path is formed at two locations spaced apart in the second direction,
2. The dielectric barrier discharge plasma generator according to claim 1, wherein said outlets are arranged corresponding to respective gas flow paths. The dielectric substrate has a slit-shaped hole extending parallel to the main surface,
the first electrode has a plate shape and is embedded in the hole to be in contact with the dielectric substrate;
3. The dielectric barrier discharge plasma generation according to claim 1, wherein the second electrodes are arranged to sandwich the dielectric substrate from both sides in the first direction with a space therebetween. Device. The first electrode is an electrode on the high voltage side,
4. The dielectric barrier discharge plasma generator according to claim 3, wherein said second electrode is an electrode on the low voltage side. a gas buffer substrate in contact with the pair of second electrodes from the outside at peripheral edge portions;
a gas delivery device for introducing the gas into a gap sandwiched between the gas buffer substrate and the second electrode;
4. The dielectric barrier discharge plasma generator according to claim 3, further comprising communication holes penetrating said second electrode in said second direction at a plurality of locations in said first direction. 4. The dielectric barrier discharge plasma generator according to claim 3, wherein the main material of said dielectric substrate is aluminum oxide or aluminum nitride. a pair of the dielectric substrates are spaced apart in the second direction,
a pair of the first electrodes disposed on respective outer surfaces of the pair of dielectric substrates;
3. The dielectric barrier according to claim 1, wherein the second electrode is arranged at a position spaced apart in the second direction from inner surfaces of the pair of dielectric substrates. Discharge plasma generator. The first electrode is an electrode on the high voltage side,
8. The dielectric barrier discharge plasma generator according to claim 7, wherein said second electrode is an electrode on the low voltage side. 8. The dielectric substrate according to claim 7, further comprising an insulating protrusion disposed between the first electrode and the outlet in the third direction on the surface of the dielectric substrate. dielectric barrier discharge plasma generator. 8. The dielectric barrier discharge plasma generator according to claim 7, wherein the main material of said dielectric substrate is aluminum oxide or aluminum nitride.

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