JP2014154248A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing device capable of efficiently processing a surface of a processed body.SOLUTION: A plasma processing device includes a ground electrode 2; and a high-pressure electrode 3 which is disposed so as to oppose to the ground electrode 2 through a cavity 7, and has a conductive layer. By supplying discharging gas into the cavity 7 and applying high voltage on the high-pressure electrode 3, discharge is generated near atmospheric pressure in the cavity 7. The discharging gas including atomic oxygen generated by the discharge is jetted out from slits 11a and 11b formed on the ground electrode 2, and the atomic oxygen is contacted with a honeycombs structure 13, thereby processing a surface of the honeycombs structure 13. One pair of the slits 11a and 11b is oriented so as to make the discharging gas intersect each other between the ground electrode 2 and the honeycomb structure 13.

Description

  The present invention relates to a plasma processing apparatus for irradiating a processing body with active particles generated by discharge near atmospheric pressure, for example, for pretreatment of bonding and surface cleaning.

In recent years, the use of honeycomb sandwich panels formed by bonding metal honeycombs such as aluminum in a sandwich shape with a composite material sheet has been expanding. Honeycomb sandwich panels are lightweight and have high strength, and are used in the aerospace field, electric railway field, building material field, and the like. In the honeycomb sandwich panel structure, the adhesive strength between the metal honeycomb and the composite material sheet is one of the main characteristics, and application of plasma treatment for improving the adhesive strength is expected.
Conventionally, as a plasma processing apparatus, an electrode to which a high frequency voltage is applied is covered with an inner plate and an outer plate made of ceramic, and microplasma is generated at the tip of the electrode, and processing of an object to be processed from a gas flow path between the ceramic plates. An etching apparatus for ejecting gas toward a line or a point to be subjected to is shown. According to this structure, for example, helium is used as an inert gas and sulfur hexafluoride is used as a reaction gas, so that a minute portion on the surface of an object to be processed is etched (patent) Reference 1).

There is also known a plasma processing apparatus that generates plasma between an electric field application electrode and a plate-like ground electrode and irradiates a processing body with a processing gas from a blowout port formed in the ground electrode (Patent Document 2). reference). Here, the blow-out opening penetrates in a fixed direction in the thickness direction of the ground electrode.
According to this plasma processing apparatus, the processing gas can be blown obliquely and directed to prevent turbulence, and the exhaust gas can be smoothly discharged from between the ground electrode and the object to be processed. Retention can be prevented.

Japanese Patent Laying-Open No. 2005-32797 (page 2, FIG. 1) Japanese Patent No. 4077704 (pages 1, 16-17, FIG. 18)

However, in the plasma processing apparatus disclosed in Patent Document 1, the high voltage electrode, the inner plate, and the outer plate are arranged on a surface perpendicular to the workpiece, and the tip of the high voltage electrode on the workpiece side is pointed. Have a structure. For this reason, when trying to process a narrow end surface of a member having a hollow structure such as a metal honeycomb, for example, arc discharge may occur between the electrode and the end surface of the honeycomb structure, and the honeycomb structure may be damaged. .
In addition, by processing gas on the surface of the workpiece or blowing gas toward the line, it is possible to selectively process a narrow area, but on the contrary, try to process a large workpiece at high speed. In this case, it is inevitable to increase the number of component parts of the apparatus and increase the size of the apparatus itself, such as preparing a plurality of electrodes.

  In addition, the plasma processing apparatus disclosed in Patent Document 2 has an effect that the exhaust is smoothly performed on a flat plate-shaped processing body because the blowout port formed in the ground electrode is inclined in a certain direction. However, when processing is performed on a surface such as a honeycomb structure in which the angle between the blowing direction of the plasma and the processing surface is not constant, there is a problem that the plasma processing becomes non-uniform depending on the direction.

  An object of the present invention is to provide a plasma processing apparatus capable of efficiently treating the surface of a member having a hollow structure such as a honeycomb structure. To do.

A plasma processing apparatus according to the present invention includes a ground electrode, a high-voltage electrode having a conductive layer disposed so as to face the ground electrode with a gap, and at least the surface on the gap side is covered with a dielectric. A discharge containing active particles generated in the discharge by supplying a gas to be discharged to the gap and applying a high voltage to the high-voltage electrode to generate a discharge in the vicinity of atmospheric pressure. A plasma processing apparatus for processing a surface of the processing body by ejecting gas from a gas ejection hole formed in the ground electrode and bringing the active particles into contact with the processing body facing the ground electrode,
At least a pair of the gas ejection holes are directed so that the discharge gas intersects between the ground electrode and the processing body.

  According to the plasma processing apparatus of the present invention, since at least the pair of gas ejection holes are directed so that the discharge gas intersects between the ground electrode and the processing body, the ground electrode and the processing body The gas flows of the discharge gas intersect with each other to generate a turbulent flow, the active particles stay in the vicinity of the surface of the processing body, and the surface is efficiently processed.

It is sectional drawing which shows the plasma processing apparatus which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the principal part of FIG. It is a figure which shows the calculation result of the oxygen concentration dependence of the annihilation rate of atomic oxygen. 4 (a) and 4 (b) are schematic views showing the problems of the surface treatment of the honeycomb structure end face according to the prior art. 5 (a) is an exploded perspective view showing a ground electrode of a plasma processing apparatus according to Embodiment 2 of the present invention, FIG. 5 (b) is a front view of FIG. 5 (a), and FIG. 5 (c) is FIG. It is a front sectional view of (b). 6 (a) and 6 (b) are schematic views showing gas flows in the slits of the plasma processing apparatus according to Embodiment 2 of the present invention. It is sectional drawing which shows the plasma processing apparatus which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the plasma processing apparatus which concerns on Embodiment 4 of this invention. It is a schematic diagram which shows the discharge gas ejection part and gas flow of the plasma processing apparatus which concerns on Embodiment 5 of this invention. It is sectional drawing which shows the plasma processing apparatus which concerns on Embodiment 6 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or equivalent members and parts will be described with the same reference numerals.

Embodiment 1 FIG.
1 is a sectional view showing a plasma processing apparatus according to Embodiment 1 of the present invention.
The plasma processing apparatus includes an atmospheric pressure plasma unit 1 and a drive mechanism 12 connected to the atmospheric pressure plasma unit 1 and reciprocating the atmospheric pressure plasma unit 1 in the horizontal direction.
The atmospheric pressure plasma unit 1 includes a ground electrode 2, a high-voltage electrode 3 opposed to the ground electrode 2 through a gap 7, a casing 4 covering the high-voltage electrode 3, and a gas supply port 10 of the casing 4. The pipe 23 to which the tip is connected, the first flow rate controller 9a attached to the first pipe part 23a of the pipe 23, and the second flow rate attached to the second pipe part 23b of the pipe 23 A regulator 9b and a high voltage power supply 8 electrically connected to the high voltage electrode 3 are provided.
The high voltage electrode 3 includes a dielectric 5 and a conductive layer 6 embedded in the dielectric 5. The conductive layer 6 is connected to a high voltage power source 8 and the ground electrode 2 is electrically grounded.
On the opposite side of the gap 7 of the ground electrode 2, a honeycomb structure 13 which is a treatment body is placed.
The honeycomb structure 13 is made of, for example, aluminum, and is manufactured as a honeycomb sandwich panel by adhering the honeycomb structure 13 in a sandwich shape with a composite material sheet.

Nitrogen gas, which is an inert gas, passes through the first pipe portion 23a, and dry air passes through the second pipe portion 23b, and the nitrogen gas and dry air merge to form a mixed gas, and the housing The gas is supplied from the gas supply port 10 formed in 4 into the housing 4.
The ground electrode 2 is formed with a pair of slits 11a and 11b which are gas ejection holes penetrating the ground electrode 2 in the thickness direction. The slits 11a and 11b have curved surfaces 90a and 90b that protrude downward so that the distance between the slits 11a and 11b becomes closer toward the downstream of the gas flow, and have passed through the slits 11a and 11b. The gas flow of the discharge gas (the gas containing atomic oxygen generated by the discharge in the gap 7) intersects between the ground electrode 2 and the honeycomb structure 13.

Next, the operation of the plasma processing apparatus of the first embodiment will be described.
First, nitrogen gas is supplied to the inside of the housing 4 through the first piping part 23a and dry air is supplied through the second piping part 23b.
At this time, the gas flow rates of the nitrogen gas and the dry air are set so that the oxygen concentration in the mixed gas, which is the gas supplied to the discharge, becomes about 100 ppm by the first flow rate regulator 9a and the second flow rate regulator 9b. Adjust.
The mixed gas supplied to the inside of the housing 4 passes through the gap 7 from the outer periphery to the center of the high-voltage electrode 3, and is ejected to the outside of the housing 4 through the slits 11 a and 11 b.
Here, the transport time t () obtained by dividing the distance D (m) between the ground electrode 2 and the honeycomb end face 28 which is the surface of the honeycomb structure 13 by the velocity v (m / s) of the jetted gas 31. The supply amount of the mixed gas and the opening areas of the slits 11a and 11b are determined so that s) is 1 millisecond or less.
Then, by operating the high voltage power supply 8 and applying an alternating high voltage to the conductive layer 6, a plasma 25 is formed in the gap 7 near atmospheric pressure.
Various reactions occur in the plasma field. In particular, the reaction of the formula (1) occurs, and a discharge gas containing atomic oxygen as active particles is generated.

O ₂ + e → O + O + e (1)

FIG. 2 is a schematic diagram showing the ground electrode 2 and its vicinity.
As shown in FIG. 2, the discharge gas containing atomic oxygen generated in the reaction (1) passes through the slits 11 a and 11 b, and then between the ground electrode 2 and the honeycomb end face 28 that is the surface of the honeycomb structure 13. Intersect at gas intersection 26 between.
As a result, turbulent flow is generated in the vicinity of the gas intersection 26, and the discharge gas containing atomic oxygen does not flow in the depth direction of the honeycomb structure 13, but radicals along the honeycomb end face 28 of the honeycomb structure 13. It stays in the staying place 27.
Then, by moving the atmospheric pressure plasma unit 1 in the horizontal direction by the drive mechanism 12, the entire area of the honeycomb end face 28 is efficiently processed.

Next, the reason why the honeycomb end surface 28 of the honeycomb structure 13 is efficiently processed when the plasma processing apparatus of this embodiment is used will be described.
Atomic oxygen generated in the plasma 25 is extinguished at a high speed by the reaction of the formula (2) with oxygen in the normal atmosphere in the transport field from the plasma field to the honeycomb structure 13. .

O + O ₂ + M → O ₃ + M (2)
Here, O ₃ is ozone, and M is any atom or molecule present in the atmosphere.
In the reaction of formula (2), atomic oxygen disappears and ozone is generated. However, ozone is less active than atomic oxygen, and the surface treatment effect is remarkably small. Further, the reaction frequency of the equation (2) is proportional to the oxygen concentration in the transport field. When the atmospheric pressure plasma treatment is performed on the planar processed body, the outside air is quickly removed from the transport field, resulting in a low oxygen concentration atmosphere.
For this reason, the reaction of the formula (2) is suppressed, atomic oxygen can easily reach the treatment body, and an effective treatment can be achieved even with the conventional apparatus.
On the other hand, when the treatment body is a member having a hollow structure such as a honeycomb structure or a box-shaped member, since the low oxygen concentration atmosphere is difficult to be formed in the transport field, the reaction (2) occurs remarkably, and the atomic oxygen Many disappear before reaching the treatment object. For this reason, the conventional apparatus cannot obtain a sufficient processing effect.

Here, the result of calculating the disappearance rate of the atomic oxygen number density using the oxygen concentration of the transport field as a parameter is shown in FIG.
It should be noted that the reaction rate coefficient of the formula (2) is calculated according to non-patent literature (IA Kossyi, A Yu Kostinsky, AA Maveyev and VP Silakov, “Kinetic scheme of the non-equilibrium discharrge in nitrogen oxygen mixture”, Plasma Sources Sci. Technol. , 1 (1992) 207-220) to 6.7 × 10 ⁻³⁴ (cm ⁶ / s), and the atomic oxygen number density at time zero was set to 1 × 10 ¹⁵ (cm ⁻³ ).

From FIG. 3, it can be seen that the rate of disappearance of atomic oxygen increases remarkably as the oxygen concentration in the transport field increases.
The inventor of the present application supplies an oxygen concentration of 0.01 to 0.1% to the atmospheric pressure plasma unit 1 and determines the oxygen concentration of the transport field when the metal honeycomb structure 13 is used as a processing target. Measured with an oxygen concentration meter.
As a result, a result of approximately 0.1 to 1% was obtained, although it varied somewhat depending on the flow rate of the discharge gas and the shape of the metal honeycomb structure 13.
Therefore, as shown in FIG. 3, if the atomic oxygen that has passed through the plasma field reaches the honeycomb structure 13 within 1 millisecond, the number density drop will be within an order of magnitude, and processing will be performed with high efficiency. It was expected.
On the other hand, in order to avoid contact between the ground electrode 2 and the honeycomb structure 13, generally, a clearance of about several millimeters is required between them.
Therefore, the transport time t (s) obtained by dividing the distance D (m) between the ground electrode 2 and the honeycomb end face 28 by the velocity v (m / s) of the jetted gas 31 is 1 millisecond or less. It is necessary to set as follows.

On the other hand, as can be seen from FIG. 3, the shorter the transport time, that is, the higher the discharge gas ejection speed, the higher the atomic oxygen can be supplied to the object to be processed.
In order to increase the ejection speed, there are a method of increasing the supply amount of the mixed gas supplied to the discharge and a method of narrowing the opening areas of the slits 11a and 11b.
The former is not preferable because it causes an increase in running cost associated with an increase in the amount of mixed gas used, an increase in power for converting a large flow rate gas into plasma, and an increase in the size of the apparatus.
On the other hand, even in the latter case, the honeycomb structure 13 cannot be processed efficiently for the following reason.

4A is a schematic diagram illustrating a case where the wide vertical slit 30 is provided, and FIG. 4B schematically illustrates a case where the wide vertical slit 32 is provided.
In the case of FIG. 4A, since the opening area of the gas ejection portion is large, the velocity of the gas 31 ejected from the plasma 25 is slow. For this reason, the transport time is long, and most of the atomic oxygen disappears before reaching the honeycomb structure 13 and an effective surface treatment is not performed.
On the other hand, in the case of FIG. 4B, since the opening area of the gas ejection portion is small, the velocity of the gas 33 ejected from the plasma 25 is high. For this reason, the transport time is short, and most of the atomic oxygen reaches the honeycomb structure 13.
However, when the plasma processing apparatus is driven in the horizontal direction with respect to the honeycomb structure 13, the width of the jetted gas 33 is narrow, so that it passes through the partition walls of the honeycomb structure 13 in an extremely short time. Atomic oxygen reaches 13 depth directions.
In general, in the manufacture of a honeycomb sandwich panel, the bonded portion of the honeycomb structure 13 is very close to the end face, and only this portion needs to be plasma-treated. When the atomic oxygen reaches the part that is not bonded, the efficiency of the plasma processing is lowered. Therefore, it is desirable that the atomic oxygen be concentratedly supplied in the vicinity of the end face of the honeycomb structure 13.

From the above, in order to realize an efficient treatment of the honeycomb end face 28 having a hollow structure such as the honeycomb structure 13, the discharge speed of the discharge gas from the slits 11a and 11b is increased as much as possible, and the atomic oxygen It is necessary to concentrate the distribution of atomic oxygen in the vicinity of the honeycomb end face 28 that requires surface modification.
In a conventional plasma processing apparatus, if the slit opening area is narrowed and atomic oxygen is transported in a short time, the processing efficiency of the honeycomb structure 13 becomes very bad. When the ejection width is increased, there is a dilemma that atomic oxygen disappears before reaching the honeycomb end face 28 of the honeycomb structure 13.

According to the plasma processing apparatus of this embodiment, the distance D (m) between the ground electrode 2 and the honeycomb end face 28 is divided by the discharge gas ejection speed v (m / s) from the slits 11a and 11b. By setting the discharge gas transport time t (s) obtained in this manner to be 1 millisecond or less, the decrease in atomic oxygen number density is within about one digit, and surface treatment is performed with high efficiency.
Furthermore, curved surfaces are formed in the slits 11a and 11b in FIG. 1, and a turbulent flow is generated by crossing the gas flow between the ground electrode 2 and the honeycomb structure 13, and the vicinity of the honeycomb end face 28 of the honeycomb structure 13 It is possible to concentrate the distribution of atomic oxygen.
Thereby, the efficient process of the honeycomb end surface 28 of the honeycomb structure 13 which was not realized in the conventional apparatus is realized.

In the present invention, the vicinity of atmospheric pressure means that the absolute pressure is between 1/10 atm and 5 atm. When the pressure is 1/10 atm or less, the reaction rate of the formula (2) becomes low and the transport of atomic oxygen becomes easy. For this reason, there is no merit of applying the method and apparatus shown in the present invention.
On the other hand, if the pressure exceeds 5 atm, a very high voltage is required for plasma formation, and the cost increases remarkably as the power source becomes larger and the insulation design becomes difficult, making it unsuitable for practical use.

The lengths and widths of the slits 11a and 11b in this embodiment take into consideration the discharge gas flow rate, the distance between the ground electrode 2 and the processing body, the shape of the processing body, etc. It can be set appropriately. Generally, it is desirable that the width of the slits 11a and 11b is 0.05 mm to 10 mm.
If the width of the slits 11a and 11b is set to 0.05 mm or less, not only the processing becomes extremely difficult and the manufacturing cost increases remarkably, but also the slit width varies slightly in the length direction, and the ejected gas is not uniform. And uniform plasma treatment cannot be performed.
Further, if the width of the slits 11a and 11b is 10 mm or more, the opening area of the ground electrode 2 is increased, and a very large amount of discharge gas is required to reduce the discharge gas transport time t to 1 millisecond or less. Increases significantly.

Embodiment 2. FIG.
5A is an exploded perspective view of the ground electrode 22 of the plasma processing apparatus according to the second embodiment of the present invention, FIG. 5B is a plan view of the ground electrode 22, and FIG. 3 is a front sectional view of an electrode 22. FIG.
The ground electrode 22 includes an upper ground electrode portion 14 that is a first ground electrode portion and a lower ground electrode portion 15 that is a second ground electrode portion. The lower ground electrode portion 15 is a rectangular parallelepiped, and a through hole 18 is formed near the center. The side surface on the long side of the through hole 18 has a curved surface 19 in which a part of the downstream side protrudes downward with respect to the thickness direction.
The upper ground electrode portion 14 has a rectangular parallelepiped shape, and a plurality of protrusions 16 are formed on the outer periphery thereof. The side surface on the long side is a curved surface in which a part of the downstream side protrudes downward with respect to the thickness direction. 17. The shape of the through hole 18 of the lower ground electrode portion 15 and the outer dimensions including the protrusion 16 of the upper ground electrode portion 14 are substantially the same, and the ground electrode 22 is formed by fitting the two together.
At the time of fitting, at least the upper surfaces of the upper ground electrode portion 14 and the lower ground electrode portion 15 are substantially the same surface, and a slit opening defined by the protrusion 16 and the side surface of the upper ground electrode portion 14 and the wall surface of the through hole 18. Slits 11a and 11b having portions 20a and 20b are formed.

FIG. 6 is a schematic diagram of the slit 11a formed in the ground electrode 22 of the plasma processing apparatus according to Embodiment 2 of the present invention and the gas flow of the discharge gas.
6 (a) and 6 (b), the lower ground electrode portion 15 has the same shape, but the shape of the upper curved surface 40 of the upper ground electrode portion 14 is different.
6 (a) has a larger radius of curvature than that of FIG. 6 (b), and the gas flow that has passed through the slit 11a is relatively upstream of the upper ground electrode portion 14. A separation point 42 is formed in the gas, and the gas flow of the discharge gas is relatively downward.
On the other hand, in the upper ground electrode portion 14 of FIG. 6B, the separation point 42 moves to the downstream side as compared with that of FIG. 6A, so that the gas flow is more lateral. As a result, in FIG. 6A, the gas flow intersects at a position away from the ground electrode 22 in the vertical direction, and in FIG. 6B, the gas flow of the discharge gas intersects near the ground electrode 22.

Thus, according to the plasma processing apparatus of this embodiment, the crossing position of the gas flow of the discharge gas can be changed by changing the shape of the upper curved surface 40 of the upper ground electrode portion 14.
Thereby, even when the distance between the plasma processing apparatus and the object to be processed and the required modification depth are changed, it is possible to easily perform plasma processing under optimum conditions.
In addition, by making the slit shape as shown in FIG. 6B, the discharge gas ejected from the pair of slits 11a and 11b follows a flow path close to a frontal collision, so that atomic oxygen is more concentrated near the surface layer of the treatment body. Can concentrate.

In this embodiment, only the upper ground electrode portion 14 is changed, but the same effect can be obtained by changing only the lower ground electrode portion 15 or both.
Further, the peeling point 42 is influenced not only by the curved shape of the ground electrode 22 but also by the Reynolds number, the surface roughness of the slits 11a and 11b, and the like. In an actual apparatus, it is necessary to determine the curved surface shape based on these effects.
In this embodiment, the upper ground electrode portion 14 and the lower ground electrode portion 15 both have the upper curved surface 40 and the lower curved surface 41 formed on a part of the downstream side in the thickness direction. It may be over the entire thickness direction. Further, instead of forming the curved surfaces 40 and 41, a linear inclined surface may be formed.
Further, in the present embodiment, the protrusion 16 is formed on the upper ground electrode portion 14, but the protrusion may be formed on the lower ground electrode portion 15. In addition, the slits 11a and 11b can be formed by bonding the upper ground electrode portion 14 and the lower ground electrode 15 by a method such as brazing without forming the protrusions 16.

Embodiment 3 FIG.
FIG. 7 is a sectional view showing a plasma processing apparatus according to Embodiment 3 of the present invention.
In this embodiment, the conductive layer includes a first conductive layer portion 50a and a second conductive layer portion 50b that are spaced apart in the plane direction. The separated first conductive layer portion 50a and second conductive layer portion 50b are connected to a common high-voltage power supply 8 and face the slit openings 20a and 20b which are the entrance portions of the slits 11a and 11b. Yes.
The mixed gas supplied into the housing 4 passes through the gap 7 from the outer peripheral side of the high-voltage electrode 3. At this time, by applying an alternating high voltage to the high-voltage electrode 3, the conductive layer portions 50 a and 50 b and the ground electrode 2, plasmas 51a and 51b are formed, and then a discharge gas containing atomic oxygen is ejected to the outside through the slits 11a and 11b.
Other configurations are the same as those of the plasma processing apparatus of the first embodiment.

In the plasma processing apparatus of the first embodiment shown in FIG. 1, plasma is also formed in the region between the slit 11a and the slit 11b, but the supply gas flows from the outer peripheral side of the gap 7 toward the slits 11a and 11b. Therefore, gas stagnates in the region between the slit 11a and the slit 11b. Even if plasma is generated in this region and atomic oxygen is generated, the oxygen is hardly extracted from the ground electrode 2 and the power consumption is substantially reduced.
In addition, if plasma is generated in a region where gas is stagnant, the temperature of that portion may locally rise, leading to damage to the high-voltage electrode 3 and the ground electrode 2.

  On the other hand, according to this embodiment, generation of plasma between the conductive layer portion 50a and the conductive layer portion 50b is eliminated, wasteful power consumption is suppressed, and damage to the high-voltage electrode 3 and the ground electrode 2 is prevented. Can be reduced.

In this embodiment, there is one slit pair, but a plurality of pairs may be used. In that case, the conductive layer portion may not be formed at a portion facing the middle of each slit pair.
In this embodiment, the gas flow of the discharge gas is directed from the outer periphery of the gap 7 toward the center side where the slits 11a and 11a are formed. In this case as well, plasma may be generated in a portion located upstream of the gas flow of the normal gas with respect to the slits 11a and 11a.
In addition, the conductive layers 50a and 50b are not necessarily embedded in the dielectric 5, and for example, a conductive film that is a conductive layer may be formed on the side surface opposite to the gap 7 of the dielectric plate by vapor deposition or the like.

Embodiment 4 FIG.
FIG. 8 is a cross-sectional view showing a plasma processing apparatus according to Embodiment 4 of the present invention.
In this embodiment, the atmospheric pressure plasma unit 1 moves horizontally to the left with respect to the fixed honeycomb structure 13, and the ground electrode 65 has two pairs of slits 60a and 60b and slits 61a and 61b. Is formed.
The high-voltage electrode 3 includes conductive layer portions 63a and 63b that are spaced apart from each other inside the dielectric 5, and one conductive layer portion 63a is located in the right direction from the facing surface of the slit 61b, and the other conductive layer portion 63b is formed in the slit 60b. It extends to the left from the facing surface.
Other configurations are the same as those of the plasma processing apparatus of the first embodiment.

In this embodiment, plasmas 62a and 62b are formed by applying an alternating high voltage from the high-voltage power supply 8 to the conductive layer portions 63a and 63b. The discharge gas flows from the outer periphery of the high-voltage electrode 3 toward the center in the gap 7 and is ejected to the outside through the slits 60b and 61b.
At this time, a gas not containing much atomic oxygen is ejected from the slit 60a, and a gas containing atomic oxygen is ejected from the slit 60b.
Similarly, a discharge gas containing atomic oxygen is ejected from the slit 61b, and a gas not containing much atomic oxygen is ejected from the slit 61a.
Since the atmospheric pressure plasma unit 1 is driven leftward with respect to the honeycomb structure 13, in the honeycomb structure 13, after the low oxygen concentration gas is supplied from the slits 60 a and 61 a, active particles are passed through the slits 60 b and 61 b. A discharge gas containing certain atomic oxygen is supplied.
As a result, when the atomic oxygen is ejected, outside air is excluded, a low oxygen atmosphere is formed, and the reaction of the above formula (2) is suppressed.

  According to this embodiment, the transport field can be in a low oxygen atmosphere, whereby atomic oxygen can be efficiently transported to the honeycomb structure 13 and the processing efficiency is improved. Further, since the plasma 25 forming region is limited, the power consumption can be reduced compared to the case where the plasma 25 is formed in the entire gap 7.

Embodiment 5 FIG.
FIG. 9 is a schematic diagram showing a discharge gas ejection portion of a plasma processing apparatus according to Embodiment 5 of the present invention.
In this embodiment, a gas supply source 70 is attached to the plasma processing apparatus of the first embodiment shown in FIG.
The gas flow of the discharge gas containing atomic oxygen ejected through the pair of slits 11 a and 11 b intersects at the gas intersection 71.
In this embodiment, a gas supply source 70 is provided below the honeycomb structure 13, and a diffusion gas is supplied toward the gas intersection 71. At this time, the positional relationship between the atmospheric pressure plasma unit 1 and the gas supply source 70 is fixed, and the honeycomb structure 13 moves in the horizontal direction therebetween.

  According to this embodiment, compared to the case where there is no gas supply source 70, the radical staying field 72 further spreads in the lateral direction, and as a result, more atomic oxygen is absorbed in the vicinity of the honeycomb end face 28 of the honeycomb structure 13. It can be concentrated. Thereby, the surface treatment speed of the honeycomb structure 13 is improved.

In this embodiment, an inert gas such as nitrogen, argon or helium may be used as the diffusion gas supplied from the gas supply source 70. In this case, there is an effect of making the transport field a low oxygen atmosphere. When air is supplied, diffusion of atomic oxygen in the depth direction of the honeycomb structure 13 is suppressed, and deterioration of the material can be suppressed. Further, other gases may be used, or a mixed gas may be used.
In this embodiment, the positional relationship between the atmospheric pressure plasma unit 1 and the gas supply source 70 is fixed and the honeycomb structure 13 is moved in the horizontal direction. However, the honeycomb structure 13 is fixed and the atmospheric pressure is The plasma unit 1 and the gas supply source 70 may be driven in the horizontal direction at the same speed.

Embodiment 6 FIG.
FIG. 10 is a sectional view showing a plasma processing apparatus in accordance with Embodiment 6 of the present invention.
In this embodiment, a position sensor 80 that detects the distance between the ground electrode 2 and the honeycomb structure 13 is provided in the housing 4. The drive mechanism 12 includes an actuator 81 that is an adjustment mechanism that moves the atmospheric pressure plasma unit 1 in the vertical direction.
Other configurations are the same as those of the plasma processing apparatus of the first embodiment.

  In this embodiment, when the atmospheric pressure plasma unit 1 is driven in the horizontal direction to process the honeycomb end surface 28 of the honeycomb structure 13, the position sensor 80 causes the honeycomb end surface 28 of the honeycomb structure 13 and the atmospheric pressure plasma unit 1 to be processed. And the actuator 81 is driven so that the distance between the ground electrode 2 and the honeycomb end face 28 of the honeycomb structure 13 is substantially constant based on the data.

In the plasma processing apparatus according to the present invention, since the discharge gas containing atomic oxygen ejected from the pair of slits 11a and 11b intersects between the ground electrode 2 and the honeycomb structure 13, the atmospheric pressure plasma unit 1 and It is necessary to maintain the distance between the honeycomb structure 13 and the honeycomb end face 28 at a predetermined value.
On the other hand, when the large honeycomb structure 13 is processed, the honeycomb end face 28 may have undulations or minute steps depending on the honeycomb structure 13. In this case, in order to achieve uniform plasma processing, it is necessary to adjust the height of the atmospheric pressure plasma unit 1 as needed.
According to this embodiment, by providing the position sensor 80 and the actuator 81, the distance between the atmospheric pressure plasma unit 1 and the honeycomb structure 13 is constant even in the honeycomb structure 13 that is a processing target having undulations and steps. The honeycomb end face 28 can be uniformly processed.

In the plasma processing apparatus of each of the embodiments described above, the honeycomb structure having a hollow structure has been described as the processing body. However, the processing body is not limited to the honeycomb structure, and, for example, the outer peripheral wall of the box-type casing It can be applied to the surface treatment of the surface, the end face of the cylindrical structure and the like.
Moreover, although the mixed gas of nitrogen which is inert gas and dry air was used for supply gas, gas types are not limited to this.
For example, a rare gas such as argon or helium can be used as the inert gas. Similarly, atomic oxygen can be generated by using oxygen instead of air.
Further, the oxygen concentration in the mixed gas is not limited to about 100 ppm. If the oxygen concentration is increased, the number density of atomic oxygen generated in the plasma is improved, but the annihilation rate in the transport field is increased.
Therefore, the oxygen concentration in the mixed gas needs to be appropriately set in consideration of the flow rate of the discharge gas, the transport time, the structure of the treatment body, the discharge power, and the like.
Further, the discharge gas species is not necessarily a mixed gas of an inert gas and oxygen.
For example, if water vapor is used as the discharge gas, OH radicals that are active particles are generated, and if hydrogen is used, atomic hydrogen that is active particles is generated. Since the decay rate of these radical species is almost the same as that of atomic oxygen, the present invention can be applied.

In each of the above embodiments, the high-voltage electrode 3 uses the dielectric 5 in which the conductive layer 6 is embedded. However, it may be a conductor whose surface on at least the gap 7 side is covered with the dielectric 5. As the dielectric material, ceramics such as alumina and zirconia, glass, and resin materials can be used.
The ground electrode 2 can be made of a metal material such as stainless steel, aluminum, or titanium.
Further, the surface of the ground electrode 2 on the gap 7 side may be covered with a dielectric such as ceramic. By doing so, it is possible to obtain the effect of suppressing the corrosion of the metal material accompanying the generation of plasma and the effect of suppressing the generation of metal contamination due to sputtering.
The applied voltage is not limited to an alternating high voltage, but may be any waveform whose polarity changes with time. For example, a bipolar pulse voltage or a sawtooth voltage can be used.

In each of the above embodiments, the ground electrode 2 has a pair of slits 11a and 11b. However, there may be a plurality of slit pairs. In particular, when processing a large processing target, both the high-voltage electrode 3 and the ground electrode 2 are enlarged, and a plurality of pairs of slits 11a and 11b are formed to perform processing at a high speed.
Further, the shapes of the pair of slits 11a and 11b are not necessarily the same. For example, one opening area can be made larger than the other, and for example, the shapes of the curved surfaces can be made different from each other.
Further, the gas ejection holes are not necessarily slits, and may be a plurality of pores formed so that the gas flow of the discharge gas intersects each other.
Further, the slit shape in which a part of the ground electrode 2 in the thickness direction is linear and the other part is curved is not essential, and the whole may be curved in the thickness direction. Moreover, you may form the linear slit in which at least one part of the thickness direction inclined.
In short, at least the pair of gas ejection holes have their tip portions oriented so that the discharge gas ejected from the gas ejection holes intersects between the ground electrode 2 and the honeycomb structure 13 as the treatment body. That's fine.

Further, in each of the above embodiments, the honeycomb structure 13 to be processed is fixedly arranged and the atmospheric pressure plasma unit 1 is driven in the horizontal direction, but the surface treatment is realized by the relative operation of both. Needless to say.
Accordingly, the atmospheric pressure plasma unit 1 may be fixed and the honeycomb structure 13 may be driven.

  1 atmospheric pressure plasma unit, 2, 22, 65 ground electrode, 3 high voltage electrode, 4 housing, 5 dielectric, 6 conductive layer, 7 gap, 8 high voltage power supply, 9a first flow regulator, 9b second flow rate Adjuster, 10 Gas supply port, 11a, 60a, 61a, 11b, 60b, 61b Slit (gas injection hole), 12 Drive mechanism, 13 Honeycomb structure (processing body), 14 Upper ground electrode part (first ground) Electrode portion), 15 lower ground electrode portion (second ground electrode portion), 16 protrusion, 17 curved surface, 18 through hole, 19 curved surface, 20a, 20b slit opening (inlet portion), 23 piping, 23a first Piping section, 23b second piping section, 40 upper curved surface, 41 lower curved surface, 42 peeling point, 25 plasma, 26 gas intersection, 27,72 radical residence field, 28 honeycomb end surface, 30 wide Vertical slit, 31 gas, 32 narrow vertical slit, 33 gas, 50a, 63a first conductive layer portion, 50b, 63b second conductive layer portion, 51a, 51b, 62a, 62b plasma, 70 gas supply source, 71 Gas intersection, 80 position sensor, 81 actuator (adjustment mechanism), 90a curved surface, 90b curved surface.

Claims (9)

A ground electrode and a high-voltage electrode disposed opposite to the ground electrode via a gap, and having a conductive layer having at least a gap-side surface covered with a dielectric, and the gap is subjected to discharge. A gas to be supplied is supplied, and a high voltage is applied to the high-voltage electrode to generate a discharge in the gap near atmospheric pressure, and a discharge gas containing active particles generated by the discharge is formed on the ground electrode. A plasma processing apparatus for treating the surface of the treatment body by ejecting from a gas ejection hole and bringing the active particles into contact with the treatment body facing the ground electrode,
At least one pair of the gas ejection holes is a plasma processing apparatus in which the discharge gas is directed so as to intersect each other between the ground electrode and the processing body.   The conductive layer is composed of a plurality of conductive layer portions that are spaced apart in the plane direction, and each of the conductive layer portions flows from the position facing the discharge gas inlet portion of the gas ejection hole. The plasma processing apparatus of Claim 1 currently formed toward the upstream direction.   The conductive layer is composed of a plurality of conductive layer portions that are spaced apart in the plane direction, and each of the conductive layer portions is provided at the discharge gas inlet portion of one gas ejection hole of each pair of the gas ejection holes. In each of the processing bodies, the gas ejection is continued to a portion where the gas is ejected from the other gas ejection hole by the relative movement of the processing body and the gas ejection port. The plasma processing apparatus according to claim 1, wherein the discharge gas ejected from the hole is supplied.   The gas supply source which supplies gas toward the gas intersection formed by the said discharge gas which passed the said gas ejection hole in the other side through the said process body of the said ground electrode was provided. The plasma processing apparatus according to any one of the above. A position sensor for measuring a distance between the ground electrode and the processing body, provided in an atmospheric pressure plasma unit including the ground electrode, the high-voltage electrode, and a casing housing the high-voltage electrode in cooperation with the ground electrode; ,
A drive mechanism provided in the atmospheric pressure plasma unit and moving the atmospheric pressure plasma unit;
The drive mechanism is configured to move the atmospheric pressure plasma unit along the processing body, and has an adjustment mechanism for moving the atmospheric pressure plasma unit in a direction facing the processing body. Item 5. The plasma processing apparatus according to any one of Items 1 to 4.   The plasma processing apparatus according to claim 1, wherein the pair of gas ejection holes are slits that are close to each other along the downstream side of the discharge gas. The ground electrode is composed of a first ground electrode portion having a through hole through which an intermediate portion passes, and a second ground electrode portion,
The slit is defined by a wall surface of the through hole and a side surface of the second ground electrode, with the second ground electrode portion being fitted into the through hole of the first ground electrode portion. Item 7. The plasma processing apparatus according to Item 6.   The plasma processing apparatus according to claim 1, wherein the discharge gas contains atomic oxygen that is the active particles.   Discharge gas transport time obtained by dividing the distance D (m) between the surface to be treated of the treatment body and the ground electrode by the velocity v (m / s) of the discharge gas ejected from the ejection hole. The plasma processing apparatus according to claim 8, wherein t (s) is 1 millisecond or less.

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