JP6033651B2 - Plasma generator and plasma generator - Google Patents

Description

  The present invention relates to a plasma generator and a plasma generator.

  Plasma generators are used in various applications such as modification of gases such as harmful gases, processing of semiconductor wafers, light sources, and the like.

  Patent Document 1 discloses a plasma generator having a dielectric in which a discharge space (through hole) is formed and a pair of electrodes that are embedded in the dielectric and face each other across the discharge space. In the plasma generator, plasma is generated in the discharge space by applying a voltage between the pair of electrodes.

  Patent Document 2 discloses an ion wind generator (plasma generator) having a flat dielectric and a pair of electrodes provided on the main surface of the dielectric. In this ion wind generator, when a voltage is applied between a pair of electrodes, plasma is generated on the main surface of the dielectric, and consequently, an ion wind that flows along the main surface is generated.

JP 2008-117532 A JP 2008-290711 A

  In the technique of Patent Document 1, when the discharge space is narrowed, the pressure loss of the fluid in the discharge space increases, and the flow velocity decreases. As a result, for example, when the gas is reformed by supplying the gas to the discharge space, the gas processing efficiency decreases.

  Patent Document 2 is a technique relating to control of the flow around the blade, and does not generate plasma in the discharge space. In addition, even if the inner peripheral surface of the discharge space is configured by the main surface of the dielectric of Patent Document 2, the technique of Patent Document 2 can generate plasma only in the vicinity of the main surface of the dielectric. When the discharge space becomes wider, the entire discharge space is not filled with plasma. As a result, for example, when the gas is reformed by supplying the gas to the discharge space, the gas processing efficiency decreases.

  An object of the present invention is to provide a plasma generator and a plasma generator capable of optimizing the distribution and flow of plasma in a discharge space.

  A plasma generator according to a first aspect of the present invention includes a first dielectric portion and a second dielectric portion that face each other across the discharge space in a direction intersecting a flow direction in the discharge space, and the first dielectric portion A first upstream electrode provided on the discharge space side; provided inside the first dielectric portion or on the opposite side of the discharge space; and on the downstream side of the discharge space with respect to the first upstream electrode. The first downstream electrode that is displaced, the second upstream electrode provided on the discharge space side of the second dielectric part, and the inside of the second dielectric part or on the opposite side of the discharge space, A second downstream electrode that is shifted to the downstream side of the discharge space with respect to the second upstream electrode; and the second downstream electrode that is positioned in the discharge space and faces the first downstream electrode and the second downstream electrode. An intermediate electrode.

  Preferably, the plasma generator further includes a third dielectric portion located in the discharge space and having the intermediate electrode embedded therein.

  Preferably, in the third dielectric portion, a thickness of a portion on the first dielectric portion side with respect to the intermediate electrode and a thickness of a portion on the second dielectric portion side with respect to the intermediate electrode are mutually equal. Different.

  Preferably, the third dielectric portion includes a dielectric constant of a portion on the first dielectric portion side with respect to the intermediate electrode, and a dielectric constant of a portion on the second dielectric portion side with respect to the intermediate electrode. Are different from each other.

  Preferably, a distance between the intermediate electrode and the first downstream electrode is different from a distance between the intermediate electrode and the second downstream electrode.

  A plasma generator according to a second aspect of the present invention includes a first dielectric part and a second dielectric part that are opposed to each other across the discharge space in a direction intersecting a flow direction in the discharge space, and A first upstream electrode provided on the discharge space side; provided inside the first dielectric portion or on the opposite side of the discharge space; and on the downstream side of the discharge space with respect to the first upstream electrode. The first downstream electrode that is displaced, the second upstream electrode provided on the discharge space side of the second dielectric part, and the inside of the second dielectric part or on the opposite side of the discharge space, A second downstream electrode that is shifted to the downstream side of the discharge space with respect to the second upstream electrode, a third dielectric portion located in the discharge space, and embedded in the third dielectric portion, A first upstream electrode and an intermediate electrode facing the second upstream electrode.

  A plasma generator according to a third aspect of the present invention includes a plasma generator and a power supply device that applies a voltage to the plasma generator, and the plasma generator intersects a flow direction in a discharge space. A first dielectric part and a second dielectric part that face each other across the discharge space in a direction to perform, a first upstream electrode provided on the discharge space side of the first dielectric part, and an interior of the first dielectric part Alternatively, the first downstream electrode provided on the opposite side of the discharge space and shifted to the downstream side of the discharge space with respect to the first upstream electrode, and provided on the discharge space side of the second dielectric portion. A second downstream electrode provided in the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode. A side electrode, and the first downstream electrode located in the discharge space And an intermediate electrode facing the second downstream electrode, wherein the power supply device is located between the first upstream electrode and the first downstream electrode, between the second upstream electrode and the second electrode. An alternating voltage is applied between the downstream electrode, between the first downstream electrode and the intermediate electrode, and between the second downstream electrode and the intermediate electrode.

  Preferably, in the power supply device, the first upstream electrode, the second upstream electrode, and the intermediate electrode have the same potential, and the first downstream electrode and the second downstream electrode have the same potential.

  Preferably, the power supply device also applies an alternating voltage between the first downstream electrode and the second downstream electrode.

  According to said structure, the distribution and flow of the plasma in discharge space can be optimized.

FIG. 1A is a schematic perspective view showing the appearance of the plasma generator according to the first embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view taken along line Ib-Ib in FIG. The cross-sectional schematic of the plasma generator which concerns on the 2nd Embodiment of this invention. Sectional schematic of the plasma generator which concerns on the 3rd Embodiment of this invention. The cross-sectional schematic of the plasma generator which concerns on the 4th Embodiment of this invention. Sectional schematic of the plasma generator which concerns on the 5th Embodiment of this invention. Sectional schematic of the plasma generator which concerns on the 6th Embodiment of this invention.

  Hereinafter, a plasma generator and a plasma generator according to a plurality of embodiments of the present invention will be described with reference to the drawings. In the description of each embodiment, the same or similar symbols are used for configurations that are the same as or similar to the configurations of the already described embodiments, and illustrations and descriptions may be omitted.

  For the same or similar structures, numbers such as “first” and “second” are added to the beginning of the name, and capital letters such as “A” and “B” are added to the reference numerals. These numbers and alphabets may be omitted.

<First Embodiment>
FIG. 1A is a schematic perspective view showing the appearance of the plasma generator 1 according to the first embodiment of the present invention, and FIG. 1B shows a plasma generator 51 including the plasma generator 1. FIG. 2 is a schematic sectional view taken along line Ib-Ib in FIG.

  In addition, the plasma generator 1 may be configured such that any direction is upward or downward. Hereinafter, a Cartesian coordinate system xyz may be defined and a direction may be specified with reference to xyz.

  The plasma generator 51 includes a plasma generator 1, a power supply device 53 (FIG. 1B) that applies a voltage to the plasma generator 1 to generate plasma in the plasma generator 1, and a control that controls the power supply device 53. Device 55 (FIG. 1B).

  The plasma generator 1 has a dielectric 3 and a plurality of electrodes provided on the dielectric 3. The plurality of electrodes include a first upstream electrode 5A and a second upstream electrode 5B that are used for generating an ion wind, a first downstream electrode 7A that is used for generating an ion wind and a plasma, and a second downstream side. An electrode 7B (FIG. 1B) and an intermediate electrode 9 (FIG. 1B) used for plasma generation. In addition to this, the plasma generator 1 may have wiring or the like for connecting each electrode and the power supply device 53.

  A through-hole penetrating in the x direction is formed in the dielectric 3, and the through-hole serves as a discharge space 11 for generating plasma by discharge. The discharge space 11 is also used to generate an ion wind that flows to one side of the penetration direction (positive side in the x direction). The discharge space 11 is branched in the thickness direction (z direction) on the downstream side (positive side in the x direction) of the ion wind.

  From another viewpoint, the dielectric 3 is positioned in the discharge space 11 with the first dielectric portion 15A and the second dielectric portion 15B facing each other across the discharge space 11 in the direction intersecting the flow direction in the discharge space 11. And a third dielectric portion 15C. The downstream portion of the discharge space 11 is partitioned into a first branch path 13A and a second branch path 13B by a third dielectric portion 15C.

  The outer shape of the dielectric 3 and the shape of the discharge space 11 may be set as appropriate. In the example of FIG. 1, the outer shape of the dielectric 3 is a cuboid, the shape of the discharge space 11 (the shape when the third dielectric portion 15C is not taken into consideration) is a cuboid, and the shape of each branch path 13 is It is a rectangular parallelepiped. From another point of view, the first dielectric portion 15A, the second dielectric portion 15B, and the third dielectric portion 15C each have a flat plate shape with a constant thickness, and are arranged in parallel to each other.

  The dielectric 3 has, for example, a plane-symmetric shape in the z direction. Accordingly, the third dielectric portion 15C is located in the center of the discharge space 11 in the z direction, and the shape and size of the first branch path 13A and the second branch path 13B are the same.

  The dielectric 3 may be formed of an inorganic insulator or an organic insulator. Examples of the inorganic insulator include ceramic and glass. Examples of the ceramic include an aluminum oxide sintered body (alumina ceramic), a glass ceramic sintered body (glass ceramic), a mullite sintered body, an aluminum nitride sintered body, a cordierite sintered body, and a silicon carbide sintered body. Examples include ligation. Examples of the organic insulator include polyimide, epoxy, and rubber. The entire dielectric 3 may be integrally formed of the same material, or members formed of different materials may be fixed to each other.

  Each of the upstream electrode 5, the downstream electrode 7, and the intermediate electrode 9 is formed in, for example, a flat plate shape (layer shape) having a constant thickness. The planar shape is, for example, a rectangle. The width of these electrodes (the length in the y direction) is, for example, equal to the width of the discharge space 11 and the same.

  The first upstream electrode 5A is provided on the discharge space 11 side of the first dielectric portion 15A. More specifically, for example, the first upstream electrode 5A is superimposed on the surface of the first dielectric portion 15A on the discharge space 11 side. Therefore, the upstream electrode 5 is exposed to the discharge space 11. Similarly, the second upstream electrode 5B is provided on the discharge space 11 side of the second dielectric portion 15B and is exposed to the discharge space 11. The shapes and positions of the first upstream electrode 5A and the second upstream electrode 5B are, for example, plane-symmetric in the z direction.

  The first downstream electrode 7A is embedded in the first dielectric portion 15A and is shifted to the downstream side with respect to the first upstream electrode 5A. Similarly, the second downstream electrode 7B is embedded in the second dielectric portion 15B and is shifted to the downstream side with respect to the second upstream electrode 5B. The shapes and positions of the first downstream electrode 7A and the second downstream electrode 7B are, for example, plane-symmetric in the z direction.

  In the present application, when the downstream electrode is shifted to the downstream side with respect to the upstream electrode, the downstream electrode may have a portion located on the downstream side of the downstream edge of the upstream electrode. I shall do it. In other words, the downstream electrode 7 may be adjacent so that the upstream portion thereof does not overlap the upstream electrode 5 in plan view (as viewed in the z direction), or downstream of the upstream electrode 5. It may overlap with a part of the side or all of the upstream electrode, or may be separated from the upstream electrode to the downstream side.

  For example, the downstream electrode 7 is arranged in parallel to the surface of the first dielectric portion 15A or the second dielectric portion 15B on the discharge space 11 side. Moreover, the downstream electrode 7 is formed larger than the upstream electrode 5 in the flow direction (x direction), for example.

  The intermediate electrode 9 is embedded in the third dielectric portion 15C. In other words, the intermediate electrode 9 is located in the discharge space 11. The intermediate electrode 9 is located at the center of the third dielectric portion 15C, for example. Therefore, in the third dielectric portion 15C, the thickness of the portion on the first dielectric portion 15A side with respect to the intermediate electrode 9 and the thickness of the portion on the second dielectric portion 15B side with respect to the intermediate electrode 9 are the same. .

  The intermediate electrode 9 is opposed to the downstream electrode 7 across the branch path 13. The distance between the intermediate electrode 9 and the first downstream electrode 7A and the distance between the intermediate electrode 9 and the second downstream electrode 7B are, for example, the same. Moreover, the magnitude | size of the flow direction (x direction) of the intermediate electrode 9 is smaller than the downstream electrode 7, for example. The intermediate electrode 9 faces, for example, the downstream portion of the downstream electrode 7.

  The upstream electrode 5, the downstream electrode 7, and the intermediate electrode 9 are formed of a conductive material such as metal. Examples of the metal include tungsten, molybdenum, manganese, copper, silver, gold, palladium, platinum, nickel, cobalt, and alloys containing these as a main component.

  The power supply device 53 includes the first upstream electrode 5A and the first downstream electrode 7A, the second upstream electrode 5B and the second downstream electrode 7B, the first downstream electrode 7A and the intermediate electrode 9 And an AC voltage is applied between the second downstream electrode 7 </ b> B and the intermediate electrode 9. Preferably, the first upstream electrode 5A, the second upstream electrode 5B, and the intermediate electrode 9 have the same potential, and the first downstream electrode 7A and the second downstream electrode 7B have the same potential.

  The AC voltage applied by the power supply device 53 may be a voltage whose potential is continuously changed, represented by a sine wave or the like, or a pulse-like voltage whose potential change is discontinuous. . The alternating voltage may be one in which the potential varies with respect to the reference potential in both the pair of electrodes, or one of the pair of electrodes is connected to the reference potential, and the potential is only in the other. May vary. The fluctuation of the potential may be positive and negative with respect to the reference potential, or may be only positive and negative with respect to the reference potential.

  The control device 55 controls, for example, ON / OFF of voltage application by the power supply device 53 and voltage value and frequency in voltage application by the power supply device 53.

  Note that the dimensions of each part of the dielectric 3, the upstream electrode 5, the downstream electrode 7 and the intermediate electrode 9, the positions such as the embedding depth of various electrodes, and the magnitude and frequency of the AC voltage are determined by the plasma generator 51 (plasma It may be set appropriately according to various circumstances such as the technical field to which the generator 1) is applied and the required plasma amount.

  The manufacturing method of the plasma generator 1 may be a manufacturing method similar to the manufacturing method of a multilayer substrate, for example. Taking the case where the dielectric 3 is composed of a ceramic sintered body obtained by laminating and firing a plurality of ceramic green sheets in the height direction (z direction), the following is taken as an example.

First, a plurality of ceramic green sheets are prepared. The ceramic green sheet is formed, for example, by forming a slurry into a sheet shape by a doctor blade method, a calender roll method, or the like. The slurry is prepared by adding and mixing an appropriate organic solvent and solvent to the raw material powder. Taking an alumina ceramic as an example, the raw material powder is alumina (Al ₂ O ₃ ), silica (SiO ₂ ), calcia (CaO), magnesia (MgO), or the like.

  Next, a space that becomes the discharge space 11 is formed in some ceramic green sheets among the plurality of ceramic green sheets by punching or laser processing. Moreover, the conductive paste used as various electrodes is provided in some of the ceramic green sheets. For example, the first dielectric portion 15A is formed by laminating two or more ceramic green sheets, and a conductive paste serving as the downstream electrode 7 is provided on the surface to be superimposed.

  The conductive paste is produced, for example, by adding and mixing an organic solvent and an organic binder to a metal powder such as tungsten, molybdenum, copper, or silver. In the conductive paste, a dispersant, a plasticizer, or the like may be added as necessary. Mixing is performed by kneading means such as a ball mill, a three-roll mill, or a planetary mixer. The conductive paste is printed and applied to the ceramic green sheet by using a printing means such as a screen printing method.

  Then, a plurality of ceramic green sheets are laminated, and the conductive paste and the ceramic green sheets are simultaneously fired. Thereby, the dielectric 3 in which various electrodes are embedded or formed on the surface and the discharge space 11 is formed, that is, the plasma generator 1 is formed.

  Below, the effect | action of the plasma generator 1 is demonstrated.

The plasma generator 1 is used in a state where the discharge space is filled with air, a gas to be treated, or other appropriate gas. Note that the gas to be treated is, for example, nitrogen oxide (NOx), chlorofluorocarbon, CO ₂ , volatile organic solvent (VOC), or air containing these. Automobile exhaust gas is well known as a gas containing nitrogen oxides (NOx).

  When a voltage is applied to the first upstream electrode 5A and the first downstream electrode 7A, an electric field is formed in the vicinity of the surface of the first dielectric portion 15A on the discharge space 11 side. When the electric field strength exceeds a predetermined discharge start electric field strength, dielectric barrier discharge is started and plasma is generated.

  Electrons or ions in the plasma move due to the electric field formed by the first upstream electrode 5A and the first downstream electrode 7A. Neutral molecules also move with electrons or ions. Thereby, an ionic wind flowing in the discharge space 11 in the penetration direction is induced.

  More specifically, since the first upstream electrode 5A is exposed and the first downstream electrode 7A is embedded in the dielectric 3, the first upstream electrode 5A is moved to the first downstream electrode 7A side. Dielectric barrier discharge occurs, and as indicated by an arrow y1, ion wind flows from the first upstream electrode 5A side to the first downstream electrode 7A side.

  Similarly, when a voltage is applied to the second upstream electrode 5B and the second downstream electrode 7B, as shown by an arrow y2, in the vicinity of the surface on the discharge space 11 side of the second dielectric portion 15B, the second upstream side An ion wind flowing from the electrode 5B side to the second downstream electrode 7B side is generated.

  In addition, when a voltage is applied to the first downstream electrode 7A and the intermediate electrode 9, the opposed region between the first downstream electrode 7A and the intermediate electrode 9 (in this embodiment, the first branch path 13A and the dotted line r1). An electric field is formed at (approximately coincident). When the electric field strength exceeds a predetermined discharge start electric field strength, dielectric barrier discharge is started and plasma is generated. Since the first downstream electrode 7A and the intermediate electrode 9 are opposed to each other across the first branch path 13A, plasma is generated over the entire height direction (z direction) in the first branch path 13A. To charge.

  Similarly, when a voltage is applied to the second downstream electrode 7B and the intermediate electrode 9, the opposing region of the second downstream electrode 7B and the intermediate electrode 9 (in this embodiment, the second branch path 13B and the dotted line r2). Plasma is generated at substantially the same).

  As described above, in the present embodiment, the plasma generator 1 includes the first dielectric portion 15A and the second dielectric portion 15B facing each other with the discharge space 11 in the direction intersecting the flow direction in the discharge space 11, and the first dielectric portion 15B. The first upstream electrode 5A provided on the discharge space 11 side of the dielectric portion 15A, and the first downstream side provided in the first dielectric portion 15A and shifted to the downstream side with respect to the first upstream electrode 5A The electrode 7A, the second upstream electrode 5B provided on the discharge space 11 side of the second dielectric portion 15B, and the second dielectric portion 15B are provided in the inside of the second dielectric portion 15B, and shifted to the downstream side with respect to the second upstream electrode 5B. A second downstream electrode 7B, and an intermediate electrode 9 located in the discharge space 11 and facing the first downstream electrode 7A and the second downstream electrode 7B.

  Therefore, even if the discharge space 11 is large, the discharge space 11 can be filled with plasma by the discharge of the downstream electrode 7 and the intermediate electrode 9. On the other hand, even if the discharge space 11 is small, the upstream electrode 5 In addition, the downstream electrode 7 can generate ion wind in the vicinity of the inner peripheral surface of the discharge space 11 to compensate for a decrease in flow velocity due to pressure loss. That is, it is possible to cause the plasma to flow while being suitably filled in discharge spaces of various sizes. As a result, for example, the design freedom of the plasma generator 1 can be improved, or gas can be efficiently plasma-treated in the discharge space 11. Moreover, since the downstream electrode 7 is used for both the generation of ion wind and the generation of plasma over the entire branch path 13, the configuration is simple.

<Second Embodiment>
FIG. 2 is a cross-sectional view similar to FIG. 1A showing the configuration of the plasma generator 251 according to the second embodiment.

  The plasma generator 201 of the plasma generator 251 is different from the plasma generator 1 of the first embodiment only in the configuration of the third dielectric part 215C. Specifically, it is as follows.

  The intermediate electrode 9 is not located at the center of the third dielectric portion 215C in the z direction, but is biased toward the second dielectric portion 15B. That is, in the third dielectric part 215C, the second dielectric layer 216b on the second dielectric part 15B side with respect to the intermediate electrode 9 is the first dielectric layer 216a on the first dielectric part 15A side with respect to the intermediate electrode 9. On the other hand, it is thinner.

  Note that the position of the intermediate electrode 9 with respect to the first downstream electrode 7A and the second downstream electrode 7B is, for example, biased toward the second downstream electrode 7B by the above-described deviation. However, the intermediate electrode 9 may be positioned between the first downstream electrode 7A and the second downstream electrode 7B. In this case, corresponding to the fact that the second dielectric layer 216b is thinner than the first dielectric layer 216a, the second branch path 213B is larger in the thickness direction (z direction) than the first branch path 213A.

  Since the second dielectric layer 216b is thinner than the first dielectric layer 216a, the second branch path 213B has a stronger plasma or a lower voltage than the first branch path 213A. Arise.

  Therefore, for example, in the case where the positive side in the z direction is vertically upward, among the gas to be reformed, a light component that is difficult to be reformed flows into the second branch 213B, and a heavy component that is easily reformed and a heavy component is the first branch. In the case of flowing into 213A, the entire gas can be efficiently reformed.

In the third dielectric portion 215C of the present embodiment, the dielectric constant of the second dielectric layer 216b is higher than the dielectric constant of the first dielectric layer 216a. For example, as the material of the third dielectric portion 215C, silica (SiO ₂ , relative dielectric constant: 3-4), alumina (Al ₂ O ₃ , relative dielectric constant: 8-11), titanium dioxide (TiO ₂ , relative dielectric) Rate: 83-183), barium titanate (BaTiO ₃ , relative dielectric constant: 1200-3000), strontium titanate (SrTiO ₃ , relative dielectric constant: 300), calcium titanate (CaTiO ₃ , relative dielectric constant: 200) And barium strontium titanate (Ba _1-x Sr _x TiO ₃ , relative dielectric constant: 800-1500) and barium calcium titanate (Ba _1-x Ca _x TiO ₃ , relative dielectric constant: 600-1200). One of these may be the material of the first dielectric layer 216a, and the other one having a higher dielectric constant than the material may be the second dielectric layer 216b. It may be a fee.

  By setting the dielectric constant in this way, in the second branch 213B, the plasma becomes stronger or discharge occurs at a lower voltage than in the first branch 213A. Therefore, an effect similar to the effect due to the difference in thickness between the first dielectric layer 216a and the second dielectric layer 216b described above can be obtained.

  Note that the method of making the dielectric constants different from each other, for example, compared to the method of making the thicknesses different from each other, for example, the distance between the intermediate electrode 9 and the downstream electrode 7 and the first branch 213A and the second branch 213B. There is an advantage that the intensity of the plasma can be adjusted independently of the magnitude relationship. On the other hand, the method of making the thicknesses different from each other has an advantage that it is not necessary to prepare two kinds of materials, for example, compared to the method of making the dielectric constants different from each other.

<Third Embodiment>
FIG. 3 is a cross-sectional view similar to FIG. 1A, showing the configuration of the plasma generator 351 according to the third embodiment.

  The plasma generator 301 of the plasma generator 351 is different from the plasma generator 1 of the first embodiment only in the position of the third dielectric portion 15C (intermediate electrode 9). Specifically, it is as follows.

  The third dielectric portion 15C is arranged to be biased toward the second dielectric portion 15B in the discharge space 311. Therefore, the distance between the intermediate electrode 9 and the second downstream electrode 7B is shorter than the distance between the intermediate electrode 9 and the first downstream electrode 7A.

  Therefore, in the second branch path 313B, the plasma becomes stronger or discharge occurs at a lower voltage than in the first branch path 313A. Accordingly, the same effects as those of the second embodiment are achieved. By generating relatively strong plasma in the relatively narrow second branch 313B, it is expected that the gas reforming process is performed more intensively in the second branch 313B.

<Fourth Embodiment>
FIG. 4 is a cross-sectional view similar to FIG. 1A showing the configuration of the plasma generator 451 according to the fourth embodiment.

  The plasma generator 401 of the plasma generator 451 is different from the plasma generator 1 of the first embodiment only in that the third dielectric portion 15C is not provided and the intermediate electrode 9 is exposed to the discharge space 411. To do.

  Thus, even when the intermediate electrode 9 is exposed to the discharge space 411, the downstream electrode 7 is embedded in the first dielectric portion 15A or the second dielectric portion 15B. Dielectric barrier discharge that is easier to control than corona discharge or the like occurs between the side electrodes 7.

  In the present embodiment, since the upstream electrode 5 and the intermediate electrode 9 are at the same potential, no discharge occurs between them. Further, even when the upstream electrode 5 and the intermediate electrode 9 are at different potentials, the distance between the upstream electrode 5 and the intermediate electrode 9 is made longer than the distance between the downstream electrode 7 and the intermediate electrode 9, By making the voltage applied between the upstream electrode 5 and the intermediate electrode 9 lower than the voltage applied between the downstream electrode 7 and the intermediate electrode 9, the downstream electrode 7 and the intermediate electrode 9. While the dielectric barrier discharge is generated between the upper electrode 5 and the intermediate electrode 9, the corona discharge or the like can be suppressed. However, a discharge may be generated between the upstream electrode 5 and the intermediate electrode 9.

  As a method of providing the intermediate electrode 9 as in the present embodiment, for example, the intermediate electrode 9 is configured by a sheet metal having a width larger than the width of the discharge space 411 (size in the y direction), and the first dielectric portion 15A. And both ends of the intermediate electrode 9 may be sandwiched between a plurality of ceramic green sheets laminated between the second dielectric portion 15B and the second dielectric portion 15B.

  As described above, also in the present embodiment, the same effects as those in the first embodiment are exhibited. In addition, since the third dielectric portion 15C is not provided, the discharge space 411 can be widened as compared with the first embodiment. Further, in the second embodiment, it has been described that the thinner the dielectric layer covering the intermediate electrode 9 is, the stronger the plasma is or the discharge is generated at a low voltage. In the present embodiment, the dielectric covering the intermediate electrode 9 is described. Since the layer is not provided, the plasma can be further strengthened or discharge can be generated at a low voltage.

<Fifth Embodiment>
FIG. 5 is a cross-sectional view similar to FIG. 1A showing the configuration of the plasma generator 551 according to the fifth embodiment.

  The plasma generator 1 of the plasma generator 551 is the same as the plasma generator 1 of the first embodiment, and the plasma generator 551 has only the potential (configuration of the power supply device) applied to each electrode in the first embodiment. This is different from the plasma generator 51 of the embodiment. Specifically, it is as follows.

  The plasma generator 551 includes a first power supply device 53A that applies a voltage between the first upstream electrode 5A and the first downstream electrode 7A, and a second upstream electrode 5B and a second downstream electrode 7B. And a second power supply device 53B for applying a voltage to the power supply.

  Accordingly, as in the first embodiment, as indicated by arrows y1 and y2, ion wind is generated on the surfaces of the first dielectric portion 15A and the second dielectric portion 15B on the discharge space 11 side.

  The first power supply device 53A and the second power supply device 53B are synchronized, and different potentials are applied to the first downstream electrode 7A and the second downstream electrode 7B. That is, an AC voltage is also applied between the first downstream electrode 7A and the second downstream electrode 7B.

  More specifically, for example, the first upstream electrode 5A, the second upstream electrode 5B, and the intermediate electrode 9 are set to the same potential as in the first embodiment. Further, for example, a reference potential is applied to the first upstream electrode 5A, the second upstream electrode 5B, and the intermediate electrode 9, and a varying potential is applied to the first downstream electrode 7A and the second downstream electrode 7B.

  The variable potentials applied to the first downstream electrode 7A and the second downstream electrode 7B have, for example, the same frequency. The varying potentials applied to these electrodes have opposite polarities (positive and negative), or the same polarity and different amplitudes. As a result, a voltage is applied between the first downstream electrode 7A and the second downstream electrode 7B.

  In addition, the method of reversing the polarity of the fluctuation potential may be realized by shifting the phase of the fluctuation potential in which the potential fluctuates in both positive and negative directions by 180 °, or one fluctuation potential fluctuates only in the positive direction. The other fluctuation potential may be realized by changing only in the negative.

  As described above, when a voltage is applied between the first downstream electrode 7A and the second downstream electrode 7B, the first downstream electrode 7A and the second downstream electrode 7B indicated by the dotted line r3 are shown. Dielectric barrier discharge occurs in the region that is the opposite region and where the third dielectric portion 15C is not disposed. That is, in addition to the generation of ion wind and the generation of plasma as in the first embodiment, plasma is also generated between the first downstream electrode 7A and the second downstream electrode 7B. As a result, the plasma generation region can be expanded and the plasma generation mode can be diversified.

  The first embodiment has an advantage that the configuration of the power supply unit is simpler than the fifth embodiment, and the plasma generator can be configured at low cost.

  In the fifth embodiment, the first power supply device 53A and the second power supply device 53B may be regarded as one power supply device 554 as a whole. Further, in place of the power supply device 554, a power supply device that supplies three-phase AC power to the group of the upstream electrode 5 and the intermediate electrode 9, the first downstream electrode 7A, and the second downstream electrode 7B is provided. Also good.

<Sixth Embodiment>
FIG. 6 is a cross-sectional view similar to FIG. 1A showing the configuration of the plasma generator 651 according to the sixth embodiment.

  In the first embodiment, plasma is generated between the downstream electrode 7 and the intermediate electrode 9, whereas in this embodiment, plasma is generated between the upstream electrode 5 and the intermediate electrode 9. . Specifically, it is as follows.

  The third dielectric portion 15C is located between the first upstream electrode 5A and the second upstream electrode 5B. Therefore, the intermediate electrode 9 embedded in the third dielectric portion 15C faces the first upstream electrode 5A and, on the opposite side, faces the second upstream electrode 5B. Note that the third dielectric portion 15C (intermediate electrode 9) is not positioned between, for example, the first downstream electrode 7A and the second downstream electrode 7B.

  The power supply device 53 applies a voltage between the upstream electrode 5 and the downstream electrode 7 as in the first embodiment. Further, unlike the first embodiment, the power supply device 53 applies a voltage between the upstream electrode 5 and the intermediate electrode 9.

  More specifically, for example, as in the first embodiment, the first upstream electrode 5A and the second upstream electrode 5B have the same potential, and the first downstream electrode 7A and the second downstream electrode 7B. Are set to the same potential, and a voltage is applied between these groups. On the other hand, unlike the first embodiment, the intermediate electrode 9 is set to the same potential as the downstream electrode 7, whereby a voltage is applied to the upstream electrode 5.

  Also in the present embodiment, as in the first embodiment, while generating plasma over the entire z direction of the discharge space 611, an ion wind is generated on the inner peripheral surface of the discharge space 11, and 2 An electrode common to the functions of the seeds (in this embodiment, the upstream electrode 5) can be used.

  The ion wind becomes stronger as the downstream electrode 7 becomes larger in the flow direction (x direction), while the size of the upstream electrode 5 in the x direction does not significantly affect the strength of the ion wind. In addition, the plasma generated between the intermediate electrode 9 and the electrode (upstream electrode 5 or downstream electrode 7) facing the intermediate electrode 9 is more likely to fill the discharge space as the facing area of the electrode increases.

  Accordingly, in the first to fifth embodiments, the upstream electrode 5 is made smaller in the x direction while the downstream electrode 7 is made larger in the x direction than in the sixth embodiment. It is considered that the ion wind can be strengthened and the plasma can be easily filled while downsizing in the x direction.

  On the other hand, in the sixth embodiment, for example, ions or electrons are filled in the height direction (z direction) of the discharge space 611 on the upstream electrode 5, and the ions or electrons are filled with the upstream electrode 5 and the downstream side. Since it moves due to the electric field formed by the electrode 7, it is expected that the flow will have a thickness.

  In the plasma generator 601 of the sixth embodiment, the downstream electrode 7 is not embedded in the first dielectric part 615A or the second dielectric part 615B, but the discharge of the first dielectric part 615A or the second dielectric part 615B. The plasma generator 1 of the first embodiment is also different in that it is provided on the side opposite to the space 611.

  Even when the downstream electrode 7 is provided in this way, plasma or ion wind is generated in the discharge space 611 as in the case where the downstream electrode 7 is embedded.

  When the downstream electrode 7 is provided in this way, on the surface opposite to the discharge space 611, ion wind from the downstream electrode 7 to the upstream electrode 5 (the ion wind in the discharge space 611 and Occurs in the opposite direction). The ion wind may not be used or may be used as appropriate.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  The first to sixth embodiments may be appropriately combined. For example, when the intermediate electrode is embedded in the third dielectric portion, the two dielectric layers (216a, 216b) in the second embodiment (FIG. 2) have different thicknesses, and the two dielectric layers in the same embodiment Features with different dielectric constants of layers, features with different distances between the intermediate electrode and the two downstream electrodes in the third embodiment (FIG. 3), and first downstream in the fifth embodiment (FIG. 5) The features for generating plasma between the side electrode and the second downstream electrode may be appropriately selected and combined with two or more features from these, or the upstream electrode and the intermediate electrode of the sixth embodiment may be combined. It may be applied to a mode in which plasma is generated between. In addition, for example, the feature that the third dielectric portion that covers the intermediate electrode of the fourth embodiment (FIG. 4) is not provided is that the intermediate electrode of the third embodiment (FIG. 3) and the two downstream electrodes are It may be combined with the feature that the distances are different from each other and / or the feature that generates plasma between the first downstream electrode and the second downstream electrode of the fifth embodiment (FIG. 5). The present invention may be applied to a mode in which plasma is generated between the upstream electrode and the intermediate electrode in the embodiment. Further, for example, in the aspect in which the intermediate electrode faces the downstream electrode as in the first to fifth embodiments, the downstream electrode is discharged from the first dielectric part or the second dielectric part as in the sixth embodiment. In the aspect in which the intermediate electrode faces the upstream electrode as in the sixth embodiment, the downstream electrode is the first as in the first to fifth embodiments. It may be embedded in the dielectric part or the second dielectric part.

  The shape of the dielectric is not limited to that exemplified in the embodiment.

  For example, the dielectric may be formed so as to expand in the height direction (z direction) toward the upstream side at the entrance portion of the discharge space. In this case, inflow of the fluid to be processed into the discharge space can be facilitated. The upstream electrode may be provided on the inner peripheral surface that expands. In this case, since the distance between the first upstream electrode and the second upstream electrode is increased, it is possible to suppress the occurrence of corona discharge or the like between these electrodes even when different potentials are applied to these electrodes.

  Further, for example, in the embodiment, the third dielectric portion 15C and / or the intermediate electrode 9 partition the discharge space only on the downstream side or only on the upstream side, but the third dielectric portion and / or the intermediate electrode 9 The discharge space may be partitioned over the entire flow direction (x direction).

  Further, the dielectric is not limited to one made of a ceramic multilayer substrate. For example, the dielectric may be formed by filling an insulating material in a mold.

  The positions of the various electrodes with respect to the dielectric may be set as appropriate.

  For example, the upstream electrode (or downstream electrode) is not overlaid on the surface of the dielectric, but is fitted into a recess formed on the surface of the dielectric, and the surface is flush with the top surface of the dielectric. It may be. In this case, the channel resistance can be reduced. Further, the upstream electrode may be prevented from being exposed to the discharge space by being coated with a dielectric material (covered with a thin film).

  For example, the intermediate electrode may be provided on the surface of the third dielectric portion on the first dielectric portion side or on the surface of the second dielectric portion side. Also in this case, the plasma intensity or the discharge start voltage can be made different between the first branch path and the second branch path.

  The various electrodes are not limited to the shapes exemplified in the embodiment such as a rectangular flat plate shape. Moreover, the magnitude | size etc. may be set suitably.

  For example, the upstream electrode may have a shape having almost no area in the flow direction (x direction). For example, a step where the upstream side is higher than the downstream side may be provided on the surface of the first dielectric portion or the second dielectric portion on the discharge space side, and an upstream electrode may be provided on the surface facing the downstream side of the step. In this case, the exposed area of the upstream electrode can be increased while reducing the size of the plasma generator in the flow direction.

  Further, for example, the downstream electrode may be formed so as to be longer in the flow direction (x direction) of the ion wind toward the side (end portion side in the y direction). In this case, as described above, the ion wind becomes stronger as the downstream electrode becomes longer in the flow direction, so that the pressure loss on the side surface of the discharge space can be compensated. Further, in accordance with the planar shape of the downstream electrode, the planar shape of the intermediate electrode may be lengthened in the flow direction toward the side.

  Further, for example, the downstream electrode may have a shape and / or arrangement that approaches the discharge space toward the downstream side. More specifically, for example, the downstream electrode may have a step shape or a flat plate shape inclined in the flow direction (x direction). In this case, since the distance to the upstream electrode can be made uniform over the entire downstream electrode, the intensity of the ion wind is made uniform on the downstream electrode.

  For example, the intermediate electrode may face both the upstream electrode and the downstream electrode. In this case, as in the embodiment, the intermediate electrode may be applied with a voltage between only one of the upstream electrode and the downstream electrode to contribute to the generation of plasma. A voltage may be applied during this period to contribute to the generation of plasma.

  For example, the intermediate electrode facing only the downstream electrode may have a width facing not only the downstream portion of the downstream electrode but also the entire downstream electrode. In this case, the distance between the intermediate electrode and the upstream electrode is closer than in the case where the intermediate electrode faces only the downstream portion of the downstream electrode. At this time, as in the embodiment, the intermediate electrode may be configured not to generate plasma between the upstream electrode and the like by being set to the same potential as the upstream electrode. An electric potential may be applied so as to generate plasma even in the meantime.

  Further, electrodes other than those exemplified in the embodiment may be provided on the dielectric.

  For example, a DC electrode to which a DC voltage is applied without forming a closed loop (only one of the positive terminal and the negative terminal of the DC power supply device is connected) may be provided on the downstream side of the downstream electrode. . In this case, ions or electrons can be attracted by the electric field formed by the DC electrode, and the ion wind can be accelerated.

  Further, for example, an electrode that generates an ion wind with the intermediate electrode and separated from the intermediate electrode by a dielectric may be provided on the downstream side of the intermediate electrode (FIG. 4) exposed to the discharge space.

  The plasma generator may not have a symmetric configuration or shape in the height direction (z direction). For example, the first upstream electrode and the second upstream electrode may have different shapes or sizes, and the first downstream electrode and the second downstream electrode have different shapes, sizes, or embedding depths. It may be.

  Combinations of potentials applied to various electrodes are not limited to those exemplified in the embodiments.

  For example, as already mentioned a little, different potentials are applied to the upstream electrode, the downstream electrode and the intermediate electrode, both between the intermediate electrode and the upstream electrode, and between the intermediate electrode and the downstream electrode. Plasma may be generated.

  More specifically, for example, a three-phase AC electrode may be supplied to the upstream electrode, the downstream electrode, and the intermediate electrode. Further, for example, a reference potential may be applied to any one of the upstream electrode, the downstream electrode, and the intermediate electrode, and a variable potential having a reverse polarity may be applied to the other two electrodes. An example of a method for reversing the polarities of two fluctuation potentials has already been described in the fifth embodiment.

  Applications of the plasma generator and the plasma generator of the present invention are not limited to gas reforming. For example, the plasma generator of the present invention can constitute a plasma supply apparatus that can supply plasma in a small and efficient manner during processing of a semiconductor wafer or the like.

  DESCRIPTION OF SYMBOLS 1 ... Plasma generator, 5 ... Upstream electrode, 7 ... Downstream electrode, 9 ... Intermediate electrode, 11 ... Discharge space, 15A ... 1st dielectric part, 15B ... 2nd dielectric part.

Claims (9)

A first dielectric portion and a second dielectric portion facing each other across the discharge space in a direction intersecting a flow direction in the discharge space;
A first upstream electrode provided on the discharge space side of the first dielectric part;
A first downstream electrode provided inside the first dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the first upstream electrode;
A second upstream electrode provided on the discharge space side of the second dielectric part;
A second downstream electrode provided inside the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode;
A third dielectric portion located in the discharge space;
An intermediate electrode embedded in the third dielectric portion and facing the first downstream electrode and the second downstream electrode;
And have a,
The third dielectric portion is a plasma generator in which a thickness of a portion on the first dielectric portion side with respect to the intermediate electrode and a thickness of a portion on the second dielectric portion side with respect to the intermediate electrode are different from each other. . A first dielectric portion and a second dielectric portion facing each other across the discharge space in a direction intersecting a flow direction in the discharge space;
A first upstream electrode provided on the discharge space side of the first dielectric part;
A first downstream electrode provided inside the first dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the first upstream electrode;
A second upstream electrode provided on the discharge space side of the second dielectric part;
A second downstream electrode provided inside the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode;
A third dielectric portion located in the discharge space;
An intermediate electrode embedded in the third dielectric portion and facing the first downstream electrode and the second downstream electrode;
Have
In the third dielectric portion, a dielectric constant of a portion on the first dielectric portion side with respect to the intermediate electrode is different from a dielectric constant of a portion on the second dielectric portion side with respect to the intermediate electrode.
Flop plasma generator. The plasma generator according to claim 1 or 2 , wherein a distance between the intermediate electrode and the first downstream electrode is different from a distance between the intermediate electrode and the second downstream electrode. A first dielectric portion and a second dielectric portion facing each other across the discharge space in a direction intersecting a flow direction in the discharge space;
A first upstream electrode provided on the discharge space side of the first dielectric part;
A first downstream electrode provided inside the first dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the first upstream electrode;
A second upstream electrode provided on the discharge space side of the second dielectric part;
A second downstream electrode provided inside the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode;
A third dielectric portion located in the discharge space;
An intermediate electrode embedded in the third dielectric portion and facing the first upstream electrode and the second upstream electrode;
And have a,
The third dielectric portion is a plasma generator in which a thickness of a portion on the first dielectric portion side with respect to the intermediate electrode and a thickness of a portion on the second dielectric portion side with respect to the intermediate electrode are different from each other. . A first dielectric portion and a second dielectric portion facing each other across the discharge space in a direction intersecting a flow direction in the discharge space;
A first upstream electrode provided on the discharge space side of the first dielectric part;
A first downstream electrode provided inside the first dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the first upstream electrode;
A second upstream electrode provided on the discharge space side of the second dielectric part;
A second downstream electrode provided inside the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode;
A third dielectric portion located in the discharge space;
An intermediate electrode embedded in the third dielectric portion and facing the first upstream electrode and the second upstream electrode;
And have a,
In the third dielectric portion, a dielectric constant of a portion on the first dielectric portion side with respect to the intermediate electrode is different from a dielectric constant of a portion on the second dielectric portion side with respect to the intermediate electrode.
Plasma generator. A plasma generator;
A power supply device for applying a voltage to the plasma generator;
Have
The plasma generator is
A first dielectric portion and a second dielectric portion facing each other across the discharge space in a direction intersecting a flow direction in the discharge space;
A first upstream electrode provided on the discharge space side of the first dielectric part;
A first downstream electrode provided inside the first dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the first upstream electrode;
A second upstream electrode provided on the discharge space side of the second dielectric part;
A second downstream electrode provided inside the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode;
An intermediate electrode located in the discharge space and facing the first downstream electrode and the second downstream electrode;
The power supply between the first downstream electrode and the first upstream electrode, and an AC voltage is applied between the second upstream-side electrode and the second downstream electrodes, said first dielectric between the electrodes between the downstream electrode and the intermediate electrode an AC voltage of the dielectric barrier discharge occurs magnitude is applied between the electrodes between, and the said second downstream electrode intermediate electrode An ion wind generator that applies AC voltage with a magnitude that causes body barrier discharge . The power supply device, the first upstream electrode, the second upstream electrode and the intermediate electrode at the same potential, wherein the first downstream electrode and the second downstream electrodes to claim 6, same potential Ion wind generator. The ion wind generator according to claim 6 , wherein the power supply device also applies an AC voltage between the first downstream electrode and the second downstream electrode. A plasma generator;
A power supply device for applying a voltage to the plasma generator;
Have
The plasma generator is
A first dielectric portion and a second dielectric portion facing each other across the discharge space in a direction intersecting a flow direction in the discharge space;
A first upstream electrode provided on the discharge space side of the first dielectric part;
A first downstream electrode provided inside the first dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the first upstream electrode;
A second upstream electrode provided on the discharge space side of the second dielectric part;
A second downstream electrode provided inside the second dielectric part or on the opposite side of the discharge space, and shifted to the downstream side of the discharge space with respect to the second upstream electrode;
A third dielectric portion located in the discharge space;
An intermediate electrode embedded in the third dielectric portion and opposed to the first upstream electrode and the second upstream electrode;
The power supply device applies an AC voltage between the first upstream electrode and the first downstream electrode and between the second upstream electrode and the second downstream electrode, An AC voltage having a magnitude that causes a dielectric barrier discharge between these electrodes is applied between the upstream electrode and the intermediate electrode, and a dielectric is applied between the second upstream electrode and the intermediate electrode between the electrodes. Apply an AC voltage large enough to cause body barrier discharge
Ion wind generator.

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