JP5774960B2 - 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 having a through hole and a pair of electrodes that are embedded in the dielectric and face each other with the through hole interposed therebetween. In the plasma generator, plasma is generated in the through hole 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 through hole is narrowed, the pressure loss of the fluid in the through hole is increased and the flow velocity is decreased. As a result, for example, when the gas is reformed by supplying the gas into the through hole, 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 through hole. Moreover, even if the inner peripheral surface of the through hole 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 through hole becomes wider, the entire through hole is not filled with plasma. As a result, for example, when the gas is reformed by supplying the gas to the through hole, the gas processing efficiency decreases.

  The objective of this invention is providing the plasma generator and plasma generator which can optimize the distribution and flow of the plasma in a through-hole.

  A plasma generator according to an aspect of the present invention includes a dielectric in which a through hole including a discharge space and an introduction space having an inclined surface that expands a diameter opposite to the discharge space as a part of an inner peripheral surface is formed. A first counter electrode facing the discharge space from the inclined surface side in the radial direction of the through hole, the discharge space side being covered by the dielectric, and sandwiching the first counter electrode and the discharge space Between the second counter electrode that is capable of generating plasma in the discharge space when a voltage is applied between the first counter electrode and the first counter electrode. And a first ion wind electrode capable of generating an ion wind flowing from the introduction space side to the discharge space side when a voltage is applied thereto.

  Preferably, the second counter electrode is covered with the dielectric on the discharge space side, and is opposed to the first ion wind electrode with the introduction space interposed therebetween, and the plasma generator is provided with the second counter electrode. There is provided a second ion wind electrode capable of generating an ion wind flowing from the introduction space side to the discharge space side by applying a voltage between the counter electrode and the counter electrode.

  Preferably, the first counter electrode includes a main body portion facing the discharge space, and an extending portion extending along the inclined surface from the main body portion to the introduction space side.

  Preferably, the dielectric is located on the discharge space side with respect to the first counter electrode, and has a higher dielectric constant than a portion positioned on the upstream side, the downstream side, or the outer peripheral side of the first counter electrode. It has a dielectric constant part.

  Preferably, the plasma generator further includes a direct current electrode to which a direct current voltage is applied in a state of not forming a closed loop, which is located downstream of the opposed region of the first opposed electrode and the second opposed electrode.

  A plasma generator according to an aspect of the present invention includes a dielectric having a through hole including a discharge space and an introduction space having an inclined surface that expands a diameter opposite to the discharge space as a part of an inner peripheral surface. A first counter electrode facing the discharge space from the inclined surface side in the radial direction of the through hole, the discharge space side being covered by the dielectric, and sandwiching the first counter electrode and the discharge space A plasma is generated in the discharge space by applying a voltage between the second counter electrode facing each other, the first ion wind electrode positioned on the inclined surface, and the first counter electrode and the second counter electrode. And a power supply device that generates an ion wind that flows from the introduction space side to the discharge space side by applying a voltage between the first counter electrode and the first ion wind electrode.

  According to said structure, the distribution and flow of the plasma in a through-hole can be optimized.

FIG. 1A is a perspective view showing the appearance of the plasma generator according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line Ib-Ib in FIG. Sectional drawing which shows the plasma generator which concerns on the 2nd Embodiment of this invention. Sectional drawing which shows the plasma generator which concerns on the 3rd Embodiment of this invention. 4A and 4B are a cross-sectional view and a perspective view showing a plasma generating apparatus according to a fourth embodiment of the present invention. Sectional drawing which shows the plasma generator which concerns on the 5th 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. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones.

  In the description of each embodiment, components that are the same as or similar to those already described are denoted by the same reference numerals as those already described, and illustrations and descriptions may be omitted.

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

  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 same or similar configurations may be distinguished by attaching different numbers and uppercase alphabets to the same name and the same symbol, such as “first counter electrode 5A” and “second counter electrode 5B”. In addition, there is a case where no distinction is made such as simply “counter electrode 5”.

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

  The plasma generator 1 includes a dielectric 3 and a first counter electrode 5A, a second counter electrode 5B, a first ion wind electrode 7A, and a second ion wind electrode 7B provided on the dielectric 3. Yes. In addition, the plasma generator 1 may have wiring or the like for connecting each electrode to the power supply device 53.

  A through hole 9 is formed in the dielectric 3 so as to penetrate in the x direction. The inside of the through hole 9 is used as a space for generating plasma by discharge. Further, the through hole 9 is also used for generating an ionic wind that flows to one side (the positive side in the x direction) of the through direction.

  The through-hole 9 has, for example, a discharge space 9a mainly used for generating plasma and an introduction space 9b mainly used for optimizing the flow in the discharge space 9a on the upstream side.

  The discharge space 9a is formed in a substantially rectangular parallelepiped shape, for example. Therefore, the opposing surfaces 3a of the dielectric 3 facing each other in the z direction across the discharge space 9a are parallel to each other when viewed in the flow direction (x direction), and when viewed in the flow width direction (y direction). They are parallel to each other. Moreover, the cross-sectional area orthogonal to the penetration direction of the discharge space 9a is constant in the flow direction.

  In the introduction space 9b, for example, a cross-sectional shape (cross-sectional shape shown in FIG. 1B) perpendicular to the width direction (y direction) of the flow is formed in a trapezoidal shape. Therefore, the surface (3e) facing in the z direction across the introduction space 9b of the dielectric 3 is an inclined surface 3e for expanding the diameter of one side of the through hole 9 (negative side in the x direction). The inclined surface 3e is formed, for example, in a flat shape, and the distance between the inclined surfaces 3e facing each other across the introduction space 9b is constant in the flow width direction. Although the inclination angle with respect to the penetration direction (x direction) of the through hole 9 of the inclined surface 3e may be set as appropriate, it is, for example, 30 ° to 60 °.

  The outer shape of the dielectric 3 may be set as appropriate, but is, for example, a rectangular parallelepiped. 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 counter electrode 5 and the ion wind electrode 7 is formed in, for example, a flat plate shape (layer shape) having a constant thickness. The planar shape is, for example, a rectangle. The lengths of these electrodes in the y direction are, for example, the same.

  The two counter electrodes 5 are disposed so as to face each other with the discharge space 9a interposed therebetween. Specifically, for example, the two counter electrodes 5 are embedded in the dielectric 3 so as to be parallel to each other and to be parallel to the counter surface 3a. The two counter electrodes 5 have, for example, the same shape and size as each other, and are disposed at symmetrical positions with respect to the discharge space 9a.

  The ion wind electrode 7 is provided on the inclined surface 3e and exposed to the introduction space 9b. The two ion wind electrodes 7 have, for example, the same shape and size as each other, and are disposed at symmetrical positions with respect to the introduction space 9b (opposing diagonally across the introduction space 9b). .)

  The positional relationship and size relationship between the first counter electrode 5A and the first ion wind electrode 7A and the positional relationship and size relationship between the second counter electrode 5B and the second ion wind electrode 7B are, for example, the same. The positional relationship and the magnitude relationship are as follows, taking the positional relationship and the magnitude relationship of the first counter electrode 5A and the first ion wind electrode 7A as an example.

  In a plan view of the inclined surface 3e provided with the first ion wind electrode 7A, the first counter electrode 5A is located downstream (in the direction indicated by the arrow y1) from the first ion wind electrode 7A (the main line). In the embodiment, the first counter electrode 5A as a whole is provided.

  The first counter electrode 5A is located on the downstream side of the first ion wind electrode 7A in a plan view of the tilted surface 3e provided with the first ion wind electrode 7A and overlaps the tilted surface 3e. It preferably has a portion.

  In addition, in the plan view of the inclined surface 3e provided with the first ion wind electrode 7A, the upstream portion of the first counter electrode 5A overlaps the downstream portion of the first ion wind electrode 7A. Alternatively, they may be adjacent to each other or may be separated (this example is illustrated in the present embodiment).

  Since the first ion wind electrode 7A is provided on the inclined surface 3e, the first ion wind electrode 7A is located on the radially outer side of the through hole 9 with respect to the opposing surface 3a. Further, the first ion wind electrode 7A is located radially outside the portion parallel to the facing surface 3a of the first counter electrode 5A (in this embodiment, the entire first counter electrode 5A).

  In another aspect, the distance between the two ion wind electrodes 7 is longer than the distance between the two counter electrodes 5, and the discharge start electric field strength between the two ion wind electrodes 7 is It is larger than the discharge start electric field strength between the electrodes 5 and the discharge start electric field strength between the counter electrode 5 and the ion wind electrode 7.

  The length of the first counter electrode 5A (x direction) and the length of the first ion wind electrode 7A (direction indicated by the arrow y1) may be set as appropriate. However, from the viewpoint of effectively generating plasma (or ion wind) while reducing the size of the plasma generator 1, the length of the first counter electrode 5A may be longer than the length of the first ion wind electrode 7A. preferable.

  The counter electrode 5 and the ion wind electrode 7 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 is provided between the first counter electrode 5A and the second counter electrode 5B, between the first counter electrode 5A and the first ion wind electrode 7A, and between the second counter electrode 5B and the second ion wind. An AC voltage is applied between the electrode 7B. Preferably, the first counter electrode 5A and the second ion wind electrode 7B have the same potential, and the second counter electrode 5B and the first ion wind electrode 7A 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 dimensions of each part of the dielectric 3, the counter electrode 5, and the ion wind electrode 7, 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 generator 1). May be set as appropriate according to various circumstances such as the technical field to which is applied and the amount of plasma required.

  The method for manufacturing the plasma generator 1 may be, for example, roughly the same manufacturing method as that for the multilayer substrate. 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 as an example, it is as follows.

First, a plurality of ceramic green sheets are prepared. The ceramic green sheet may be laminated in any direction of the x direction, the y direction, and the z direction to constitute the dielectric 3. 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 conductive paste to be the counter electrode 5 is provided on the ceramic green sheet. For example, if the ceramic green sheets are laminated in the z direction, the conductive paste is provided in layers on the main surface (the surface to be overlaid) of the ceramic green sheets. Further, for example, if the ceramic green sheets are stacked in the x direction or the y direction, vias penetrating in the stacking direction are provided in the ceramic green sheets, and the vias are filled with a conductive paste.

  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.

  Next, a plurality of ceramic green sheets are laminated. Next, the through hole 9 is formed by punching. At this time, the inclined surface 3e is formed by making the shape of a part of the punch a shape (trapezoid) whose diameter becomes larger toward the base side, or by making the diameter of the female die larger than the diameter of the punch. Thereafter, a conductive paste to be the ion wind electrode 7 is applied to the inclined surface 3e.

  Thereafter, the laminated ceramic green sheet and conductive paste are fired simultaneously. Thereby, the dielectric 3 in which various electrodes are embedded or formed on the surface and the through hole 9 is formed, that is, the plasma generator 1 is formed.

  In addition, the inclined surface 3e may be formed by performing a pressing process that pushes a part of the through hole 9 apart from the punch for forming the through hole 9. The through-hole 9 before or after the inclined surface 3e is formed may be configured by forming a hole to be the through-hole 9 in the semi-rack green sheet before lamination by punching or laser.

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

The plasma generator 1 is used in a state in which the through-hole 9 is filled with air, a gas to be processed, 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 two counter electrodes 5, an electric field is formed in the discharge space 9a. When the electric field strength exceeds a predetermined discharge start electric field strength, dielectric barrier discharge is started and plasma is generated. Since the two counter electrodes 5 face each other across the discharge space 9a, plasma is generated and filled over the entire zy plane in the discharge space 9a.

  Further, when a voltage is applied to the first counter electrode 5A and the first ion wind electrode 7A, the vicinity of the first counter electrode 5A and the first ion wind electrode 7A in the inner peripheral surface of the through-hole 9 (particularly, the inclination) An electric field is also formed on the downstream portion of the surface 3e and the upstream portion of the facing surface 3a. When the electric field strength exceeds a predetermined discharge start electric field strength, dielectric barrier discharge is started and plasma is generated.

  The electrons or ions in the plasma move due to the electric field formed by the first counter electrode 5A and the first ion wind electrode 7A. Neutral molecules also move with electrons or ions. This induces an ionic wind that flows through the through hole 9 in the penetrating direction. More specifically, since the first ion wind electrode 7A is exposed and the first counter electrode 5A is embedded in the dielectric 3, the first ion wind electrode 7A is directed to the first counter electrode 5A side. Dielectric barrier discharge is generated, and as indicated by an arrow y1, an ion wind flowing from the first ion wind electrode 7A side to the first counter electrode 5A side is generated.

  Further, when a voltage is applied to the second counter electrode 5B and the second ion wind electrode 7B, the second ions are applied in the same manner as when a voltage is applied to the first counter electrode 5A and the first ion wind electrode 7A. An ionic wind flowing from the wind electrode 7B side to the second counter electrode 5B side is generated.

  As described above, in the present embodiment, the plasma generator 1 includes the dielectric 3, the first counter electrode 5A, the second counter electrode 5B, and the first ion wind electrode 7A. A through hole 9 is formed in the dielectric 3, and the through hole 9 has a discharge space 9 a and an introduction space 9 b having an inclined surface 3 e that expands the diameter opposite to the discharge space 9 a as a part of the inner peripheral surface. Including. The first counter electrode 5 </ b> A faces the discharge space 9 a from the radially inclined surface 3 e side (the positive side in the z direction) of the through-hole 9, and the discharge space 9 a side is covered with the dielectric 3. The second counter electrode 5B is opposed to the first counter electrode 5A across the discharge space 9a. The first ion wind electrode 7A is located on the inclined surface 3e on the first counter electrode 5A side. The plasma generator 1 can generate plasma in the discharge space 9a when a voltage is applied between the first counter electrode 5A and the second counter electrode 5B. The first counter electrode 5A and the first ion wind electrode By applying a voltage between 7A, an ion wind flowing from the introduction space 9b to the discharge space 9a can be generated.

  Therefore, even if the through hole 9 (discharge space 9a) is large, the through hole 9 can be filled with plasma. On the other hand, even if the through hole 9 is small, ions are present in the vicinity of the inner peripheral surface (the inclined surface 3e, etc.). Wind can be generated to compensate for flow velocity drop due to pressure loss. That is, it is possible to cause the plasma to flow while suitably filling the through holes of various sizes. As a result, for example, when the plasma treatment is performed on the gas in the through-hole 9, the treatment can be performed efficiently and the degree of freedom in designing the plasma generator 1 is improved. From another point of view, the use range (the range of gas density or flow rate) of the plasma generator 1 can be expanded.

  Furthermore, since the diameter of the through-hole 9 increases toward the upstream side in the introduction space 9b, it becomes easier to take in gas or the like into the discharge space 9a. Further, the ion wind flowing along the inclined surface 3e is obliquely introduced into the discharge space 9a, whereby the diffusion of plasma in the discharge space 9a is promoted, and for example, it is expected that the gas processing efficiency is improved. The

  The second counter electrode 5B is covered with the dielectric 3 on the discharge space 9a side. The plasma generator 1 is opposed to the first ion wind electrode 7A across the introduction space 9b, and a voltage is applied between the second counter electrode 5B and the discharge space 9a from the introduction space 9b side. A second ion wind electrode 7B capable of generating an ion wind flowing to the side is provided. In other words, the plasma generator 1 has the same configuration on the first counter electrode 5A side and the second counter electrode 5B side.

  Therefore, ion wind can be generated on both the first counter electrode 5A side and the second counter electrode 5B side, and the above-described effects are improved. Further, since the two ion wind electrodes 7 are exposed and face each other, there is a risk that arc discharge that is difficult to control compared to dielectric barrier discharge may occur. However, the two ion wind electrodes 7 face each other across the introduction space 9b whose diameter is larger than that of the discharge space 9a, so that the two ion wind electrodes 7 sandwich the space having the same diameter as the discharge space 9a. The occurrence of arc discharge is suppressed as compared with the case of facing each other.

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

  The plasma generator 251 is different from the first embodiment only in the shape of the counter electrode (strictly, the dielectric 3 also). Specifically, it is as follows.

  The counter electrode 205 has a main body portion 205a having the same shape and size as the counter electrode 5 of the first embodiment, and an extending portion 205b extending from the main body portion 205a toward the introduction space 9b. The extending part 205b extends along the inclined surface 3e (for example, in parallel).

  Such a counter electrode 205 forms, for example, an inclined surface 3e by expanding the through-hole 9 in a laminated ceramic green sheet in which conductive paste to be the main body portion 205a and the extending portion 205b are arranged in one flat plate shape. In some cases, the conductive paste is formed by inclining a portion (extending portion 205b) overlapping the inclined surface 3e together with the inclined surface 3e.

  In the plan view of the inclined surface 3e, the ion wind has a shorter distance between the upstream electrode (ion wind electrode 7) and the downstream electrode (counter electrode 5), and in the flow direction of the downstream electrode. The greater the length, the greater the air volume (wind speed). Accordingly, the provision of the extending portion 205b increases the amount of ion wind. As a result, the flow of ion wind from the introduction space 9b to the discharge space 9a also becomes smooth.

  In addition, the extension part 205b may be provided so that it may be located in a shallow position with respect to the inclined surface 3e toward the downstream side. In this case, the extension portion 205b is prevented from locally approaching the ion wind electrode 7, and the entire extension portion 205b is brought close to the ion wind electrode 7 to increase the wind speed over the entire extension portion 205b. Can be obtained.

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

  The plasma generator 351 is different from the first embodiment only in the dielectric material. Specifically, it is as follows.

  In the plasma generator 301 of the plasma generator 351, the dielectric 303 has a high dielectric constant portion 303h having a dielectric constant higher than that of other portions between the counter electrode 5 and the discharge space 9a.

For example, as the material of the dielectric 303, a silica (SiO _2, relative permittivity: 3-4), alumina _(Al 2 _{O 3,} a dielectric constant of 8-11), titanium dioxide (TiO _2, relative permittivity: 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), titanium And barium strontium oxide (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 is a material other than the high dielectric constant portion 303h, and the other one having a higher dielectric constant than the material is the high dielectric constant portion 303. Of it may be the material.

  The high dielectric constant portion 303h may be formed so as to occupy only a part in the z direction or the x direction of the portion between the counter electrode 5 and the discharge space 9a. Similarly to the high dielectric constant portion 303h, a portion having a high dielectric constant (may be regarded as a part of the high dielectric constant portion 303h) is located on the inner peripheral side of the counter electrode 5 and on the upstream side of the counter electrode 5 and It may extend downstream (the high dielectric constant portion 303h may only have a higher dielectric constant than the outer peripheral portion of the counter electrode 5), or from the counter electrode 5 to the outer surface of the dielectric 3 (The high dielectric constant portion 303h may only have a higher dielectric constant than the upstream and downstream portions of the counter electrode 5).

  The high dielectric constant portion 303h preferably extends to the inclined surface 303e, and further, the high dielectric constant portion 303h extended to the inclined surface 303e extends to the downstream edge of the ion wind electrode 7. Is preferred.

  For example, among the ceramic green sheets stacked in the z direction, the dielectric 303 may be a ceramic green sheet positioned between the counter electrode 5 and the discharge space 9a having a higher dielectric constant than other ceramic green sheets ( In this case, the dielectric 303 has a relatively higher dielectric constant on the entire discharge space 9a side than the counter electrode 5). Among the ceramic green sheets laminated in the x direction, the ceramic green sheet provided with the counter electrode 5 Or a dielectric constant higher than that of other ceramic green sheets (in this case, the dielectric 303 has a relatively high dielectric constant over the entire range of the counter electrode 5 in the x direction). The Further, after forming a through hole having a diameter larger than that of the through hole 9 in the laminated ceramic green sheet, an insulating material having a relatively high dielectric constant is applied to the inner surface of the ceramic green sheet so that the high dielectric constant portion 303h and the through hole 9 are formed. It may be formed.

  According to this embodiment, since the dielectric constant between the counter electrodes 5 is increased, the amount of plasma generated can be increased. On the other hand, in portions other than the high dielectric constant portion 303h, it is possible to select a material that is advantageous in terms of material cost or material strength. Further, an increase in the amount of plasma generated between the ion wind electrode 7 and the counter electrode 5 and an increase in the ion wind are also expected.

<Fourth Embodiment>
FIG. 4A is a cross-sectional view corresponding to FIG. 1B showing the configuration of the plasma generator 451 according to the fourth embodiment, and FIG. 4B is the plasma generation of the plasma generator 451. It is the perspective view which looked at the body 401 from the downstream.

  The plasma generator 451 is different from the first embodiment only in that it includes a first DC electrode 411A to a third DC electrode 411C and a DC power supply device 457 that applies a DC voltage to these DC electrodes 411. Specifically, it is as follows.

  All of the three DC electrodes 411 are located on the downstream side (positive side in the x direction) with respect to the opposing region of the two opposing electrodes 5. More specifically, the first DC electrode 411A and the second DC electrode 411B are formed in a flat plate shape, for example, and are provided downstream of the counter electrode 5 on the counter surface 3a. The first DC electrode 411A and the second DC electrode 411B are formed in the same shape and size, for example, and face each other. The third DC electrode 411C is formed in a net shape, and is fixed to the dielectric 3 directly or indirectly so as to close the downstream side of the through hole 9.

  The DC power supply device 457 applies a DC voltage to the DC electrode 411 without forming a closed loop. That is, only the positive terminal or the negative terminal of the DC power supply device 457 is connected to the DC electrode 411, and a closed loop through which a current from the DC power supply device 457 flows is not configured.

  FIG. 4A illustrates the case where the same potential is applied to the first DC electrode 411A to the third DC electrode 411C, but the potentials applied to these are different in positive and negative. And / or the absolute values of the potentials may be different from each other. However, when the potentials are different between the DC electrodes 411, it is preferable to suppress the voltage so that no discharge occurs between the DC electrodes.

  When a DC voltage is applied to the DC electrode 411 by the DC power supply device 457, an electric field is formed around the DC electrode 411. In other words, an electric field is formed in the downstream area of the ion wind or downstream of the counter area of the counter electrode 5.

  Therefore, the ion wind can be accelerated by attracting electrons or ions contained in the plasma (ion wind) to the DC electrode 411 side. For example, if a positive potential is applied to the DC electrode 411, negative charges are attracted to the DC electrode 411, the ion wind can be accelerated, and if a negative potential is applied to the DC electrode 411. , Positive charges are attracted to the DC electrode 411, and the ion wind can be accelerated. Moreover, since the DC electrode 411 does not constitute a closed loop, power consumption is extremely low.

  Of the three DC electrodes 411, only one or only two of them may be provided. Further, in addition to or instead of these DC electrodes 411, another DC electrode such as a DC electrode positioned on a side surface orthogonal to the y direction of the through hole 9 may be provided.

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

  As illustrated in the plasma generator 501 of the plasma generator 551, it is not necessary to provide two ion wind electrodes 7 corresponding to the two counter electrodes 5, but one counter electrode 5 (first counter electrode 5 </ b> A). Only one may be provided correspondingly only to.

  In this case, the two counter electrodes 5 do not need to be separated from the discharge space 509a by the dielectric 503, and the second counter electrode 5B may be exposed to the discharge space 509a.

  Further, the counter electrode 5 (only the first counter electrode 5A in the present embodiment) whose discharge space 509a side is covered with the dielectric 503 does not need to be embedded in the dielectric 503, and is provided on the outer surface of the dielectric 503. It may be.

  The inclined surface 503e does not need to be provided on both the first counter electrode 5A side and the second counter electrode 5B side, and may be provided only on one side (first counter electrode 5A side). In FIG. 5, the second ion wind electrode 7B is not provided, but when the discharge space 509a side of the second counter electrode 5B is covered with the dielectric 503, the second counter electrode 5B is inclined to face the inclined surface 503e. The second ion wind electrode 7B may be provided on the inner peripheral surface that is not.

  The introduction space 509b does not need to be an inlet of the through hole 509, and may be a space downstream of the inlet 509c having a constant cross-sectional area as illustrated in FIG.

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

  The first to fifth embodiments may be appropriately combined. For example, a feature of providing an extended portion on the counter electrode (second embodiment), a feature of providing a high dielectric constant portion on the dielectric (third embodiment), and a feature of providing a DC electrode (fourth embodiment) ) May be selected by combining two or more of these.

  The various electrodes are not limited to the shapes exemplified in the embodiment such as a rectangular flat plate shape, and the arrangement positions thereof may be appropriately set.

  For example, the downstream side electrode (first counter electrode or the like) that generates ion wind is formed to be longer in the ion wind flow direction (x direction) toward the side (positive side or negative side in the y direction). May be. 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 orthogonal to the y direction can be compensated.

  Further, for example, the DC electrode may be one whose position in the flow direction changes according to the position in the y direction. In this case, the acceleration effect can be changed according to the position in the direction orthogonal to the flow, and for example, the pressure loss on the side surface orthogonal to the y direction of the through hole can be compensated. Further, for example, the DC electrode may have an axial shape extending in a direction orthogonal to the flow. In this case, size reduction in the flow direction can be achieved.

  The first ion wind electrode need not have the same potential as the second counter electrode. Similarly, the second ion wind electrode need not have the same potential as the first counter electrode. For example, the same potential (or a relatively small potential difference) is applied to the first ion wind electrode and the second ion wind electrode, and the voltage varies between a high potential and a low potential with respect to the predetermined potential. An alternating voltage may be applied to the first counter electrode and the second counter electrode. In this case, the discharge start electric field strength between the two ion wind electrodes may not be larger than the discharge start electric field strength between the two counter electrodes. In addition, for example, in the case of voltage application as described above, or in the case where the second ion wind electrode is not provided, the first ion wind electrode and the second counter electrode covered with the dielectric are interposed between the first ion wind electrode and the second counter electrode covered with the dielectric. Also, a voltage may be applied so that dielectric barrier discharge occurs. In this case, the downstream end of the first ion wind electrode does not have to be positioned radially outside the first counter electrode. Further, for example, a three-phase AC voltage may be applied to the first counter electrode, the second counter electrode, and the first ion wind electrode. However, the configuration of the power supply device is simplified by setting the first ion wind electrode and the second counter electrode to the same potential.

  The ion wind electrode may not be exposed to the discharge space. For example, the ion wind electrode may be coated with a dielectric thin film. Further, the electrode exposed to the discharge space or coated (the ion wind electrode or the second counter electrode 5B of the fifth embodiment) is not limited to the one superimposed on the surface of the dielectric, and is formed on the dielectric. It may be fitted in the recess and have a surface flush with the surface of the dielectric.

  The shape of the through hole is not limited to that exemplified in the embodiment. For example, the side surface (surface orthogonal to the y direction) may be formed in a concave shape. Further, for example, the inclined surface may be curved so as to swell or dent when viewed from the side (viewed in the y direction). However, the opposing surface (3a) and the inclined surface (3e) of the through hole are parallel to each other when viewed in the flow direction (x direction) so that the electric field and dielectric breakdown strength in the width direction (y direction) are uniform. Preferably there is. Moreover, it is preferable that an opposing surface is a mutually parallel plane.

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

  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 generating body, 3 ... Dielectric, 5A ... 1st counter electrode, 5B ... 2nd counter electrode, 7A ... 1st ion wind electrode, 9 ... Through-hole, 9a ... Discharge space, 9b ... Introduction space.

Claims (6)

A dielectric formed with a through-hole including a discharge space and an introduction space having an inclined surface that expands a diameter opposite to the discharge space as a part of the inner peripheral surface;
A first counter electrode facing the discharge space from the inclined surface side in the radial direction of the through-hole, the discharge space side being covered with the dielectric;
A second counter electrode that is opposed to the first counter electrode with the discharge space interposed therebetween, and is capable of generating plasma in the discharge space by applying a voltage between the first counter electrode;
A first ion wind electrode that is located on the inclined surface and can generate an ion wind flowing from the introduction space side to the discharge space side by applying a voltage between the first counter electrode and the first counter electrode;
I have a,
A plasma generator in which the first counter electrode is used for both plasma generation and ion wind generation. The second counter electrode is covered with the dielectric on the discharge space side,
The first ion wind electrode is opposed across the introduction space, and an ion wind flowing from the introduction space side to the discharge space side can be generated by applying a voltage between the second counter electrode. The plasma generator according to claim 1, wherein a second ion wind electrode is provided. The first counter electrode is
A main body facing the discharge space;
The plasma generator according to claim 1, further comprising: an extending portion extending along the inclined surface from the main body portion toward the introduction space. The dielectric has a high dielectric constant portion located on the discharge space side with respect to the first counter electrode and having a dielectric constant larger than a portion located on the upstream side, the downstream side, or the outer peripheral side of the first counter electrode. The plasma generator according to any one of claims 1 to 3. 5. The apparatus according to claim 1, further comprising a direct current electrode that is positioned downstream of the opposed region of the first opposed electrode and the second opposed electrode and to which a direct current voltage is applied without forming a closed loop. The plasma generator as described. A dielectric formed with a through-hole including a discharge space and an introduction space having an inclined surface that expands a diameter opposite to the discharge space as a part of the inner peripheral surface;
A first counter electrode facing the discharge space from the inclined surface side in the radial direction of the through-hole, the discharge space side being covered with the dielectric;
A second counter electrode facing the first counter electrode across the discharge space;
A first ion wind electrode located on the inclined surface;
A voltage is applied between the first counter electrode and the second counter electrode to generate plasma in the discharge space, and a voltage is applied between the first counter electrode and the first ion wind electrode. And a power supply device for generating ion wind flowing from the introduction space side to the discharge space side,
I have a,
A plasma generator in which the first counter electrode is used for both plasma generation and ion wind generation.

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