Antenna and plasma processing apparatus

Abstract

To sufficiently uniformly supply a current to each of second electrode of a capacitive element when increasing the electrostatic capacity of the capacitive element provided in an antenna.SOLUTION: An antenna (3) includes an antenna element (31) and a capacitive element (32), the capacitive element (32) includes a first electrode (32A) and a second electrode (32B), and inside a first columnar portion (321A) of the first electrode (32A), a plurality of through holes (H1) that is formed side by side along the side surface (ES1) of the first columnar portion (321A), and into which a plurality of rod-shaped electrodes (32C) of the second electrode (32B) is respectively inserted is formed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an antenna and a plasma processing apparatus.

Background Art

[0002] Patent Document 1 discloses an antenna for generating plasma, which includes at least two conductor elements and a capacitive element electrically connected in series with adjacent conductor elements. The capacitive element has a first electrode electrically connected to one of the adjacent conductor elements and a second electrode electrically connected to the other of the adjacent conductor elements.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the antenna disclosed in Patent Document 1, the extending portions of the first electrode and the second electrode have a cylindrical shape and are arranged coaxially with each other. Therefore, due to the skin effect, the current flows less easily through the inner electrode than the outer electrode for the first electrode and the second electrode, and there is a possibility that no current flows through the inner electrode.

[0005] One aspect of the present disclosure aims to allow current to flow sufficiently uniformly through each second electrode of the capacitive element when increasing the capacitance of the capacitive element provided in the antenna.

Means for Solving the Problems

[0006] In order to solve the above problems, an antenna according to one aspect of the present disclosure is an antenna that extends along an axis and emits electromagnetic waves for generating plasma by passing a high-frequency current therethrough, and includes at least two antenna elements sequentially arranged along the axis, and at least one capacitance element arranged between two adjacent antenna elements. The capacitance element has a first electrode electrically connected to one of the adjacent antenna elements and a second electrode electrically connected to the other of the adjacent antenna elements. The first electrode has a first cylindrical portion extending in the axial direction, and the second electrode has a plurality of rod-shaped electrodes extending in the axial direction. Inside the first cylindrical portion, there is a through hole extending in the axial direction, which is formed side by side along the side surface of the first cylindrical portion, and a plurality of through holes into which each of the plurality of rod-shaped electrodes is inserted are formed.

Effect of the Invention

[0007] According to one aspect of the present disclosure, when increasing the capacitance of the capacitance element included in the antenna, current can flow sufficiently uniformly through each second electrode of the capacitance element.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009]

Embodiment 1

[0010] As shown in FIG. 1, the plasma processing apparatus 1 performs plasma processing on a substrate W1 using an inductively coupled plasma P1. The substrate W1 is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, or a flexible substrate for a flexible display. Further, the processing performed on the substrate W1 is, for example, film formation by plasma CVD method or sputtering method, etching by plasma, ashing, or removal of a coating film.

[0011] The plasma processing apparatus 1 includes a vacuum vessel 2, an antenna 3, a high-frequency power source 4, a vacuum exhaust device 5, a holding unit 6, an insulating cover 7, and an insulating member 8. The vacuum vessel 2 is, for example, a metal container, and the inside of the vacuum vessel 2 is evacuated by the vacuum exhaust device 5. The vacuum vessel 2 is electrically grounded. A gas inlet 21 is formed in the vacuum vessel 2, and a gas G1 is introduced into the inside of the vacuum vessel 2 through the gas inlet 21.

[0012] The gas G1 may be selected according to the processing content to be performed on the substrate W1. For example, when forming a film on the substrate W1 by plasma CVD method, the gas G1 is a source gas or a gas diluted with a dilution gas such as H2. More specifically, when the source gas is SiH4, an Si film can be formed on the substrate W1, when it is SiH4 + NH3, an SiN film can be formed, when it is SiH4 + O2, an SiO2 film can be formed, and when it is SiF4 + N2, an SiN:F film (fluorinated silicon nitride film) can be formed on the substrate W1, respectively.

[0013] Antenna 3 emits electromagnetic waves for generating plasma P1 by passing a high-frequency current IR therethrough, and is disposed inside the vacuum chamber 2. Antenna 3 is disposed inside the vacuum chamber 2 on the +Z-axis side with respect to the substrate W1 along the surface of the substrate W1. The number of antennas 3 disposed inside the vacuum chamber 2 may be one or plural.

[0014] The high-frequency power supply 4 applies a high frequency for generating plasma P1 inside the vacuum chamber 2 to the antenna 3. When the high-frequency power supply 4 applies a high frequency to the antenna 3, a high-frequency current IR flows through the antenna 3, an induced electric field is generated inside the vacuum chamber 2, and plasma P1 is generated. The holding unit 6 is provided inside the vacuum chamber 2 and holds the substrate W1.

[0015] Both ends of the antenna 3 penetrate through the opposing side walls of the vacuum chamber 2 respectively. Insulating members 8 are respectively provided at the portions of the vacuum chamber 2 through which both ends of the antenna 3 penetrate. Both ends of the antenna 3 penetrate through the respective insulating members 8. A packing 9 is provided between the antenna 3 and the insulating member 8. A packing 10 is also provided between the vacuum chamber 2 and the insulating member 8.

[0016] The material of the insulating member 8 is, for example, ceramics such as alumina, quartz, or engineering plastics such as polyphenylene sulfide (PPS) or polyether ether ketone (PEEK). The portion of the antenna 3 located inside the vacuum chamber 2 is covered by a tubular insulating cover 7. Both ends of the insulating cover 7 are supported by the insulating members 8. Most of the insulating cover 7 does not contact the antenna 3.

[0017] Note that it is not necessary to seal between both ends of the insulating cover 7 and the insulating member 8. The space inside the insulating cover 7 is small, and even if gas G1 enters the space inside the insulating cover 7, the movement distance of charged particles is short. Therefore, plasma P1 usually does not generate in the space inside the insulating cover 7. Also, the material of the insulating cover 7 is an inorganic high-resistance material such as quartz, alumina, silicon nitride, or silicon carbide, for example.

[0018] By providing the insulating cover 7, the amount of charged particles in the plasma P1 incident on the antenna 3 can be suppressed. For this reason, it is possible to suppress an increase in the plasma potential of the antenna 3 due to the incidence of charged particles on the antenna 3, and it is possible to suppress the antenna 3 from being sputtered by charged particles and causing metal contamination to the substrate W1.

[0019] A high-frequency power supply 4 is connected to a power feeding end portion 3a which is one end portion of the antenna 3 via a matching circuit 41, and a termination end portion 3b which is the other end portion of the antenna 3 is directly grounded. Note that the termination end portion 3b may be grounded via a capacitor, a coil, or the like. The high-frequency power supply 4 can pass a high-frequency current IR through the antenna 3 via the matching circuit 41. The frequency of the high frequency is, for example, a general 13.56 MHz, but is not limited thereto.

[0020] The cooling liquid CL flows through the antenna 3 by a circulation flow path 11 provided outside the vacuum container 2. A temperature control mechanism 12 and a circulation mechanism 13 are provided in the circulation flow path 11. The temperature control mechanism 12 is a heat exchanger or the like for adjusting the cooling liquid CL to a constant temperature. The circulation mechanism 13 is a pump or the like for circulating the cooling liquid CL in the circulation flow path 11. From the viewpoint of electrical insulation, high-resistance water is preferable as the cooling liquid CL, and for example, pure water or water close thereto is preferable. Also, as the cooling liquid CL, a liquid refrigerant other than water such as a fluorine-based inert liquid may be used.

[0021] <Internal structure of antenna 3> FIG. 2 is a cross-sectional view showing the internal structure of the antenna 3 provided in the plasma processing apparatus 1 shown in FIG. 1. As shown in FIG. 2, the antenna 3 includes at least two antenna elements 31, at least one capacitive element 32, and an insulating element 33. The antenna 3 extends along the axis AX and has a hollow structure in which a flow path for the coolant CL to flow is formed inside. The axis AX is an axis along the X-axis direction.

[0022] At least two antenna elements 31 are sequentially arranged along the axis AX and are arranged adjacent to each other in the X-axis direction. The antenna element 31 is a metal pipe made of metal having a tubular shape. The antenna element 31 has a tubular shape in which a linear flow path for the coolant CL to flow is formed inside. The material of the antenna element 31 is, for example, copper, aluminum, an alloy thereof, or stainless steel. FIG. 2 shows two adjacent antenna elements 31. One of the two adjacent antenna elements 31 is defined as antenna element 31A, and the other of the two adjacent antenna elements 31 is defined as antenna element 31B.

[0023] The capacitive element 32 is arranged between two adjacent antenna elements 31. The capacitive element 32 has a first electrode 32A and a second electrode 32B. The first electrode 32A is electrically connected to the antenna element 31A, and the second electrode 32B is electrically connected to the antenna element 31B. The capacitive element 32 is electrically connected in series with the antenna elements 31A and 31B.

[0024] The first electrode 32A is inserted inside the insulating element 33. The first electrode 32A has a first cylindrical portion 321A, a second cylindrical portion 321B, and a first connection portion 321C that extend in the X-axis direction. A plurality of through holes H1 that extend in the X-axis direction are formed inside the first cylindrical portion 321A. The second cylindrical portion 321B is connected to the first cylindrical portion 321A such that the side surfaces are continuous.

[0025] Inside the second cylindrical portion 321B, an internal space SP1 communicating with each through-hole H1 is formed. The first connection portion 321C connects the antenna element 31A and the insulating element 33. Further, the first connection portion 321C is connected to the second cylindrical portion 321B such that the side surfaces are continuous.

[0026] The first cylindrical portion 321A, the second cylindrical portion 321B, and the first connection portion 321C are formed of an integral member. The integral member is a member formed by integral molding or an assembled member in which a plurality of members are joined by welding or the like and assembled. As shown in FIG. 2, inside the first electrode 32A, the inner diameter of the second cylindrical portion 321B is larger than the inner diameter of the first connection portion 321C, but the inner diameter of the second cylindrical portion 321B may be the same as the inner diameter of the first connection portion 321C.

[0027] The second electrode 32B has a plurality of rod-shaped electrodes 32C and a second connection portion 32D. The second connection portion 32D is composed of a protruding portion 326 and a connection portion 327. The second connection portion 32D is a portion of the second electrode 32B that connects to the antenna element 31B. The protruding portion 326 protrudes from the connection portion 327 in the negative X-axis direction.

[0028] A plurality of through-holes H2 extending in the direction from the outside to the inside of the antenna 3 are formed in a portion of the protruding portion 326 adjacent to the connection portion 327. The plurality of through-holes H2 are formed in the protruding portion 326 so as to be arranged along the circumferential direction of the antenna 3. By forming the through-holes H2 in the protruding portion 326, the coolant CL between the insulating element 33 and the protruding portion 326 can flow in the positive X-axis direction.

[0029] The connection portion 327 connects the antenna element 31B and the insulating element 33. Each of the plurality of rod-shaped electrodes 32C is inserted into one of the plurality of through-holes H1. The materials of the first electrode 32A and the second electrode 32B are, for example, aluminum, copper, or alloys thereof. Note that the first electrode 32A and the second electrode 32B may be subjected to surface treatment such as anodizing according to the respective materials of the electrodes in order to suppress electrochemical degradation of each electrode by the coolant CL.

[0030] The rod-shaped electrode 32C has an extension portion 321, a flange portion 322, and a protrusion portion 323. The extension portion 321 extends in the X-axis direction. The flange portion 322 is provided at the rear end of the extension portion 321 so as to be substantially orthogonal to the extension direction of the extension portion 321, that is, the X-axis direction. The protrusion portion 323 is connected to the flange portion 322. The flange portion 322 and the protrusion portion 323 constitute the rear end of the rod-shaped electrode 32C.

[0031] The rod-shaped electrode 32C is connected to the second connection portion 32D by inserting the protrusion portion 323 into the protruding portion 326 of the second connection portion 32D. Note that the protrusion portion 323 may be fixed to the protruding portion 326 by a fixing member such as a pin or a screw. Further, the rod-shaped electrode 32C may be fixed to the protruding portion 326 by screwing the protrusion portion 323 into a screw hole formed in the protruding portion 326.

[0032] By inserting the protrusion portion 323 into the second connection portion 32D, the length L1 of the portion of the rod-shaped electrode 32C surrounded by the through hole H1 can be accurately determined. Further, since the flange portion 322 is substantially orthogonal to the extension direction of the rod-shaped electrode 32C, the rod-shaped electrode 32C can be easily connected to the second connection portion 32D so that the extension direction of the rod-shaped electrode 32C coincides with the extension direction of the through hole H1.

[0033] A recess 324 is formed in the side surface ES2 of the first connection portion 321C, and a packing 325 such as an O-ring is fitted into the recess 324. Thereby, it is possible to prevent the coolant CL from flowing between the insulating element 33 and the first electrode 32A. Further, a recess 328 is formed in the side surface ES3 of the connection portion 327, and a packing 329 such as an O-ring is fitted into the recess 328. Thereby, it is possible to prevent the coolant CL from flowing between the insulating element 33 and the connection portion 327.

[0034] The insulating element 33 is provided between the antenna element 31A and the antenna element 31B, and is a tubular insulating pipe connected to each of the antenna element 31A and the antenna element 31B. Thereby, each of the antenna elements 31 adjacent to each other can be insulated by the insulating element 33.

[0035] Inside the insulating element 33, a linear flow path through which the coolant CL flows is formed, and the first electrode 32A and the second electrode 32B are inserted. The material of the insulating element 33 is, for example, ceramics such as alumina, fluororesin, polyethylene (PE), or engineering plastics such as polyphenylene sulfide (PPS) or polyether ether ketone (PEEK).

[0036] Further, the insulating element 33 is provided with a fixing member 34 that penetrates the insulating element 33 and is inserted into the first connection portion 321C. Thereby, the first electrode 32A is fixed to the insulating element 33 by the fixing member 34. Furthermore, the insulating element 33 is provided with a fixing member 35 that penetrates the insulating element 33 and is inserted into the connection portion 327. Thereby, the second electrode 32B is fixed to the insulating element 33 by the fixing member 35. The fixing members 34 and 35 are, for example, pins or screws.

[0037] [[ID=AB]]When the first electrode 32A and the second electrode 32B are fixed to the insulating element 33, the positions of the central axis of the first electrode 32A and the central axis of the second electrode 32B can be accurately determined. Thereby, the relative position between the through hole H1 formed in the first electrode 32A and the central axis of the rod-shaped electrode 32C can be accurately determined, and it is easily possible to uniformly flow the coolant CL around the rod-shaped electrode 32C.

[0038] FIG. 3 is a cross-sectional view taken along line A1-A1 of the antenna 3 shown in FIG. 2. As shown in FIG. 3, inside the first cylindrical portion 321A, a plurality of through holes H1 are formed annularly along the side surface ES1 of the first cylindrical portion 321A. A coolant CL, which is a dielectric, flows in a space SP2 between the inner surface I1 of the first cylindrical portion 321A that defines the through hole H1 and the extending portion 321. Thereby, a capacitor can be constituted by the first cylindrical portion 321A, the extending portion 321, and the coolant CL. The space SP2 is a space included in the space surrounded by the inner surface I1.

[0039] Since each of the plurality of rod-shaped electrodes 32C is inserted into a plurality of through holes H1 formed side by side along the side surface ES1 of the first cylindrical portion 321A, each rod-shaped electrode 32C is arranged along the side surface ES1 of the first cylindrical portion 321A. Therefore, the difference in the ease of current flow in each rod-shaped electrode 32C due to the skin effect with respect to the first electrode 32A can be made sufficiently small. Thus, when increasing the capacitance of the capacitive element 32, current can be made to flow through each rod-shaped electrode 32C sufficiently uniformly.

[0040] Further, since the plurality of through holes H1 are formed side by side along the side surface ES1 of the first cylindrical portion 321A, the size of the capacitive element 32 can be made smaller than the case where the antenna is constituted by a multiple structure in which the electrodes of the capacitive element overlap in the circumferential direction of the antenna. Therefore, the antenna 3 can be made thinner, and miniaturization of the antenna 3 can be realized.

[0041] In FIG. 3, the plurality of through holes H1 are formed inside the first cylindrical portion 321A along one circle C1, but they may be formed inside the first cylindrical portion 321A along a plurality of circles having different radii. That is, the plurality of through holes H1 may be formed inside the first cylindrical portion 321A alternately.

[0042] By forming a plurality of spaces SP2 between the inner surface I1 of the first cylindrical portion 321A and the extending portion 321, the area of the portion of the first cylindrical portion 321A facing the extending portion 321 can be increased as compared with the case where one space SP2 is formed. For example, in FIG. 3, six spaces SP2 are formed, and the capacitance when six spaces SP2 are formed is six times the capacitance when one space SP2 is formed. Therefore, the capacitance of the capacitive element 32 can be increased, and the amplitude of increase and decrease of the voltage of the antenna 3 can be reduced.

[0043] 〔Embodiment 2〕 Embodiment 2 of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in Embodiment 1 are denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 4 is a cross-sectional view showing the internal structure of an antenna 3A provided in the plasma processing apparatus according to Embodiment 2 of the present disclosure. The plasma processing apparatus according to Embodiment 2 is different from the plasma processing apparatus according to Embodiment 1 in that the antenna 3 is changed to an antenna 3A. Here, the differences between the antenna 3A and the antenna 3 will be described.

[0044] As shown in FIG. 4, an internal space SP3 communicating with a plurality of through holes H1 is formed inside the second cylindrical portion 521B of the antenna 3A. The length of the extending portion 521 of the rod-shaped electrode 52C of the antenna 3A is longer than the length of the extending portion 321, and the tip E1 of each of the extending portions 521 of the plurality of rod-shaped electrodes 52C is disposed in the internal space SP3.

[0045] That is, the tip E1 of the extending portion 521 is disposed outside the through hole H1. Since the tip E1 of the rod-shaped electrode 52C is disposed in the internal space SP3 communicating with each of the plurality of through holes H1, it is possible to reduce the concentration of the electric field at the tip E1 of the rod-shaped electrode 52C.

[0046] Further, the inner surface IS of the second cylindrical portion 521B surrounding the internal space SP3 is formed at a position farther from the central axis AX1 of the first electrode 52A than the plurality of through holes H1. As a result, the distance between the tip E1 of the rod-shaped electrode 52C and the inner surface IS of the second cylindrical portion 521B surrounding the internal space SP3 where the tip E1 of the rod-shaped electrode 52C is disposed is increased, so that the concentration of the electric field at the tip E1 of the rod-shaped electrode 52C can be further reduced.

[0047] Furthermore, a notch CT is formed at the boundary portion between the inner surface IS surrounding the internal space SP3 and the through hole H1. As a result, the distance between the tip E1 of the extension portion 521 and the first electrode 52A is increased, so that the concentration of the electric field at the tip E1 can be further reduced. Also, a notch CT2 is formed on the side of the first electrode 52A facing the protruding portion 526.

[0048] 〔Embodiment 3〕 Embodiment 3 of the present disclosure will be described below. For the sake of convenience of explanation, members having the same functions as those described in Embodiments 1 and 2 are denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 5 is a cross-sectional view showing the internal structure of the antenna 3B provided in the plasma processing apparatus according to Embodiment 3 of the present disclosure. The plasma processing apparatus according to Embodiment 3 is different from the plasma processing apparatus according to Embodiment 2 in that the antenna 3A is changed to the antenna 3B. Here, the content in which the antenna 3B is different from the antenna 3A will be described.

[0049] As shown in FIG. 5, the first electrode 62A of the antenna 3B has a first cylindrical portion 621A, a second cylindrical portion 621B, and a first connection portion 621C. The first cylindrical portion 621A is provided inside the insulating element 33. A plurality of through holes H1 are formed inside the first cylindrical portion 621A. The first cylindrical portion 621A and the second cylindrical portion 621B are formed of an integral member. The second cylindrical portion 621B is connected to the first connection portion 621C and is provided inside the insulating element 33. The first connection portion 621C is a portion of the first electrode 62A that connects to the antenna element 31B. The first connection portion 621C connects the antenna element 31A and the insulating element 33.

[0050] The integral member constituting the first cylindrical portion 621A and the second cylindrical portion 621B is fixed to the insulating element 33 by an adhesive or the like. In addition, the convex portion formed on one of the integral member and the insulating element 33 may be fitted into the concave portion formed on the other of the integral member and the insulating element 33, whereby the integral member may be fixed to the insulating element 33.

[0051] Further, the first connection portion 621C is provided so as to be separable from the integral member constituting the first cylindrical portion 621A and the second cylindrical portion 621B. Since the first connection portion 621C is provided so as to be separable from the integral member, when assembling the antenna 3B, the first connection portion 621C can be separated from the integral member to check the positional relationship between the through hole H1 and the rod-shaped electrode 52C. Also, even when maintenance is performed on the antenna 3B, the first connection portion 621C can be separated from the integral member to check the positional relationship between the through hole H1 and the rod-shaped electrode 52C.

[0052] 〔Embodiment 4〕 Embodiment 4 of the present disclosure will be described below. For the sake of convenience of explanation, members having the same functions as the members described in Embodiments 1 to 3 are denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 6 is a cross-sectional view showing a cross-sectional configuration of a plasma processing apparatus 1A according to Embodiment 4 of the present disclosure. Here, the plasma processing apparatus 1A according to Embodiment 4 will be described with respect to the content different from that of the plasma processing apparatus 1.

[0053] As shown in FIG. 6, the plasma processing apparatus 1A includes a plurality of antennas 3 and a connection conductor 71. Both ends of each antenna 3 penetrate through the mutually facing side walls of the vacuum chamber 2. Each antenna 3 may include a plurality of capacitive elements 32 and a plurality of insulating elements 33. The antenna element 31, the capacitive element 32, and the insulating element 33 are alternately connected.

[0054] One end of one of the antennas 3 adjacent to each other and the end of the other antenna 3 may be electrically connected by a connection conductor 71. Here, the ends of the two antennas 3 connected by the connection conductor 71 are the ends located on the same side wall side. Thereby, the plurality of antennas 3 are configured such that high-frequency currents IR flowing in opposite directions flow through the antennas 3 adjacent to each other. By forming the plurality of antennas 3 into a single antenna structure by the connection conductor 71, the plasma processing apparatus 1A can perform plasma processing on a large substrate W1.

[0055] A flow path through which a coolant CL flows is formed inside the connection conductor 71. Specifically, one end of the connection conductor 71 communicates with the flow path of one of the antennas 3, and the other end of the connection conductor 71 communicates with the flow path of the other antenna 3. Thereby, the coolant CL that has flowed through one of the antennas 3 adjacent to each other flows into the flow path of the other antenna 3 through the flow path of the connection conductor 71. Also, both the antenna 3 and the connection conductor 71 can be cooled by the common coolant CL. Furthermore, since a plurality of antennas 3 can be cooled by a single flow path, the configuration of the circulation flow path 11 can be simplified.

[0056] The connection conductor 71 includes one conductor part 71A, the other conductor part 71B, and a capacitive element 71C. One conductor part 71A is connected to one of the antennas 3 adjacent to each other. The other conductor part 71B is connected to the other of the antennas 3 adjacent to each other. The capacitive element 71C is electrically connected in series to the conductor part 71A and the conductor part 71B.

[0057] Note that the configuration of the conductor parts 71A and 71B may be the same as, for example, the configuration of the antenna element 31, and the configuration of the capacitive element 71C may be the same as, for example, the configuration of the capacitive element 32. Thus, by having the capacitive element 71C in the connection conductor 71, the impedance of the connection conductor 71 can be made equivalent to zero, and an increase in impedance due to the connection conductor 71 can be reduced.

[0058] 〔Summary〕 An antenna according to one aspect of the present disclosure is an antenna that extends along an axis and emits electromagnetic waves for generating plasma by energizing a high-frequency current, and includes at least two antenna elements sequentially arranged along the axis, and at least one capacitor element arranged between two adjacent antenna elements. The capacitor element has a first electrode electrically connected to one of the adjacent antenna elements and a second electrode electrically connected to the other of the adjacent antenna elements. The first electrode has a first cylindrical portion extending in the axial direction, and the second electrode has a plurality of rod-shaped electrodes extending in the axial direction. Inside the first cylindrical portion, there is a through hole extending in the axial direction, which is formed side by side along the side surface of the first cylindrical portion, and a plurality of through holes into which each of the plurality of rod-shaped electrodes is inserted are formed.

[0059] According to the above configuration, since each of the plurality of rod-shaped electrodes is inserted into a plurality of through holes formed side by side along the side surface of the first cylindrical portion, each rod-shaped electrode is arranged along the side surface of the first cylindrical portion. Therefore, the difference in the ease of current flow in each rod-shaped electrode due to the skin effect with respect to the first electrode can be made sufficiently small. Thus, when increasing the capacitance of the capacitor element, current can flow through each rod-shaped electrode sufficiently uniformly.

[0060] In the antenna according to the above aspect, a coolant may flow in a space between an inner surface of the first cylindrical portion defining the through hole and the rod-shaped electrode. According to the above configuration, a capacitor can be constituted by the first cylindrical portion, the rod-shaped electrode, and the coolant.

[0061] In the antenna according to the above aspect, the first electrode has a second cylindrical portion connected to the first cylindrical portion such that the side surfaces are continuous. An internal space communicating with each of the through holes is formed inside the second cylindrical portion, and the tip of each of the rod-shaped electrodes may be disposed in the internal space. According to the above configuration, since the tip of the rod-shaped electrode is disposed in the internal space communicating with each of the plurality of through holes, it is possible to reduce the concentration of the electric field at the tip of the rod-shaped electrode.

[0062] In the antenna according to the above aspect, the inner surface of the second cylindrical portion surrounding the internal space may be formed at a position farther from the central axis of the first electrode than the plurality of through holes. According to the above configuration, since the distance between the tip of the rod-shaped electrode and the inner surface of the second cylindrical portion surrounding the internal space in which the tip of the rod-shaped electrode is disposed increases, it is possible to further reduce the concentration of the electric field at the tip of the rod-shaped electrode.

[0063] The antenna according to the above aspect may further include a tubular insulating element into which the first electrode and the second electrode are inserted and which is connected to each of the adjacent antenna elements. According to the above configuration, each of the adjacent antenna elements can be insulated by the insulating element.

[0064] In the antenna according to the above aspect, the first electrode has a first connection portion that is a portion connected to one of the antenna elements. The first cylindrical portion and the second cylindrical portion are formed of an integral member, and the first connection portion may be provided so as to be separable from the integral member. According to the above configuration, since the first connection portion is provided so as to be separable from the integral member, when assembling the antenna, the first connection portion can be separated from the integral member to confirm the positional relationship between the through hole and the rod-shaped electrode.

[0065] In the antenna according to the above aspect, the first electrode and the second electrode may be fixed to the insulating element by a fixing member. According to the above configuration, by fixing the first electrode and the second electrode to the insulating element, the positions of the central axis of the first electrode and the central axis of the second electrode can be accurately determined. Thereby, the relative position between the through hole formed in the first electrode and the central axis of the rod-shaped electrode can be accurately determined.

[0066] In the antenna according to the above aspect, the second electrode has a second connection portion which is a portion connected to the other side of the antenna element, and the rod-shaped electrode has a flange portion substantially orthogonal to the extending direction of the rod-shaped electrode, and a protrusion portion connected to the flange portion, and the flange portion and the protrusion portion constitute the rear end of the rod-shaped electrode, and the rod-shaped electrode may be connected to the second connection portion by inserting the protrusion portion into the second connection portion.

[0067] According to the above configuration, by inserting the protrusion portion into the second connection portion, the length of the portion of the rod-shaped electrode surrounded by the through hole can be accurately determined. Further, since the flange portion is substantially orthogonal to the extending direction of the rod-shaped electrode, the rod-shaped electrode can be easily connected to the second connection portion so that the extending direction of the rod-shaped electrode and the extending direction of the through hole coincide with each other.

[0068] The antenna according to one aspect of the present disclosure includes the above antenna.

[0069] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

Explanation of Reference Numerals

[0070] 1, 1A Plasma processing apparatus 3, 3A, 3B Antenna 31, 31A, 31B Antenna element 32 Capacitance element 32A, 52A, 62A First electrode 32B Second electrode 32C and 52C rod electrodes 32D Second connection part 33 Insulating element 34 and 35 Fixing members 321A and 621A First cylindrical part 321B, 521B and 621B Second cylindrical part 322 Flange part 323 Protrusion 621C First connection part CL Cooling liquid H1 Through hole P1 Plasma SP3 Internal space SP2 Space

Claims

1. An antenna that extends along an axis and emits electromagnetic waves for generating plasma by passing a high-frequency current through it, at least two antenna elements arranged sequentially along said axis; at least one capacitive element disposed between two adjacent antenna elements; the capacitance element has a first electrode electrically connected to one of the adjacent antenna elements and a second electrode electrically connected to the other of the adjacent antenna elements, the first electrode has a first cylindrical portion extending in the axial direction, the second electrode has a plurality of rod-shaped electrodes extending in the axial direction, An antenna characterized in that a plurality of through holes extending in the axial direction are formed inside the first cylindrical portion, the through holes being arranged in a row along the side surface of the first cylindrical portion and into which each of a plurality of the rod-shaped electrodes is inserted.

2. 2. The antenna according to claim 1, wherein a cooling liquid flows in a space between the rod-shaped electrode and an inner surface of the first cylindrical portion defining the through hole.

3. the first electrode has a second cylindrical portion connected to the first cylindrical portion so that a side surface of the second cylindrical portion is continuous with the first cylindrical portion; an internal space communicating with each of the through holes is formed inside the second cylindrical portion, 3. The antenna according to claim 1, wherein the tip of each of the rod-shaped electrodes is disposed in the internal space.

4. 4. The antenna according to claim 3, wherein the inner surface of the second cylindrical portion surrounding the internal space is formed at a position farther from the central axis of the first electrode than the plurality of through holes.

5. 5. The antenna according to claim 3, further comprising tubular insulating elements connected to adjacent antenna elements, each of which has the first electrode and the second electrode inserted therein.

6. the first electrode has a first connection portion that is a portion that is connected to one of the antenna elements, 6. The antenna according to claim 5, wherein the first cylindrical portion and the second cylindrical portion are configured as an integral member, and the first connecting portion is provided so as to be separable from the integral member.

7. 7. The antenna according to claim 5, wherein the first electrode and the second electrode are fixed to the insulating element by a fixing member.

8. the second electrode has a second connection portion that is a portion that is connected to the other of the antenna elements, the rod-shaped electrode has a flange portion that is substantially perpendicular to an extension direction of the rod-shaped electrode, and a protrusion portion that is connected to the flange portion; the flange portion and the protrusion portion constitute a rear end of the rod-shaped electrode, The antenna according to claim 1 , wherein the rod-shaped electrode is connected to the second connection portion by inserting the protrusion into the second connection portion.

9. A plasma processing apparatus comprising the antenna according to claim 1 .

Images