JP6341329B1 - Antenna for generating plasma and plasma processing apparatus including the same - Google Patents

Abstract

The present invention reduces the impedance of an antenna and eliminates a gap generated between an electrode constituting a capacitor and a dielectric. An antenna 3 for generating inductively coupled plasma P, which is provided between at least two conductor elements 31 and conductor elements 31 adjacent to each other, and insulates the conductor elements 31 from each other. An element 32 and a capacitive element 33 electrically connected in series with a conductor element 31 adjacent to each other are provided, and the capacitive element 33 is a first electrode 33A electrically connected to one of the conductor elements 21 adjacent to each other. And a second electrode 33B electrically connected to the other of the conductor elements 31 adjacent to each other, and a liquid dielectric filling the space between the first electrode 33A and the second electrode 33B. Yes. [Selection] Figure 2

Description

  The present invention relates to an antenna for generating an inductively coupled plasma when a high-frequency current is supplied, and a plasma processing apparatus including the antenna.

  2. Description of the Related Art Conventionally, a plasma processing apparatus has been proposed in which a high-frequency current is passed through an antenna, an inductively coupled plasma (abbreviated as ICP) is generated by an induced electric field generated by the antenna, and the substrate W is processed using the inductively coupled plasma. Yes.

  In this type of plasma processing apparatus, when the antenna is lengthened to cope with a large substrate, the impedance of the antenna increases, thereby generating a large potential difference between both ends of the antenna. As a result, there is a problem that plasma uniformity such as plasma density distribution, potential distribution, and electron temperature distribution is deteriorated due to the influence of the large potential difference, and the uniformity of substrate processing is also deteriorated. In addition, when the impedance of the antenna increases, there is a problem that it is difficult for a high-frequency current to flow through the antenna.

  In order to solve such a problem, as shown in Patent Document 1, a plurality of metal pipes are connected with a hollow insulator interposed between adjacent metal pipes, and are connected to the outer periphery of the hollow insulator. A device in which a capacitor, which is a capacitive element, is arranged. The capacitor is electrically connected in series to the metal pipes on both sides of the hollow insulator, the first electrode electrically connected to the metal pipe on one side of the hollow insulator, and the other side of the hollow insulator A second electrode that is electrically connected to the first metal pipe and overlaps the first electrode, and a dielectric sheet disposed between the first electrode and the second electrode.

Japanese Patent Laying-Open No. 2006-72168

  However, since the capacitor has a laminated structure of the first electrode, the dielectric sheet, and the second electrode, a gap may be generated between the electrode and the dielectric. If so, there is a possibility of arc discharge occurring in this gap, which may lead to deterioration of the capacitor, so there is room for improvement in the capacitor structure.

  Here, in order to prevent a gap from being generated between the electrode and the dielectric, it is conceivable to apply an adhesive on both surfaces of the dielectric sheet to adhere the electrode. However, the electrical performance of the adhesive changes the performance of the dielectric sheet, making it difficult to produce a necessary capacitance value.

  It is also conceivable to provide a structure that presses the gap between the electrode and the dielectric from the periphery. However, the provision of the pressing structure complicates the structure around the antenna and may deteriorate the uniformity of plasma generated around the antenna.

  Accordingly, the present invention has been made to solve the above-described problems. A capacitive element is incorporated in an antenna to reduce the impedance of the antenna, and a gap generated between an electrode constituting the capacitive element and a dielectric is eliminated. Is the main issue.

  That is, the antenna for generating plasma according to the present invention is an antenna for generating plasma by flowing a high-frequency current, and is provided between at least two conductor elements and the conductor elements adjacent to each other. An insulating element that insulates the conductive elements; and a capacitive element electrically connected in series with the conductive elements adjacent to each other, wherein the capacitive element is electrically connected to one of the conductive elements adjacent to each other. A first electrode and a second electrode electrically connected to the other of the conductor elements adjacent to each other and disposed opposite to the first electrode; the first electrode and the second electrode; And a dielectric filling the space between the electrodes, wherein the dielectric is a liquid.

In such a plasma generating antenna, since the capacitive element is electrically connected in series to the conductor elements adjacent to each other via the insulating element, the combined reactance of the antenna can be simply described as inductive reactance. Since the capacitive reactance is subtracted from the antenna impedance, the antenna impedance can be reduced. As a result, even when the antenna is lengthened, an increase in impedance can be suppressed, high-frequency current can easily flow through the antenna, and plasma can be generated efficiently.
In particular, according to the present invention, since the space between the first electrode and the second electrode is filled with the liquid dielectric, it is possible to eliminate the gap generated between the electrode constituting the capacitive element and the dielectric. . As a result, arc discharge that can occur in the gap between the electrode and the dielectric can be eliminated, and damage to the capacitive element due to arc discharge can be eliminated. In addition, the capacitance value can be accurately set from the distance between the first electrode and the second electrode, the facing area, and the relative dielectric constant of the liquid dielectric without considering the gap. Furthermore, the structure for pressing the electrode and the dielectric for filling the gap can be eliminated, and the structure around the antenna due to the pressing structure can be prevented from being complicated and the uniformity of plasma caused thereby can be prevented.

  In order to further simplify the peripheral structure of the antenna and improve the uniformity of the plasma, the insulating element has a tubular shape, and the capacitive element is provided inside the insulating element. desirable.

In order to cool the antenna and stably generate plasma, the conductor element and the insulating element are formed in a tubular shape, and a coolant is circulated inside the conductor element and the insulating element. Conceivable. In this configuration, it is preferable that the cooling liquid is supplied to a space between the first electrode and the second electrode so that the cooling liquid is the dielectric.
By using the coolant as a dielectric, it is not necessary to prepare a dielectric separately from the coolant, and the first electrode and the second electrode can be cooled. Usually, the cooling liquid is adjusted to a constant temperature by a temperature control mechanism. By using this cooling liquid as a dielectric, it is possible to suppress a change in relative permittivity due to a temperature change and suppress a change in capacitance value. Further, when water is used as the coolant, the relative permittivity of water is about 80 (20 ° C.), which is larger than the dielectric sheet made of resin, so that a capacitive element that can withstand high voltage can be configured. it can.

As a specific embodiment of each electrode, each electrode has a flange portion that is in electrical contact with an end portion of the conductor element on the insulating element side, and extends from the flange portion to the insulating element side. It is desirable to have an extension part.
If it is this structure, the opposing area between electrodes can be set with an extension part, enlarging a contact area with a conductor element by a flange part.

It is desirable that the extending portions of the electrodes have a tubular shape and are arranged coaxially with each other.
With this configuration, it is possible to generate plasma with good uniformity by making the distribution of the high-frequency current flowing through the conductor element uniform in the circumferential direction while increasing the facing area between the electrodes.

It is desirable that the flange portion of each electrode is fitted in a recess formed in an end surface in the axial direction of the insulating element.
If it is this structure, the relative position of the extension part of each electrode can be determined by fitting a flange part to the recessed part of an insulation element, and the assembly can be made easy.

The plasma processing apparatus according to the present invention includes a vacuum vessel that is evacuated and into which a gas is introduced, an antenna disposed in the vacuum vessel, and a high-frequency power source that causes a high-frequency current to flow through the antenna. The generated plasma is used to treat the substrate, and the antenna has the above-described configuration.
According to this plasma processing apparatus, plasma with good uniformity can be efficiently generated by the antenna described above, so that the uniformity and efficiency of substrate processing can be improved.

  In order to perform processing on a large-area substrate in this plasma processing apparatus, it is conceivable to include a plurality of the antennas. In this case, both ends of the antenna extend out of the vacuum container, and in the adjacent antennas, the end of one antenna and the end of the other antenna are electrically connected by a connecting conductor. Thus, it is desirable that high frequency currents in opposite directions flow through the antennas adjacent to each other.

  It is desirable that the connection conductor has a flow path inside, and a coolant flows through the flow path.

A coolant flows inside the conductor element and the insulating element, and in the antennas adjacent to each other, the coolant that flows through one of the antennas flows to the other antenna through the flow path of the connection conductor. It is desirable that
With this configuration, both the antenna and the connection conductor can be cooled by a common coolant. In addition, since a plurality of antennas can be cooled by a single flow path, the configuration of the circulation flow path for circulating the coolant can be simplified. In addition, when the flow path of the antenna and the flow path of the connection conductor become long, the lowering of the dielectric constant on the downstream side may occur due to the rise of the coolant. For this reason, the number of antennas connected by the connection conductor is set in consideration of the temperature rise of the coolant, and for example, the number of antennas is about four.

When the power feeding side end and the ground side end of the two antennas are connected by a connection conductor, an increase in impedance occurs due to the connection conductor. As a result, there is a possibility that the potential at the end on the power supply side will rise relative to the end on the most ground side due to energization of the high-frequency current, or the voltage may rise or fall depending on the impedance of the connecting conductor. is there. This causes non-uniformity of the generated plasma.
In order to preferably solve this problem, the connection conductor includes one conductor portion connected to one of the antennas adjacent to each other, and the other conductor portion connected to the other antenna, It is desirable to have a capacitive element electrically connected in series to the one conductor part and the other conductor part. Thus, by providing a capacitive element in a connection conductor, the impedance of a connection conductor can be made into zero equivalent, and the increase in the impedance by a connection conductor can be eliminated.

Furthermore, a plasma processing apparatus according to the present invention includes a processing chamber that is evacuated and into which a gas is introduced, an antenna according to any one of claims 1 to 6 disposed outside the processing chamber, and a high-frequency wave to the antenna. A high-frequency power source for supplying a current, and configured to perform processing on the substrate in the processing chamber using plasma generated by the antenna.
According to this plasma processing apparatus, conditions such as the pressure of the processing chamber and conditions such as the pressure of the antenna chamber in which the antenna is disposed can be individually controlled, and plasma can be generated efficiently, and the substrate Can be processed efficiently.

  In order to perform processing on a substrate having a large area in this plasma processing apparatus, a plurality of the antennas are provided, and in the antennas adjacent to each other, one end of the antenna and the other end of the antenna Are preferably electrically connected by a connecting conductor so that high-frequency currents in opposite directions flow through the adjacent antennas.

  According to the present invention configured as described above, the impedance of the antenna can be reduced by incorporating the capacitive element into the antenna, and the gap generated between the electrode and the dielectric constituting the capacitive element can be eliminated. Can be generated efficiently.

It is a longitudinal cross-sectional view which shows typically the structure of the plasma processing apparatus of this embodiment. It is an expanded sectional view showing typically the peripheral structure of the capacitive element in the antenna of the embodiment. It is an expanded sectional view showing typically the capacitive element of modification. It is an expanded sectional view showing typically the capacitive element of modification. It is an expanded sectional view showing typically the peripheral structure of the capacitive element in the antenna of a modified embodiment. It is a cross-sectional view which shows typically the structure of the plasma processing apparatus of deformation | transformation embodiment. It is a cross-sectional view which shows typically the structure of the plasma processing apparatus of deformation | transformation embodiment. It is a figure which shows typically the structure of the plasma processing apparatus of deformation | transformation embodiment.

  Hereinafter, an embodiment of a plasma processing apparatus according to the present invention will be described with reference to the drawings.

<Device configuration>
The plasma processing apparatus 100 of this embodiment performs processing on the substrate W using inductively coupled plasma P. Here, the board | substrate W is a board | substrate for flat panel displays (FPD), such as a liquid crystal display and an organic electroluminescent display, a flexible board | substrate for flexible displays, etc., for example. The processing applied to the substrate W is, for example, film formation by plasma CVD, etching, ashing, sputtering, or the like.

  The plasma processing apparatus 100 is a plasma CVD apparatus when a film is formed by plasma CVD, a plasma etching apparatus when etching is performed, a plasma ashing apparatus when ashing is performed, and a plasma sputtering apparatus when sputtering is performed. be called.

  Specifically, as shown in FIG. 1, the plasma processing apparatus 100 includes a vacuum vessel 2 that is evacuated and into which a gas 7 is introduced, a linear antenna 3 that is disposed in the vacuum vessel 2, and a vacuum vessel 2. And a high frequency power source 4 for applying a high frequency for generating the inductively coupled plasma P to the antenna 3. When a high frequency is applied to the antenna 3 from the high frequency power source 4, a high frequency current IR flows through the antenna 3, an induction electric field is generated in the vacuum chamber 2, and inductively coupled plasma P is generated.

  The vacuum vessel 2 is, for example, a metal vessel, and the inside thereof is evacuated by the evacuation device 6. The vacuum vessel 2 is electrically grounded in this example.

The gas 7 is introduced into the vacuum vessel 2 through, for example, a flow rate regulator (not shown) and a plurality of gas inlets 21 arranged in a direction along the antenna 3. The gas 7 may be made in accordance with the processing content applied to the substrate W. For example, when film formation is performed on the substrate W by the plasma CVD method, the gas 7 is a source gas or a gas obtained by diluting it with a diluent gas (for example, H ₂ ). More specifically, when the source gas is SiH ₄ , the Si film is formed, when SiH ₄ + NH ₃ is used, the SiN film is formed, when SiH ₄ + O ₂ is used, the SiO ₂ film is formed, and when SiF ₄ + N ₂ is used, the SiN film is formed. : F films (fluorinated silicon nitride films) can be formed on the substrate W, respectively.

  A substrate holder 8 that holds the substrate W is provided in the vacuum container 2. As in this example, a bias voltage may be applied to the substrate holder 8 from the bias power supply 9. The bias voltage is, for example, a negative DC voltage, a negative bias voltage, or the like, but is not limited thereto. With such a bias voltage, for example, the energy when positive ions in the plasma P are incident on the substrate W can be controlled to control the crystallinity of the film formed on the surface of the substrate W. . A heater 81 for heating the substrate W may be provided in the substrate holder 8.

  The antenna 3 is disposed above the substrate W in the vacuum container 2 so as to be along the surface of the substrate W (for example, substantially parallel to the surface of the substrate W). The number of antennas 3 arranged in the vacuum vessel 2 may be one or plural.

  Near both ends of the antenna 3, the opposite side walls of the vacuum container 2 are respectively penetrated. Insulating members 11 are respectively provided at portions where both ends of the antenna 3 penetrate outside the vacuum vessel 2. Both end portions of the antenna 3 pass through the insulating members 11, and the through portions are vacuum-sealed by, for example, packing 12. Each insulating member 11 and the vacuum vessel 2 are also vacuum-sealed by, for example, packing 13. The insulating member 11 is made of, for example, ceramics such as alumina, quartz, engineering plastics such as polyphenine sulfide (PPS), polyether ether ketone (PEEK), or the like.

  Further, a portion of the antenna 3 located in the vacuum vessel 2 is covered with a straight tubular insulating cover 10. Both ends of the insulating cover 10 are supported by insulating members 11. In addition, it is not necessary to seal between the both ends of the insulating cover 10 and the insulating member 11. This is because even if the gas 7 enters the space in the insulating cover 10, the space P is small and the electron moving distance is short, so that plasma P is not normally generated in the space. The material of the insulating cover 10 is, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, silicon or the like.

  By providing the insulating cover 10, it is possible to prevent charged particles in the plasma P from entering the metal pipe 31 constituting the antenna 3, so that charged particles (mainly electrons) enter the metal pipe 31. An increase in plasma potential can be suppressed, and metal contamination (metal contamination) on the plasma P and the substrate W caused by sputtering of the metal pipe 31 by charged particles (mainly ions) can be suppressed. .

  A high-frequency power source 4 is connected to a feeding end portion 3a that is one end portion of the antenna 3 via a matching circuit 41, and a termination portion 3b that is the other end portion is directly grounded. The terminal end 3b may be grounded via a capacitor or a coil.

  With the above configuration, the high-frequency current IR can flow from the high-frequency power source 4 to the antenna 3 through the matching circuit 41. The high frequency is, for example, a general 13.56 MHz, but is not limited thereto.

  The antenna 3 has a hollow structure having a flow path through which the coolant CL flows. Specifically, as shown in FIG. 2, the antenna 3 is provided between at least two tubular metal conductor elements 31 (hereinafter referred to as “metal pipes 31”) and metal pipes 31 adjacent to each other. In addition, a tubular insulating element 32 (hereinafter referred to as “insulating pipe 32”) that insulates the metal pipes 31 and a capacitor 33 that is a capacitive element electrically connected in series with the adjacent metal pipes 31 are provided. ing.

  In the present embodiment, the number of metal pipes 31 is two, and the number of insulating pipes 32 and capacitors 33 is one each. In the following description, one metal pipe 31 is also referred to as “first metal pipe 31A”, and the other metal pipe is also referred to as “second metal pipe 31B”. The antenna 3 may have a configuration including three or more metal pipes 31. In this case, the number of the insulating pipes 32 and the capacitors 33 is one less than the number of the metal pipes 31. Become.

  The coolant CL circulates through the antenna 3 through a circulation channel 14 provided outside the vacuum vessel 2, and the circulation channel 14 has heat for adjusting the coolant CL to a constant temperature. A temperature control mechanism 141 such as an exchanger and a circulation mechanism 142 such as a pump for circulating the coolant CL in the circulation flow path 14 are provided. As the cooling liquid CL, high resistance water is preferable from the viewpoint of electrical insulation, for example, pure water or water close thereto is preferable. In addition, a liquid refrigerant other than water, such as a fluorine-based inert liquid, may be used.

  The metal pipe 31 has a straight tube shape in which a linear flow path 31x in which the coolant CL flows is formed. And the external thread part 31a is formed in the outer peripheral part of the longitudinal direction at least one end part of the metal pipe 31. As shown in FIG. Although the metal pipe 31 of this embodiment forms the edge part in which the external thread part 31a was formed, and other members by separate parts, they may be joined, but you may form from a single member. In order to make the parts common with the configuration in which the plurality of metal pipes 31 are connected, it is desirable that the male pipe portions 31a be formed at both ends in the longitudinal direction of the metal pipe 31 so as to be compatible. The material of the metal pipe 31 is, for example, copper, aluminum, alloys thereof, stainless steel, or the like.

  The insulating pipe 32 has a straight tube shape in which a linear flow path 32x in which the cooling liquid CL flows is formed. Then, on the side peripheral walls at both ends in the axial direction of the insulating pipe 32, female screw portions 32 a that are screwed and connected to the male screw portion 31 a of the metal pipe 31 are formed. Moreover, the recessed part 32b for fitting each electrode 33A, 33B of the capacitor | condenser 33 to the axial direction center side rather than the internal thread part 32a is formed in the side peripheral wall of the axial direction both ends of the insulation pipe 32 over the whole circumferential direction. Is formed. Although the insulation pipe 32 of this embodiment is formed from a single member, it is not restricted to this. The material of the insulating pipe 32 is, for example, alumina, fluororesin, polyethylene (PE), engineering plastic (for example, polyphenine sulfide (PPS), polyether ether ketone (PEEK), etc.).

  The capacitor 33 is provided inside the insulating pipe 32. Specifically, the capacitor 33 is provided in the flow path 32x through which the coolant CL of the insulating pipe 32 flows.

  Specifically, the capacitor 33 includes a first electrode 33A electrically connected to one of the adjacent metal pipes 31 (first metal pipe 31A) and the other of the adjacent metal pipes 31 (second metal). A space between the first electrode 33A and the second electrode 33B, the second electrode 33B being electrically connected to the pipe 31B) and disposed opposite to the first electrode 33A. Is configured to be filled with the coolant CL. That is, the coolant CL that flows in the space between the first electrode 33 </ b> A and the second electrode 33 </ b> B becomes a dielectric that constitutes the capacitor 33.

  Each of the electrodes 33A and 33B has a substantially rotating body shape, and a main flow path 33x is formed at the center along the central axis. Specifically, each of the electrodes 33A and 33B includes a flange portion 331 that electrically contacts an end portion of the metal pipe 31 on the insulating pipe 32 side, and an extending portion 332 that extends from the flange portion 331 to the insulating pipe 32 side. have. In each of the electrodes 33A and 33B of the present embodiment, the flange portion 331 and the extension portion 332 may be formed from a single member, or may be formed by separate parts and joined together. The material of the electrodes 33A and 33B is, for example, aluminum, copper, or an alloy thereof.

  The flange portion 331 is in contact with the end portion of the metal pipe 31 on the insulating pipe 32 side over the entire circumferential direction. Specifically, the axial end surface of the flange portion 331 contacts the tip end surface of a cylindrical contact portion 311 formed at the end portion of the metal pipe 31 over the entire circumferential direction, and the contact portion of the metal pipe 31. Electrical contact is made with the end surface of the metal pipe 31 via a ring-shaped multi-face contact 15 provided on the outer periphery of 311. The flange portion 331 may be in electrical contact with the metal pipe 31 by any one of them.

  The flange portion 331 has a plurality of through holes 331h in the thickness direction. By providing the through hole 331 h in the flange portion 331, the flow resistance of the coolant CL by the flange portion 331 is reduced, and the retention of the coolant CL in the insulating pipe 32 and bubbles in the insulating pipe 32 are generated. It can be prevented from accumulating.

  The extending part 332 has a cylindrical shape, and a main flow path 33x is formed therein. The extension part 332 of the first electrode 33A and the extension part 332 of the second electrode 33B are arranged coaxially with each other. That is, the extension part 332 of the second electrode 33B is provided in a state of being inserted into the extension part 332 of the first electrode 33A. Thereby, a cylindrical space along the flow path direction is formed between the extending portion 332 of the first electrode 33A and the extending portion 332 of the second electrode 33B.

  Each of the electrodes 33 </ b> A and 33 </ b> B configured in this manner is fitted in a recess 32 b formed on the side peripheral wall of the insulating pipe 32. Specifically, the first electrode 33A is fitted in the recess 32b formed on one end side in the axial direction of the insulating pipe 32, and the second electrode is inserted in the recess 32b formed on the other end side in the axial direction of the insulating pipe 32. 33B is fitted. Thus, by fitting each electrode 33A, 33B to each recessed part 32b, the extension part 332 of the 1st electrode 33A and the extension part 332 of the 2nd electrode 33B are mutually arrange | positioned coaxially. Further, when the end face of the flange portion 331 of each electrode 33A, 33B is in contact with the surface facing the axially outer side of each recess 32b, the extension portion of the second electrode 33B with respect to the extension portion 332 of the first electrode 33A An insertion dimension of 332 is defined.

Further, the electrodes 33A and 33B are fitted into the recesses 32b of the insulating pipe 32, and the male threaded portion 31a of the metal pipe 31 is screwed into the female threaded portion 32a of the insulating pipe 32, whereby the contact portion of the metal pipe 31 is contacted. The tip surface of 311 comes into contact with the flange portion 331 of the electrodes 33A and 33B, and the electrodes 33A and 33B are sandwiched and fixed between the insulating pipe 32 and the metal pipe 31. As described above, the antenna 3 according to this embodiment has a structure in which the metal pipe 31, the insulating pipe 32, the first electrode 33A, and the second electrode 33B are coaxially arranged. In addition, the connection part of the metal pipe 31 and the insulation pipe 32 has a seal structure with respect to the vacuum and the coolant CL. The seal structure of the present embodiment is realized by a seal member 16 such as packing provided at the proximal end portion of the male screw portion 31a. In addition, you may use the taper screw structure for pipes.
As described above, since the seal structure between the metal pipe 31 and the insulating pipe 32 and the electrical contact between the metal pipe 31 and each of the electrodes 33A and 33B are performed together with the fastening of the male screw portion 31a and the female screw portion 32a, the assembly work is performed. It becomes very simple.

  In this configuration, when the coolant CL flows from the first metal pipe 31A, the coolant CL flows to the second electrode 33B side through the main channel 33x and the through hole 331h of the first electrode 33A. The coolant CL that has flowed to the second electrode 33B side flows to the second metal pipe 31B through the main flow path 33x and the through hole 331h of the second electrode 33B. At this time, the cylindrical space between the extending portion 332 of the first electrode 33A and the extending portion 332 of the second electrode 33B is filled with the cooling liquid CL, and the cooling liquid CL becomes a dielectric and becomes a capacitor. 33 is configured.

<Effect of this embodiment>
According to the plasma processing apparatus 100 of the present embodiment configured as described above, the capacitor 33 is electrically connected in series to the metal pipes 31 adjacent to each other via the insulating pipe 32. Therefore, the combined reactance of the antenna 3 is In short, since the capacitive reactance is subtracted from the inductive reactance, the impedance of the antenna 3 can be reduced. As a result, even when the antenna 3 is lengthened, an increase in impedance can be suppressed, high-frequency current can easily flow through the antenna 3, and inductively coupled plasma P can be generated efficiently.

  In particular, according to the present embodiment, since the space between the first electrode 33A and the second electrode 33B is filled with the liquid dielectric (cooling liquid CL), the electrodes 33A and 33B constituting the capacitor 33 and the dielectric It is possible to eliminate gaps between the bodies. As a result, arc discharge that can occur in the gap between the electrodes 33A and 33B and the dielectric can be eliminated, and damage to the capacitor 33 due to arc discharge can be eliminated. Further, the distance between the extending portion 332 of the first electrode 33A and the extending portion 332 of the second electrode 33B, the facing area, and the relative dielectric of the liquid dielectric (cooling liquid CL) without considering the gap. The capacitance value can be accurately set from the rate. Further, the structure for pressing the electrodes 33A and 33B and the dielectric for filling the gaps can be eliminated, and the structure around the antenna due to the pressing structure and the deterioration of the uniformity of the plasma P caused thereby can be prevented. be able to.

  Since the cooling liquid CL for cooling the antenna 3 is a dielectric, it is not necessary to prepare a dielectric separately from the cooling liquid CL, and the electrodes 33A and 33B can be cooled. In addition, the cooling liquid CL is normally adjusted to a constant temperature by the temperature adjustment mechanism 141. By using this cooling liquid CL as a dielectric, the change in the dielectric constant due to the temperature change is suppressed, and the change in the capacitance value is suppressed. Can be suppressed. Further, when water is used as the cooling liquid CL, the relative dielectric constant of water is about 80 (20 ° C.), which is larger than the dielectric sheet made of resin, so that the capacitor 33 that can withstand high voltage is formed. Can do. Here, since the dielectric constant is large, the capacitor 33 can obtain a sufficient capacitance value even if the capacitor 33 has a two-cylinder structure including two extending portions 332. Therefore, each electrode 33A, 33B can be manufactured while the perpendicularity of the extending part 332 with respect to the flange part 331 of each electrode 33A, 33B is improved, and the capacitance value can be set with high accuracy. In addition, there is a possibility that impurities may be mixed in by electrolysis of water, but it can be removed by providing a filter such as an ion exchange membrane filter on the circulation channel 14, and the capacitance value of the capacitor 33 changes. Can be suppressed.

<Other modified embodiments>
The present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the capacitor 33 has a two-cylinder structure including two cylindrical extending portions. However, as shown in FIG. 3, three or more cylindrical extending portions 332 are coaxially arranged. It may be arranged. In this case, the extending part 332 of the first electrode 33A and the extending part 332 of the second electrode 33B are arranged alternately. In FIG. 3, of the three extending portions 332, the inner and outer two are the extending portions 332 of the first electrode 33A, and the middle one is the extending portion 332 of the second electrode 33B. With this configuration, the facing area can be increased without increasing the axial dimension of the capacitor 33.

  Further, as shown in FIG. 4, a part of the tip corner portion 332a of the extension portion 332 is cut into a taper shape so as to alleviate electric field concentration at the tip corner portion of the extension portion 332 serving as the counter electrode of the capacitor 33. May be missing. Specifically, the inner peripheral surface of the tip corner portion 332a of the extension portion 332 of the first electrode 33A is cut out in a tapered shape, and the outer peripheral surface of the tip corner portion 332a of the extension portion 332 of the second electrode 33B. Cut out into a tapered shape.

  Further, the contact between the electrodes 33A and 33B and the metal pipe 31 is not limited to the contact between the end faces, but the contact terminals 333 are provided on the electrodes 33A and 33B as shown in FIG. You may comprise so that it may contact. 5 is provided with a contact terminal 333 protruding axially outward from the flange portion 331 of the electrodes 33A and 33B, and the contact terminal 333 is in press contact with the outer peripheral surface of the contact portion 311 of the metal pipe 31. is there. In this configuration, the relative positions of the electrodes 33A and 33B are defined by the surface of the insulating pipe 32 facing the outside in the axial direction of the recess 32b.

  In the embodiment, the capacitor is housed in the insulating pipe. However, the capacitor may be provided outside the insulating pipe. For example, the first electrode and the second electrode constituting the capacitor are provided on the outer periphery of the insulating pipe, and a liquid dielectric is filled between the electrodes. Alternatively, the first electrode and the second electrode may be electrically connected to the metal pipe while the electrodes are separated from the insulating pipe. In these configurations, the liquid dielectric may be a coolant supplied by a branch flow path branched from the internal flow path of the antenna, or may be a liquid dielectric supplied by a separate path from the coolant. There may be. Further, a liquid dielectric may be sealed between the first electrode and the second electrode. In the case of sealing, it is necessary to provide a temperature adjustment mechanism for adjusting the temperature of the dielectric material of the liquid to be constant.

  Furthermore, as shown in FIG. 6, in the plasma processing apparatus 100 having a plurality of antennas 3, both end portions of each antenna 3 are extended out of the vacuum vessel 2, and the antennas 3 adjacent to each other have one antenna 3. The end and the end of the other antenna 3 may be electrically connected by the connection conductor 17. Here, the end portions of the two antennas connected by the connection conductor 17 are end portions located on the same side wall side. Accordingly, the plurality of antennas 3 are configured such that high-frequency currents in opposite directions flow through the antennas 4 adjacent to each other. Thus, by making a plurality of antennas into a single antenna structure by the connection conductor 17, it is possible to easily increase the size of the substrate to be processed.

  And the connection conductor 17 has a flow path inside, and it is comprised so that a cooling fluid may flow into the flow path. Specifically, one end of the connection conductor 17 communicates with the flow path of one antenna 3, and the other end of the connection conductor 17 communicates with the flow path of the other antenna 3. Thereby, in the antennas 3 adjacent to each other, the coolant flowing through one antenna 3 flows to the other antenna 3 through the flow path of the connection conductor 17. Thereby, both the antenna 3 and the connection conductor 17 can be cooled by the common coolant. In addition, since the plurality of antennas 3 can be cooled by one flow path, the configuration of the circulation flow path 14 can be simplified.

  Further, the connection conductor 17 includes one conductor portion 17a connected to one antenna 3 in the antennas 3 adjacent to each other, the other conductor portion 17c connected to the other antenna 3, the one conductor portion 17a and the other conductor portion 17a. And a capacitor 17c which is a capacitive element electrically connected in series to the conductor portion 17b. The configuration of the conductor portions 17a and 17b may be the same as that of the conductor element 31 of the embodiment, for example, and the configuration of the capacitor 17c may be the same as that of the capacitor 33 of the embodiment, for example. By providing the capacitor 17c in the connection conductor 17 in this way, the impedance of the connection conductor 17 can be made equal to zero, and an increase in impedance due to the connection conductor 17 can be eliminated. The capacitance may be adjusted by using the capacitor 17c as a variable capacitor.

  The configuration of the connection conductor 17 is not limited to FIG. 6. For example, as illustrated in FIG. 7, the connection conductor 17 may have a configuration without a capacitive element. In the case of this configuration, in the antennas 3 adjacent to each other, an inductance obtained by combining the feeding-side end 3a of one antenna 3, the ground-side end 3b of the other antenna 3, and the connection conductor 17 is set as another conductor element 31. The same inductive reactance and capacitive reactance are continuously repeated over the plurality of antennas 3 in the same manner as the above-described inductance. As a result, it is possible to eliminate an apparent increase in impedance due to the connection conductor as a whole of the plurality of antennas 3. As a result, uniform plasma P can be generated along the antenna 3 in the length direction and the arrangement direction.

  In the plasma processing apparatus 100 of the above embodiment, the antenna 3 is disposed in the processing chamber of the substrate W. However, as shown in FIG. 8, the antenna 3 may be disposed outside the processing chamber 18. . In this case, the plurality of antennas 3 are arranged in an antenna chamber 20 that is partitioned from the processing chamber 18 by a dielectric window 19 in the vacuum vessel 2. The antenna chamber 20 is evacuated by the evacuation device 21. Here, the plurality of antennas 3 may be connected to each other by the connection conductor 17 as shown in FIG. 6 and FIG. 7 described above, or arranged individually without being connected by the connection conductor 17. It may be a thing. With this plasma processing apparatus 100, conditions such as the pressure in the processing chamber 18 and conditions such as the pressure in the antenna chamber 20 can be individually controlled, and the generation of plasma P can be efficiently performed, and the substrate W can be efficiently generated. Can be processed efficiently.

  In addition, in the above embodiment, the antenna has a linear shape, but may have a curved or bent shape. In this case, the metal pipe may be curved or bent, or the insulating pipe may be curved or bent.

  In addition, the conductor element and the insulating element have a tubular shape having one internal flow path, but may have two or more internal flow paths or have a branched internal flow path. good. Further, the conductive element and / or the insulating element may be solid.

  In the electrode of the embodiment, the extending portion has a cylindrical shape, but may have another rectangular tube shape, a flat plate shape, or a curved or bent plate shape.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Plasma processing apparatus W ... Board | substrate P ... Inductively coupled plasma 2 ... Vacuum container 3 ... Antenna 31 ... Metal pipe (conductor element)
32 ... Insulating pipe (insulating element)
32b ... concave 33 ... capacitor 33A ... first electrode 33B ... second electrode 331 ... flange 332 ... extension part CL ... coolant (liquid dielectric) )
4... High-frequency power source 17... Connection conductor 17 a... One conductor portion 17 b... The other conductor portion 17 c.

Claims (13)

An antenna for generating plasma by flowing high-frequency current,
Comprising at least two conductor elements, an insulating element provided between the conductor elements adjacent to each other to insulate the conductor elements, and a capacitive element electrically connected in series with the conductor elements adjacent to each other;
The capacitive element is electrically connected to one of the conductor elements adjacent to each other and electrically connected to the other of the conductor elements adjacent to each other and is opposed to the first electrode. The antenna is composed of a second electrode arranged in the manner described above and a dielectric that fills a space between the first electrode and the second electrode, and the dielectric is a liquid. The insulating element has a tubular shape,
The antenna according to claim 1, wherein the capacitive element is provided inside the insulating element. The conductor element has a tubular shape,
A coolant flows inside the conductor element and the insulating element;
The antenna according to claim 2, wherein the coolant is the dielectric.   Each said electrode has the flange part which contacts the edge part by the side of the said insulation element in the said conductor element, and the extension part extended to the said insulation element side from the said flange part, The said Claim 2 or 3 The described antenna.   The antenna according to claim 4, wherein the extending portion of each electrode has a tubular shape and is arranged coaxially with each other. The antenna according to claim 4 or 5, wherein the flange portion of each electrode is fitted in a recess formed in an end surface in the axial direction of the insulating element. A vacuum vessel that is evacuated and into which gas is introduced;
The antenna according to any one of claims 1 to 6 disposed in the vacuum vessel;
A high-frequency power source for supplying a high-frequency current to the antenna;
A plasma processing apparatus configured to perform processing on a substrate using plasma generated by the antenna. A plurality of the antennas,
Both end portions of the antenna extend out of the vacuum container,
In the adjacent antennas, the end of one antenna and the end of the other antenna are electrically connected by a connecting conductor so that high-frequency currents in opposite directions flow through the adjacent antennas. The plasma processing apparatus according to claim 7, which is configured.   The plasma processing apparatus according to claim 8, wherein the connection conductor has a flow path inside, and a coolant flows through the flow path. A coolant flows inside the conductor element and the insulating element;
The plasma processing apparatus according to claim 9, wherein in the antennas adjacent to each other, the coolant flowing through one of the antennas flows to the other antenna through the flow path of the connection conductor.   The connection conductor includes one conductor portion connected to one of the antennas adjacent to each other, the other conductor portion connected to the other antenna, the one conductor portion, and the other conductor portion. 11. The plasma processing apparatus according to claim 8, further comprising a capacitor element electrically connected in series. A processing chamber that is evacuated and gas is introduced;
The antenna according to any one of claims 1 to 6, which is disposed outside the processing chamber,
A high-frequency power source for supplying a high-frequency current to the antenna;
A plasma processing apparatus configured to perform processing on a substrate in the processing chamber using plasma generated by the antenna. A plurality of the antennas,
In the adjacent antennas, the end of one antenna and the end of the other antenna are electrically connected by a connecting conductor so that high-frequency currents in opposite directions flow through the adjacent antennas. The plasma processing apparatus according to claim 12, which is configured.