Antenna and plasma processing equipment

Abstract

When connecting conductive and insulating elements, damage to the fastening portions of the conductive and insulating elements is suppressed. [Solution] An antenna 3 for which a high-frequency current flows to generate plasma, The device comprises at least two cylindrical conductive elements 31, a cylindrical insulating element 32 provided between adjacent conductive elements 31 to insulate them, a capacitive element 33 electrically connected in series with adjacent conductive elements 31, a male threaded portion 31a formed on one of the conductive elements 31 and the insulating element 32, and a female threaded portion 32a formed on the other of the conductive elements 31 and the insulating element 32, wherein the male threaded portion 31a and the female threaded portion 32a are multi-start threads connecting the conductive elements 31 and the insulating element 32 to each other.

Description

Technical Field

[0001] The present invention relates to an antenna and a plasma processing apparatus provided with the antenna.

Background Art

[0002] Plasma processing apparatuses that process a substrate using inductively coupled plasma (hereinafter also referred to as ICP) have been developed conventionally. In this plasma processing apparatus, a high-frequency current flows, and an antenna for generating ICP is used.

[0003] This type of antenna includes, for example, as shown in Patent Document 1, at least two conductor elements having a cylindrical shape, an insulating element having a cylindrical shape and provided between adjacent conductor elements to insulate those conductor elements, and a capacitor element electrically connected in series with adjacent conductor elements.

[0004] In the above antenna, a screw mechanism is provided intervening between the conductor element and the insulating element to connect them to each other. Specifically, a male screw portion is formed on the outer peripheral portion of the conductor element, and a female screw portion that engages with the male screw portion is formed on the inner side wall of the insulating element. By inserting the conductor element into the insulating element and screwing the male screw portion and the female screw portion, the conductor element and the insulating element are connected.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a plasma processing apparatus where the antenna described above is installed inside the chamber, the antenna is subjected to high temperatures, such as 1000°C, due to the heat from the plasma. Since the insulating element is made of a material with a low heat resistance temperature, such as PEEK, it is difficult to use the antenna in a high-temperature environment. Furthermore, in conventional plasma processing apparatuses, a heater for heating the substrate is sometimes installed inside the chamber, and the antenna is also subjected to high temperatures due to the radiant heat from the heater.

[0007] Therefore, in order to improve the heat resistance of the insulating element, the material of the insulating element is being considered as ceramic. However, since ceramic is susceptible to mechanical impact, if the screw mechanism consists of a single-thread triangular screw, the screw mechanism may be damaged when connecting the conductive element and the insulating element.

[0008] Therefore, the present invention has been made to solve the above-mentioned problems, and its main objective is to suppress damage to the fastening portion of the conductor element and the insulating element when connecting the conductor element and the insulating element. [Means for solving the problem]

[0009] In other words, the antenna according to the present invention is an antenna for generating plasma by passing a high-frequency current through it, and comprises at least two cylindrical conductive elements, an insulating element that is cylindrical and provided between adjacent conductive elements to insulate them, a capacitive element electrically connected in series with adjacent conductive elements, a male screw portion formed on one of the conductive elements and the insulating element, and a female screw portion formed on the other of the conductive element and the insulating element, wherein the male screw portion and the female screw portion are multi-start screws that connect the conductive elements and the insulating element to each other.

[0010] With this type of antenna, by making the male and female threads multi-threaded, the number of threads engaged for the same engagement length is increased compared to a single-threaded triangular screw. This increases the load required to shear the contact portion between the male and female threads. Therefore, when fastening the conductor and insulating elements, damage to the fastening portions of the conductor and insulating elements can be suppressed.

[0011] In a cross-sectional view obtained by cutting the male thread portion and the female thread portion along the axial direction, the top of the thread in the male thread portion and the bottom of the thread groove in the female thread portion are flat. With this configuration, damage to the threads of the male screw portion can be suppressed when fastening the conductive and insulating elements. Therefore, in addition to the male and female threaded portions being multi-start threads, the above configuration further suppresses damage to the fastening portions of the conductor and insulating elements.

[0012] One example is a configuration in which the male threaded portion is formed on the outer circumferential surface of the conductor element, and the female threaded portion is formed on the inner circumferential surface of the insulating element, and the conductor element and the insulating element are connected by inserting the conductor element into the insulating element and screwing the male threaded portion and the female threaded portion together. In this configuration, the conductive element is made of a harder material than the insulating element, and by inserting the conductive element into the insulating element, the processing of the conductive element can be made easier.

[0013] The insulating element may be made of alumina, aluminum nitride, or machinable ceramics. With this configuration, alumina, aluminum nitride, or machinable ceramics have high heat resistance, allowing the antenna to be used in high-temperature environments. In addition, when the screw mechanism connects the conductor element and the insulating element, the force applied to the contact portion between the male and female threads is distributed compared to a single-start screw. This improves the heat resistance of the insulating element while suppressing damage to the fastening portion of the conductor element and the insulating element.

[0014] Another aspect of the present invention is an antenna for generating plasma by passing a high-frequency current, comprising: at least two cylindrical conductive elements; cylindrical insulating elements provided between adjacent conductive elements to insulate them; capacitive elements electrically connected in series with adjacent conductive elements; a male screw portion formed on one of the conductive elements and the insulating element; and a female screw portion formed on the other of the conductive elements and the insulating element, wherein the male screw portion and the female screw portion connect the conductive elements and the insulating element, and in a cross-sectional view obtained by cutting the male screw portion and the female screw portion along the axial direction, the top of the threads of the male screw portion and the bottom of the thread grooves of the female screw portion are flat.

[0015] With this configuration, in a cross-sectional view obtained by cutting the male and female threaded portions along the axial direction, the tops of the threads in the male portion and the bottoms of the thread grooves in the female portion are flat, thus preventing damage to the threads of the male portion when fastening the conductive and insulating elements.

[0016] A plasma processing apparatus may include the antenna, a vacuum vessel in which the antenna is located either inside or outside, and a high-frequency power supply for applying a high-frequency current to the antenna. With this configuration, the same effects and benefits as the antenna described above can be obtained. [Effects of the Invention]

[0017] According to the present invention configured in this manner, damage to the fastening portions of the conductor element and the insulating element can be suppressed when connecting the conductor element and the insulating element. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic longitudinal cross-sectional view showing the configuration of the plasma processing apparatus of this embodiment. [Figure 2] This is an enlarged cross-sectional view schematically showing the peripheral structure of the capacitive element in the antenna of the same embodiment. [Figure 3] It is an enlarged cross-sectional view schematically showing the peripheral structure of a capacitive element in an antenna of another embodiment. [Figure 4] It is an enlarged cross-sectional view schematically showing the peripheral structure of a capacitive element in an antenna of another embodiment.

Embodiments for Carrying out the Invention

[0019] Hereinafter, an embodiment of a plasma processing apparatus according to the present invention will be described with reference to the drawings.

[0020] <Apparatus Configuration> The plasma processing apparatus 100 of this embodiment performs processing on a substrate W using inductively coupled plasma P. Here, the substrate W is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, a flexible substrate for a flexible display, or the like. Further, the processing performed on the substrate W is, for example, film formation by plasma CVD method, etching, ashing, sputtering, or the like.

[0021] Note that when film formation is performed by the plasma CVD method, this plasma processing apparatus 100 is also called a plasma CVD apparatus, when etching is performed, it is called a plasma etching apparatus, when ashing is performed, it is called a plasma ashing apparatus, and when sputtering is performed, it is called a plasma sputtering apparatus.

[0022] Specifically, as shown in FIG. 1, the plasma processing apparatus 100 includes a vacuum chamber 2 that is evacuated and into which gas 7 is introduced, a linear antenna 3 disposed in the vacuum chamber 2, and a high-frequency power supply 4 that applies a high frequency for generating inductively coupled plasma P to the antenna 3 in the vacuum chamber 2. By applying a high frequency from the high-frequency power supply to the antenna 3, a high-frequency current IR flows through the antenna 3, an induced electric field is generated in the vacuum chamber 2, and inductively coupled plasma P is generated.

[0023] The vacuum container 2 is, for example, a metal container, and its interior is evacuated by a vacuum pump 6. In this example, the vacuum container 2 is electrically grounded.

[0024] Gas 7 is introduced into the vacuum vessel 2, for example, via a flow regulator (not shown) and multiple gas inlets 21 formed on the side wall of the vacuum vessel 2. The gas 7 should be appropriate for the processing to be performed on the substrate W. For example, when forming a film on the substrate W by plasma CVD, gas 7 is the raw material gas or a gas obtained by diluting it with a diluent gas (e.g., H2). To give a more specific example, if the raw material gas is SiH4, a Si film can be formed on the substrate W; if it is SiH4 + NH3, a SiN film can be formed; if it is SiH4 + O2, an SiO2 film can be formed; and if it is SiF4 + N2, a SiN:F film (fluorinated silicon nitride film) can be formed.

[0025] Furthermore, a substrate holder 8 for holding the substrate W is provided inside the vacuum chamber 2. As in this example, a bias voltage may be applied to the substrate holder 8 from a bias power supply 9. The bias voltage is, for example, a negative DC voltage or a negative pulse voltage, but is not limited to these. By using such a bias voltage, it is possible to control, for example, the energy of positive ions in the plasma P when they are incident on the substrate W, thereby controlling the degree of crystallinity of the film formed on the surface of the substrate W. A heater 81 for heating the substrate W may also be provided inside the substrate holder 8.

[0026] Antenna 3 is positioned above the substrate W inside the vacuum chamber 2, along the surface of the substrate W (for example, substantially parallel to the surface of the substrate W). There may be one or more antennas 3 placed inside the vacuum chamber 2.

[0027] The ends of the antenna 3 penetrate the opposing side walls of the vacuum container 2. Insulating members 11 are provided at the portions of the antenna 3 that penetrate to the outside of the vacuum container 2. The ends of the antenna 3 pass through each of these insulating members 11, and these penetrations are vacuum-sealed by, for example, a packing 12. The space between each insulating member 11 and the vacuum container 2 is also vacuum-sealed by, for example, a packing 13. The material of the insulating members 11 is, for example, ceramics such as alumina, quartz, or engineering plastics such as polyphenylene sulfide (PPS) or polyetheretherketone (PEEK).

[0028] Furthermore, in the antenna 3, the portion located inside the vacuum vessel 2 is covered by a straight-tube insulating cover 10. Both ends of this insulating cover 10 are supported by insulating members 11. It is not necessary to seal the gap between both ends of the insulating cover 10 and the insulating members 11. This is because even if gas 7 enters the space inside the insulating cover 10, the space is small and the distance electrons travel is short, so plasma P is not usually generated in the space. The material of the insulating cover 10 can be, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, or silicon.

[0029] By providing the insulating cover 10, it is possible to suppress the incidence of charged particles in the plasma P onto the metal pipe 31 that constitutes the antenna 3. This suppresses the rise in plasma potential caused by the incidence of charged particles (mainly electrons) onto the metal pipe 31, and also suppresses metal contamination of the plasma P and substrate W caused by sputtering of the metal pipe 31 by charged particles (mainly ions).

[0030] A high-frequency power supply 4 is connected to the feed end 3a of the antenna 3 via a matching circuit 41, and the other end, the termination 3b, is directly grounded. The feed end 3a may also be connected to the high-frequency power supply 4 via a capacitor or coil, and the termination 3b may also be grounded via a capacitor or coil.

[0031] With the above configuration, a high-frequency current IR can be supplied from the high-frequency power supply 4 to the antenna 3 via the matching circuit 41. The frequency of the high-frequency current IR is, for example, a common 13.56 MHz, but is not limited to this.

[0032] Antenna 3 has a hollow structure with a passage through which coolant CL flows. The coolant CL flows through antenna 3 via a circulation passage 14 provided outside the vacuum container 2. The circulation passage 14 is equipped with a temperature control mechanism 141, such as a heat exchanger, for adjusting the coolant CL to a constant temperature, and a circulation mechanism 142, such as a pump, for circulating the coolant CL in the circulation passage 14. From the viewpoint of electrical insulation, water with high resistance is preferred as the coolant CL, for example, pure water or water close to pure water is preferred. In addition, liquid coolants other than water, such as fluorine-based inert liquids, may also be used.

[0033] Specifically, as shown in Figure 2, the antenna 3 comprises at least two tubular metal conductor elements 31 (hereinafter referred to as "metal pipes 31"), a tubular insulating element 32 (hereinafter referred to as "insulating pipe 32") provided between adjacent metal pipes 31 to insulate them, and a capacitor 33, which is a capacitive element electrically connected in series with adjacent metal pipes 31.

[0034] In this embodiment, there are two metal pipes 31, and one insulating pipe 32 and one capacitor 33. In the following description, one of the metal pipes 31 will also be referred to as the "first metal pipe 31A," and the other metal pipe as the "second metal pipe 31B." The antenna 3 may also have a configuration with three or more metal pipes 31, in which case the number of insulating pipes 32 and capacitors 33 will each be one less than the number of metal pipes 31.

[0035] The metal pipe 31 is a straight tube with a linear flow path 31x formed inside through which a coolant CL flows. A multi-start male thread portion 31a is formed on the outer circumference of at least one end in the longitudinal direction of the metal pipe 31. In this embodiment, as shown in Figure 2, the male thread portion 31a is a multi-start triangular thread. A multi-start thread, as shown in Figure 2, is a thread in which the distance L that the male thread portion 31a advances axially per rotation increases according to the distance P between adjacent vertices on the male thread portion 31a. Here, it is a two-start thread where the distance L is twice the distance P, but it may also be a multi-start thread with three or more vertices. Note that the male thread portion 31a is not limited to a triangular thread as long as it is a multi-start thread, and the vertices of the threads of the male thread portion 31a may be flat when viewed in a cross-sectional view of the male thread portion 31a cut along the axial direction. Specifically, the male threaded portion 31a may be, for example, a multi-thread trapezoidal thread, a multi-thread square thread, or a multi-thread sawtooth thread.

[0036] In this embodiment, the metal pipe 31 has the end portion with the male threaded portion 31a formed on it and the rest of the pipe formed from separate parts and joined together, but it may also be formed from a single piece of material. Furthermore, in order to ensure compatibility with configurations that connect multiple metal pipes 31, it is desirable to form the male threaded portions 31a on both longitudinal ends of the metal pipe 31 to allow for interchangeability. The material of the metal pipe 31 may be, for example, copper, aluminum, alloys thereof, stainless steel, etc.

[0037] The insulating pipe 32 is a straight tube with a linear flow path 32x formed inside through which the coolant CL flows. The insulating pipe 32 is preferably made of a material with higher heat resistance compared to polyetheretherketone (PEEK), such as alumina, aluminum nitride, or machinable ceramics such as Macol.

[0038] Furthermore, female threaded portions 32a, which are multi-start threads, are formed on the side circumferential walls of both axial ends of the insulating pipe 32, and are connected by screwing into the male threaded portions 31a of the metal pipe 31. In this embodiment, as shown in Figure 2, the female threaded portion 32a is a multi-start triangular thread. Note that the female threaded portion 32a is not limited to a triangular thread as long as it is a multi-start thread, and in a cross-sectional view of the female threaded portion 32a cut along the axial direction, the bottom of the thread groove of the female threaded portion 32a may be flat. Specifically, the female threaded portion 32a may be, for example, a multi-start trapezoidal thread, a multi-start square thread, or a multi-start sawtooth thread.

[0039] Furthermore, recesses 32b for fitting the electrodes 33A and 33B of the capacitor 33 are formed along the entire circumference of the side walls at both axial ends of the insulating pipe 32, on the axial side of the female thread portion 32a towards the center. In this embodiment, the insulating pipe 32 is formed from a single material, but is not limited to this.

[0040] The capacitor 33 is located inside the insulating pipe 32, specifically inside the flow path 32x through which the cooling liquid CL of the insulating pipe 32 flows.

[0041] Specifically, the capacitor 33 comprises a first electrode 33A electrically connected to one of two adjacent metal pipes 31 (the first metal pipe 31A), and a second electrode 33B electrically connected to the other of the two adjacent metal pipes 31 (the second metal pipe 31B) and positioned opposite the first electrode 33A. The space between the first electrode 33A and the second electrode 33B is filled with coolant CL. In other words, the coolant CL flowing through the space between the first electrode 33A and the second electrode 33B becomes the dielectric material constituting the capacitor 33.

[0042] Each electrode 33A and 33B has a roughly rotating shape, and a main flow path 33x is formed in the center along its central axis. Specifically, each electrode 33A and 33B has a flange portion 331 that electrically contacts the end of the metal pipe 31 on the insulating pipe 32 side, and an extension portion 332 that extends from the flange portion 331 toward the insulating pipe 32 side. Each electrode 33A and 33B may be formed from a single material for the flange portion 331 and the extension portion 332, or they may be formed from separate parts and joined together. The material of electrodes 33A and 33B may be, for example, aluminum, copper, or alloys thereof.

[0043] The flange portion 331 is in contact with the end of the metal pipe 31 on the insulating pipe 32 side over its entire circumference. Specifically, the axial end face of the flange portion 331 is in contact with the tip surface of the cylindrical contact portion 311 formed at the end of the metal pipe 31 over its entire circumference.

[0044] The extension portion 332 is cylindrical in shape, and the main flow path 33x is formed inside it. The extension portion 332 of the first electrode 33A and the extension portion 332 of the second electrode 33B are arranged coaxially with each other. In other words, the extension portion 332 of the second electrode 33B is inserted into the extension portion 332 of the first electrode 33A. As a result, a cylindrical space is formed between the extension portion 332 of the first electrode 33A and the extension portion 332 of the second electrode 33B, along the direction of the flow path.

[0045] Each electrode 33A and 33B configured in this way is fitted into a recess 32b formed in the inner wall of the insulating pipe 32. Specifically, the first electrode 33A is fitted into a recess 32b formed on one axial end of the insulating pipe 32, and the second electrode 33B is fitted into a recess 32b formed on the other axial end of the insulating pipe 32. By fitting each electrode 33A and 33B into each recess 32b in this way, the extension portion 332 of the first electrode 33A and the extension portion 332 of the second electrode 33B are arranged coaxially with each other. Furthermore, the insertion dimension of the extension portion 332 of the second electrode 33B relative to the extension portion 332 of the first electrode 33A is defined by the contact of the end faces of the flange portions 331 of each electrode 33A and 33B with the axially outward-facing surfaces of each recess 32b.

[0046] Furthermore, by fitting the electrodes 33A and 33B into the recesses 32b of the insulating pipe 32 and screwing the male threaded portion 31a of the metal pipe 31 into the female threaded portion 32a of the insulating pipe 32, the tip surface of the contact portion 311 of the metal pipe 31 contacts the flange portions 331 of the electrodes 33A and 33B, thereby fixing the electrodes 33A and 33B between the insulating pipe 32 and the metal pipe 31. In this way, the antenna 3 of this embodiment has a structure in which the metal pipe 31, insulating pipe 32, first electrode 33A, and second electrode 33B are arranged coaxially.

[0047] In this configuration, when coolant CL flows from the first metal pipe 31A, the coolant CL flows to the second electrode 33B side through the main flow path 33x 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 of the second electrode 33B. At this time, the cylindrical space between the extension portion 332 of the first electrode 33A and the extension portion 332 of the second electrode 33B is filled with coolant CL, and the coolant CL becomes a dielectric, forming the capacitor 33.

[0048] Furthermore, in this embodiment, the connection between the metal pipe 31 and the insulating pipe 32 has a sealing structure against vacuum and coolant CL. This sealing structure is realized by a sealing member 15 such as a packing provided at the base end of the male threaded portion 31a, but a pipe tapered thread structure may also be used, for example.

[0049] With the above-described configuration, the sealing structure between the metal pipe 31 and the insulating pipe 32, and the electrical contact between the metal pipe 31 and each electrode 33A, 33B are performed together with the fastening of the male threaded portion 31a and the female threaded portion 32a, making the assembly work extremely simple.

[0050] In this embodiment, the antenna 3 includes an outward-facing surface 34 provided on one of the metal pipe 31 or the insulating pipe 32, and an inward-facing surface 35 provided on the other of the metal pipe 31 or the insulating pipe 32 that contacts the outward-facing surface 34. These outward-facing surface 34 and inward-facing surface 35 constitute a deflection suppression mechanism that suppresses the bending of the antenna 3.

[0051] First, regarding the inward-facing surface 35, in this embodiment, the inward-facing surface 35 is provided on the inner circumferential surface of the insulating pipe 32 and is formed at a different position from the female thread portion 32a. More specifically, the insulating pipe 32 has a counterbore portion 321 in which the inner wall is counterboreted axially outward from the female thread portion 32a, and the inner circumferential surface of this counterbore portion 321 is the inward-facing surface 35.

[0052] The counterbore portions 321 are formed at both axial ends of the insulating pipe 32, specifically extending from each end opening up to just before the sealing member 15. In other words, the inner diameter of the counterbore portion 321 is larger than that of the portion on the inner circumferential surface of the insulating pipe 32 where the female thread portion 32a and the sealing member 15 are provided, and in this case, it is the portion of the insulating pipe 32 with the largest inner diameter. The inward-facing surface 35 is formed over the entire circumference of the inner circumferential surface of this counterbore portion 321. In other words, this inward-facing surface 35 is a different surface from the surface on the inner circumferential surface of the insulating pipe 32 where the female thread portion 32a and the sealing member 15 are provided, and in this case, it extends along the axial direction of the insulating pipe 32 (substantially parallel to the axial direction).

[0053] On the other hand, the outward-facing surface 34 in this embodiment is provided on the outer circumferential surface of the metal pipe 31 and is formed at a different position from the male threaded portion 31a. More specifically, the metal pipe 31 has a large-diameter portion 312 on the axial center side that has a larger outer diameter than the male threaded portion 31a and fits into the counterbore portion 321 described above, and the outer circumferential surface of this large-diameter portion 312 is the outward-facing surface 34.

[0054] The large-diameter portion 312 is formed on the axial side of the sealing member 15 of the metal pipe 31. In other words, the large-diameter portion 312 has a larger outer diameter than the portion on the outer circumferential surface of the metal pipe 31 where the male thread portion 31a and the sealing member 15 are provided, and in this case, it is the portion of the metal pipe 31 with the largest outer diameter. Specifically, the outer diameter of the large-diameter portion 312 is equal to the inner diameter of the counterbore portion 321, and as a result, the large-diameter portion 312 and the counterbore portion 321 are fitted together without play by a spigot structure. The outward-facing surface 34 is the outer circumferential surface of the portion of the large-diameter portion 312 that is fitted into the counterbore portion 321, or in other words, the portion on the outer circumferential surface of the large-diameter portion 312 that faces the inner circumferential surface of the counterbore portion 321. In other words, this outward-facing surface 34 is a different surface on the outer circumferential surface of the metal pipe 31 from the surface on which the male thread portion 31a and the sealing member 15 are provided, and in this case, it extends along the axial direction of the metal pipe 31 (substantially parallel to the axial direction).

[0055] Furthermore, as shown in Figures 2 and 3, the antenna 3 of this embodiment is equipped with a loosening suppression mechanism 5 that prevents the screw-fastened metal pipe 31 and insulating pipe 32 from loosening. However, the antenna 3 according to the present invention does not necessarily need to be equipped with the loosening suppression mechanism 5.

[0056] The loosening prevention mechanism 5 is constructed using an annular fastener 51 fitted onto the metal pipe 31. This annular fastener 51 is rotatable around the axis of the metal pipe 31 and slidable in the axial direction, and one or more protrusions 52 are provided on the end face facing the insulating pipe 32, projecting toward the insulating pipe 32. The number, shape, and arrangement of the protrusions 52 may be changed as appropriate.

[0057] On the other hand, a recess 53 is formed on the end face of the insulating pipe 32 facing the annular fastener 51, with the recess being cut out toward the axial center. Specifically, the recess 53 has a shape corresponding to the convex portion 52 and is formed at one or more positions corresponding to the convex portion 52.

[0058] These protrusions 52 and recesses 53 constitute the loosening suppression mechanism 5 described above, and the loosening of the metal pipe 31 and the insulating pipe 32 is suppressed when the protrusions 52 engage with the recesses 53.

[0059] In this configuration, the metal pipe 31 and the insulating pipe 32 are screw-fastened together. A second male threaded portion 31b is formed on the outer surface of the metal pipe 31, on the axial side of the insulating pipe 32. The loosening suppression mechanism 5 further includes a nut 54 that screws onto this second male threaded portion 31b. Specifically, this nut 54 has a larger outer diameter than the insulating pipe 32 and is positioned on the axial side of the annular fastener 51. With the convex portion 52 engaged with the concave portion 53, the nut 54 is rotated to move it axially outward, and the nut 54 presses the annular fastener 51 against the end face of the insulating pipe 32, thereby suppressing loosening of the metal pipe 31 and the insulating pipe 32.

[0060] <Effects of this embodiment> With the plasma processing apparatus 100 of this embodiment configured in this way, by making the male thread portion 31a and the female thread portion 32a multi-start threads, the number of threads engaged for the same engagement length is increased compared to a single-start triangular thread, so the load required to shear the contact portion of the male thread portion 31a and the female thread portion 32a is increased. Therefore, when fastening the metal pipe 31 and the insulating pipe 32, damage to the fastening portion of the metal pipe 31 and the insulating pipe 32 can be suppressed.

[0061] <Other modified embodiments> However, the present invention is not limited to the embodiments described above.

[0062] In the above embodiment, the male thread portion 31a and the female thread portion 32a were multi-thread triangular threads. However, if, in a cross-sectional view obtained by cutting the male thread portion 31a and the female thread portion 32a along the axial direction, the tops of the threads of the male thread portion 31a and the bottoms of the thread grooves of the female thread portion 32a are flat, then the male thread portion 31a and the female thread portion 32a may be single-thread threads. A single-thread thread, as shown in Figure 3, is a thread in which the distance L that the male thread portion 31a advances axially per revolution is equal to the distance P between adjacent tops of the male thread portion 31a. Specifically, as shown in Figure 3, the male thread portion 31a and the female thread portion 32a may be single-thread trapezoidal threads. In addition to single-thread trapezoidal threads, the male thread portion 31a and the female thread portion 32a may also be single-thread square threads or single-thread sawtooth threads, for example.

[0063] In the above embodiment, the male threaded portion 31a was formed on the outer circumferential surface of the metal pipe 31 and the female threaded portion 32a was formed on the inner circumferential surface of the insulating pipe 32. However, as shown in Figure 4, the male threaded portion 31a may be formed on the outer circumferential surface of the insulating pipe 32 and the female threaded portion 32a may be formed on the inner circumferential surface of the metal pipe 31. Specifically, the male threaded portion 31a is formed on the portion of the insulating pipe 32 that is inserted into the metal pipe 31, and the female threaded portion 32a is formed on the portion of the metal pipe 31 that surrounds the insulating pipe 32.

[0064] In this case, as shown in Figure 4, the antenna 3 further includes a conductive connecting member 36 that electrically connects the metal pipe 31 to the first electrode 33A or the second electrode 33B. Specifically, the male threaded portion 31a and the female threaded portion 32a are connected so that the metal pipe 31 and the insulating pipe 32 sandwich the conductive connecting member 36. A sealing member 15 is interposed between the insulating pipe 32 and the conductive connecting member 36.

[0065] Furthermore, although the antenna was straight in the above embodiment, it may also be curved or bent. In this case, the metal pipe may be curved or bent, or the insulating pipe may be curved or bent.

[0066] In addition, although the conductive and insulating elements were tubular in shape with one internal channel, they may have two or more internal channels, or branched internal channels. Furthermore, the conductive and / or insulating elements may be solid.

[0067] In the electrode of the above embodiment, the extension was cylindrical, but it may also be rectangular, flat, curved, or bent.

[0068] Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. [Explanation of symbols]

[0069] 100... Plasma processing equipment W ··· circuit board P ···Inductively coupled plasma 2...Vacuum container 3... Antenna 31 ···Metal pipe (conducting element) 32...Insulating pipe (insulating element) 32b...recess 33... Capacitor 33A...First electrode 33B...Second electrode 331...Flange section 332...extension part CL ···Coolant (liquid dielectric) 4...High frequency power supply

Claims

1. It is an antenna that generates plasma by allowing high-frequency current to flow. At least two tubular conductive elements, An insulating element having a cylindrical shape and provided between adjacent conductive elements to insulate those conductive elements, A capacitive element electrically connected in series with the aforementioned conductor elements adjacent to each other, A male screw portion formed on one of the conductor element and the insulating element, The conductor element and the other insulating element have a female screw portion formed on them. The male and female threaded portions are multi-start threads that connect the conductive element and the insulating element to each other, in an antenna.

2. The antenna according to claim 1, wherein in a cross-sectional view obtained by cutting the male thread portion and the female thread portion along the axial direction, the top of the thread of the male thread portion and the bottom of the thread groove of the female thread portion are flat.

3. The male screw portion is formed on the outer circumferential surface of the conductor element, The female thread portion is formed on the inner circumferential surface of the insulating element. The antenna according to claim 1, wherein the conductor element and the insulating element are connected by inserting the conductor element into the insulating element and screwing the male threaded portion and the female threaded portion together.

4. The antenna according to claim 1, wherein the insulating element is made of alumina, aluminum nitride, or machinable ceramics.

5. It is an antenna that generates plasma by allowing high-frequency current to flow. At least two tubular conductive elements, An insulating element having a cylindrical shape and provided between adjacent conductive elements to insulate those conductive elements, A capacitive element electrically connected in series with the aforementioned conductor elements adjacent to each other, A male screw portion formed on one of the conductor element and the insulating element, The conductor element and the other insulating element have a female screw portion formed on them. The male screw portion and the female screw portion connect the conductor element and the insulating element, An antenna in which, in a cross-sectional view obtained by cutting the male thread portion and the female thread portion along the axial direction, the top of the thread of the male thread portion and the bottom of the thread groove of the female thread portion are flat.

6. An antenna according to any one of claims 1 to 5, The aforementioned antenna is located inside or outside a vacuum vessel, A plasma processing apparatus comprising a high-frequency power supply for applying a high-frequency current to the antenna.

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