Plasma generator

Abstract

A radial gap is likely to form between the discharge tube and the cooler, which could lead to an unstable fixed state between the discharge tube and the cooler. [Solution] The cooler 30 of the plasma generator 20 has a disc-shaped flange 32 on which cooling tubes 84 are arranged, and a cylindrical sleeve 31 extending from the flange 32 toward the coil 24. At least one slit 33 is formed in the sleeve 31 in a direction along the central axis CL from the end 37 facing the coil 24. A gap S1 is formed between the discharge tube 22 and the cooler 30, and the cooler 30 is fixed to the discharge tube 22 with a non-conductive filler M(Ma) filling the gap S1. The slit 33 is further filled with filler M(Mb) in a manner continuous with the filler M(Ma) filling the gap S1.

Description

Technical Field

[0001] The present invention relates to a plasma generator.

Background Art

[0002] In a semiconductor manufacturing process, inductively coupled plasma (ICP) may be generated and various processes (such as cleaning) may be performed using the ICP. Patent Documents 1 and 2 describe plasma generators for generating ICP.

[0003] ICP is generated using a plasma generator in which a coil is wound around the outer periphery of a discharge tube. At this time, a high-frequency voltage is output from a high-frequency power source so that a high-frequency current flows through the coil, and a process gas (hereinafter referred to as gas) is introduced into the discharge tube. Then, the gas is ionized by an induced magnetic field caused by the high-frequency current flowing through the coil to generate plasma. In the initial stage, plasma called capacitively coupled plasma (CCP) is generated, and it is considered that ICP is generated in the stage of increasing the high-frequency current flowing through the coil.

[0004] When the gas inside the discharge tube is ionized to generate plasma, the electrons in the plasma obtained by ionization collide with the gas, and the gas decomposes. At this time, since the discharge tube is heated, for example, in Patent Document 2, a cooler into which the discharge tube is inserted is arranged on the downstream side of the discharge tube where the coil is arranged.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] However, due to the heat generated by the discharge tube during plasma generation, a radial gap is likely to form between the discharge tube and the cooler, which could lead to an unstable fixed state between the discharge tube and the cooler. The present invention has been made in view of the above, and provides a plasma generator that can stabilize the fixed state of the discharge tube and the cooler even when plasma is being generated. [Means for solving the problem]

[0007] In view of the above problems, the plasma generator according to the present invention is a plasma generator that introduces a gas into the interior and generates plasma inside, comprising: an insulating discharge tube having a cylindrical shape; a conductive coil wound around the outer circumference of the discharge tube with respect to the central axis of the discharge tube, and through which a high-frequency current of the RF band frequency flows in at least a portion of the winding; and a cooler inserted into the discharge tube along the axial direction of the discharge tube at a position adjacent to the coil downstream of the gas from the coil, and for cooling the discharge tube, wherein the cooler has a disc-shaped flange on which the cooler tube is arranged, and a cylindrical sleeve extending from the flange toward the coil, wherein at least one slit is formed in the sleeve from the end facing the coil in a direction along the central axis, a gap is formed between the discharge tube and the cooler, the cooler is fixed to the discharge tube with a non-conductive filler filling the gap, and the slit is further filled with a filler continuous with the filler filling the gap.

[0008] According to the present invention, the cooler can be fixed to the discharge tube with a non-conductive filler material filling the gap between the discharge tube and the cooler. The sleeve has at least one slit formed in the direction along the central axis from the end facing the coil, and the slit is further filled with filler material continuous with the filler material that fills the gap. As a result, there is a risk that eddy currents induced by the magnetic field formed by the coil will flow in the cooler, but since the slit provided in the sleeve is filled with a non-conductive filler material, the path of the current can be blocked and the flow of eddy currents can be prevented.

[0009] Furthermore, a non-conductive filler is placed in the gap between the discharge tube and the cooler, and the slit is further filled with filler, continuing from the filler placed in the gap. As a result, the filler placed in the slit acts as an anchor for fixing the discharge tube and the cooler together, thereby stabilizing the fixed state of the discharge tube and the cooler.

[0010] In a more preferred embodiment, the sleeve has a plurality of slits, which are formed at equal intervals in the circumferential direction of the sleeve. In this embodiment, since the plurality of slits formed at equal intervals in the circumferential direction of the sleeve are filled with filler material continuously with filler material that fills the gaps, the fixed state between the discharge tube and the cooler can be made more stable.

[0011] In a more preferred embodiment, at least one through-hole is formed near the flange of the sleeve, and the through-hole is further filled with filler material in a manner continuous with the filler material that fills the gap.

[0012] In this embodiment, since the filler material is further filled into the through-hole formed near the flange of the sleeve, in continuity with the filler material filling the gap, the circumferential fixing state of the cooler (sleeve) to the discharge tube can be stabilized. Furthermore, when filling the filler material, by confirming that the filler material reaches the through-hole when flowing the filler material between the discharge tube and the sleeve from the end of the sleeve facing the coil, it is possible to confirm that the filler material has been filled more uniformly between the discharge tube and the sleeve. [Effects of the Invention]

[0013] According to the plasma generator of the present invention, the fixed state between the discharge tube and the cooler can be stabilized. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows the configuration of the plasma generator according to the present invention. [Figure 2] Figure 1 is a perspective view of the plasma generator. [Figure 3] Figure 2 is a cross-sectional view along the central axis of the plasma generator shown. [Figure 4] (a) is a schematic perspective view of the cooler of the plasma generator shown in Figure 2, and (b) is a perspective view showing the cooler shown in Figure 2 inserted into the discharge tube. [Figure 5] (a) is a cross-sectional view along line AA in Figure 3, (b) is a cross-sectional view along line BB in Figure 5(a), and (c) is a cross-sectional view along line CC in Figure 5(a). [Figure 6] (a) and (b) are perspective views relating to modified versions of the cooler for the plasma generator shown in Figure 4(a). [Figure 7] (a) to (c) are perspective views relating to modified versions of the cooler for the plasma generator shown in Figure 4(a). [Figure 8] (a) and (b) are perspective views relating to modified versions of the cooler for the plasma generator shown in Figure 4(a). [Modes for carrying out the invention]

[0015] Referring to the attached drawings below, the plasma generating apparatus 10 equipped with the plasma generator 20 according to the embodiment will be described in detail. Note that the present invention is not limited by this embodiment.

[0016] 1. Overall Configuration of Plasma Generating Apparatus 10 and Plasma Generator 20 FIG. 1 is a diagram showing the configuration of the plasma generating apparatus 10 according to the embodiment. The plasma generating apparatus 10 according to the embodiment is a device that generates inductively coupled plasma (ICP). The plasma generating apparatus 10 according to the embodiment includes a high-frequency power supply 12, an impedance matching circuit 14, and a plasma generator 20.

[0017] The high-frequency power supply 12 outputs a high-frequency voltage with a frequency in the RF (Radio Frequency) band, and supplies high-frequency power to the plasma generator 20 via the impedance matching circuit 14. The impedance matching circuit 14 impedance-matches the high-frequency power output from the high-frequency power supply 12 and supplies it to the plasma generator 20.

[0018] The plasma generator 20 has gas introduced therein and generates plasma inside. The plasma generated by the plasma generator 20 is sent to, for example, a plasma processing chamber and used for various processes such as etching.

[0019] In this embodiment, the plasma generator 20 receives gas from the upper side in the figure and discharges plasma from the lower side in the figure. The upstream side of the gas flowing into the plasma generator 20 is defined as the upper side, and the downstream side of the gas flow is defined as the lower side. However, these upper and lower sides are specified for the sake of explanation, and the components and parts constituting the plasma generator 20 are not limited to these. In this embodiment, the plasma generator 20 has the upstream side of the flowing gas as the upper side and the downstream side as the lower side. However, for example, the plasma generator may be positioned by inverting the orientation of the plasma generator 20 shown in Figure 1 so that the upstream side of the flowing gas is the lower side and the downstream side is the upper side. Alternatively, the plasma generator 20 shown in Figure 1 may be placed horizontally so that the upstream and downstream sides of the gas flow are aligned horizontally. In this way, the orientation in which the plasma generator 20 is positioned is not particularly limited, as long as the effects described later can be achieved by the plasma generator 20.

[0020] The overall structure of the plasma generator 20 according to this embodiment will be described below with reference to Figures 2 and 3. Figure 2 is a perspective view of the plasma generator shown in Figure 1. Figure 3 is a cross-sectional view of the plasma generator shown in Figure 2 along its central axis.

[0021] As shown in Figures 2 and 3, the plasma generator 20 comprises at least a covering 26A, a discharge tube 22, a coil 24, a cooler 30, and a connecting tube 70. The discharge tube 22 is cylindrical and made of an insulating material such as quartz or alumina. The covering 26A is attached to one end of the discharge tube 22, and the connecting tube 70 is attached to the other end. A gas introduction hole 28 is formed in the covering 26A. Between the covering 26A and the connecting tube 70, the coil 24 and the cooler 30 are attached to the discharge tube 22.

[0022] The coil 24 is made of a conductive material such as a copper alloy and is wound around the outer circumference of the discharge tube 22, with the central axis CL of the discharge tube 22 as the center axis. High-frequency power is supplied to the coil 24 from the high-frequency power supply 12 via the impedance matching circuit 14. Specifically, the coil 24 is configured so that a high-frequency current with a frequency in the RF band flows through at least a portion of the winding.

[0023] In this type of plasma generator 20, the inside of the discharge tube 22 is kept in a high vacuum state, and gas is introduced into the interior through the gas introduction hole 28 of the covering 26A. The plasma generator 20 ionizes the gas inside the discharge tube 22 and turns it into plasma through inductive coupling with a fluctuating magnetic field generated by a high-frequency current in the RF band flowing through the coil 24, thereby generating inductively coupled plasma (ICP). The generated plasma is sent to a plasma processing chamber or the like through the gas discharge hole of the connecting cylinder 70, which will be described later, via the opening on the opposite side of the gas introduction hole 28 in the discharge tube 22 (the other opening 22c).

[0024] When the gas inside the discharge tube 22 is ionized and plasma is generated, the gas decomposes. For example, if the gas is NF3 (nitrogen trifluoride), it will decompose into N (nitrogen) and 3F (fluorine). The decomposed N (nitrogen) and 3F (fluorine) are sent to a plasma processing chamber (not shown) downstream of the plasma generator 20, where cleaning and other processes are performed. For example, when cleaning is performed, gaseous SiF4 is generated by a chemical reaction between the Si film remaining in the plasma processing chamber and F (fluorine), and the Si film can be removed by discharging these gases with a vacuum pump.

[0025] Of course, the application of the plasma generator 20 of this embodiment is not limited to cleaning within a plasma processing chamber as described above. For example, it can be applied to the detoxification of harmful gases. When applied to the detoxification of harmful gases, the harmful gas flowing from upstream is ionized and converted into plasma. In this process, the harmful gas is decomposed and rendered harmless. Furthermore, the gas used is not limited to NF3, and various gases can be used depending on the application (cleaning, detoxification, etc.). For example, O2 can be used. Details of each component are described below.

[0026] 2. Regarding the coating 26A As shown in Figures 2 and 3, the covering 26A is a cover member that covers one opening 22b of the discharge tube 22 and is made of a metal material such as aluminum. The covering 26A has a gas introduction hole 28 formed at a position corresponding to the central axis CL of the discharge tube 22 for introducing gas into the inside of the discharge tube 22. The covering 26A has a connecting cylinder 44 and a lid 26. In this embodiment, the covering 26A is composed of a connecting cylinder 44 and a lid 26, but the covering 26A may be composed of only a lid 26 as long as the lid 26 can be positioned to cover one opening 22b of the discharge tube 22 with the lid 26.

[0027] The connecting cylinder 44 is cylindrical and made of a metal material such as aluminum. It is fitted onto one opening 22b of the discharge tube 22 and connected to the discharge tube 22 via an upper flange 42. The central axis CL of the discharge tube 22 and the (cylindrical) axis of the connecting cylinder 44 coincide. The connecting cylinder 44 is substantially cylindrical in shape, with its inner circumference matching the outer circumference of the discharge tube 22, and the discharge tube 22 is inserted inside it. A flange portion 46 is formed on the connecting cylinder 44 at a position opposite the upper flange 42. At the upper position of the connecting cylinder 44, a flange portion 48 is formed which is connected to a gas supply source (not shown).

[0028] A groove is formed on the inside (discharge tube 22 side) of the lower end of the connecting cylinder 44, and an O-ring 49 is inserted into it. By fixing the flange portion 46 and the upper flange 42 with bolts or the like, the O-ring 49 is sandwiched between the flange portion 46 and the upper flange 42. As a result, the O-ring 49 deforms, sealing the gap between the discharge tube 22 and the flange portion 46, and maintaining airtightness above the discharge tube 22.

[0029] The cover 26 is disc-shaped and is positioned to cover the opening 44a formed in the connecting cylinder 44. The cover 26 is fixed to the connecting cylinder 44 while resting on a flange portion 48 formed on the connecting cylinder 44. This allows the cover 26 to close one of the openings 22b of the discharge tube 22. When the connecting cylinder 44 is connected to the discharge tube 22, the cover 26 is positioned at a distance from the end face 22e of the opening 22b of the discharge tube 22 in the direction along the central axis CL of the discharge tube 22. The cover 26 and the flange portion 48 may be integrally formed. Doing so can reduce costs.

[0030] 3. About Coil 24 The coil 24 of the plasma generator 20 is located in the central region of the discharge tube 22 in the direction of the central axis CL. The outer cross-sectional shape of the coil 24 is rectangular, for example, square. The coil 24 is a linear conductor and is wound around the outer circumference of the discharge tube 22 at a predetermined pitch and for a predetermined number of turns, centered on the central axis CL of the discharge tube 22. As a result, the coil 24 is wound around the outer circumference of the discharge tube 22, centered on the central axis CL of the discharge tube 22.

[0031] The coil 24 is hollow inside, and a cooling channel 52 through which a refrigerant flows is formed inside. The coil 24 is provided with a first connection part 54 at one end and a second connection part 56 at the other end. One of the first connection part 54 and the second connection part 56 is a connection jig for introducing the refrigerant into the cooling channel 52 inside the coil 24, and the other is a connection jig for discharging the refrigerant from the cooling channel 52 of the coil 24. As a result, the cooling channel 52 inside the coil 24 can circulate the refrigerant from one end to the other, cooling the coil 24 and the discharge tube 22. By including such a cooling channel 52, the coil 24 can efficiently cool the heat generated by the coil 24.

[0032] The coil 24 has at least a winding portion 24a that is energized. The winding portion 24a is provided in the middle of the coil 24, from one end to the other, and a first electrode 62 and a second electrode 64 are provided at both ends of the winding portion 24a. High-frequency power is supplied to the first electrode 62 and the second electrode 64 from the impedance matching circuit 14. As a result, a current corresponding to the high-frequency power flows between the first electrode 62 and the second electrode 64, and the coil 24 can generate a high-frequency magnetic field. Alternatively, the first and second electrodes 62 and 64 may be provided from one end to the other of the coil 24, and the entire coil 24 may be energized.

[0033] 4. Regarding the structure of the discharge tube 22 and its connection As described above, the discharge tube 22 of the plasma generator 20 has a cylindrical shape, and the gas that will become the plasma material passes through the inside of the discharge tube 22. A disc-shaped upper flange 42 is attached to the discharge tube 22 in an externally fitted state. The upper flange 42 is made of a metal material such as aluminum and is externally fitted to the discharge tube 22 in the area between the region where the coil 24 is wound and the opening 22b on one side of the outer surface of the discharge tube 22 along the central axis CL. The upper flange 42 may also be fitted into the discharge tube 22.

[0034] As shown in Figures 2 and 3, the discharge tube 22 is inserted into the cooler 30 along the axial direction of the discharge tube 22, at a position adjacent to the coil 24, downstream of the coil 24. Furthermore, as shown in Figures 2 and 3, a disc-shaped connecting plate 89 and a connecting cylinder 70 are attached to the discharge tube 22 in an externally fitted state. The connecting plate 89 is made of a metal material such as aluminum. The connecting plate 89 has an insertion hole through which the discharge tube 22 is inserted. The connecting plate 89 is externally fitted to the discharge tube 22 in the area of ​​the outer circumferential surface of the discharge tube 22 along the central axis CL, between the region where the coil 24 is wound and the opening 22c on the other side.

[0035] On the surface of the connecting plate 89 facing the cooler 30, a groove is formed along the periphery of the through hole, into which an O-ring 92 is inserted. By fixing the flange 32 of the cooler 30 and the connecting plate 89 with bolts or the like, the O-ring 92 is sandwiched between the cooler 30 and the connecting plate 89. As a result, the O-ring 92 deforms, sealing the gap between the discharge tube 22 and the cooler 30, and maintaining airtightness below the discharge tube 22.

[0036] As shown in Figure 3, a connecting cylinder 70 is attached to the discharge tube 22 in an externally fitted state. The connecting cylinder 70 is made of a metal such as aluminum and is attached to a position that includes the lower end of the discharge tube 22. The connecting cylinder 70 has a cylindrical tube portion 74. The inner circumference of the tube portion 74 matches the outer circumference of the discharge tube 22, and the discharge tube 22 is inserted into the inside. A flange portion 76 is formed on the connecting cylinder 70 at a position opposite to the connecting plate 89, and the connecting plate 89 and the flange portion 76 are fixed in contact with each other by fasteners 77 or the like. Seals 93 and 94 are disposed between the connecting plate 89 and the flange portion 76. A lower flange portion 78 is formed on the connecting cylinder 70 at its lower position.

[0037] 5. Structure of the cooler 30 and packing material M The structure of the cooler 30 and the packing material M will be described below, with reference to Figures 2, 4, and 5. Figure 4(a) is a schematic perspective view of the cooler of the plasma generator shown in Figure 2, and Figure 4(b) is a perspective view showing the cooler shown in Figure 2 inserted into the discharge tube. Figure 5(a) is a cross-sectional view along line AA in Figure 3, Figure 5(b) is a cross-sectional view along line BB in Figure 5(a), and (c) is a cross-sectional view along line CC in Figure 5(a).

[0038] The cooler 30 cools the discharge tube 22. As shown in Figures 2 and 4(a), the cooler 30 has a disc-shaped flange 32 on which the cooling tube 84 is arranged, and a cylindrical sleeve 31 extending from the flange 32 toward the coil 24. The flange 32 has an insertion hole for inserting the discharge tube 22 and a groove 39 for accommodating a portion of the cooling tube 84, formed along the circumferential direction of the flange 32. The cooler 30 is made of a metal material such as aluminum and is positioned between the coil 24 and the connecting plate 89. The connecting plate 89 may be fitted onto the discharge tube 22. An insertion hole 36 for inserting a temperature measuring sensor (e.g., a thermocouple) is formed on the circumferential surface of the flange 32.

[0039] Thus, the cooling tube 84 is housed in the groove 39 of the flange 32, and is formed to circumfer the discharge tube 22 along the circumferential direction of the flange 32 of the cooler 30. As shown in Figure 2, the cooling tube 84 is provided with a third connection part 86 at one end and a fourth connection part 88 at the other end. One of the third connection part 86 and the fourth connection part 88 is a connection jig for introducing refrigerant into the cooling tube 84, and the other is a connection jig for discharging refrigerant from the cooling tube 84. This allows the discharge tube 22 to be cooled by the cooling tube 84.

[0040] As shown in Figure 4(a), the end portion 37 of the sleeve 31 has steps 38A and 38B formed at equal intervals along the circumferential direction. Specifically, the end portion 37 has a stepped shape in which the height of the end portion 37 increases at regular intervals by steps 38B, counterclockwise from the lowest position, according to the shape of the helical winding of the coil 24 facing the axial direction. Steps 38A are formed at the highest position due to step 38B and at the lowest position.

[0041] In this embodiment, the sleeve 31 has multiple (e.g., five) slits 33 formed in the direction along the central axis CL from the end 37 facing the coil 24. In this embodiment, the slits 33 are formed at equal intervals along the circumferential direction and extend toward the flange 32 from the positions where steps 38A and 38B are formed. Multiple (e.g., five) through holes 34 are formed in the sleeve 31 near the flange 32.

[0042] A gap S1 (see Figure 4(b)) is formed between the discharge tube 22 and the cooler 30. The gap S1 is filled with a non-conductive filler material M (Ma). With the filler material Ma filled (see Figures 5(a) to 5(c), etc.), the cooler 30 is fixed to the discharge tube 22. As shown in Figures 5(a) and 5(b), the slit 33 is further filled with filler material Mb, continuous with the filler material Ma that is filled in the gap S1. Furthermore, as shown in Figures 5(a) and 5(c), the through hole 34 is further filled with filler material Mc, continuous with the filler material Ma that is filled in the gap S1.

[0043] The material of these fillers M is not particularly limited as long as it is insulating (non-conductive), and it is especially preferable that it is a heat-resistant material with a low high-frequency dielectric loss tangent and elasticity. Examples of fillers M include rubber, and thermosetting silicone rubber is one example.

[0044] According to this embodiment, the cooler 30 can be fixed to the discharge tube 22 with a non-conductive filler material Ma filling the gap S1 between the discharge tube 22 and the cooler 30. In addition, a slit 33 is formed in the sleeve 31 of the cooler 30, extending from the end facing the coil in a direction along the central axis CL. The slit 33 is further filled with a filler material Mb. The filler material Mb filled in the slit 33 is continuous with the filler material Ma filled in the gap S1. That is, the filler material Ma and the filler material Mb are integrally formed. As a result, there is a risk that eddy currents induced by the magnetic field formed by the coil 24 may flow in the cooler 30, but since the slit 33 provided in the sleeve 31 is filled with a non-conductive filler material M(Mb), the current path can be blocked and the flow of eddy currents can be suppressed.

[0045] Furthermore, the slit 33 is further filled with filler material Mb, continuous with the filler material Ma that fills the gap S1. As a result, the filler material M that fills the slit 33 contributes as an anchoring effect for fixing the discharge tube 22 and the cooler 30, thereby stabilizing the fixed state of the discharge tube 22 and the cooler 30. In particular, by using rubber as the filler material M, the filler material M follows the difference in thermal expansion between the cooler 30 and the discharge tube 22 in response to the heat generated during plasma generation, thereby reducing the occurrence of these gaps.

[0046] Furthermore, since the filler material Mb is filled into the multiple slits 33 formed at equal intervals in the circumferential direction of the sleeve 31, in addition to the filler material Ma filled into the gap S1, the fixing state between the discharge tube 22 and the cooler 30 can be made more stable. In addition, the through hole 34 formed in the sleeve 31 near the flange 32 is also filled with filler material Mc, in addition to the filler material Ma filled into the gap S1. That is, in addition to the filler material Ma and filler material Mb being formed integrally, the filler material Ma and filler material Mc are also formed integrally. As a result, the circumferential fixing state of the cooler 30 (sleeve 31) to the discharge tube 22 can be made stable.

[0047] Here, when filling with the filler material M, first the outer surface 31b of the sleeve 31 is covered with a resin tape or the like to cover the slit 33 and the through hole 34. In this state, the filler material M is poured between the discharge tube 22 and the sleeve 31 from the end 37 of the sleeve 31 facing the coil. This ensures that the filler material M fills the slit 33 and reaches the through hole 34, thereby confirming that the filler material M is filled more uniformly between the discharge tube 22 and the sleeve 31.

[0048] In this configuration, the plasma generator 20 receives a gas, which will be the material for the plasma, from a gas inlet 28, and is supplied with high-frequency power to the coil 24. First, the plasma generator 20 uses the voltage of the coil 24 to ionize the gas inside the discharge tube 22, which is under vacuum, thereby generating capacitively coupled plasma (CCP). Then, as the current flowing through the coil 24 increases, the plasma generator 20 generates an induced magnetic field, generating inductively coupled plasma PR (see Figure 3). At this time, the discharge tube 22 is heated by the current flowing through the coil 24, and a difference in thermal expansion occurs between the discharge tube 22 and the cooler 30. However, as shown in the effects described above, the coil 24 and the cooler 30 can be stably held in the discharge tube 22.

[0049] Figures 6(a) and 6(b) show modified versions of the cooler 30 shown in Figure 4(a). In Figure 4(a), slits 33 are formed in the steps 38A and 38B, but as shown in Figure 6(a), slits 33 may be formed at equal intervals between these steps 38A and 38B. Also, in the cooler 30 of Figure 6(a), multiple (five) slits 33 are provided, but as shown in Figure 6(b), one slit 33 may be provided at the end 37 of the sleeve 31, which is the highest point from the flange 32.

[0050] Furthermore, Figures 7(a) to 7(c) show modified versions of the cooler 30 shown in Figure 4(a). In this example, the sleeve 31 does not have a through hole 34, but instead has multiple (e.g., 10) slits 33. In Figure 7(a), slits 33 are formed at the positions of all the steps 38A and 38B shown in Figure 4(a). In Figure 7(b), slits 33 are formed between all adjacent steps 38A and 38B in the circumferential direction, as shown in Figure 4(a). Furthermore, in Figure 7(c), similar to Figure 6(b), one slit 33 is provided at the highest end 37 of the sleeve 31 from the flange 32, and the other slits 33a extend from the end 37 to the same height H from the flange 32. By making the length of the slits 33a of the cooler 30 shown in Figure 7(c) shorter than that shown in Figure 7(b), the heat transfer from the sleeve 31 to the flange 32 can be increased.

[0051] Furthermore, Figures 8(a) and 8(b) show modified versions of the cooler 30 shown in Figure 4(a). In this example, the end 37 of the sleeve 31 has no steps and has a continuous ring-shaped end face. In Figure 8(a), one slit 33 and multiple through holes 34 are formed, while in Figure 8(b), multiple (e.g., three) slits 33 and multiple (e.g., six) through holes 34 are formed. Even with such a structure, the same effects as described above can be expected from the slits 33 and through holes 34.

[0052] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims. [Explanation of Symbols]

[0053] 20: Plasma generator, 22: Discharge tube, 24: Coil, 30: Cooler, 31: Sleeve, 32: Flange, 33: Slit, 34: Through hole, 84: Cooling tube, M, Ma~Mf: Filler

Claims

1. A plasma generator that introduces a gas into its interior and generates plasma inside, A cylindrical insulating discharge tube, A conductive coil is wound around the outer circumference of the discharge tube, with the central axis of the discharge tube as the center axis, and at least a portion of the winding is through which a high-frequency current of the RF band frequency flows. Downstream of the coil, adjacent to the coil, the discharge tube is inserted along the axial direction of the discharge tube, and a cooler is provided to cool the discharge tube. Equipped with, The cooler has a disc-shaped flange on which the cooling tubes are arranged, and a cylindrical sleeve extending from the flange toward the coil. The sleeve has at least one slit formed in the direction along the central axis, extending from the end facing the coil. A gap is formed between the discharge tube and the cooler, and the cooler is fixed to the discharge tube with a non-conductive filler material filling the gap. A plasma generator characterized in that the slit is further filled with a filler material, continuous with the filler material that has been filled into the gap.

2. The plasma generator according to claim 1, characterized in that the sleeve has a plurality of slits formed thereon, and the plurality of slits are formed at equal intervals in the circumferential direction of the sleeve.

3. At least one through hole is formed in the sleeve near the flange, The plasma generator according to claim 1, characterized in that the through hole is further filled with a filler material in a manner continuous with the filler material that has been filled into the gap.

Images