Inductive coil structure and inductively coupled plasma generator

Abstract

To provide an inductively coupled plasma generator, in which capacitive coupling is reduced by the structure of an inductive coil and improved stability and efficiency can be achieved.SOLUTION: An inductively coupled plasma generator 100 includes: a dielectric tube 130 extending in a length direction; a first inductive coil structure 110, which is provided to enclose the dielectric tube 130 and produces inductively-coupled plasma in the dielectric tube 130; an RF power supply 140, which is configured to provide positive and negative powers having opposite phases, to respectively supply positive and negative powers of RF power 140 to both ends of the first inductive coil structure 110, and to change a driving frequency; a first main capacitor 121 provided between a positive output terminal of the RF power supply 140 and one end of the first inductive coil structure 110; and a second main capacitor 122 provided between a negative output terminal of the RF power supply 140 and the other end of the first inductive coil structure 110.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] The present invention relates to an inductively coupled plasma generating device, and more particularly to an inductively coupled plasma generating device having a voltage distribution structure by inserting a capacitor between a plurality of antennas.

Background Art

[0002] Plasma is conventionally used in an etching process or a deposition process of a substrate such as a semiconductor wafer. Also, plasma is used in new material synthesis, surface treatment, environmental purification, etc. On the other hand, atmospheric pressure plasma is used in a plasma scrubber, cleaning, sterilization, skin beautification, etc.

[0003] A normal inductively coupled plasma is used by winding an induction coil around a dielectric discharge tube. However, a normal induction coil structure has low discharge stability and low plasma density.

[0004] The present invention provides a new induction coil structure capable of stably generating inductively coupled plasma at atmospheric pressure or a high pressure of several torr or more.

Summary of the Invention

Problems to be Solved by the Invention

[0005] One technical problem to be solved by the present invention is to provide an induction coil for generating inductively coupled plasma that suppresses a charge coupling component and improves discharge stability and efficiency.

[0006] One technical problem to be solved by the present invention is to provide an induction coil and a plasma generating device that suppress an increase in voltage due to an increase in the number of turns of the induction coil.

[0007] One technical problem to be solved by the present invention is to provide an induction coil that maximizes the number of turns per unit length and suppresses charge coupling.

Means for Solving the Problems

[0008] According to an embodiment of the present invention, an inductively coupled plasma generating apparatus includes a dielectric tube extending in a length direction, a first inductive coil structure disposed to surround the dielectric tube and generate inductively coupled plasma in the dielectric tube, an RF power supply that provides a positive output and a negative output with opposite phases, supplies the positive output and the negative output of RF power to both ends of the first inductive coil structure respectively, and changes a driving frequency, a first main capacitor disposed between the positive output terminal of the RF power supply and one end of the first inductive coil structure, and a second main capacitor disposed between the negative output terminal of the RF power supply and the other end of the first inductive coil structure. The first inductive coil structure includes inductive coils that are connected in series with each other, disposed in different layers respectively, and each layer has at least one turn or more, and auxiliary capacitors disposed between adjacent inductive coils respectively to distribute the voltage applied to the inductive coils.

[0009] In an embodiment of the present invention, each of the inductive coils has the same first inductance L1, each of the auxiliary capacitors has the same first capacitance C1, and the driving frequency of the RF power supply is controlled to match the resonance frequency by the series-connected first inductance L1 and the first capacitance C1.

[0010] In an embodiment of the present invention, the first main capacitor and the second main capacitor each have the same second capacitance C2, and the second capacitance C2 is twice the first capacitance C1.

[0011] In an embodiment of the present invention, each of the inductive coils is a 2-turn to 4-turn antenna.

[0012] In one embodiment of the present invention, a second induction coil structure is further included which is arranged to surround the dielectric tube, is spaced apart from the first induction coil structure, has the same structure as the first induction coil structure, and generates inductively coupled plasma in the dielectric tube. One end of the second induction coil structure is connected to one end of the first induction coil structure, the other end of the second induction coil structure is connected to the other end of the first induction coil structure, and the first induction coil structure and the second induction coil structure are connected in parallel with each other between the first main capacitor and the second main capacitor.

[0013] In one embodiment of the present invention, each of the induction coils constituting the first induction coil structure and the second induction coil structure has the same first inductance L1, each of the auxiliary capacitors constituting the first induction coil structure and the second induction coil structure has the same first capacitance C1, and the driving frequency of the RF power supply is controlled to match the resonance frequency of the series-connected first inductance L1 and the first capacitance C1.

[0014] In one embodiment of the present invention, the first main capacitor and the second main capacitor each have the same second capacitance C2, and the second capacitance C2 is four times the first capacitance C1.

[0015] In one embodiment of the present invention, one end of the first induction coil structure and one end of the second induction coil structure are arranged adjacent to each other, and one end of the first induction coil structure and one end of the second induction coil structure are connected to each other and connected to the first main capacitor.

[0016] In one embodiment of the present invention, each of the induction coils has a portion open in a first direction in a rectangular coordinate system, has a first central angle, is disposed in a placement plane, and has a first arc portion having a constant first radius; a second arc portion having a second central angle not exceeding the first central angle, disposed in the placement plane, having a second radius larger than the first radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a first connecting portion disposed in the placement plane, connected to one end of the first arc portion, and extending in the first direction; a "U"-shaped first arc connecting portion disposed in the placement plane, connecting the other end of the first arc portion and one end of the second arc portion; and a second connecting portion disposed in the placement plane, connected to the other end of the second arc portion, and extending in the first direction.

[0017] In one embodiment of the present invention, each of the induction coils has a portion open in a first direction in a rectangular coordinate system, has a first central angle, is disposed in a placement plane, and has a first arc portion having a constant first radius; a second arc portion having a second central angle not exceeding the first central angle, disposed in the placement plane, having a second radius larger than the first radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a third arc portion having a third central angle not exceeding the second central angle, disposed in the placement plane, having a third radius larger than the second radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a first connecting portion disposed in the placement plane, connected to one end of the first arc portion, and extending in the first direction; a "U"-shaped first arc connecting portion disposed in the placement plane, connecting the other end of the first arc portion and one end of the second arc portion; a "U"-shaped second arc connecting portion disposed in the placement plane, connecting the other end of the second arc portion and one end of the third arc portion; and a second connecting portion disposed in the placement plane, connected to the other end of the third arc portion, and extending in the first direction.

[0018] In one embodiment of the present invention, each of the induction coils has a portion open in the first direction in a rectangular coordinate system, has a first central angle, is disposed in a disposed plane, and has a first arc portion having a constant first radius; a second arc portion having a second central angle not greater than the first central angle, disposed in the disposed plane, having a second radius greater than the first radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a third arc portion having a third central angle not greater than the second central angle, disposed in the disposed plane, having a third radius greater than the second radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a fourth arc portion having a fourth central angle not greater than the third central angle, disposed in the disposed plane, having a fourth radius greater than the third radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a first connecting portion disposed in the disposed plane, connected to one end of the first arc portion, and extending in the first direction; a first arc connecting portion in a "U" shape disposed in the disposed plane, connecting the other end of the first arc portion and one end of the second arc portion; a second arc connecting portion in a "U" shape disposed in the disposed plane, connecting the other end of the second arc portion and one end of the third arc portion; a third arc connecting portion in a "U" shape disposed in the disposed plane, connecting the other end of the third arc portion and one end of the fourth arc portion; and a second connecting portion disposed in the disposed plane, connected to the other end of the fourth arc portion, and extending in the first direction.

[0019] In one embodiment of the present invention, the first induction coil structure and the second induction coil structure are arranged to be mirror-symmetrical up / down with respect to a point of the dielectric discharge tube, and the current is dispersed from the center up / down and then gathered again at both ends.

[0020] In one embodiment of the present invention, the power input ends of the induction coils are arranged to maintain a constant angle in the azimuth direction with respect to each other.

[0021] In one embodiment of the present invention, at least a part of the induction coils is fixed by a ceramic mold.

[0022] In one embodiment of the present invention, an insulating spacer in the form of a washer disposed between the induction coils and electrically insulating is further included.

[0023] In one embodiment of the present invention, the induction coil includes a first induction coil and a fourth induction coil stacked in order, the auxiliary capacitor includes a first to a third auxiliary capacitor, and when the first induction coil is disposed, the second induction coil is rotated counterclockwise by 90 degrees and aligned and disposed below the first induction coil. When the second induction coil is disposed, the third induction coil is rotated counterclockwise by 90 degrees and aligned and disposed below the second induction coil. When the third induction coil is disposed, the fourth induction coil is rotated counterclockwise by 90 degrees and aligned and disposed below the third induction coil. One end of the first induction coil is connected to the positive output end of the RF power supply through the first main capacitor, the other end of the first induction coil is connected to one end of the second induction coil through the first auxiliary capacitor, the other end of the second induction coil is connected to one end of the third induction coil through the second auxiliary capacitor, the other end of the third induction coil is connected to one end of the fourth induction coil through the third auxiliary capacitor, and the other end of the fourth induction coil is connected to the negative output end of the RF power supply through the second main capacitor.

[0024] A substrate processing apparatus according to an embodiment of the present invention includes a process chamber for processing a semiconductor substrate, and an inductively coupled plasma generator for providing active species by plasma to the process chamber. The inductively coupled plasma generator includes a dielectric tube extending in a length direction, a first induction coil structure disposed so as to surround the dielectric tube and generating inductively coupled plasma in the dielectric tube, an RF power supply providing positive and negative outputs having opposite phases to each other, supplying the positive and negative outputs of RF power to both ends of the first induction coil structure respectively, and changing a driving frequency, a first main capacitor disposed between the positive output terminal of the RF power supply and one end of the first induction coil structure, and a second main capacitor disposed between the negative output terminal of the RF power supply and the other end of the first induction coil structure. The first induction coil structure includes induction coils connected in series with each other, disposed in different layers respectively, each layer having at least one turn or more, and auxiliary capacitors disposed between adjacent induction coils respectively for distributing the voltage applied to the induction coils.

[0025] An induction coil structure according to an embodiment of the present invention is disposed so as to surround a dielectric tube and generates inductively coupled plasma in the dielectric tube. The induction coil structure includes induction coils connected in series with each other, disposed in different layers respectively, each layer having at least one turn or more and having the same structure, and auxiliary capacitors disposed between adjacent induction coils respectively for distributing the voltage applied to the induction coils.

[0026] In one embodiment of the present invention, each of the induction coils has a portion open in the first direction in a rectangular coordinate system, has a first central angle, is disposed in a placement plane, and has a first arc portion having a constant first radius; a second arc portion having a second central angle equal to or less than the first central angle, disposed in the placement plane, having a second radius larger than the first radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a third arc portion having a third central angle equal to or less than the second central angle, disposed in the placement plane, having a third radius larger than the second radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a first connecting portion disposed in the placement plane, connected to one end of the first arc portion, and extending in the first direction; a first arc connecting portion in a "U" shape disposed in the placement plane, connecting the other end of the first arc portion and one end of the second arc portion; a second arc connecting portion in a "U" shape disposed in the placement plane, connecting the other end of the second arc portion and one end of the third arc portion; and a second connecting portion disposed in the placement plane, connected to the other end of the third arc portion, and extending in the first direction.

[0027] In one embodiment of the present invention, each of the induction coils has a portion open in the first direction in a rectangular coordinate system, has a first central angle, is disposed in an arrangement plane, and has a first arc portion having a constant first radius; a second arc portion having a second central angle equal to or less than the first central angle, disposed in the arrangement plane, having a second radius larger than the first radius, and arranged to have the same central axis as the central axis of the first arc portion; a third arc portion having a third central angle equal to or less than the second central angle, disposed in the arrangement plane, having a third radius larger than the second radius, and arranged to have the same central axis as the central axis of the first arc portion; a fourth arc portion having a fourth central angle equal to or less than the third central angle, disposed in the arrangement plane, having a fourth radius larger than the third radius, and arranged to have the same central axis as the central axis of the first arc portion; a first connecting portion disposed in the arrangement plane, connected to one end of the first arc portion, and extending in the first direction; a first arc connecting portion in a "U" shape disposed in the arrangement plane, connecting the other end of the first arc portion and one end of the second arc portion; a second arc connecting portion in a "U" shape disposed in the arrangement plane, connecting the other end of the second arc portion and one end of the third arc portion; a third arc connecting portion in a "U" shape disposed in the arrangement plane, connecting the other end of the third arc portion and one end of the fourth arc portion; and a second connecting portion disposed in the arrangement plane, connected to the other end of the fourth arc portion, and extending in the first direction.

Effects of the Invention

[0028] The plasma generating device according to one embodiment of the present invention reduces capacitive coupling due to the structure of the induction coil and stably provides highly efficient inductive coupling plasma.

[0029] The plasma generating device according to one embodiment of the present invention distributes voltage through an auxiliary capacitor connected in series between the induction coils constituting the induction coil structure, thereby reducing the maximum voltage applied overall.

[0030] According to an embodiment of the invention, a plasma generating device suppresses the generation of parasitic capacitors, improves discharge stability, and suppresses local ion sputtering as the individual induction coils constituting the induction coil structure have the same potential at the points where they contact the dielectric tube.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5A

Figure 5B

Embodiments for Carrying Out the Invention

[0032] An antenna arranged to surround a dielectric discharge tube, and a high potential (3 kV or more) is applied under conditions of low pressure (a pressure range without a fluid effect of several tens of Torr or less) in the dielectric discharge tube. In this case, plasma is generated in the dielectric discharge tube. The surface of the dielectric discharge tube is heated by ion collisions. As a result, the dielectric discharge tube is heated to 1000 degrees Celsius or more. The high heat modifies the surface of the dielectric discharge tube or generates perforations in the dielectric discharge tube.

[0033] The high potential applied to the antenna is affected by the inductance, frequency, and current of the antenna. Under high power conditions, the high potential applied to the antenna always appears. Therefore, it is necessary to lower the high potential generated in the antenna.

[0034] The present invention proposes a method capable of reducing the applied high voltage and minimizing heating by ion collisions when such high power of several kilowatts or more is applied.

[0035] The inductively coupled plasma device is used in a semiconductor process device, an inductively coupled spectroscopic analyzer, an ion beam generator, a cleaning device in a deposition chamber, an exhaust port cleaning device of a deposition chamber, a plasma scrubber for removing waste gas from a semiconductor process device, a cleaning device for cleaning a process chamber of a chemical vapor deposition device, and the like.

[0036] According to an embodiment of the present invention, the inductively coupled plasma generating device is used as a remote plasma source for providing active species to a semiconductor process chamber.

[0037] The induction coil that generates inductively coupled plasma and the plasma are modeled by a transformer circuit. As a result, inductively coupled plasma is called transformer coupled plasma. The induction coil operates by the primary coil of the transformer circuit, and the plasma operates by the secondary coil of the transformer circuit. A magnetic flux confinement substance such as a magnetic material is used to increase the magnetic coupling between the induction coil and the plasma. However, it is difficult to apply the magnetic flux confinement substance to a dielectric discharge vessel having a cylindrical structure. Another method of increasing the magnetic coupling on the induction coil and the plasma is to increase the inductance or the number of turns of the induction coil. However, an increase in the inductance of the induction coil increases the impedance and makes efficient power transmission difficult. Also, an increase in the inductance of the induction coil increases the voltage applied to the induction coil and induces parasitic arc discharge. Also, the high voltage applied to the induction coil induces capacitive coupling discharge and induces damage due to ion bombardment and thermal damage to the dielectric discharge vessel.

[0038] According to an embodiment of the present invention, in order to reduce the voltage applied to the induction coil, a capacitor is disposed between the induction coils connected in series, and accordingly the total voltage is divided between the induction coil and the capacitor. Specifically, the induction coil is divided, an auxiliary capacitor is disposed between the divided induction coils, and main capacitors are respectively disposed at both ends of the induction coil. As a result, the electrostatic field due to the screening effect is reduced, and the voltage applied to the induction coil is reduced by the voltage division model. The divided induction coil and the auxiliary capacitor constitute a series resonance circuit, and the resonance frequency of the resonance circuit is the same as the driving frequency of the AC power supply. As a result, stable impedance matching is performed while a low voltage is applied to the induction coil.

[0039] An inductively coupled plasma is usually formed using a driving frequency of several MHz at a pressure of several hundred millitorr (mTorr). However, such an inductively coupled plasma has a weak induced electric field strength and it is difficult to perform discharge at atmospheric pressure or at several torr or higher. Therefore, a sufficient induced electric field strength is required, and a separate means for initial discharge is required.

[0040] When performing an inductively coupled plasma discharge by applying RF power to an induction coil surrounding a dielectric tube, the inductively coupled plasma heats the dielectric tube, and the dielectric tube is heated and damaged. Therefore, an inductively coupled plasma with an output power of several tens of kilowatts or more has structural limitations.

[0041] According to an embodiment of the present invention, in order to improve the efficiency or stability of a conventional inductively coupled plasma, 1) an antenna (coil structure) having a laminated structure for increasing the strength of the induced electric field, 2) dividing the induction coil and connecting a capacitor structure for impedance reduction between the divided induction coils, 3) a structure for connecting a main capacitor to both ends of the induction coil to satisfy the overall resonance condition, 4) improving the stability of the plasma of the induction coil, and applying a frequency-variable AC power supply unit, etc. Accordingly, it is possible to stably process a flow rate of several tens to several hundreds of liters per minute at a high pressure of several torr or more, which could not be achieved by a conventional inductively coupled plasma device. Also, an electrode for separate initial discharge is not required, and initial discharge is performed with the driving frequency of the AC power supply unit out of the resonance condition. When out of the resonance condition, a high voltage is applied to the induction coil to perform initial discharge. Next, the driving frequency of the AC power supply is changed to the resonance condition to perform main discharge.

[0042] The induction coil and the antenna are used interchangeably hereinafter with the same meaning. In the case of an inductively coupled plasma (ICP) antenna, the strength of the induced electric field transmitted to the plasma is proportional to the current and frequency of the induction coil and is proportional to the square of the number of turns. Therefore, the higher the number of turns of the induction coil (or antenna), the higher the electric field can be applied to the plasma. However, as the number of turns of the solenoid coil increases, energy is dispersed in the longitudinal direction of the dielectric discharge tube due to spatial constraints. Also, the high inductance (impedance) of the induction coil makes it difficult to transfer power from the RF power source (RF generator) to the induction coil (antenna).

[0043] Since the density of the electric field formed around the plasma must be increased, the number of turns per unit length must be maximized with respect to the longitudinal direction of the dielectric discharge tube. When a high voltage is applied to the induction coil, the induction coil forms a capacitive coupled plasma and reduces discharge stability. The capacitive coupled plasma is advantageous for initial discharge, but induces damage to the dielectric tube or the dielectric window that transmits the induction electric field due to ion acceleration by capacitive coupling.

[0044] According to an embodiment of the present invention, in order to solve the problem of breakage of the dielectric discharge tube due to the high voltage applied to the antenna, a capacitor is inserted between the unit antennas arranged in each layer. Accordingly, even when more power was applied to the antenna, the dielectric discharge tube was not damaged. A capacitor is used between the unit antennas to reduce the voltage applied to the antenna. Also, parasitic discharge due to the high voltage between the antenna, the power input terminal, and the power output terminal is suppressed.

[0045] When a high voltage is applied to the antenna, ions are accelerated and collided with the surface by the high voltage, inducing high-temperature heat generation and damage. Such problems make it difficult to apply high power conditions in inductively coupled plasma, and measures such as reducing the inductance or separating the antenna from the tube are taken.

[0046] According to an embodiment of the present invention, when a capacitor that appropriately cancels out the voltage is positioned in series between unit antennas constituting the antenna, the maximum potential decreases in inverse proportion to the number of times the antenna is divided, and even at high power, the breakage of the dielectric tube is reduced.

[0047] According to a comparative example of the present invention, experiments were conducted on the case where a capacitor is not applied to an antenna having the same inductance and the case where a capacitor is provided in series between unit antennas constituting the antenna. In the conventional antenna, the dielectric discharge tube was damaged even when providing 2 kW. However, in the case of the present invention, the dielectric discharge tube was not damaged even after applying 8 kW of power. Moreover, not only was it not damaged, but the discharge was also improved. Specifically, N2 gas that could not be introduced at a power of 4 kW or less from the conventional antenna could be introduced from a power of 1.5 kW after improvement.

[0048] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content is thorough and complete and that the concept of the present invention is fully conveyed to those skilled in the art. In the drawings, components are exaggerated for clarity. Throughout the specification, parts denoted by the same reference numerals indicate the same components.

[0049] FIG. 1 is a conceptual diagram for explaining a semiconductor substrate processing apparatus according to an embodiment of the present invention.

[0050] As shown in FIG. 1, the semiconductor substrate processing apparatus 2 includes a process chamber 92 for processing a substrate and an inductively coupled plasma generator 100 for providing active species formed by inductively coupled plasma to the process chamber.

[0051] The process chamber 92 deposits a thin film (e.g., a tungsten thin film) on the substrate 94. The process chamber 92 receives the supply of a first process gas such as WF6, and active species (e.g., hydrogen active species) are provided from the inductively coupled plasma generator 100. The active species are generated by a hydrogen (H2) plasma. The process chamber 92 includes a gas distribution unit 91. The gas distribution unit 91 receives the supply of the first process gas from the process gas supply unit 96, and active species are provided from the inductively coupled plasma device 91. The gas distribution unit 91 spatially distributes the gas provided for depositing a uniform thin film on the substrate.

[0052] The inductively coupled plasma generator 100 is a remote plasma source. The inductively coupled plasma generator 100 generates highly efficient hydrogen plasma at a high pressure in the level of several torrs. The inductively coupled plasma generator 100 includes an inductive discharge module 191 and an RF power supply 140 that supplies power to the inductive discharge module 101. The inductively coupled plasma generator 100 receives the supply of a second process gas, generates active species using inductively coupled plasma, and provides them to the process chamber 92.

[0053] The process chamber 92 includes a substrate holder 93 arranged in parallel facing the gas distribution unit 91 and a substrate 94 arranged on the substrate holder 93. The substrate holder 93 is heated for chemical vapor deposition. The substrate is a semiconductor substrate. More specifically, the substrate is a silicon semiconductor substrate. The process chamber 92 is evacuated by a vacuum pump 95.

[0054] According to a modified embodiment of the present invention, the active species are provided directly to the process chamber without passing through the gas distribution unit 91.

[0055] According to a modified embodiment of the present invention, the substrate processing apparatus is not limited to performing a chemical vapor deposition process, but performs various processes.

[0056] According to a modified embodiment of the present invention, the inductively coupled plasma device 100 is not limited to being used in a chemical vapor deposition process, but is used in a cleaning process of the process chamber. For example, the substrate processing apparatus 2 includes a separate remote plasma source, and the separate remote plasma source discharges NF3 and supplies it to the process chamber 92 to perform a cleaning process. In this case, since the process environment of the process chamber changes due to fluorine, the inductively coupled plasma device 100 of the present invention supplies hydrogen active species to the process chamber 92. Thereby, the fluorine adsorbed on the inner wall of the process chamber 92 reacts with the hydrogen active species and is removed.

[0057] FIG. 2A is a conceptual diagram illustrating an inductively coupled plasma generating device according to an embodiment of the present invention.

[0058] FIG. 2B is a circuit diagram illustrating the inductively coupled plasma generating device of FIG. 2A.

[0059] FIG. 2C is a drawing illustrating the voltage distribution of the inductively coupled plasma generating device of FIG. 2A.

[0060] FIG. 2D is a plan view illustrating the inductively coupled plasma generating device of FIG. 2A.

[0061] FIG. 2E is a plan view illustrating the induction coil of the inductively coupled plasma generating device of FIG. 2A.

[0062] As shown in FIGS. 2A to 2E, the inductively coupled plasma generating device 100 includes a dielectric tube 130 extending in the longitudinal direction, a first induction coil structure 110 disposed so as to surround the dielectric tube and generating inductively coupled plasma in the dielectric tube, an RF power supply 140 that provides positive and negative outputs with opposite phases to each other and supplies the positive and negative outputs of the RF power to both ends of the first induction coil structure respectively and changes the driving frequency, a first main capacitor 121 disposed between the positive output terminal of the RF power supply and one end of the first induction coil structure, and a second main capacitor 122 disposed between the negative output terminal of the RF power supply and the other end of the first induction coil structure.

[0063] The first induction coil structure 110 includes induction coils 112, 114, 116, 118 that are connected in series with each other, are respectively arranged in different layers, and each have at least one turn or more in each layer, and auxiliary capacitors 113, 115, 117 that are respectively arranged between adjacent induction coils and distribute the voltage applied to the induction coils.

[0064] The driving frequency of the RF power supply 140 is several hundred kHz to several MHz. The output power of the RF power supply 140 is several hundred watts to several tens of kilowatts. The RF power supply 140 supplies power to a time-varying load (inductive coupling plasma) through the first induction coil structure. The induction coils of the first induction coil structure 110 are electromagnetically coupled to the inductive coupling plasma. Therefore, a device capable of matching the impedance between the RF power supply 140 and the first induction coil structure 110 is required. The RF power supply 140 has a first output and a second output with opposite phases. At a specific time, the first output and the second output have opposite phases with respect to the ground.

[0065] A normal impedance matching network performs impedance matching using two variable reactance elements (for example, a vacuum variable capacitor) or a transformer. In this case, it is difficult for the first induction coil structure 110 to satisfy the driving frequency and stable resonance conditions. Therefore, an RF power supply with a variable driving frequency is used so that a pair of adjacent induction coils and auxiliary capacitors in the first induction coil structure satisfy the series resonance condition.

[0066] The dielectric tube 130 has a cylindrical shape and extends in the longitudinal direction. The material of the dielectric tube 130 is a glass, quartz, ceramic, alumina, or sapphire material that can withstand high temperatures. The inner diameter of the dielectric tube 130 is several tens of millimeters. The length of the dielectric tube 130 is several tens of centimeters. The cylindrical inductively coupled plasma device includes a cylindrical dielectric discharge tube and an antenna that wraps around the discharge tube. In a cylindrical inductively coupled plasma, since the induced electric field does not perpendicularly enter the dielectric discharge tube, damage due to ion bombardment is small. The cylindrical inductively coupled plasma generates an induced electric field in the central axis direction of the cylindrical dielectric discharge tube. However, if a high voltage is applied to the antenna, the antenna generates a capacitive coupled plasma and heats the dielectric tube. Therefore, a new inductive coil structure is required so that a high voltage is not applied to the antenna.

[0067] In the first inductive coil structure 110, the induced electric field depends on the driving frequency and the current (or the number of turns per unit length). Also, the maximum voltage applied to the first inductive coil structure 110 depends on the total impedance and the current of the first inductive coil structure 110. The impedance of the first inductive coil structure 110 depends on the inductance of the first inductive coil structure and the driving frequency. Therefore, in order to decrease the maximum voltage applied to the first inductive coil structure, if the inductance of the first inductive coil structure is increased, the strength of the induced electric field increases, but the capacitive coupling effect increases due to the high maximum voltage. Therefore, in order to decrease the impedance of the first inductive coil structure, the first inductive coil structure 10 includes a plurality of inductive coils 112, 114, 116, 118 and auxiliary capacitors 113, 115, 117 inserted between adjacent inductive coils. Also, the auxiliary capacitors adjacent to the inductive coils form a series resonance circuit with each other. The inductive coils and the auxiliary capacitors are electrically arranged alternately and are connected in series with each other. Thereby, the first inductive coil structure provides a low impedance overall. The number of the auxiliary capacitors is one less than the number of the inductive coils.

[0068] Further, the first inductive coil structure 110 forms a complete resonant circuit as a whole. For this purpose, the first main capacitor 121 is connected to one end of the first inductive coil structure 110, and the second main capacitor 122 is connected to the other end of the first inductive coil structure 110. On the other hand, in order to form a perfect resonant circuit, the capacitance C2 of the first main capacitor 121 is 2C1, which is twice the capacitance C1 of the auxiliary capacitor.

[0069] When such a resonant circuit is configured, the maximum voltage applied to the first inductive coil structure 110 is inversely proportional to the multiple by which it is divided among the respective inductive coils.

[0070] The first inductive coil structure 110 includes inductive coils 112, 114, 116, 118 that are connected in series with each other and are respectively arranged in different layers, with each layer having at least one turn or more, and auxiliary capacitors 113, 115 that are respectively arranged between adjacent inductive coils and distribute the voltage applied to the inductive coils.

[0071] The inductive coils include first to fourth inductive coils 112, 114, 116, 118. The auxiliary capacitors include first to third auxiliary capacitors 113, 115, 117. The inductance of each of the first to fourth inductive coils 112, 114, 116, 118 is the same and is L1. Also, the capacitance of each of the first to third auxiliary capacitors 113, 115, 117 is the same and is C1. Each of the first to third auxiliary capacitors 113, 115, 117 has 2C1 and is represented as a pair of virtual capacitors connected in series. Thereby, the first main capacitor 121, the first inductive coil 112, and the virtual capacitor form a resonant circuit to reduce the voltage as a whole.

[0072] When compared to the case where the auxiliary capacitors 113, 115, and 117 are not connected, by connecting the auxiliary capacitors, the voltage decreases in inverse proportion to the number of induction coils. Nevertheless, the number of turns per unit length of the overall dielectric tube is maintained. To satisfy such resonance conditions, the drive frequency is controlled to match the resonance frequency.

[0073] Also, in order to further increase the number of turns per unit length of the dielectric tube and increase the strength of the induced electric field, each of the induction coils 112, 114, 116, and 118 is a 3-turn coil or a 4-turn coil. The induction coils 112, 114, 116, and 118 are stacked vertically and densely enough with each other to require space for electrical connection. To satisfy this, each induction coil does not have a part that jumps across the arrangement plane, and the input end and the output end of each induction coil should not be arranged at the part where they are stacked with each other. For this purpose, the following induction coils are proposed.

[0074] The induction coils 112, 114, 116, and 118 include first to fourth induction coils 112, 114, 116, and 118 stacked in order. The auxiliary capacitors 113, 115, and 117 include first to third auxiliary capacitors 113, 115, and 117.

[0075] The auxiliary capacitors between each induction coil reverse the potential in the opposite direction. That is, the turns (or the first arc part) close to the dielectric tube and the turns (the fourth arc part) farthest from it on the same arrangement plane are induced to have opposite potentials to each other. Inside the dielectric tube, the potentials of the induction coils cancel each other out, and no electrostatic field due to the storage coupling towards the dielectric tube appears. Such a decrease in the electrostatic field reduces the storage coupling effect.

[0076] In a general antenna, a large potential difference is generated across both ends due to inductance. The large potential difference accelerates ions, inducing energy loss and heating and damaging the dielectric tube. However, the auxiliary capacitor placed between the induction coils reduces the potential difference and sets the potentials inside and outside each induction coil to be opposite to each other. As a result, the potentials of opposite signs operate within the dielectric tube by the dipole field to reduce the electrostatic field. Each of the induction coils 112, 114, 116, 118 includes a plurality of windings wound from the inside to the outside in the same plane.

[0077] The first induction coil 112 is arranged to surround the dielectric tube. The second induction coil 114, in the case where the first induction coil 112 is arranged, is rotated 90 degrees counterclockwise and arranged to be aligned below the first induction coil 112. The third induction coil 116, in the case where the second induction coil 114 is arranged, is rotated 90 degrees counterclockwise and arranged to be aligned below the second induction coil 114. The fourth induction coil 118, in the case where the third induction coil 116 is arranged, is rotated 90 degrees counterclockwise and arranged to be aligned below the third induction coil 116. One end of the first induction coil 112 is connected to the positive output end of the RF power supply 140 through the first main capacitor 121. The other end of the first induction coil 112 is connected to one end of the second induction coil 114 through the first auxiliary capacitor 113. The other end of the second induction coil 114 is connected to one end of the third induction coil 116 through the second auxiliary capacitor 115. The other end of the third induction coil 116 is connected to one end of the fourth induction coil 118 through the third auxiliary capacitor 117. The other end of the fourth induction coil 118 is connected to the negative output end of the RF power supply 140 through the second main capacitor 122. The first to fourth induction coils are rotated by 90 degrees each and stacked in order to maintain overall azimuthal symmetry.

[0078] The voltage of the innermost winding of each induction coil (e.g., 2V) has a phase opposite to that of the outermost winding (e.g., -2V). Also, the voltages of the innermost windings of all induction coils are the same. This minimizes the parasitic capacitance between adjacent induction coils and improves the discharge characteristics. Further, since the plasma inside the dielectric tube exhibits the same voltage due to the inner winding, local ion sputtering is reduced.

[0079] The induction coil is divided and an auxiliary capacitor is inserted between the divided induction coils to reduce the maximum voltage. However, in order to provide a sufficient induction electric field, it is necessary to increase the number of turns per unit length. To increase the number of turns per unit length, the number of turns of each induction coil 112, 114, 116, 118 is increased. However, each induction coil needs to be arranged in the same arrangement plane. If each induction coil has wiring that deviates from the arrangement plane, it obstructs the dense stacking of induction coils arranged in adjacent layers. Each induction coil has 3 or 4 turns in the same arrangement plane.

[0080] According to a modified embodiment of the present invention, the number of turns of each induction coil is modified to 5 turns or more.

[0081] Each of the induction coils 112, 114, 116, and 118 has a portion open in the first direction (x-axis direction) in a rectangular coordinate system, has a first central angle, is disposed in a placement plane, and has a first arc portion 22a having a constant first radius; a second arc portion 22b having a second central angle equal to or less than the first central angle, disposed in the placement plane, having a second radius larger than the first radius, and arranged to have the same central axis as the central axis of the first arc portion 22a; a third arc portion 22c having a third central angle equal to or less than the second central angle, disposed in the placement plane, having a third radius larger than the second radius, and arranged to have the same central axis as the central axis of the first arc portion; a fourth arc portion 22d having a fourth central angle equal to or less than the third central angle, disposed in the placement plane, having a fourth radius larger than the third radius, and arranged to have the same central axis as the central axis of the first arc portion; a first connecting portion 23a disposed in the placement plane, connected to one end of the first arc portion 22a, and extending in the first direction (x-axis direction); a "U"-shaped first arc connecting portion 24a disposed in the placement plane and connecting the other end of the first arc portion 22a and one end of the second arc portion 22b; a "U"-shaped second arc connecting portion 24b disposed in the placement plane and connecting the other end of the second arc portion and one end of the third arc portion; a "U"-shaped third arc connecting portion 24c disposed in the placement plane and connecting the other end of the third arc portion and one end of the fourth arc portion; and a second connecting portion 23b disposed in the placement plane, connected to the other end of the fourth arc portion 22d, and extending in the first direction. The fourth central angle is 270 degrees or more. The first arc connecting portion 24a, the second arc connecting portion 24b, and the third arc connecting portion 24c are arranged so as not to overlap each other. The first arc connecting portion 24a is disposed within the region defined by the second arc connecting portion 24b.

[0082] In each of the induction coils 112, 114, 116, and 118, the interval between windings (for example, the first to fourth arc portions) is constant. For example, the interval is 1 mm to 3 mm. In order for the induction coil to provide sufficient azimuthal symmetry, the first to fourth central angles are 270 degrees or more. On the other hand, the first to fourth arc portions maintain a sufficient interval of several millimeters or more to suppress arc discharge at atmospheric pressure due to the voltage difference.

[0083] The induction coils arranged in adjacent layers are electrically insulated by the insulating spacer 150. The insulating spacer 150 is inserted into the outer surface of the dielectric tube 130 in the form of a washer and is a thin disk-shaped with a through hole in the center. The insulating spacer 150 is made of glass, plastic, or Teflon. The thickness of the insulating spacer 150 is at the millimeter level. The inner radius of the insulating spacer 150 is substantially the same as the outer radius of the dielectric tube 130, and the outer radius of the insulating spacer 150 is substantially the same as the outermost shell radius of the induction coil. The width between the inner radius and the outer radius of the insulating spacer 150 is several centimeters to several tens of centimeters.

[0084] On the other hand, at least a part of the induction coils 112, 114, 116, and 118 is molded by a ceramic paste. The ceramic mold 152 that wraps at least a part of the induction coil is in thermal contact with the dielectric tube 130. Thus, when a refrigerant flows in the induction coils 112, 114, 116, and 118, the cooled induction coil cools the ceramic mold 152, and the ceramic mold 152 indirectly cools the dielectric tube 130.

[0085] Each of the induction coils 112, 114, 116, and 118 is wound four times outward from the dielectric tube in each layer. A pair of induction coils in adjacent layers are connected in series through an auxiliary capacitor connected in series therebetween. As a result, the capacitance of the auxiliary capacitor cancels out the inductance of the induction coil. The four induction coils form one group. The four induction coils are arranged by rotating them at 90-degree intervals counterclockwise.

[0086] Both ends of the dielectric tube are sealed by flanges. The upper flange 132 fixes one end of the dielectric tube and includes a nozzle 131 that provides a mixed gas of hydrogen and nitrogen. The induction coils 112, 114, 116, and 118 that surround the central portion of the dielectric tube generate inductively coupled plasma in the dielectric tube. The lower flange 134 fixes the other end of the dielectric tube, and a gas that is additionally decomposed by the inductively coupled plasma is provided at the other end of the dielectric tube.

[0087] Figure 3A is a conceptual diagram illustrating an inductively coupled plasma generation device according to another embodiment of the present invention.

[0088] Figure 3B is a circuit diagram illustrating the inductively coupled plasma generation device of Figure 3A.

[0089] Figure 3C is a drawing illustrating the voltage distribution of the induction coil structure of the inductively coupled plasma generation device of Figure 3A.

[0090] As shown in FIGS. 3A to 3C, the inductively coupled plasma generating apparatus 200 includes a dielectric tube 130 extending in the longitudinal direction, a first inductive coil structure 110 disposed so as to surround the dielectric tube and generate inductively coupled plasma in the dielectric tube, an RF power supply 140 that provides a positive output and a negative output having opposite phases to each other, supplies the positive output and the negative output of RF power to both ends of the first inductive coil structure respectively, and changes a driving frequency, a first main capacitor 121 disposed between the positive output terminal of the RF power supply and one end of the first inductive coil structure, and a second main capacitor 122 disposed between the negative output terminal of the RF power supply and the other end of the first inductive coil structure.

[0091] A second inductive coil structure 210 is disposed so as to surround the dielectric tube 130, is disposed at a distance from the first inductive coil structure 110 in the longitudinal direction, has the same structure as the first inductive coil structure 110, and generates inductively coupled plasma in the dielectric tube 130.

[0092] One end of the second inductive coil structure 210 is connected to one end of the first inductive coil structure 110, and the other end of the second inductive coil structure 210 is connected to the other end of the first inductive coil structure 110. The first inductive coil structure 110 and the second inductive coil structure 210 are connected in parallel with each other between the first main capacitor 121 and the second main capacitor 122.

[0093] Each of the inductive coils 112, 114, 116, 118 constituting the first inductive coil structure 110 and the second inductive coil structure 210 has the same first inductance L1. Each of the auxiliary capacitors 113, 115, 117 constituting the first inductive coil structure 110 and the second inductive coil structure 210 has the same first capacitance C1. The driving frequency of the RF power supply 140 is controlled to match the resonance frequency by the first inductance L1 and the first capacitance C1 connected in series.

[0094] The first main capacitor and the second main capacitor each have the same second capacitance C2, and the second capacitance C2 is four times the first capacitance C1.

[0095] One end of the first induction coil structure 110 and one end of the second induction coil structure 210 are arranged adjacent to each other. One end of the first induction coil structure and one end of the second induction coil structure are connected to each other and connected to the first main capacitor 121. The other end of the first induction coil structure 110 and the other end of the second induction coil structure 210 are connected to each other and connected to the second main capacitor.

[0096] The first induction coil structure 110 and the second induction coil structure 210 are arranged symmetrically with respect to a point on the dielectric discharge tube 130 in an up / down mirror image. The current is dispersed from the center up / down and then converges again at both ends.

[0097] Also, the first induction coil structure 110 and the second induction coil structure 210 entirely form a complete resonance circuit. To achieve this, the first main capacitor 121 is connected to one end of the first induction coil structure 110 and one end of the first induction coil structure 210. The second main capacitor 122 is connected to the other end of the first induction coil structure 110 and the other end of the second induction coil structure. On the other hand, to form a perfect resonance circuit, the capacitance C2 of the first main capacitor 121 is four times 4C1 the capacitance C1 of the auxiliary capacitor. The first main capacitor is shown as a capacitor having 2C1 and connected in parallel with each other.

[0098] The induction coil includes first to fourth induction coils 112, 114, 116, and 118. The auxiliary capacitor includes first to third auxiliary capacitors 113, 115, and 117. The inductance of each of the first to fourth induction coils 112, 114, 116, and 118 is the same and is L1. Also, the capacitance of each of the first to third auxiliary capacitors 113, 115, and 117 is the same and is C1. Each of the first to third auxiliary capacitors 113, 115, and 117 has 2C1 and is represented as a pair of virtual capacitors connected in series. Thereby, a part 2C1 of the first main capacitor 121, the first induction coil 112, and the virtual capacitor 2C1 constitute a resonance circuit to reduce the voltage as a whole.

[0099] The first induction coil structure 110 and the second induction coil structure 210 are connected in parallel with each other and include a total of eight induction coils. The induction coils of the first induction coil structure are arranged in turn at 90-degree intervals counterclockwise. The induction coils of the second induction coil structure are arranged in turn at 90-degree intervals clockwise.

[0100] An auxiliary capacitor for canceling the imaginary part of the impedance is arranged between the induction coils. Two groups of the first induction coil structure and the second induction coil structure, each having four induction coils connected in series, are electrically connected to an external terminal after both ends are connected in parallel with each other.

[0101] The auxiliary capacitor between each induction coil reverses the potential in the opposite direction. That is, the innermost turn (or the first arc portion) and the outermost turn (the fourth arc portion) of the dielectric tube in the same arrangement plane are induced to have opposite potentials. Inside the dielectric tube, the potentials of the induction coils are canceled, and no electrostatic field due to the electric charge coupling to the dielectric tube appears. Such a decrease in the electrostatic field reduces the electric charge coupling effect.

[0102] In a general antenna, a large potential difference is generated at both ends due to inductance. The large potential difference accelerates ions, inducing energy loss, heating and damaging the dielectric tube. However, the auxiliary capacitor placed between the induction coils reduces the potential difference and sets the potentials inside and outside each induction coil to be opposite to each other. As a result, the potentials with opposite signs operate in the dielectric tube by the dipole field to reduce the electrostatic field.

[0103] FIG. 4A is a conceptual diagram illustrating an inductively coupled plasma generation apparatus according to still another embodiment of the present invention.

[0104] FIG. 4B is a circuit diagram illustrating the inductively coupled plasma generation apparatus of FIG. 4A.

[0105] FIG. 4C is a drawing illustrating the voltage distribution of the induction coil structure of the inductively coupled plasma generation apparatus of FIG. 4A.

[0106] FIG. 4D is a plan view illustrating the induction coil of the inductively coupled plasma generation apparatus of FIG. 4A.

[0107] As shown in FIGS. 4A to 4D, the inductively coupled plasma generation apparatus 300 includes a dielectric tube 130 extending in the longitudinal direction, a first induction coil structure 310 disposed so as to surround the dielectric tube and generating inductively coupled plasma in the dielectric tube, an RF power supply 140 providing positive and negative outputs with opposite phases, supplying the positive and negative outputs of RF power to both ends of the first induction coil structure respectively, and changing the driving frequency, a first main capacitor 121 disposed between the positive output terminal of the RF power supply and one end of the first induction coil structure, and a second main capacitor 122 disposed between the negative output terminal of the RF power supply and the other end of the first induction coil structure.

[0108] The first main capacitor 121 and the second main capacitor 122 each have the same second capacitance C2, and the second capacitance C2 is twice the first capacitance C1 of the auxiliary capacitor.

[0109] The induction coil includes first to fourth induction coils 312, 314, 316, and 318. The auxiliary capacitor includes first to third auxiliary capacitors 113, 115, and 117. The inductance of each of the first to fourth induction coils 312, 314, 316, 318 is the same and is L1. Also, the capacitance of each of the first to third auxiliary capacitors 113, 115, 117 is the same and is C1. Each of the first to third auxiliary capacitors 113, 115, 117 has 2C1 and is represented as a pair of virtual capacitors connected in series. Thereby, a part 2C1 of the first main capacitor 121, the first induction coil 312, and the virtual capacitor 2C1 constitute a resonance circuit and overall reduce the voltage.

[0110] Each of the induction coils 312, 314, 316, 318 has a portion opened in a first direction in a rectangular coordinate system, has a first central angle, is disposed in an arrangement plane, and has a first arc portion 32a having a constant first radius; has a second central angle less than or equal to the first central angle, is disposed in the arrangement plane, has a second radius larger than the first radius, and is disposed so as to have the same central axis as the central axis of the first arc portion; a third arc portion 32c having a third central angle less than or equal to the second central angle, being disposed in the arrangement plane, having a third radius larger than the second radius, and being disposed so as to have the same central axis as the central axis of the first arc portion; a first connecting portion 33a disposed in the arrangement plane, connected to one end of the first arc portion, and extending in the first direction; a first arc connecting portion 34a in a "U" shape disposed in the arrangement plane, connecting the other end of the first arc portion and one end of the second arc portion; a second arc connecting portion 34b in a "U" shape disposed in the arrangement plane, connecting the other end of the second arc portion and one end of the third arc portion; and a second connecting portion 33b disposed in the arrangement plane, connected to the other end of the third arc portion, and extending in the first direction. The third central angle is 270 degrees or more.

[0111] FIG. 5A is a conceptual diagram for explaining an inductively coupled plasma generating apparatus according to another embodiment of the present invention.

[0112] FIG. 5B is a plan view for explaining an induction coil of the inductively coupled plasma generating apparatus of FIG. 5A.

[0113] As shown in FIGS. 5A to 5B, the inductively coupled plasma generating apparatus 400 includes a dielectric tube 130 extending in the longitudinal direction, a first induction coil structure 410 disposed so as to surround the dielectric tube and generating inductively coupled plasma in the dielectric tube, an RF power supply 140 providing positive and negative outputs having opposite phases to each other, supplying the positive and negative outputs of RF power to both ends of the first induction coil structure respectively, and changing a driving frequency, a first main capacitor 121 disposed between a positive output terminal of the RF power supply and one end of the first induction coil structure, and a second main capacitor 122 disposed between a negative output terminal of the RF power supply and the other end of the first induction coil structure.

[0114] The first main capacitor 121 and the second main capacitor 122 each have the same second capacitance C2, and the second capacitance C2 is twice the first capacitance C1 of the auxiliary capacitor. The induction coil includes first to fourth induction coils 412, 414, 416, 418. The auxiliary capacitor includes first to third auxiliary capacitors 113, 115, 117. The inductance of each of the first to fourth induction coils 412, 414, 416, 418 is the same and is L1. Also, the capacitance of each of the first to third auxiliary capacitors 113, 115, 117 is the same and is C1. Each of the first to third auxiliary capacitors 113, 115, 117 has 2C1 and is represented as a pair of virtual capacitors connected in series. Thereby, a part 2C1 of the first main capacitor 121, the first induction coil 412, and the virtual capacitor 2C1 constitute a resonance circuit to reduce the voltage as a whole.

[0115] Each of the induction coils 412, 414, 416, and 418 has a portion open in the first direction in a rectangular coordinate system, has a first central angle, is disposed in a disposed plane, and has a first arc portion 42a having a constant first radius; a second arc portion 42b having a second central angle less than or equal to the first central angle, disposed in the disposed plane, having a second radius larger than the first radius, and disposed so as to have the same central axis as the central axis of the first arc portion; a first connecting portion 43a disposed in the disposed plane, connected to one end of the first arc portion, and extending in the first direction; a "U"-shaped first arc connecting portion 44a disposed in the disposed plane, connecting the other end of the first arc portion and one end of the second arc portion; and a second connecting portion 43b disposed in the disposed plane, connected to the other end of the second arc portion, and extending in the first direction. The second central angle is 270 degrees or more.

[0116] As described above, the present invention has been illustrated and described with respect to specific preferred embodiments. However, the present invention is not limited to such embodiments, and includes all embodiments in various forms that can be implemented without departing from the technical idea of the present invention claimed in the claims by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

[0117] 110 First induction coil structure 112, 114, 116, 118 Induction coil 113, 115, 117 Auxiliary storage battery 121 First main storage battery 122 Second main storage battery

Claims

1. A plasma generating device comprising a discharge tube and an antenna structure, wherein the discharge tube is configured to provide an internal space in which plasma is generated, the antenna structure is disposed on the outer periphery of the discharge tube and is configured to induce the plasma into the internal space of the discharge tube in response to supplied AC power, the antenna structure includes (i) a first layer antenna disposed on a first plane perpendicular to the central axis of the discharge tube, (ii) a second layer antenna disposed on a second plane different from the first plane and perpendicular to the central axis, and (iii) an interlayer capacitor electrically inserted between the first layer antenna and the second layer antenna, the first layer antenna includes a first turn antenna portion having a first radius of curvature and a second turn antenna portion having a second radius of curvature larger than the first radius of curvature, and one end of the first turn antenna portion is electrically connected to one end of the second turn antenna portion, the second layer antenna includes a third turn antenna portion having the first radius of curvature and a fourth turn antenna portion having the second radius of curvature, and one end of the third turn antenna portion is electrically connected to one end of the fourth turn antenna portion, the interlayer capacitor electrically connects the other end of the first turn antenna portion to the other end of the fourth turn antenna portion, when viewed in the direction of the central axis of the discharge tube, a first virtual line is formed by connecting the center point of the discharge tube and the other end of the first turn antenna, and when viewed in the direction of the central axis of the discharge tube, a second virtual line is formed by connecting the center point of the discharge tube and the other end of the third turn antenna, the first layer antenna and the second layer antenna are arranged such that an angle between the first virtual line and the second virtual line is a predetermined angle other than 0 degrees, the plasma generating device.

2. The plasma generating device according to claim 1, wherein the predetermined angle is less than 180 degrees.

3. The plasma generating device according to claim 1, wherein the predetermined angle is less than or equal to 90 degrees.

4. The first turn of the first layer antenna is the innermost turn of the first layer antenna, The plasma generating device according to claim 1, wherein the fourth turn of the second layer antenna is the outermost turn of the second layer antenna.

5. The antenna structure includes N layer antennas, and the M-th layer antenna among the N layer antennas is disposed on the M-th plane among N planes perpendicular to the central axis, where M is equal to or smaller than N and is a natural number. The plasma generating device according to claim 1, wherein the first layer antenna is the (M - 1)-th layer antenna and the second layer antenna is the M-th layer antenna.

6. The plasma generating device according to claim 1, wherein the potential difference between the first turn of the first layer antenna and the fourth turn of the second layer antenna is minimized due to the predetermined angle.

7. The plasma generating device according to claim 1, wherein the potential difference between the second turn of the first layer antenna and the third turn of the second layer antenna is minimized due to the predetermined angle.

8. An antenna structure having a shape that can be disposed on the outer periphery of a discharge tube so as to induce plasma in the internal space of the discharge tube in response to supplied AC power, the antenna structure including: a first layer antenna disposed on a first plane perpendicular to the central axis of the antenna structure; a second layer antenna disposed on a second plane different from the first plane and perpendicular to the central axis; a layer capacitor electrically inserted between the first layer antenna and the second layer antenna; and comprising: The first layer antenna includes a first turn antenna portion having a first radius of curvature and a second turn antenna portion having a second radius of curvature larger than the first radius of curvature, and one end of the first turn antenna portion is electrically connected to one end of the second turn antenna portion. The second layer antenna includes a third turn antenna portion having the first radius of curvature and a fourth turn antenna portion having the second radius of curvature, and one end of the third turn antenna portion is electrically connected to one end of the fourth turn antenna portion. The layer capacitor electrically connects the other end of the first turn antenna portion to the other end of the fourth turn antenna portion. When viewed in the direction of the central axis of the antenna structure, a first virtual line is formed by connecting the center point of the antenna structure and the other end of the first turn antenna, and when viewed in the direction of the central axis of the antenna structure, a second virtual line is formed by connecting the center point of the antenna structure and the other end of the third turn antenna. The first-layer antenna and the second-layer antenna are arranged such that the angle between the first virtual line and the second virtual line is a predetermined angle other than 0 degrees, the antenna structure.

9. The predetermined angle is less than 180 degrees, the antenna structure according to claim 8.

10. The predetermined angle is less than or equal to 90 degrees, the antenna structure according to claim 8.

11. The first turn of the first-layer antenna is the innermost turn of the first-layer antenna, The fourth turn of the second-layer antenna is the outermost turn of the second-layer antenna, the antenna structure according to claim 8.

12. The antenna structure includes N layer antennas, and the Mth layer antenna among the N layer antennas is arranged on the Mth plane among the N planes perpendicular to the central axis, M is equal to or less than N and is a natural number, The first-layer antenna is the (M-1)th layer antenna, and the second-layer antenna is the Mth layer antenna, the antenna structure according to claim 8.

13. The potential difference between the first turn of the first-layer antenna and the fourth turn of the second-layer antenna is minimized due to the predetermined angle, the antenna structure according to claim 8.

14. The potential difference between the second turn of the first-layer antenna and the third turn of the second-layer antenna is minimized due to the predetermined angle, the antenna structure according to claim 8.

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