Plasma generating device

Abstract

Provided is a technology capable of improving uniformity of a plasma density. This plasma generating device is provided with: a first helical coil structure having a first helical shape and including a first inner monopole antenna disposed along the first helical shape, and a first outer monopole antenna disposed along the first helical shape to be spaced apart from the first inner monopole antenna; a second helical coil structure having a second helical shape and including a second inner monopole antenna disposed so as to nest within the first helical coil structure on the same plane and disposed along the second helical shape, and a second outer monopole antenna disposed along the second helical shape to be spaced apart from the second inner monopole antenna.

Description

Plasma generation device

[0001] The present disclosure relates to a plasma generation device.

[0002] As a technology related to a plasma generation device including an antenna in an inductively coupled plasma processing device, for example, the one described in Patent Document 1 is known.

[0003] International Publication No. 20 / 076413

[0004] The present disclosure provides a technology capable of improving the uniformity of plasma density.

[0005] A plasma generation device according to an aspect of the present disclosure is a first spiral coil structure having a first spiral shape, and the first spiral coil structure includes a first inner monopole antenna arranged along the first spiral shape, and a first outer monopole antenna spaced apart from the first inner monopole antenna and arranged along the first spiral shape. The first inner monopole antenna has a first terminal that is an open end and a second terminal arranged outside the first terminal. The first outer monopole antenna has a third terminal that is an open end and a fourth terminal arranged inside the third terminal. The plasma generation device further includes a second spiral coil structure having a second spiral shape, and the second spiral coil structure is arranged to be nested on the same plane as the first spiral coil structure. The second spiral coil structure includes a second inner monopole antenna arranged along the second spiral shape, and a second outer monopole antenna spaced apart from the second inner monopole antenna and arranged along the second spiral shape. The second inner monopole antenna has a fifth terminal that is an open end and a sixth terminal arranged outside the fifth terminal. The second outer monopole antenna has a seventh terminal that is an open end and an eighth terminal arranged inside the seventh terminal.

[0006] According to the present disclosure, a technology capable of improving the uniformity of plasma density can be provided.

[0007] This is a diagram illustrating an example of the configuration of a plasma processing system. This is a diagram illustrating an example of the configuration of an inductively coupled plasma processing apparatus. This is a plan view showing an example of a plasma generator. This is a diagram illustrating an example of the electrical connection state of the plasma generator shown in Figure 3A. This is a plan view showing a modified version of the plasma generator. This is a plan view showing a modified version of the plasma generator. This is a diagram illustrating an example of the electrical connection state of the plasma generator shown in Figure 5A. This is a plan view showing a modified version of the plasma generator. This is a diagram illustrating an example of the electrical connection state of the plasma generator shown in Figure 6A. This is a plan view showing a modified version of the plasma generator. This is a plan view showing a modified version of the plasma generator.

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, a first helical coil structure having a first helical shape, the first helical coil structure comprising a first inner monopole antenna arranged along the first helical shape, and a first outer monopole antenna spaced apart from the first inner monopole antenna and arranged along the first helical shape, wherein the first inner monopole antenna has a first terminal which is an open end and a second terminal which is located outside the first terminal, and the first outer monopole antenna has a third terminal which is an open end and a fourth terminal which is located inside the third terminal, and a second helical coil structure having a second helical shape. A plasma generating apparatus is provided, comprising a second helical coil structure, which is arranged to be nested on the same plane as the first helical coil structure, and the second helical coil structure includes a second inner monopole antenna arranged along the second helical shape and a second outer monopole antenna spaced apart from the second inner monopole antenna and arranged along the second helical shape, the second inner monopole antenna having a fifth terminal which is an open end and a sixth terminal which is located outside the fifth terminal, and the second outer monopole antenna having a seventh terminal which is an open end and an eighth terminal which is located inside the seventh terminal.

[0010] In one exemplary embodiment, each of the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna has a length of one-quarter wavelength of the electromagnetic wave propagating through the antenna.

[0011] In one exemplary embodiment, a first coil segment included in a first helical coil structure and a second coil segment included in a second helical coil structure are arranged adjacent to each other, and the currents flowing through the first coil segment and the second coil segment are in the same direction.

[0012] In one exemplary embodiment, on the same plane, the first and fifth terminals are positioned opposite each other at positions offset 180 degrees spirally from the center of the spiral and are equally distanced from the center; the second and sixth terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center; the third and seventh terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center; and the fourth and eighth terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center.

[0013] In one exemplary embodiment, one of the second and fourth terminals and one of the sixth and eighth terminals are electrically connected to a common RF power supply, and the current flowing through one of the second and fourth terminals and the current flowing through one of the sixth and eighth terminals are in phase with each other.

[0014] In one exemplary embodiment, the other of the second and fourth terminals and the other of the sixth and eighth terminals are electrically connected to the ground potential.

[0015] In one exemplary embodiment, the common RF power supply is a variable frequency power supply.

[0016] In one exemplary embodiment, the fourth and eighth terminals are electrically connected to a common RF power supply, and the currents flowing through the fourth and eighth terminals are in phase with each other.

[0017] In one exemplary embodiment, the second and sixth terminals are electrically connected to the ground potential.

[0018] In one exemplary embodiment, the common RF power supply is a variable frequency power supply.

[0019] In one exemplary embodiment, the system includes two or more spiral sets, each consisting of four monopole antennas: a first inner monopole antenna, a first outer monopole antenna, a second inner monopole antenna, and a second outer monopole antenna.

[0020] In one exemplary embodiment, the second, fourth, sixth, and eighth terminals are electrically connected to a common RF power supply via a balun transformer, and the currents flowing through the second and sixth terminals and the currents flowing through the fourth and eighth terminals are in opposite phase to each other.

[0021] In one exemplary embodiment, the common RF power supply is a variable frequency power supply.

[0022] In one exemplary embodiment, the system further comprises a drive coil structure electrically connected to an RF power supply and configured to inductively couple with a first helical coil structure and a second helical coil structure, wherein the second, fourth, sixth, and eighth terminals are electrically connected to a variable capacitor.

[0023] In one exemplary embodiment, the drive coil structure includes a first drive coil electrically connected to an RF power supply and a second drive coil electrically connected to the RF power supply and arranged to be nested with the first drive coil, wherein a first drive coil segment included in the first drive coil and a second drive coil segment included in the second drive coil are arranged adjacent to each other, and the direction of the current flowing through the first drive coil segment and the second drive coil segment is the same.

[0024] In one exemplary embodiment, a first helical coil structure having a first inner monopole antenna and a first outer monopole antenna spaced apart from the first inner monopole antenna, wherein the first inner monopole antenna has a first terminal which is an open end and a second terminal which is located outside the first terminal, and the first outer monopole antenna has a third terminal which is an open end and a fourth terminal which is located inside the third terminal, and the first helical coil structure is nested on the same plane as the first helical coil structure. A plasma generating apparatus is provided, comprising a second helical coil structure arranged in such a manner, the second helical coil structure having a second inner monopole antenna and a second outer monopole antenna spaced apart from the second inner monopole antenna, the second inner monopole antenna having a fifth terminal which is an open end and a sixth terminal which is located outside the fifth terminal, and the second outer monopole antenna having a seventh terminal which is an open end and an eighth terminal which is located inside the seventh terminal.

[0025] In one exemplary embodiment, each of the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna has a length of one-quarter wavelength of the electromagnetic wave propagating through the antenna.

[0026] In one exemplary embodiment, a first coil segment included in a first helical coil structure and a second coil segment included in a second helical coil structure are arranged adjacent to each other, and the direction of the current flowing through the first coil segment and the second coil segment is the same.

[0027] In one exemplary embodiment, the second, fourth, sixth, and eighth terminals are located on a hypothetical straight line extending radially outward from the center of the helix, while remaining on the same plane.

[0028] In one exemplary embodiment, on the same plane, the first and fifth terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center; the second and sixth terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center; the third and seventh terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center; and the fourth and eighth terminals are positioned opposite each other at positions offset 180 degrees spirally from the center and are equally distanced from the center.

[0029] Next, exemplary embodiments of the present disclosure will be described with reference to the attached drawings. In each drawing, components denoted by the same reference numerals have the same or similar configurations.

[0030] <Example of a Plasma Processing System> Figure 1 is a diagram illustrating an example of the configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0031] The plasma generation unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR (Electron Cyclotron Resonance) plasma, helicon wave excited plasma (HWP), or surface wave plasma (SWP), etc. Various types of plasma generation units, including AC (Alternating Current) plasma generation units and DC (Direct Current) plasma generation units, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0032] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control the elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions realized by the processing unit 2a1 described herein may be implemented in a circuit or processing circuit, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), a conventional circuit, and / or a combination thereof, programmed to realize the described functions. The processor is considered to be a circuit or processing circuit, including transistors and other circuits. The processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0033] The following describes an example configuration of an inductively coupled plasma processing apparatus as an example of a plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of an inductively coupled plasma processing apparatus.

[0034] The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window 101. The plasma processing apparatus 1 also includes a substrate support unit 11, a gas introduction unit, and an antenna 14. The substrate support unit 11 is located inside the plasma processing chamber 10. The antenna 14 is located on or above the plasma processing chamber 10 (i.e., on or above the dielectric window 101). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 101, the side walls 102 of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded.

[0035] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0036] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a bias electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or on both the electrostatic chuck 1111 and the annular insulating member. Also, at least one bias electrode, electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed inside the ceramic member 1111a. Furthermore, the conductive member of the base 1110 and the bias electrode inside the ceramic member 1111a may function as multiple bias electrodes. Also, the electrostatic chuck electrode 1111b may function as a bias electrode. Therefore, the substrate support portion 11 includes at least one bias electrode.

[0037] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0038] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0039] The gas introduction section is configured to introduce at least one processing gas from the gas supply section 20 into the plasma processing space 10s. In one embodiment, the gas introduction section includes a central gas injector (CGI) 13. The central gas injector 13 is located above the substrate support section 11 and is attached to a central opening formed in the dielectric window 101. The central gas injector 13 has at least one gas supply port 13a, at least one gas flow path 13b, and at least one gas inlet 13c. The processing gas supplied to the gas supply port 13a passes through the gas flow path 13b and is introduced into the plasma processing space 10s from the gas inlet 13c. In addition to or instead of the central gas injector 13, the gas introduction section may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 102.

[0040] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one processing gas to the gas inlet from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of at least one processing gas.

[0041] The power supply system 30 includes a power supply 31 that is electrically connected to or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected to or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The power supply 31 is configured to supply at least one RF signal (RF power) to at least one bias electrode and antenna 14. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to at least one bias electrode, a bias potential is generated on the substrate W, and ions in the formed plasma can be drawn into the substrate W.

[0042] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected to or coupled to the antenna 14 and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected to or coupled to the antenna 14 via at least one impedance matcher. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to the antenna 14.

[0043] The second RF generation unit 31b is electrically connected or coupled to at least one bias electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected or coupled to at least one bias electrode via at least one impedance matcher. The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency within the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one bias electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0044] The power supply system 30 may also include a power supply 32 that is electrically connected or coupled to the plasma processing chamber 10. The power supply 32 includes a voltage generation unit 32a. In one embodiment, the voltage generation unit 32a is electrically connected or coupled to at least one bias electrode and is configured to generate a voltage signal. The generated voltage signal is applied to at least one bias electrode.

[0045] In various embodiments, the voltage signal may be pulsed. In this case, the voltage generation unit 32a functions as a voltage pulse generation unit configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one bias electrode. In one embodiment, the sequence of voltage pulses has multiple cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, the burst of voltage pulses is repeated in the sequence of voltage pulses. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangular, trapezoidal, triangular, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Note that the voltage generation unit 32a may be provided in addition to the power supply 31, or it may be provided in place of the second RF generation unit 31b.

[0046] The antenna 14 includes one or more coils. In one embodiment, the antenna 14 may include an outer coil and an inner coil arranged coaxially. In this case, the power supply 31 may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generation unit may be connected to both the outer coil and the inner coil, or separate RF generation units may be connected to the outer coil and the inner coil separately.

[0047] The exhaust system 40 may be connected to, for example, a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0048] <Example of Plasma Generation Device> FIG. 3A is a plan view showing an example of a plasma generation device. The plasma generation device 14 shown in FIG. 3A is an example of the antenna 14 shown in FIG. 2. As shown in FIG. 3A, the plasma generation device 14 includes a first helical coil structure 60 and a second helical coil structure 70. The first helical coil structure 60 and the second helical coil structure 70 are arranged on the same plane above the plasma processing device 1 or above it. The first helical coil structure 60 has a first helical shape. The first helical shape is helical. The first helical shape has a substantially circular space inside. The second helical coil structure 70 has a second helical shape. The second helical shape has the same shape as the first helical shape. The second helical shape is a shape that is nested with the first helical shape. The first helical shape and the second helical shape may be in a point-symmetrical relationship with the center (center of the helix) 14a of the plasma generation device 14 as the center of symmetry.

[0049] The first helical coil structure 60 has a first inner monopole antenna 61 and a first outer monopole antenna 62. The first helical shape is formed by the first inner monopole antenna 61 and the first outer monopole antenna 62. The first inner monopole antenna 61 and the first outer monopole antenna 62 may be on the same helix. The first inner monopole antenna 61 and the first outer monopole antenna 62 are linear conductors. The first inner monopole antenna 61 is arranged along the first helical shape. The first inner monopole antenna 61 forms the inside of the first helical shape. The first outer monopole antenna 62 is spaced apart from the first inner monopole antenna 61 and arranged along the first helical shape. The first outer monopole antenna 62 forms the outside of the first helical shape. The first inner monopole antenna 61 and the first outer monopole antenna 62 may each have a length of 360° or more in the helical direction. The first inner monopole antenna 61 may have a length of 720° or less in the helical direction. The first outer monopole antenna 62 may have a length of 540° or less in the helical direction. The helical direction refers to the direction from the inner end (hereinafter referred to as the "inner end") to the outer end (hereinafter referred to as the "outer end") or the reverse direction in a certain helix or a part thereof.

[0050] The second helical coil structure 70 includes a second inner monopole antenna 71 and a second outer monopole antenna 72. The second helical shape is formed by the second inner monopole antenna 71 and the second outer monopole antenna 72. The second inner monopole antenna 71 and the second outer monopole antenna 72 may be on the same helix. The second inner monopole antenna 71 and the second outer monopole antenna 72 are linear conductors. The second inner monopole antenna 71 is arranged along the second helical shape. The second inner monopole antenna 71 forms the inside of the second helical shape. The second outer monopole antenna 72 is spaced apart from the second inner monopole antenna 71 and arranged along the second helical shape. The second outer monopole antenna 72 forms the outside of the second helical shape. The second inner monopole antenna 71 and the second outer monopole antenna 72 may each have a length of 360° or more in the helical direction. The second inner monopole antenna 71 may have a length of 720° or less in the helical direction. The second outer monopole antenna 72 may have a length of 540° or less in the helical direction.

[0051] As shown in region 300 of Figure 3A, the first coil segment 60a included in the first helical coil structure 60 and the second coil segment 70a included in the second helical coil structure 70 are arranged adjacent to each other. The first coil segment 60a and the second coil segment 70a may be adjacent to each other along the helical direction extending outward from the center 14a. The distance between adjacent first coil segments 60a and second coil segments 70a may be constant.

[0052] The first inner monopole antenna 61 has a first terminal 61a and a second terminal 61b. The first terminal 61a and the second terminal 61b may be located at either end of the first inner monopole antenna 61. The first terminal 61a is an open end. The second terminal 61b is located outside the first terminal 61a. The first terminal 61a may be located at the inner end of the first inner monopole antenna 61, and the second terminal 61b may be located at the outer end of the first inner monopole antenna 61.

[0053] The first outer monopole antenna 62 has a third terminal 62a and a fourth terminal 62b. The third terminal 62a and the fourth terminal 62b may be located at either end of the first outer monopole antenna 62. The third terminal 62a is an open end. The fourth terminal 62b is located inward from the third terminal 62a. The third terminal 62a may be located at the outer end of the first outer monopole antenna 62, and the fourth terminal 62b may be located at the inner end of the first outer monopole antenna 62. The fourth terminal 62b may be located near the second terminal 61b. The fourth terminal 62b may be located near the second terminal 61b along the spiral direction.

[0054] The second inner monopole antenna 71 has a fifth terminal 71a and a sixth terminal 71b. The fifth terminal 71a and the sixth terminal 71b may be located at either end of the second inner monopole antenna 71. The fifth terminal 71a is an open end. The sixth terminal 71b is located outside the fifth terminal 71a. The fifth terminal 71a may be located at the inner end of the second inner monopole antenna 71, and the sixth terminal 71b may be located at the outer end of the second inner monopole antenna 71.

[0055] The second outer monopole antenna 72 has a seventh terminal 72a and an eighth terminal 72b. The seventh terminal 72a and the eighth terminal 72b may be located at either end of the second outer monopole antenna 72. The seventh terminal 72a is an open end. The eighth terminal 72b is located inward from the seventh terminal 72a. The seventh terminal 72a may be located at the outer end of the second outer monopole antenna 72, and the eighth terminal 72b may be located at the inner end of the second outer monopole antenna 72. The eighth terminal 72b may be located near the sixth terminal 71b. The eighth terminal 72b may be located near the sixth terminal 71b along the spiral direction.

[0056] On the same plane, the first terminal 61a and the fifth terminal 71a are positioned opposite each other at a position 180 degrees spirally offset from the center 14a of the plasma generator 14, and are arranged so that their distances from the center 14a are equal. The second terminal 61b and the sixth terminal 71b are positioned opposite each other at a position 180 degrees spirally offset from the center 14a, and are arranged so that their distances from the center 14a are equal. The third terminal 62a and the seventh terminal 72a are positioned opposite each other at a position 180 degrees spirally offset from the center 14a, and are arranged so that their distances from the center 14a are equal. The fourth terminal 62b and the eighth terminal 72b are positioned opposite each other at a position 180 degrees spirally offset from the center 14a, and are arranged so that their distances from the center 14a are equal.

[0057] Figure 3B is a diagram illustrating an example of the electrical connection state of the plasma generator 14 shown in Figure 3A. As shown in Figure 3B, in one embodiment, the fourth terminal 62b and the eighth terminal 72b are electrically connected to a common power supply (RF power supply) 31. In one embodiment, the power supply 31 may be a variable frequency power supply. The currents flowing through the fourth terminal 62b and the eighth terminal 72b are in phase with each other. The second terminal 61b and the sixth terminal 71b are electrically connected to ground potential. When current is supplied to the first outer monopole antenna 62 and the second outer monopole antenna 72, induced currents are generated in the first inner monopole antenna 61 and the second inner monopole antenna 71. As shown in Figure 3A, the direction of the currents flowing through the first coil segment 60a and the second coil segment 70a is the same direction D1 with respect to each other. As shown in Figure 3B, in one embodiment, the fourth terminal 62b and the eighth terminal 72b may be connected to the power supply 31 via a divider (current distribution controller) 35 and an impedance matching device 36 in that order. The divider 35 is configured to equally distribute the current flowing through the fourth terminal 62b and the eighth terminal 72b. This can suppress the bias in the amount of current flowing through the first outer monopole antenna 62 and the second outer monopole antenna 72, respectively. As a result, the uniformity of the magnetic field generated by the plasma generator 14 can be improved.

[0058] The first inner monopole antenna 61, the first outer monopole antenna 62, the second inner monopole antenna 71, and the second outer monopole antenna 72 each propagate electromagnetic waves when an electric current is supplied to them. Each of the first inner monopole antenna 61, the first outer monopole antenna 62, the second inner monopole antenna 71, and the second outer monopole antenna 72 is configured to have a length equal to one-quarter wavelength of the electromagnetic wave propagating through the antenna.

[0059] In one embodiment, the second terminal 61b and the sixth terminal 71b may be electrically connected to a common power supply 31 instead of the fourth terminal 62b and the eighth terminal 72b. Thus, one of the second terminal 61b and the fourth terminal 62b and one of the sixth terminal 71b and the eighth terminal 72b may be electrically connected to a common power supply 31. The current flowing through one of the second terminal 61b and the fourth terminal 62b and the current flowing through one of the sixth terminal 71b and the eighth terminal 72b may be in phase with each other. Furthermore, the other of the second terminal 61b and the fourth terminal 62b and the other of the sixth terminal 71b and the eighth terminal 72b may be electrically connected to ground potential.

[0060] According to this exemplary embodiment, the plasma generator 14 comprises a first helical coil structure 60 having a first inner monopole antenna 61 and a first outer monopole antenna 62, and a second helical coil structure 70 having a second inner monopole antenna 71 and a second outer monopole antenna 72. With this configuration, a highly uniform magnetic field can be supplied to the plasma processing space 10s. As a result, the density of the plasma generated in the plasma processing space 10s can be made uniform.

[0061] <Modified Plasma Generator> Next, modified plasma generators 14 will be described using Figures 4-7C.

[0062] Figure 4 is a plan view showing a modified example of the plasma generation apparatus 14. As shown in Figure 4, in one embodiment, the plasma generation apparatus 14 may further include a second spiral set 80 consisting of four monopole antennas 81, 82, 83, and 84, in addition to a spiral set consisting of four monopole antennas 61, 62, 71, and 72 (a first spiral coil structure 60 and a second spiral coil structure 70) (hereinafter also referred to as the "first spiral set"). The second spiral set 80 is arranged on the same plane as the first spiral set. The second spiral set 80 has a spiral shape that is nested with the first spiral shape and the second spiral shape. The second spiral set 80 may be arranged offset by 90 degrees in the spiral direction from the first spiral set with respect to the center 14a of the spiral. The second spiral set 80 consists of a third helical coil structure 80a comprising two monopole antennas 81 and 82 from among four monopole antennas 81, 82, 83, and 84, and a fourth helical coil structure 80b comprising two monopole antennas 83 and 84. The third helical coil structure 80a may be the same configuration as one of the first helical coil structure 60 and the second helical coil structure 70. The fourth helical coil structure 80b may be the same configuration as the other of the first helical coil structure 60 and the second helical coil structure 70. In other embodiments, the plasma generator 14 may have N (N is 3 or more) spiral sets. The N spiral sets may be arranged at equal intervals from each other in the helical direction with respect to the center 14a of the spiral. For example, the N spiral sets may be arranged offset from each other by an angle of 180 degrees / N in the helical direction with respect to the center 14a.

[0063] Figure 5A is a plan view showing a modified example of the plasma generation apparatus 14. Figure 5B is a diagram illustrating an example of the electrical connection state of the plasma generation apparatus 14 shown in Figure 5A. As shown in Figures 5A and 5B, in one embodiment, the second terminal 61b, the fourth terminal 62b, the sixth terminal 71b, and the eighth terminal 72b may be electrically connected to a common power supply (RF power supply) 31 via a balun transformer 37. In one embodiment, the power supply 31 may be a variable frequency power supply. The balun transformer 37 is configured to allow the same magnitude of current to flow through the second terminal 61b, the fourth terminal 62b, the sixth terminal 71b, and the eighth terminal 72b. Furthermore, the currents flowing through the second terminal 61b and the fourth terminal 62b and the currents flowing through the sixth terminal 71b and the eighth terminal 72b are in opposite phases to each other. This suppresses the bias in the amount of current flowing through the first helical coil structure 60 and the second helical coil structure 70, respectively. As a result, the uniformity of the magnetic field generated by the plasma generator 14 can be improved.

[0064] Figure 6A is a plan view showing a modified example of the plasma generator 14. As shown in Figure 6A, in one embodiment, the plasma generator 14 may further include a drive coil structure 90 configured to be inductively coupled to the first helical coil structure 60 and the second helical coil structure 70. The drive coil structure 90 may be arranged on the same plane as the first helical coil structure 60 and the second helical coil structure 70. The drive coil structure 90 may be helical. The helical shape of the drive coil structure 90 may have a substantially circular space inside. The drive coil structure 90 includes a first drive coil 91 and a second drive coil 92. The helical shape of the drive coil structure 90 is formed by the first drive coil 91 and the second drive coil 92. The second drive coil 92 is arranged to be nested with the first drive coil 91. The shapes of the first drive coil 91 and the second drive coil 92 may be point-symmetric with respect to the center 14a of the plasma generator 14 as the center of symmetry. As shown in region 310, the first drive coil segment 91a included in the first drive coil 91 and the second drive coil segment 92a included in the second drive coil 92 are arranged adjacent to each other. The first drive coil segment 91a and the second drive coil segment 92a may be adjacent along a spiral direction extending outward from the center 14a. The distance between adjacent first drive coil segments 91a and second drive coil segments 92a may be constant. In other embodiments, the drive coil structure 90 may be arranged in any position and shape in the plasma processing apparatus 1.

[0065] Figure 6B is a diagram illustrating an example of the electrical connection state of the plasma generator 14 shown in Figure 6A. As shown in Figure 6B, the drive coil structure 90 is electrically connected to the power supply (RF power supply) 31. The first drive coil 91 and the second drive coil 92 are electrically connected to the power supply 31. The first drive coil 91 may have a first coil terminal 95 and a second coil terminal 96. The first coil terminal 95 is positioned inside the second coil terminal 96 (see Figure 6A). The first coil terminal 95 and the second coil terminal 96 may each be positioned at either end of the first drive coil 91. The first coil terminal 95 is configured to be electrically connected to the power supply 31. The second coil terminal 96 may be connected to ground potential. The second drive coil 92 may have a third coil terminal 97 and a fourth coil terminal 98. The third coil terminal 97 is positioned inward from the fourth coil terminal 98 (see Figure 6A). The third coil terminal 97 and the fourth coil terminal 98 may each be positioned on either end of the second drive coil 92. The third coil terminal 97 is configured to be electrically connected to the power supply 31, and the fourth coil terminal 98 may be connected to ground potential. In one embodiment, the first coil terminal 95 and the third coil terminal 97 may be connected to the power supply 31 via a divider 35 and an impedance matcher 36 in that order. The second coil terminal 96 and the fourth coil terminal 98 may each be connected to ground potential via a capacitor C1. In one embodiment, the power supply 31 may be a variable frequency power supply.

[0066] As shown in Figures 6A and 6B, the drive coil structure 90 is supplied with current by the power supply 31. This generates induced currents of the same magnitude in the first helical coil structure 60 and the second helical coil structure 70. The magnitude of the induced currents in the first helical coil structure 60 and the second helical coil structure 70 depends on the magnitude of the current flowing through the drive coil structure 90. The direction of the currents flowing through the first drive coil segment 91a and the second drive coil segment 92a is the same direction D2. Direction D2 may be the same direction as direction D1. The second terminal 61b, the fourth terminal 62b, the sixth terminal 71b, and the eighth terminal 72b may be electrically connected to a variable capacitor C2 (see Figure 6B). The variable capacitor C2 is configured to control the magnitude of the currents flowing through the first inner monopole antenna 61, the first outer monopole antenna 62, the second inner monopole antenna 71, and the second outer monopole antenna 72. This allows adjustment of the magnitude of the induced current generated in the first helical coil structure 60 and the second helical coil structure 70 (as a ratio to the current flowing through the drive coil structure 90).

[0067] Figures 7A to 7C are plan views showing modified examples of the plasma generator 14. As shown in Figures 7A to 7C, the distance between the second terminal 61b and the fourth terminal 62b may be arbitrarily set along the first helical shape. By changing the distance between the second terminal 61b and the fourth terminal 62b, the uniformity of the magnetic field generated by the plasma generator 14 can be adjusted. As shown in Figure 7A, the second terminal 61b and the fourth terminal 62b may be arranged to form an acute angle R1 with respect to the center 14a. As shown in Figure 7B, the second terminal 61b and the fourth terminal 62b may be further spaced apart. In Figure 7B, the second terminal 61b and the fourth terminal 62b are arranged to form a right angle R2 with respect to the center 14a. As shown in Figure 7C, the second terminal 61b and the fourth terminal 62b may be further spaced apart. In Figure 7C, the second terminal 61b and the fourth terminal 62b are spaced apart so as to be rotated by more than 360 degrees with respect to the center 14a.

[0068] The distance between the sixth terminal 71b and the eighth terminal 72b may be arbitrarily set along the second helical shape. By changing the distance between the sixth terminal 71b and the eighth terminal 72b, the uniformity of the magnetic field generated by the plasma generator 14 can be adjusted. Similar to the second terminal 61b and the fourth terminal 62b, the sixth terminal 71b and the eighth terminal 72b may be positioned at any angle with respect to the center 14a. As shown in Figure 7C, the second terminal 61b, the fourth terminal 62b, the sixth terminal 71b, and the eighth terminal 72b may be positioned on a virtual line 100 extending outward from the center 14a of the helix.

[0069] As described above, the plasma generating apparatus 14 according to this embodiment is a first helical coil structure 60 having a first helical shape, the first helical coil structure 60 having a first inner monopole antenna 61 arranged along the first helical shape, and a first outer monopole antenna 62 spaced apart from the first inner monopole antenna 61 and arranged along the first helical shape, the first inner monopole antenna 61 having a first terminal 61a which is an open end and a second terminal 61b which is arranged outside the first terminal 61a, and the first outer monopole antenna 62 having a third terminal 62a which is an open end and a fourth terminal 62b which is arranged inside the third terminal 62a, the first helical coil structure 60 and the second helical coil structure 60 having a second helical shape The second helical coil structure 70 comprises a second helical coil structure 70 arranged to be nested on the same plane as the first helical coil structure 60, the second helical coil structure 70 having a second inner monopole antenna 71 arranged along the second helical shape, and a second outer monopole antenna 72 spaced apart from the second inner monopole antenna 71 and arranged along the second helical shape, the second inner monopole antenna 71 having a fifth terminal 71a which is an open end and a sixth terminal 71b which is located outside the fifth terminal 71a, and the second outer monopole antenna 72 having a seventh terminal 72a which is an open end and an eighth terminal 72b which is located inside the seventh terminal 72a.

[0070] The embodiments described above are provided to facilitate understanding of this disclosure and are not intended to limit it. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, and sizes, are not limited to those exemplified and can be modified as appropriate. Furthermore, configurations shown in different embodiments can be partially substituted or combined.

[0071] Embodiments of this disclosure further include the following embodiments:

[0072] (Note 1) A first helical coil structure having a first helical shape, the first helical coil structure comprising a first inner monopole antenna arranged along the first helical shape, and a first outer monopole antenna spaced apart from the first inner monopole antenna and arranged along the first helical shape, wherein the first inner monopole antenna has a first terminal which is an open end and a second terminal which is located outside the first terminal, and the first outer monopole antenna has a third terminal which is an open end and a fourth terminal which is located inside the third terminal, A plasma generating apparatus comprising: a second helical coil structure having a second helical shape, wherein the second helical coil structure is arranged to be nested on the same plane as the first helical coil structure, and the second helical coil structure includes a second inner monopole antenna arranged along the second helical shape and a second outer monopole antenna spaced apart from the second inner monopole antenna and arranged along the second helical shape, wherein the second inner monopole antenna has a fifth terminal which is an open end and a sixth terminal which is located outside the fifth terminal, and the second outer monopole antenna has a seventh terminal which is an open end and an eighth terminal which is located inside the seventh terminal.

[0073] (Note 2) The plasma generation apparatus according to Note 1, wherein each of the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna has a length equal to one-quarter wavelength of the electromagnetic wave propagating through the antenna.

[0074] (Note 3) The plasma generating apparatus according to Note 2, wherein the first coil segment included in the first helical coil structure and the second coil segment included in the second helical coil structure are arranged adjacent to each other, and the currents flowing through the first coil segment and the second coil segment are in the same direction.

[0075] (Note 4) The plasma generating apparatus according to Note 3, wherein, on the same plane, the first terminal and the fifth terminal are positioned opposite each other at positions shifted 180 degrees in the spiral direction with respect to the center of the spiral, and are arranged such that their distances from the center are equal; the second terminal and the sixth terminal are positioned opposite each other at positions shifted 180 degrees in the spiral direction with respect to the center, and are arranged such that their distances from the center are equal; the third terminal and the seventh terminal are positioned opposite each other at positions shifted 180 degrees in the spiral direction with respect to the center, and are arranged such that their distances from the center are equal; and the fourth terminal and the eighth terminal are positioned opposite each other at positions shifted 180 degrees in the spiral direction with respect to the center, and are arranged such that their distances from the center are equal.

[0076] (Note 5) A plasma generating apparatus according to any one of Notes 1 to 4, wherein one of the second terminal and the fourth terminal and one of the sixth terminal and the eighth terminal are electrically connected to a common RF power supply, and the current flowing through one of the second terminal and the fourth terminal and the current flowing through one of the sixth terminal and the eighth terminal are in phase with each other.

[0077] (Note 6) The plasma generating apparatus according to Note 5, wherein the other of the second terminal and the fourth terminal and the other of the sixth terminal and the eighth terminal are electrically connected to the ground potential.

[0078] (Note 7) The plasma generation apparatus described in Note 5 or 6, wherein the common RF power supply is a variable frequency power supply.

[0079] (Note 8) The plasma generation apparatus according to any one of Notes 1 to 4, wherein the fourth terminal and the eighth terminal are electrically connected to a common RF power supply, and the currents flowing through the fourth terminal and the eighth terminal are in phase with each other.

[0080] (Note 9) The plasma generating apparatus described in Note 8, wherein the second terminal and the sixth terminal are electrically connected to the ground potential.

[0081] (Note 10) The plasma generation apparatus according to Note 8 or 9, wherein the common RF power supply is a frequency-variable power supply.

[0082] (Note 11) A plasma generating apparatus according to any one of Notes 1 to 10, comprising two or more spiral sets each consisting of four monopole antennas: the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna.

[0083] (Note 12) The plasma generation apparatus according to any one of Notes 1 to 4, wherein the second terminal, the fourth terminal, the sixth terminal and the eighth terminal are electrically connected to a common RF power supply via a balun transformer, and the currents flowing through the second terminal and the sixth terminal and the currents flowing through the fourth terminal and the eighth terminal are in opposite phase to each other.

[0084] (Note 13) The plasma generation apparatus described in Note 12, wherein the common RF power supply is a variable frequency power supply.

[0085] (Note 14) The plasma generation apparatus according to Note 1, further comprising a drive coil structure electrically connected to an RF power supply and configured to inductively couple with the first helical coil structure and the second helical coil structure, wherein the second terminal, the fourth terminal, the sixth terminal and the eighth terminal are electrically connected to a variable capacitor.

[0086] (Note 15) The plasma generation apparatus according to Note 14, wherein the drive coil structure comprises a first drive coil electrically connected to the RF power supply, and a second drive coil electrically connected to the RF power supply and arranged to be nested with the first drive coil, wherein a first drive coil segment included in the first drive coil and a second drive coil segment included in the second drive coil are arranged adjacent to each other, and the direction of the current flowing through the first drive coil segment and the second drive coil segment is the same direction to each other.

[0087] (Note 16) A first helical coil structure having a first inner monopole antenna and a first outer monopole antenna spaced apart from the first inner monopole antenna, wherein the first inner monopole antenna has a first terminal which is an open end and a second terminal which is located outside the first terminal, and the first outer monopole antenna has a third terminal which is an open end and a fourth terminal which is located inside the third terminal, A plasma generating apparatus comprising: a second helical coil structure arranged to be nested on the same plane as the first helical coil structure, the second helical coil structure having a second inner monopole antenna and a second outer monopole antenna spaced apart from the second inner monopole antenna, the second inner monopole antenna having a fifth terminal which is an open end and a sixth terminal which is located outside the fifth terminal, and the second outer monopole antenna having a seventh terminal which is an open end and an eighth terminal which is located inside the seventh terminal.

[0088] (Note 17) The plasma generation apparatus according to Note 16, wherein each of the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna has a length of one-quarter wavelength of the electromagnetic wave propagating through the antenna.

[0089] (Note 18) The plasma generating apparatus according to Note 17, wherein the first coil segment included in the first helical coil structure and the second coil segment included in the second helical coil structure are arranged adjacent to each other, and the direction of the current flowing through the first coil segment and the second coil segment is the same direction to each other.

[0090] (Note 19) The plasma generating apparatus according to Note 18, wherein, on the same plane, the second terminal, the fourth terminal, the sixth terminal, and the eighth terminal are arranged on a virtual straight line extending radially outward from the center of the helix.

[0091] (Note 20) The plasma generating apparatus according to Note 19, wherein, on the same plane, the first terminal and the fifth terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center; the second terminal and the sixth terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center; the third terminal and the seventh terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center; and the fourth terminal and the eighth terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center.

[0092] 1...Plasma processing apparatus, 2...Control unit, 2a...Computer, 2a1...Processing unit, 2a2...Storage unit, 2a3...Communication interface, 10...Plasma processing chamber, 10e...Gas outlet, 10s...Plasma processing space, 11...Substrate support unit, 12...Plasma generation unit, 13...Central gas injection unit, 13a...Gas supply port, 13b...Gas flow path, 13c...Gas inlet, 14...Antenna, Plasma generation device, 14a...Center, 20...Gas supply unit, 21...Gas source, 22...Flow rate controller, 30...Power supply system, 31...Power supply, 31 a...First RF generation unit, 31b...Second RF generation unit, 32...Power supply, 32a...Voltage generation unit, 35...Divider, 36...Impedance matching unit, 37...Balun transformer, 40...Exhaust system, 60...First helical coil structure, 60a...First coil segment, 61...First inner monopole antenna, 61a...First terminal, 61b...Second terminal, 62...First outer monopole antenna, 62a...Third terminal, 62b...Fourth terminal, 70...Second helical coil structure, 70a...Second coil segment, 71 ...Second inner monopole antenna, 71a...Fifth terminal, 71b...Sixth terminal, 72...Monopole antenna, 72a...Seventh terminal, 72b...Eighth terminal, 80...Second spiral set, 80a...Third spiral coil structure, 80b...Fourth spiral coil structure, 81, 82, 83, 84...Monopole antenna, 90...Drive coil structure, 91...First drive coil, 91a...First drive coil segment, 92...Second drive coil, 92a...Second drive coil segment, 95... 1...coil terminal, 96...2nd coil terminal, 97...3rd coil terminal, 98...4th coil terminal, 100...straight line, 101...dielectric window, 102...side wall, 111...main body, 111a...central region, 111b...annular region, 112...ring assembly, 300, 310...regions, 1110...base, 1110a...flow channel, 1111...electrostatic chuck, 1111a...ceramic member, 1111b...electrostatic chuck electrode, C1...capacitor, C2...variable capacitor, D1...direction, D2...direction, R1...acute angle, R2...right angle, W...substrate

Claims

1. A first helical coil structure having a first helical shape, the first helical coil structure comprising: a first inner monopole antenna arranged along the first helical shape; and a first outer monopole antenna spaced apart from the first inner monopole antenna and arranged along the first helical shape, wherein the first inner monopole antenna has a first terminal which is an open end and a second terminal which is located outside the first terminal; and the first outer monopole antenna has a third terminal which is an open end and a fourth terminal which is located inside the third terminal, A plasma generating apparatus comprising: a second helical coil structure having a second helical shape, wherein the second helical coil structure is arranged to be nested on the same plane as the first helical coil structure, and the second helical coil structure includes a second inner monopole antenna arranged along the second helical shape and a second outer monopole antenna spaced apart from the second inner monopole antenna and arranged along the second helical shape, wherein the second inner monopole antenna has a fifth terminal which is an open end and a sixth terminal which is located outside the fifth terminal, and the second outer monopole antenna has a seventh terminal which is an open end and an eighth terminal which is located inside the seventh terminal.

2. The plasma generation apparatus according to claim 1, wherein each of the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna has a length equal to one-quarter wavelength of the electromagnetic wave propagating through the antenna.

3. The plasma generating apparatus according to claim 2, wherein the first coil segment included in the first helical coil structure and the second coil segment included in the second helical coil structure are arranged adjacent to each other, and the currents flowing through the first coil segment and the second coil segment are in the same direction.

4. The plasma generating apparatus according to claim 3, wherein, on the same plane, the first terminal and the fifth terminal are positioned opposite each other at positions offset 180 degrees in the spiral direction with respect to the center of the spiral, and are arranged such that their distances from the center are equal; the second terminal and the sixth terminal are positioned opposite each other at positions offset 180 degrees in the spiral direction with respect to the center, and are arranged such that their distances from the center are equal; the third terminal and the seventh terminal are positioned opposite each other at positions offset 180 degrees in the spiral direction with respect to the center, and are arranged such that their distances from the center are equal; and the fourth terminal and the eighth terminal are positioned opposite each other at positions offset 180 degrees in the spiral direction with respect to the center, and are arranged such that their distances from the center are equal.

5. The plasma generation apparatus according to any one of claims 1 to 4, wherein one of the second terminal and the fourth terminal and one of the sixth terminal and the eighth terminal are electrically connected to a common RF power supply, and the current flowing through one of the second terminal and the fourth terminal and the current flowing through one of the sixth terminal and the eighth terminal are in phase with each other.

6. The plasma generating apparatus according to claim 5, wherein the other of the second terminal and the fourth terminal and the other of the sixth terminal and the eighth terminal are electrically connected to the ground potential.

7. The plasma generation apparatus according to claim 5, wherein the common RF power supply is a frequency-variable power supply.

8. The plasma generation apparatus according to any one of claims 1 to 4, wherein the fourth terminal and the eighth terminal are electrically connected to a common RF power supply, and the currents flowing through the fourth terminal and the eighth terminal are in phase with respect to each other.

9. The plasma generating apparatus according to claim 8, wherein the second terminal and the sixth terminal are electrically connected to the ground potential.

10. The plasma generation apparatus according to claim 8, wherein the common RF power supply is a frequency-variable power supply.

11. The plasma generation apparatus according to claim 1, comprising two or more spiral sets, each set comprising four monopole antennas, the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna.

12. The plasma generation apparatus according to any one of claims 1 to 4, wherein the second terminal, the fourth terminal, the sixth terminal and the eighth terminal are electrically connected to a common RF power supply via a balun transformer, and the currents flowing through the second terminal and the sixth terminal and the currents flowing through the fourth terminal and the eighth terminal are in opposite phase to each other.

13. The plasma generation apparatus according to claim 12, wherein the common RF power supply is a frequency-variable power supply.

14. The plasma generation apparatus according to claim 1, further comprising a drive coil structure electrically connected to an RF power supply and configured to inductively couple with the first helical coil structure and the second helical coil structure, wherein the second terminal, the fourth terminal, the sixth terminal and the eighth terminal are electrically connected to a variable capacitor.

15. The plasma generation apparatus according to claim 14, wherein the drive coil structure comprises a first drive coil electrically connected to the RF power supply, and a second drive coil electrically connected to the RF power supply and arranged to be nested with the first drive coil, wherein a first drive coil segment included in the first drive coil and a second drive coil segment included in the second drive coil are arranged adjacent to each other, and the direction of the current flowing through the first drive coil segment and the second drive coil segment is the same direction to each other.

16. A first helical coil structure comprising a first inner monopole antenna and a first outer monopole antenna spaced apart from the first inner monopole antenna, wherein the first inner monopole antenna has a first terminal which is an open end and a second terminal which is located outside the first terminal, and the first outer monopole antenna has a third terminal which is an open end and a fourth terminal which is located inside the third terminal, A plasma generating apparatus comprising: a second helical coil structure arranged to be nested on the same plane as the first helical coil structure, the second helical coil structure having a second inner monopole antenna and a second outer monopole antenna spaced apart from the second inner monopole antenna, the second inner monopole antenna having a fifth terminal which is an open end and a sixth terminal which is located outside the fifth terminal, and the second outer monopole antenna having a seventh terminal which is an open end and an eighth terminal which is located inside the seventh terminal.

17. The plasma generating apparatus according to claim 16, wherein each of the first inner monopole antenna, the first outer monopole antenna, the second inner monopole antenna, and the second outer monopole antenna has a length equal to one-quarter wavelength of the electromagnetic wave propagating through the antenna.

18. The plasma generating apparatus according to claim 17, wherein the first coil segment included in the first helical coil structure and the second coil segment included in the second helical coil structure are arranged adjacent to each other, and the direction of the current flowing through the first coil segment and the second coil segment is the same direction to each other.

19. The plasma generating apparatus according to claim 18, wherein, on the same plane, the second terminal, the fourth terminal, the sixth terminal, and the eighth terminal are arranged on a virtual straight line extending radially outward from the center of the helix.

20. The plasma generating apparatus according to claim 19, wherein, on the same plane, the first terminal and the fifth terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center; the second terminal and the sixth terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center; the third terminal and the seventh terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center; and the fourth terminal and the eighth terminal are positioned opposite each other at positions shifted 180 degrees spirally with respect to the center and are arranged to be at equal distances from the center.

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