Filter circuit and plasma processor

Abstract

To provide a filter circuit and a plasma processor which can realize a simple and compact high-frequency filter.SOLUTION: The filter circuit includes a housing, a protrusion unit, and a power supply line. The housing is formed of a conductor and has an input port and an output port formed of an external conductor and an internal conductor. The housing is configured so that the potential of the housing and the potentials of the external conductors of the input port and the output port are ground potentials. The protrusion unit is formed of a conductor, is connected to the housing, and protrudes spirally in the housing. The power supply line is provided in the housing and is insulated from the housing. The power supply line has an input-side conductor as an internal conductor of the input port, an output-side conductor as an internal conductor of the output port, and an antenna connected to the input-side conductor and the output-side conductor and formed in a spiral pattern coaxial with the protrusion unit. The protrusion unit and the antenna have a choke structure.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a filter circuit and a plasma processing apparatus.

Background Art

[0002] The plasma processing apparatus disclosed in Patent Document 1 includes a processing container in which plasma processing is performed, a mounting table that is disposed via a space on a plate-shaped conductive base in the processing container and mounts and holds a substrate to be processed, a high-frequency electrode provided on the mounting table, a high-frequency power supply unit for applying a high-frequency wave of a constant frequency to the high-frequency electrode, a heating element provided on the mounting table, a heater power supply line for electrically connecting the heating element to a heater power supply disposed outside the processing container, a coil for attenuating or blocking high-frequency noise entering the heater power supply line via the heating element, and a casing that houses this coil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a filter circuit and a plasma processing apparatus that can realize a simple and compact high-frequency filter.

Means for Solving the Problems

[0005] A filter circuit according to one aspect of the present disclosure includes a housing, a protruding portion, and a power supply line. The housing is formed of a conductor and includes an input port and an output port formed of an outer conductor and an inner conductor, and is configured to have a ground potential together with the outer conductors of the input port and the output port. The protruding portion is formed of a conductor, is connected to the housing, and is configured to protrude spirally into the housing. The power supply line is provided in the housing and is insulated from the housing. Further, the power supply line is connected to an input-side conductor that is the inner conductor of the input port, an output-side conductor that is the inner conductor of the output port, and an antenna formed in a spiral coaxial with the protruding portion. The protruding portion and the antenna form a choke structure.

Advantages of the Invention

[0006] According to the present disclosure, a simple and compact high-frequency filter can be realized.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the disclosed filter circuit and plasma processing apparatus will be described in detail with reference to the drawings. Note that the disclosed technology is not limited by the following embodiments.

[0009] In a plasma processing apparatus, a power supply disposed outside the processing chamber is connected to an electrostatic chuck or a heater provided in a substrate support unit that supports a substrate to be processed. Since the substrate support unit constitutes a lower electrode for generating plasma, high-frequency power for plasma generation may affect the power supply lines to the electrostatic chuck and the heater. For this reason, a high-frequency filter composed of a coil and a capacitor is inserted into these power supply lines. However, a high-frequency filter composed of a coil and a capacitor has a complicated structure and large dimensions. Therefore, it is expected to realize a simple and compact high-frequency filter.

[0010] [Configuration of Plasma Processing System] A configuration example of a plasma processing system will be described below. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus according to an embodiment of the present disclosure. As shown in FIG. 1, the plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a control unit 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power source 30, an exhaust system 40, a DC power source 45, and a filter circuit 50. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a showerhead 13. The substrate support unit 11 is disposed in the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support unit 11. In one embodiment, the showerhead 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas discharge port for discharging gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support unit 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] 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. The wafer is an example of the 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 disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed 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. Accordingly, the central region 111a is also referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as a ring support surface for supporting the ring assembly 112.

[0012] In one embodiment, the main body portion 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 lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. The electrostatic electrode 1111b is connected to a DC power supply 45 via a filter circuit 50. When a voltage from the DC power supply 45 is applied to the electrostatic electrode 1111b, an electrostatic attraction force is generated between the electrostatic chuck 1111 and the substrate W. Due to the generated electrostatic attraction force, the substrate W is attracted to the electrostatic chuck 1111 and held by the electrostatic chuck 1111.

[0013] Further, at least one RF / DC electrode coupled to an RF (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be described later, is supplied to at least one RF / DC electrode, the RF / DC electrode is also referred to as a bias electrode. Note that the conductive member of the base 1110 and at least one RF / DC electrode may function as a plurality of lower electrodes. Also, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0014] Further, the substrate support portion 11 may include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate W 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 disposed within the ceramic member 1111a of the electrostatic chuck 1111. Also, the substrate support portion 11 may include a heat transfer gas supply portion configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.

[0015] The showerhead 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas introduction ports 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c. Further, the showerhead 13 includes at least one upper electrode. In addition to the showerhead 13, the gas introduction part may include one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

[0016] 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 process gas from the corresponding gas source 21 to the showerhead 13 via the corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Further, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one process gas.

[0017] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. Thereby, plasma is formed from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generation unit configured to generate plasma from one or more process gases in the plasma processing chamber 10. Also, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and the ion component in the formed plasma can be drawn into the substrate W.

[0018] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 300 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0019] The second RF generation unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). 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 in 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 lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] In addition, the power supply 30 may include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and is configured to generate a first DC signal. The generated first DC signal (bias DC signal) is applied to at least one lower electrode. In one embodiment, the second DC generation unit 32b is connected to at least one upper electrode and is configured to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0021] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a pulse waveform that is rectangular, trapezoidal, triangular, or a combination thereof. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from the DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Accordingly, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have a positive polarity or a negative polarity. Also, the sequence of voltage pulses may include one or more positive-polarity voltage pulses and one or more negative-polarity voltage pulses within one period. Note that the first and second DC generation units 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generation unit 32a may be provided in place of the second RF generation unit 31b.

[0022] The exhaust system 40 can be connected to, for example, a gas outlet 10e provided 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 in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbo molecular pump, a dry pump, or a combination thereof.

[0023] The filter circuit 50 removes the influence of high-frequency power for plasma generation or bias on the DC power supply 45 when plasma is generated in the plasma processing space 10s. The filter circuit 50 allows the DC current applied from the DC power supply 45 to the electrostatic electrode 1111b to pass through and blocks the high-frequency power flowing in the reverse direction from the electrostatic electrode 1111b.

[0024] The control unit 2 processes computer-executable instructions for causing the plasma processing apparatus 1 to execute various processes described in the present disclosure. The control unit 2 can be configured to control each element of the plasma processing apparatus 1 so as to execute 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 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is realized by, for example, a computer 2a. The processing unit 2a1 can be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 and executed. The medium may be various storage media readable by the computer 2a, or may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0025] [Structure of Filter Circuit 50] Next, the details of the filter circuit 50 will be described with reference to FIGS. 2 to 4. FIG. 2 is a perspective view showing an example of the filter circuit according to the present embodiment. FIG. 3 is a cross-sectional view showing an example of the A-A cross-section of FIG. 2. As shown in FIGS. 2 and 3, the filter circuit 50 has a housing 51. The housing 51 is formed of a conductor such as aluminum or copper. The housing 51 also includes an input port 52 and an output port 55. In the present embodiment, since high-frequency power is blocked, based on the flow direction of the high-frequency power, the side connected to the electrostatic electrode 1111b will be described as the input port 52, and the side connected to the DC power supply 45 will be described as the output port 55. Note that the input port 52 and the output port 55 may be interchanged in terms of the connection destination.

[0026] The input port 52 and the output port 55 are each formed of an outer conductor 53, 56 and an inner conductor 54, 57. That is, the input port 52 and the output port 55 have a coaxial structure. The housing 51 is electrically connected to the outer conductors 53, 56 and has a ground potential together with the grounded plasma processing chamber 10 via a coaxial cable connected to the input port 52 or a frame on which the filter circuit 50 is installed. The housing 51 has a cylindrical shape, and the input port 52 is formed on the side surface 60 of the cylinder. Note that the housing 51 may have a cylindrical shape with a square cross-section. The output port 55 is formed at the end of the cylinder on the side where the input port 52 is formed, and the other end 58 is formed in a disk shape so as to close the cylinder. Further, a central protrusion 59 formed of a conductor such as aluminum or copper and protruding into the housing 51 and a spiral fin 67 centered on the central protrusion 59 are connected to the end 58. The central protrusion 59 has, for example, a cylindrical shape. The fin 67 is an example of a protrusion and is an example of a first fin connected to the base (end 58) of the protrusion.

[0027] Inside the housing 51, an antenna 65 is provided that is formed in a spiral shape coaxial with the fins 67 with the central protrusion 59 as the approximate center. The antenna 65 is formed of a conductor such as aluminum or copper, and the spiral fins formed at the base 62 of the antenna 65 are formed to be alternately intertwined with the fins 67 in the A-A cross section. That is, the antenna 65 is equivalent to a cylindrical multi-pole antenna when viewed from the electromagnetic waves of the frequency to be blocked. In other words, the antenna 65 is an antenna (coaxial insertion multi-pole antenna) that does not radiate electromagnetic waves at the frequency to be blocked. Note that the tip 65a of the antenna 65 and the tip 67a of the fins 67 tend to concentrate the electric field if they have an overly pointed shape, so it is preferable that the antenna 65 and the fins 67 have a certain thickness. Also, the closer the distance between the antenna 65 and the fins 67, the better the frequency characteristics described later. Note that the antenna 65 is an example of the second fin.

[0028] The base 62 is disk-shaped, and its central portion is convex so as to be offset toward the output port 55 side. The inner conductor 54 is connected to the side surface 63 of the base 62. The inner conductor 57 is connected to the upper surface 64 of the base 62. That is, a feeding line 61 insulated from the housing 51 is formed by the inner conductor (input side conductor) 54 of the input port 52, the inner conductor (output side conductor) 57 of the output port 55, and the antenna 65 including the base 62. That is, in the filter circuit 50, the feeding line 61 formed by the inner conductor 54, the antenna 65, and the inner conductor 57 is arranged at a right angle. Note that the feeding line 61 is a path for feeding direct current from the DC power supply 45 to the electrostatic electrode 1111b. Also, the connection portion with the inner conductor 57 on the upper surface 64 may be further convex as shown in FIG. 3.

[0029] FIG. 4 is a cross-sectional view showing an example of the B-B cross-section of FIG. 3. As shown in FIG. 4, in the interior of the housing 51, the filter circuit 50 has the antenna 65 and the fins 67 formed in a coaxial spiral shape with the central protrusion 59 as the approximate center. That is, the antenna 65 and the fins 67 are formed in a coaxial spiral shape in the B-B cross-section. In FIG. 4, the antenna 65 is represented by a dashed line on the assumption that there is a dielectric 66, which will be described later, between the B-B cross-section and the tip 65a of the antenna 65. In the example of FIG. 4, the antenna 65 has a spiral with 6 turns, and the fins 67 have a spiral with 5 turns. Note that the number of turns of the spiral is not limited to this. Also, the antenna 65 and the fins 67 can be miniaturized more as the number of turns of the spiral increases, provided they have the same resonance frequency. The antenna 65 and the fins 67 are arranged, for example, such that the respective ends on the inner and outer circumferential sides of the spiral are at positions shifted by 180 degrees from each other. Note that the angle of deviation of the respective ends on the inner circumferential side is related to the resonance frequency of the harmonic waves described later, and the angle is changed according to the resonance frequency of the harmonic waves. Also, the position of the end on the outer circumferential side of the antenna 65 does not have to be the same as the direction of the input port 52.

[0030] A dielectric 66 is provided between the housing 51 and the power supply line 61. That is, the space between the central protrusion 59, the antenna 65, and the fin 67, the space between the antenna 65 and the fin 67, the space between the antenna 65, the fin 67, and the side surface 60 of the cylinder, and the space between the tip 65a of the antenna 65 and the end 58 are filled with the dielectric 66. Since the space between the antenna 65 and the fin 67 is spiral, a state in which the dielectric 66 is easily filled can be formed by sandwiching the sheet-like dielectric 66. Similarly, the space between the outer conductor 53 and the inner conductor 54 of the input port 52 and the space between the outer conductor 56 and the inner conductor 57 of the output port 55 are also filled with the dielectric 66. As the dielectric 66, for example, PTFE (Poly Tetra Fluoro Ethylene) or the like can be used. Regarding a part of the antenna 65 located near the central protrusion 59, although it appears to float in the dielectric 66 in the A-A cross section shown in FIG. 3, it is actually connected to the base 62. Also, regarding the fin 67, it is not in a floating state but is connected to the end 58.

[0031] Also, in the antenna 65, the space between the housing 51, the fins 67, and the central protrusion 59 from the outer peripheral surface 65b of the base 62 of the antenna 65 to the central surface 65c forms a choke structure based on the length of a quarter wavelength of the electromagnetic wave to be blocked. Here, in the cross-section A-A of FIG. 3, the path from the surface 65b to the surface 65c that repeatedly bends multiple times between the antenna 65 and the fins 67 via the inner surface 58a facing the tip 65a is the transmission path length W1. That is, the transmission path length W1 forms a choke structure based on the length of a quarter wavelength of the electromagnetic wave to be blocked, a so-called λ / 4 choke. That is, since the electromagnetic wave to be blocked travels back and forth along the transmission path length W1, the antenna 65 becomes a half-wave antenna with a length twice that of the transmission path length W1. Note that the electromagnetic wave can be considered to be radiated from the entire ring-shaped surface 65b. Also, in FIG. 3, there is a portion where there are no fins 67 between the spirals of the antenna 65, but the transmission path length W1 is shown assuming that there are fins 67 for the sake of convenience. In the case where the portion without fins 67 between the spirals of the antenna 65 occupies most of the circumferential direction, the path connecting the tips 65a of the antenna 65 in that portion may be considered to be included in the transmission path length W1.

[0032] Here, the height h of the spiral antenna 65 and the fins 67 is required to be sufficiently shorter than the cutoff wavelength λc in order to function as an electromagnetic wave choke. Since the electromagnetic wave mode that can propagate in the spiral antenna 65 and the fins 67 is the TE01 mode, the cutoff wavelength λc is given by the following equation (1). Also, assuming the effective wavelength of the electromagnetic wave input to the filter circuit 50 is λin, the condition for the electromagnetic wave choke to function is given by the following equation (2).

[0033] λc = 2h ···(1) λin>>λc ···(2)

[0034] For example, consider the case where the frequency of the high-frequency power, which is the electromagnetic wave to be blocked, that is, the input electromagnetic wave, is 220 MHz, and PTFE with a relative permittivity of 2.1 is used for the dielectric 66. At this time, the effective wavelength in the dielectric 66 is λin = 941 mm. For example, in the filter circuit 50, when the height h = 16 mm, the cutoff wavelength λc = 32 mm, and it can be seen that the above formula (2) holds and it functions as an electromagnetic choke. Note that the path along the helix can also be regarded as a waveguide, but the electromagnetic wave is cut off, and the electromagnetic wave is not transmitted along the path along the helix. Also, if the electromagnetic choke functions, the number of turns of the spiral antenna 65 and the fins 67 is not limited, and the fins on the antenna 65 side and the fins on the end 58 side (fins 67 side) may each be composed of a plurality of fins.

[0035] [Simulation Results] Next, the simulation results of the electric field distribution of the filter circuit 50 will be described with reference to FIGS. 5 and 6. FIG. 5 is a diagram showing an example of the simulation results of the electric field distribution in the filter circuit according to the present embodiment. The simulation result 70 shown in FIG. 5 shows the electric field distribution when high-frequency power of 220 MHz and 1000 W is input from the input port 52. In the simulation result 70, in the transmission path length W1 from the surface 65b to the surface 65c, the space between the antenna 65 and the fin 67 has a high electric field strength. Also, the spaces between the antenna 65 and the fin 67 and the side surface 60, and between the antenna 65 and the fin 67 and the central protrusion 59 have relatively lower electric field strengths than the space between the antenna 65 and the fin 67. Further, in the vicinity of the output port 55, the electric field strength is almost zero. That is, the antenna 65 and the fin 67 in the housing 51 generate a reflected wave with a 180-degree phase shift from the traveling wave, and the traveling wave and the reflected wave cancel each other out, so that the output of the 220-MHz high-frequency power from the output port 55 becomes 0 W. Note that a part of the antenna 65 located near the central protrusion 59 appears to be floating in the cross section of FIG. 5 (corresponding to the A-A cross section of FIG. 3), but it is actually connected to the base 62. Also, the fin 67 is assumed to be connected to the end 58 instead of being in a floating state.

[0036] FIG. 6 is a graph showing an example of the frequency characteristics of the filter circuit according to the present embodiment. The graph 75 shown in FIG. 6 represents the frequency characteristics of the filter circuit 50 in terms of the S parameter S 21 as shown. In FIG. 6, the vertical axis of the graph is S 21(Insertion loss) is represented, so the attenuation amount increases more on the negative side. As shown in graph 75, the attenuation amount of the filter circuit 50 is maximum at 220 MHz, and the insertion loss is -72 dB. Also, the insertion loss in the range 76 from 170 MHz to 270 MHz is -30 dB or less. That is, the filter circuit 50 forms a band-stop filter centered at 220 MHz. Thus, in this embodiment, a high frequency of the frequency to be blocked is resonated with a three-dimensional circuit using a multi-pole antenna with spiral fins. For this reason, for example, a simple and compact high-frequency filter for high-output high-frequency power such as 1000 W in the VHF (Very High Frequency) band can be realized. Also, since the power supply line 61 is insulated from the housing 51, the output of the DC power supply 45 can be applied to the electrostatic electrode 1111b without being grounded. Further, in this embodiment, in the frequency range shown in range 76, electromagnetic waves (single-peak waveform) whose frequency is variable using FM modulation or the like, and electromagnetic waves of a plurality of frequencies (broadband waveform) generated as multi-tone can also be blocked.

[0037] [Adjustment of the number of turns of the spiral] Subsequently, the adjustment of the resonance frequency according to the number of turns of the spiral of the antenna 65 and the fins 67 will be described with reference to FIGS. 7 to 9. FIG. 7 is a diagram showing an example of the adjustment of the resonance frequency according to the winding angle of the spiral. As shown in FIG. 7, the antenna 65 has six turns of the spiral from the outer peripheral end 65d to the inner peripheral end 65e. The fin 67 has five turns of the spiral from the outer peripheral end 67b to the inner peripheral end 67c. Note that the fin 67 may have six turns of the spiral as in the case of the antenna 65. In this case, the resonance frequency can be set to 220 MHz by adjusting the dimensions of each part of the filter circuit 50.

[0038] Here, pay attention to the angular deviation in the circumferential direction with the central protrusion 59 of the central part between the inner peripheral end 65e of the antenna 65 and the inner peripheral end 67c of the fin 67 as the approximate center. For example, in FIG. 7, taking the line connecting the central protrusion 59 and the end 65e as the reference of 0 degrees, assume that the angle θ of the end 67c is changed in the clockwise direction. Also, assume that the position where the angle θ of the end 67c is 180 degrees is the initial angle θ1. Note that the angle θ also represents the winding angle of the helix. In the filter circuit 50, by changing the angle θ of the end 67c, the resonance frequency (fundamental frequency) of the filter circuit 50 and the resonance frequencies of the harmonics are changed. That is, in the filter circuit 50, the resonance frequency (fundamental frequency) and the resonance frequencies of the harmonics are determined by the difference in the circumferential length between the end 65e and the end 67c. Note that changing the angle θ of the end 67c can also be said to adjust the number of turns of one of them so that the number of turns of the antenna 65 and the fin 67 are different. That is, the number of turns includes the value after the decimal point corresponding to the angle θ. Also, the angle θ of the end 67c is structurally changed. Note that if the positions of the outer peripheral ends 65d and 67b are changed in accordance with the inner peripheral ends 65e and 67c, the resonance frequency of the reference filter circuit 50 will also shift. Therefore, it is preferable to fix the positions of the outer peripheral ends 65d and 67b.

[0039] FIG. 8 is a graph showing an example of the resonance frequency dependence of the winding angle of the helix. As shown in FIG. 8, the graph 77 shows the relationship between the fundamental frequency of the filter circuit 50 and the angle θ. The graph 78 shows the relationship between the resonance frequency of the filter circuit 50 at a frequency near the third harmonic and the angle θ. When the angle θ is the initial angle θ1 (180 degrees), from the graphs 77 and 78, the fundamental frequency is 220 MHz, and the resonance frequency near the third harmonic is 675 MHz. When the angle θ of the end 67c is changed in the direction of adding the angle θ2 to the angle θ1 in the clockwise direction, at the position 79 where the angle θ is 315 degrees, the fundamental frequency is 217 MHz, and the resonance frequency near the third harmonic is 660 MHz.

[0040] FIG. 9 is a graph showing an example of the change in resonance frequency due to the winding angle of the spiral. The graphs 80 and 82 shown in FIG. 9 respectively show the frequency characteristics of the filter circuit 50 at the angle θ1 (180 degrees) and the adjusted angle θ (315 degrees) in terms of the S parameter S 21 as represented. Also shown in FIG. 9 is the third harmonic (660 MHz) of the fundamental frequency (220 MHz) of the electromagnetic wave to be blocked as the third harmonic 81. In the graph 80, the insertion loss of the filter circuit 50 is -67 dB at 220 MHz, -23 dB at 660 MHz, and -46 dB at 675 MHz. In this case, for the third harmonic 81 (660 MHz) of the electromagnetic wave to be blocked, the insertion loss is not less than -30 dB, and the attenuation amount is not sufficient. On the other hand, in the graph 82, the insertion loss of the filter circuit 50 is -68 dB at 220 MHz and -46 dB at 660 MHz. In this case, for the third harmonic 81 (660 MHz) of the electromagnetic wave to be blocked, the insertion loss is less than -30 dB, and a sufficient attenuation amount is ensured. That is, in the filter circuit 50, by adjusting the angle θ of the end portion 67c from 180 degrees to 315 degrees, both the fundamental frequency (220 MHz) and the third harmonic (660 MHz) of the electromagnetic wave to be blocked can be simultaneously attenuated and blocked. Note that the filter circuit 50 can similarly attenuate and block odd multiples of the Nth harmonic.

[0041] [Modification Example] Next, a first modification example in which the position of the output port 55 is changed will be described. FIG. 10 is a cross-sectional view showing an example of a filter circuit according to the first modification example. The filter circuit 90 shown in FIG. 10 has the position of the output port 55a as the cylindrical side surface 60 of the housing 51a facing the input port 52. In the filter circuit 90, the same components as those in the filter circuit 50 are denoted by the same reference numerals, and the description of the overlapping components and operations will be omitted. The output port 55a is formed by an outer conductor 56a and an inner conductor 57a. In the housing 51a, the end of the cylinder on the side where the input port 52 and the output port 55a are formed is closed. The end of the cylinder corresponds to the surface where the output port 55 is formed in FIG. 2. The outer conductor 56a is electrically connected to the housing 51a. The inner conductor 57a is connected to the side surface 64a of the base 62. The side surface 64a is located opposite to the side surface 63a where the inner conductor 54 of the input port 52 is connected to the base 62. That is, in the filter circuit 90, the power supply line 61a formed by the inner conductor 54, the antenna 65, and the inner conductor 57a is arranged linearly. Regarding a part of the antenna 65 located near the central protrusion 59, although it appears to float in the dielectric 66 in the cross-section of FIG. 10, it is actually connected to the base 62. Also, regarding the fin 67, it is not in a floating state but is connected to the end 58.

[0042] FIG. 11 is a graph showing an example of the frequency characteristics of the filter circuit according to the first modification example. The graph 91 shown in FIG. 11 represents the frequency characteristics of the filter circuit 90 in terms of the S parameter of the S 21 In FIG. 11, similar to FIG. 6, the vertical axis of the graph is S 21(Insertion loss) is represented, so the attenuation amount increases as the value becomes more negative. As shown in graph 91, the attenuation amount of filter circuit 90 is maximum at 220 MHz, and the insertion loss is -68 dB. Also, the insertion loss in the range 92 from 170 MHz to 270 MHz is -30 dB or less. Thus, also in Modification 1, the high frequency of the frequency to be blocked by the three-dimensional circuit using the multi-pole antenna with spiral fins is resonated. For this reason, for example, a simple and compact high-frequency filter for high-output high-frequency power such as 1000 W in the VHF band can be realized. Also, since the power supply line 61a is insulated from the housing 51a, the output of the DC power supply 45 can be applied to the electrostatic electrode 1111b without being grounded.

[0043] In addition, in the above-described embodiment, the case where the central protrusion 59 and the fins 67 are fixed has been described, but it is not limited thereto. For example, the fins 67 may be formed so as to be insertable into and removable from the antenna 65. In this case, the fins 67 are driven by a drive mechanism (not shown), and the height h can be varied. As the drive mechanism, a combination of a stepping motor and a lead screw or the like can be used. When the fins 67 are inserted and removed and the height h is changed, the frequency blocked by the filter circuit 50 can be changed.

[0044] As described above, according to the present embodiment, the filter circuits 50 and 90 include a housing 51, 51a, a protruding portion (fin 67), and a power supply line 61, 61a. The housing 51, 51a is formed of a conductor and includes an input port 52 and an output port 55 formed by an outer conductor 53, 56 and an inner conductor 54, 57, and is configured to have a ground potential together with the outer conductors 53, 56 of the input port 52 and the output port 55. The protruding portion is formed of a conductor, is connected to the housing 51, 51a, and is configured to protrude spirally into the housing 51, 51a. The power supply lines 61, 61a are provided in the housing 51, 51a and are insulated from the housing 51, 51a. Further, the power supply lines 61, 61a are connected to an input-side conductor that is the inner conductor 54 of the input port 52, an output-side conductor that is the inner conductor 57 of the output port 55, the input-side conductor, and the output-side conductor, and are configured to include an antenna 65 formed in a spiral shape coaxial with the protruding portion. The protruding portion and the antenna 65 form a choke structure. As a result, a simple and compact high-frequency filter can be realized.

[0045] Further, according to the present embodiment, the filter circuits 50, 90 are further configured to have a dielectric 66 between the housing 51, 51a and the power supply line 61, 61a. As a result, the filter circuits 50, 90 can be miniaturized.

[0046] Further, according to the present embodiment, the input port 52 and the output port 55 have a coaxial structure. As a result, a filter circuit for high-output high-frequency power can be formed.

[0047] Further, according to the present embodiment, the choke structure is composed of a plurality of fins. The plurality of fins are alternately arranged with a first fin (fin 67) connected to the base (end portion 58) of the protruding portion and a second fin connected to the base 62 of the antenna 65. As a result, the choke structure can be easily formed.

[0048] Further, according to the present embodiment, the plurality of fins are two fins, i.e., a first fin and a second fin formed in a spiral shape. As a result, a choke structure can be formed more easily.

[0049] Further, according to the present embodiment, the space between the casings 51, 51a and the protrusion and the antenna 65 from the outer peripheral surface 65b to the central surface 65c of the base 62 of the antenna 65 forms a choke structure based on the length of a quarter wavelength of the electromagnetic wave to be blocked. As a result, high-frequency power can be blocked at the frequency to be blocked.

[0050] Further, according to the present embodiment, the protrusion and the antenna 65 adjust the number of spiral turns based on the wavelength of the electromagnetic wave to be blocked. As a result, high-frequency power can be blocked at the frequency to be blocked.

[0051] Further, according to the present embodiment, the protrusion and the antenna 65 adjust the number of turns of one of them so that the number of turns of each is different. As a result, high-frequency power can be blocked at the frequency to be blocked and the odd multiples of the harmonic waves.

[0052] Further, according to the present embodiment, it further has a drive mechanism capable of adjusting the distance between the base of the protrusion and the base 62 of the antenna 65. As a result, the frequency blocked by the filter circuits 50, 90 can be changed.

[0053] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiments may be omitted, replaced, or changed in various forms without departing from the scope and gist of the appended claims.

[0054] Also, in the above-described embodiment, the transmission path length W1 is set to a quarter wavelength of the electromagnetic wave to be blocked, but it is not limited thereto. For example, the dimensions and the number of turns of the antenna 65 and the fins 67 may be set so that the transmission path length is such that the traveling wave and the reflected wave cancel each other out.

[0055] In the above-described embodiment, the filter circuits 50 and 90 are connected to the electrostatic electrode 1111b inside the electrostatic chuck 1111, but the present invention is not limited thereto. For example, it may be connected to a heater (not shown) provided in the substrate support portion 11.

[0056] In the above-described embodiment, the plasma processing apparatus 1 that performs processing such as etching on the substrate W using capacitively coupled plasma as the plasma source has been described as an example. However, the disclosed technology is not limited thereto. As long as it is an apparatus that performs processing on the substrate W using plasma, the plasma source is not limited to capacitively coupled plasma. For example, any plasma source such as inductively coupled plasma, microwave plasma, magnetron plasma, etc. can be used.

[0057] Note that the present disclosure can also adopt the following configurations. (1) A housing formed of a conductor, having an input port and an output port formed of an outer conductor and an inner conductor, and configured to have a ground potential together with the outer conductors of the input port and the output port; A protruding portion formed of a conductor, connected to the housing, and configured to protrude spirally inside the housing; A power supply line provided inside the housing and insulated from the housing; The power supply line An input-side conductor that is the inner conductor of the input port; An output-side conductor that is the inner conductor of the output port; An antenna connected to the input-side conductor and the output-side conductor and formed in a spiral coaxial with the protruding portion; The protruding portion and the antenna form a choke structure. A filter circuit. (2) Furthermore, between the housing and the power supply line, it is configured to have a dielectric. The filter circuit according to (1) above. (3) The input port and the output port have a coaxial structure. The filter circuit according to (1) or (2) above. (4) The choke structure is composed of a plurality of fins. Among the plurality of fins, a first fin connected to the base of the protrusion and a second fin connected to the base of the antenna are alternately arranged. The filter circuit according to any one of (1) to (3) above. (5) The plurality of fins are two fins, namely, the first fin and the second fin formed in a spiral shape. The filter circuit according to (4) above. (6) The space between the housing, the protrusion and the antenna from the outer peripheral side surface to the central surface of the base of the antenna forms the choke structure based on the length of 1 / 4 wavelength of the electromagnetic wave to be blocked. The filter circuit according to any one of (1) to (5) above. (7) The protrusion and the antenna adjust the number of spiral turns based on the wavelength of the electromagnetic wave to be blocked. The filter circuit according to any one of (1) to (6) above. (8) The protrusion and the antenna adjust the number of turns of one of them so that the respective numbers of turns are different. The filter circuit according to (7) above. (9) The filter circuit further includes a drive mechanism capable of adjusting the distance between the base of the protrusion and the base of the antenna. The filter circuit according to any one of (1) to (8) above. (10) A plasma processing apparatus, The plasma processing apparatus, includes a processing container, an electrode provided in the processing container to which two or more frequencies are applied, and a filter circuit. The filter circuit is formed of a conductor, and includes an input port and an output port formed of an outer conductor and an inner conductor, and a housing configured to have a ground potential together with the outer conductors of the input port and the output port; formed of a conductor, connected to the housing, and having a protruding portion configured to protrude spirally inside the housing; and a power supply line provided inside the housing and insulated from the housing. The power supply line is an input-side conductor that is the inner conductor of the input port, is an output-side conductor that is the inner conductor of the output port, is connected to the input-side conductor and the output-side conductor, and is configured to include an antenna formed in a spiral coaxial with the protruding portion. The protruding portion and the antenna form a choke structure. A plasma processing apparatus.

Explanation of Signs

[0058] 1 Plasma processing apparatus 10 Plasma processing chamber 11 Substrate support portion 45 DC power supply 50, 90 Filter circuit 51, 51a Housing 52 Input port 53, 56, 56a Outer conductor 54, 57, 57a Inner conductor 55, 55a Output port 58 End 59 Central protruding portion 61, 61a Power supply line 62 Base 65 Antenna 65b, 65c Surface 66 Dielectric 67 Fin

Claims

1. A filter circuit comprising a housing formed of a conductor and having an input port and an output port formed of an outer conductor and an inner conductor, the housing being configured to have a ground potential together with the outer conductors of the input port and the output port; a protrusion formed of a conductor, connected to the housing, and configured to protrude spirally inside the housing; a power supply line provided inside the housing and insulated from the housing; wherein the power supply line is an input-side conductor which is the inner conductor of the input port, is an output-side conductor which is the inner conductor of the output port, is connected to the input-side conductor and the output-side conductor, and is configured to include an antenna formed spirally and coaxial with the protrusion; the protrusion and the antenna form a choke structure; a filter circuit.

2. Furthermore, a dielectric is configured to be provided between the housing and the power supply line, The filter circuit according to claim 1.

3. The input port and the output port have a coaxial structure, The filter circuit according to claim 1 or 2.

4. The choke structure is composed of a plurality of fins, the plurality of fins are alternately arranged with a first fin connected to the base of the protrusion and a second fin connected to the base of the antenna; The filter circuit according to claim 1 or 2.

5. The plurality of fins are two fins, namely the first fin and the second fin, which are formed spirally, The filter circuit according to claim 4.

6. The space between the housing, the protrusion and the antenna from the outer peripheral side surface to the central surface of the base of the antenna forms the choke structure based on a length of 1 / 4 wavelength of an electromagnetic wave to be blocked; The filter circuit according to claim 1 or 2.

7. The protrusion and the antenna adjust the number of turns of the spiral based on the wavelength of the electromagnetic wave to be blocked; The filter circuit according to claim 1 or 2.

8. The protrusion and the antenna adjust the number of turns of one of them so that the number of turns of each is different; The filter circuit according to claim 7.

9. The filter circuit according to claim 1 or 2 further includes a drive mechanism capable of adjusting the distance between the base of the protrusion and the base of the antenna; The filter circuit according to claim 1 or 2.

10. A plasma processing apparatus, wherein the plasma processing apparatus comprises a processing chamber, An electrode provided in the processing container to which two or more frequencies are applied, and a filter circuit, wherein the filter circuit is formed of a conductor, includes an input port and an output port formed of an outer conductor and an inner conductor, and a housing configured to have a ground potential together with the outer conductors of the input port and the output port, is formed of a conductor, is connected to the housing, and has a protruding portion configured to protrude spirally into the housing, is provided in the housing and is insulated from the housing, and has a power supply line, wherein the power supply line is an input side conductor that is the inner conductor of the input port, is an output side conductor that is the inner conductor of the output port, is connected to the input side conductor and the output side conductor, and is configured to include an antenna formed in a spiral coaxial with the protruding portion, the protruding portion and the antenna form a choke structure, a plasma processing apparatus.

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