Filter circuit and plasma processing apparatus

Abstract

To achieve a simple and compact high frequency filter.SOLUTION: A filter circuit has a housing, a partition part, and a power supply line. The housing is formed of an electric conductor, comprises an input-output port formed of an outside electric conductor and an inside electric conductor, is at ground potential together with the outside electric conductor of the input-output port, and has an internal space extending in a first direction and a second direction orthogonal to the first direction in plan view. The partition part is formed of an electric conductor, is connected to the housing, and partitions the internal space. The power supply line is provided inside the housing and electrically insulated from the housing. The power supply line comprises an input side electric conductor that is an inside electric conductor of an input port, an output side electric conductor that is an inside electric conductor of an output port, an antenna part that is connected to the input side electric conductor and the output side electric conductor and extends in the internal space to be laminated on the partition part, and an antenna base that connects the input side electric conductor, output side electric conductor, and antenna part to each other. In the internal space, the dimension in the first direction from the antenna base is larger than the dimension in the second direction from the antenna base.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] The plasma processing apparatus disclosed in Patent Document 1 includes a processing vessel in which plasma processing is performed, a mounting table arranged on a plate-shaped conductive base with a space therebetween within the processing vessel and on which a substrate to be processed is placed and held, a high-frequency electrode provided on the mounting table, a high-frequency power supply unit for applying a constant high-frequency voltage 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 arranged outside the processing vessel, a coil for attenuating or blocking high-frequency noise entering the heater power supply line via the heating element, and a filter unit having a casing for accommodating this coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-99585 Summary of the Invention [Problem 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 problem]

[0005] A filter circuit according to one embodiment of the present disclosure includes a housing, a partition, and a feed line. The housing is formed of a conductor and includes an input port and an output port formed by an outer conductor and an inner conductor. The housing, together with the outer conductors of the input and output ports, is at ground potential. The internal space is configured to extend in a first direction and a second direction perpendicular to the first direction in a plan view. The partition is formed of a conductor and connected to the housing, and is configured to divide the internal space. The feed line is provided within the housing and insulated from the housing. The feed line is configured to include an input conductor that is the inner conductor of the input port, an output conductor that is the inner conductor of the output port, an antenna unit connected to the input and output conductors and extending into the internal space so as to be stacked on the partition, and an antenna base that connects the input conductor, the output conductor, and the antenna unit. The internal space has a dimension from the antenna base in the first direction that is greater than a dimension from the antenna base in the second direction. [Effects of the Invention]

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

[0007] [Figure 1] 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. [Figure 2] FIG. 2 is a perspective view showing an example of a filter circuit according to this embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing an example of the AA cross section of FIG. [Figure 4] FIG. 4 is a cross-sectional view showing an example of the cross section BB of FIG. [Figure 5] FIG. 5 is a cross-sectional view showing an example of the CC cross section of FIG. [Figure 6] FIG. 6 is a diagram showing an example of a simulation result of an electric field distribution in a cross-sectional view of the filter circuit according to this embodiment. [Figure 7]FIG. 7 is a diagram showing an example of a simulation result of the electric field distribution in the XY plane of the filter circuit according to this embodiment. [Figure 8] FIG. 8 is a graph showing an example of the frequency characteristics of the filter circuit according to this embodiment. [Figure 9] FIG. 9 is a graph showing an example of the relationship between the length of the housing in the X direction and the filter frequency. [Figure 10] FIG. 10 is a graph showing an example of the relationship between the length of the housing in the Y direction and the filter frequency. [Figure 11] FIG. 11 is a graph showing an example of the relationship between the filter frequency and the characteristic parameters according to this embodiment. [Figure 12] FIG. 12 is a diagram showing an example of changes in filter characteristics depending on the contact pattern between the side surface of the housing and the partition. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] In a plasma processing apparatus, a power supply located outside the processing chamber is connected to an electrostatic chuck and a heater provided on a substrate support section that supports a substrate to be processed. Because the substrate support section constitutes a lower electrode for generating plasma, the high frequency waves used to generate plasma can affect the power supply lines to the electrostatic chuck and the heater. For this reason, high frequency filters composed of a coil and a capacitor are inserted in these power supply lines. However, high frequency filters composed of a coil and a capacitor have a complex structure and large dimensions. Therefore, it is expected that a simple and compact high frequency filter can be realized by shortening the widthwise dimension when installed along the length of the power supply line.

[0010] [Configuration of plasma processing system] An exemplary configuration of a plasma processing system will be described below. FIG. 1 is a schematic cross-sectional view illustrating an exemplary 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 controller 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, an exhaust system 40, a DC power supply 45, and a filter circuit 50. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion 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, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas into the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a 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 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0012] 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 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 the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. 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 is applied to the electrostatic electrode 1111b from the DC power supply 45, an electrostatic attractive force is generated between the electrostatic chuck 1111 and the substrate W. The generated electrostatic attractive force attracts the substrate W to the electrostatic chuck 1111, and the substrate W is held by the electrostatic chuck 1111.

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

[0014] The substrate support 11 may also include a temperature adjustment 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 adjustment 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 a gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0015] The showerhead 13 is configured to introduce at least one processing 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 multiple gas inlets 13c. The processing 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 multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 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 a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the 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. This generates a plasma 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 generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. In addition, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0018] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating 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 generating unit 31a may be configured to generate multiple 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 generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and 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 generating unit 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal (bias DC signal) is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the 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 rectangular, trapezoidal, triangular, or combination thereof. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either 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 period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0022] The exhaust system 40 may be connected to, for example, a gas exhaust port 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 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.

[0023] When plasma is generated in the plasma processing space 10s, the filter circuit 50 removes the influence of high-frequency power for plasma generation or bias applied to the DC power supply 45. The filter circuit 50 passes DC applied from the DC power supply 45 to the electrostatic electrode 1111b and blocks high-frequency power flowing in the reverse direction from the electrostatic electrode 1111b. In other words, the filter circuit 50 is provided in a power supply line (first power supply line) that supplies power to an electrode exposed to electromagnetic waves for generating plasma in the plasma processing chamber 10.

[0024] The controller 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described in this disclosure. The controller 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the controller 2 may be included in the plasma processing apparatus 1. The controller 2 may include a processor 2a1, a storage unit 2a2, and a communication interface 2a3. The controller 2 may be implemented, for example, by a computer 2a. The processor 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processor 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processor 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0025] [Structure of filter circuit 50] Next, the filter circuit 50 will be described in detail with reference to FIGS. 2 to 5. FIG. 2 is a perspective view showing an example of a filter circuit according to this embodiment. FIG. 3 is a cross-sectional view showing an example of the AA cross section of FIG. 2. In the following description, the longitudinal direction of the filter circuit 50 will be described as the X direction along the X axis, and the lateral direction will be described as the Y direction along the Y axis. The direction along the Z axis perpendicular to the X axis and the Y axis will be described as the Z direction. The X direction is an example of a first direction, the Y direction is an example of a second direction, and the Z direction is an example of a third direction. The cross sections shown in FIGS. 3 to 5 illustrate a case where air is used as a dielectric 68, which will be described later. As shown in FIGS. 2 and 3, the filter circuit 50 has a housing 51. The housing 51 is made of a conductor such as aluminum or copper. The housing 51 also includes an input port 52 and an output port 55. In this embodiment, since the high frequency power is cut off, the description will be given with the flow direction of the high frequency power as the reference, with the side connected to the electrostatic electrode 1111b as the input port 52 and the side connected to the DC power supply 45 as the output port 55. Note that the connections of the input port 52 and the output port 55 may be interchanged.

[0026] The input port 52 and the output port 55 are formed by outer conductors 53 and 56 and inner conductors 54 and 57, respectively. 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 and 56 and is at ground potential together with the grounded plasma processing chamber 10 via the coaxial cable connected to the input port 52 and the frame on which the filter circuit 50 is installed. That is, the housing 51 is formed of a conductor, has the input port 52 and the output port 55 formed by the outer conductors 53 and 56 and the inner conductors 54 and 57, and is at ground potential together with the outer conductors 53 and 56 of the input port 52 and the output port 55. The housing 51 has, for example, a rectangular parallelepiped shape and has a bottom surface 58 and a top surface 59 that intersect with the Z direction of the rectangular parallelepiped, side surfaces 60a and 60b that intersect with the X direction, and side surfaces 60c and 60d that intersect with the Y direction. That is, the housing 51 is configured such that the internal space thereof expands in the X and Y directions in a plan view (as viewed from the Z direction). The corners of the internal space in the X and Y directions may be rounded. The housing 51 has an input port 52 formed on a side surface 60a, and an output port 55 formed on a side surface 60b opposite the side surface 60a. The inner conductors 54 and 57 of the input port 52 and the output port 55 are connected to side surfaces 63 and 64, respectively, of an upper portion 62a of an antenna base 62 located approximately at the center of the X- and Y-direction plane in the internal space of the housing 51. That is, the input port 52 and the output port 55 extend in the X direction passing through the antenna base 62. The inner conductor (input side conductor) 54 of the input port 52, the inner conductor (output side conductor) 57 of the output port 55, the antenna unit 65, and the antenna base 62 form a feeder line 61 insulated from the housing 51. The power supply line 61 is an example of a second power supply line, and constitutes a part of a first power supply line which is a path for supplying direct current from the DC power supply 45 to the electrostatic electrode 1111b.

[0027] The antenna base 62 connects the inner conductors 54, 57, which are the input and output conductors, to the antenna unit 65. The antenna base 62 has, for example, a cylindrical shape and extends in the Z direction. The antenna unit 65 is provided on the Z-direction lower surface 58 of the inner conductors 54, 57 and has a first fin 66 and a second fin 67. The second fin 67 includes, for example, multiple second fins 67a to 67c. The first fin 66 and the second fin 67 are formed of a plate-shaped conductor such as aluminum or copper and are connected to the antenna base 62 approximately at the center of the plane in the X and Y directions. The first fin 66 is, for example, thicker than each of the second fins 67a to 67c. Note that the first fin 66 may have the same thickness as each of the second fins 67a to 67c. That is, the antenna unit 65 is provided so as to extend from the antenna base 62 in the X and Y directions. Furthermore, the antenna unit 65 does not contact the four side surfaces 60a to 60d of the housing 51. That is, the antenna unit 65 has a rectangular shape that is slightly smaller than the top surface 59 in a plan view (when viewed from the Z direction).

[0028] The interior space of the housing 51 is provided with a partition 70, which is made of a conductor such as aluminum or copper and is connected to the housing 51 while dividing the interior space of the housing 51. The partition 70 includes, for example, multiple partitions 70a-70c. The partition 70 is made of a plate-shaped conductor such as aluminum or copper and is connected to the side surfaces 60a-60d. The partition 70 is disposed annularly with respect to the cylindrical antenna base 62 at a fixed interval (interval 71 in FIG. 4, described later). The partition 70 contacts the four side surfaces 60a-60d of the housing 51; however, it is sufficient that the partition 70 contacts at least two side surfaces 60c and 60d that intersect with the Y direction and one side surface 60a or one side surface 60b that intersects with the X direction among the side surfaces 60a-60d of the housing 51. In other words, the partition 70 does not necessarily need to contact the side surfaces 60a or 60b.

[0029] The antenna unit 65 and the partition unit 70 are formed so that the first fin 66, the second fins 67a-67c, and the partition units 70a-70c are alternately intertwined in the AA cross section. That is, the antenna unit 65 is connected to the inner conductors 54, 57, which are the input-side conductor and the output-side conductor, and extends into the internal space so as to be stacked with the partition unit 70. That is, the filter circuit 50 is formed so that the transmission path length in the space between the first fin 66 and the second fins 67a-67c and the partition units 70a-70c and the lower surface 58 forms a choke structure based on the length of a quarter wavelength of the frequency to be blocked. That is, in the filter circuit 50, the space between the housing 51 and the partition 70 and the antenna unit 65, from the end in the X direction of the first fin 66 of the antenna unit 65 that is closest to the input port 52 and the output port 55 to the center of the end 62b of the antenna base 62 to which the second fin 67c that is farthest from the input port 52 and the output port 55 is connected, forms a choke structure based on the length of a quarter wavelength of the electromagnetic wave to be blocked. In the following description, the frequency to be blocked in the filter circuit 50 will also be simply referred to as the filter frequency.

[0030] FIG. 4 is a cross-sectional view showing an example of the BB cross section of FIG. 3. FIG. 5 is a cross-sectional view showing an example of the CC cross section of FIG. 3. As shown in FIG. 4, the partitions 70a to 70c connected to the housing 51 are disposed at a fixed interval 71 from the antenna base 62. On the other hand, as shown in FIG. 5, the second fins 67a to 67c connected to the antenna base 62 are disposed at a fixed interval 72 from the side surfaces 60a to 60d of the housing 51. As shown in FIGS. 2 and 3, the first fin 66, like the second fins 67a to 67c, is also disposed at a fixed interval from the side surfaces 60a to 60d of the housing 51. Here, it is preferable that the second fins 67a to 67c have dimensions such that the total propagation length (path length) in the X direction is λ / 4+α, where λ is the wavelength of the electromagnetic wave. Here, α is a parameter for fine adjustment. In contrast, the second fins 67a to 67c can be sized so that the total propagation length (path length) in the Y direction is sufficiently smaller than λ / 4, where λ is the wavelength of the electromagnetic wave. For example, if the filter frequency is 220 MHz, the dimension X can be 55 mm and the dimension Y can be 25 mm in FIG. 5. That is, the external dimensions of the housing 51 are 110 mm in the X direction and 50 mm in the Y direction.

[0031] 3, the filter circuit 50 has a dielectric 68 between the housing 51 and the feed line 61. That is, the dielectric 68 is filled between the inner conductors 54, 57 and the upper surface 59 and the side surfaces 60a-60d, between the inner conductors 54, 57 and the first fin 66, and between the first fin 66 and the partition 70a. The dielectric 68 is also filled between the second fins 67a-67c and the partitions 70a-70c, between the second fin 67c and the lower surface 58, and between the first fin 66 and the second fins 67a-67c and the side surfaces 60a-60d. If a solid material is used as the dielectric 68, the spaces between the first fin 66 and the second fins 67a-67c and the partitions 70a-70c can be easily filled with the dielectric 68 by sandwiching a sheet-like dielectric 68 between them. Similarly, a dielectric 68 is filled between the outer conductor 53 and the inner conductor 54 of the input port 52, and between the outer conductor 56 and the inner conductor 57 of the output port 55. The dielectric 68 may be, for example, air or PTFE (Poly Tetra Fluoro Ethylene). In other words, a dielectric 68 having a higher dielectric constant than air may be provided between the partition portion 70 and the antenna portion 65.

[0032] The total propagation length (path length) in the X direction of the filter circuit 50 is the space from the tip of the first fin 66, passing through the first fin 66, the second fin 67, and the partition 70, to the end 62b of the antenna base 62. In other words, this space forms a choke structure based on the length of a quarter wavelength of the electromagnetic wave to be blocked. The total propagation length (path length) in the X direction of the filter circuit 50 is the transmission path length W1 shown in FIG. 6, which will be described later. For example, when the above-mentioned fine-tuning parameter α is defined as the following equation (1), the transmission path length W1 can be expressed by the following equation (2):

[0033] α=4×λ g / 100 (1) W1=λ g / 4±α (2)

[0034] For example, if the dimension of the second fin 67 is dimension X=55 mm as shown in Figure 5, the transmission path length W1 is 192.5 mm one way, with 3.5 round trips of 55 mm, and is 385 mm round trips. For example, if the frequency of the high frequency power, which is the electromagnetic wave to be blocked, is 220 MHz and air with a relative dielectric constant of 1 is used as the dielectric 68, then λ=1.36 m, and so λ g =λ / (√1)=1360mm, λ g / 4=340 mm, and α=54.4 mm. In this case, the transmission path length W1 is W1=340±54.4 mm according to formula (2). On the other hand, when dimension X=55 mm, the transmission path length W1 is 385 mm, which satisfies the range of formula (2). Note that when PTFE with a relative dielectric constant of 2.1 is used for dielectric 68, the dimensions of first fin 66, second fin 67, and the dimensions of stacked partition section 70 can each be reduced.

[0035] [Simulation Results] Next, the results of a simulation of the electric field distribution of the filter circuit 50 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a diagram showing an example of the results of a simulation of the electric field distribution in a cross-sectional view of the filter circuit according to this embodiment. First, the transmission path length W1 will be described in the cross-section of the filter circuit 50 in Fig. 6. The transmission path length W1 is the path of the complex dielectric 68 in a section 83 from a position 81 of the tip of the first fin 66 to a position 82 of the end 62b of the antenna base 62. In other words, the transmission path length W1 is the path from the position 81 of the tip of the first fin 66 to the position 82 of the end 62b, passing through the spaces between the first fin 66 and the partition 70a, between the partition 70a and the second fin 67a, between the second fin 67a and the partition 70b, between the partition 70b and the second fin 67b, between the second fin 67b and the partition 70c, between the partition 70c and the second fin 67c, between the second fin 67c and the bottom surface 58, and the space that contacts the side surface or the side surface 60a of the antenna base 62 and connects these spaces in the Z direction. Note that while FIG. 6 illustrates the input port 52 side, the output port 55 side also has the same transmission path length W1. 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. In other words, a portion of the electromagnetic wave to be blocked travels back and forth along the transmission path length W1, and therefore cancels out with the electromagnetic wave (traveling wave) traveling directly from the input port 52 side to the output port 55 side, and is not output to the output port 55 side.

[0036] Simulation result 80 shown in FIG. 6 shows the electric field distribution when 220 MHz, 1000 W of high-frequency power is input from input port 52. In simulation result 80, the electric field intensity is relatively high in the space where dielectric 68 exists from input port 52 to side surface 63 of antenna base 62. Furthermore, in the portion of transmission path length W1, which is a complicated path from position 81 to position 82, the electric field intensity is relatively high in the space between first fin 66 and second fin 67 and partition 70. Note that the electric field distribution in the right half of FIG. 6 is hidden by the arrow of transmission path length W1. Furthermore, the electric field intensity is relatively low in the space between first fin 66 and second fin 67 and side surface 60 a, and in the space between partition 70 and antenna base 62, compared to the space between first fin 66 and second fin 67 and partition 70. Furthermore, the electric field intensity is almost zero from side surface 64 of antenna base 62 to output port 55. In other words, the antenna section 65 and the partition section 70 inside the housing 51 generate a reflected wave that is 180 degrees out of phase with the traveling wave, and the traveling wave and the reflected wave cancel each other out, resulting in an output of 0 W of 220 MHz high-frequency power from the output port 55.

[0037] FIG. 7 is a diagram illustrating an example of a simulation result of the electric field distribution in the XY plane of the filter circuit according to this embodiment. Similar to simulation result 80, simulation result 85 shown in FIG. 7 illustrates the electric field distribution when 220 MHz, 1000 W of high-frequency power is input from input port 52. Note that the cross section shown in FIG. 7 uses air as dielectric 68. Simulation result 85 shows that the electric field strength increases relatively along the inner conductor 54 from the input port 52 to the antenna base 62. In other words, the electric field strength decreases relatively near the side surfaces 60c and 60d in the XY plane. For example, it can be seen that even if the corners in the XY plane (the connection between side surfaces 60a and 60c) are rounded, this does not affect the electric field distribution. Note that electromagnetic waves can be considered TE waves in the space from input port 52 through antenna base 62 to output port 55.

[0038] 8 is a graph showing an example of the frequency characteristics of the filter circuit according to this embodiment. A graph 90 shown in FIG. 8 shows the frequency characteristics of the filter circuit 50 as a function of S-parameter S 21 In Figure 8, the vertical axis of the graph is S 21 The graph 90 represents the insertion loss, and the amount of attenuation increases toward the negative side. Also, in FIG. 8, the fundamental frequency (220 MHz) of the electromagnetic wave to be blocked (660 MHz) is shown as fundamental frequency 91, and the third harmonic (660 MHz) is shown as third harmonic 92. As shown in graph 90, the attenuation of filter circuit 50 is maximum at the fundamental frequency of 220 MHz, and the insertion loss is −62 dB. Furthermore, the insertion loss in the range of 180 MHz to 260 MHz is −30 dB or less. Furthermore, the insertion loss of filter circuit 50 is −58 dB at the third harmonic of 660 MHz. Furthermore, the insertion loss in the range of 640 MHz to 700 MHz is −30 dB or less. In other words, filter circuit 50 forms a bandstop filter with center frequencies of 220 MHz and 660 MHz. As described above, in this embodiment, a three-dimensional circuit in which the antenna unit 65 and the partition unit 70 are stacked in an internal space whose dimension in the X direction from the antenna base 62 is greater than the dimension in the Y direction from the antenna base 62 resonates the high-frequency wave of the frequency to be blocked. This allows for a simple and compact high-frequency filter for high-output high-frequency power, such as 1000 W in the VHF (Very High Frequency) band, to be realized. Furthermore, 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 causing a ground fault. Furthermore, in this embodiment, within a frequency range in which the insertion loss is −30 dB or less, it is possible to block electromagnetic waves (single-peak waveforms) whose frequency is variable using FM modulation or the like, and electromagnetic waves (broadband waveforms) with multiple frequencies generated as multitones. Furthermore, the filter circuit 50 can simultaneously attenuate and block both the fundamental frequency (220 MHz) and the third harmonic (660 MHz) of the electromagnetic wave to be blocked.

[0039] [Relationship between the length of the housing in the X and Y directions and the filter frequency] Next, the relationship between the length of the housing in the X and Y directions and the filter frequency will be described using FIGS. 9 to 11. The length in the X direction and the length in the Y direction in FIGS. 9 to 11 correspond to the dimensions X and Y shown in FIG. 5, respectively. The dimension X is the length from the center of the antenna base 62 to the end of the second fin 67 on the side of the side surface 60a, and the dimension Y is the length from the center line in the X direction passing through the input port 52 and the antenna base 62 to the end of the second fin 67 on the side of the side surface 60c. The lengths in the X direction and the Y direction may be based on the center of the gap 72 (the center of the transmission path) shown in FIG. 5 on the end side of the second fin 67. The lengths in the X direction and the Y direction may be half the dimensions of the housing 51 in the X direction and the Y direction (the lengths from the center of the antenna base 62 to the side surfaces 60a and 60c, respectively).

[0040] Fig. 9 is a graph showing an example of the relationship between the length of the housing in the X direction and the filter frequency. Graph 93 shown in Fig. 9 shows the relationship with the filter frequency when the length in the X direction (dimension X) is changed with the length in the Y direction (dimension Y) set to 20 mm. As shown in graph 93, there is a tendency for the filter frequency to decrease as the length in the X direction increases, from a filter frequency of 281 MHz when dimension X = 48 mm to a filter frequency of 219 MHz when dimension X = 108 mm.

[0041] Fig. 10 is a graph showing an example of the relationship between the length of the housing in the Y direction and the filter frequency. Graph 94 shown in Fig. 10 shows the relationship with the filter frequency when the length in the X direction (dimension X) is set to 48 mm and the length in the Y direction (dimension Y) is changed. As shown in graph 94, there is a tendency for the filter frequency to decrease as the length in the Y direction increases, from a filter frequency of 363 MHz when dimension Y = 15 mm to a filter frequency of 143 MHz when dimension X = 50 mm.

[0042] Here, consider generalizing graphs 93 and 94. The wave vector of the electromagnetic wave propagating in the filter circuit 50 is given by the following equation (3). Furthermore, from equation (3), the wave number k is given by the following equation (4). Therefore, the effective wavelength λ eff can be expressed by the following equation (5): Furthermore, based on equation (5), the characteristic parameter β is defined by the following equation (6).

[0043]

number

number

number

number

[0044] where λ x is the effective wavelength in the X direction, and λ y is the effective wavelength in the Y direction. Furthermore, X and Y are dimensions corresponding to the above-mentioned dimensions X and Y. That is, the dimension X is the length from the center of the antenna base 62 to the end of the second fin 67 on the side of the side surface 60a, and the dimension Y is the length from the center line in the X direction passing through the input port 52 and the antenna base 62 to the end of the second fin 67 on the side of the side surface 60c.

[0045] FIG. 11 is a graph showing an example of the relationship between the filter frequency and the characteristic parameter according to this embodiment. As shown in graph 95 of FIG. 11, it can be seen that there is a linear relationship between the filter frequency and the characteristic parameter β. That is, in this embodiment, the X and Y dimensions of the second fin 67 can be determined based on graph 95 in accordance with a desired filter frequency. That is, the internal space of the housing 51 can be configured such that the dimension in the X direction from the antenna base 62 is greater than the dimension in the Y direction from the antenna base 62. In other words, the filter frequency in the internal space is defined by the above equation (6). That is, in this embodiment, the X and Y dimensions (external dimensions) of the housing 51 in accordance with a desired filter frequency can be determined based on graph 95. In other words, when the filter circuit 50 is installed along the length direction (X direction) of the feed line 61, the width direction (Y direction) of the filter circuit 50 can be reduced. That is, the filter circuit 50 can make the length of one of the opposing sides of the housing 51 (the length in the Y direction of the side surfaces 60a, 60b) shorter than ¼ wavelength of the filter frequency. It should be noted that the difference between the dimensions of the second fin 67 and the dimensions of the housing 51 is within a range that can be absorbed by the fine-tuning parameter α in the above-described formula (1). In this manner, in this embodiment, the filter frequency can be calculated in a general-purpose manner by using the characteristic parameter β.

[0046] [Contact between the side of the housing and the partition] Next, changes in filter characteristics depending on the contact pattern between the side surfaces 60a to 60d of the housing 51 and the partition 70 will be described using FIG. 12. FIG. 12 is a diagram showing an example of changes in filter characteristics depending on the contact pattern between the side surfaces of the housing and the partition. Table 96 shown in FIG. 12 indicates cases where the characteristics of the filter circuit 50 are acceptable with a circle and cases where the characteristics are unacceptable with a cross. Furthermore, in Table 96, the vertical axis indicates the side surfaces 60a and 60b with which the partition 70 comes into contact, and the horizontal axis indicates the side surfaces 60c and 60d with which the partition 70 comes into contact. As shown in Table 96, if the partition 70 does not come into contact with either side surface 60c or 60d, the filter frequency (resonant frequency) shifts and the third harmonic cannot be blocked, resulting in unacceptable characteristics. On the other hand, when the partition 70 is in contact with both the side surfaces 60a and 60b, or when the partition 70 is in contact with one of the side surfaces 60a and 60b and the distance δ between the other and the side surface 60a or 60b is 2 mm or less, the characteristics are in an acceptable state. In other words, the characteristics are acceptable when the partition 70 is in contact with at least three side surfaces excluding one of the side surfaces 60a and 60b, and the distance δ between the non-contacting side surface 60a or 60b is 2 mm or less. Note that it is preferable that the partition 70 is in contact with the side surfaces 60a to 60d (contact on four surfaces). Furthermore, when the partition 70 is in contact with the side surfaces 60a to 60d, for example, λ g For example, gaps (for example, mesh, punched holes, etc.) of about 1 / 500 may be provided at the corners where the electric field strength is low.

[0047] As described above, according to this embodiment, the filter circuit 50 includes a housing 51, a partition 70, and a feed line 61. The housing 51 is formed of a conductor and includes an input port 52 and an output port 55 formed by outer conductors 53, 56 and inner conductors 54, 57. The housing 51, together with the outer conductors 53, 56 of the input port 52 and the output port 55, is at ground potential, and is configured so that the internal space extends in a first direction (X direction) and a second direction (Y direction) perpendicular to the first direction in a plan view. The partition 70 is formed of a conductor, is connected to the housing 51, and is configured to divide the internal space. The feed line 61 is provided within the housing 51 and is insulated from the housing 51. The feed line 61 is configured to include an input conductor which is the inner conductor 54 of the input port 52, an output conductor which is the inner conductor 57 of the output port 55, an antenna section 65 connected to the input conductor and the output conductor and extending into the internal space so as to be stacked with the partition section 70, and an antenna base 62 connecting the input conductor, the output conductor, and the antenna section 65. The dimension of the internal space in a first direction from the antenna base 62 is greater than the dimension in a second direction from the antenna base 62. As a result, a simple and compact high-frequency filter can be realized.

[0048] Furthermore, according to this embodiment, the filter frequency in the internal space is defined by the above-mentioned formula (6). In formula (6), β represents a characteristic parameter, X represents a dimension in a first direction, and Y represents a dimension in a second direction. As a result, the dimensions in the X and Y directions (external dimensions) of the housing 51 can be determined according to the desired filter frequency.

[0049] Furthermore, according to this embodiment, the partition 70 is installed so as to leave a constant gap 71 between it and the antenna base 62. As a result, a transmission path can be formed between the partition 70 and the antenna unit 65.

[0050] According to this embodiment, the antenna base 62 has a cylindrical shape. As a result, it is easy to maintain a constant distance 71 from the antenna base 62. By maintaining the distance 71 constant, it is possible to suppress phase shifts (polarizations) in the X and Y directions, and stabilize the characteristics of the filter circuit 50.

[0051] Furthermore, according to this embodiment, the input port 52 and the output port 55 extend in a first direction passing through the antenna base 62. The antenna base 62 extends in a third direction (Z direction) perpendicular to the first and second directions. The antenna unit 65 is provided so as to extend from the antenna base 62 in the first and second directions. As a result, a simple and compact high-frequency filter can be realized.

[0052] Furthermore, according to the present embodiment, the partition 70 is in contact with two side surfaces (side surfaces 60c and 60d) that intersect with the second direction among the side surfaces 60a to 60d of the housing 51. As a result, the frequency characteristics of the filter circuit 50 can be improved.

[0053] Furthermore, according to this embodiment, the shape of the internal space is a rectangular parallelepiped, which makes it possible to easily form the antenna portion 65 and the partition portion 70.

[0054] Furthermore, according to this embodiment, the partition 70 is in contact with the four side surfaces 60a to 60d of the housing 51. As a result, the frequency characteristics of the filter circuit 50 can be further improved.

[0055] Furthermore, according to this embodiment, the filter circuit 50 is configured to further include a dielectric 68 having a higher dielectric constant than air between the partition 70 and the antenna unit 65. As a result, a more compact high-frequency filter can be realized.

[0056] Furthermore, according to this embodiment, the space between the housing 51 and the partition 70 and the antenna unit 65, from the end in the first direction of the fin (first fin 66) of the antenna unit 65 that is closest to the input port 52 and the output port 55 to the center of the end 62b of the antenna base 62 to which the fin (second fin 67c) that is farthest from the input port 52 and the output port 55 is connected, 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 and the third harmonic.

[0057] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, and modifications may be made to the above-described embodiments without departing from the spirit and scope of the appended claims.

[0058] In the above embodiment, the transmission path length W1 is set to ¼ wavelength of the electromagnetic wave to be blocked, but is not limited to this. For example, the dimensions and number of layers of the antenna unit 65 and the partition unit 70 may be set so that the transmission path length is such that the forward wave and the reflected wave cancel each other out.

[0059] In the above embodiment, the filter circuit 50 is connected to the electrostatic electrode 1111b inside the electrostatic chuck 1111. However, the present invention is not limited to this. For example, the filter circuit 50 may be connected to a heater (not shown) provided inside the substrate support 11.

[0060] In the above embodiment, the plasma processing apparatus 1 is described as an example in which a process such as etching is performed on a substrate W using capacitively coupled plasma as a plasma source, but the disclosed technology is not limited to this. As long as the apparatus performs a process on a substrate W using plasma, the plasma source is not limited to capacitively coupled plasma, and any plasma source such as inductively coupled plasma, microwave plasma, or magnetron plasma can be used.

[0061] The present disclosure can also be configured as follows. (1) a housing formed of a conductor, including an input port and an output port formed by an outer conductor and an inner conductor, the housing being at ground potential together with the outer conductor of the input port and the output port, and configured so that an internal space thereof extends in a first direction and a second direction perpendicular to the first direction in a plan view; a partition portion formed of a conductor, connected to the housing, and configured to partition the internal space; a power supply line provided within 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; an output-side conductor that is the inner conductor of the output port; an antenna portion connected to the input conductor and the output conductor and extending into the internal space so as to be stacked on the partition portion; an antenna base portion connecting the input conductor, the output conductor, and the antenna portion, The internal space has a dimension in the first direction from the antenna base that is larger than a dimension in the second direction from the antenna base. Filter circuit. (2) The filter frequency in the internal space is defined by the following formula (A1): 2. The filter circuit of claim 1.

number

[0062] 1. Plasma processing equipment 10 Plasma Processing Chamber 11 Substrate support 45 DC power supply 50 Filter circuit 51 Case 52 input ports 53,56 Outer conductor 54,57 Inner conductor 55 output ports 60a~60d Side 61 Power Supply Line 62 Antenna base 62b end 65 Antenna section 66 First Fin 67, 67a~67c Second fin 68 Dielectric 70, 70a~70c Partition 71 interval

Claims

1. a housing formed of a conductor, including an input port and an output port formed by an outer conductor and an inner conductor, the housing being at ground potential together with the outer conductor of the input port and the output port, and configured so that an internal space thereof extends in a first direction and a second direction perpendicular to the first direction in a plan view; a partition portion formed of a conductor, connected to the housing, and configured to partition the internal space; a power supply line provided within 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; an output-side conductor that is the inner conductor of the output port; an antenna portion connected to the input conductor and the output conductor and extending into the internal space so as to be stacked on the partition portion; an antenna base portion connecting the input conductor, the output conductor, and the antenna portion, the internal space has a dimension in the first direction from the antenna base that is greater than a dimension in the second direction from the antenna base; Filter circuit.

2. The filter frequency in the internal space is defined by the following equation (1):

2. The filter circuit according to claim 1. [Equation 1] In the above formula (1), β represents a characteristic parameter, X represents the dimension in the first direction, and Y represents the dimension in the second direction.

3. The partition is installed at a fixed distance from the antenna base.

3. The filter circuit according to claim 1.

4. The antenna base is cylindrical.

3. The filter circuit according to claim 1.

5. the input port and the output port extend in the first direction through the antenna base; the antenna base extends in a third direction perpendicular to the first direction and the second direction; The antenna portion is provided so as to extend from the antenna base portion in the first direction and the second direction.

3. The filter circuit according to claim 1.

6. the partition portion is in contact with two of the side surfaces of the housing that intersect with the second direction; 6. The filter circuit according to claim 5.

7. The shape of the internal space is a rectangular parallelepiped.

3. The filter circuit according to claim 1.

8. The partition portion is in contact with four side surfaces of the housing.

8. The filter circuit according to claim 7.

9. Furthermore, a dielectric having a higher dielectric constant than air is provided between the partition and the antenna.

3. The filter circuit according to claim 1.

10. a space between the housing and the partition and the antenna unit, from an end in the first direction of a fin of the antenna unit that is closest to the input port and the output port to a center of an end of the antenna base to which a fin farthest from the input port and the output port is connected, forms a choke structure based on a length of a quarter wavelength of an electromagnetic wave to be blocked; 3. The filter circuit according to claim 1.

11. A plasma processing apparatus, The plasma processing apparatus includes: A processing vessel; a filter circuit provided in a first power supply line that supplies power to an electrode that is exposed to electromagnetic waves for generating plasma in the processing chamber, The filter circuit comprises: a housing formed of a conductor, including an input port and an output port formed by an outer conductor and an inner conductor, the housing being at ground potential together with the outer conductor of the input port and the output port, and configured so that an internal space thereof extends in a first direction and a second direction perpendicular to the first direction in a plan view; a partition portion formed of a conductor, connected to the housing, and configured to partition the internal space; a second power supply line provided within the housing and insulated from the housing; The second 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 portion connected to the input conductor and the output conductor and extending into the internal space so as to be stacked on the partition portion; an antenna base portion connecting the input conductor, the output conductor, and the antenna portion, the internal space has a dimension in the first direction from the antenna base that is greater than a dimension in the second direction from the antenna base; Plasma processing equipment.

Images