Plasma processing apparatus and antenna assembly

Abstract

The present invention relates to a plasma processing apparatus and an antenna assembly. The electric field intensity at the time of plasma processing is reduced, and the uniformity of the plasma distribution to the substrate is improved. The plasma processing apparatus has a main coil provided at an upper portion or above a plasma processing chamber, and a sub-coil assembly provided at a radially inner side or a radially outer side of the main coil. The sub-coil assembly includes a first spiral coil and a second spiral coil. Each turn portion of the first spiral coil and each turn portion of the second spiral coil are alternately arranged in a vertical direction. A first upper side terminal of the first spiral coil is connected to a ground potential via one or more capacitors, and a first lower side terminal of the first spiral coil is connected to the ground potential. A second upper side terminal of the second spiral coil is connected to the ground potential via one or more capacitors or one or more other capacitors, and a second lower side terminal of the second spiral coil is connected to the ground potential.

Description

Technical Field

[0001] This disclosure relates to plasma processing apparatus and antenna assemblies. Background Technology

[0002] Patent Document 1 discloses a plasma processing apparatus comprising: an antenna that generates plasma of a processing gas within a cavity by supplying high frequency to the cavity; and a power supply unit that supplies high-frequency power to the antenna. The antenna has an outer coil and an inner coil inductively coupled to the outer coil.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-67503 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The technology disclosed herein reduces the electric field intensity during plasma processing and improves the uniformity of plasma distribution with respect to the substrate.

[0008] Solution for solving the problem

[0009] This disclosure provides a plasma processing apparatus comprising: a plasma processing chamber; a main coil disposed above or above the plasma processing chamber; a secondary coil assembly disposed radially inside or radially outside the main coil, the secondary coil assembly including a first helical coil having one or more turns and a second helical coil having one or more turns, the turns of the first helical coil and the turns of the second helical coil being alternately arranged in the vertical direction; the first helical coil having a first upper terminal at its upper end and a first lower terminal at its lower end, the first upper terminal being connected to a ground potential via one or more capacitors, the first lower terminal being connected to a ground potential; the second helical coil having a second upper terminal at its upper end and a second lower terminal at its lower end, the second upper terminal being connected to a ground potential via the one or more capacitors or one or more other capacitors, the second lower terminal being connected to a ground potential; and an RF power supply unit configured to supply RF power to the main coil.

[0010] The effects of the invention

[0011] According to this disclosure, the electric field strength during plasma processing can be reduced, and the uniformity of plasma distribution with respect to the substrate can be improved. Attached Figure Description

[0012] Figure 1 It is a schematic cross-sectional view showing the structure of the plasma processing system.

[0013] Figure 2 It is a schematic cross-sectional view showing the structure of the antenna.

[0014] Figure 3 It is a schematic three-dimensional diagram that represents the general structure of the antenna.

[0015] Figure 4 It is a schematic three-dimensional diagram showing the structure of the secondary coil assembly.

[0016] Figure 5 This is a top view showing the general structure of the secondary coil assembly.

[0017] Figure 6 This is a bottom view showing the general structure of the sub-coil assembly.

[0018] Figure 7 This is a schematic side view showing the structure of the secondary coil assembly.

[0019] Figure 8 This is a schematic side view showing the structure of the secondary coil assembly.

[0020] Figure 9 This is a graph showing the experimental results of the comparative examples.

[0021] Figure 10 This is a graph representing the experimental results of this implementation method.

[0022] Figure 11 This is a schematic perspective view showing the structure of the sub-coil assembly in other embodiments.

[0023] Figure 12 This is a schematic perspective view showing the structure of the sub-coil assembly in other embodiments.

[0024] Figure 13 This is a schematic perspective view showing the structure of the sub-coil assembly in other embodiments.

[0025] Figure 14 This is a schematic perspective view showing the structure of the sub-coil assembly in other embodiments.

[0026] Figure 15 This is a schematic perspective view showing the structure of the antenna in the first example of another embodiment.

[0027] Figure 16 This is a schematic perspective view showing the structure of the antenna in the second example of another embodiment.

[0028] Figure 17This is a schematic perspective view showing the structure of the antenna in the third example of another embodiment.

[0029] Figure 18 This is a schematic perspective view showing the structure of the antenna in the fourth example of another embodiment.

[0030] Figure 19 This is a schematic perspective view showing the structure of the antenna in the fifth example of another embodiment.

[0031] Figure 20 This is a schematic perspective view showing the structure of the antenna in the sixth example of another embodiment.

[0032] Figure 21 This is a schematic perspective view showing the structure of an antenna in other embodiments.

[0033] Figure 22 This is a schematic perspective view showing the structure of an antenna in other embodiments. Detailed Implementation

[0034] In the manufacturing process of semiconductor devices, semiconductor wafers (hereinafter referred to as "wafers") undergo plasma treatments such as etching and film deposition. In plasma treatment, plasma is generated by exciting a processing gas, and this plasma is used to process the wafer.

[0035] As a type of plasma source, inductively coupled plasma (ICP) can be used, for example. The plasma processing apparatus disclosed in Patent Document 1 is such an inductively coupled plasma processing apparatus, which has an antenna with an outer coil and an inner coil.

[0036] The outer coil is formed into a roughly circular vortex with more than two loops, and is positioned above the dielectric window with the central axis of the outer coil's shape aligned with the Z-axis. The outer coil is configured such that both ends of the circuit constituting the outer coil are open, and power is supplied from the power supply unit to the midpoint or vicinity of the circuit. It is grounded near the midpoint and resonates at half the wavelength of the high-frequency power supplied from the power supply unit.

[0037] The inner coil is formed into a roughly circular ring, positioned above the dielectric window with its central axis aligned with the Z-axis. The two ends of the circuit constituting the inner coil are connected by a capacitor, and the inner coil is inductively coupled to the outer coil.

[0038] The inventors recognized that, when using the antenna disclosed in Patent Document 1, the endpoint electric field of the resonant mechanism is relatively high. This endpoint electric field affects the plasma density distribution (hereinafter referred to as "plasma distribution") on the lower surface of the dielectric window, i.e., within the cavity, resulting in uneven etching rates. Therefore, based on the viewpoint of generating uniform plasma using an induced magnetic field, it is desirable to reduce the electric field strength required for plasma ignition.

[0039] Furthermore, in antenna assemblies comprising a main coil and a sub-coil, as disclosed in Patent Document 1 above, higher etching rates and greater controllability are required, which can be addressed by increasing the output of RF power. Increasing the output of RF power contributes to increasing the plasma density within the cavity; additionally, it is necessary to increase the current flowing from the main coil to the sub-coil to homogenize the plasma density. In this case, due to the temperature rise of the sub-coil, a design with high heat resistance is required. Therefore, a design that suppresses heat generation and a design that ensures uniform plasma distribution when introduced towards the center are needed.

[0040] The technology disclosed herein reduces the electric field intensity during plasma processing and improves the uniformity of plasma distribution with respect to the substrate. Hereinafter, the plasma processing apparatus of this embodiment will be described with reference to the accompanying drawings. Furthermore, in this specification and the drawings, elements having substantially the same functional structure are labeled with the same reference numerals, thereby omitting repeated descriptions.

[0041] <Structure of the Plasma Processing Device>

[0042] First, the structure of a plasma processing system according to one embodiment will be described. Figure 1 This is a schematic cross-sectional view showing the structure of the plasma processing system. The plasma processing system includes a plasma processing device 1 and a control device 50. Furthermore, the plasma processing device 1 in this embodiment is a plasma processing device that uses inductively coupled plasma.

[0043] The plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply unit 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window 10a and a sidewall 10b, and houses a substrate (wafer) W. The dielectric window 10a forms the upper part of the plasma processing chamber 10 and has an opening in the upper part of the sidewall 10b. The dielectric window 10a and the sidewall 10b define a plasma processing space 10s within the plasma processing chamber 10.

[0044] Additionally, the plasma processing apparatus 1 includes a substrate (wafer) support 11, a gas inlet 13, and an antenna 14. The substrate support 11 is disposed within the plasma processing space 10s. The antenna 14 is disposed on the upper part or above the plasma processing chamber 10 (dielectric window 10a). Furthermore, the structure of the antenna 14 will be described later.

[0045] The substrate support portion 11 includes a main body portion 111 and an annular member (edge ​​ring) 112. The main body portion 111 has a central region (substrate support surface) 111a for supporting the substrate W and an annular region (edge ​​ring support surface) 111b for supporting the annular member 112. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111. The substrate W is disposed on the central region 111a of the main body portion 111, and the annular member 112 is disposed on the annular region 111b of the main body portion 111 in such a way that it surrounds the substrate W on the central region 111a of the main body portion 111. In one embodiment, the main body portion 111 includes an electrostatic chuck and a conductive member. The conductive member is disposed below the electrostatic chuck. The conductive member functions as an RF electrode by the supply of RF (Radio Frequency) power, and the upper surface of the electrostatic chuck functions as the substrate support surface 111a. Additionally, although not shown in the illustrations, in one embodiment, the substrate support 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck and the substrate W to a target temperature. The temperature control module may also include a heater, a flow path, or a combination thereof. A temperature-regulating fluid such as a refrigerant or heat transfer gas flows in the flow path.

[0046] The gas inlet 13 is configured to supply (introduce) at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. In one embodiment, the gas inlet 13 is disposed above the substrate support 11 and may also include a central gas injector (CGI) mounted on the central opening formed in the dielectric window 10a. Alternatively or based on this, the gas inlet 13 may also include one or more side gas injectors (SGIs) mounted on one or more openings formed in the sidewall 10b.

[0047] The gas supply unit 20 may also 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 one or more processing gases from their respective gas sources 21 to the gas inlet unit 13 via their respective flow controllers 22. Each flow controller 22 may, for example, include a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may also include one or more flow modulation devices for modulating or pulsedizing the flow rate of one or more processing gases.

[0048] The power supply unit 30 includes an RF power supply unit. The RF power supply unit is configured to supply at least one RF signal (RF power, such as a source RF signal and a bias RF signal) to the conductive member of the substrate support 11 and the antenna 14. As a result, plasma is formed by at least one processing gas supplied to the plasma processing space 10s.

[0049] In one embodiment, the RF power supply unit includes a first RF generation unit and a second RF generation unit. The first RF generation unit is connected to the main coil 200 of the antenna 14 (described later) 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 27 MHz to 100 MHz. The generated source RF signal is supplied to the main coil 200 of the antenna 14. The second RF generation unit is connected to the conductive member of the substrate support 11 and is configured to generate a bias RF signal (bias RF power). The generated bias RF signal is supplied to the conductive member of the substrate support 11. In one embodiment, the bias RF signal has a frequency lower than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 13.56 MHz. Furthermore, in various embodiments, the amplitude of at least one of the source RF signal and the bias RF signal may be pulsed or modulated. Amplitude modulation also includes pulsed the RF signal amplitude between an on state and an off state, or between two or more different on states.

[0050] Alternatively, the power supply unit 30 may also include a DC power supply unit. The DC power supply unit includes a bias DC generation unit. In one embodiment, the bias DC generation unit is connected to a conductive member of the substrate support unit 11, configured to generate a bias DC signal. The generated bias DC signal is applied to the conductive member of the substrate support unit 11. In one embodiment, the bias DC signal may also be applied to other electrodes, such as electrodes within an electrostatic chuck. In one embodiment, the bias DC signal may also be pulsed. Furthermore, the bias DC generation unit may be provided in conjunction with the RF power supply unit, or it may be provided in place of the second RF generation unit.

[0051] The exhaust system 40 can be connected, for example, to an exhaust port (gas outlet) located at the bottom of the plasma processing chamber 10. The exhaust system 40 may also include a pressure valve and a vacuum pump. The vacuum pump may also include a turbomolecular pump, a roughing pump, or a combination thereof.

[0052] The control device 50 processes computer-executable commands that cause the plasma processing apparatus 1 to perform the various processes described herein. The control device 50 can be configured to control various elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control device 50 may be included within the plasma processing apparatus 1. The control device 50 may also include, for example, a computer. The computer may include, for example, a processing unit (CPU), a storage unit, and a communication interface. The processing unit can be configured to perform various control actions based on programs stored in the storage unit. The storage unit may also include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or combinations thereof. The communication interface may also communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0053] <Antenna Structure>

[0054] Next, the structure of the plasma generation antenna 14 will be explained. Figure 2 This is a schematic cross-sectional view showing the structure of antenna 14. Figure 3 This is a schematic three-dimensional view showing the general structure of antenna 14.

[0055] like Figure 2 and Figure 3 As shown, antenna 14 is an inductively coupled plasma excitation antenna, and is an antenna assembly having a main coil 200 and a sub-coil assembly 210. The sub-coil assembly 210 is disposed around the gas inlet 13, surrounding the generally cylindrical gas inlet 13, and is located radially inside the main coil 200. That is, the sub-coil assembly 210 is positioned between the gas inlet 13 and the main coil 200. The main coil 200 is disposed around the gas inlet 13 and the sub-coil assembly 210. The shapes of the main coil 200 and the sub-coil assembly 210 are respectively formed to be approximately circular when viewed from above, as described later. Furthermore, the main coil 200 and the sub-coil assembly 210 are arranged in a concentric circle configuration.

[0056] Furthermore, the main coil 200 and the secondary coil assembly 210 are each supported by a support mechanism (not shown) in a manner that separates them from the dielectric window 10a above the dielectric window 10a. However, the secondary coil assembly 210 is not limited to being separate from the dielectric window 10a. For example, the secondary coil assembly 210 may also be in contact with the upper surface of the dielectric window 10a.

[0057] [Main Coil]

[0058] like Figure 3 As shown, the main coil 200 is formed into a roughly circular vortex shape with more than two loops, and is arranged such that the central axis of the main coil 200's shape is aligned with the Z-axis. In addition, the main coil 200 is a planar coil, and is arranged above the dielectric window 10a in a manner that is substantially parallel to the surface of the substrate W supported by the central region 111a.

[0059] The circuit constituting the main coil 200 is open at both ends. A first RF generator, connected to the midpoint or near the midpoint of the circuit constituting the main coil 200, supplies RF power to the main coil 200. The area near the midpoint of the circuit constituting the main coil 200 is grounded to a ground potential. The main coil 200 is configured to resonate at λ / 2 relative to the wavelength λ of the RF power supplied from the first RF generator. The voltage generated by the circuit constituting the main coil 200 is distributed such that it is minimum near the midpoint and maximum at both ends. Similarly, the current generated by the circuit constituting the main coil 200 is distributed such that it is maximum near the midpoint and minimum at both ends. The first RF generator, which supplies RF power to the main coil 200, can change both the frequency and the power.

[0060] [Secondary coil assembly]

[0061] Figure 4 This is a schematic perspective view showing the structure of the secondary coil assembly 210. Figure 5 This is a top view showing the general structure of the sub-coil assembly 210. Figure 6 This is a bottom view showing a general outline of the structure of the sub-coil assembly 210. Figure 7 and Figure 8 These are schematic side views showing the structure of the sub-coil assembly 210.

[0062] like Figure 4As shown, the sub-coil assembly 210 includes a first helical coil 211, a second helical coil 212, and connecting members 213 to 215. The first helical coil 211 and the second helical coil 212 each have a helical structure. The first helical coil 211 has one or more turns 211t, and the second helical coil 212 has one or more turns 212t. The turns 211t of the first helical coil 211 and the turns 212t of the second helical coil 212 are alternately arranged in the vertical direction when viewed from the side. The central axis of the outer shape of the first helical coil 211 and the central axis of the outer shape of the second helical coil 212 are both aligned with the Z-axis, and the first helical coil 211 and the second helical coil 212 are arranged on the same axis. The first helical coil 211 and the second helical coil 212 are each formed to be approximately circular when viewed from above. Furthermore, the diameters of all turns 211t of the first helical coil 211 are the same, and the diameters of all turns 212t of the second helical coil 212 are the same. Thus, the sub-coil assembly 210 has a generally cylindrical double-helix structure.

[0063] like Figure 7 and Figure 8 As shown, each turn 211t of the first helical coil 211 and each turn 212t of the second helical coil 212 are plate-shaped. For example, the width of each turn 211t and each turn 212t is more than twice the thickness. In order to allow more current to flow in the first helical coil 211 and the second helical coil 212, the cross-sectional area of ​​each turn 211t and 212t should be as large as possible. In addition, in the sub-coil assembly 210, the coupling with plasma is smaller in the upper part compared to the lower part. Therefore, in order to perform plasma processing efficiently, the height of the sub-coil assembly 210 should be as low as possible. That is, the thickness of each turn 211t and 212t should be as small as possible. In this case, it is preferable that each turn 211t and 212t is plate-shaped as in this embodiment to ensure that the cross-sectional area of ​​each turn 211t and 212t is small and the thickness is kept to a minimum.

[0064] like Figure 8 As shown, the distance D between the turns 211t of the first helical coil 211 and the turns 212t of the second helical coil 212, which are adjacent in the vertical direction, is 1 mm to 10 mm. Thus, since the distance D is 1 mm or more, dielectric breakdown of adjacent turns 211t and 212t in a vacuum atmosphere can be suppressed. Furthermore, since the distance D is 10 mm or less, plasma generation efficiency relative to the current can be maintained.

[0065] In the first helical coil 211, the connecting member 211s that connects the turns 211t extends in the vertical direction. In the second helical coil 212, the connecting member 212s that connects the turns 212t extends in the vertical direction. In this case, the manufacturing of the first helical coil 211 and the second helical coil 212 is easier, and the machining accuracy is also improved.

[0066] Furthermore, in the illustrated example, the number of turns (winding number) of the first helical coil 211 and the second helical coil 212 is 1.5 turns, but it is not limited to this and can be set to any number of turns, more than one turn. For example, the number of turns of the first helical coil 211 and the second helical coil 212 can also be two or more turns.

[0067] like Figure 5 As shown, the sub-coil assembly 210 has a first upper surface portion formed by the upper surface of the first helical coil 211 and a second upper surface portion formed by the upper surface of the second helical coil 212. The first upper surface portion includes a first upper terminal 211a, and the second upper surface portion includes a second upper terminal 212a. The first and second upper surface portions are arranged symmetrically to each other. That is, the first and second upper surface portions each have a generally semi-circular shape with a central angle of approximately 180 degrees.

[0068] In addition, such as Figure 6 As shown, the sub-coil assembly 210 has a first lower surface portion formed by the lower surface of the first helical coil 211 and a second lower surface portion formed by the lower surface of the second helical coil 212. The first lower surface portion includes a first lower terminal 211b, and the second lower surface portion includes a second lower terminal 212b. The first lower surface portion and the second lower surface portion are arranged symmetrically to each other. That is, the first lower surface portion and the second lower surface portion each have a generally semi-circular shape with a central angle of approximately 180 degrees.

[0069] like Figure 4 As shown, the first helical coil 211 has a first upper terminal 211a at its upper end and a first lower terminal 211b at its lower end. The second helical coil 212 has a second upper terminal 212a at its upper end and a second lower terminal 212b at its lower end. The first upper terminal 211a and the second upper terminal 212a are symmetrically positioned with respect to the center of the sub-coil assembly 210, that is, the central angle between adjacent upper terminals is approximately 180 degrees. The first lower terminal 211b and the second lower terminal 212b are also symmetrically positioned with respect to the center of the sub-coil assembly 210, that is, the central angle between adjacent lower terminals is approximately 180 degrees.

[0070] The first upper terminal 211a and the second upper terminal 212a are connected by a connecting member 213, which serves as a first conductive member. The connecting member 213 is formed in a roughly Y-shape when viewed from above. The connecting member 213 is grounded by connecting to a ground potential via one or more capacitors 220. That is, the first upper terminal 211a and the second upper terminal 212a are connected to a ground potential via a shared capacitor 220. The one or more capacitors 220 include variable capacitance capacitors. Furthermore, the one or more capacitors 220 are not limited to this embodiment and may also be capacitors with fixed capacitance. In addition, the one or more capacitors 220 may also include multiple capacitors having variable capacitance capacitors and / or fixed capacitance capacitors.

[0071] The first lower terminal 211b is grounded by connecting member 214, which serves as the second conductive member. The second lower terminal 212b is grounded by connecting member 215, which serves as the third conductive member. Thus, the sub-coil assembly 210 is not connected to the power supply unit 30, and therefore, RF power is not directly supplied to the sub-coil assembly 210. Furthermore, connecting member 214 and connecting member 215 can be provided independently as shown in the figure, or they can be integrated as a single unit.

[0072] like Figure 7 As shown, connecting member 214 extends from the first lower terminal 211b to a first height H. Connecting member 215 extends from the second lower terminal 212b to a first height H. That is, connecting members 214 and 215 have the same height. In addition, the first height H is higher than the heights of the first helical coil 211 and the second helical coil 212.

[0073] Furthermore, the arrangement of the first upper terminal 211a and the second upper terminal 212a, and the first lower terminal 211b and the second lower terminal 212b when viewed from above is not particularly limited. However, there is a large voltage difference between the first upper terminal 211a and the second upper terminal 212a, and between the first lower terminal 211b and the second lower terminal 212b, so it is preferable to maintain a certain degree of spacing in practical applications.

[0074] The secondary coil assembly 210 is inductively coupled to the primary coil 200, and a current flows in the secondary coil assembly 210 in a direction that eliminates the magnetic field generated by the current flowing in the primary coil 200. By controlling the capacitance of the capacitor 220, the direction and magnitude of the current flowing in the secondary coil assembly 210 can be controlled relative to the current flowing in the primary coil 200.

[0075] <The Function of Antennas>

[0076] In the antenna 14 configured as described above, a magnetic field is generated in the Z-axis direction by the current flowing in the main coil 200 and the current flowing in the sub-coil assembly 210. This magnetic field induces an electric field within the plasma processing chamber 10. The induced electric field within the plasma processing chamber 10 plasmaizes the processing gas supplied from the gas inlet 13 into the plasma processing chamber 10. Then, the ions and active species contained in the plasma are used to perform plasma processing such as etching and film deposition on the substrate W in the central region 111a.

[0077] <The Effect of Antennas>

[0078] Next, the effects of the antenna 14 configured as described above will be explained. In this embodiment, the antenna 14 provides the following four basic effects.

[0079] (1) It can reduce the electric field strength of the secondary coil assembly 210.

[0080] (2) It can improve the symmetry of the coil structure on the lower surface of the sub-coil assembly 210.

[0081] (3) It can reduce the electric field strength at the endpoints of the main coil 200.

[0082] (4) It can suppress the current flowing in the sub-coil assembly 210 (hereinafter referred to as "introduced current") to a smaller extent and improve the uniformity of plasma distribution with respect to the substrate W.

[0083] (1) The electric field of the secondary coil assembly 210 is reduced.

[0084] As before, for example, when the electric field strength of the antenna is high and the potential of the lower surface of the dielectric window is high, the plasma collides with the lower surface of the dielectric window, i.e., the surface on the side of the plasma processing space, causing wear and shortening the life of the component. This phenomenon can be measured as contamination of the top plate material. Similarly, in the region where the electric field strength affects the plasma, the plasma distribution on the wafer becomes non-uniform due to the change in plasma density caused by the electric field. Therefore, it is necessary to suppress the lower surface of the dielectric window to a lower potential.

[0085] In this embodiment, in the sub-coil assembly 210, the first lower terminal 211b of the first helical coil 211 is connected to the ground potential, and the second lower terminal 212b of the second helical coil 212 is connected to the ground potential. That is, the lower surface of the sub-coil assembly 210 is connected to the ground potential, thus reducing the electric field strength of the sub-coil assembly 210. Consequently, the lower surface of the dielectric window 10a can be suppressed to a lower potential, thereby suppressing the generation of contaminants. In addition, the plasma distribution with respect to the substrate W can be made uniform in the circumferential direction.

[0086] Furthermore, in the sub-coil assembly 210 of this embodiment, the lower surfaces of the first helical coil 211 and the second helical coil 212 are formed in a symmetrical shape with respect to the center of the sub-coil assembly 210. Therefore, the grounding potential of the lower surfaces can be made uniform in the circumferential direction in the sub-coil assembly 210.

[0087] (2) The symmetry of the lower surface of the secondary coil assembly 210 is improved.

[0088] In this embodiment, the sub-coil assembly 210 has a double-helix structure, and the lower surfaces of the first helical coil 211 and the second helical coil 212 are formed in a symmetrical shape with respect to the center of the sub-coil assembly 210. Therefore, in the sub-coil assembly 210, the current flowing in the circumferential direction can be made uniform, and the potential of the lower surface of the dielectric window 10a can be made uniform in the circumferential direction. As a result, the plasma distribution with respect to the substrate W can be made uniform in the circumferential direction.

[0089] The inventors conducted an experiment as follows: using the inner coil (single-loop coil) described in conventional Patent Document 1 as a comparative example, and considering the use of the secondary coil assembly 210 of this embodiment, the current flowing on the lower surface of the dielectric window 10a during plasma processing was investigated. This current was measured using a current distribution sensor for in-plane distribution measurement provided on the lower surface of the dielectric window 10a. In this experiment, the RF power supplied to the outer coil of the comparative example and the RF power supplied to the main coil 200 of this embodiment were set to be the same. As a result, the in-plane symmetry of the current distribution flowing in the dielectric window was not uniform compared to the comparative example, and the in-plane symmetry of the current distribution flowing in the dielectric window of this embodiment was made uniform.

[0090] Specifically, in this embodiment, the maximum standard deviation of the current value flowing through the dielectric window 10a in the circumferential direction can be suppressed to approximately 55% of that in the comparative example. Furthermore, in the sub-coil assembly 210 of this embodiment, the first helical coil 211 and the second helical coil 212 have 1.5 turns, but after investigating the case of 2.5 turns, it was found that the aforementioned maximum standard deviation can be further suppressed to approximately 53%.

[0091] Furthermore, after comparing the current values ​​in the above experiments, it was found that the current flowing through the dielectric window 10a in this embodiment can be suppressed to approximately 45% of that in the comparative example. In other words, according to this embodiment, compared with the conventional embodiment, the current value on the lower surface of the dielectric window 10a can be suppressed, and the introduced current flowing in the sub-coil assembly 210 can be made equal. As a result, the RF power supplied to the antenna 14 can be increased.

[0092] (3) The electric field at the endpoints of the main coil 200 decreases.

[0093] The inventors conducted the following experiment: using the inner coil described in conventional Patent Document 1 as a comparative example, and considering the use of the secondary coil assembly 210 of this embodiment, the energy of ions at the lower surface of the dielectric window 10a during plasma processing was investigated. In this experiment, comparisons were made between cases where an introduced current flows and cases where no introduced current flows for both the conventional inner coil and the secondary coil assembly 210 of this embodiment. Figure 9 This represents the experimental results of the comparative examples. Figure 10 This represents the experimental results of this implementation method. Figure 9 and Figure 10 In the diagram, the horizontal axis (Energy) represents the energy of the ions at the lower surface of the dielectric window 10a, and the vertical axis (Population) represents the number of ions reaching the lower surface of the dielectric window 10a. Furthermore, the measurement point for the energy and number of ions is the lower surface of the dielectric window located below the end of the outer coil in the comparative example, and in this embodiment, it is the lower surface of the dielectric window 10a located below the end of the main coil 200.

[0094] In the comparative example, refer to Figure 9 With and without an introduced current flowing in the inner coil, the peak value of the ion energy on the side with the higher energy (the point in the figure) hardly changes (the arrow in the figure). Therefore, it is impossible to reduce the electric field strength at the endpoints of the outer coil.

[0095] In addition, in this embodiment, reference is made to Figure 10When an introduced current flows in the secondary coil assembly 210, compared to the case where no introduced current flows, the peak value of the graph on the side with higher ion energy (the point in the figure) shifts in a manner that the ion energy decreases (the arrow in the figure). Therefore, when using the secondary coil assembly 210 of this embodiment, the electric field strength at the endpoints of the main coil 200 can be reduced.

[0096] Furthermore, the inventors conducted an experiment as follows: using the inner coil described in conventional Patent Document 1 as a comparative example, they investigated the amount of contamination during plasma processing when using the secondary coil assembly 210 of this embodiment. In both the comparative example and this embodiment, the material of the dielectric window 10a contains yttrium oxide. In this experiment, the amount of yttrium oxide contamination generated due to sputtering of the dielectric window 10a was measured. As a result, the amount of contamination per unit area (number of contaminants) in this embodiment was suppressed to approximately 20% of that in the comparative example. In other words, in this embodiment, the electric field strength at the endpoints of the main coil can be reduced, resulting in a reduction in the amount of contamination.

[0097] Furthermore, in this experiment, the outer coil of the comparative example and the main coil 200 of this embodiment were respectively arranged separately from the dielectric window 10a. Regarding this, after in-depth research, the inventors have learned that when the outer coil of the comparative example is arranged in contact with the dielectric window 10a, the amount of contamination per unit area increases compared to when the outer coil is separated. Therefore, based on this viewpoint, the main coil 200 of this embodiment is preferably arranged above it separately from the dielectric window 10a.

[0098] (4) Improve the uniformity of plasma distribution by using a smaller introduced current.

[0099] In this embodiment, the secondary coil assembly 210 has a double-helix structure, which increases the inductance of the secondary coil assembly 210. As a result, the introduced current flowing in the secondary coil assembly 210 can be suppressed to a smaller extent, and the uniformity of the plasma distribution with respect to the substrate W can be improved.

[0100] The inventors conducted the following experiment: using the inner coil described in conventional Patent Document 1 as a comparative example, and considering the use of the secondary coil assembly 210 of this embodiment, the current flowing in the inner coil and the secondary coil assembly 210 during plasma processing was investigated. In this experiment, the RF power supplied to the outer coil of the comparative example and the RF power supplied to the main coil 200 of this embodiment were set to be the same. As a result, compared with the current value of the inner coil of the comparative example, the current value of the secondary coil assembly 210 of this embodiment could be suppressed to a smaller value.

[0101] Furthermore, the inventors conducted the following experiment: using the inner coil described in conventional Patent Document 1 as a comparative example, and investigating the relationship between the introduced current during plasma processing and the ion distribution (ion distribution in the wafer radial direction) relative to the substrate W, specifically in the case using the sub-coil assembly 210 of this embodiment. In this experiment, the current value flowing in the substrate W was measured as the ion distribution. In this case, in the comparative example, even if the value of the introduced current flowing in the inner coil was varied, the ion distribution incident on the wafer remained almost unchanged. However, in this embodiment, when the value of the introduced current flowing in the sub-coil assembly 210 was varied, the amount of ions relative to the substrate W increased, and the ion distribution changed. Here, the magnitude of the ion current on the substrate W is related to the plasma density on the substrate W. Therefore, in this embodiment, by adjusting the value of the introduced current, the ion distribution relative to the substrate W, i.e., the plasma distribution, can be controlled. In other words, the range of plasma control for ensuring circumferential uniformity of the plasma distribution relative to the substrate W can be expanded, and the controllability of the plasma distribution can be improved.

[0102] Furthermore, the inventors conducted an experiment as follows: using the inner coil described in conventional Patent Document 1 as a comparative example, and investigating the relationship between the introduced current during plasma processing and the ion distribution relative to the substrate W when using the secondary coil assembly 210 of this embodiment. In this experiment, 3σ of the current flowing in the substrate W was calculated as the ion distribution. Therefore, in this experiment, the introduced current value with the minimum 3σ, i.e., the introduced current value with uniform ion distribution, became the optimal value. As a result, in this embodiment, the optimal introduced current value corresponding to the minimum 3σ can be suppressed to be less than that of the comparative example. In other words, in this embodiment, the circumferential uniformity of the plasma distribution relative to the substrate W can be improved using a smaller introduced current.

[0103] Furthermore, in the secondary coil assembly 210 of this embodiment, the number of turns (winding number) of the first helical coil 211 and the second helical coil 212 is 1.5 turns, but as described above, it can be set to any number of turns, more than one turn. In particular, based on the viewpoint of improving the uniformity of plasma distribution by utilizing a smaller introduced current, a larger number of turns is preferred, for example, 1.5 to 2.5 turns.

[0104] According to the above embodiments, the secondary coil assembly 210 has a double-helix structure, and the lower surface of the secondary coil assembly 210 is connected to the ground potential. Therefore, the electric field strength at the endpoints of the main coil 200 can be reduced, and the controllability of the plasma distribution can be improved. Consequently, the generation of contamination during plasma processing can be suppressed, and the uniformity of the plasma distribution with respect to the substrate W can be improved.

[0105] <Other Implementation Methods>

[0106] In the above embodiments, the sub-coil assembly 210 has a generally cylindrical double helical structure, but the structure of the sub-coil assembly 210 is not limited to this. Figures 11-13 This is a schematic perspective view showing the structure of the sub-coil assembly 210 in another embodiment.

[0107] like Figure 11 As shown, the sub-coil assembly 210 can also have a multi-helical structure. In addition to the first helical coil 211 and the second helical coil 212, the sub-coil assembly 210 also has a third helical coil 230. The third helical coil has at least one turn 230t. In side view, the turns 211t of the first helical coil 211, the turns 212t of the second helical coil 212, and the turns 230t of the third helical coil 230 are arranged sequentially in the vertical direction. The central axis of the outer shape of the third helical coil 230 is aligned with the Z-axis, and the first helical coil 211, the second helical coil 212, and the third helical coil 230 are arranged on the same axis. The third helical coil 230 is formed to be approximately circular in top view. Furthermore, the diameter of the third helical coil 230 in the vertical direction is the same as the diameter of the first helical coil 211 and the diameter of the second helical coil 212. Thus, the secondary coil assembly 210 has a generally cylindrical triple helix structure.

[0108] The upper surfaces of the first helical coil 211, the second helical coil 212, and the third helical coil 230 are symmetrical with respect to the center of the sub-coil assembly 210. That is, the upper surfaces of the first helical coil 211, the second helical coil 212, and the third helical coil 230 each have a generally circular arc shape with a central angle of approximately 120 degrees.

[0109] Furthermore, the lower surfaces of the first helical coil 211, the second helical coil 212, and the third helical coil 230 are formed in a symmetrical shape with respect to the center of the sub-coil assembly 210. That is, the lower surfaces of the first helical coil 211, the second helical coil 212, and the third helical coil 230 each have a generally circular arc shape with a central angle of approximately 120 degrees.

[0110] The third helical coil 230 has a third upper terminal 230a at its upper end and a third lower terminal 230b at its lower end. The first upper terminal 211a, the second upper terminal 212a, and the third upper terminal 230a are arranged symmetrically with respect to the center of the sub-coil assembly 210, that is, the central angle between adjacent upper terminals is approximately 120 degrees. The first lower terminal 211b, the second lower terminal 212b, and the third lower terminal 230b are also arranged symmetrically with respect to the center of the sub-coil assembly 210, that is, the central angle between adjacent lower terminals is approximately 120 degrees.

[0111] Although not shown in the diagram, the first upper terminal 211a, the second upper terminal 212a, and the third upper terminal 230a are connected by a connecting member 213. The connecting member 213 is grounded by means of a capacitor 220. That is, the first upper terminal 211a, the second upper terminal 212a, and the third upper terminal 230a are connected to the ground potential by means of a common capacitor 220.

[0112] The third lower terminal 230b is grounded by means of the connecting member 231 and is connected to the ground potential.

[0113] In this embodiment, the same effects as in the embodiments described above can be achieved. Specifically, the secondary coil assembly 210 has a triple helix structure, and its lower surface is connected to ground potential. Therefore, the electric field strength at the endpoints of the main coil 200 can be reduced, and the controllability of plasma distribution can be improved. Furthermore, while the secondary coil assembly 210 has a triple helix structure in this embodiment, it may also have a multi-helix structure with four or more helical configurations.

[0114] like Figure 12 As shown, the sub-coil assembly 210 can also have a generally conical shape. In this sub-coil assembly 210, at the same height, the diameter of the first helical coil 211 is the same as the diameter of the second helical coil 212. Furthermore, the diameters of each turn 211t of the first helical coil 211 and the diameters of each turn 212t of the second helical coil 212 differ in the vertical direction. Figure 12 In the example shown, the diameters of the first helical coil 211 and the second helical coil 212 gradually decrease as they move downwards. Furthermore, the lower surfaces of the first helical coil 211 and the second helical coil 212 are symmetrical with respect to the center of the sub-coil assembly 210.

[0115] In this embodiment, the same effects as in the embodiments described above can be achieved. That is, the secondary coil assembly 210 has a double-helix structure, and the lower surface of the secondary coil assembly 210 is connected to the ground potential, thereby reducing the electric field strength at the endpoints of the main coil 200 and improving the controllability of plasma distribution. Furthermore, in this embodiment, the secondary coil assembly 210 has a generally conical shape, but the shape of the secondary coil assembly 210 is not limited to this.

[0116] like Figure 13 As shown, in the sub-coil assembly 210, at the same height position, the diameters of the first helical coil 211 and the second helical coil 212 can be different. In the illustrated example, the diameter of the first helical coil 211 gradually increases from top to bottom. Conversely, the diameter of the second helical coil 212 gradually decreases from top to bottom. Furthermore, on the lower surface of the sub-coil assembly 210, the diameters of the first helical coil 211 and the second helical coil 212 are the same. Additionally, the lower surfaces of the first helical coil 211 and the second helical coil 212 are symmetrical with respect to the center of the sub-coil assembly 210.

[0117] In this embodiment, the same effects as in the above-described embodiment can also be achieved. That is, the secondary coil assembly 210 has a double-helix structure, and the lower surface of the secondary coil assembly 210 is connected to the ground potential. Therefore, the electric field strength at the endpoint of the main coil 200 can be reduced, and the controllability of plasma distribution can be improved.

[0118] <Other Implementation Methods>

[0119] In the above embodiments, the sub-coil assembly 210 is disposed radially inside the main coil 200, but it can also be disposed radially outside. Furthermore, the sub-coil assembly 210 can also be disposed on both the radially inside and radially outside sides of the main coil 200. That is, the antenna assembly can also have a first sub-coil assembly disposed radially inside the main coil 200 and a second helical coil assembly disposed radially outside. Additionally, the sub-coil assembly 210 can also be disposed below and / or above the main coil 200.

[0120] <Other Implementation Methods>

[0121] In the sub-coil assembly 210 of the above embodiment, the first upper terminal 211a of the first helical coil 211 and the second upper terminal 212a of the second helical coil 212 are connected to a common capacitor 220 via a connecting member 213, but they can also be connected to a separate capacitor (not shown). In this case, the first upper terminal 211a is connected to ground potential via a first capacitor (not shown), and the second upper terminal 212a is connected to ground potential via a second capacitor (not shown).

[0122] <Other Implementation Methods>

[0123] In the sub-coil assembly 210 of the above embodiment, the connecting member 213 is formed in a roughly Y-shape when viewed from above, but the planar shape of the connecting member 213 is not limited to this. For example, the planar shape of the connecting member 213 may also be roughly U-shaped. In addition, as described above, the sub-coil assembly 210 is inductively coupled to the main coil 200, and a current flows in the sub-coil assembly 210 in an orientation that eliminates the magnetic field generated by the current flowing in the main coil 200. Therefore, the connecting member 213 may also be configured to extend vertically upward from the first upper terminal 211a and the second lower terminal 212b to ensure a sufficient separation distance so as not to interfere with the magnetic field.

[0124] <Other Implementation Methods>

[0125] In the plasma processing apparatus 1 of the above embodiments, processing gas is supplied to the plasma processing space 10s from the gas inlet 13 provided in the central opening of the dielectric window 10a. However, in addition to providing the gas inlet 13, multiple injection ports that spray processing gas toward the Z-axis can also be provided in the circumferential direction along the side wall of the plasma processing chamber 10.

[0126] <Other Implementation Methods>

[0127] In the sub-coil assembly 210 of the above embodiments, the connecting member 213 is connected to the ground potential by means of the capacitor 220, and the connecting members 214 and 215 are connected to the ground potential, but the objects to which these connecting members 213 to 215 are connected are not limited to this. Figure 14 This is a schematic perspective view showing the structure of the sub-coil assembly 210 in another embodiment.

[0128] like Figure 14 As shown, the secondary coil assembly 210 is disposed within the conductive housing 250. The conductive housing 250 is located in the upper part or above the plasma processing chamber 10. The conductive housing 250 is connected to the ground potential. The conductive housing 250 has a top plate 251 and side walls 252. Furthermore, in Figure 14 In the example, to make the technology easy to understand, the left and right sidewalls 252 of the sub-coil assembly 210 are shown in the illustration, while the sidewalls 252 of the front and rear surfaces of the sub-coil assembly 210 are omitted.

[0129] The connecting members 213 to 215 of the secondary coil assembly 210 are respectively connected to the top plate 251 of the conductive housing 250. That is, the connecting members 213 to 215 are connected to the conductive housing 250 at a position higher than the uppermost parts of the first helical coil 211 and the second helical coil 212. The connecting member 213 is connected to the top plate 251 by means of a capacitor 253. In addition, the connecting members 214 and 215 may also be connected to the side wall 252 at a position higher than the uppermost parts of the first helical coil 211 and the second helical coil 212.

[0130] In this case, the secondary coil assembly 210 is connected to the ground potential via the conductive housing 250, which can be used as a current distribution mechanism.

[0131] <Other Implementation Methods>

[0132] Next, the structure of the antenna 14 in another embodiment will be described. In the plasma processing apparatus 1 of the above embodiment, the main coil 200 disposed on the radially outer side is connected to the RF potential, and the secondary coil assembly 210 disposed on the radially inner side is connected to the ground potential. In contrast, in other embodiments, the main coil assembly disposed on the radially inner side is connected to the RF potential, and at least one secondary coil disposed on the radially outer side is connected to the ground potential.

[0133] Figures 15-20 This is a schematic perspective view showing the structure of the antenna 14 in other embodiments, specifically examples 1 to 6 of the other embodiments. Figures 15-20 As shown, antenna 14 is an antenna assembly having a main coil assembly 300 and at least one secondary coil (a first secondary coil 310 and a second secondary coil 320).

[0134] The main coil assembly 300 is provided in common in Examples 1 to 6. The main coil assembly 300 has the same structure as the secondary coil assembly 210 in the above embodiments. That is, the main coil assembly 300 has a first helical coil 301, a second helical coil 302, and connecting members 303 to 305. These first helical coils 301, second helical coils 302, and connecting members 303 to 305 correspond to the first helical coil 211, second helical coil 212, and connecting members 213 to 215 in the above embodiments, respectively.

[0135] The first helical coil 301 has one or more turns 301t, and the second helical coil 302 has one or more turns 302t. The turns 301t of the first helical coil 301 and the turns 302t of the second helical coil 302 are arranged alternately in the vertical direction when viewed from the side.

[0136] The first helical coil 301 has a first upper terminal 301a at its upper end and a first lower terminal 301b at its lower end. The second helical coil 302 has a second upper terminal 302a at its upper end and a second lower terminal 302b at its lower end. The first upper terminal 301a and the second upper terminal 302a are connected by a connecting member 303, which serves as a first conductive member. The connecting member 303 is connected to the first RF generation unit of the RF power supply unit, i.e., connected to the RF potential. The first lower terminal 301b is grounded by connecting member 304, which serves as a second conductive member. The second lower terminal 302b is grounded by connecting member 305, which serves as a third conductive member. Furthermore, the connecting members 304 and 305 can be provided independently as shown in the figure, or they can be provided as a single unit.

[0137] Furthermore, the other structures of the first helical coil 301 and the second helical coil 302 are the same as those of the first helical coil 211 and the second helical coil 212 in the above embodiment, so the description is omitted.

[0138] As described above, in any of the examples 1 to 6, the main coil assembly 300 has the same structure as the secondary coil assembly 210 of the above embodiment, and thus can enjoy the same effects as those described in (1) to (4) of this embodiment.

[0139] At least one secondary coil (secondary coil 310, 320) is arranged radially outside the main coil assembly 300, surrounding it. The secondary coils 310 and 320 have different structures in Examples 1 through 6. These Examples 1 through 6 will be described below. Furthermore, in Figures 15-20 In the example shown, secondary coils 310 and 320 are represented by lines to make the technology easy to understand, but they are actually coils with arbitrary cross-sectional shapes.

[0140] [Example of another implementation]

[0141] In the first case, such as Figure 15 As shown, at least one secondary coil includes a first secondary coil 310. The first secondary coil 310 is a planar coil formed in a generally circular shape. The central axis of the outer shape of the first secondary coil 310 is aligned with the Z-axis and is disposed on the same axis as the main coil assembly 300.

[0142] The first auxiliary coil 310 has a first terminal 310a and a second terminal 310b. The first terminal 310a and the second terminal 310b are connected by a capacitor 330. The capacitor 330 is a variable capacitance capacitor.

[0143] The first secondary coil 310 is inductively coupled to the main coil assembly 300, and a current flows in the first secondary coil 310 in an orientation that eliminates the magnetic field generated by the current flowing in the main coil assembly 300. By controlling the capacitance of the capacitor 330, the orientation and magnitude of the current flowing in the first secondary coil 310 can be controlled relative to the current flowing in the main coil assembly 300.

[0144] [Second example of another implementation]

[0145] In the second case, such as Figure 16 As shown, at least one secondary coil includes a first secondary coil 310. The first secondary coil 310 has the same structure as in the first example, having a first terminal 310a and a second terminal 310b.

[0146] Terminal 310a is connected to ground potential via capacitor 331. Capacitor 331 is a variable capacitance capacitor. Terminal 310b is connected to ground potential via capacitor 332. Capacitor 332 is a fixed capacitance capacitor. Alternatively, capacitor 332 can also be a variable capacitance capacitor. Furthermore, capacitor 332 is not essential and can be omitted.

[0147] [A third example of another implementation]

[0148] In the third case, such as Figure 17 As shown, at least one secondary coil includes a first secondary coil 310 and a second secondary coil 320. The first secondary coil 310 has the same structure as in the first example, having a first terminal 310a and a second terminal 310b. The first terminal 310a and the second terminal 310b are connected by a capacitor 330.

[0149] The second sub-coil 320 is a planar coil formed in a generally circular shape. The second sub-coil 320 has the same shape and diameter as the first sub-coil 310. The central axis of the outer shape of the second sub-coil 320 is aligned with the Z-axis and is located on the same axis as the first sub-coil 310.

[0150] The second auxiliary coil 320 has a third terminal 320a and a fourth terminal 320b. The third terminal 320a and the fourth terminal 320b are connected by a capacitor 333. The capacitor 333 is a variable capacitance capacitor.

[0151] Similar to the first secondary coil 310, the second secondary coil 320 is inductively coupled to the main coil assembly 300, and a current flows in the second secondary coil 320 in an orientation that eliminates the magnetic field generated by the current flowing in the main coil assembly 300. By controlling the capacitance of the capacitor 333, the orientation and magnitude of the current flowing in the second secondary coil 320 can be controlled relative to the current flowing in the main coil assembly 300.

[0152] The first sub-coil 310 has a first coil portion 311 and a second coil portion 312. The first coil portion 311 is a semi-circular portion extending from the first terminal 310a to the midpoint of the first sub-coil 310. The second coil portion 312 is a semi-circular portion extending from the second terminal 310b to the midpoint of the first sub-coil 310. The second sub-coil 320 has a third coil portion 321 and a fourth coil portion 322. The third coil portion 321 is a semi-circular portion extending from the third terminal 320a to the midpoint of the second sub-coil 320. The fourth coil portion 322 is a semi-circular portion extending from the fourth terminal 320b to the midpoint of the second sub-coil 320. The first coil portion 311 is disposed radially outward of the third coil portion 321. The second coil portion 312 is disposed radially inward of the fourth coil portion 322.

[0153] The first and second terminals 310a and 310b of the first sub-coil 310, and the third and fourth terminals 320a and 320b of the second sub-coil 320, are arranged symmetrically with respect to the center (at a central angle of approximately 180 degrees). That is, the first sub-coil 310 (first terminals 310a and 310b) and the second sub-coil 320 (third terminals 320a and 320b) are arranged symmetrically. Furthermore, the first and second sub-coils 310 and 320 have the same size and shape, and they are arranged in a nested configuration at equal intervals.

[0154] Here, terminals 310a and 310b, 320a and 420b form a singularity, and the current may deflect towards this singularity. In this regard, if the singularities are arranged symmetrically as described above, the deflection of the current flowing in the first sub-coil 310 and the second sub-coil 320 can be suppressed, and the circumferential uniformity of the magnetic field strength can be improved.

[0155] [Example 4 of other implementation methods]

[0156] In the fourth case, such as Figure 18 As shown, at least one secondary coil includes a first secondary coil 310 and a second secondary coil 320. Similar to the third example, the first secondary coil 310 has a first terminal 310a and a second terminal 310b, and the second secondary coil 320 has a third terminal 320a and a fourth terminal 320b. Furthermore, similar to the third example, the first terminal 310a and the second terminal 310b are symmetrically arranged with respect to the third terminal 320a and the fourth terminal 320b.

[0157] The second terminal 310b and the third terminal 320a are respectively connected to the first conductive plate 340. The first conductive plate 340 has a generally annular shape when viewed from above. The first terminal 310a and the fourth terminal 320b are respectively connected to the second conductive plate 341. The second conductive plate 341 has a generally annular shape when viewed from above and is disposed radially outside the first conductive plate 340. The central axis of the outer shape of the first conductive plate 340 and the central axis of the outer shape of the second conductive plate 341 are both aligned with the Z-axis and disposed on the same axis. Furthermore, the planar shapes of the first conductive plate 340 and the second conductive plate 341 are not limited to this example.

[0158] The first conductive plate 340 is connected to ground potential via capacitor 342. Capacitor 342 is a variable capacitance capacitor. The second conductive plate 341 is connected to ground potential via capacitor 343. Capacitor 343 is a fixed capacitance capacitor. Alternatively, capacitor 343 can also be a variable capacitance capacitor. Furthermore, capacitor 343 is not essential and can be omitted.

[0159] The current flowing in the first secondary coil 310 is distributed to the first conductive plate 340 and the second conductive plate 341. Similarly, the current flowing in the second secondary coil 320 is also distributed to the first conductive plate 340 and the second conductive plate 341. Thus, the distributed current flows circumferentially in the first conductive plate 340 and the second conductive plate 341, thereby suppressing circumferential current deviation and further improving the circumferential uniformity of the magnetic field strength.

[0160] [Example 5 of other implementation methods]

[0161] In case 5, such as Figure 19 As shown, at least one secondary coil includes a first secondary coil 310 and a second secondary coil 320. Similar to the third example, the first secondary coil 310 has a first terminal 310a and a second terminal 310b, and the second secondary coil 320 has a third terminal 320a and a fourth terminal 320b.

[0162] In the first sub-coil 310, terminal 310a is open. Terminal 310b is connected to ground potential via capacitor 350. Capacitor 350 is a variable capacitance capacitor. In the second sub-coil 320, terminal 320a is connected to ground potential via capacitor 351. Capacitor 351 is a variable capacitance capacitor. Terminal 320b is open.

[0163] Since the first terminal 310a of the first sub-coil 310 is an open terminal, the voltage rises at the first terminal 310a, making plasma ignition easier. Similarly, since the fourth terminal 320b of the second sub-coil 320 is an open terminal, the voltage rises at the fourth terminal 320b, making plasma ignition easier.

[0164] Furthermore, the second terminal 310b of the first sub-coil 310 and the third terminal 320a of the second sub-coil 320 are arranged symmetrically with respect to the center. Therefore, the deviation of the current flowing in the first sub-coil 310 and the second sub-coil 320 can be suppressed, and the circumferential uniformity of the magnetic field strength can be improved.

[0165] [Sixth example of another implementation]

[0166] In case 6, such as Figure 20 As shown, at least one secondary coil includes a first secondary coil 310 and a second secondary coil 320. Similar to Example 5, the first secondary coil 310 has a first terminal 310a and a second terminal 310b, and the second secondary coil 320 has a third terminal 320a and a fourth terminal 320b. Furthermore, similar to Example 5, the first terminal 310a and the fourth terminal 320b are open terminals, and the second terminal 310b and the third terminal 320a are symmetrically arranged.

[0167] Terminal 310b and terminal 320a are respectively connected to conductive plate 360. Conductive plate 360 ​​has a generally annular shape when viewed from above. The central axis of conductive plate 360 ​​is aligned with the Z-axis and is coaxial with the main coil assembly 300. Conductive plate 360 ​​is connected to ground potential via capacitor 361. Capacitor 361 is a variable capacitance capacitor.

[0168] In the sixth example, the same effect as in the fifth example can be achieved. Moreover, the number of expensive variable capacitance capacitors can be reduced, thus lowering the cost of the device.

[0169] Furthermore, in Examples 1 to 6 of the other embodiments described above, the main coil assembly 300 can also be connected to the first RF generation unit of the RF power supply unit via a conductive plate. Hereinafter, as... Figure 21 As shown, the case where the conductive plate 370 is provided in the first example will be explained, and the same applies to the second to fifth examples.

[0170] like Figure 21As shown, the connecting member 303 of the main coil assembly 300 is connected to the first RF generation section of the RF power supply section via a conductive plate 370. The conductive plate 370 is arranged around the central gas injection section in a generally cylindrical shape surrounding the gas inlet section 13. The conductive plate 370 has a generally circular shape when viewed from above and has a central opening 371. Furthermore, the shape of the conductive plate 370 is not particularly limited, and for example, it can also be rectangular.

[0171] In this case, when RF power is supplied from the first RF generation unit, current flows circumferentially in the conductive plate 370. Therefore, the circumferential uniformity of the magnetic field strength can be further improved.

[0172] <Other Implementation Methods>

[0173] Next, the structure of the antenna 14 in other embodiments will be described. In the plasma processing apparatus 1 of the above embodiments, the main coil 200 or the main coil assembly 300 is connected to the RF potential, and the secondary coil assembly 210 or the secondary coils 310, 320 are connected to the ground potential. In contrast, in other embodiments, both the main coil assembly and the secondary coil are connected to the RF potential. Figure 22 This is a schematic perspective view showing the structure of antenna 14 in other embodiments.

[0174] like Figure 22 As shown, antenna 14 is an antenna assembly having a main coil assembly 300, a first sub-coil 310, and a second sub-coil 320. The main coil assembly 300 has the same structure as the main coil assembly 300 in the first to sixth examples of the other embodiments described above. Similar to example 3, the first sub-coil 310 has a first terminal 310a and a second terminal 310b, and the second sub-coil 320 has a third terminal 320a and a fourth terminal 320b. Furthermore, similar to example 3, the first terminal 310a and the second terminal 310b are arranged symmetrically with the third terminal 320a and the fourth terminal 320b.

[0175] In the first sub-coil 310, the first terminal 310a is connected to ground potential via a capacitor 380. The capacitor 380 is a variable capacitance capacitor. Additionally, the second terminal 310b is connected to the first RF generation unit of the RF power supply section. In the second sub-coil 320, the third terminal 320a is connected to the first RF generation unit of the RF power supply section. Additionally, the fourth terminal 320b is connected to ground potential via a capacitor 381. The capacitor 381 is a variable capacitance capacitor. Furthermore, the first RF generation unit connected to the second terminal 310b and the third terminal 320a is shared with the first RF generation unit connected to the connecting member 303 of the main coil assembly 300. Alternatively, the first terminal 310a and the fourth terminal 320b can also be connected to a shared conductive plate (not shown) and connected to ground potential via a shared capacitor (not shown).

[0176] In this case, the first sub-coil 310 and the second sub-coil 320 are not inductively coupled to the main coil assembly 300. Thus, RF power is supplied to the main coil assembly 300 and current flows there, and RF power is also supplied to the first sub-coil 310 and the second sub-coil 320 and current flows there.

[0177] Furthermore, in this embodiment, the main coil assembly 300, the first sub-coil 310, and the second sub-coil 320 are connected to a common RF power supply unit, but they can also be connected to separate RF power supply units.

[0178] It should be considered that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The above embodiments may also be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

Claims

1. A plasma processing apparatus, wherein, The plasma processing device has the following features: Plasma processing chamber; The main coil is located at the upper part or above the plasma processing chamber; An RF power supply unit, configured to supply RF power to the main coil; and A secondary coil assembly is disposed radially inside or radially outside the main coil. The secondary coil assembly is inductively coupled to the main coil but not connected to the RF power supply unit. The secondary coil assembly includes a first helical coil having one or more turns and a second helical coil having one or more turns. The turns of the first helical coil and the turns of the second helical coil are alternately arranged in the vertical direction. The first helical coil has a first upper terminal at its upper end and a first lower terminal at its lower end. The first upper terminal is connected to ground potential via one or more capacitors, and the first lower terminal is connected to ground potential. The second helical coil has a second upper terminal at its upper end and a second lower terminal at its lower end. The second upper terminal is connected to ground potential via the one or more capacitors, and the second lower terminal is connected to ground potential.

2. The plasma processing apparatus according to claim 1, wherein, The main coil is configured such that both ends of the circuit constituting the main coil are open, and power is supplied from the RF power supply unit to the midpoint or near the midpoint of the circuit. The circuit is grounded near the midpoint, and the main coil resonates at half the wavelength of the RF power supplied from the RF power supply unit.

3. The plasma processing apparatus according to claim 1 or 2, wherein, The plasma processing apparatus has a gas inlet located at the upper center of the plasma processing chamber, configured to introduce processing gas into the plasma processing chamber. The secondary coil assembly is located between the gas inlet and the main coil.

4. The plasma processing apparatus according to claim 1 or 2, wherein, The one or more capacitors include variable capacitance capacitors.

5. The plasma processing apparatus according to claim 1 or 2, wherein, The second upper terminal is connected to ground potential via one or more capacitors.

6. The plasma processing apparatus according to claim 1 or 2, wherein, The lower surface of the sub-coil assembly has a first lower surface portion formed by the lower surface of the first helical coil and a second lower surface portion formed by the lower surface of the second helical coil, the first lower surface portion and the second lower surface portion being symmetrically arranged to each other.

7. The plasma processing apparatus according to claim 1 or 2, wherein, The upper surface of the sub-coil assembly has a first upper surface portion formed by the upper surface of the first helical coil and a second upper surface portion formed by the upper surface of the second helical coil, the first upper surface portion and the second upper surface portion being symmetrically arranged to each other.

8. The plasma processing apparatus according to claim 1 or 2, wherein, The diameters of all turns of the first helical coil are the same, and the diameters of all turns of the second helical coil are the same.

9. The plasma processing apparatus according to claim 1 or 2, wherein, The secondary coil assembly includes a third helical coil having one or more turns. The turns of the first helical coil, the turns of the second helical coil, and the turns of the third helical coil are arranged sequentially in the vertical direction. The third helical coil has a third upper terminal at the upper end and a third lower terminal at the lower end. The third upper terminal is connected to the ground potential via one or more capacitors, and the third lower terminal is connected to the ground potential.

10. The plasma processing apparatus according to claim 1 or 2, wherein, Each turn of the first spiral coil and each turn of the second spiral coil are plate-shaped.

11. The plasma processing apparatus according to claim 1 or 2, wherein, The interval between the turns of the first spiral coil and the turns of the second spiral coil adjacent to each other in the vertical direction is 1 mm to 10 mm.

12. The plasma processing apparatus according to claim 1 or 2, wherein, The connecting member that connects the turns in the first helical coil extends in the vertical direction. The connecting member that connects the turns in the second helical coil extends in the vertical direction.

13. An antenna assembly used in a plasma processing apparatus, wherein, The antenna assembly has: The main coil has a connection point for connection to the RF power supply and is configured to be connected to the RF power supply; and A secondary coil assembly is disposed radially inside or radially outside the main coil. The secondary coil assembly is inductively coupled to the main coil but not connected to the RF power supply unit. The secondary coil assembly includes a first helical coil having one or more turns and a second helical coil having one or more turns. The turns of the first helical coil and the turns of the second helical coil are alternately arranged in the vertical direction. The first helical coil has a first upper terminal at its upper end and a first lower terminal at its lower end. The first upper terminal is connected to ground potential via one or more capacitors, and the first lower terminal is connected to ground potential. The second helical coil has a second upper terminal at its upper end and a second lower terminal at its lower end. The second upper terminal is connected to ground potential via the one or more capacitors, and the second lower terminal is connected to ground potential.

14. The antenna assembly according to claim 13, wherein, The one or more capacitors mentioned are variable capacitance capacitors.

15. The antenna assembly according to claim 13 or 14, wherein, The second upper terminal is connected to ground potential via one or more capacitors.

16. The antenna assembly according to claim 13 or 14, wherein, The lower surface of the sub-coil assembly has a first lower surface portion formed by the lower surface of the first helical coil and a second lower surface portion formed by the lower surface of the second helical coil, the first lower surface portion and the second lower surface portion being symmetrically arranged to each other.

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