Impedance matching device and RF power module

Abstract

Impedance matching device (111) comprising a housing (1) in which a separation is provided within the housing (1) to divide the housing (1) into the following parts: - RF compartment (2) comprising RF circuit components; - drive compartment (3) comprising drive components; - low voltage compartment (4) comprising low voltage components, such as control components.

Description

The present invention relates to an impedance matching device and a power module comprising such an impedance matching device. Such a device and module are used, in particular, in plasma applications, such as plasma processing setups, especially for processing thin films, e.g., deposition or etching. Such processing steps are carried out, for example, in semiconductor manufacturing. Technical background: In a typical RF discharge plasma generation system, the output impedance of an RF power supply is usually 50 ohms, while the equivalent impedance of the plasma reaction chamber is typically not 50 ohms and also varies under different process conditions. RF here refers to frequencies above 1 MHz, and specifically below 300 MHz. Transmission line theory indicates that if the output impedance of the RF power supply differs from the load impedance (i.e., the equivalent impedance of the plasma reaction chamber), the output power of the RF power supply is at least partially lost, and the output efficiency cannot be maximized. This can lead to energy waste and damage to the RF power supply itself. Safety problems such as fire caused by excessive local heat can also occur.Since the magnitude of the load impedance is related to the plasma generation process conditions, when using an inductively coupled plasma source, it is necessary to add an impedance matching device that can automatically adjust the load impedance between the RF power supply and the plasma reaction chamber. The impedance matching device can change the actual value of a parameter-adjustable component, such as an adjustable capacitor, via the sensor and the sensor and control system integrated into the impedance matching system, according to the actual impedance of the plasma reaction chamber under different process conditions, so that the load impedance corresponds to 50 ohms. Implement impedance matching to avoid the problems mentioned above. 1. The impedance matching device includes high-voltage and low-voltage components that are sensitive to electromagnetic interference (EMI) during operation. This can lead to unstable operation of the equipment and even damage to the components, significantly compromising the quality of the impedance matching device. 2. With technological advancements and improved levels of integration, the impedance matching device must achieve the necessary heat dissipation within a small volume. This places higher demands on the heat dissipation efficiency of the impedance matching device, requiring it to achieve better heat dissipation within the limited space available to fit the system layout of this column. Referring to the technical scheme disclosed by CN217470562U, an adaptation structure is specified which divides the high and low voltage areas through the plate body (38) to meet the need for anti-electromagnetic interference and applies the heat dissipation form of an independent fan to ensure the heat dissipation efficiency of the high voltage area. The present application provides an impedance matching device consisting of a housing with a partition inside the housing, which is used to divide the housing into the following areas: RF compartment for accommodating RF circuit components; drive compartment, which houses the driver components of the RF circuit; low-voltage compartment for accommodating devices such as printed circuit boards used to control systems. In the second aspect, the present application provides an RF power module, including the aforementioned impedance matching device, an RF power supply, and an RF cable. The RF power supply has an output terminal that is connected via the RF cable to the RF input terminal of the impedance matching device. The present invention, through the aforementioned technical method, has the following advantageous effects compared to the prior art: • The separation of the three compartments inside the impedance matching device by the partition can effectively prevent electromagnetic interference between different module components. • The electromagnetic shielding effect is further enhanced by the use of partitions and housings made of metal materials. • The real and imaginary parts of the impedance are each adjusted by two capacitors to more accurately match the impedance. • The bias indicator enables a DC voltage measurement for the output terminal of this impedance matching device. In one aspect, the impedance matching device has a housing in which a separation is provided within the housing to divide the housing into the following parts: RF space, comprising RF circuit components; drive space, comprising drive components; low voltage space, comprising low voltage components, such as control components. In this way, the aforementioned task can be solved particularly well. In one aspect, the following RF circuit components are arranged in the RF space as follows: a first variable capacitor, a second variable capacitor, and a fixed capacitor, with the central axis of one or both of the variable capacitors lying parallel to the central axis of the fixed capacitor. This method is particularly effective in solving the aforementioned task. "Variable" means that the value of the corresponding component, e.g., the capacitance of a capacitor, can be adjusted during operation, for example, using a rotary device that can be driven by a motor. In this context, "fixed" means that the value of the corresponding component, e.g. the capacitance value of a capacitor or the inductance of an inductor, is not adjustable during operation, i.e., it is fixed. In one aspect, the following RF circuit component is arranged in the RF space as follows: an inductor coil, wherein the inductor coil is arranged in a spiral. This method is particularly effective for solving the aforementioned problem. "Spiral" can refer to a centric spiral, for example, one arranged in a plane. Preferably, "spiral" here refers to a helical shape. In one aspect, the central axis of the inductor coil is perpendicular to the central axis of the fixed capacitor. This method is particularly effective in solving the aforementioned problem. In one aspect, the end of the variable capacitors is electrically connected to one end of the inductor coil. This method is particularly effective in solving the aforementioned task. In one aspect, the housing contains a fixed capacitor, a grounding inductor, an RF input module, and an RF output module. This method is particularly effective in solving the aforementioned task. In one aspect, one end of one, or more specifically both, variable capacitors is electrically connected to one end of the fixed capacitor and subsequently electrically connected to the RF output module. This method is particularly effective in solving the aforementioned task. In one aspect, one end of the first variable capacitor is electrically connected to the RF input module. This method is particularly effective in solving the aforementioned problem. In one aspect, one end of the second variable capacitor is electrically connected to the grounding inductor. This method is particularly effective in solving the aforementioned task. In one aspect, one end of the grounding inductor is electrically connected to the housing. In this way, the aforementioned task can be solved particularly well. In one aspect, one, or in particular both, variable capacitors are connected to a partition wall, in particular screwed in place, by means of an insulating connector. This method is particularly effective in solving the aforementioned task. In one aspect, an RF shield is attached to the position of the RF output module, corresponding to the housing, and the signal line of the RF output module is at least partially routed within the RF shield. In this way, the aforementioned task can be solved particularly well. In one aspect, the drive unit comprises: a first motor connected to the first variable capacitor via a one-to-one gearbox, and a transmission shaft that linearly connects the first motor to the first variable capacitor. In this way, the aforementioned task can be solved particularly well. In one aspect, the drive unit comprises: a second motor connected to the second variable capacitor via a one-to-one gearbox, and a transmission link that linearly connects the second motor to the second variable capacitor. This method is particularly effective in solving the aforementioned task. In one aspect, the transmission connection is implemented using a needle-like connector between the motor and the variable capacitor, as well as a coupling that is electrically insulating. In this way, the aforementioned task can be solved particularly well. In one aspect, an RF fan is attached to the position of one end of the inductor coil corresponding to the housing, and an RF heat dissipation opening is attached to the opposite side of the RF fan, also corresponding to the housing. In this way, the aforementioned task can be solved particularly well. In one aspect, the low-voltage compartment borders both the drive compartment and the RF compartment, and a partition wall is provided at the position between the low-voltage compartment and the drive compartment, which has an opening for the circuit connection between the two compartments. In this way, the aforementioned task can be solved particularly well. In one aspect, the RF partition is equipped with an internal heat dissipation opening in the position corresponding to the top of a motor. In this way, the aforementioned task can be solved particularly well. In one aspect, a low-voltage fan is mounted at the position between the low-voltage partition of the passenger compartment and the low-voltage compartment, and another low-voltage fan is positioned in the engine compartment to direct the airflow between the low-voltage compartment and the engine compartment. In this way, the aforementioned task can be solved particularly well. In one aspect, the housing is equipped with a housing heat dissipation opening at the position of one end of the motor, corresponding to the motor. This method is particularly effective in solving the aforementioned task. In one aspect, the housing is equipped with a cooling inlet and a cooling outlet, and a cooling fluid pipe made of insulating material is installed in the RF compartment. In this way, the aforementioned task can be solved particularly well. In one aspect, a coolant distribution channel is attached at the position of the RF output module, and the inductor coil is designed in the form of a hollow conductor, so that a coolant can flow through the coolant distribution channel and from the inside through the inductor coil. In this way, the aforementioned task can be solved particularly well. In one aspect, a preload rod is provided, wherein the end of the preload rod is attached to the housing, and wherein the housing is provided with a preload shield at the position corresponding to the end of the preload rod. This method is particularly effective in solving the aforementioned task. In one aspect, the partitions and the housing are made of metal materials. In this way, the aforementioned problem can be solved particularly well. In one aspect, an RF power module comprises: an RF power supply, an RF cable, and an impedance matching device according to one of the preceding claims, wherein the RF power supply includes an output terminal and the output terminal is connected to the input terminal of the impedance matching device via the RF cable. In this way, the aforementioned problem can be solved particularly well. The figures illustrate the development using exemplary embodiments. Fig. 1 is the overall schematic of the impedance matching device for the respective application; Fig. 2 is a schematic diagram of the RF spatial components of the impedance matching device for the present application; Fig. 3 is a schematic diagram of the variable capacitor connection of the impedance matching device for the present application; Fig.Figure 4 is the overall diagram of the fixed capacitor terminal of the impedance matching device of the present application; Figure 5 is a schematic diagram of the linear inductor of the impedance matching device of the present application; Figure 6 is a schematic diagram of the variable capacitor drive of the impedance matching device of the present application; Figure 7 is a schematic diagram of the partitioning of the impedance matching device of the present application; Figure 8 is a schematic diagram of the low-voltage compartment of the impedance matching device of the present application; Figure 9 is a schematic diagram of the housing of the impedance matching device of the present application; Figure 10 is a schematic diagram of the interlock switch of the impedance matching device of the present application; Figure 11 is a schematic diagram of the inductor coil of the water-cooling circuit of the impedance matching device; FigureFigure 12 is a schematic diagram of the water cooling scheme of the impedance matching device of the respective application. The present application shows an impedance matching device 111 for use in the plasma field for the function of realizing the impedance matching between power supply and plasma equipment. As shown in Fig. 1, an embodiment of the present technical scheme includes a housing 1 which divides the space into three functional spaces by means of an RF partition 11, a stepped partition 12 and a low-voltage partition 13 as shown in Fig. 7, namely RF space 2, drive space 3 and low-voltage space 4. As shown in Fig. 1 and Fig. 2, in each embodiment of the present application, the RF chamber 2 has two variable capacitors installed in the housing 1, namely a first variable capacitor 200 and a second variable capacitor 201. The RF chamber 2 further includes an inductor coil 210, a fixed capacitor 202, and a grounding inductor 211 on the underside of the housing 1. The RF chamber 2 also includes an RF input module 22 installed on the side wall of the housing 1 near a variable capacitor 201, and an RF output module 23 located on the side wall of the housing 1 away from the position of the variable capacitor 200. Finally, the RF chamber 2 includes a biasing bar 25 installed on the side wall of the housing 1 relative to the RF input module 22.Furthermore, the RF array 2 has a first insulating connector 260 and a second insulating connector 260, both of which are mounted on the RF isolation plate 11. In this design, the inductor coil 210 uses a spiral coil, which mainly serves to provide the high inductance value required by the matching scheme. Other designs can be selected using various methods, such as a linear inductor 212 when a low inductance value is required, as shown in Fig. 5. As shown in Figs. 2-4, in each embodiment of the present application, the central axes of the variable capacitor 200 and the variable capacitor 201 are arranged parallel to each other, and the end faces of the variable capacitor 200 and the variable capacitor 201 are connected to one end of the inductor coil 210. The central axis of the inductor coil 210 is arranged perpendicular to the central axis of the variable capacitor 200. The inductor coil 210 is electrically connected to the variable capacitor 200 via a conductive connector 241 at one end of the fixed capacitor 202 and extends to the copper block 230 of the RF output module 23. By the above method, the components of each embodiment of the present application are the variable capacitor 200, variable capacitor 201, fixed capacitor 202, inductor coil 210, and grounding inductor 211. Among these, variable capacitors 200 and 201 are variable capacitors whose capacitance values ​​can be controlled within a specific range, and the actual variable capacitance range of the two is not the same in order to adapt the range coverage. Here, variable capacitor 200 is used to control the imaginary part of the impedance, and variable capacitor 201 controls the real part of the impedance.In this design scheme, only two variable capacitors are selected as components for the matching path control, primarily for the following reasons: Two variable capacitors are sufficient to meet the requirements of the matching path control, and adding more variable capacitors would only make the control algorithm more complex and the overall size of the matching mechanism larger. The inductor coil 210 and the grounding inductor 211 are the basic components of the impedance matching device 111, which together participate in the impedance matching process, and their inductance values ​​are both fixed. Finally, the fixed capacitor 202 used in this design scheme plays a compensatory role in the matching circuit, enabling it to adapt the impedance matching range to different matching requirements.At the same time, depending on the different matching requirements, it can also be placed in other positions in the matching circuit; in addition to the function of changing the matching range, the fixed capacitor 202 also serves the purpose of shunting and voltage division. As shown in Figs. 2-4, in each embodiment of the present application, the end of the variable capacitor 200 is electrically connected directly to the copper rod 220 of the RF input module 22. The head of the variable capacitor 201 is directly connected to the housing 1 via a grounding inductor 211. As shown in Figs. 2 and 7, in each embodiment of the present application, the variable capacitor 200 and the variable capacitor 201 are screwed to the partition 11 via an insulating connector 260 and an insulated connector 261, respectively. The use of insulating connectors prevents the high voltage at the capacitor from affecting the drive compartment 3 and the low-voltage compartment 4 through the partition 11, and the arrangement of the partition 11 effectively avoids unnecessary electromagnetic leakage so as not to impair the operation of the drive compartment 3 and the low-voltage compartment 4. By the above procedure, the adjustment of the bias bar 25 provides the DC voltage detection function of the output terminal for this matcher. The end of the bias bar 25 is mounted directly on the shield 141, which is mounted on the side wall of housing 1, and the head's detection cable is attached to the conductive connection 241 by means of a screw connection. As shown in Fig. 4-6, in each embodiment of the present application, the drive chamber 3 is arranged in a position close to the RF chamber 2 and separated from the RF chamber 2 by a partition 11 made of aluminum alloy, like the housing 1. The electromagnetic radiation from the RF chamber 2 can be prevented from interfering with the normal operation of the drive chamber 3 and the low-voltage chamber 4, since electromagnetic waves are effectively blocked by metal. The drive chamber 3 consists of a motor 300 connected to a variable capacitor 200, a motor 301 connected to a variable capacitor 201, a motor 300 with the central axis of a variable capacitor 200, and a motor 301 with the central axis of a variable capacitor 201. The actual capacitance values ​​of the variable capacitor 200 and the variable capacitor 201 are determined by the rotation of the motor 300 and the variable capacitor 201, respectively.The engine 301 was modified to achieve coverage of the appropriate area. As shown in Fig. 6, in each embodiment of the present application, the transmission connection is realized by means of a needle-like plug 32 and an insulating coupling 31, which is attached to the head of the motor and the capacitor. The use of insulated couplings 31 prevents the transmission of high voltage at the capacitor to the motor and the low-voltage compartment, which can effectively prevent motor failure and unnecessary electromagnetic leakage. As shown in Fig. 7, the low-voltage compartment 4 is adjacent to both the RF compartment 2 and the drive compartment 3, and the low-voltage compartment 4 is separated from the RF compartment 2 and the drive compartment 3, respectively, by the stepped partition 12 and the low-voltage partition 13. Similarly, as mentioned above, the stepped partition 12 and the low-voltage partition 13 are both made of aluminum alloy, which effectively blocks electromagnetic interference from the RF compartment 2 during the normal operation of the drive compartment 3 and the low-voltage compartment 4. As shown in Figs. 7-8, in each embodiment of the present application, the low-voltage compartment 4 is equipped with three circuit boards for matching control and communication. The signal line of the RF input module 22, the control line of the first motor 301, and the control line of the internal fan are all connected to the circuit board via the upper opening 120 of the stepped partition 12. The control cable of the external fan first enters the drive compartment 3 through opening 100 in the housing 1 and then connects to the circuit board via the upper opening 120 of the stepped partition 12. The RF output module 23 and the bias strip 25 are located throughout the RF compartment 2. To avoid electromagnetic interference, the signal line of the RF output module 23 is located entirely within the shield 140, and the signal line must flow through the cable duct 15 into the low-voltage compartment 4 and connect to the circuit board.Likewise, the signal line of the pre-tensioning strip 25 is placed completely in the shield 141, and the signal line must go through the shield 140 and the cable duct 15 into the low-voltage room 4 and connect to the circuit board. According to the above description, the various components of the entire impedance matching device 111 are placed in different and independent rooms to avoid electromagnetic interference between the components and to further improve the operational stability of the impedance matching device equipment. As shown in Figs. 1, 9, and 10, in one embodiment of the present application, the technical solution consists of an RF fan 500, which is arranged externally on the housing 1 at one end of the central axis of the corresponding inductor coil 210, and an RF heat dissipation opening 510 is provided at the other end, opposite the housing 1 and the RF fan 500. With the above-mentioned configuration, the airflow can be directed through the inductor coil 210 by means of air cooling, and the heat dissipation of the inductor coil 210 can be efficiently achieved. The upper surface of the RF partition 11 is equipped with an internal heat dissipation opening 512 at the upper position of the motor, which serves to direct the airflow from the RF chamber 2 into the drive chamber 3 in order to enhance the heat dissipation effect of the motor.The technical scheme consists of a low-voltage fan 501, a low-voltage fan 501 which is arranged on a low-voltage partition 13 and is located in the drive compartment 3, through which the airflow from the drive compartment 3 can be directed into the low-voltage compartment 4, and the lower plate 101 of the housing 1 corresponds to the position of the low-voltage fan 4 away from the low-voltage fan 501 with an additional heat dissipation opening 511, which is provided for exporting the airflow in the low-voltage compartment 4 in order to realize the heat dissipation of the low-voltage compartment 4.The cover plate 100 of the housing 1 corresponds to the position of the motor 300, and the motor 301 is equipped with motor heat dissipation holes which serve to connect the outer space of the housing 1 and the drive space 3 in order to dissipate heat for motor 300 and motor 301 on the one hand, and to direct the airflow over the low voltage space 4 through the low voltage fan 501 to dissipate heat on the circuit board. As shown in Figures 11-12, in each embodiment of the present application, the variable capacitor 200 and / or the variable capacitor 201 and / or the inductor coil 210 and / or RF chamber 2 are used to dissipate heat by liquid cooling, in particular water cooling. The coolant inlet 22 and outlet 23 are arranged side by side on the side wall of the housing 1. After the coolant enters RF chamber 2, it flows through the copper distributor 67 of the RF output module 23, which replaces the copper block 230 and the conductive connector 241 of the RF output module 23, and through the insulated liquid tube 68. The inductor coil is hollow, allowing the coolant to flow through the interior of the inductor coil 210 and through the copper liquid distribution channel at the ends of the first and second inductors, thereby replacing the conductive connector 240.The coolant then flows out of RF compartment 2 through the insulated liquid pipe and the output interface. The liquid cooling primarily cools the critical components of RF compartment 2, such as inductors and capacitors, and its cooling efficiency is higher than that of air cooling. As shown in Fig. 10, in each embodiment of the present application, the impedance matching device 111 is equipped with three interlock switches 40, each located on top of the stepped partition 12 in the drive area 3, at the bottom edge of the housing 1, and in the upper part of the input port of the RF input module 22 outside the housing 1. The impedance matching device 111 can only be switched on when the cover plate 100 and the bottom plate 101 of the housing 1 are installed and the RF cable is properly connected to the input terminal. This layer of mechanical safeguards effectively prevents the risk of electromagnetic leakage and the risk of ignition due to the absence of the interface during actual use of the detonator. The present application further discloses a power module with a matching component, which is named in one of the embodiments mentioned above, and the connection method from the input to the output of the power module is as follows: The output terminal of the power module is connected via an RF cable to the input terminal of the RF input module 22 of the impedance matching device 111, and the end of the variable capacitor 201 is grounded via the grounding inductor 211. The end of the variable capacitor 200 and the variable capacitor 201 are connected to one end of the inductor coil 210 via a conductive terminal 240, and the other end of the inductor coil 210 is connected via a copper block 230 of the conductive connector 241 and the RF output module 23 to the output terminal of the RF output module 23, between which a fixed capacitor 202 is grounded. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature CN 217470562U

[0004]

Claims

Impedance matching device (111) comprising a housing (1) in which a separation is provided within the housing (1) to divide the housing (1) into the following parts: - RF compartment (2) comprising RF circuit components; - drive compartment (3) comprising drive components; - low voltage compartment (4) comprising low voltage components, such as control components. Impedance matching device (111) according to claim 1, wherein the following RF circuit components are arranged in the RF space (2) as follows: - a first variable capacitor (200), a second variable capacitor (201) and a fixed capacitor (202), wherein the central axis of one or both of the variable capacitors (200, 201) is parallel to the central axis of the fixed capacitor (202). Impedance matching device (111) according to one of the preceding claims, wherein the following RF circuit component is arranged in the RF space (2) as follows: - an inductor coil (210), wherein the inductor coil (210) is arranged in a spiral. Impedance matching device (111) according to claim 3, wherein the central axis of the inductor coil (210) is perpendicular to the central axis of the fixed capacitor (202). Impedance matching device (111) according to one of the preceding claims 3 - 4, wherein the end of the variable capacitors (200, 201) is electrically connected to an end of the inductor coil (210). Impedance matching device (111) according to one of the preceding claims, wherein a fixed capacitor (202), a grounding inductor (211), an RF input module (22) and an RF output module (23) are arranged in the housing. Impedance matching device (111) according to one of the preceding claims, wherein one end of one, in particular both, variable capacitors (200, 201) is electrically connected to one end of the fixed capacitor (202) and subsequently electrically connected to the RF output module. Impedance matching device (111) according to one of the preceding claims, wherein one end of the first variable capacitor (200) is electrically connected to the RF input module (22). Impedance matching device (111) according to one of the preceding claims, wherein one end of the second variable capacitor (201) is electrically connected to the grounding inductor (211). Impedance matching device (111) according to one of the preceding claims, wherein one end of the grounding inductor (211) is electrically connected to the housing (1). Impedance matching device (111) according to one of the preceding claims, in which one, in particular both variable capacitors (200, 201) are each connected to a partition (11) by an insulating connector (260, 261), in particular screwed in place. Impedance matching device (111) according to one of the preceding claims, wherein an RF shield (141) is attached at the position of the RF output module (23), which corresponds to the housing, and the signal line of the RF output module (23) is arranged at least partially in the RF shield (141). Impedance matching device (111) according to one of the preceding claims, wherein the drive chamber (3) comprises: - a first motor (300) connected to the first variable capacitor (200) via a one-to-one gearbox, - a transmission shaft linearly connecting the first motor (300) to the first variable capacitor (200). Impedance matching device (111) according to one of the preceding claims, wherein the drive room (3) comprises: - a second motor (301) connected to the second variable capacitor (201) via a one-to-one gearbox, - a transmission link (30) linearly connecting the second motor (301) to the second variable capacitor (200). Impedance matching device (111) according to one of the preceding claims, wherein the transmission connection (30) is realized by a needle-like plug (32) between motor (300, 301) and variable capacitor (200, 201) and a coupling (31), in particular an electrically insulating one. Impedance matching device (111) according to one of the preceding claims, wherein an RF fan (500) is attached at the position of one end of the inductor coil (210) corresponding to the housing, and an RF heat dissipation opening (511) is attached on the opposite side of the RF fan (500) corresponding to the housing (1). Impedance matching device (111) according to one of the preceding claims, wherein the low-voltage compartment (4) adjoins both the drive compartment (3) and the RF compartment (2) and a partition (13) is provided at the position between the low-voltage compartment (4) and the drive compartment (3), which has an opening for the circuit connection between the two compartments. Impedance matching device (111) according to one of the preceding claims, wherein the RF partition (11) is equipped with an internal heat dissipation opening (512) at the position corresponding to the top of a motor (300, 301). Impedance matching device (111) according to one of the preceding claims, wherein a low-voltage fan (501) is mounted at the position between the low-voltage partition (13) of the passenger compartment and the low-voltage compartment, and the low-voltage fan (501) is arranged in the drive compartment (3) to direct the airflow between the low-voltage compartment (4) and the drive compartment (3). Impedance matching device (111) according to one of the preceding claims, wherein the housing (1) is equipped at the position of one end of the motor, corresponding to the motor, with a housing heat dissipation opening (511). Impedance matching device (111) according to one of the preceding claims, wherein the housing (1) is equipped with a cooling inlet and a cooling outlet opening and a cooling fluid tube (62) made of insulating material is installed in the RF space (2). Impedance matching device (111) according to one of the preceding claims, wherein a coolant distribution channel (68) is located at the position of the RF output module (23), and the inductor coil (210) is designed in the form of a hollow conduit, so that a coolant can flow through the coolant distribution channel (68) and from the inside through the inductor coil (210). Impedance matching device (111) according to one of the preceding claims, comprising a preload rod (25), wherein the end of the preload rod (25) is attached to the housing (1) and wherein the housing (1) is provided with a preload shield (141) at the position corresponding to the end of the preload rod (25). Impedance matching device (111) according to one of the preceding claims, wherein the partitions (11, 12, 13) and the housing (1) are made of metal materials. RF power module comprising an RF power supply, an RF cable and an impedance matching device (111) according to one of the preceding claims, wherein RF power supply comprises an output terminal and the output terminal is connected via the RF cable to the input terminal (22) of the impedance matching device (1).

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