Transformation system for connecting a plasma process control system to an impedance matching circuit, plasma-generating system having such a transformation system, and method for generating a transformation table and / or a transformation function

Abstract

A transformation system (10) is used for connecting a plasma process control system (2) to an impedance matching circuit A (9), wherein the impedance matching circuit A (9) is connectable to an RF generator (3) and a plasma chamber (5). A first transformation device (10a) and a communication device (14) are provided, wherein the communication device (14) is connectable to the plasma process control system (2). The communication device (14) is designed to receive control data B for an impedance matching circuit B (4) from the plasma process control system (2). The first transformation device (10a) is designed to transform the control data B for the impedance matching circuit B (4) into control data A for the impedance matching circuit A (9). The transformation system (10) is designed to provide the control data A for the control of the impedance matching circuit A (9). Additionally or alternatively, information data A may also be received from the impedance matching circuit A (9) and transformed into information data B for an impedance matching circuit B (4) and transmitted to the plasma process control system (2).

Description

[0001] Transformation system for connecting a plasma process control system to an impedance matching circuit, plasma generation system with such a transformation system and a method for generating a transformation table and / or a transformation function

[0002] The invention relates to a transformation system for connecting a plasma process control system to an impedance matching circuit, a plasma generation system with such a transformation system and a method for generating a transformation table and / or a transformation function.

[0003] The surface treatment of workpieces using plasma and gas lasers is an industrial process in which a plasma is generated, particularly in a plasma chamber, using direct current or a high-frequency alternating signal with an operating frequency in the range of a few 10 kHz up to the GHz range.

[0004] The plasma chamber is connected to a high-frequency generator (HF generator) via additional electronic components such as coils, capacitors, cables, or transformers. These additional components can represent resonant circuits, filters, or impedance matching circuits.

[0005] Plasma processes represent a highly variable load for a high-frequency generator, depending on the conditions in the plasma chamber. In particular, the properties of the workpiece, electrodes, and gas conditions are important.

[0006] High-frequency generators have a limited operating range depending on the impedance of the connected electrical load. If the load impedance exceeds a permissible range, the required energy / power cannot be delivered to the load. Damage to the RF generator is also possible.

[0007] For this reason, an impedance matching circuit, also called a “match box”, is often used to transform the impedance of the load to a nominal impedance of the generator output.

[0008] Various impedance matching circuits are known. For example, the impedance matching circuits can be fixed and have a predetermined transformation effect, thus consisting, for example, of electrical components, in particular coils and capacitors, which are not changed during operation. This is particularly useful for constant operation, such as in a gas laser. Furthermore, impedance matching circuits are known in which at least some of the components of the impedance matching circuit are mechanically variable. For example, motor-driven variable capacitors are known, whose capacitance value can be changed by changing the arrangement of the capacitor plates relative to one another. Furthermore, impedance matching circuits are known in which at least some of the components of the impedance matching circuit are electrically or magnetically variable. For example,Reactances can be switched on using semiconductor components or their properties can be changed by applying electric and / or magnetic fields.

[0009] Roughly speaking, a plasma can be assigned three impedance ranges. Before ignition, very high impedances exist. During normal operation, i.e., when plasma is used as intended, lower impedances exist. Very low impedances can occur during unwanted local discharges, also called 'arcs,' or during plasma fluctuations. In addition to these three identified impedance ranges, other special states with different associated impedance values ​​can occur. If the load impedance changes suddenly and the load impedance or the transformed load impedance moves outside of a permissible impedance range, the RF generator or transmission equipment between the RF generator and the plasma chamber can be damaged. Furthermore, there are also stable plasma states that are undesirable.

[0010] An impedance matching circuit is described, for example, in DE 10 2009 001 355 A1. Plasma processes carried out using such a plasma generation system, which includes at least the RF generator and the impedance matching circuit, must always proceed in exactly the same way to achieve the same result. This is all the more true since the plasma process is integrated into a semiconductor process. Semiconductor processes include many additional steps, each of which must proceed within a precisely predefined framework. Every process parameter must always be exactly the same; otherwise, for example, a wafer cannot be produced reproducibly.

[0011] One problem is replacing one component of the plasma generation system with another. Reasons for such a replacement can be seen in the improved properties of the new component, such as lower energy consumption. For example, impedance matching circuit B can be replaced by a new impedance matching circuit A that, for example, is more efficient, can operate over a wider frequency range, or can be adjusted more precisely or quickly.

[0012] It is therefore the object of the present invention to create a way to continue achieving a stable and reproducible plasma process, even if one component of the plasma generation system is replaced by another component. This object is achieved by a transformation system for connecting a plasma process control system to an impedance matching circuit according to independent claim 1. Claims 2 to 13 describe further developments of the transformation system. Claim 14 describes a corresponding plasma generation system with such a transformation system, whereas claim 15 describes a further development of the plasma generation system. Claim 16 describes a method for generating a transformation table and / or a transformation function that can utilize the transformation system.

[0013] The transformation system according to the invention serves to connect a plasma process control system to an impedance matching circuit A. The impedance matching circuit A can be connected between an RF generator and a plasma chamber. The impedance matching circuit A is the impedance matching circuit that is to be controlled during operation. It can therefore also be called the "in-operation impedance matching circuit." The transformation system comprises a first transformation device and a communication device, wherein the communication device is connectable to the plasma process control system. The communication device is designed to receive control data B for an impedance matching circuit B, in particular from the plasma process control system. The communication device can therefore also be called a data communication device.Impedance matching circuit B is the impedance matching circuit that is no longer in operation, i.e., is to be replaced by impedance matching circuit A, or has been replaced. Impedance matching circuit B can therefore also be called the 'non-operational impedance matching circuit', and control data B can be called the 'non-operational control data'. However, the plasma process was already successfully operated at an earlier time using impedance matching circuit B. A first transformation device is designed to transform control data B for impedance matching circuit B into control data A for impedance matching circuit A. The first transformation device can therefore also be called the first data transformation device, and control data A can also be called 'operational control data'.

[0014] The transformation system is further designed to provide the control data A for controlling the impedance matching circuit A. In addition or as an alternative to the transformation of the control data B into control data A, the transformation system, in particular the first transformation device, is designed to receive information data A from the impedance matching circuit A. The first transformation device is then designed to transform the received information data A from the impedance matching circuit A into information data B of the impedance matching circuit B. The information data A can also be called 'in-operation information data' and the information data B can also be called 'non-in-operation information data'. The communication device is designed to provide the information data B, in particular to transmit it to the plasma process control system.It is particularly advantageous that the transformation also takes place in this reverse direction, i.e., that information data A originating from the impedance matching circuit A is transformed into information data B that looks as if it originated from the impedance matching circuit B. This ensures proper operation of the plasma process control system, which, for example, displays this transformed information data B to a user or further calculates it and, if necessary, uses it for control purposes.

[0015] Impedance matching circuit A and impedance matching circuit B have different properties. These different properties can include, for example, efficiency, power dissipation, frequency dependence, component sizes, switching components, motors, and / or other components used. At the same time, impedance matching circuit A is designed to be a suitable replacement for impedance matching circuit B. This can mean that it is designed for comparable or higher power, a comparable or wider frequency range, and a comparable or wider input and output impedance range. It can at least do everything that impedance matching circuit B required in the plasma process, and possibly even more.

[0016] It is particularly advantageous to use a transformation system that can be arranged between the impedance matching circuit A and, for example, a higher-level plasma process control system. This allows control commands, such as control data generated by the plasma process control system, to be transformed or modified and only forwarded to the impedance matching circuit A after such a transformation. The entire plasma process can thus be designed for use with the impedance matching circuit B. If the impedance matching circuit B is replaced by a newer impedance matching circuit A, control data B used to control the impedance matching circuit B cannot simply be used to control the impedance matching circuit A. If this control data B were simply used without transformation, the plasma process would suddenly produce different results.

[0017] As mentioned above, one or both of the impedance matching circuits A / B can comprise at least one mechanically, in particular motor-driven, adjustable reactance, in particular in the form of at least one mechanically, in particular motor-driven, adjustable capacitance, in order to change the transformation ratio during operation of the impedance matching circuit. This allows different impedances to be provided at the output terminal of the impedance matching circuit in order to transfer as much power as possible into the plasma via the plasma chamber. Furthermore, a defined impedance can also be achieved at the input terminal of the impedance matching circuit in order to reduce or prevent reflections back to the RF generator.The respective control data are preferably data from which the position of the at least one mechanically, in particular motor-driven, adjustable reactance can be determined directly or indirectly. The position of the at least one mechanically, in particular motor-driven, adjustable reactance can be different for two different impedance matching circuits in order to nevertheless be able to achieve the same impedance at the output terminal or at the input terminal of the impedance matching circuit.

[0018] The transformation system according to the invention not only allows the use of a new impedance matching circuit A, but also eliminates the need to make any changes to the plasma process supply system. This eliminates the need to make corresponding changes to the complex plasma process supply system, which may include controls for hundreds of process steps.

[0019] In an advantageous further development, the transformation system can be used directly in a data connection between the plasma process supply system and the impedance matching circuit A. The transformation system preferably acts as a so-called black box for the operator of the plasma process control system.

[0020] In an advantageous development, the transformation system is designed to transmit the control data A to the impedance matching circuit A and thereby control the impedance matching circuit A. The impedance matching circuit A is then designed to make settings according to the control data A or to execute the control data A.

[0021] In an advantageous development, the first transformation device comprises a transformation table and / or a transformation function in order to transform the control data B for the impedance matching circuit B into control data A for the impedance matching circuit A. A corresponding transformation table can, for example, comprise a direct translation between position information for the impedance matching circuit B to position information for the impedance matching circuit A. If the impedance matching circuits A and B each comprise, for example, exactly one mechanically, in particular motor-driven, adjustable reactance, the transformation table can receive the information that a position of, for example, 5 mm or 20° for the impedance matching circuit B corresponds to a position of, for example, 12 mm or 53° for the impedance matching circuit A.If control data is now transmitted from the plasma process control system to the transformation device, which includes the corresponding position of, for example, 5 mm or 20° for the impedance matching circuit B, the translation device is designed to replace this position with the new position of, for example, 12 mm or 53° and transmit it to the impedance matching circuit A. The new position causes the impedance matching circuit A to be set to the same impedance as the old position for the impedance matching circuit B. The plasma process is therefore carried out with the physically identical parameters despite the new impedance matching circuit A.

[0022] The transformation table is therefore preferably a look-up table. If the impedance matching circuit A comprises a plurality of adjustable reactances, in particular in the form of capacitances, there are correspondingly a plurality of new positions. Of course, the impedance matching circuit B can also comprise a plurality of adjustable reactances, in particular in the form of capacitances, in which case there are correspondingly a plurality of positions. Preferably, for one position for a first adjustable reactance, there are a plurality of positions for a second adjustable reactance. This is the case for both the impedance matching circuit B and the impedance matching circuit A.For each pair of position for the first adjustable reactance and position for the second adjustable reactance of the impedance matching circuit B, there is a pair of position for the first adjustable reactance and position for the second adjustable reactance of the impedance matching circuit A.

[0023] By using a corresponding transformation function, the memory requirement can be reduced. The transformation system is designed to insert the received control data B for the impedance matching circuit B into the transformation function and to obtain transformed control data A for the impedance matching circuit A based on the result of the transformation function.

[0024] In an advantageous further development, the control data B for the impedance matching circuit B comprise manipulated variables for at least one mechanically, in particular motor-driven, adjustable reactance in the impedance matching circuit B. Furthermore, the control data A for the impedance matching circuit A comprise manipulated variables for at least one mechanically, in particular motor-driven, adjustable reactance for the impedance matching circuit A.

[0025] In an advantageous development, the control data for the impedance matching circuit B comprise position information and / or capacitance information for at least one mechanically, in particular motor-adjustable, reactance arranged in the impedance matching circuit B in order to provide a specific impedance target value at the output terminal of the impedance matching circuit B. The first transformation device is designed to transform the control data for the impedance matching circuit B into control data for the impedance matching circuit A, wherein the control data for the impedance matching circuit A comprise position information for at least one mechanically, in particular motor-adjustable, reactance arranged in the impedance matching circuit A.This transformed position information makes it possible to provide the same impedance target value at the output terminal of the impedance matching circuit A as at the output terminal of the impedance matching circuit B.

[0026] In an advantageous development, the information data A comprises current position information for at least one mechanically, in particular motor-driven, adjustable reactance in the impedance matching circuit A and / or current capacitance information for at least one mechanically, in particular motor-driven, adjustable reactance in the impedance matching circuit A and / or a currently set transformation ratio in the impedance matching circuit A and / or a current efficiency of the impedance matching circuit A and / or at least one current value for a voltage and / or current at or in the impedance matching circuit A.

[0027] In an advantageous development, the first transformation device comprises a transformation table and / or a transformation function for transforming the information data A for the impedance matching circuit A into information data B for the impedance matching circuit B. This transformation table and / or a transformation function can be constructed in a similar manner, but preferably inversely, to the transformation table and / or a transformation function for transforming the control data.

[0028] In an advantageous development, the communication device is designed to receive a target generator power B for the RF generator for use of the impedance matching circuit B from the plasma process control system. A second transformation device is designed to transform the target generator power B for use of the impedance matching circuit B into a target generator power A for use of the impedance matching circuit A. The second transformation device is further designed to transmit the transformed or modified target generator power A to the RF generator. This ensures that the RF generator outputs the RF signal with a modified power, so that the same power is again present in the plasma. The power should be modified if the impedance matching circuit A has an efficiency that is different from the efficiency of the impedance matching circuit B.The efficiency should preferably be related to the correspondingly set impedance at the output terminal of the impedance matching circuit. If the efficiency of impedance matching circuit A differs from the efficiency of impedance matching circuit B when the position of the at least one mechanically, in particular motor-controlled, adjustable reactance is set via the transformed manipulated variable, then transforming the target generator power can ensure that the same power is delivered into the plasma when using impedance matching circuit A as when using the older impedance matching circuit B. No changes to the plasma process control system are required.

[0029] In an advantageous further development, the second transformation device is designed to transform the target generator power B received from the plasma process control system as a function of a variable, wherein the variable can describe an efficiency difference between the impedance matching circuit A and the impedance matching circuit B.

[0030] In an advantageous development, the second transformation device is designed to transform the target generator power B received from the plasma process control system as a function of an efficiency difference between an efficiency of the impedance matching circuit A and an efficiency of the impedance matching circuit B, wherein the efficiency of the impedance matching circuit A results when operated with the transformed manipulated variable A and wherein the efficiency of the impedance matching circuit B results when operated with the manipulated variable B. If the impedance matching circuit A is, for example, 20% more efficient than the impedance matching circuit B, the target generator power of the RF generator should be reduced accordingly to ensure that the same power arrives in the plasma.

[0031] In an advantageous development, the second transformation device is designed to reduce the target generator power received by the plasma process control system if the efficiency of the impedance matching circuit A is greater than the efficiency of the impedance matching circuit B. Additionally or alternatively, the second transformation device is designed to increase the target generator power received by the plasma process control system if the efficiency of the impedance matching circuit A is less than the efficiency of the impedance matching circuit B.

[0032] In an advantageous development, the second transformation device is designed to receive an actual generator power from the RF generator with connected impedance matching circuit A. In a first alternative, the second transformation device is designed to increase the actual generator power if the efficiency of impedance matching circuit A is greater than the efficiency of impedance matching circuit B. The communication device is then designed to transmit the increased actual generator power to the plasma process control system. In addition or alternatively, in a second alternative, the second transformation device is designed to reduce the actual generator power if the efficiency of impedance matching circuit A is less than the efficiency of impedance matching circuit B.The communication device is then designed to transmit the reduced actual generator power to the plasma process control system.

[0033] In an advantageous development, the communication device is configured to receive a frequency setpoint for the RF generator from the plasma process control system. The second transformation device is configured to transmit the frequency setpoint to the RF generator without changing the frequency. In addition or as an alternative to transmitting a frequency setpoint for the RF generator, it is also possible for a start / stop signal or an information signal indicating whether the RF generator should generate a CW signal or a pulse signal to be transmitted untransformed to the RF generator.

[0034] The plasma generation system according to the invention comprises a transformation system, as already described. The plasma generation system also comprises an RF generator, an impedance matching circuit A, and a plasma process control system, in particular a higher-level one. Optionally, a consumer, in particular in the form of a plasma chamber, is also provided. The plasma process control system is connected to the transformation system, preferably via a cable connection. This cable connection is, for example, an optical and / or galvanic connection. The RF generator is connected to the impedance matching circuit A.

[0035] In an advantageous further development, impedance matching circuit A is the impedance matching circuit currently used in the plasma generation system, and impedance matching circuit B is the impedance matching circuit previously used in the plasma generation system, i.e., in the past. Corresponding plasma processes that can be provided by the plasma chamber were tested with the older impedance matching circuit B and are now also intended to be used with the newer impedance matching circuit A.

[0036] In an advantageous development of the plasma generation system, the transformation system is designed as a separate system between the RF generator, the impedance matching circuit A, and the plasma process control system. Alternatively, the transformation system is designed as a module in the RF generator and / or as a module in the impedance matching circuit A. Alternatively, the transformation system is designed as a module in the plasma process control system. A module can be a hardware module and / or a software module.

[0037] The method according to the invention serves to generate a transformation table and / or a transformation function in order to transform control data for the impedance matching circuit B into control data for the impedance matching circuit A. In a first method step, a vector network analyzer (VNA) is connected to the input terminal and the output terminal of the impedance matching circuit B. In a second method step, an impedance at the output terminal for a position for at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B is determined. In a third method step, the position of the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B is changed and then the second method step is repeated.In a fourth method step, a vector network analyzer is connected to the input terminal and the output terminal of the impedance matching circuit A. In a fifth method step, an impedance at the output terminal for a position for at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit A is determined. In a sixth method step, the position of the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit A is changed, and the fifth method step is then repeated. It is clear that method steps 1 to 3 and 4 to 6 can also be performed interchangeably. In this case, method steps 4 to 6 would be performed before method steps 1 to 3. If the vector network analyzer has four ports, the impedance matching circuit A and the impedance matching circuit B can also be measured simultaneously.In a seventh method step, a transformation table and / or a transformation function is created by means of which a position of the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B can be converted into a position for the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit A, wherein the impedance at the output terminal of the impedance matching circuit A is equal to the impedance at the output terminal of the impedance matching circuit B or deviates by less than a threshold value.

[0038] A further method according to the invention describes the operation of the transformation system described above. The plasma process control system is connected to the impedance matching circuit A via the transformation system. In a first method step, a communication device of the transformation system receives control data B for an impedance matching circuit B from the plasma process control system. In a second method step, the first transformation device transforms the control data B for the impedance matching circuit B into control data A for the impedance matching circuit A. In a third method step, the transformation system makes the transformed control data A available to the impedance matching circuit A. In addition to or as an alternative to method steps 1 to 3, the further method steps can also be carried out.In a fourth method step, the transformation system receives information data A from the impedance matching circuit A. In a fifth method step, the first transformation device transforms the received information data A from the impedance matching circuit A into information data B of the impedance matching circuit B. In a sixth method step, the communication device transmits the information data B to the plasma process control system.

[0039] Impedance matching circuit A may also be referred to as the first impedance matching circuit. Impedance matching circuit B may also be referred to as the second impedance matching circuit. Control data A may also be referred to as the first control data. Control data B may also be referred to as the second control data.

[0040] Information data A can also be referred to as first information data. Information data B can also be referred to as second information data.

[0041] The first and / or second transformation device is preferably a processor and / or FPGA and / or microcontroller and / or ASIC that is programmed and / or configured according to the suitability or configuration or described method steps and / or onto which a program can be loaded that enables it to perform the described method steps or to provide the suitability or configuration. A transformation device can also include, among other things, a memory device for this purpose.

[0042] The communication device is preferably a digital data interface. This can be wired or wireless. It can use one or more data communication protocols known to those skilled in the art.

[0043] The invention is described below purely by way of example with reference to the drawings. They show:

[0044] Figure 1 : an embodiment of a plasma generation system with a

[0045] Plasma process control system, an impedance matching circuit B, wherein the impedance matching circuit B is connected to an RF generator and a plasma chamber;

[0046] Figures 2 and 3: the plasma generation system from Figure 1, wherein the impedance matching circuit B is replaced by an impedance matching circuit A and wherein the plasma generation system comprises the transformation system according to the invention;

[0047] Figures 4A, 4B: various embodiments of how an impedance matching circuit can be constructed;

[0048] Figure 5: an embodiment explaining how a transformation table and / or a transformation function can be generated for the transformation system;

[0049] Figures 6A, 6B: differently adjustable impedances at the output terminal of the impedance matching circuit B and the impedance matching circuit A;

[0050] Figures 7, 8: embodiments of how a measuring unit for measuring a current and a voltage can be designed, and

[0051] Figure 9: a flowchart for a method illustrating the operation of the

[0052] T ransformation system explained.

[0053] Figure 1 shows a plasma generation system 100 comprising a plasma process control system 2. The plasma generation system 100 further comprises an RF generator 3, an impedance matching circuit B4, and at least one load 5, in particular in the form of a plasma chamber. The RF generator 3 is designed to provide a high-frequency signal, in particular in the form of a pulsed high-frequency signal, with a nominal power PNom and a frequency fo and to output it at an output terminal 3a. The impedance matching circuit B4 comprises an input terminal 4a, wherein the RF generator 3 is connected with its output terminal 3a to the input terminal 4a via a first cable connection 6a. The impedance matching circuit B4 further comprises an output terminal 4b. The output terminal 4b is connected to the at least one load 5 via a second cable connection 6b.The first and / or second cable connection 6a, 6b may comprise one or more cables, for example, connected in series and / or in parallel. Coaxial cables are preferably used.

[0054] The consumer 5, i.e., the plasma chamber, comprises at least one electrode 7 for generating a plasma 8. The electrode 7 is connected to the output terminal 4b of the impedance matching circuit B 4. In this embodiment, a camera system 91 is also arranged in the plasma chamber, which is designed to observe the plasma 8.

[0055] The plasma process control system 2 is preferably a processor and / or FPGA and / or microcontroller and / or ASIC that is programmed and / or configured according to the suitability or configuration or described method steps and / or onto which a program can be loaded that enables it to perform the described method steps or provide the suitability or configuration. The plasma process control system 2 can also include, among other things, a memory device for this purpose.

[0056] The plasma process control system 2 is designed to control the RF generator 3, in particular to activate or deactivate it. Additionally or alternatively, the plasma process control system 2 is also designed to change the power and / or frequency of the RF signal by appropriately controlling the RF generator 3. Additionally or alternatively, the plasma process control system 2 is designed to change the waveform of the high-frequency signal by appropriately controlling the RF generator 3. This can, for example, relate to: the type of high-frequency signal, modulation of the RF signal, pulse durations, pulse repetition rate.

[0057] The plasma process control system 2 is preferably also configured to control the impedance matching circuit B4. In particular, the plasma process control system 2 is configured to change the transformation ratio within the impedance matching circuit B4 and / or to specify an impedance at the output terminal 4b. Additionally or alternatively, the plasma process control system 2 is configured to specify the impedance at the input terminal 4a acting on the RF generator 2. For this purpose, the plasma process control system 2 transmits control data B to the impedance matching circuit B4.

[0058] The plasma generation system 1 further comprises a measuring unit 11. The measuring unit 11 is preferably arranged between the RF generator 3 and the impedance matching circuit B4. The measuring unit 11 is designed, for example, to measure a power transmitted from the RF generator 3 toward the impedance matching circuit B4 and to measure a power reflected back toward the RF generator 3. In principle, the measuring unit 11 can also be designed to measure an impedance value at the input terminal 4a of the impedance matching circuit 4.

[0059] For this purpose, the measuring unit 11 comprises, for example, a directional coupler unit. Using the directional coupler unit, the measuring unit 11 can measure the power of a forward and return high-frequency signal on the first cable connection 6a in order to calculate the respective power or impedance at the input terminal 4a from this. The measuring unit 11 can alternatively also comprise a current sensor 16 and a voltage sensor 20. A configuration with a current sensor 16 and a voltage sensor 20 is shown in Figures 7 and 8. The control device 1 is designed to calculate the respective power or impedance at the input terminal 4a, which the RF generator 3 sees, based on the measurement result of the directional coupler unit or the current sensor 16 and the voltage sensor 20.

[0060] The plasma generation system 1 preferably also includes an operating unit 12. The operating unit 12 is preferably a screen, in particular a touch-sensitive screen. In addition to a screen, the operating unit 12 can also include input devices such as a keyboard and / or mouse. The operating unit 12 can also be a web server that provides data and receives user input. The plasma process control system 2 is designed to display current settings of the RF generator 3 and / or the impedance matching circuit B4 on the operating unit 12.

[0061] The plasma process control system 2 is preferably configured to receive setpoint specifications, for example for the power of the high-frequency signal, from the control unit 12. Furthermore, the frequency of the high-frequency signal and / or the waveform of the high-frequency signal and / or the pulse rate and / or the pulse duration for the high-frequency signal can be received by the control unit 12. A desired impedance at the output terminal 4b of the impedance matching circuit B4 can also be received via the control unit 12. From this, corresponding manipulated variables for the RF generator 3 and control data B for the impedance matching circuit B4 can be generated and transmitted to it.

[0062] Figures 2 and 3 show two variants of a plasma generation system 1 that has been modified compared to the plasma generation system 100 of Figure 1. In both variants, the impedance matching circuit B 4 is replaced by an impedance matching circuit A 9. The impedance matching circuit A 9 also includes an input terminal 9a and an output terminal 9b. The impedance matching circuit A 9 is also connected between the RF generator 3 and the load 5.

[0063] The structure of the impedance matching circuit A 9 differs from the structure of the impedance matching circuit B 4 at least in that, in the event that the same control data is transmitted to the impedance matching circuit A 9 as to the impedance matching circuit B 4, a different impedance is present at the output terminal 9b of the impedance matching circuit A 9.

[0064] One reason for replacing the impedance matching circuit B 4 with the impedance matching circuit A 9 can be, for example, that a larger impedance range is to be provided at the output terminal 9a of the impedance matching circuit A 9 or that the efficiency of the plasma generation system 1 is to be increased by using the impedance matching circuit A 9. It may also be the case that certain components of the impedance matching circuit B 4 are no longer available, so that an impedance matching circuit with modified electrical properties must inevitably be produced.

[0065] In order to be able to use such a new impedance matching circuit A 9 without adapting the plasma process control system 2, the invention proposes the use of a transformation system 10 according to the invention.

[0066] In Figure 2, the transformation system 10 according to the invention is arranged between the plasma process control system 2 and the impedance matching circuit A9, as well as between the plasma process control system 2 and the RF generator 3. The plasma process control system 2 subsequently communicates, in particular only, via the transformation system 10 with the impedance matching circuit A9 and / or the RF generator 3. Preferably, both the communication from the plasma process control system 2 to the impedance matching circuit A9 and / or to the RF generator 3 and the communication from the impedance matching circuit A9 and / or the RF generator 3 to the plasma process control system 2 are routed via the transformation system 10.

[0067] The transformation system 10 comprises a communication device 14, via which data transmission with the plasma process control system 2 is possible. The transformation system 10 further comprises a first transformation device 10a, which is configured to receive control data B for the impedance matching circuit B 4 from the plasma process control system 2 and to transform it into control data A for the impedance matching circuit A 9. The transformation system 10 is configured to control the impedance matching circuit A 9 with the transformed control data A. This control also includes transmitting this transformed control data A to the impedance matching circuit A 9.

[0068] The first transformation device 10a preferably comprises a transformation table and / or a transformation function in order to transform the control data B, which are intended for controlling the impedance matching circuit B 4, into control data A for the impedance matching circuit A 9.

[0069] The impedance matching circuit B 4 is not physically present in either the embodiment of Fig. 2 or the embodiment of Fig. 3. However, for the plasma process control system 2, it appears as if it were present. Therefore, in both Figures 2 and 3, the impedance matching circuit B 4 is shown in dashed lines in the background. The control data B for the impedance matching circuit B 4 includes manipulated variables for at least one mechanically, in particular motor-driven, adjustable reactance in the impedance matching circuit B 4. The control data A for the impedance matching circuit A 9 includes manipulated variables for at least one mechanically, in particular motor-driven, adjustable reactance 52, 53, as shown in Figures 4A, 4B, for the impedance matching circuit A 9.

[0070] The transformation system 10 is preferably configured to receive information data A from the impedance matching circuit A 9 . The first transformation device 10a is configured to transform the received information data A from the impedance matching circuit A 9 into information data B from the impedance matching circuit B 4 . The communication device 14 is configured to transmit the transformed information data B to the plasma process control system 2 . As a result, the plasma process control system 2 has information data B that is plausible with the information data that the impedance matching circuit B 4 would have output. This is particularly advantageous when the information data B is displayed on the operating unit 12.

[0071] The information data A is, in particular, current position information for at least one mechanically, in particular motor-driven, adjustable reactance 52, 53 in the impedance matching circuit A 9 and / or current capacitance information for at least one mechanically, in particular motor-driven, adjustable reactance 52, 53 in the impedance matching circuit A 9 and / or a currently set transformation ratio in the impedance matching circuit A 9 and / or a current efficiency of the impedance matching circuit A 9 and / or at least one current value for a voltage and / or current at or in the impedance matching circuit A 9. The first transformation device 10a preferably comprises a transformation table and / or a transformation function in order to transform the information data A for the impedance matching circuit A 9 into information data B for the impedance matching circuit B 4.

[0072] The communication device 14 of the transformation system 10 is preferably also configured to receive a target generator power for the RF generator 3 for use with the impedance matching circuit B4 from the plasma process control system 2. The transformation system 10 comprises a second transformation device 10b. The second transformation device 10b is configured to transform the target generator power for use with the impedance matching circuit B4 into a target generator power for use with the impedance matching circuit A9. The second transformation device 10b is configured to transmit the modified target generator power to the RF generator 3.

[0073] The second transformation device 10b is designed to reduce the target generator power received by the plasma process control system 2 if the efficiency of the impedance matching circuit A9 is greater than the efficiency of the impedance matching circuit B4. Additionally or alternatively, the second transformation device 10b is designed to increase the target generator power received by the plasma process control system 2 if the efficiency of the impedance matching circuit A9 is less than the efficiency of the impedance matching circuit B4.

[0074] Preferably, the second transformation device 10b is designed to receive an actual generator power from the RF generator 3 with connected impedance matching circuit A 9 . The second transformation device 10b is designed to increase the actual generator power if the efficiency of the impedance matching circuit A 9 is greater than the efficiency of the impedance matching circuit B 4 . The communication device 14 is designed to transmit the increased actual generator power to the plasma process control system 2. Additionally or alternatively, the second transformation device 10b is designed to reduce the actual generator power if the efficiency of the impedance matching circuit A 9 is less than the efficiency of the impedance matching circuit B 4 . The communication device 14 is designed to transmit the reduced actual generator power to the plasma process control system 2.

[0075] The communication device 14 is configured to receive a frequency setpoint for the RF generator 3 from the plasma process control system 2. The second transformation device 10b is configured to transmit the frequency setpoint to the RF generator 3 without changing the frequency. Additionally or alternatively, the second transformation device 10b is configured to receive an actual frequency value from the RF generator 3 and to transmit the actual frequency value to the plasma process control system 2 without changing the frequency by means of the communication device 14.

[0076] In Figure 2, the transformation system 10 is designed as a separate system between the RF generator 3, the impedance matching circuit A 9 and the plasma process control system 2.

[0077] In contrast to Figure 2, the transformation system 10 in Figure 3 is formed both in the RF generator 3 and in the impedance matching circuit A9. In this case, the first transformation device 10a is arranged in the impedance matching circuit A9, and the second transformation device 10b is arranged in the RF generator 3. The corresponding communication device 14 of the transformation system 10 is arranged in both the impedance matching circuit A9 and the RF generator 3. The plasma process control system 2 then communicates directly with the first and second transformation devices 10a, 10b in the impedance matching circuit A9 and in the RF generator 3, respectively.

[0078] The following applies to both the embodiment shown in Fig. 2 and the embodiment shown in Fig. 3:

[0079] - The transformation system 10 can also be arranged or implemented at least partially on or in the plasma process control system 2 without restrictions.

[0080] - The transformation system 10 can also be arranged or implemented at least partially on or in the RF generator 3 without restrictions.

[0081] - The transformation system 10 can, without restrictions, also be arranged or implemented at least partially on or in the impedance matching circuit A 9, in particular in a controller of the impedance matching circuit A 9.

[0082] Figures 4A and 4B show a possible embodiment of the impedance matching circuit A 9. In principle, the impedance matching circuit B 4 can also be constructed in an analogous manner, wherein the positions for the mechanically, in particular motor-driven, adjustable reactances 52, 53 are different in order to achieve the same capacitance values.

[0083] If the impedance matching circuit A 9 contains several impedance transformation stages, each impedance transformation stage can be constructed according to the embodiment of Figures 4A, 4B. It is clear that the impedance matching circuit A 9 can also be constructed differently than shown in Figures 4A, 4B. In Figure 5A, the input terminal 9a of the impedance matching circuit A 9 is connected to a first coil 50 or first inductance and to a second coil 51 or second inductance. The first terminals of the first and second coils 50, 51 are connected to a common node and thus to the input terminal 9a of the impedance matching circuit A 9. The first coil 50 is connected to a reference ground via a first capacitor 52 or first capacitance. The second coil 51 is connected to the output terminal 9b via a second capacitor 53 or second capacitance.The first and / or second capacitors 52, 53 are adjustable components, in particular in the form of variable capacitors whose capacitance can be changed via stepper motors. In particular, the plate spacing of the first and second capacitors 52, 53 can be changed. The plasma process control system 2 is designed to control the respective stepper motors accordingly. The capacitances of the first and second capacitors 52, 53 can be adjusted independently of one another. Preferably, the impedance matching circuit A9 is free of further components. Of course, the position of the first coil 50 and the first capacitor 52 can also be swapped. In this case, the first capacitor 52 is arranged at the input terminal 9a of the impedance matching circuit A9, and the first coil 50 is arranged at the reference ground. Additionally or alternatively, the position of the second coil 51 and the second capacitor 53 can also be swapped.In this case, the second capacitor 53 is arranged at the input terminal 9a of the impedance matching circuit A 9 and the second coil 51 is arranged at the output terminal 9b of the impedance matching circuit A 9.

[0084] In Figure 4B, the input terminal 9a of the impedance matching circuit A9 is connected to the first capacitor 52 or first capacitance. The first capacitor 52 is connected to both the first coil 50 or first inductance and the second coil 51 or second inductance. This occurs via a common node to which both the first capacitor 52 and the first and second coils 50, 51 are connected. The first coil 50 is also connected to the reference ground. The second coil 51 is connected to the second capacitor 53 or second capacitance, in particular in series. The second capacitor 53 is connected to the output terminal 9b of the impedance matching circuit A9. The position of the second coil 51 and the second capacitor 53 could also be reversed.In this case, the second capacitor 53 would be connected to the common node and the second coil 51 would be connected to the output terminal 9b of the impedance matching circuit A9. Preferably, the impedance matching circuit A9 is free of any additional components.

[0085] Figure 5 shows an embodiment that explains how a transformation table and / or a transformation function for the transformation system 10 can be generated. A vector network analyzer 13 is connected to the input terminal 4a and the output terminal 4b of the impedance matching circuit B4. An impedance at the output terminal 4b is then determined for a position for at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B4. Subsequently, the position of the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B4 is changed. Subsequently, the impedance is again determined and the reactance is adjusted. The vector network analyzer 13 is then connected to the input terminal 9a and the output terminal 9b of the impedance matching circuit A9.The impedance at the output terminal 9b is determined for a position for at least one mechanically, in particular motor-driven, adjustable reactance 52, 53 of the impedance matching circuit A9. Subsequently, the position of the at least one mechanically, in particular motor-driven, adjustable reactance 52, 53 of the impedance matching circuit A9 is changed. Subsequently, the impedance and the adjustment of the reactance 52, 53 are determined again.Based on this information, a transformation table and / or a transformation function can be created by means of which a position of the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B 4 can be converted into a position for the at least one mechanically, in particular motor-driven, adjustable reactance 52, 53 of the impedance matching circuit A 9, wherein the impedance at the output terminal 9b of the impedance matching circuit A 9 is equal to the impedance at the output terminal 4b of the impedance matching circuit B 4 or deviates by less than a threshold value.

[0086] Figures 6A and 6B show differently adjustable impedances 15, 17 at the output terminal 4b, 9b of the impedance matching circuit B4 (Figure 6A) and the impedance matching circuit A9 (Figure 6B). The impedances 15, 17 can have complex values, i.e., with a real part R (ohms) and an imaginary part X (ohms). Therefore, the possible impedances 15, 17 are each represented as areas. It can be seen that the newer impedance matching circuit A9 can set a larger area of ​​impedances 17 at its output terminal 9b than the older impedance matching circuit B4. For each of the possible adjustable impedance values, there is a position for at least one mechanically, in particular motor-driven, adjustable reactance 52, 53.In particular, motor positions for setting a first impedance at the output terminal 4b of the impedance matching circuit B 4 are different from motor positions for setting the same first impedance at the output terminal 9b of the impedance matching circuit A 9.

[0087] Instead of mechanically, in particular motor-driven, variable reactances, electrically and / or magnetically variable reactances are also conceivable.

[0088] Figures 7 and 8 each show an exemplary embodiment of a possible configuration of the measuring unit 11. The measuring unit 11 is designed to measure a voltage and a current without contact. For this purpose, the measuring unit 11 comprises a current sensor 16 and a voltage sensor 20.

[0089] The measuring unit 11 can be arranged between the RF generator 3 and the impedance matching circuit A 9, i.e. the cable 5a from Fig. 7 or Fig. 8 can be realized by the second cable connection 6a from one of the figures 2 or 3.

[0090] The measuring unit 11 can be arranged at the input of the impedance matching circuit A 9.

[0091] The measuring unit 11 can be arranged at the output of the RF generator 3. However, the phase relationship between current and voltage is preferably also measured so that, for example, the impedance can be calculated.

[0092] The current sensor 16 of the measuring unit 11 is a coil 21, particularly in the form of a Rogowski coil. Both ends of the coil are preferably connected to each other via a shunt resistor 22. The voltage drop across the shunt resistor 22 can be digitized using a first A / D converter 23.

[0093] The voltage sensor 20 of the measuring unit 11 is preferably designed as a capacitive voltage divider. A first capacitance 24 is formed by an electrically conductive ring 24. An electrically conductive cylinder could also be used. The corresponding first cable connection 6a is routed through this electrically conductive ring 24. A second capacitance 25 of the voltage sensor 20, which is designed as a voltage divider, is connected to the reference ground. A second A / D converter 26 is connected in parallel to the second capacitance 25 and is designed to detect and digitize the voltage drop across the second capacitance 25.

[0094] In principle, the measuring unit 11 can also be arranged or constructed on a single, in particular shared, circuit board. The first capacitor 24 can be formed by a coating on a first and an opposite second side of the circuit board. In this case, the coatings on the first and second sides are electrically connected to one another by vias. The first cable connection 5a is routed through an opening in the circuit board. The second capacitor 25 can be formed by a discrete component.

[0095] The current sensor 16 in the form of the coil 21, particularly in the form of a Rogowski coil, is spaced further from the first cable connection 5a than the first capacitor 24. The coil can also be formed on the same circuit board by appropriate coatings and vias. The coil for current measurement and the first capacitor for voltage measurement preferably extend through a common plane.

[0096] The shunt resistor 22 can also be arranged on this circuit board. The same applies to the first and / or second A / D converters 23, 23. The measuring unit 11 can also be designed as a directional coupler unit.

[0097] In principle, the measuring unit 11 can also be arranged between the impedance matching circuit 3 and the load 5 in the form of the plasma chamber. In this case, the second cable connection 6b would be used for measuring current and voltage, i.e., the cable 5a from Fig. 7 or Fig. 8 would be implemented by the second cable connection 6b from one of Figs. 1, 2, or 3. The input impedance can then be calculated by taking into account a known transformation ratio of the impedance matching circuit 3.

[0098] Figure 9 shows a flowchart for a method explaining the operation of the transformation system 10. The plasma process control system 2 is connected to the impedance matching circuit A 9 via the transformation system 10. In a first method step S 1 , a communication device 14 of the transformation system 10 receives control data B for an impedance matching circuit B 4 from the plasma process control system 2. In a second method step S 2 , the first transformation device 10a transforms the control data B for the impedance matching circuit B 4 into control data A for the impedance matching circuit A 9. In a third method step S 3 , the transformation system 10 makes the transformed control data A available to the impedance matching circuit A 9. In addition to or as an alternative to the method steps S 1 , S 2 , S 3 , the further method steps S 4 , S 5 , S e can also be carried out.In a fourth method step S4, the transformation system 10 receives information data A from the impedance matching circuit A 9. In a fifth method step S5, the first transformation device 10a transforms the received information data A from the impedance matching circuit A 9 into information data B of the impedance matching circuit B 4. In a sixth method step S5, the communication device 14 transmits the information data B to the plasma process control system 2.

[0099] The invention is not limited to the described embodiments. All described and / or illustrated features can be combined within the scope of the invention.

Claims

Claims 1. Transformation system (10) for connecting a plasma process control system (2) to an impedance matching circuit A (9), wherein the impedance matching circuit A (9) is connectable to an RF generator (3) and a plasma chamber (5), wherein the transformation system (10) comprises the following features: - a first transformation device (10a) and a communication device are provided, wherein the communication device (14) is connectable to the plasma process control system (2); wherein: a) - the communication device (14) is designed to receive control data B for an impedance matching circuit B (4), in particular from the plasma process control system (2); - the first transformation device (10a) is designed to transform the control data B for the impedance matching circuit B (4) into control data A for the impedance matching circuit A (9); and - the transformation system (10) is designed to provide the control data A for controlling the impedance matching circuit A (9); and / or b) - the transformation system (10) is designed to receive information data A from the impedance matching circuit A (9); - the first transformation device (10a) is designed to transform the received information data A from the impedance matching circuit A (9) into information data B of the impedance matching circuit B (4); and - the communication device (14) is designed to provide the information data B, in particular to transmit it to the plasma process control system (2).

2. Transformation system (10) according to claim 1, characterized by the following feature: - the transformation system (10) is designed to transmit the control data A to the impedance matching circuit A (9) and thereby control the impedance matching circuit A (9).

3. Transformation system (10) according to claim 1 or 2, characterized by the following feature: - the first transformation device (10a) comprises a transformation table and / or a transformation function in order to transform the control data B for the impedance matching circuit B (4) into control data A for the impedance matching circuit A (9).

4. Transformation system (10) according to one of the preceding claims, characterized by the following feature: - the control data B for the impedance matching circuit B (4) comprise manipulated variables for at least one mechanically, in particular motor-adjustable, reactance in the impedance matching circuit B (4); - the control data A for the impedance matching circuit A (9) comprise manipulated variables for at least one mechanically, in particular motor-driven, adjustable reactance (52, 53) for the impedance matching circuit A (9).

5. Transformation system (10) according to one of the preceding claims, characterized by the following features: - the control data B for the impedance matching circuit B (4) comprise: a) position information; and / or b) capacitance information; for at least one mechanically, in particular motor-driven, adjustable reactance which is arranged in the impedance matching circuit B (4) in order to to provide a specific impedance target value at the output terminal (4b) of the impedance matching circuit B (4); - the first transformation device (10a) is designed to transform the control data B for the impedance matching circuit B (4) into control data A for the impedance matching circuit A (9), wherein the control data A for the impedance matching circuit A (9) comprises position information for at least one mechanically, in particular motor-driven, adjustable reactance (52, 53) which is arranged in the impedance matching circuit A (9), by means of which the same impedance target value can be provided at the output terminal (9b) of the impedance matching circuit A (9) as at the output terminal (4b) of the impedance matching circuit B (4).

6. Transformation system (10) according to one of the preceding claims, characterized by the following feature: - the information data A comprise at least one of the following values: a) current position information for at least one mechanically, in particular motor-adjustable, reactance (52, 53) in the impedance matching circuit A (9); b) current capacitance information for at least one mechanically, in particular motor-adjustable reactance (52, 53) in the impedance matching circuit A (9); c) a currently set transformation ratio in the impedance matching circuit A (9); d) a current efficiency of the impedance matching circuit A (9); e) at least one current value for a voltage and / or current at or in the impedance matching circuit A (9).

7. Transformation system (10) according to one of the preceding claims, characterized by the following feature: - the first transformation device (10a) comprises a transformation table and / or a transformation function in order to transform the information data A for the impedance matching circuit A (9) into information data B for the impedance matching circuit B (4).

8. Transformation system (10) according to one of the preceding claims, characterized by the following features: - the communication device is designed to receive a target generator power B for the RF generator (3) for use by the impedance matching circuit B (4) from the plasma process control system (2); - a second transformation device (10b) is provided, wherein the second transformation device (10b) is designed to transform the target generator power B for use by the impedance matching circuit B (4) into a target generator power A for use by the impedance matching circuit A (9); - the second transformation device (10b) is designed to transmit the target generator power A to the RF generator (3).

9. Transformation system (10) according to claim 8, characterized by the following feature: - the second transformation device (10b) is designed to transform the target generator power B received from the plasma process control system (2) as a function of a variable, wherein the variable can describe an efficiency difference between the impedance matching circuit A (9) and the impedance matching circuit B (4).

10. Transformation system (10) according to claim 8 or 9, characterized by the following features: - the second transformation device (10b) is designed to transform the target generator power B received from the plasma process control system (2) as a function of an efficiency difference between an efficiency of the impedance matching circuit A (9) and an efficiency of the impedance matching circuit B (4), wherein the efficiency of the impedance matching circuit A (9) results when operating with the manipulated variable A and wherein the efficiency of the impedance matching circuit B (4) results when operating with the manipulated variable B.

11. Transformation system (10) according to one of claims 8 to 10, characterized by the following feature: - the second transformation device (10b) is designed to reduce the target generator power B received from the plasma process control system (2) if the efficiency of the impedance matching circuit A (9) is greater than the efficiency of the impedance matching circuit B (4).

12. Transformation system (10) according to one of claims 8 to 11, characterized by the following features: - the second transformation device (10b) is designed to receive an actual generator power from the RF generator (3) with connected impedance matching circuit A (9); wherein: a) the second transformation device (10b) is designed to increase the actual generator power if the efficiency of the impedance matching circuit A (9) is greater than the efficiency of the impedance matching circuit B (4); the communication device is designed to transmit the increased actual generator power to the plasma process control system (2); and / or b) the second transformation device (10) is designed to reduce the actual generator power if the efficiency of the impedance matching circuit A (9) is lower than the efficiency of the impedance matching circuit B (4); the communication device is designed to transmit the reduced actual generator power to the plasma process control system (2).

13. Transformation system (10) according to one of the preceding claims, characterized by the following features: - the communication device (14) is designed to receive a frequency setpoint for the RF generator (3) from the higher-level plasma process control system (2); - the second transformation device (10b) is designed to transmit the frequency setpoint to the RF generator (3) without changing the frequency.

14. Plasma generation system (1) with a transformation system (10) according to one of the preceding claims, an RF generator (3), an impedance matching circuit A (9) and a plasma process control system (2), wherein the plasma generation system (1) comprises the following features: - the plasma process control system (2) is connected to the transformation system; - the RF generator (3) is connected to the impedance matching circuit A (9); - the plasma process control system (2) is connected to the transformation system (10).

15. Plasma generation system (1) according to claim 14, characterized by the following features: - the transformation system (10) is: a) designed as a separate system between the RF generator (3), the impedance matching circuit A (9) and the plasma process control system (2); or b) designed as a module in the RF generator (3) and in the impedance matching circuit A (9); or c) designed as a module in the plasma process control system (2).

16. A method for generating a transformation table and / or a transformation function to transform control data B for the impedance matching circuit B (4) into control data A for the impedance matching circuit A (9), the method comprising the following method steps: - connecting a vector network analyzer (13) to the input terminal (4a) and the output terminal (4b) of the impedance matching circuit B (4); - determining an impedance at the output terminal (4b) for a position for at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B (4); - Changing the position of the at least one mechanically, in particular motor-adjustable, reactance of the impedance matching circuit B (4) and repeating the method step of determining; - connecting one or the vector network analyzer (13) to the input terminal (9a) and the output terminal (9b) of the impedance matching circuit A (9); - determining an impedance at the output terminal (9b) for a position for at least one mechanically, in particular motor-driven, adjustable reactance (52, 53) of the impedance matching circuit A (9); - Changing the position of the at least one mechanically, in particular motor-adjustable, reactance (52, 53) of the impedance matching circuit A (9) and repeating the method step of determining; - Creating a transformation table and / or a transformation function by means of which a position of the at least one mechanically, in particular motor-driven, adjustable reactance of the impedance matching circuit B (4) can be converted into a position for the at least one mechanically, in particular motor-driven, adjustable reactance (52, 53) of the impedance matching circuit A (9), wherein the impedance at the output terminal of the impedance matching circuit A (9): a) is equal to the impedance at the output terminal of the impedance matching circuit B (4); or b) deviates by less than a threshold value.

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