Impedance matching circuit, plasma processing supply system, and plasma processing system

Abstract

The present invention provides an impedance matching circuit (1) for a plasma process supply system, comprising: a) a first impedance matching unit (6) for fixed preset impedance transformation; and b) a second impedance matching unit (7) for adjustable impedance transformation, wherein the second impedance matching unit comprises: i) one or more reactances (C3); ii) a semiconductor switching element (14) for stepwise changing a transformation ratio; and iii) an electrically continuously variable reactance (16) for steplessly changing the transformation ratio; c) the semiconductor switching element and / or the variable reactance are operable up to a maximum allowable voltage / current; and d) the first impedance matching unit (6) is configured to: i) adjust the impedance ( Z 1. Z P ) conductance (G1, G P ) is greater than the conductance of the impedance occurring at the input or output of the second impedance matching unit at the maximum allowable voltage of the semiconductor switching element and / or the variable reactance, and ii) the impedance ( Z 1. Z P ) resistors (R1, R P ) is configured to be greater than the resistance of the impedance occurring at the input or output of the second impedance matching unit at the maximum allowable current of the semiconductor switching element and / or variable reactance.

Description

[Technical Field]

[0001] The present invention relates to an impedance matching circuit, a plasma process supply system and a plasma process system for powers of 500 W or more, preferably 2 kW or more, and frequencies in the range of 2 to 100 MHz, particularly in the range of 10 MHz to 50 MHz. [Background technology]

[0002] Such an impedance matching circuit can be used in systems in which a load is supplied with power, particularly high frequency power. "High frequency" is hereinafter also abbreviated as "HF", where HF refers to frequencies in the range of 2 MHz to 100 MHz, particularly in the range of 10 MHz to 50 MHz.

[0003] In such systems, the impedance of the load must be matched to the impedance of the power source, otherwise power reflections may occur, which have a direct impact on the efficiency of the system and reduce its effectiveness.

[0004] An exemplary system in which an impedance matching circuit may be used is a plasma processing system.

[0005] Such a plasma processing system may be, for example, a system in which power is supplied to a load, such as a plasma processing device.

[0006] Such plasma processing equipment may be, for example, a plasma processing chamber used for industrial plasma processes such as surface treatment of workpieces, semiconductor manufacturing using plasma, or treatment of workpieces using gas lasers.

[0007] In such applications, a plasma processing device is used to generate the plasma.

[0008] To this end, the plasma processing apparatus may include an electrode to which a high frequency power signal (hereinafter referred to as HF power signal) is supplied to generate the plasma.

[0009] Typically, a high power, particularly a high voltage power supply is required, and for this purpose the plasma processing device may be connected to a high frequency power supply (hereinafter referred to as HF power supply).

[0010] Plasma processes performed within a plasma processing apparatus present a problem in that the electrical load impedance of the plasma processing apparatus generated during the process can vary significantly depending on the conditions within the plasma processing apparatus, particularly considering the workpiece characteristics, electrode and gas conditions.

[0011] Therefore, an impedance matching circuit is typically required to transform the impedance of the load to the nominal impedance of the HF power source, and such an impedance matching circuit is typically located between the HF power source and the plasma processing device, typically in close proximity to the plasma processing device.

[0012] An impedance matching circuit is typically a device that may include inductors and / or capacitors.

[0013] For complex problems where being able to quickly change impedance is important, semiconductor switched impedance matching circuits are often used. These semiconductor switching elements can be used to connect and disconnect inductors and / or capacitors in the impedance matching circuit. A control circuit can be used to control the connection and disconnection by the semiconductor switching elements. An example of such a semiconductor switched impedance matching circuit is disclosed and described in German Utility Model No. 202020102084 (DE202020102084U1).

[0014] Such semiconductor switched impedance matching circuits inherently have only a discrete set of possible output impedances at a given frequency. However, it is desirable to have as fine a tuning as possible. This requires a relatively large number of semiconductor switches. However, this contradicts the need for as compact a design as possible. Because space within such plasma processing systems is often limited, as compact a design as possible is generally desired. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] German Utility Model Registration No. 202020102084 (DE202020102084U1) Summary of the Invention [Problem to be solved by the invention]

[0016] The invention is therefore based on the object of providing an impedance matching circuit which increases the number of possible output impedances, allows a continuously variable output impedance for at least one range, and makes more advantageous use of the components used, thus allowing a compact design. [Means for solving the problem]

[0017] This object is achieved by an impedance matching circuit according to independent claim 1. Advantageous further developments of the invention arise from the dependent claims and / or the description.

[0018] According to the invention, an impedance matching circuit is proposed, in particular for plasma process supply systems and plasma process systems, for powers of 500 W or more and frequencies in the range of 2 MHz to 100 MHz, the impedance matching circuit comprising: a) a first impedance matching unit configured to perform a first predetermined impedance transformation from its input terminal to its output, the first impedance matching unit comprising one or more reactances; b) a second impedance matching unit configured to perform a second predetermined impedance transformation from its input terminal to its output with an adjustable transformation ratio; Equipped with The second impedance matching unit comprises: i) one or more reactances; ii) a semiconductor switching element, the semiconductor switching element being capable of changing the conversion ratio in predetermined steps during operation by the semiconductor switching element; iii) a continuously variable electrical reactance, which allows the transformation ratio to be varied steplessly during operation; and Equipped with c) the semiconductor switching element and / or the continuously variable electrical reactance are operable up to the maximum permissible voltage and maximum permissible current; d) the first impedance matching unit comprises: i) the conductance of the impedance at the input or output of the second impedance matching unit is greater than the conductance of the impedance occurring at the input or output of the second impedance matching unit at the rated power of the impedance matching unit and the maximum allowable voltage of the at least one semiconductor switching element and / or electrically continuously variable reactance; and ii) so that the resistance of the impedance at the input or output of the second impedance matching unit is greater than the resistance of the impedance occurring at the input or output of the second impedance matching unit at the rated power and maximum allowable current of the at least one semiconductor switching element and / or electrical continuously variable reactance; The impedance transformer is configured to perform a first predetermined impedance transformation.

[0019] As mentioned above, a semiconductor switched impedance matching circuit has only a discrete set of possible output impedances. If the design of the impedance matching circuit is to be as compact as possible, it is important to keep the number of semiconductor switching elements low. On the one hand, this means that these semiconductor switching elements should not be constructed from parallel and / or series connections of multiple switching components.

[0020] Secondly, this means that the steps between adjustable values ​​can be very large.

[0021] Because of all these limitations, it is not possible to trim the reflection coefficient to zero for all plasma impedance values, since available discrete impedances cannot transform all complex impedances to have a zero reflection coefficient. However, reflected power is a common measure of the quality of the power match in plasma applications. Therefore, making it zero is often necessary for product acceptance in this market.

[0022] Furthermore, semiconductor switch impedance matching circuits suffer from the problem that the current and voltage carrying capabilities of the semiconductor switches are insufficient depending on the load conditions. The current and voltage carrying capabilities of the actual semiconductor switches determine the maximum power that can be transmitted by such impedance matching circuits. It has been shown that there is no suitable impedance for utilizing both the current and voltage limits of the semiconductor switching elements in both switching positions, both in 50 ohm systems and plasma processing chambers. In principle, it can be said that the semiconductor switching elements are not switching within their optimal ranges.

[0023] If the current and / or voltage is too low, the semiconductor switching elements may not be fully controlled, or if the current and voltage are too high, the semiconductor switching elements may be damaged. The latter case should be avoided, and therefore semiconductor switches are never fully utilized in the prior art.

[0024] The dimensioning of the impedance matching circuit according to the present invention, determined by calculations, simulations, circuit design, tests, and investigations, ensures that the at least one semiconductor switching element is fully utilized but not overloaded. It has been found that the impedance matching unit must meet the above-mentioned criteria for transforming the input impedance into an intermediate impedance, which is preferably constant and more preferably corresponds to 50 ohms. This, along with the maximum allowable voltage and current of the semiconductor switching elements, allows for accurate calculation of the transformation ratio set by the first impedance matching unit. The at least one semiconductor switching element is not overloaded and switches currents and voltages below the maximum allowable values. This means that the at least one semiconductor switching element is fully controlled, which means that the semiconductor switching element does not need to be oversized, thereby reducing costs. The dimensioning ensures that no critical situations arise regarding the current carrying capacity and dielectric strength of the at least one semiconductor switching element. In particular, the impedance matching circuit according to the present invention makes it possible to eliminate the need to connect multiple semiconductor switching elements in parallel and / or in series with each other. This is advantageous because the effort required to actually switch multiple semiconductor switching elements simultaneously would be very large. If one semiconductor switching element switches slightly later than the other semiconductor switching elements, this could lead to destruction of the impedance matching circuit. However, this is effectively avoided by the dimensioning according to the present invention. This dimensioning ensures that the at least one semiconductor switching element does not experience an operating condition that could destroy it, especially at a given input impedance predetermined by the HF power source. The at least one semiconductor switching element only needs to switch a current and / or voltage below the maximum allowable voltage and / or current. Therefore, no additional control loop is required to measure the voltage and / or current and make the switching behavior dependent thereon.As a result, the semiconductor switching elements do not have to be significantly oversized as in impedance matching circuits from the prior art, which makes the impedance matching circuit according to the invention cheaper to manufacture.

[0025] Complex Impedance Z In the case of the term "conductance" in, in general, the conductance is a real number and must be equal to G, with the following relationship: Z =1 / Y =1 / (G+jB).

[0026] Therefore, the intermediate impedance Z The conductance of 1 is G1, which is given by: Z 1=1 / Y 1=1 / (G1+jB1)

[0027] Therefore, the output impedance Z P The conductance of G P and is as follows: Z P =1 / Y P =1 / (G P +jB P )

[0028] B, B1, B P is the complex conductance Y , Y 1. Y P is the imaginary part of

[0029] Complex Impedance Z Regarding the term "resistance" in, in general, resistance is a real number and must be equal to R, with the following relationship: Z =R+jX

[0030] Therefore, the intermediate impedance Z The resistor 1 is R1, which is as follows: Z 1=R1+jX1

[0031] Therefore, the output impedance Z P The resistance of R P and is as follows: Z P =R P +jX P

[0032] X, X1, X P is the complex impedance Z , Z 1. Z P is the imaginary part of

[0033] In a preferred embodiment, the first impedance matching unit is configured so that the conductance of the impedance at the input of the second impedance matching unit is greater than the conductance of the impedance occurring at the input of the second impedance matching unit at the rated power of the impedance matching unit and the maximum allowable voltage of the at least one semiconductor switching element and / or electrically continuously variable reactance, and so that the resistance of the impedance at the input of the second impedance matching unit is greater than the resistance of the impedance occurring at the input of the second impedance matching unit at the rated power and the maximum allowable current of the at least one semiconductor switching element and / or electrically continuously variable reactance.

[0034] By using a continuously variable electrical reactance in the impedance matching circuit, the number of possible output impedances can be increased and an output impedance that is steplessly variable, at least over a certain range, can be achieved.

[0035] The upper end of this particular range may advantageously be limited by the impedance of the impedance matching circuit to the largest possible impedance of the continuously variable electrical reactance without adding additional continuously variable electrical reactance, and the lower end of the range may advantageously be limited by the impedance of the impedance matching circuit to the smallest possible impedance of the continuously variable electrical reactance without adding additional continuously variable electrical reactance.

[0036] The maximum and minimum possible impedances of a continuously variable electrical reactance are component dependent. A continuously variable electrical reactance can be infinitely adjusted between these two limits. The impedance can be adjusted, for example, by applying a control voltage.

[0037] The continuously variable electrical reactance can be implemented either as a continuously variable electrical capacitor or as a continuously variable electrical inductor. The continuously variable electrical capacitor can be, for example, a varactor. The continuously variable electrical inductor can be, for example, a transducer. A transducer is understood here to mean an electromagnetic component for controlling an alternating current by means of an electrical signal, in particular a direct current, in particular by pre-magnetizing the magnetic core of a choke.

[0038] In an advantageous embodiment of the impedance matching circuit, the input impedance is substantially constant during operation of the impedance matching circuit and is equal to a predetermined target input impedance. On the one hand, this provides a constant impedance to the HF power source, and on the other hand, the constant transformation ratio of the input impedance to the intermediate impedance by the first impedance matching unit ensures that the at least one semiconductor switching element is always operated within acceptable limits and at a high level of modulation.

[0039] In one embodiment, the first impedance matching unit of the impedance matching circuit can be implemented with only a fixed reactance, which is cost-effective and robust.

[0040] In one embodiment, the impedance matching unit may comprise a plurality of semiconductor switching elements and one, in particular a plurality of control circuits associated with each of the semiconductor switching elements, each configured to connect and disconnect a reactance, thereby enabling a wide range of impedance matching to be covered and at the same time achieving a compact design.

[0041] In one embodiment, the at least one semiconductor switching element of the second impedance matching unit may be a transistor or a diode, which allows the conversion ratio to be changed particularly quickly during operation.

[0042] The transistors can be designed as metal oxide semiconductor field effect transistors (MOSFETs), and the switching diodes can be designed as PIN diodes, for example.

[0043] The at least one semiconductor switching element can also be cooled by a fluid. The fluid can be, for example, water, including distilled water. For cooling, the semiconductor switching element can be arranged on a cooling body. The cooling body can be made of, in particular, a metal, for example, aluminum and / or copper. The cooling body can further comprise at least one channel through which a fluid can flow to dissipate heat from the semiconductor switching element.

[0044] In one embodiment, the impedance matching circuit may be used in a plasma process delivery system or a plasma process system.

[0045] Such a plasma processing supply system may include an HF power supply for providing an HF power signal, in addition to an impedance matching circuit, which may be electrically connected to the HF power supply and may be designed to be connected to a plasma processing apparatus.

[0046] In a plasma processing system, such a plasma processing device may be present and connected to a plasma processing supply system through which the plasma processing device may be powered from an HF power signal.

[0047] Preferred exemplary embodiments of the invention are shown diagrammatically in the drawings and are explained in more detail below with reference to the drawings. [Brief explanation of the drawings]

[0048] [Figure 1] 1 shows a schematic diagram of a first embodiment of a plasma processing system having an impedance matching circuit according to the present invention; [Figure 2a] 3A-3C show various embodiments of a first impedance matching unit of an impedance matching circuit according to the present invention; [Figure 2b] 3A-3C show various embodiments of a first impedance matching unit of an impedance matching circuit according to the present invention; [Figure 3a] 5A-5C show various embodiments of a second impedance matching unit of an impedance matching circuit according to the present invention; [Figure 3b] 5A-5C show various embodiments of a second impedance matching unit of an impedance matching circuit according to the present invention; [Figure 3c] 5A-5C show various embodiments of a second impedance matching unit of an impedance matching circuit according to the present invention; [Figure 3d] 5A-5C show various embodiments of a second impedance matching unit of an impedance matching circuit according to the present invention; [Figure 3e] 5A-5C show various embodiments of a second impedance matching unit of an impedance matching circuit according to the present invention; [Figure 3f] 5A-5C show various embodiments of a second impedance matching unit of an impedance matching circuit according to the present invention; [Figure 4a]1 illustrates various embodiments of a continuously variable electrical reactance. [Figure 4b] 1 illustrates various embodiments of a continuously variable electrical reactance. [Figure 4c] 1 illustrates various embodiments of a continuously variable electrical reactance. [Figure 4d] 1 illustrates various embodiments of a continuously variable electrical reactance. [Figure 5] 1 illustrates an embodiment of a measurement unit of a plasma process delivery system. [Figure 6] 1 shows a portion of a measurement unit of a plasma processing system. DETAILED DESCRIPTION OF THE INVENTION

[0049] 1 shows a plasma processing system 100 comprising a plasma processing supply system 108. The plasma processing supply system 108 comprises an impedance matching circuit 1 according to the invention and an HF power source 101. The plasma processing supply system 108 is configured to be connected to at least one consumer 102, in particular a plasma processing device, for example in the form of a plasma processing chamber. When connected to the consumer 102 as shown in FIG. 1, the plasma processing supply system 108 is completed to form the plasma processing system 100. The HF power source 101 supplies a nominal power P rated The impedance matching circuit 1 is configured to provide an HF signal having an input terminal 2 to which an HF power supply 101 is connected. The impedance matching circuit 1 further includes an output terminal 3.

[0050] The output terminal 3 is connected to at least one consumer 102. The HF power supply 101 is preferably connected to the impedance matching circuit 1 via a first cable arrangement 4. The impedance matching circuit 1 is preferably connected to the consumer 102 via a second cable arrangement 5. The first and / or second cable arrangement 4, 5 may, for example, comprise one or more cables connected in series and / or in parallel. Preferably, coaxial cables are used.

[0051] The consumer 102, here a plasma processing device in the form of a plasma processing chamber, includes at least one electrode 103 for generating a plasma 104. The electrode 103 is connected to the output terminal 3 of the impedance matching circuit 1.

[0052] The plasma process supply system 108 also includes a control and / or detection device 105, which may preferably include a processor and / or a programmable logic component, in particular an FPGA and / or a microcontroller and / or a preconfigured logic component, in particular an ASIC. The control and / or detection device 105 may also include a memory unit. The control and / or detection device 105 is configured to control the HF power supply 101, in particular to activate or deactivate it. Additionally or alternatively, the control and / or detection device 105 is also configured to change the power and / or frequency of the HF signal. Additionally or alternatively, the control and / or detection device 105 is configured to change the waveform, in particular the type of HF signal, or the modulation of the HF signal.

[0053] The control and / or detection device 105 is preferably also configured to control the impedance matching circuit 1. In particular, the control and / or detection device 105 is configured to change the transformation ratio in the impedance matching circuit 1.

[0054] Preferably, the plasma process supply system 108 also includes a measurement unit 106. The measurement unit 106 is disposed between the HF power source 101 and the impedance matching circuit 1. The measurement unit 106 may include, for example, at least one directional coupler or a current sensor and a voltage sensor. Through the at least one directional coupler, the measurement unit 106 can measure the power of the HF signal transmitted from the HF power source 101 toward the impedance matching circuit 1. Preferably, the measurement unit 106 can also measure the power of the HF signal reflected by the impedance matching circuit 1 and returning toward the HF power source 101. The power of the HF signal transmitted from the HF power source 101 toward the impedance matching circuit 1 can also be determined through the current sensor and the voltage sensor. The power of the HF signal reflected by the impedance matching circuit 1 can also be detected by the current sensor and the voltage sensor.

[0055] The plasma process supply system 108 also preferably comprises an operation unit 107. The operation unit 107 preferably has a screen, in particular a touch screen. In addition to the screen, the operation unit 107 may also comprise input means such as a keyboard and / or a mouse. The operation unit 107 may be a web server that provides data and receives user input. The control and / or detection device 105 is configured to display the current settings of the HF power supply 101 and / or the impedance matching circuit 1 on the operation unit 107. The control and / or detection device 105 may also be designed to display measured values ​​received by the measurement unit 106 on the operation unit 107. The control and / or detection device 105 is preferably configured to receive setpoint specifications, for example for the power of the HF signal, the frequency of the HF signal, and / or the waveform of the HF signal, from the operation unit 107, generate corresponding operating variables for the HF power supply 101, and transmit them to the latter.

[0056] Before describing the impedance matching circuit 1 according to the invention in detail, reference is made to Figures 5 and 6 which illustrate the measurement unit 106. In this exemplary embodiment, the measurement unit 106 is configured to measure voltage and current contactlessly. For this purpose, the measurement unit 106 comprises a current sensor 110 and a voltage sensor 111, which are shown in detail in Figures 5 and 6.

[0057] However, preferably the phase relationship between current and voltage is still measured.

[0058] The current sensor 110 of the measurement unit 106 is a coil, in particular in the form of a Rogowski coil.

[0059] The ends of the coil are connected via a shunt resistor 112. The voltage dropped across the shunt resistor 112 can be digitized by a first A / D transducer 113.

[0060] The voltage sensor 111 of the measuring unit 106 is preferably constructed as a capacitive voltage divider. A first capacitor 114 is formed by a conductive ring 114. A conductive cylinder can also be used. The first cable arrangement 4 is guided through this conductive ring 114. A second capacitor 115 of the voltage sensor 111 configured as a voltage divider is connected to a reference ground. A second A / D transducer 116 is connected in parallel to the second capacitor 115 and is configured to detect and digitize the voltage drop across the second capacitor 115.

[0061] In principle, the measurement unit 106 can also be arranged or constructed on a (common) circuit board. The first capacitor 114 can be formed by a coating on a first side and an opposite second side of the circuit board. In this case, the coatings on the first and second sides are electrically connected to each other by vias. The first cable arrangement 4 is guided through an opening in the circuit board. The second capacitor 115 can be composed of discrete components.

[0062] The current sensor 110 in the form of a coil, in particular a Rogowski coil, is further away from the first cable arrangement 4 than the first capacitor 114. The coil can also be formed on the same circuit board with corresponding coatings and vias. The coil for current measurement and the first capacitor for voltage measurement preferably run in a common plane.

[0063] The shunt resistor 112 may also be located on this circuit board. The same applies to the first and / or second A / D transducers 113, 116. The first and / or second A / D transducers 113, 116 are read out and / or controlled by the control and / or detection device 105.

[0064] The control and / or detection device 105 is preferably configured to control the impedance matching circuit 1 based on the measurements of the measurement unit 106 .

[0065] 1 again, the structure of the impedance matching circuit 1 will be described in more detail below. The impedance matching circuit 1 includes a first impedance matching unit 6 and a second impedance matching unit 7. The first impedance matching unit 6 is electrically connected to the input terminal 2.

[0066] The first impedance matching unit 6 matches the input impedance applied to the input terminal 2. Z 0 is the intermediate impedance Z It is configured to convert to 1. Intermediate impedance Z1 is applied to the output 9 of the first impedance matching unit 6. The transformation ratio cannot be changed during operation. In Fig. 1, the first impedance matching unit 6 comprises an inductor L2 and a capacitor C2 connected in an L-shape. Many other designs are possible, and some are shown by way of example in Figs. 2a and 2b. The second impedance matching unit 7 is connected to the first impedance matching unit 6 in the transmission direction of the HF signal from the HF source 101 to the consumer 102. In particular, the second impedance matching unit 7 has an input 10 which is connected to the output 9 of the first impedance matching unit 6 or which is connected directly to the output 9. The input 10 therefore has an intermediate impedance Z 1 is also present. The second impedance matching unit 7 has an intermediate impedance at its input 10 Z 1, the output impedance at output terminal 3 Z P The conversion ratio can be changed during operation by at least one semiconductor switching element 14. The second impedance matching unit 7 in Fig. 1 includes, as an example, a continuously variable electrical reactance 16 connected in parallel to the series connection of the capacitor C3 and the semiconductor switching element 14.

[0067] At least one semiconductor switching element 14 of the second impedance matching unit 7 can be operated up to the maximum allowable voltage and maximum allowable current. Z Intermediate impedance that converts 0 Z 1 is, for a given target input impedance, a) Intermediate Impedance Z The conductance G1 of the impedance matching circuit 1 is rated and at the maximum allowable voltage of the at least one semiconductor switching element 14, the conductance of the impedance occurring at the input 10 of the second impedance matching unit 7 is greater than the conductance of the impedance; b) Intermediate Impedance Z Resistor R1 has a rated power Prated and so as to be greater than the resistance of the impedance appearing at the input 10 of the second impedance matching unit 7 at the maximum allowable current of the at least one semiconductor switching element 14; be selected.

[0068] Rated power P of impedance matching circuit 1 rated is the rated power P of the HF power supply 101 rated It is preferably the same as

[0069] A transmission path for transmitting an HF signal is provided between the input terminal 2 and the output terminal 3 of the impedance matching circuit 1. First and second impedance matching units 6 and 7 are arranged on the transmission path.

[0070] Possible structures of the first and second impedance matching units 6, 7 of the impedance matching circuit 1 are explained in more detail in the following figures.

[0071] 2a and 2b show two different circuit diagrams of the first impedance matching unit 6, which in these exemplary embodiments does not have a semiconductor switching element 14.

[0072] 2a shows an embodiment of an L-shaped first impedance matching unit 6 having an inductor L2a and a capacitor C2a. The inductor L2a is connected from the input terminal 2 to ground. The capacitor C2a is connected between the input terminal 2 and the output 9 of the first impedance matching unit 6. This first impedance matching unit 6 matches the input impedance at the input terminal 2 to Z 0, the intermediate impedance at its own output 9 Z It is configured to convert to 1.

[0073] 2b shows a further embodiment of a π-type first impedance matching unit 6, which comprises an inductor L2b and two capacitors C2b, C2b'. The inductor L2b is connected from the input terminal 2 to ground. The capacitor C2b is connected between the input terminal 2 and the output 9 of the first impedance matching unit 6. The capacitor C2b' is connected from the output 9 to ground.

[0074] This first impedance matching unit 6 matches the input impedance at the input terminal 2 Z 0, the intermediate impedance at its own output 9 Z It is configured to convert to 1.

[0075] Figures 3a to 3f show various circuit diagrams of the second impedance matching units 7a to 7f, which in these exemplary embodiments are comprised of one or more semiconductor switching elements 14a to 14f and one or more control circuits 15a to 15f. The second impedance matching units 7a to 7f further comprise a first terminal 11 and a second terminal 12, to which a continuously variable electrical reactance 16 is connected (shown in Figures 4a to 4d). Possible embodiments and functions of this continuously variable electrical reactance 16 will be discussed in more detail in the description of Figures 4a to 4d.

[0076] FIG. 3a shows an embodiment of an L-shaped second impedance matching unit 7a having an inductor L3a and two capacitors C3a, C3a'. The inductor L3a is connected between the input 10 and the output terminal 3. The capacitors C3a, C3a' are connected in series, and this series connection is connected from the input 10 to ground. The capacitor C3a' is connected directly to ground. A semiconductor switching element 14a is connected in parallel with the capacitor C3a'. An electrically continuously variable reactance 16 (shown in FIGS. 4a to 4d) is also connected in parallel with the capacitor C3a' and the semiconductor switching element 14a.

[0077] The semiconductor switching element 14a is connected to a control circuit 15a configured to switch the semiconductor switching element 14a on and off. When the semiconductor switching element 14a is switched on, the capacitor C3a' and the continuously variable electrical reactance 16 are shorted, and the resulting capacitance of the series connection is equal to that of the capacitor C3a. When the semiconductor switching element 14a is off, the capacitor C3a' is not shorted, and the impedance of the series connection is equal to the impedance of the series connection of the capacitor C3a and the parallel connection of the capacitor C3a' and the continuously variable electrical reactance 16.

[0078] This second impedance matching unit 7a has an intermediate impedance at its input 10 Z 1 is the output impedance at output terminal 3 Z P The conversion ratio can be varied during operation by a semiconductor switching element 14a and a continuously variable electrical reactance 16.

[0079] FIG. 3b shows a further embodiment of a second impedance matching unit 7b having two capacitors C3b and C3b'. The capacitor C3b is connected in series with a semiconductor switching element 14b. This series connection of the capacitor C3b and the semiconductor switching element 14b is connected between the input 10 and the output terminal 3. The capacitor C3b' is connected in parallel with the semiconductor switching element 14b. Furthermore, a continuous electrical reactance 16 (shown in FIGS. 4a to 4d) is connected in parallel with the capacitor C3b' and the semiconductor switching element 14b via two terminals 11 and 12. The semiconductor switching element 14b is connected to a control circuit 15b configured to switch the semiconductor switching element 14b on and off. When the semiconductor switching element 14b is turned on, the capacitor C3b' and the continuously variable electrical reactance 16 are short-circuited, and the capacitance of the second impedance matching unit 7b becomes equal to that of the capacitor C3b. When the semiconductor switching element 14b is switched off, the capacitor C3b' is not short-circuited and the resulting impedance of the second impedance matching unit 7b is equal to the impedance of the series connection of the capacitor C3b and the parallel connection of the capacitor C3b' and the electrically continuously variable reactance 16.

[0080] This second impedance matching unit 7b has an intermediate impedance at its input 10 Z 1 is the output impedance at output terminal 3 Z P The conversion ratio can be varied during operation by semiconductor switching element 14b and continuously variable electrical reactance 16.

[0081] Figure 3c shows a further embodiment of a second impedance matching unit 7c, which comprises a series connection of two second impedance matching units 7a, 7b from Figures 3a and 3b. This series connection is connected between the input 10 and the output terminal 3. The function of the second impedance matching unit 7c, i.e. the series connection of the two second impedance matching units 7a, 7b, follows the function of the individual impedance matching units 7a, 7b described in the description of Figures 3a and 3b, only when combined as a series connection.

[0082] This second impedance matching unit 7c has an intermediate impedance at its input 10 Z 1 is the output impedance at output terminal 3 Z P The conversion ratio can be varied during operation by semiconductor switching elements 14a, 14b and a continuously variable electrical reactance 16.

[0083] FIG. 3d shows a further embodiment of an L-shaped second impedance matching unit 7d, comprising an inductor L3d, a capacitor C3d, three additional capacitors C3d', and three semiconductor switching elements 14d. The inductor L3d is connected between the input 10 and the output terminal 3. The capacitor C3d is connected in series with a parallel connection of three additional capacitors C3d' and three semiconductor switching elements 14d. This parallel connection has three parallel-connected series connections of the capacitor C3d' and the semiconductor switching elements 14d, and a continuously variable electrical reactance 16 connected in parallel thereto (shown in FIGS. 4a to 4d). Each semiconductor switching element 14d is connected to a control circuit 15d configured to switch the semiconductor switching element 14d on and off. When one of the three semiconductor switching elements 14d is switched on, the capacitor C3d is connected in series with the parallel connection of one of the three capacitors C3d' and the continuously variable electrical reactance 16. This series connection is connected from the input 15 to ground. If one or both of the further semiconductor switching elements 14d are also switched on, then capacitor C3d is connected in series with a parallel connection of two or three capacitors C3d' and the continuously variable electrical reactance 16. This parallel connection can be extended with further parallel-connected series connections, but it is also possible to have only two parallel-connected series connections and the continuously variable electrical reactance 16. When all semiconductor switching elements 14d are switched off, a series connection of capacitor C3d and the continuously variable electrical reactance 16 results. This series connection is connected from input 10 to ground.

[0084] This second impedance matching unit 7d has an intermediate impedance at its input 10 Z 1 is the output impedance at output terminal 3 Z P The conversion ratio can be changed during operation by semiconductor switching element 14d and continuously variable electrical reactance 16.

[0085] FIG. 3e shows a further embodiment of an L-shaped second impedance matching unit 7e, which comprises the second impedance matching unit 7d of FIG. 3d. In addition to the second impedance matching unit 7d described in the description of FIG. 3d, this second impedance matching unit 7e now comprises an additional inductor L3e, an additional semiconductor switching element 14e, additional terminals 11′, 12′ for a continuously variable electrical reactance, and an additional continuously variable electrical reactance 16. The inductor L3e is connected in series with the semiconductor switching element 14e. This series connection is connected in parallel with the inductor L3d. Furthermore, an additional continuously variable electrical capacitor 16 (not shown) is connected in parallel with this series connection and the inductor L3d. The additional continuously variable electrical reactance 16 is connected to the terminals 11′, 12′.

[0086] The semiconductor switching element 14e is connected to a control circuit 15e that is configured to switch the semiconductor switching element 14e on and off. When the semiconductor switching element 14e is switched on, the two inductors L3e, L3d and an additional electrically continuously variable reactance 16 are connected in parallel.

[0087] When the semiconductor switching element 14e is switched off, the inductor L3e has no effect on the impedance of the second impedance matching unit 7e, which corresponds to the second impedance matching unit 7d in FIG. 3d, and the inductor L3d is connected in parallel with the additional electrically continuously variable reactance 16.

[0088] This second impedance matching unit 7e has an intermediate impedance at its input 10 Z 1 is the output impedance at output terminal 3 Z P The conversion ratio can be changed during operation by semiconductor switching elements 14d, 14e and a continuously variable electrical reactance 16.

[0089] FIG. 3f shows a further embodiment of an L-shaped second impedance matching unit 7f, including an inductor L3f, three additional capacitors C3f′, and three semiconductor switching elements 14f. The three semiconductor switching elements 14f are configured as PIN diodes. The inductor L3f is connected between the input 10 and the output terminal 3. The semiconductor switching elements 14f are each connected in series with a capacitor C3f′. These three series connections are connected in parallel. A continuously variable electrical reactance 16 (not shown) is also connected in parallel to these series connections. This entire parallel connection can be expanded with additional parallel-connected series connections, but it is also possible to have only two parallel-connected series connections and the continuously variable electrical reactance. Each semiconductor switching element 14f is connected to a control circuit 15f configured to switch the semiconductor switching element 14f on and off. When one of the three semiconductor switching elements 14f is switched on, one of the three capacitors C3f′ is connected in parallel with the continuously variable electrical reactance 16. This parallel connection is connected from the input 10 to ground. When one or two other semiconductor switching elements 14f are also switched on, the parallel connection of two or three capacitors C3f' and the continuously variable electrical reactance 16 is connected from the input 10 to ground. When all semiconductor switching elements 14f are switched off, the capacitors C3f' have no effect and the continuously variable electrical reactance 16 is switched from the input 10 to ground.

[0090] This second impedance matching unit 7f has a first intermediate impedance at its input 10 Z 1 is the output impedance at output terminal 3 Z P The conversion ratio can be changed during operation by semiconductor switching element 14f and continuously variable electrical reactance 16.

[0091] The impedance matching units 6, 7a to 7f described above can be modified so that inductors can be used instead of capacitors, or so that capacitors can be used instead of inductors, depending on the desired matching.

[0092] The aforementioned impedance matching units 6, 7a to 7f can be used individually or in combination of two or more.

[0093] Figures 4a to 4d show a selection of different embodiments of continuously variable electrical reactances 16, which are configured to be connected via first and second terminals 11, 12 of the second impedance matching units 7, 7a to 7f.

[0094] FIG. 4a shows a configuration in which a continuously variable electrical reactance 16 is connected in parallel to a parallel connection of a plurality of series connections of capacitors C4a and semiconductor switching elements 14.

[0095] Such a parallel connection has already been shown by way of example in FIGS. 3d and 3e.

[0096] 4b shows a possible embodiment of the continuously variable electrical reactance 16. The continuously variable electrical reactance 16 has a first terminal 11, a second terminal 12, a control terminal 13, two capacitors C4b and C4b', two inductors L4b and L4b', and a varactor Vb. The first terminal 11 is connected to the capacitor C4b. The control terminal 13 is connected to the inductor L4b'.

[0097] The inductor L4b' and the capacitor C4b are further connected to each other and to the cathode of the varactor Vb via a node. The anode of the varactor Vb is connected to the capacitor C4b' and the inductor L4b via a node. The capacitor is further connected to the second terminal 12. The inductor L4b is connected to ground.

[0098] The varactor Vb can be used to vary the capacitance by varying the applied voltage.

[0099] The two capacitors C4b, C4b' and the two inductors L4b, L4b' can be used as an HF blocking filter. To this end, the capacitors C4b, C4b' can be sized so that the capacitance for the connection from the first terminal 11 to the second terminal 12 is determined substantially only by the varactor Vb, while at the same time, a uniform voltage applied to the control terminal 13 does not affect the first terminal 11 or the second terminal 12. To this end, the two inductors L4b, L4b' can also be sized so that the HF signal transmitted from the first terminal 11 to the second terminal 12 does not affect the control terminal 13, which is connected to ground only via the inductor L4b', which has a very high impedance.

[0100] Figure 4c shows an embodiment substantially similar to the continuously variable electrical reactance 16 of Figure 4b, in which only the varactor Vb is replaced by a transistor T. Using appropriate control, the change in capacitance can also be achieved via this transistor T, in particular by keeping the transistor T off.

[0101] FIG. 4d shows a further embodiment of the continuously variable electrical reactance 16. The continuously variable electrical reactance 16 has a first terminal 11, a second terminal 12, a control terminal 13, eight varactors Vd1 to Vd8, and five inductors L4d to L4d'''. The varactors Vd1 to Vd8 are interconnected in parallel and series connections. By connecting these eight varactors Vd1 to Vd8 in different ways, it is possible to achieve a significantly larger possible capacitance change than, for example, with a single varactor. The varactors Vd1 to Vd8 have the same function as the varactor Vb in FIG. 4b and can each be replaced by a transistor T, as shown in FIG. 4c. The five inductors L4d to L4d''' have the same function as the two inductors L4b and L4b' in FIGS. 4b and 4c. The two capacitors C4d and C4d' have the same function as the two capacitors C4b and C4b' in FIGS. 4b and 4c.

[0102] With such a configuration, the HF signal transmitted from the first terminal 11 to the second terminal 12 is distributed to the eight varactors Vd1 to Vd8. The continuously variable electrical reactance 16 can therefore operate at higher currents and higher voltages. However, it can also be seen how it can be advantageously used if the conditions for the impedance transformation of the first impedance matching unit 6 can be used to transition from the continuously variable electrical reactance 16 according to Fig. 4d to one according to Fig. 4b or 4c.

Claims

1. An impedance matching circuit (1) for a plasma process supply system (108) and a plasma process system (100), particularly for a power of 500 W or more and a frequency in the range of 2 to 100 MHz, comprising: a) a first impedance matching unit (6) including one or more reactances (C2, C2a, L2a, C2b, C2b', L2, L2b), the first impedance matching unit (6) being configured to perform a first predetermined impedance transformation from its input terminal (2) to its output (9); b) a second impedance matching unit (7, 7a to 7f) configured to perform a second predetermined impedance transformation from its input terminal (10) to its output terminal (3) with an adjustable transformation ratio; Equipped with The second impedance matching unit includes: i) one or more reactances (C3, C3a, C3a', L3a, C3b, C3b', C3d, C3d', L3d, L3e, C3f', L3f); ii) semiconductor switching elements (14, 14a-f), wherein the conversion ratio is variable in predetermined steps by the semiconductor switching elements (14, 14a-f) during operation; iii) a continuously variable electrical reactance (16), wherein the transformation ratio is steplessly variable during operation by the continuously variable electrical reactance (16); Equipped with c) the semiconductor switching elements (14, 14a-f) and / or the electrically continuously variable reactance (16) are operable up to a maximum allowable voltage and a maximum allowable current; d) the first impedance matching unit (6) i) the conductance (G １ , G Ｐ ) is greater than the conductance of the impedance occurring at the input or output of the second impedance matching unit (7, 7a-f) at the rated power of the impedance matching unit and the maximum allowable voltage of the at least one semiconductor switching element (14, 14a-14f) and / or the electrically continuously variable reactance (16), and ii) the resistance (R １ , R Ｐ ) is greater than the resistance of the impedance occurring at the input or output of the second impedance matching unit at the rated power and the maximum allowable current of the at least one semiconductor switching element (14) and / or the continuously variable electrical reactance (16), An impedance matching circuit (1) configured to perform the first predetermined impedance transformation.

2. 2. The impedance matching circuit (1) according to claim 1, characterized in that the input impedance (Z0) is substantially constant during operation of the impedance matching circuit (1) and is equal to a predetermined target input impedance.

3. 2. The impedance matching circuit (1) according to claim 1, wherein the first impedance matching unit (6) is implemented as a first impedance matching unit (6) having only a fixed reactance.

4. 2. The impedance matching circuit (1) according to claim 1, comprising a plurality of semiconductor switching elements (14, 14a-f) and one, in particular a plurality of control circuits (15a-f) associated with each of the semiconductor switching elements, each of the semiconductor switching elements being configured to connect and disconnect a reactance (C3a', C3b', C3d', C3f', L3e).

5. The impedance matching circuit (1) according to any one of claims 1 to 4, characterized in that the at least one semiconductor switching element (14, 14a to 14f) of the second impedance matching unit (7, 7a to 7f) is a transistor or a diode.

6. The impedance matching circuit (1) according to any one of claims 1 to 5, characterized in that the at least one semiconductor switching element (14, 14a to 14f) of the second impedance matching unit (7, 7a to 7f) can be cooled by a fluid.

7. an HF power source (101) for supplying an HF power signal; An impedance matching circuit (1) according to any one of claims 1 to 6, A plasma process delivery system (108) comprising: The impedance matching circuit (1) is electrically connected to the HF power source (101) and is configured to be connected to a consumer (102), in particular a plasma processing device, for example in the form of a plasma processing chamber, in a plasma processing supply system (108).

8. 10. The plasma process delivery system (108) of claim 7; a consumer (102), in particular a plasma processing device, for example in the form of a plasma processing chamber; A plasma processing system (100) comprising: The consumer (102) is connected to the plasma process supply system (6), The plasma processing system (100) is configured to supply power of an HF power signal to the consumer (102).

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