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CN-115398595-B - Impedance matching circuit and plasma supply system and method for operation

CN115398595BCN 115398595 BCN115398595 BCN 115398595BCN-115398595-B

Abstract

An impedance matching circuit (11), a plasma supply system (1) having such an impedance matching circuit and a method for operating such an impedance matching circuit, in particular in such a plasma supply system having a series circuit (10) attached to a high frequency connection (RFin), wherein the series circuit comprises at least one reactance, in particular a capacitance (C1, C2), and at least one switching element (T1, T2) having a steering input (G) to which a steering circuit (12) is attached, characterized in that the steering circuit is attached to an enable signal input by means of a coupler (13). In this way, a small switching time can be achieved with low losses in the switching element or elements.

Inventors

  • B. Nordmann

Assignees

  • 通快许廷格两合公司
  • 通快许廷格两合公司

Dates

Publication Date
20260421
Application Date
20210412
Priority Date
20200415

Claims (20)

  1. 1. Impedance matching circuit (11) with a series circuit (10) attached to a high-frequency connection (RFin), wherein the series circuit (10) comprises at least one reactance and at least one switching element (T1, T2) with a steering input (G) to which a steering circuit (12) is attached, characterized in that the steering circuit (12) is attached to an enable signal input (enable) via a coupler (13), the coupler (13) being designed for bridging a high voltage, which is greater than the HF voltage present in the impedance matching circuit (11) and/or the HF voltage present at the at least one switching element (T1, T2) with respect to ground, the steering circuit (12) being attached to the connection point of the series circuit (10) via a reference circuit (17), the reference circuit (17) having an internal DC voltage source, wherein the internal DC voltage source (V1, V2) has one capacitor (C3, C4) each.
  2. 2. Impedance matching circuit according to claim 1, characterized in that the coupler (13) is configured as an optical coupler, a magnetic coupler, an electromagnetic coupler or an electrical coupler.
  3. 3. Impedance matching circuit according to claim 2, characterized in that the coupler (13) is designed to decouple high frequencies, which correspond to the high frequencies at which the impedance matching circuit is loaded on the high frequency connection (RFin) during operation.
  4. 4. An impedance matching circuit as claimed in claim 3, characterized in that the impedance matching circuit is designed to switch on and off a switching element (T1, T2) or switching elements during operation, i.e. in the case of a voltage applied to the high-frequency connection (RFin).
  5. 5. An impedance matching circuit according to any of the preceding claims 1-3, characterized in that the steering circuit (12) is integrated into the coupler (13).
  6. 6. Impedance matching circuit according to claim 5, characterized in that the coupler (13) is built up from discrete structural elements.
  7. 7. Impedance matching circuit according to claim 5, characterized in that the coupler (13) is constructed as an integrated circuit.
  8. 8. Impedance matching circuit according to claim 5, characterized in that the steering circuit (12) is built up from discrete structural elements.
  9. 9. Impedance matching circuit according to claim 5, characterized in that the steering circuit (12) is constructed as an integrated circuit.
  10. 10. Impedance matching circuit according to claim 5, characterized in that the series circuit (10) has two transistors connected in anti-parallel, said transistors being connected at their source terminals (S) and being at a common source potential.
  11. 11. Impedance matching circuit according to claim 5, characterized in that the steering circuit (12) is attached to the supply voltage (Vbias) via at least one choke (L3, L4).
  12. 12. Impedance matching circuit according to claim 10, characterized in that the steering circuit (12) is attached to the source potential.
  13. 13. Impedance matching circuit according to claim 5, characterized in that the steering circuit (12) is attached to the junction point of the series circuit (10) by a reference circuit (17).
  14. 14. Impedance matching circuit according to claim 13, characterized in that the junction point is directly connected to the reference circuit (17).
  15. 15. Impedance matching circuit according to claim 14, characterized in that the reference circuit (17) has a voltage divider (R3, R4).
  16. 16. Impedance matching circuit, characterized in that it has a series circuit (10) attached to a high frequency connection (RFin), wherein the series circuit (10) comprises at least one reactance and at least one switching element (T1, T2) with a steering input (G) to which a steering circuit (12) is attached, characterized in that the steering circuit (12) is attached to an enable signal input (enable) by means of a coupler (13), the steering circuit (12) is attached to a connection point of the series circuit (10) by means of a reference circuit (17), the reference circuit (17) having an internal DC voltage source, wherein the internal DC voltage sources (V1, V2) have one capacitor (C3, C4) each.
  17. 17. Impedance matching circuit according to claim 16, characterized in that two internal DC voltage sources (V1, V2) are connected in series.
  18. 18. Impedance matching circuit according to claim 17, characterized in that the series circuit (10) has two transistors connected in anti-parallel, the transistors being connected at their source potential (S) and being located at a common source potential, a common connection point of two internal DC voltage sources (V1, V2) connected in series being connected with the source potential (S).
  19. 19. Impedance matching circuit according to the previous claim 17, characterized in that the reference circuit (17) is attached to the supply voltage (Vbias) through at least one choke (L3, L4).
  20. 20. Impedance matching circuit according to any of the preceding claims 16-19, characterized in that the series circuit (10) has a switching transistor with a source potential at ground.

Description

Impedance matching circuit and plasma supply system and method for operation Technical Field The invention relates to an impedance matching circuit with a series circuit attached to a high-frequency connection (HF connection), wherein the series circuit comprises at least one reactance, in particular a capacitance, and at least one switching element having a control input to which the control circuit is attached. The invention also includes a plasma supply system having such an impedance matching circuit. The invention also includes a method for operating the aforementioned impedance matching circuit, particularly in the aforementioned plasma supply system. Background High Frequency (HF) is referred to herein as a frequency of 1MHz or greater. Particularly a frequency of 10MHz or more. The reactance may be an inductance or a capacitance or a combination of both. Such impedance matching circuits are typically used in HF-excited plasma processes. HF-excited plasma processes are used, for example, for coating (sputtering) and/or etching substrates in the production of architectural glass, semiconductors, photovoltaic elements, flat screens, displays and the like. The impedance in such a process typically changes very rapidly, and therefore impedance matching should typically be matched very rapidly (in a few ms or less). The power of such a process is hundreds of W (e.g., 300W and above), but is also not as low as a few kW or tens of kW. In the case of such power, the voltage in the impedance matching circuit is typically several hundred V (e.g., 300V and above), and is not depleted by 1000V and above. The current in such a circuit may be several amperes, typically several tens of a, and may be 100A or more. Implementing an impedance matching circuit with such voltages and currents has been a great challenge. The rapid variability of reactance in such impedance matching circuits is an additional, very high challenge. Such an impedance matching circuit is shown, for example, in DE 10 2015 220 847 A1 and is referred to herein as an impedance matching network. The reactance 18, 20, 22 shown there can be set in a variable manner in order to be able to set the impedance matching. One possibility for variable tuning consists in switching in and out the reactance of different values by means of electronically controlled semiconductor switches. Reference is made to the disclosure of DE 10 2015 220 847 A1 and made the subject matter of the present disclosure. In such an impedance matching circuit, there is a requirement that the reactance, in particular the capacitance, in the connected impedance matching circuit is dynamically switched into the HF path. This should be achieved as quickly as possible. However, during switching, increased losses occur in the switching element, which may lead to thermal overload and damage of the switching element. Short switching times must be achieved in order to minimize the risk of wear and damage. Disclosure of Invention The object of the invention is to develop the impedance matching circuit mentioned in the opening paragraph such that the above-mentioned problems are reduced when switching in reactance, in particular capacitance. According to the invention, this object is achieved by an impedance matching circuit having a series circuit attached to a high-frequency terminal, wherein the series circuit comprises at least one reactance, in particular a capacitance, and at least one switching element having a control input to which a control circuit is attached, wherein the control circuit is attached to an enable signal input via a coupler. In this way, a small switching time can be achieved with low losses in the switching element or elements. The control circuit is preferably designed to be able to control the control input of the at least one switching element in such a way that the state of the at least one switching element, in particular the switching element, can be changed, in particular switched on and off. The coupler is used for transmitting an electrical signal or signal information between two separate electrical potentials, in particular between two electrical potentials separated by electroplating (galvanisch). I.e. there may be different potentials at the input and the output of the coupler. The coupler is used in particular for transmitting switching information to the control circuit. The enable signal input in the sense of the invention is a signal input by means of which the state of at least one switching element can be changed, in particular the switching element can be switched on and off. The coupler may be configured, for example, as an optical coupler, a magnetic coupler, an electromagnetic coupler, or an electrical coupler. The magnetic coupler is also called an inductive coupler. The coupling is achieved by a changing magnetic field. For example, a transformer or transformer may be constructed with or without ferrite as the induction enhancing element. Th