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

Abstract

The present invention relates to an impedance matching circuit (11), an impedance matching module (1) for a plasma process supply system (8) and a plasma process system (9), configured for a power of 500 W or more and a frequency in the range of 2 MHz to 100 MHz, for mounting on a cooling body (7), the impedance matching module comprising: a) a planar inductor (2); b) an insulating circuit board (3); c) a substrate (4), in particular a ceramic plate; d) the planar inductor (2) is divided into two planar conductor paths (2a, 2b) of equal length, connected in parallel and arranged on both sides and congruently on the insulating circuit board (3); e) the two conductor paths (2a, 2b) are two f) the substrate (4) is thicker than the insulating circuit board (3) and is fixedly connected to the surface of the insulating circuit board (3) over most of the lower surface (3b) of the insulating circuit board (3); g) the planar conductor paths (2a, 2b) can be spaced from the cooling body (7) by the substrate (4) to electrically insulate them from the cooling body (7); and h) the substrate (4) and the connection of the circuit board (3) to the substrate (4) are suitable for dissipating heat from the planar conductor paths to the cooling body (7).

Description

[Technical Field]

[0001] The present invention relates to an impedance matching circuit, a plasma process supply system, and an impedance matching module for a plasma processing system, in particular for mounting on a metallic cooling body, configured for powers of 500 W or more and frequencies in the range of 2 MHz to 100 MHz, and relates to an impedance matching circuit, a plasma process supply system, and a plasma processing system. [Background technology]

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

[0003] In such systems, the impedance of the load should be matched to the impedance of the power source, otherwise power reflections may occur, which directly affect the efficiency of the system and reduce its effectiveness.

[0004] An exemplary system in which an impedance matching circuit may be used may be 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. Without a connected plasma processing device, the plasma processing system may be referred to as a plasma process delivery system.

[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 a gas laser.

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

[0008] For this purpose, the plasma processing device may comprise an electrode fed with a high frequency power signal, hereinafter referred to as HF power signal, for generating the plasma.

[0009] Typically, a high power and especially a high voltage power supply is required, so that the plasma processing device can be connected to a high frequency power supply, hereinafter referred to as HF power supply.

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

[0011] Therefore, an impedance matching circuit is usually required to transform the impedance of the load to the nominal impedance of the HF power source. Such an impedance matching circuit is usually located between the HF power source and the plasma processing device, and is usually located 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] The greater the power to be transmitted, the more difficult it is to construct a compact impedance matching circuit. Therefore, the larger the power to be transmitted, the larger the impedance matching circuit becomes. This size makes its use space-consuming and allows little variability in its configuration in many devices. A compact configuration that saves as much space as possible is highly desirable.

[0014] German Utility Model No. 202016008958 (DE202016008958U1) discloses a solution for reducing the installation space and simplifying the production of a power combiner, which uses a planar structure.

[0015] In planar structures, the skin effect occurs in inductors and conductor tracks, resulting in undesirable hot spots that reduce the efficiency of the impedance matching circuit.

[0016] In addition, the quality of the inductors and conductor tracks used in the impedance matching circuit should generally be maximized, as this contributes to the efficiency, and thereby the quality, of the impedance matching circuit. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] German Utility Model Registration No. 202016008958 (DE202016008958U1) Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention is therefore based on the object of providing an impedance matching module for a power of more than 500 W and for frequencies in the range of 2 MHz to 100 MHz, which can be realized in a planar structure in the smallest possible space, avoids hot spots and has high-quality inductance and conductor paths. [Means for solving the problem]

[0019] This object is achieved by an impedance matching module according to independent claim 1. Advantageous further developments of the invention arise from the dependent claims and / or from the description.

[0020] According to the present invention, there is provided an impedance matching circuit, a plasma process supply system and an impedance matching module for a plasma process system, in particular for mounting on a metallic cooling body, configured for powers of 500 W or more and frequencies in the range of 2 MHz to 100 MHz, comprising: a) a planar inductor; b) an insulating circuit board; c) a substrate, in particular a ceramic plate; Equipped with d) the planar inductor is divided into two planar conductor tracks of equal length, electrically connected in parallel and disposed on opposite sides and congruently on an insulating circuit board; e) the two conductor paths are electrically connected via terminals and / or vias at the ends of the two conductor paths, in particular only at the ends of the two conductor paths; f) the substrate is thicker than the insulating circuit board and is fixedly connected to the surface of the insulating circuit board over most of the lower surface of the circuit board; g) the planar conductor tracks can be separated from the heat sink, in particular a metallic heat sink, by a substrate in order to electrically insulate the heat sink from the heat sink, h) the substrate and the connection of the circuit board to the substrate are configured to dissipate heat from the planar conductor tracks to a cooling body; An impedance matching module is proposed.

[0021] By doubling the conductor paths on the bottom and top surfaces of an insulating circuit board, the current in a planar inductor or conductor path is split into two paths. Due to the substantially identical current flow geometry with twice the conductor cross-section, losses are lower for equivalent inductance. This results in higher-quality inductance. By splitting the current between two conductor paths, localized heat spots, also known as hot spots, are avoided. "Substantially identical current flow geometry" refers to a geometry that exhibits identical geometric dimensions under typical manufacturing boundary conditions, particularly under typical circuit board manufacturing boundary conditions. Minor modifications to account for additional boundary conditions, such as fastening devices, contacts, and safety distances, may also fall within the term "substantially."

[0022] The conductor paths forming the inductors are made of an electrically conductive material, particularly copper. When selecting a material for the insulating circuit board, it is preferable to ensure that the material is suitable for high-frequency applications. Therefore, typical circuit board materials, such as FR-4 or polytetrafluoroethylene-based materials, are primarily suitable for insulating circuit boards. Polytetrafluoroethylene-based materials, also known as PTFE materials, are particularly suitable due to their low dielectric constant and low loss. For example, aluminum oxide ceramics or aluminum nitride ceramics can be used for the substrate.

[0023] The name FR-4 refers to a class of flame-retardant and flame-resistant composite materials made from epoxy resin and woven glass fiber. The abbreviation FR stands for "flame-retardant."

[0024] Polytetrafluoroethylene-based materials, also known as PTFE materials, are many times more expensive than FR-4, but they have particularly low losses in the HF range, allowing them to be used in HF circuit boards. This material has a lower dielectric constant and a higher dielectric strength in high electric fields, allowing the circuit boards to be constructed thinner.

[0025] "Fixed connection" means a connection between the circuit board and the substrate that cannot slide or loosen during operation and in which no air pockets exist or form. Such air pockets often occur in components connected with thermal paste. These have the disadvantage that high electric fields can occur at the edges of the air inclusions, which can lead to harmful partial discharges. In addition, thermal conductivity is adversely affected. A "fixed connection" is advantageously one that is produced by pressure and / or adhesive bonding, especially under pressure combined with heat.

[0026] By "majority" we mean a proportion of the area that occupies at least 60%, particularly at least 80%, of the total area. For example, if the bottom surface of the circuit board is 100 cm², 2 In this case, "the majority of the lower surface" means at least 60 cm2 , especially at least 80 cm 2 It should be.

[0027] This provides an impedance matching module that is compact due to its planar configuration, avoids the formation of local hot spots, and has high quality inductance and conductor tracks.

[0028] Two conductors can only be connected to each other at their ends, at terminals and vias. As a result, the current flow is forced to stay within the conductor, especially in the non-linear parts, and cannot escape to other parts. This reduces the skin effect, improving the quality of the inductance.

[0029] Furthermore, the substrates of the insulating circuit board and the impedance matching module can be bonded by applying heat and pressure to a prepreg inserted between them. "Prepreg" is a generic material name and an abbreviation for preimpregnated. It usually refers to a preimpregnated, nearly planar, flat textile semi-finished product, such as a woven fabric or scrim, with a thermoplastic or thermosetting matrix with unidirectional layers of yarn, often arranged at right angles.

[0030] Prepregs are cured under temperature and pressure to produce components. For example, they are prefabricated in the form of a web wound on a roll. The term prepreg includes not only unidirectionally reinforced or flat semi-finished products, but also other preforms of essentially any shape, which, in the broadest sense, consist of an uncured thermosetting matrix filled with fibers. The matrix is ​​in a partially crosslinked state and is paste-like to solid, but can be reliquefied by heating.

[0031] Prepregs are machinable and therefore often used in automated processes. They produce consistently high quality. Advantages include low waviness and a high fiber volume content. Curing at high temperatures allows for short cycle times for further processing. Processing requires high investment costs, such as autoclaves, installation robots, and refrigerated storage. Such prepregs are commonly used to bond multiple circuit boards together to form multilayer circuit boards. To ensure a secure and long-lasting bond, the materials being bonded together should have very similar properties regarding their expansion when heated. However, this is not always true for the circuit board and the substrate, especially when the substrate is made of ceramic. This is the first argument against such a connection. However, ceramics have very good thermal conductivity, as well as very good electrical insulation properties and low dielectric loss when insulating high-voltage, high-frequency signals. Contrary to expectations, tests have shown that reliable and long-lasting bonding of materials with different properties, such as ceramics with FR-4 and / or ceramics containing PTFE materials, is possible, even at small dimensions. The small dimension in the above context is 400 cm 2 "bonded area" means a bonded area of ​​less than 20 cm and / or a bonded area having a maximum length of 20 cm.

[0032] The entire impedance matching module can be applied via the substrate to a cooling body that dissipates heat from the planar conductor tracks. Such a cooling body can preferably be made of metal, in particular aluminum and / or copper. The cooling body can also be a fluid cooling body having at least one channel through which a fluid flows, and heat is dissipated via the cooling channel. Thermal paste can be applied between the cooling body and the substrate, and the impedance matching module can be attached to the cooling body using a bracket.

[0033] Additionally, the impedance matching module can be used in an impedance matching circuit within a plasma process delivery system or a plasma processing system.

[0034] Such a plasma process supply system may include an HF power source in addition to an impedance matching circuit.

[0035] In addition to the impedance matching module, such an impedance matching circuit may also include additional reactances, such as inductors and / or capacitors, semiconductor switching elements, and control circuits. The reactances can be connected and disconnected via the semiconductor switching elements to change the impedance from the input to the output of the impedance matching circuit. The semiconductor switching elements can be, for example, MOSFETs (metal-oxide-semiconductor field-effect transistors). The connection and disconnection using the semiconductor switching elements can be controlled via the control circuit. A control circuit 16 can be configured for this purpose.

[0036] The entire impedance matching circuit can be configured to be connected to an HF power source on the one hand and to a plasma processing device on the other hand.

[0037] In a plasma processing system, such a plasma processing device may be present and connected to an impedance matching circuit, and the plasma processing device may be supplied with power provided by an HF power source through the impedance matching circuit. [Brief explanation of the drawings]

[0038] Preferred exemplary embodiments of the invention are shown diagrammatically in the drawings and are explained in more detail below with reference to the figures in which: [Figure 1] 1 is a schematic cross-sectional view of a first embodiment of an impedance matching module according to the present invention arranged on a cooling body; [Figure 2]1 is a plan view of an embodiment of the top surface of an isolation circuit board of an impedance matching module according to the present invention. [Figure 3] 2 is a schematic diagram of an embodiment of the underside of an insulating circuit board of an impedance matching module according to the present invention. [Figure 4] 1 is a schematic diagram of an embodiment of a plasma processing system. [Figure 5] FIG. 2 is a perspective view of an impedance matching module. DETAILED DESCRIPTION OF THE INVENTION

[0039] FIG. 1 shows a first embodiment of an impedance matching module 1 according to the present invention, which is arranged on a cooling body 7. The insulating circuit board 3 and the substrate 4 of the impedance matching module 1 are also visible in the cross section shown. The insulating circuit board 3 is arranged on and connected to the substrate 4. The substrate 4 is arranged on and connected to the cooling body 7. Due to the thickness of the substrate, the insulating circuit board 3 is spaced apart from and electrically insulated from the cooling body 7. The inductor 2 is arranged as a planar conductor trace 2a on the upper surface 3a of the insulating circuit board 3 and as a planar conductor trace 2b on the lower surface 3b. The cooling body 7 is shown as a fluid cooling body having a plurality of cooling channels 7a through which a fluid, e.g., water, can flow, dissipating the generated heat.

[0040] FIG. 2 shows an embodiment of the top surface 3a of the insulating circuit board 3 of the impedance matching module 1. This top surface 3a of the insulating circuit board 3 has a planar conductor track 2a, terminals 5a, 5b, 5c, 5d, and 5e, and vias 6a, 6b, 6c, and 6d. The planar inductor 2 has two planar conductor tracks 2a and 2b, of which only one, 2a, is visible on the top surface 3a. The other, 2b, is disposed substantially congruently on the bottom surface 3b, as shown in FIG. 3. The two planar conductor tracks 2a and 2b have asymmetric shapes, and in particular, the two conductor tracks 2a and 2b have meandering paths. The planar inductor 2 having the two planar conductor tracks 2a and 2b has a straight portion 20 followed by a non-linear portion 21, which here has a particularly strongly curved shape, whereby the planar conductor tracks 2a and 2b reverse their directions. These cross-sectional changes occur several times in succession with the curve shape being alternating right and left curves, so that the planar inductor 2 can utilize the area of ​​the insulating circuit board 3 and have the desired characteristics.

[0041] Additionally, terminals 5a, 5b, 5c, 5d, and 5e are disposed on the upper surface 3a of the insulating circuit board 3 and are connected to the planar inductor 2. Via these terminals, the impedance matching module 1 can be integrated into an impedance matching circuit 11. Vias 6a, 6b, 6c, and 6d, which have round shapes, serve to electrically connect the planar inductor 2 on the upper surface 3a of the insulating circuit board 3 with the planar inductor on the lower surface 3b. For example, terminals for HF power signals can also be applied to the vias 6a, 6b, 6c, and 6d on the upper surface 3a of the insulating circuit board 3.

[0042] 3 shows an embodiment of the bottom surface 3b of the insulating circuit board 3 of the impedance matching module 1. The bottom surface 3b represents the reverse side of the top surface 3a shown in FIG. 2 and therefore has equivalent components. Therefore, a description of the components can be taken from the description of FIG. 2. The basic difference between the top and bottom surfaces of the insulating circuit board 3 is that, in the top view, the planar conductor tracks 2b on the bottom surface 3b are arranged in a mirror-image manner with respect to the planar conductor tracks 2a on the top surface 3a. This means that the two planar conductor tracks 2a, 2b are arranged exactly one above the other, i.e., are congruent, but are electrically separated by the circuit board 3.

[0043] The terminals 5a, 5b, 5c, 5d, 5e may each form the end of a conductor path 2a, 2b, which offer the possibility to adjust the desired inductance or match it to frequency by connecting the following components of the impedance matching circuit 11 to one of the corresponding terminals 5a, 5b, 5c, 5d, 5e:

[0044] Vias 6a, 6b, 6c, 6d may each form the end of a conductor path 2a, 2b, which serve to balance the desired inductance or match it to frequency by connecting additional components of an impedance matching circuit 11 to one of the corresponding vias 6a, 6b, 6c, 6d.

[0045] The two conductor paths 2a and 2b are interconnected only at the terminals 5a, 5b, 5c, 5d, and 5e and the vias 6a, 6b, 6c, and 6d. As a result, the current flowing in the non-linear portion 21 in particular is forced to remain in the conductor paths 2a and 2b and cannot escape to the other side. This reduces the skin effect and therefore improves the quality of the inductance.

[0046] In Figures 2 and 3, possible substrate 4 positions are also shown as dashed boundaries.

[0047] Figure 5 shows a perspective view of the impedance matching module 1. Here, the same reference numerals as in Figures 1, 2 and 3 are used.

[0048] 4 shows an embodiment of an exemplary plasma processing system 9. The plasma processing system 9 includes a plasma process supply system 8 and a plasma processing apparatus 10. The plasma process supply system 8 includes an impedance matching circuit 11 and an HF power supply 12. The impedance matching module 1 according to the present invention is incorporated into the impedance matching circuit 11. In addition, the impedance matching circuit 11 includes an additional reactance 14, such as a capacitor and / or a coil, a semiconductor switching element 15, and a control circuit 16.

[0049] Such an exemplary plasma processing system 11 is described, for example, in German Patent Application No. DE102023104942.9, entitled "Impedance matching circuit, plasma process supply system and plasma process system," filed on February 28, 2023, which is incorporated herein by reference in its entirety. In particular, the additional impedance matching circuit (1) described therein allows the present impedance matching circuit 11 to be further developed using individual or all features of the additional impedance matching circuit (1).

[0050] Such an exemplary plasma processing system 9 is described, for example, in German Patent Application No. DE102023104955.0, filed February 28, 2023, entitled "Impedance matching circuit for a plasma process system and a plasma process system with such an impedance matching circuit," which is incorporated herein by reference in its entirety. In particular, at least one of the coils (15, 18, 19, 24, 25) described therein can be configured with the features of the impedance matching module 1 described herein.

[0051] Such an exemplary plasma processing system 9 is described, for example, in German Patent Application No. DE102023104948.8, entitled "Impedance matching circuit, plasma process supply system and plasma process system," filed February 28, 2023, which is incorporated herein by reference in its entirety. In particular, at least one of the inductors (L2a, L2b, L3a, L3d, L3e, L3f) described therein can be configured with the features of the impedance matching module 1 described herein.

[0052] Due to the features described above, the number of components such as semiconductor switching elements or reactances, coils and / or capacitors, and capacitors and / or inductances can be kept smaller, thereby achieving a more compact configuration.

Claims

1. An impedance matching circuit (11), an impedance matching module (1) for a plasma process supply system (8) and a plasma process system (9), in particular for mounting on a metallic cooling body (7), for a power of 500 W or more and a frequency in the range of 2 MHz to 100 MHz, comprising: a) a planar inductor (2); b) an insulating circuit board (3); c) a substrate (4), in particular a ceramic plate; Equipped with d) the planar inductor (2) is divided into two planar conductor tracks (2a, 2b) of equal length, electrically connected in parallel and arranged congruently on both sides of the insulating circuit board (3); e) the two conductor paths (2a, 2b) are electrically connected via terminals (5a, 5b, 5c, 5d, 5e) and / or vias (6a, 6b, 6c, 6d) at the ends of the two conductor paths (2a, 2b); f) the substrate (4) is thicker than the insulating circuit board (3) and is fixedly connected to the surface of the insulating circuit board (3) over most of the lower surface (3b) of the insulating circuit board (3); g) the planar conductor tracks (2a, 2b) can be spaced from the cooling body (7) by the substrate (4) in order to electrically insulate them from the cooling body (7); h) the substrate (4) and the connection of the circuit board (3) to the substrate (4) are suitable for dissipating heat from the planar conductor tracks to the cooling body (7); Impedance matching module (1).

2. 2. The impedance matching module (1) according to claim 1, wherein the substrate (4) is connected to the insulating circuit board (3) by applying heat and pressure via a prepreg (13) inserted between the substrate and the insulating circuit board (3).

3. 3. The impedance matching module (1) according to claim 1 or 2, wherein the impedance matching module (1) is connected via the substrate (4) to a cooling body (7), in particular a metallic cooling body.

4. 4. The impedance matching module (1) of claim 3, wherein the cooling body (7) is a fluid cooling body having at least one cooling channel (7a), through which a fluid flows and through which the heat can be dissipated.

5. 5. The impedance matching module (1) according to any one of claims 1 to 4, wherein the fixed connection of the insulating circuit board (3) to the substrate (4) is produced by pressure and / or adhesive bonding, in particular under pressure combined with heat.

6. 6. An impedance matching module (1) according to any one of claims 1 to 5, wherein the two conductor paths (2a, 2b) are connected to each other only at the ends of the two conductor paths (2a, 2b), at the terminals and the vias.

7. 7. The impedance matching module (1) according to any one of the preceding claims, wherein the two conductor tracks (2a, 2b) have a serpentine path.

8. 8. An impedance matching module (1) according to any one of claims 1 to 7, wherein the two conductor paths (2a, 2b) have a plurality of terminals (5a, 5b, 5c, 5d, 5e) along the path of the two conductor paths (2a, 2b), each of the terminals having the possibility of connecting additional components, whereby each can form an end of the conductor path (2a, 2b).

9. 9. An impedance matching module (1) according to any one of claims 1 to 8, wherein the two conductor paths (2a, 2b) have a plurality of vias (6a, 6b, 6c, 6d) along the path of the two conductor paths (2a, 2b), each of which has the possibility of connecting additional components, whereby each of which may form an end of the conductor path (2a, 2b).

10. a) an impedance matching module (1) according to any one of claims 1 to 9; b) additional reactances, e.g., capacitors and / or inductors; c) a semiconductor switching element (15), in particular a transistor or a PIN diode; d) a control circuit (16); An impedance matching circuit (11) comprising: e) the semiconductor switching element (15) is configured to connect and disconnect the reactance to vary the impedance from the input to the output of the impedance matching circuit (11); f) the control circuit (16) is configured to be able to control the connection and disconnection of the reactance by the semiconductor switching element (15); An impedance matching circuit (11).

11. 11. The impedance matching circuit (11) of claim 10, configured to be connected on the one hand to an HF power source (12) and on the other hand to a plasma processing device (10).

12. an HF power source (12) for providing an HF power signal; An impedance matching circuit (11) according to claim 10 or 11; A plasma process delivery system (8) comprising: The impedance matching circuit (11) is electrically connected to the HF power source (12) and is configured to be connected to a plasma processing device (10). A plasma process delivery system (8).

13. A plasma process delivery system (8) according to claim 12; A plasma processing device (10); A plasma processing system (9) comprising: The plasma processing device (10) is connected to the plasma processing supply system (8); The plasma process supply system (8) is configured to supply power of an HF power signal to the plasma process device (10). Plasma processing system (9).

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