Connection assembly, plasma process flow supply system, plasma process system, and method for operating a plasma process

Abstract

The invention relates to a connection assembly (1) for limiting the quality and maintaining the bandwidth for a plasma process flow supply system (10), having: a) a first inner conductor (2) which is designed to provide a first direct voltage by means of a first DC power supply (5), b) a second inner conductor (4) which is designed to provide a second direct voltage by means of a second DC power supply (8), and c) an outer conductor (9) which surrounds the two inner conductors (2, 4) in order to shield same and displays the reference potential of the two inner conductors (2, 4), wherein d) the connection assembly (1) is designed to be connected to: i. a plasma process assembly (6), the DC power supplies (5, 8), and an HF power supply (9) or ii. an impedance adaptation circuit (7) and a plasma process assembly (6) and / or iii. an impedance adaptation circuit (7), the DC power supplies (5, 8), and an HF power supply (9); and e) the connection assembly (1) is designed to guide an HF power signal related to the outer conductor (9) via the two inner conductors (2, 4) in order to supply the plasma process assembly (6) with HF power by means of the HF power supply (3).

Description

[0001] Connection arrangement, plasma process power supply system, plasma process system and a method for operating a plasma process

[0002] The present invention relates to a connection arrangement for a plasma process power supply system, a plasma process power supply system, a plasma process system and a method for operating a plasma process.

[0003] Such a plasma process power supply system can, for example, be part of a plasma process system in which a plasma process arrangement is supplied with electrical power by means of several power supplies.

[0004] Such a plasma processing arrangement can, for example, be a plasma processing chamber that is used for industrial plasma processes such as the surface treatment of workpieces, semiconductor manufacturing with plasma or the processing of workpieces with gas lasers.

[0005] In such an application, the plasma process arrangement serves to generate plasma.

[0006] For this purpose, a plasma processing arrangement can have two electrodes that are fed with two DC voltages, e.g., for supplying electrostatic chucks, and a high-frequency power signal for generating the plasma, hereinafter referred to as the RF power signal.

[0007] Typically, the plasma process arrangement is connected to several DC power supplies and a high-frequency power supply, hereinafter referred to as RF power supply.

[0008] The plasma process occurring in the plasma processing system has the problem that the electrical load impedance of the plasma processing system, which occurs during the process, depends on the conditions within the plasma processing system and can vary greatly. In particular, the properties of the workpiece, electrodes, and gas conditions are important.

[0009] For this reason, an impedance matching circuit is usually required to transform the load impedance to a nominal impedance of the RF power supply. Such an impedance matching circuit is typically placed between the RF power supply and the plasma processing device, usually in the immediate vicinity of the plasma processing device. In addition to the impedance matching circuits, plasma processing power supply systems may incorporate one or more filters in one or more so-called filter boxes. Such a filter box contains electrical circuits that serve to protect against unwanted, particularly reverse, currents with a frequency different from the desired frequency.

[0010] Such a filter box can be a circuit arrangement arranged in a housing, which has several inputs for the connection of several power supplies with, for example, different operating frequencies, one or more outputs and one or more filter circuits.

[0011] For example, DC, AC and / or RF power supplies can be connected to the inputs.

[0012] The filter circuits ensure that connected power supplies do not interfere with each other by protecting them from unwanted currents of a different frequency relative to the input.

[0013] For this purpose, the filter circuits preferably have inductances and / or capacitances, which are often very expensive for the application in question due to the required current and voltage load capacity as well as the need for cooling.

[0014] The filter boxes can be arranged between the impedance matching circuit and the plasma process arrangement.

[0015] All of these components, such as DC power supplies, RF power supplies, and filter boxes, but especially the impedance matching circuit and the plasma processing arrangement, must be interconnected in a plasma processing power supply system. When powered by three different signals, such a connection in conventional arrangements requires considerable design effort, since a separate line is used for each signal.

[0016] In addition to the structural effort required for such a connection arrangement, this also results in costs for three connecting lines.

[0017] The present invention is therefore based on the object of

[0018] To provide a connection arrangement for a plasma process power supply system that simplifies the design of a plasma process power supply system.

[0019] This problem is solved by a connecting arrangement according to independent claim 1. Advantageous developments of the invention emerge from the subclaims and / or the description.

[0020] According to the present invention, a connection arrangement for a plasma process power supply system is therefore proposed, comprising: a) a first inner conductor designed to provide a first direct voltage by a first DC power supply, b) a second inner conductor designed to provide a second direct voltage by a second DC power supply, c) an outer conductor which surrounds the two inner conductors in a shielding manner and represents the reference potential of the two inner conductors, d) wherein the connection arrangement is designed for connection to: i. a plasma process arrangement and to two DC power supplies and to an RF power supply or ii. to an impedance matching circuit and a plasma process arrangement and / or iii.to an impedance matching circuit and to two DC power supplies and an RF power supply; e) wherein the connection arrangement is designed to conduct an RF power signal related to the outer conductor via the two inner conductors for supplying the plasma process arrangement with RF power by the RF power supply.

[0021] The connection arrangement therefore combines the provision of two DC voltages and the transmission of an RF power signal in a single arrangement, thus simplifying the design of a plasma process power supply system. RF power signal refers to a power signal with power levels > 500 W, in particular > 1 kW, and particularly preferably > 3 kW. RF refers to high frequency. In the plasma process field, RF refers to frequencies > 2 MHz, but in this case, frequencies > 10 MHz and < 200 MHz are particularly important.

[0022] Such a plasma process power supply system typically comprises two DC power supplies, an RF power supply, and a connection arrangement for connecting a possible load.

[0023] A possible load could be, for example, a plasma processing device such as a plasma processing chamber with two electrodes. These electrodes typically require the supply of two DC signals and one RF signal, the former for use as electrostatic chucks, for example, and the latter for plasma generation, for example.

[0024] Optionally, additional components such as an impedance matching circuit or circuits or components can also be part of a plasma process power supply system as a protective measure. One or more inductors and / or capacitors can be used as a protective measure, in particular one or more DC blocking capacitors or RF blocking inductors. A DC blocking capacitor is a capacitor designed and arranged to prevent a DC current. An RF blocking inductor is an inductor designed and arranged to significantly reduce, in particular to prevent, an RF current. These components can thus protect against unwanted DC or RF reverse currents.

[0025] A DC power supply is a power supply designed to provide DC voltage and DC current. This power can be pulsed or bipolar pulsed.

[0026] The reference potential refers to a voltage potential that maintains a constant potential relative to ground over several periods of the RF signal. In particular, it is ground itself.

[0027] For use of the connection arrangement in a plasma process power supply system, the inner conductors of the connection arrangement can each be connected to a different DC power supply and, in addition, both inner conductors can be connected together to an RF power supply.

[0028] This allows a potential load, such as a plasma processing chamber, to be supplied with three different signals via a single, common arrangement, without the need for a complex design comprising multiple cables and connectors. The connection arrangement can be designed such that the RF power signal in such an arrangement can be coupled in common mode to both inner conductors via capacitive coupling. As a result, the connection arrangement for the RF power signal acts from the outside like a conventional coaxial cable, enabling, for example, the use of typical non-contact current and / or voltage sensors for alternating voltages, especially RF signals.

[0029] In one aspect, the connection arrangement is designed for a predeterminable RF impedance. This RF impedance can, in particular, be based on the impedance of the intended connection of the connection arrangement.

[0030] Thus, in the case of a connection to a plasma processing device, the impedance may be equal to the impedance of the plasma processing device and in the case of a connection to an impedance matching circuit, the impedance may be equal to the impedance of the impedance matching circuit.

[0031] For example, if the connection is a coaxial cable, the impedance is determined by the inner diameter of the outer conductor and the outer diameter of the inner conductor, as well as the dielectric. The inner conductors can, for example, have an approximately round outer diameter. The outer conductor's inner diameter is adjustable. This allows the cable's impedance to be set according to specifications.

[0032] Furthermore, the connection arrangement can be designed to include a dielectric. This dielectric can be arranged between the two inner conductors or between the inner conductors and the outer conductor. The material of the dielectric can vary between the two inner conductors and the inner conductors and the outer conductor. A solid material can be used between the inner conductors, for example, and can also serve as a support for the two inner conductors. Air, liquid, or a combination of both with a solid material can be used between the inner conductors and the outer conductor to insulate the different conductors from one another.

[0033] Such a solid dielectric can preferably comprise a material which, in terms of its properties such as relative permittivity and loss angle, is compatible with another material. For example, the materials used can be PTFE (polytetrafluoroethylene) or aluminum oxide. In addition, when both inner conductors are excited in common mode, the electric RF field is mainly formed between the inner and outer conductors. As a result, the material of the dielectric between the surfaces of the inner conductor has only a very small influence on the properties of the connection arrangement if the two inner conductors are only a short distance apart, are at the same RF potential, and differ essentially only in the DC potential. This can further enhance the effect that the connection arrangement acts like a conventional coaxial cable for the RF power signal.A small distance here means, for example, a distance of less than or equal to 3 mm, in particular less than or equal to 1 mm, particularly preferably less than or equal to 0.5 mm.

[0034] The connection arrangement can comprise a current sensor, a voltage sensor, or a combined current and voltage sensor, particularly for determining the transmitted RF voltage and RF current. This allows for monitoring of the RF power signal integrated into the arrangement.

[0035] Such a sensor can be arranged around the two inner conductors of the coaxial cable. This allows the RF voltage and / or RF current to be determined, even if it is distributed across both inner conductors.

[0036] The connection arrangement can include a sensor for detecting the forward and / or reverse power. Such a sensor can be configured, for example, as a so-called directional coupler. Such a directional coupler is described, for example, in US Pat. Nos. 7,755,451 B2 and 10,490,876 B2.

[0037] In a further embodiment of the connecting arrangement, the inner conductors can be configured as two conductor halves with a semicircular cross-section, separated from each other by a dielectric. This embodiment offers the advantage of a homogeneous electric field between the inner conductors and the outer conductor of the connecting arrangement. In one embodiment, the connecting arrangement has more than two inner conductors, each separated from each other by a dielectric and together forming a circular cross-section. This allows more than two DC voltages to be supplied to the plasma with low loss and a predeterminable impedance.

[0038] The connection arrangement can be used in a variety of places in systems such as plasma process power supply systems or plasma process systems.

[0039] Thus, an embodiment of a plasma process power supply system can comprise a connection arrangement in addition to a first DC power supply, a second DC power supply, an RF power supply, and a plurality of DC blocking capacitors and RF blocking inductors. In such a system, connections are made between the first DC power supply and the first inner conductor of the connection arrangement, the second DC power supply and the second inner conductor of the connection arrangement, and the RF power supply and the two inner conductors. An RF blocking inductor is arranged between each of the DC power supplies and the inner conductors of the connection arrangement. A DC blocking capacitor is arranged between each of the RF power supply and the inner conductors of the connection arrangement.

[0040] A load, such as a plasma processing device, which requires a supply of these three signals, can then be connected to the connection arrangement.

[0041] Such a plasma process supply system may further comprise an impedance matching circuit that can be connected to the connection arrangement. A possible load can then be connected to the impedance matching circuit using a connection arrangement.

[0042] Such an overall system, in which a load in the form of a plasma process arrangement is connected to the described plasma process power supply system, can then be referred to as a possible embodiment of a plasma process system. Furthermore, the connection arrangement can be used in a part of a plasma process system. Such a part of a plasma process system can have an impedance matching circuit, a plasma process arrangement, and the connection arrangement. The connection arrangement can establish the connection between the impedance matching circuit and the plasma process arrangement. Via the connection arrangement, the plasma process arrangement can be supplied with two DC voltages and an RF power signal, which can be provided by two DC power supplies and one RF power supply. For this purpose, the RF power supply can be connected to the connection arrangement via the impedance matching circuit.There are several options for feeding the two DC power supplies. One option is to connect the two DC power supplies to the interconnection assembly via the impedance matching circuit. The other option is to connect the DC power supplies to the interconnection assembly downstream of the impedance matching circuit. Feeding the power supplies via the impedance matching circuit allows the impedance matching circuit to be positioned closer to the plasma processing assembly, which can provide advantages in terms of bandwidth and impedance matching. Feeding the power supplies downstream of the impedance matching circuit has the advantage that protective measures such as DC blocking capacitors outside the impedance matching circuit can be omitted if the impedance matching circuit already includes them.

[0043] Furthermore, the connection arrangement can be used in a method for operating a plasma process in a plasma process arrangement, in particular according to a previously described plasma process arrangement. In this case, the connection arrangement can be part of a plasma process system, in particular of a previously described plasma process system. Such a method can comprise several steps. First, the plasma process arrangement can be supplied with two direct voltages and an RF power signal. For this purpose, a first direct voltage can be provided by a first DC power supply via a first inner conductor of the connection arrangement of the plasma process arrangement. Simultaneously, a second direct voltage can be provided by a second DC power supply via a second inner conductor of the connection arrangement of the plasma process arrangement.Simultaneously with these two provisions, an RF power signal can be transmitted from an RF power supply to the plasma processing arrangement via both inner conductors of the connection arrangement.

[0044] Following these steps, a plasma can be generated in the plasma process arrangement.

[0045] The schematic drawing shows embodiments of the invention in various stages of use and is explained in more detail in the following description.

[0046] They show:

[0047] Fig. 1 Connection arrangement arranged in a plasma process system.

[0048] Fig. 2a-d Several different plasma process power supply systems and

[0049] Plasma processing systems with a connection arrangement.

[0050] Fig. 3 Connection arrangement with sensor.

[0051] Detailed description of the drawings:

[0052] Fig. 1 shows a first embodiment of a connection arrangement 1 according to the invention for an exemplary plasma process power supply system 10 arranged in an exemplary plasma process system 12. The connection arrangement 1 has two inner conductors 2, 4 and an outer conductor 9 and is part of a plasma process power supply system 10. This plasma process power supply system 10 additionally has two DC power supplies 5, 8, an RF power supply 3 and an impedance matching circuit 7 and is part of a plasma process system 12. This plasma process system 12 additionally has a plasma process arrangement 6.

[0053] The connection arrangement 1 connects the impedance matching circuit 7 and the plasma process arrangement 6.

[0054] The inner conductors 2, 4 of the connection arrangement 1 are designed to provide two DC voltages and transmit an RF power signal. Each inner conductor 2, 4 can provide a different DC voltage, and the RF power signal can be coupled to both inner conductors 2, 4. These signals are referenced to the outer conductor 9 of the connection arrangement 1 and are provided by two DC power supplies 5, 8 and an RF power supply 3. The purpose of the signals is to feed two electrodes in the plasma processing arrangement 6. These electrodes can be used as electrostatic chucks by being fed with the DC power supplies, and plasma can be generated at the electrodes using the RF power signal.

[0055] The impedance matching circuit 7 serves the purpose of transforming the impedance of the plasma processing arrangement 6 to a nominal impedance of the RF power supply 3, since the impedance of the plasma processing arrangement 6 can vary greatly during plasma processes. Additionally, the impedance matching circuit 7 can contain further devices such as DC blocking capacitors C1, C2 or RF blocking inductors L1, L2 for filtering unwanted return currents.

[0056] Two DC power supplies 5, 8 and an RF power supply 3 are connected to the impedance matching circuit 7, which are also connected to the inner conductors 2, 4 of the connection arrangement 1 via the impedance matching circuit 7.

[0057] Fig. 2a shows a possibility of arranging an embodiment of the connection arrangement 1 according to the invention in a plasma process system.

[0058] The plasma process system comprises two DC power supplies 5, 8, an RF power supply 3, a plasma process arrangement 6 and the connection arrangement 1.

[0059] The connection arrangement 1 is arranged between the power supplies 3, 5, 8 and the plasma processing arrangement 6. The plasma processing arrangement 6 is supplied with two DC voltages and an RF power signal from the power supplies 3, 5, 8 via the connection arrangement 1.

[0060] RF blocking inductors L1, L2 are interposed to connect the DC power supplies 5, 8 and the connecting arrangement 1. DC blocking capacitors C1, C2 are interposed to connect the RF power supply 3 and the connecting arrangement 1. These components serve as a protective measure against unwanted reverse currents. Fig. 2b shows one possible way of arranging an embodiment of the connecting arrangement 1 according to the invention in part of an exemplary plasma processing system.

[0061] The part of the plasma processing system comprises an impedance matching circuit 7, a plasma processing arrangement 6 and the connection arrangement 1.

[0062] The connection arrangement 1 is arranged between the impedance matching circuit 7 and the plasma processing arrangement 6. Via the connection arrangement 1, the plasma processing arrangement 1 can be supplied with two DC voltages and an RF power signal, which can be provided by two DC power supplies 5, 8 and an RF power supply 3.

[0063] The RF power supply 3 can be connected to the impedance matching circuit 7.

[0064] The two DC voltages can be fed via the DC power supplies 5, 8 either before or after the impedance matching circuit 7. Feeding them before or after the impedance matching circuit 7 offers design advantages, as the impedance matching circuit 7 can be positioned closer to the plasma processing arrangement 6, which can also provide advantages in terms of impedance matching and bandwidth.

[0065] When feeding in after the impedance matching circuit 7, no protective measures such as DC blocking capacitors outside the impedance matching circuit 7 are necessary if the impedance matching circuit 7 already provides these.

[0066] Fig. 2c shows a possibility of arranging an embodiment of the connection arrangement 1 according to the invention in an exemplary plasma process power supply system.

[0067] The plasma process power supply system comprises an impedance matching circuit 7, two DC power supplies 5, 8, an RF power supply 3 and the connection arrangement 1.

[0068] The connection arrangement 1 is arranged between the power supplies 3, 5, and 8 and the impedance matching circuit 7. Two DC voltages and an RF power signal can be fed into the impedance matching circuit 7 via the connection arrangement 1. These signals are provided by the power supplies 3, 5, and 8. RF blocking inductors L1, L2 are interposed to connect the DC power supplies 5, 8 and the connection arrangement 1. DC blocking capacitors C1, C2 are interposed to connect the RF power supply 3 and the connection arrangement 1. These components serve as a protective measure against unwanted reverse currents.

[0069] A load, such as a plasma processing chamber, which requires two DC voltages and an RF power signal, can be connected to the impedance matching circuit.

[0070] Fig. 2d shows a further possibility of arranging an embodiment of the connection arrangement 1 according to the invention in an exemplary plasma process system.

[0071] The plasma processing system comprises a plasma processing arrangement 6, an impedance matching circuit 7, two DC power supplies 5, 8, an RF power supply 3 and the connection arrangement 1.

[0072] The connection arrangement 1 is arranged once between the plasma process arrangement 6 and the impedance matching circuit 7 and once between the impedance matching circuit 7 and the power supplies 3, 5, 8.

[0073] The plasma processing arrangement 6 is supplied with two DC voltages and an RF power signal via the connection arrangement 1. The signals are provided by the power supplies 3, 5, and 8.

[0074] RF blocking inductors L1 and L2 are used to connect DC power supplies 5 and 8 to the connection assembly 1. DC blocking capacitors C1 and C2 are used to connect the RF power supply 3 and the connection assembly 1. These components serve as a protective measure against unwanted reverse currents.

[0075] The impedance matching circuit 7 serves the purpose of transforming the load impedance of the plasma process arrangement 6 to a nominal impedance of the RF power arrangement 3.

[0076] Fig. 3 shows an embodiment of the inventive

[0077] Connection arrangement 1 with a combined sensor, in particular a current and voltage sensor 13. A current sensor in such an application is described, for example, in US Pat. No. 7,321,227 B2. This can be supplemented by an additional voltage sensor, e.g., a capacitive voltage sensor.

[0078] Such a combined current and voltage sensor 13 is described, for example, in US 2012 / 0223697 A1. In addition to the current and voltage sensor 13, Fig. 3 shows the two inner conductors 2, 4 and the outer conductor 9 of the connection arrangement 1.

[0079] The connection arrangement 1 can also have a sensor for determining the forward and / or reverse power. Such a sensor can be designed, for example, as a so-called directional coupler. Such a directional coupler is described, for example, in US Pat. Nos. 7,755,451 B2 and 10,490,876 B2.

[0080] In Fig. 3 the dielectric 11 between the inner conductors 2, 4 and between the inner conductors 2, 4 and the outer conductor 9 is also shown.

Claims

Patent claims 1. Connection arrangement (1) for a plasma process power supply system (10) comprising: a) a first inner conductor (2) designed to provide a first direct voltage by a first DC power supply (5), b) a second inner conductor (4) designed to provide a second direct voltage by a second DC power supply (8), c) an outer conductor (9) which surrounds the two inner conductors (2, 4) in a shielding manner and represents the reference potential of the two inner conductors (2, 4), d) wherein the connection arrangement (1) is designed for connection to: i. a plasma process arrangement (6) and to the DC power supplies (5, 8) and to an RF power supply (9) or ii. to an impedance matching circuit (7) and a plasma process arrangement (6) and / or iii.to an impedance matching circuit (7) and to the DC power supplies (5, 8) and an RF power supply (3); e) wherein the connection arrangement (1) is designed to conduct an RF power signal related to the outer conductor (9) via the two inner conductors (2, 4) for supplying the plasma process arrangement (6) with RF power by the RF power supply (3).

2. Connection arrangement (1) according to claim 1, wherein the connection arrangement (1) is designed such that the RF power signal can be coupled to both inner conductors (2, 4) via capacitive coupling in common mode.

3. Connecting arrangement (1) according to one of the preceding claims, wherein the connecting arrangement (1) comprises a dielectric (11) arranged between: i. the two inner conductors (2, 4) and ii. the inner conductors (2, 4) and the outer conductor (9).

4. Connection arrangement (1) according to claim 3, wherein the material of the dielectric (11) between the two inner conductors (2, 4) and the material of the dielectric (11) between the inner conductor and outer conductor (9) differ.

5. Connection arrangement (1) according to one of the preceding claims, wherein the connection arrangement (1) has a sensor (13) which is designed in particular as a current sensor, voltage sensor, and / or combined current and voltage sensor.

6. Connection arrangement (1) according to one of the preceding claims, wherein the two inner conductors (2, 4) are designed in the form of two conductor halves with a semicircular cross-section and are separated from one another by a dielectric.

7. Connection arrangement (1) according to one of the preceding claims, wherein the connection arrangement (1) is designed for a predeterminable RF impedance, which is in particular based on the impedance of the intended connection of the connection arrangement (1).

8. Plasma process power supply system (10), comprising a first DC power supply (5), a second DC power supply (8), an RF power supply (3) and a connection arrangement (1) according to one of the preceding claims, which establishes the following connections: a) connection of the first DC power supply (5) to the first inner conductor (2) of the connection arrangement (1); b) connection of the second DC power supply (8) to the second inner conductor (4) of the connection arrangement (1); c) connection of the RF power supply (3) to both inner conductors (2, 4) of the connection arrangement (1).

9. Plasma process power supply system (10) according to the preceding claim 8, comprising an impedance matching circuit (7) which can be connected to the power supplies (3, 5, 8) by means of the connection arrangement (1).

10. Plasma process power supply system (10) according to the preceding claim 9, wherein a further connection arrangement (1) is connected to the impedance matching circuit (7) for connection to a possible load, e.g. a plasma process chamber.

11. Plasma process system (12) comprising a plasma process power supply system (10) according to one of the preceding claims 8 to 10 and a plasma process arrangement (6) connected via the connection arrangement (1) according to one of claims 1 to 7, said arrangement having two electrodes for connecting one of the two inner conductors (2, 4) in each case.

12. Part of a plasma processing system comprising an impedance matching circuit (7), a plasma processing arrangement (6) and a connection arrangement (1) according to one of the preceding claims 1 to 7, which establishes a connection between the impedance matching circuit (7) and the plasma processing arrangement (6).

13. A method for operating a plasma process in a plasma process arrangement (6) in a plasma process system (12) according to claim 11, comprising the steps of: a) providing a first DC voltage via a first inner conductor (2) of the connection arrangement (1) to a plasma process arrangement (6) by a first DC power supply (5) b) providing a second DC voltage via a second inner conductor (4) of the connection arrangement (1) to a plasma process arrangement (6) by a second DC power supply (8) c) transmitting an RF power signal from the RF power supply (3) to the plasma processing arrangement (6) via the two inner conductors (2, 4) of the connecting arrangement (1) d) generation of plasma in the plasma processing arrangement (6)

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