A radio frequency matching circuit for glow under high vacuum

Abstract

The utility model relates to vacuum plasma technical field especially relates to a radio frequency matching device circuit for high vacuum under glow, is applicable to 10 high vacuum environment under -3Pa and below fast steady start glow and maintain glow. The radio frequency matching device circuit includes: radio frequency input, radio frequency output and the matching network that constitutes by adjustable capacitance, fixed inductance series connection in proper order for the accurate matching of radio frequency source and cavity impedance, direct current high voltage isolation output power module and core -piercing capacitance, inductance filter network are arranged in parallel in radio frequency output, are used for in high vacuum cavity first apply 1kV -2kV direct current high voltage ignition and isolate radio frequency signal interference, the core -piercing capacitance withstand voltage is not less than 3kV, inductance 10 -100muH, and the low pass filter that both cooperations constitute. Through direct current high voltage first ignition, again by radio frequency signal maintains glow, the utility model can realize reliable start under high vacuum without vacuum switching process, significantly improves the start glow success rate and reduces the process cycle.

Description

Technical Field

[0001] This utility model relates to the field of vacuum plasma technology, and in particular to a radio frequency matching circuit for glow discharge under high vacuum. Background Technology

[0002] As radio frequency (RF) applications become increasingly widespread, users are placing increasingly stringent demands on RF usage conditions, especially requiring stable RF ignition under high vacuum conditions. However, in high vacuum environments of 10⁻³ Pa and below, the probability of electron-ion collisions drops sharply, making it difficult to achieve effective glow discharge solely through RF excitation. Existing processes typically employ a two-stage procedure: ignition at a lower vacuum level (e.g., 10⁻¹ Pa) followed by evacuation to the target high vacuum. While this ensures a high ignition success rate, it results in long overall vacuum switching times, complex processes, and the potential for introducing contamination into the vacuum pump system, failing to meet the demands of modern industrial plasma processing for high efficiency, cleanliness, and automation. Therefore, designing an RF matching circuit for glow discharge under high vacuum is essential. Utility Model Content

[0003] The purpose of this invention is to provide an RF matching circuit for glow discharge under high vacuum, so as to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a radio frequency matching circuit for glow discharge under high vacuum, the radio frequency matching circuit comprising: RF input terminal RF IN and RF output terminal RF OUT; The matching network, consisting of a first adjustable capacitor CL, a fixed inductor L1, and a second adjustable capacitor CT connected in parallel, is used to match the impedance of the radio frequency source with that of the cavity. The DC high voltage device DC is a DC high voltage isolated output power supply module, which, together with the core capacitor C1 and the wire-wound inductor L2, forms a filter network and is arranged in parallel at the RF output terminal RF OUT. It is used to first apply DC high voltage to the high vacuum cavity for ignition and isolate the RF signal. The through-core capacitor C1 and the wire-wound inductor L2 work together to form a low-pass filter to prevent radio frequency signals from interfering with the DC high-voltage module.

[0005] According to the above technical solution, the capacitance range of the first adjustable capacitor CL is 10pF to 1300pF, and the withstand voltage is not less than 3kV.

[0006] According to the above technical solution, the inductance of the fixed inductor L1 is 0.3μH to 1μH, and the Q value is ≥100 (frequency 13.56MHz).

[0007] According to the above technical solution, the capacitance range of the second adjustable capacitor CT is 10pF to 400pF, and the withstand voltage is not less than 3kV.

[0008] According to the above technical solution, the output voltage of the DC high-voltage isolated output power supply module is 1kV to 2kV.

[0009] According to the above technical solution, the capacitance of the through-core capacitor C1 is 1nF to 10nF, and the withstand voltage is not less than 3kV.

[0010] According to the above technical solution, the inductance of the wire-wound inductor L2 is 10μH to 100μH.

[0011] According to the above technical solution, the RF input terminal RF IN adopts an N-type coaxial connector and forms an electrical shield with the matching unit's bottom shell.

[0012] Compared with the prior art, the beneficial effects achieved by this utility model are as follows: This utility model, by connecting a DC high-voltage isolated output power supply module and a through-core capacitor C1-wire-wound inductor L2 filter network in parallel at the output end of the RF matching unit, achieves rapid ignition and glow discharge in a high vacuum chamber with a 1kV–2kV DC high voltage first, and then maintains the discharge by the RF signal. It eliminates the need to start up and switch the vacuum level at a lower vacuum level, significantly simplifies the process, shortens the start-up time, and greatly improves the RF start-up success rate and discharge stability in high vacuum environments of 10⁻³Pa and below. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a connection diagram of an RF matching circuit for glow discharge under high vacuum, as proposed in this utility model. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] Example: Reference Figure 1A radio frequency matching circuit for glow discharge under high vacuum includes a radio frequency input terminal RF IN, a radio frequency output terminal RF OUT, a matching circuit, and a DC high voltage device DC. The matching circuit is composed of a first adjustable capacitor CL, a fixed inductor L1, and a second adjustable capacitor CT coupled together. One end of the first adjustable capacitor CL is electrically connected to the radio frequency input terminal RF IN via an N-type coaxial connector, and the other end is grounded by bolt welding. The capacitance range is 10–1300pF, and the withstand voltage is not less than 3kV. It is used for primary reactance compensation of the input impedance. The fixed inductor L1 is connected in series between the first adjustable capacitor CL and the second adjustable capacitor CT. The inductance is 0.3–1μH, and the Q value is ≥100 (13.56MHz). The capacitance range of the second adjustable capacitor CT is 10pf to 400pf. One end is electrically connected to the junction of the fixed inductor L1, and the other end is connected to the matching circuit output via a thread. It is used for fine adjustment of the matching point.

[0016] The DC high-voltage device (DC) is a DC high-voltage isolated output power supply module, which is fixedly connected to the upper end of the through-core capacitor C1 via high-voltage leads. The lower end of the through-core capacitor C1 is electrically connected to the input end of the wire-wound inductor L2 via epoxy soldering. The output end of the wire-wound inductor L2 is soldered to the RF output terminal RF OUT. The through-core capacitor C1 is a ceramic through-core capacitor with a withstand voltage of not less than 3kV and a capacitance of 1nF–10nF, used to isolate RF signals under DC voltage. The wire-wound inductor L2 has an inductance of 10–100μH and is soldered onto the circuit board using insulated leads. Together, they achieve low-pass filtering of RF signals and prevent RF backflow to the DC power supply.

[0017] The workflow of this embodiment is as follows: When the RF power supply is not yet connected, the DC high-voltage isolated output power supply module first applies a 1kV–2kV DC high voltage to the high vacuum cavity through the RF output terminal RF OUT, causing glow discharge to occur inside the cavity. Subsequently, the RF power supply is turned on, and the RF signal enters the cavity after being matched by the first adjustable capacitor CL, the fixed inductor L1, and the second adjustable capacitor CT, maintaining a stable glow discharge together with the DC high voltage. By fine-tuning the first adjustable capacitor CL and the second adjustable capacitor CT, the optimal impedance matching between the RF source and the cavity can be achieved; the filtering effect of the through-core capacitor C1 and the wire-wound inductor L2 can effectively prevent the RF signal from interfering with the DC high-voltage module. Using this embodiment, the glow discharge of the high vacuum cavity can be quickly and reliably lit without changing the vacuum pumping process, and the discharge can be kept stable, thereby significantly improving the start-up success rate and operational reliability of the RF glow discharge in a high vacuum environment.

[0018] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0019] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A radio frequency matching circuit for glow discharge under high vacuum, characterized in that, The radio frequency matching circuit includes: RF input terminal RF IN and RF output terminal RF OUT; The matching network, consisting of a first adjustable capacitor CL, a fixed inductor L1, and a second adjustable capacitor CT connected in parallel, is used to match the impedance of the radio frequency source with that of the cavity. The DC high voltage device DC is a DC high voltage isolated output power supply module, which, together with the core capacitor C1 and the wire-wound inductor L2, forms a filter network and is arranged in parallel at the RF output terminal RF OUT. It is used to first apply DC high voltage to the high vacuum cavity for ignition and isolate the RF signal. The through-core capacitor C1 and the wire-wound inductor L2 work together to form a low-pass filter to prevent radio frequency signals from interfering with the DC high-voltage module.

2. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The capacitance range of the first adjustable capacitor CL is 10pF to 1300pF, and the withstand voltage is not less than 3kV.

3. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The inductance of the fixed inductor L1 is 0.3μH to 1μH, and the Q value is ≥100 (frequency 13.56MHz).

4. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The capacitance range of the second adjustable capacitor CT is 10pF to 400pF, and the withstand voltage is not less than 3kV.

5. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The DC high-voltage isolated output power supply module has an output voltage of 1kV to 2kV.

6. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The capacitance of the through-core capacitor C1 is 1nF to 10nF, and the withstand voltage is not less than 3kV.

7. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The inductance of the wire-wound inductor L2 is 10μH to 100μH.

8. The radio frequency matching circuit for glow discharge under high vacuum according to claim 1, characterized in that, The RF input terminal RF IN uses an N-type coaxial connector and forms an electrical shield with the matching unit's bottom shell.

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