A pre-matcher for plasma load and a method for adjusting the same
Patent Information
- Application Number
- CN202611188185.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-06
- Publication Date
- 2026-10-27
AI Technical Summary
当负载阻抗发生变化时，射频传输过程中容易产生较大的反射功率和驻波效应，降低射频功率向等离子体负载的注入效率，并影响等离子体放电稳定性及系统运行可靠性
[0034]本发明在射频源与等离子体负载之间设置预匹配阻抗变换结构，通过预匹配器对等离子体负载阻抗进行预补偿，并结合可调平板电容设计，通过调节电容极板铺铜面积改变等效电容值，实现预匹配器输入阻抗的连续调节，以适应等离子体负载阻抗的动态变化。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of radio frequency power transmission and impedance matching technology, and in particular relates to a pre-matching device for plasma loads and its adjustment method. Background Technology
[0002] Plasma is widely used in semiconductor process equipment, plasma-enhanced process equipment, low-energy high-current ion implantation equipment, fusion reactors, gas discharge, surface treatment, and sterilization. In these applications, radio frequency (RF) power sources are typically used to generate RF power, which is then coupled to the plasma load via a matching network consisting of a pre-matched unit and a matched unit. This allows for efficient injection of RF power into the plasma load, exciting and maintaining the plasma discharge, and achieving a stable process. In low-energy high-current ion implantation equipment and fusion plasma applications, stable plasma discharge is crucial for ion generation, ion implantation, stable ion beam output, and ion energy control. Therefore, high demands are placed on RF power transmission efficiency, impedance matching performance, and system operational stability.
[0003] The main function of the matching network is to achieve impedance matching between the RF power source and the plasma load, improve the transmission efficiency of RF power to the plasma load, reduce reflected power and VSWR, thereby ensuring the stability of plasma discharge and the reliability of RF system operation. However, the plasma load has obvious nonlinear and time-varying characteristics. Its impedance changes continuously with factors such as input power, gas pressure, gas composition, plasma density and process conditions, causing continuous fluctuations in the overall system impedance and easily leading to impedance mismatch.
[0004] Most existing pre-matched circuits are designed based on experience or fixed load models, and their parameters are usually optimized for a specific operating point. When the load impedance changes, large reflected power and standing wave effects are easily generated during RF transmission, reducing the injection efficiency of RF power into the plasma load and affecting the stability of plasma discharge and the reliability of system operation. Existing technologies typically require the detection of parameters such as reflected power, voltage, and current, and real-time adjustment of matching parameters through feedback control. This adjustment method is not only complex and slow in response, but also makes it difficult to balance adjustment efficiency and matching accuracy.
[0005] In addition, existing pre-matched circuits are generally designed for specific matching circuits and application scenarios, resulting in poor versatility and difficulty in adapting to matching circuits with different structures and parameters. At the same time, some pre-matched circuits still have problems such as large structural size and insufficient high-temperature resistance. Under high-temperature and high-power continuous operation conditions, they are prone to parameter drift and matching performance degradation, making it difficult to meet the requirements of long-term stable operation and impedance matching performance in different application scenarios. Summary of the Invention
[0006] The purpose of this invention is to provide a pre-matching device for plasma loads and its adjustment method.
[0007] This invention is achieved through the following technical solution:
[0008] The present invention is a pre-matching device for a plasma load, comprising an input connector and a pre-matching network, wherein the pre-matching network comprises a first branch and a second branch;
[0009] The first branch includes a first inductor and a first capacitor connected together, and the other end of the first inductor is electrically connected to the metal shielding shell through a conductive fastener.
[0010] The second branch includes a connected second capacitor and a second inductor. The other end of the second inductor is connected to the output connector, and the output connector is connected to the load.
[0011] One electrode of the first capacitor and the second capacitor are connected to a common capacitor plate.
[0012] The input connector is electrically connected to the common capacitor plate and is used to introduce radio frequency input signals.
[0013] By changing the copper plating area on the capacitor plates of the first and second capacitors, the input impedance of the pre-matching unit is adjusted, thereby pre-compensating the plasma load impedance and adjusting the impedance matching state of the RF power transmission system.
[0014] Furthermore, both the first capacitor and the second capacitor are parallel plate capacitors. Each parallel plate capacitor consists of two copper foil conductive layers disposed on both sides of the alumina ceramic substrate. The alumina ceramic substrate serves as the dielectric layer of the parallel plate capacitor. The equivalent capacitance value of the parallel plate capacitor is changed by adjusting the copper area of the copper foil conductive layers.
[0015] Capacitors satisfy the formula:
[0016] Where C represents the capacitance value of the parallel plate capacitor. The distance between the plates. The area of the electrode plate is... Where is the dielectric constant. The vacuum permittivity is approximately 8.854. F / m, The relative permittivity of the dielectric between the plates is used. The dielectric constant of the ceramic substrate is 9.8.
[0017] Furthermore, the first capacitor, the second capacitor, the first inductor, and the second inductor are all disposed on the alumina ceramic substrate. The alumina ceramic substrate is formed by stacking seven alumina ceramic layers, each with a thickness of 1 mm. The dimensions of the alumina ceramic substrate are 150 mm × 150 mm × 7 mm.
[0018] Both the first and second inductors are formed by continuously winding metal conductors along a plane on the surface of an alumina ceramic substrate.
[0019] Furthermore, the first inductor is formed by a turn-plane spiral copper foil conductor laid on the surface of the alumina ceramic substrate, and the second inductor is formed by a turn-plane spiral copper foil conductor laid on the surface of the alumina ceramic substrate. The line width of the copper foil conductor is 4 mm, and the spacing between adjacent turns of copper foil conductor is 2 mm.
[0020] Where L is the inductance value of the planar spiral inductor. and These are empirical constants related to the coil geometry, used to correct calculations for planar spiral inductors of different shapes. For square planar spiral inductors, Take 2.34, Take 2.75, It is a vacuum permeability of 4 H / m, Number of turns It is the average diameter. This is the fill factor.
[0021] Furthermore, the first capacitor plate of the first capacitor and the first capacitor plate of the second capacitor are composed of a copper foil conductive layer formed on the lower surface of the fourth layer of alumina ceramic substrate, and together they form a common capacitor plate.
[0022] The input connector is electrically connected to the common capacitor plate for introducing radio frequency input signals;
[0023] The copper foil conductors of the first and second inductors are respectively formed on the upper surface of the fourth layer of alumina ceramic substrate.
[0024] Furthermore, the equivalent impedance of the load in the system satisfies the complex impedance formula;
[0025] in, The equivalent complex impedance of the plasma load is given. This is the load equivalent resistance component. The load equivalent reactance component, Let z be the reference characteristic impedance, and z be the normalized impedance. The imaginary unit is used; the parameters of the first capacitor, second capacitor, first inductor, and second inductor in the pre-matching device are determined based on the resistive and reactive components in the equivalent impedance of the load, so as to realize the pre-compensation and impedance transformation of the plasma load impedance.
[0026] Furthermore, the reactive component of the load impedance is compensated by introducing capacitors and inductors, and the component parameters satisfy the following formulas:
[0027] Where f is the radio frequency operating frequency, C is the capacitance value of the first capacitor or the second capacitor, and L is the inductance value of the first inductor or the second inductor. This is the capacitive reactance of the capacitor. This refers to the inductive reactance of the inductor.
[0028] Based on the calculated initial parameters, a pre-matching impedance compensation network is established. The equivalent capacitance value is changed by adjusting the copper plating area of the first and second capacitor plates to adjust the input impedance of the pre-matching device, thereby achieving pre-compensation and impedance matching of the plasma load impedance.
[0029] The pre-matching network conditioning method, using one of the pre-matching devices for plasma loads described above, includes:
[0030] The initial parameters of the pre-matched circuit are determined based on the target impedance of the plasma load, wherein the initial capacitance values of the first capacitor and the second capacitor are both 300 pF, the inductance value of the first inductor is 250 nH, and the inductance value of the second inductor is 1000 nH.
[0031] Keeping the inductance values of the first and second inductors constant, the equivalent capacitance values of the first and second capacitors are changed by adjusting the copper plating area of their capacitor plates, thereby adjusting the input impedance of the pre-matching circuit.
[0032] Furthermore, based on the deviation between the target matching impedance and the input impedance of the pre-matching device, the copper plating area of the capacitor plates of the first and second capacitors is gradually adjusted, and electromagnetic simulation is performed on the adjusted pre-matching device to obtain the equivalent impedance of the output terminal of the pre-matching device facing the load side. The above adjustment and simulation process is repeated until the equivalent impedance and the target load impedance form a conjugate matching relationship. When the copper plating width of the capacitor plates of the first and second capacitors is 40 mm, the simulation shows that the equivalent impedance of the output terminal of the pre-matching device facing the load side is 5.2 + j30.1 Ω, which forms a conjugate matching relationship with the load impedance 5 − j30 Ω.
[0033] The present invention has the following beneficial effects:
[0034] This invention sets up a pre-matched impedance transformation structure between the radio frequency source and the plasma load. The pre-matched device pre-compensates the impedance of the plasma load and combines it with an adjustable parallel plate capacitor design. By adjusting the copper area of the capacitor plate, the equivalent capacitance value is changed, thereby realizing the continuous adjustment of the input impedance of the pre-matched device to adapt to the dynamic changes in the impedance of the plasma load.
[0035] By combining the pre-matched impedance transformation structure with the adjustable parallel plate capacitor, continuous compensation of the plasma load impedance can be achieved, enabling the pre-matched input impedance to form a conjugate match with the target load impedance. This effectively reduces reflected power and VSWR during RF transmission, improves RF power transmission efficiency and impedance matching accuracy, enhances the system's adaptability to dynamic changes in load impedance, and improves system stability. Furthermore, while maintaining the overall topology of the pre-matched device, different impedance matching parameters can be configured simply by adjusting the copper plating area of the parallel plate capacitor. This improves the pre-matched device's adaptability to different matchers and operating conditions, enhancing the flexibility of engineering applications.
[0036] An integrated ceramic structure combining a planar spiral inductor and a parallel plate capacitor is adopted, integrating the inductor and capacitor on the same ceramic substrate. At the same time, by optimizing the copper plating area of the parallel plate capacitor, different matching parameters can be designed to meet the application requirements of different operating frequencies, load conditions and matching network topologies while keeping the overall topology of the pre-matching unit unchanged.
[0037] Ceramic integrated structures can reduce parasitic parameters generated by device interconnection, reduce network insertion loss, and improve impedance transformation accuracy. At the same time, by utilizing the characteristics of ceramic materials such as high temperature resistance, low dielectric loss, high insulation strength, and good thermal stability, the pre-matched circuit can be used in complex operating conditions such as high temperature and high power, thereby improving the reliability and stability of system operation.
[0038] Furthermore, by optimizing the copper plating area to configure the pre-matching parameters, the matching requirements of different operating frequencies and load conditions can be met while maintaining the overall network topology, thereby improving the flexibility of network design and the convenience of engineering implementation.
[0039] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description
[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0041] Figure 1 This is a schematic diagram of the internal pre-matching circuit structure of the pre-matching device of the present invention;
[0042] Figure 2 This is a schematic diagram of the main structure of the pre-matching device of the present invention;
[0043] Figure 3This is a top view of the pre-matching device of the present invention;
[0044] Figure 4 Simulation results of the Smith chart of the output impedance variation of the pre-matching circuit under different capacitor plate lengths (Part 1).
[0045] Figure 5 Simulation results of the Smith chart of the output impedance variation of the pre-matching circuit under different capacitor plate lengths (Part 2).
[0046] The attached diagram lists the components represented by each number as follows:
[0047] 1. Input connector; 2. Output connector; 3. First capacitor; 4. Second capacitor; 5. First inductor; 6. Second inductor; 7. Common capacitor plate; 8. Alumina ceramic substrate; 9. Conductive fastener; 10. Metal shielding shell. Detailed Implementation
[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0049] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.
[0050] Please see Figure 1-3 As shown, the present invention is a pre-matching device for plasma loads.
[0051] Input connector 1 and pre-matching network, the pre-matching network including a first branch and a second branch;
[0052] The first branch includes a first inductor 5 and a first capacitor 3 connected together. The other end of the first inductor 5 is electrically connected to the metal shielding shell 10 through a conductive fastener 9. The metal shielding shell 10 serves as the grounding reference conductor of the pre-matching device.
[0053] The second branch includes a second capacitor 4 and a second inductor 6 connected together. The other end of the second inductor 6 is connected to the output connector 2, which is connected to the load, i.e., the output connector 2 is connected to the plasma load.
[0054] One electrode of the first capacitor 3 and the second capacitor 4 are connected together to a common capacitor plate 7. The input connector 1 is electrically connected to the common capacitor plate 7 to introduce radio frequency input signals.
[0055] Among them, the first capacitor 3 and the second capacitor 4 are both parallel plate capacitors. Each parallel plate capacitor consists of two copper foil conductive layers disposed on both sides of the alumina ceramic substrate 8. The alumina ceramic substrate 8 serves as the dielectric layer of the parallel plate capacitor. The equivalent capacitance value of the parallel plate capacitor is changed by adjusting the copper area of the copper foil conductive layer.
[0056] The first capacitor 3 and the second capacitor 4 are not fixed parameters, but their capacitance values are continuously adjustable by adjusting the copper plating area of the corresponding capacitor plates. By changing the copper plating geometry, effective coupling area or structural parameters, the equivalent capacitance value is changed, thereby adjusting the input impedance of the pre-matching device, so that the pre-matching device can adapt to impedance changes under different load conditions and achieve target impedance matching between the RF source and the plasma load.
[0057] In the real-time example, the initial design values of the first capacitor 3 and the second capacitor 4 are both 300 pF, the initial design value of the first inductor 5 is 250 nH, and the initial design value of the second inductor 6 is 1000 nH.
[0058] Specifically, the above parameters, combined with the target operating frequency of the pre-matched circuit, the target load impedance range, and the impedance transformation requirements, are determined through circuit theory calculations and electromagnetic simulations to serve as the initial parameter combination for the pre-matched circuit and are used for subsequent parameter optimization.
[0059] Capacitors satisfy formula (1): (1)
[0060] Where C represents the capacitance value of the parallel plate capacitor. The distance between the plates. The area of the electrode plate is... Where is the dielectric constant. The vacuum permittivity is approximately 8.854. F / m, The relative permittivity of the dielectric between the plates is used. The dielectric constant of the ceramic substrate is 9.8.
[0061] In addition, the first capacitor 3, the second capacitor 4, the first inductor 5 and the second inductor 6 are all disposed on the alumina ceramic substrate 8. The alumina ceramic substrate 8 is formed by stacking seven alumina ceramic layers, each with a thickness of 1 mm. The dimensions of the alumina ceramic substrate 8 are 150 mm × 150 mm × 7 mm.
[0062] The first inductor 5 and the second inductor 6 are formed as planar spiral inductors. Both the first inductor 5 and the second inductor 6 are formed by continuously winding a metal conductor formed on the surface of the alumina ceramic substrate 8 along a plane.
[0063] Furthermore, the first inductor 5 is formed by two turns of planar spiral copper foil conductors laid on the surface of the alumina ceramic substrate 8, and the second inductor 6 is formed by four turns of planar spiral copper foil conductors laid on the surface of the alumina ceramic substrate 8. The line width of the copper foil conductors is 4 mm, and the spacing between adjacent turns of copper foil conductors is 2 mm. The inductance value is calculated according to formula (2).
[0064] (2)
[0065] Where L is the inductance value of the planar spiral inductor. and These are empirical constants related to the coil geometry, used to correct calculations for planar spiral inductors of different shapes. For square planar spiral inductors, Take 2.34, Take 2.75, It is a vacuum permeability of 4 H / m, Number of turns It is the average diameter. This is the fill factor.
[0066] The copper foil conductors of the first inductor 5 and the second inductor 6 are respectively formed on the upper surface of the fourth layer of alumina ceramic substrate 8.
[0067] Furthermore, the equivalent impedance of the load in the system satisfies the complex impedance formula (3).
[0068] (3)
[0069] in, The equivalent complex impedance of the plasma load is given. This is the load equivalent resistance component. The load equivalent reactance component, Let z be the reference characteristic impedance, and z be the normalized impedance. The imaginary unit is used; the parameters of the first capacitor 3, the second capacitor 4, the first inductor 5 and the second inductor 6 in the pre-matching device are determined according to the resistive and reactive components in the equivalent impedance of the load, so as to realize the pre-compensation and impedance transformation of the plasma load impedance.
[0070] Furthermore, the first capacitor plate of the first capacitor 3 and the first capacitor plate of the second capacitor 4 are composed of a copper foil conductive layer formed on the lower surface of the alumina ceramic substrate 8 in the fourth layer, and together they form a common capacitor plate 7.
[0071] When the copper plating width of the capacitor plates of both capacitor 3 and capacitor 4 is adjusted to 40 mm, the electromagnetic simulation yields a normalized impedance of 0.1040 + j0.6020 at the output of the pre-matched circuit towards the load side. Based on the 50Ω characteristic impedance, the actual equivalent impedance is calculated as follows:
[0072] Z = (0.1040+j0.6020)×50=5.2+j30.1Ω
[0073] This equivalent impedance and plasma load impedance =5-30jΩ satisfies the conjugate matching relationship.
[0074] Input connector 1 is electrically connected to the common capacitor plate 7, and input connector 1 is used to introduce radio frequency input signals.
[0075] By changing the copper plating area of the capacitor plates on the first capacitor 3 and the second capacitor 4, the input impedance of the pre-matching device is adjusted, thereby pre-compensating the plasma load impedance and adjusting the impedance matching state of the RF power transmission system.
[0076] Furthermore, the reactive component of the load impedance is compensated by introducing capacitors and inductors, where the capacitor value satisfies formula (4) and the inductor value satisfies formula (5):
[0077] (4)
[0078] (5)
[0079] Where f is the radio frequency operating frequency, C is the capacitance value of the first capacitor 3 or the second capacitor 4, and L is the inductance value of the first inductor 5 or the second inductor 6. This is the capacitive reactance of the capacitor. This is the inductive reactance of the inductor.
[0080] Based on the calculated initial parameters, a pre-matching impedance compensation network is established. The equivalent capacitance value is changed by adjusting the copper plating area of the first capacitor 3 and the second capacitor 4 to adjust the input impedance of the pre-matching device, thereby achieving pre-compensation and impedance matching of the plasma load impedance.
[0081] The pre-matching network conditioning method, using one of the pre-matching devices for plasma loads described above, includes:
[0082] The initial parameters of the pre-matching device are determined based on the target impedance of the plasma load, wherein the initial capacitance values of the first capacitor 3 and the second capacitor 4 are both 300 pF, the inductance value of the first inductor 5 is 250 nH, and the inductance value of the second inductor 6 is 1000 nH.
[0083] Keeping the inductance values of the first inductor 5 and the second inductor 6 constant, the equivalent capacitance value is changed by adjusting the copper plating area of the capacitor plates of the first capacitor 3 and the second capacitor 4, thereby adjusting the input impedance of the pre-matching circuit.
[0084] Furthermore, based on the deviation between the target matching impedance and the input impedance of the pre-matching device, the copper plating area of the capacitor plates of the first capacitor 3 and the second capacitor 4 is gradually adjusted, and electromagnetic simulation is performed on the adjusted pre-matching device to obtain the equivalent impedance of the output terminal of the pre-matching device facing the load side; the above adjustment and simulation process is repeated until the equivalent impedance and the target load impedance form a conjugate matching relationship; when the copper plating width of the capacitor plates of the first capacitor 3 and the second capacitor 4 is 40 mm, the simulation shows that the equivalent impedance of the output terminal of the pre-matching device facing the load side is 5.2 + j30.1 Ω, which forms a conjugate matching relationship with the load impedance 5 − j30 Ω.
[0085] like Figure 4 and Figure 5 As shown, Figure 4 and Figure 5 The figures show the Smith chart simulation results obtained by parametric scanning of the copper plating width of the capacitor plates of the first capacitor 3 and the second capacitor 4 within the range of 30 mm to 50 mm using electromagnetic simulation software. As the copper plating width changes, the impedance point of the pre-matched circuit output terminal facing the load side moves along different trajectories on the Smith chart. The position marked by the red box in the figure is the optimized target impedance point, whose corresponding normalized impedance is 0.1040 + j0.6020. Since the Smith chart uses a 50 Ω characteristic impedance for normalization, multiplying the normalized impedance by 50 Ω yields the actual equivalent impedance of 5.2 + j30.1 Ω. This impedance forms a conjugate matching relationship with the plasma load impedance of 5 − j30 Ω, indicating that by adjusting the copper plating width of the capacitor plates of the first capacitor 3 and the second capacitor 4, the output impedance of the pre-matched circuit can be effectively optimized. Through the above structure and adjustment method, the pre-matching network can perform impedance transformation and pre-compensation on the load impedance, so that the RF transmission system maintains a good impedance matching state, reduces the VSWR and reflected power, and improves the RF power transmission efficiency and system operation stability.
[0086] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0087] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A pre-matching device for a plasma load, comprising an input connector (1), characterized in that: It also includes a pre-matching network, which includes a first branch and a second branch; The first branch includes a first inductor (5) and a first capacitor (3) connected together. The other end of the first inductor (5) is electrically connected to the metal shielding shell (10) through a conductive fastener (9). The second branch includes a second capacitor (4) and a second inductor (6) connected together. The other end of the second inductor (6) is connected to an output connector (2), which is connected to a load. One end electrode of the first capacitor (3) and the second capacitor (4) are connected to a common capacitor plate (7); The input connector (1) is electrically connected to the common capacitor plate (7), and the input connector (1) is used to introduce radio frequency input signals; By changing the copper plating area of the capacitor plates on the first capacitor (3) and the second capacitor (4), the input impedance of the pre-matching device is adjusted, thereby pre-compensating the plasma load impedance and adjusting the impedance matching state of the radio frequency power transmission system.
2. A pre-matching device for a plasma load according to claim 1, characterized in that, The first capacitor (3) and the second capacitor (4) are both plate capacitors. Each plate capacitor is composed of two copper foil conductive layers disposed on both sides of the alumina ceramic substrate (8). The alumina ceramic substrate (8) serves as the dielectric layer of the plate capacitor. The equivalent capacitance value of the plate capacitor can be changed by adjusting the copper area of the copper foil conductive layer. Capacitors satisfy the formula: Where C represents the capacitance value of the parallel plate capacitor. The distance between the plates. The area of the electrode plate is... Where is the dielectric constant. The vacuum permittivity, The relative permittivity of the dielectric between the plates is used. The dielectric constant of the ceramic substrate is 9.
8.
3. A pre-matching device for a plasma load according to claim 2, characterized in that, The first capacitor (3), the second capacitor (4), the first inductor (5) and the second inductor (6) are all disposed on the alumina ceramic substrate (8). The alumina ceramic substrate (8) is formed by stacking seven layers of alumina ceramic with a thickness of 1 mm. The size of the alumina ceramic substrate (8) is 150 mm × 150 mm × 7 mm. The first inductor (5) and the second inductor (6) are both formed by continuously winding a metal conductor along a plane on the surface of an alumina ceramic substrate (8).
4. A pre-matching device for a plasma load according to claim 3, characterized in that, The first inductor (5) is formed by two turns of planar spiral copper foil conductors laid on the surface of the alumina ceramic substrate (8), and the second inductor (6) is formed by four turns of planar spiral copper foil conductors laid on the surface of the alumina ceramic substrate (8). The line width of the copper foil conductors is 4 mm, and the spacing between adjacent turns of copper foil conductors is 2 mm. Where L is the inductance value of the planar spiral inductor. and These are empirical constants related to the coil geometry, used to correct calculations for planar spiral inductors of different shapes. For square planar spiral inductors, Take 2.34, Take 2.75, It is the vacuum permeability. Number of turns It is the average diameter. This is the fill factor.
5. A pre-matching device for a plasma load according to claim 4, characterized in that, The first capacitor plate of the first capacitor (3) and the first capacitor plate of the second capacitor (4) are composed of a copper foil conductive layer formed on the lower surface of the alumina ceramic substrate (8) in the fourth layer, and together form a common capacitor plate (7). The input connector (1) is electrically connected to the common capacitor plate (7) for introducing radio frequency input signals; The copper foil conductors of the first inductor (5) and the second inductor (6) are respectively formed on the upper surface of the alumina ceramic substrate (8) of the fourth layer.
6. A pre-matching device for a plasma load according to claim 5, characterized in that, The equivalent impedance of the load in the system satisfies the complex impedance formula; in, The equivalent complex impedance of the plasma load is given. This is the load equivalent resistance component. The load equivalent reactance component, Let z be the reference characteristic impedance, and z be the normalized impedance. The imaginary unit is used; the parameters of the first capacitor (3), the second capacitor (4), the first inductor (5) and the second inductor (6) in the pre-matching device are determined according to the resistive and reactive components in the equivalent impedance of the load, so as to realize the pre-compensation and impedance transformation of the plasma load impedance.
7. A pre-matching device for a plasma load according to claim 6, characterized in that, The reactive component of the load impedance is compensated by introducing capacitors and inductors, and the component parameters satisfy the following formulas: Where f is the radio frequency operating frequency, C is the capacitance value of the first capacitor (3) or the second capacitor (4), and L is the inductance value of the first inductor (5) or the second inductor (6). This is the capacitive reactance of the capacitor. This refers to the inductive reactance of the inductor. Based on the calculated initial parameters, a pre-matching impedance compensation network is established, and the equivalent capacitance value is changed by adjusting the copper plating area of the first capacitor (3) and the second capacitor (4) to adjust the input impedance of the pre-matching device, thereby achieving pre-compensation and impedance matching of the plasma load impedance.
8. A pre-matching network adjustment method, using a pre-matching device for a plasma load as described in claim 7, characterized in that, include: The initial parameters of the pre-matched circuit are determined based on the target impedance of the plasma load, wherein the initial capacitance values of the first capacitor (3) and the second capacitor (4) are both 300 pF, the inductance value of the first inductor (5) is 250 nH, and the inductance value of the second inductor (6) is 1000 nH. Keeping the inductance values of the first inductor (5) and the second inductor (6) unchanged, the equivalent capacitance value of the capacitor plates of the first capacitor (3) and the second capacitor (4) is changed by adjusting the copper plating area, so as to adjust the input impedance of the pre-matching circuit.
9. The pre-matching network adjustment method according to claim 8, characterized in that, Also includes: Based on the deviation between the target matching impedance and the input impedance of the pre-matching device, the copper plating area of the capacitor plates of the first capacitor (3) and the second capacitor (4) is gradually adjusted, and electromagnetic simulation is performed on the adjusted pre-matching device to obtain the equivalent impedance of the output terminal of the pre-matching device facing the load side; the above adjustment and simulation process is repeated until the equivalent impedance and the target load impedance form a conjugate matching relationship; when the copper plating width of the capacitor plates of the first capacitor (3) and the second capacitor (4) is 40 mm, the simulation shows that the equivalent impedance of the output terminal of the pre-matching device facing the load side is 5.2+j30.1 Ω, which forms a conjugate matching relationship with the load impedance 5−j30Ω.