Impedance matching method and matching device

Abstract

The present invention provides an impedance matching method and matching device, comprising: determining whether plasma ignition is successful; if not, using a preset ignition algorithm to calculate the adjustment direction and adjustment amount of an impedance variable element, and adjusting the value of the impedance variable element based on the adjustment direction and adjustment amount; if successful, calculating the current load impedance based on the voltage signal, current signal, and angle difference signal detected at the output end of the impedance matching network, and obtaining a target value of the impedance variable element based on the load impedance; and adjusting the value of the impedance variable element step by step according to multiple set step sizes and set speeds corresponding to each set step size based on the current value and target value of the impedance variable element, so as to simultaneously adjust the load impedance from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point. The impedance matching method provided by the present invention can achieve stable ignition and stable matching of the matching device.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to an impedance matching method and a matching device. Background Art

[0002] RF signals are widely used as plasma excitation sources in semiconductor equipment, such as etching equipment, physical vapor deposition (PVD) equipment, and plasma-enhanced chemical vapor deposition (PECVD) equipment. In these devices using RF systems, an RF power supply provides RF energy to the chamber to ionize the process gas in a high vacuum state, generating a plasma containing a large number of active particles such as electrons, ions, excited atoms, molecules, and free radicals. These active particles interact with the wafer placed in the chamber and exposed to the plasma environment, causing various physical and chemical reactions on the wafer material surface, thereby changing the material surface properties and completing the wafer etching, deposition, or other process.

[0003] In plasma equipment, to achieve maximum efficiency in transmitting RF energy, a matching device must be integrated into the RF system to achieve impedance matching between the RF power supply and the load. Existing impedance matching methods calculate the current input impedance based on the voltage, current, and angle difference signals detected at the input of the impedance matching network. Based on the current input impedance and the standard characteristic impedance of the RF power supply (e.g., 50Ω), the adjustment direction and amount of the variable capacitor in the matching network are calculated. The motor position of the variable capacitor is then adjusted based on this adjustment direction and amount.

[0004] However, existing impedance matching methods are prone to entering a dead zone in processes where plasma ignition is difficult, causing the matcher to freeze and prevent automatic matching. Even in the plasma ignition state, the matching path may pass through the plasma extinguished zone, causing the target matching position to fail. This can lead to repeated ignition, extended matching time, or even failure, resulting in poor ignition and matching stability. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes an impedance matching method and a matching device, which can achieve stable ignition and stable matching of the matching device, thereby improving the stability of the process.

[0006] To achieve the purpose of the present invention, an impedance matching method is provided, which is applied to a matching device, wherein the matching device includes an impedance matching network composed of impedance variable elements; the method includes:

[0007] Determine whether plasma ignition is successful;

[0008] If not, a preset ignition algorithm is used to calculate the adjustment direction and adjustment amount of the variable impedance element, and the value of the variable impedance element is adjusted according to the adjustment direction and the adjustment amount, and then the process returns to the step of determining whether the plasma ignition is successful;

[0009] If yes, calculating the current load impedance based on the detected voltage signal, current signal and angle difference signal at the output end of the impedance matching network, and obtaining the target value of the variable impedance element based on the load impedance;

[0010] Based on the current value of the variable impedance element and the target value, the value of the variable impedance element is adjusted step by step according to a plurality of set step sizes and a set speed corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real part value and the imaginary part value to the real part value and the imaginary part value corresponding to the matching point.

[0011] Optionally, the variable impedance element includes at least one variable capacitor; the target value of the variable impedance element includes a target capacitance value of each variable capacitor;

[0012] The step of adjusting the value of the variable impedance element according to the current value of the variable impedance element and the target value, according to a plurality of set step sizes and a set speed corresponding to each set step size, includes:

[0013] According to the current capacitance of each variable capacitor and the target capacitance, the capacitance of each variable capacitor is adjusted step by step according to the plurality of setting steps corresponding to each variable capacitor and the setting speed corresponding to each setting step.

[0014] Optionally, the impedance matching network is an L-type impedance matching network, wherein the variable impedance element includes a first variable capacitor and a second variable capacitor; the target value of the variable impedance element includes a first target capacitance value of the first variable capacitor and a second target capacitance value of the second variable capacitor;

[0015] The step of adjusting the value of the variable impedance element according to the current value of the variable impedance element and the target value, according to a plurality of set step sizes and a set speed corresponding to each set step size, includes:

[0016] adjusting the capacitance of the first variable capacitor in steps according to the current capacitance of the first variable capacitor and the first target capacitance, at a plurality of first set steps and a first set speed corresponding to each of the first set steps; and adjusting the capacitance of the second variable capacitor in steps according to the current capacitance of the second variable capacitor and the second target capacitance, at a plurality of second set steps and a second set speed corresponding to each of the second set steps;

[0017] Wherein, each time period of the first setting step length and each time period of the second setting step length are performed alternately or synchronously.

[0018] Optionally, each of the first setting step lengths M1 and each of the second setting step lengths M2 satisfies the following relationship:

[0019] M1=(M1a-M1b) / N

[0020] M2=(M2a-M2b) / N

[0021] Among them, M1a is the motor position corresponding to the current capacitance of the first variable capacitor; M1b is the motor position corresponding to the target capacitance of the first variable capacitor; M2a is the motor position corresponding to the current capacitance of the second variable capacitor; M2b is the motor position corresponding to the target capacitance of the second variable capacitor; N is the set number of steps.

[0022] Optionally, each of the first setting step lengths M1 and each of the second setting step lengths M2 satisfies the following relationship:

[0023] M1=M1a-M1a'

[0024] M2=M2a-M2a'

[0025] Wherein, M1a and M1a' are respectively the two motor positions corresponding to the capacitance of the first variable capacitor before and after each change of the real part value of the load impedance by the first unit adjustment amount, the first unit adjustment amount is the ratio of the real part difference to the set number of steps, and the real part difference is the difference between the current real part value of the load impedance and the real part value corresponding to the matching point; M2a and M2a' are respectively the two motor positions corresponding to the capacitance of the second variable capacitor before and after each change of the imaginary part value of the load impedance by the second unit adjustment amount, the second unit adjustment amount is the ratio of the imaginary part difference to the set number of steps, and the imaginary part difference is the difference between the current imaginary part value of the load impedance and the imaginary part value corresponding to the matching point;

[0026] The first setting speed S1′ corresponding to each first setting step M1 and the second setting speed S2′ corresponding to each second setting step M2 both satisfy the following relationship:

[0027] S1'=S1×k1

[0028] S2'=S2×k2

[0029] Among them, S1 is the first setting speed corresponding to the previous first setting step; k1 is the first adjustment coefficient corresponding to each first setting step; S2 is the second setting speed corresponding to the previous second setting step; k2 is the second adjustment coefficient corresponding to each second setting step.

[0030] Optionally, each of the first adjustment coefficients k1 and each of the second adjustment coefficients k2 satisfies the following relationship:

[0031]

[0032]

[0033] Among them, M1a is the motor position corresponding to the current capacitance of the first variable capacitor; M1b is the motor position corresponding to the target capacitance of the first variable capacitor; M2a is the motor position corresponding to the current capacitance of the second variable capacitor; M2b is the motor position corresponding to the target capacitance of the second variable capacitor; N is the set number of steps.

[0034] Optionally, the step of using a preset starting algorithm to calculate and obtain an adjustment direction and an adjustment amount of an impedance variable element in a matching network includes:

[0035] Calculating the adjustment direction and adjustment amount of the variable impedance element based on the input impedance calculated before ignition and the standard characteristic impedance of the RF power supply, and adjusting the value of the variable impedance element based on the adjustment direction and adjustment amount; or

[0036] According to the preset chamber load voltage, the adjustment direction and adjustment amount of the variable impedance element are obtained, and according to the adjustment direction and adjustment amount, the value of the variable impedance element is adjusted.

[0037] Optionally, obtaining a target value of the variable impedance element according to the load impedance includes:

[0038] According to the calculated load impedance and the pre-stored correspondence between the load impedance and the target value of the variable impedance element, the target value of the variable impedance element corresponding to the calculated load impedance is obtained by querying.

[0039] Optionally, after the step of adjusting the value of the variable impedance element in steps according to the current value of the variable impedance element and the target value according to a plurality of set steps and a set speed corresponding to each set step, the method further includes:

[0040] Determine whether the plasma is extinguished;

[0041] If so, the process returns to the step of using the preset starting algorithm to calculate and obtain the adjustment direction and adjustment amount of the variable impedance element in the matching network.

[0042] Optionally, after the step of adjusting the value of the variable impedance element in steps according to the current value of the variable impedance element and the target value according to a plurality of set steps and a set speed corresponding to each set step, the method further includes:

[0043] Determine whether impedance matching is achieved;

[0044] If not, the current input impedance is calculated based on the detected voltage signal, current signal and angle difference signal at the input end of the impedance matching network, and the adjustment direction and adjustment amount of the variable impedance element are calculated based on the current input impedance and the standard characteristic impedance of the RF power supply. The value of the variable impedance element is adjusted according to the adjustment direction and adjustment amount, and the process returns to the step of determining whether impedance matching is achieved.

[0045] Optionally, determining whether impedance matching is achieved includes:

[0046] Determine whether the impedance matching parameter is less than a preset threshold;

[0047] If so, it is determined that impedance matching is achieved;

[0048] If not, it is determined that impedance matching is not achieved.

[0049] Optionally, determining whether the plasma ignition is successful includes:

[0050] According to the detected ignition parameter value, calculating whether the difference between the ignition parameter value detected at the next moment and the ignition parameter value detected at the previous moment is greater than a preset ignition parameter threshold;

[0051] If so, it is determined that the plasma ignition is successful;

[0052] If not, it is determined that the plasma ignition was unsuccessful.

[0053] As another technical solution, the present invention further provides a matching device, comprising an output-end signal acquisition unit, a control unit, and an impedance matching network composed of impedance matching elements, wherein the output-end signal acquisition unit is used to detect a voltage signal, a current signal, and an angle difference signal at the output end of the impedance matching network;

[0054] The control unit is used to determine whether the plasma ignition is successful; if not, the control unit calculates the adjustment direction and adjustment amount of the variable impedance element using a preset ignition algorithm, adjusts the value of the variable impedance element according to the adjustment direction and the adjustment amount, and then returns to the step of determining whether the plasma ignition is successful; if so, the control unit calculates the load impedance based on the voltage signal, current signal, and angle difference signal at the output end of the impedance matching network detected by the output end signal acquisition unit, and obtains the target value of the variable impedance element based on the load impedance; then, based on the current value of the variable impedance element and the target value, the control unit adjusts the value of the variable impedance element step by step according to multiple set step sizes and a set speed corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real part value and imaginary part value to the real part value and imaginary part value corresponding to the matching point.

[0055] Optionally, the impedance matching network is an L-type impedance matching network, wherein the variable impedance element includes a first variable capacitor and a second variable capacitor; the target value of the variable impedance element includes a first target capacitance value of the first variable capacitor and a second target capacitance value of the second variable capacitor;

[0056] The control unit is further configured to:

[0057] adjusting the capacitance of the first variable capacitor in steps according to the current capacitance of the first variable capacitor and the first target capacitance, at a first set step length and a first set speed corresponding to each first set step length; and adjusting the capacitance of the second variable capacitor in steps according to the current capacitance of the second variable capacitor and the second target capacitance, at a second set step length and a second set speed corresponding to each second set step length;

[0058] Wherein, each time period of the first setting step length and each time period of the second setting step length are performed alternately or synchronously.

[0059] The present invention has the following beneficial effects:

[0060] In the impedance matching method and matching device provided by the present invention, when plasma ignition fails, the ignition process is entered. A preset ignition algorithm is used to calculate the adjustment direction and adjustment amount of the variable impedance element in the impedance matching network. The value of the variable impedance element is adjusted based on the adjustment direction and adjustment amount. The process then returns to the step of determining whether plasma ignition is successful. This allows plasma ignition to be achieved, avoiding the situation where the matching device freezes due to entering a matching dead zone. Furthermore, after successful plasma ignition, the matching path calculation process is entered. The current load impedance is calculated to obtain a target value for the variable impedance element. Based on the current and target values ​​of the variable impedance element, the value of the variable impedance element is adjusted step by step according to multiple set steps and set speeds corresponding to each set step, so as to simultaneously adjust the load impedance from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point. This prevents impedance overshoot, which can cause repeated ignition and extended matching time, or the problem of the matching path passing through a quenching region, leading to quenching. This allows for stable ignition and matching of the matching device, thereby improving process stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic diagram of the structure of a typical ICP device;

[0062] Figure 2 is an equivalent circuit diagram of an existing matching device;

[0063] Figure 3 A flowchart of an existing impedance matching method is provided;

[0064] Figure 4 This is a schematic diagram of an existing matching path;

[0065] Figure 5 A flowchart of an impedance matching method according to a first embodiment of the present invention;

[0066] Figure 6 An equivalent circuit diagram of a matching device provided by the first embodiment of the present invention;

[0067] Figure 7 An equivalent circuit diagram of another matching device provided by the first embodiment of the present invention;

[0068] Figure 8 A motor operation path diagram corresponding to a step-by-step adjustment method adopted in the first embodiment of the present invention;

[0069] Figure 9 A diagram showing the change path of the real and imaginary parts of the load impedance corresponding to another step-by-step adjustment method adopted in the first embodiment of the present invention;

[0070] Figure 10A flowchart of an impedance matching method provided in accordance with a second embodiment of the present invention;

[0071] Figure 11 A schematic diagram of a matching path corresponding to the impedance matching method provided in the second embodiment of the present invention. DETAILED DESCRIPTION

[0072] To enable those skilled in the art to better understand the technical solution of the present invention, the impedance matching method and the matching device provided by the present invention are described in detail below with reference to the accompanying drawings.

[0073] Figure 1 This is a typical ICP device schematic diagram. Figure 1 The inductively coupled plasma (ICP) device includes a process chamber 1, in which a susceptor 4 is provided for supporting a wafer 5; the susceptor 4 is electrically connected to a bias power supply 2 through a lower matcher 3; a dielectric window 7 is provided at the top of the process chamber 1, and a coil 8 is provided above the dielectric window 7, and the coil 8 is electrically connected to a radio frequency power supply 9 through an upper matcher 10; the radio frequency power supply 9 loads radio frequency power into the process chamber 1 through the coil 8 to excite the process gas in the process chamber 1 to form a plasma 6, and the plasma 6 acts on the wafer 5 to meet the process requirements.

[0074] Figure 2 This is an equivalent circuit diagram of an existing matching device. Figure 2 The matching device includes an input sensor 11, a control unit 12, an execution unit 13 and a matching circuit unit 14, wherein the input sensor 11 is used to detect the voltage signal, current signal and angle difference signal at the input end of the matching circuit unit 14 (i.e., the impedance matching network) and send them to the control unit 12; the control unit 12 is used to calculate the current input impedance (i.e., the input end impedance of the impedance matching network), and calculate the adjustment direction and adjustment amount of the variable capacitor in the matching circuit unit 14 (i.e., the impedance matching network) based on the current input impedance and the standard characteristic impedance of the RF power supply (e.g., 50Ω), and control the execution unit 13 to adjust the motor position of the variable capacitor based on the adjustment direction and adjustment amount. Specifically, taking the impedance matching network as an L-type impedance matching network as an example, the matching circuit unit 14 includes a first variable capacitor C1 and a second variable capacitor C2; the execution unit 13 includes two motors for adjusting the capacitance of the first variable capacitor C1 and the second variable capacitor C2 respectively, and the motors are, for example, stepper motors. Since there is a one-to-one correspondence between the motor position and the capacitance of the variable capacitor, the capacitance of the variable capacitor can be adjusted to the target value by adjusting the motor position to achieve impedance matching.

[0075] Figure 3This is a flowchart of an existing impedance matching method. Figure 3 The impedance matching method, after the RF power supply is turned on, includes the following steps:

[0076] Calculating the current input impedance based on the detected voltage signal, current signal and angle difference signal at the input end of the impedance matching network;

[0077] Determine whether the modulus of the current input impedance is equal to 50Ω (i.e., the standard characteristic impedance); if not, determine whether the modulus of the current input impedance is greater than 50Ω or less than 50Ω; if greater than 50Ω, increase the capacitance of the second variable capacitor C2; if less than 50Ω, decrease the capacitance of the second variable capacitor C2;

[0078] If so, determine whether the phase of the current input impedance is equal to 0; if not, determine whether the phase of the current input impedance is greater than 0 or less than 0; if less than 0, increase the capacitance of the first variable capacitor C1; if greater than 0, reduce the capacitance of the first variable capacitor C1; if equal to 0, determine whether the plasma process is completed; if not, return to the above step of calculating the current input impedance; if yes, the process ends.

[0079] However, under process conditions where plasma ignition is difficult (for example, in an ICP device with a chamber volume of 10L, a chamber pressure of 100mT, oxygen as the process gas at a gas flow rate of 200sccm, and an RF power of 500W applied to the upper electrode), the impedance matching method can easily enter a dead zone, causing the matching device to freeze and prevent automatic matching. Furthermore, the matching algorithm can only determine the adjustment direction (i.e., increasing or decreasing the capacitance), but not the adjustment amount (i.e., the change in capacitance). This results in poor control accuracy and is prone to overshoot, which can cause repeated capacitance adjustments, resulting in prolonged matching time and even loss of control.

[0080] In addition, even in the plasma ignition state, the original target matching position may fail due to the matching path passing through the plasma extinguished zone, resulting in repeated ignition and matching time extension or failure, and poor ignition stability and matching stability. Figure 4 This is a schematic diagram of an existing matching path. Figure 4 As shown in the figure, after the RF power is turned on, the load impedance changes during the impedance matching process of the matching device. Figure 4The position change in the matching path is represented by the figure, that is, the matching path from position P1 to position P6, wherein the plasma is struck after reaching position P2, but in the process from position P3 to position P4, it is extinguished due to passing through the extinguishing area, resulting in failure of the original target matching position when subsequently reaching position P6 from position P5, resulting in repeated ignition and extended or failed matching time, and poor ignition stability and matching stability.

[0081] First embodiment

[0082] To solve the above problem, please refer to Figure 5 A first embodiment of the present invention provides an impedance matching method, which is applied to a matching device, wherein the matching device includes an impedance matching network composed of variable impedance elements. The method includes the following steps:

[0083] S1, determine whether the plasma ignition is successful; if not, proceed to step S2; if so, proceed to step S3;

[0084] S2. Calculate the adjustment direction and adjustment amount of the variable impedance element using a preset starting algorithm, and adjust the value of the variable impedance element according to the adjustment direction and the adjustment amount, and then return to step S1 above;

[0085] S3. Calculate the current load impedance (i.e., the output impedance of the impedance matching network) based on the detected voltage signal, current signal, and angle difference signal at the output end of the impedance matching network, and obtain a target value of the variable impedance element based on the load impedance;

[0086] S4. Based on the current value of the variable impedance element and the target value, the value of the variable impedance element is adjusted step by step according to a plurality of set step sizes and a set speed corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real part value and the imaginary part value to the real part value and the imaginary part value corresponding to the matching point.

[0087] The impedance matching method provided in the first embodiment of the present invention, by adding steps S1 and S2, can monitor whether ignition has occurred. If ignition fails, the value of the variable impedance element is readjusted, and steps S1 and S2 are repeated until plasma ignition is successful. This avoids the situation where the matching device freezes due to a matching dead zone.

[0088] In step S2, the current value of the variable impedance element is, for example, the current capacitance of a variable capacitor, or the current position of a rotor of the variable capacitor. This current capacitance or current position can be detected and obtained by the execution unit 13. The adjustment amount of the variable impedance element is the difference between the current value of the variable impedance element and the target value. If the variable impedance element is a variable capacitor, the adjustment amount is the difference (absolute value) between the current capacitance of the variable capacitor and the target capacitance, or the distance between the current position and the target position of the rotor of the variable capacitor.

[0089] Figure 6 This is an equivalent circuit diagram of the matching device provided by the first embodiment of the present invention. Figure 6 , the matcher is in Figure 2 On the basis of the matcher in, an output terminal signal acquisition unit 15 is added to detect the voltage signal, current signal and angle difference signal at the output terminal of the matching circuit unit 14 (i.e., the impedance matching network). Optionally, depending on the type of the impedance matching network, the impedance variable element in the matching circuit unit 14 (i.e., the impedance matching network) includes at least one variable capacitor. For example, one variable capacitor, two variable capacitors or more than three variable capacitors. The variable capacitor is, for example, a vacuum variable capacitor or a ceramic capacitor group, etc. Of course, in practical applications, the above-mentioned impedance variable element may also include an inductor, or a combination of an inductor and a capacitor, and the inductor is, for example, an air inductor, a magnetic core inductor or a winding inductor, etc. Optionally, the execution unit 13 includes a motor for adjusting the value of the variable impedance element (such as the capacitance of the variable capacitor), and the motor is, for example, a stepper motor, a servo motor, etc.; the execution unit 13 may also include an electronic switch for adjusting the value of the variable impedance element (such as the capacitance of the variable capacitor), and the electronic switch is, for example, a relay, a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) or an Insulated Gate Bipolar Transistor (IGBT), etc.

[0090] In step S3, the current load impedance can be calculated based on the detected voltage signal, current signal and angle difference signal at the output end of the matching circuit unit 14 (i.e., the impedance matching network). Specifically, the current load impedance satisfies the following relationship:

[0091]

[0092] Wherein, Zout is the load impedance; R is the real part of the load impedance; X is the imaginary part of the load impedance; V is the voltage signal; I is the current signal; θ is the angle difference signal between the voltage signal and the current signal.

[0093] In step S3, a target value for the variable impedance element is obtained based on the load impedance. This target value refers to the value of the variable impedance element that will achieve impedance matching. If the variable impedance element is a variable capacitor, the target value is the target capacitance of the variable capacitor when achieving impedance matching; alternatively, the target value may be the target position of the variable capacitor's rotor when achieving impedance matching.

[0094] There are many ways to obtain the target value of the variable impedance element based on the load impedance. For example, a correspondence table between the load impedance and the value of the variable impedance element can be pre-stored. After the load impedance is calculated, the target value of the variable impedance element corresponding to the current load impedance can be found from the pre-stored correspondence table between the load impedance and the target value of the variable impedance element (for example, Table 1 below) by looking up the table addressing method. In this way, the matching position can be quickly reached, thereby shortening the matching time and achieving fast matching. Optionally, as Figure 7 As shown, the matcher Figure 6 On the basis of the matcher in FIG, a storage unit 16 is added for storing the above correspondence table. In addition, the values ​​in the correspondence table stored in the storage unit 16 can also be calibrated by an instrument such as a network analyzer.

[0095] Table 1. Correspondence between load impedance and target value of variable impedance element.

[0096]

[0097]

[0098] In step S4, the value of the variable impedance element is adjusted step by step based on the current value and target value of the variable impedance element, according to multiple set step sizes and set speeds corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point. In other words, the load impedance is moved from the current position to the matching point in a stepwise manner, with the distance of each step being the set step size, and different set step sizes can be the same or different. Each set step size corresponds to a set speed, and different set step sizes can correspond to the same or different set speeds. By controlling the set step size and set speed, the load impedance is simultaneously adjusted from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point. This prevents impedance overshoot, which can cause repeated ignition and extended matching time, or prevents extinguishing caused by the matching path passing through the extinguishing region. This allows for stable ignition and matching of the matching device, thereby improving process stability.

[0099] Before executing step S4, taking the impedance variable element as a variable capacitor as an example, the adjustment speed of the motor position (i.e., the moving speed of the movable plate of the variable capacitor) is the default speed. However, if the capacitance of the variable capacitor is still adjusted at the default speed at the same speed during the execution of step S4, the impedance overshoot or the matching path passing through the extinguishing area may cause the problem of extinguishing. This is because the capacitance of the variable capacitor is always adjusted continuously at the same default speed, which may cause the load impedance to change discontinuously, easily causing mutations, thereby causing extinguishing. At the same time, taking the impedance matching network as an L-type impedance matching network as an example, when the ratio (i.e., the moving speed) of the moving distance (the distance between the current position and the matching position) of the two motors used to adjust the capacitance of the first variable capacitor C1 and the second variable capacitor C2 respectively is not equal, there will inevitably be one motor arriving first and the other motor not arriving, which makes the matcher make a judgment that the impedance matching has not yet been achieved and issue an instruction to continue to require the motor to run. When the latter motor arrives, the former motor has exceeded the matching position and needs to be called back, resulting in the problem of continuous oscillation and overshoot of the two motors. In this regard, in the above step S4, by adjusting the value of the variable impedance element in steps according to multiple set step sizes and the set speed corresponding to each set step size, the load impedance can be adjusted from the current real part value and imaginary part value to the real part value and imaginary part value corresponding to the matching point at the same time, that is, the two motors can reach the matching position at almost the same time, thereby avoiding the problem of continuous oscillation and overshoot of the two motors.

[0100] It should be noted that, in practical applications, depending on the type of the impedance matching network, the variable impedance element may include at least one variable capacitor. In this case, step S4 includes:

[0101] According to the current capacitance and target capacitance of each variable capacitor, the capacitance of each variable capacitor is adjusted step by step according to a plurality of setting steps corresponding to each variable capacitor and a setting speed corresponding to each setting step.

[0102] By adjusting the capacitance of each variable capacitor in the above-mentioned step-by-step adjustment method, it is possible to prevent impedance overshoot, which causes repeated ignition and extended matching time, or the problem of extinguishing the ignition due to the matching path passing through the extinguishing area, thereby achieving stable ignition and stable matching of the matcher, thereby improving the stability of the process.

[0103] It should be noted that, in practical applications, other methods may be used to adjust the value of the variable impedance element. For example, the capacitance of at least one variable capacitor may be adjusted by an electronic switch. In this case, the capacitance of each variable capacitor may also be adjusted by the above-mentioned step-by-step adjustment method, as long as the load impedance is adjusted simultaneously from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point.

[0104] There are many ways to adjust the steps, for example: Figure 6 and Figure 7 As shown, the impedance matching network is an L-type impedance matching network, and the matching circuit unit 14 includes a first variable capacitor C1 and a second variable capacitor C2. The target value of the variable impedance element includes a first target capacitance value of the first variable capacitor C1 and a second target capacitance value of the second variable capacitor C2. The capacitance value of the first variable capacitor C1 corresponds to the real part value of the load impedance; the capacitance value of the second variable capacitor C2 corresponds to the imaginary part value of the load impedance. In this case, step S4 includes:

[0105] The capacitance of the first variable capacitor C1 is adjusted step by step based on the current capacitance of the first variable capacitor C1 and the first target capacitance, according to a plurality of first set steps and a first set speed corresponding to each first set step. Simultaneously, the capacitance of the second variable capacitor C2 is adjusted step by step based on the current capacitance of the second variable capacitor C2 and the second target capacitance, according to a plurality of second set steps and a second set speed corresponding to each second set step. The time period of each first set step is alternated with the time period of each second set step. That is, when the position of the motor for adjusting the capacitance of the first variable capacitor C1 moves by each first set step, the position of the motor for adjusting the capacitance of the second variable capacitor C2 does not move. Conversely, when the position of the motor for adjusting the capacitance of the second variable capacitor C2 moves by each first set step, the position of the motor for adjusting the capacitance of the first variable capacitor C1 does not move. In this way, the two motors can reach the matching position substantially at the same time, thereby avoiding the problem of continuous oscillation and overshoot of the two motors.

[0106] Of course, in actual applications, the time period of each first setting step and the time period of each second setting step can also be carried out synchronously, that is, when the motor position for adjusting the capacitance of the first variable capacitor C1 moves each first setting step, the motor position for adjusting the capacitance of the second variable capacitor C2 also moves each second setting step, and each first setting step needs to run according to the first setting speed, and each second setting step needs to run according to the second setting speed to ensure that the motor positions of the capacitances of the first variable capacitor C1 and the second variable capacitor C2 reach the matching position at the same time.

[0107] In some optional embodiments, each first setting step length M1 and each second setting step length M2 satisfy the following relationship:

[0108] M1=(M1a-M1b) / N

[0109] M2=(M2a-M2b) / N

[0110] Among them, M1a is the motor position corresponding to the current capacitance of the first variable capacitor C1; M1b is the motor position corresponding to the target capacitance of the first variable capacitor C1; M2a is the motor position corresponding to the current capacitance of the second variable capacitor C2; M2b is the motor position corresponding to the target capacitance of the second variable capacitor C2; N is the set number of steps.

[0111] That is to say, the distance between the motor position corresponding to the current capacitance value and the motor position corresponding to the target capacitance value is divided into N parts, and each set step size is the ratio of this distance to N. Figure 8 As shown, the time duration for moving from motor position M1a to motor position M1b is divided into 100 time periods, namely, 0-t1, t1-t2, ..., t98-t99, t99-t100, wherein the setting step length corresponding to the 0-t1 time period is the first setting step length M1 mentioned above, and the motor position remains unchanged during the t1-t2 time period. Similarly, the time periods of the first setting step length M1 are alternated with the time periods in which the motor does not move, until 100 time periods are completed. Similarly, the time duration for moving from motor position M2a to motor position M2b is divided into 100 time periods, namely, 0-t1, t1-t2, ..., t98-t99, t99-t100, wherein the motor position remains unchanged during the 0-t1 time period, and the setting step length corresponding to the t1-t2 time period is the second setting step length M2 mentioned above. Similarly, the time periods in which the motor does not move are alternated with the time periods of the second setting step length M2, until 100 time periods are completed. In this way, the two motors can reach the matching position at substantially the same time, thereby avoiding the problem of continuous oscillation and overshoot of the two motors. It is easy to understand that the number of time periods divided into the time period for moving from motor position M1a to motor position M1b corresponds to the set number of steps N. For example, if the set number of steps N is 50, the number of time periods is 100.

[0112] In the above-mentioned step-by-step adjustment method, multiple setting step sizes are the same, and the setting speeds corresponding to the multiple setting step sizes are the same. However, the embodiments of the present invention are not limited to this. In actual applications, the capacitance of the first variable capacitor C1 and the capacitance of the second variable capacitor C2 can also be adjusted simultaneously, and before each setting step period, the setting speed corresponding to the setting step needs to be calculated using the above-mentioned relationship, and then executed according to the calculated setting speed during each setting step period, so as to achieve the simultaneous adjustment of the load impedance from the current real part value and imaginary part value to the real part value and imaginary part value corresponding to the matching point, so as to ensure that the two capacitors reach the matching point at the same time. Specifically, in other optional embodiments, the capacitance of the above-mentioned first variable capacitor C1 corresponds to the real part value of the load impedance; the capacitance of the second variable capacitor C2 corresponds to the imaginary part value of the load impedance. As Figure 9 As shown, each first setting step length M1 and each second setting step length M2 satisfy the following relationship:

[0113] M1=M1a-M1a'

[0114] M2=M2a-M2a'

[0115] Among them, M1a and M1a' are respectively the two motor positions (i.e., the two motor positions corresponding to Ra and Ra') corresponding to the capacitance of the first variable capacitor C1 before and after the real part value of the load impedance changes by the first unit adjustment amount △R (equal to the difference between Ra and Ra'), and the first unit adjustment amount △R is the ratio of the real part difference to the set step number, and the real part difference is the difference between the current real part value Ra of the load impedance and the real part value Rb corresponding to the matching point; M2a and M2a' are respectively the two motor positions (i.e., the two motor positions corresponding to Xa and Xa') corresponding to the capacitance of the second variable capacitor C2 before and after the imaginary part value of the load impedance changes by the second unit adjustment amount △X (equal to the difference between Xa and Xa'), and the second unit adjustment amount △X is the ratio of the imaginary part difference to the set step number, and the imaginary part difference is the difference between the current imaginary part value Xa of the load impedance and the imaginary part value Xb corresponding to the matching point.

[0116] That is, the real part difference between the current real part value Ra of the load impedance and the real part value Rb corresponding to the matching point is evenly divided into N (set number of steps), and each set step is the motor position change corresponding to the ratio of the real part difference to N (the first unit adjustment amount). Figure 9As shown, the time duration from the motor position M1a corresponding to the current real value Ra to the motor position M1b corresponding to the real value Rb corresponding to the matching point is divided into 100 time periods, namely, 0-t1, t1-t2, ..., t98-t99, t99-t100, wherein the motor position in the 0-t1 time period remains unchanged, and the set step length corresponding to the first unit adjustment amount △R in the t1-t2 time period is the above-mentioned first set step length M1, and so on, the time period of the first set step length M1 is alternated with the time period in which the motor does not move, until 100 time periods are completed. Similarly, the time duration from the motor position M2a corresponding to the current imaginary value Xa to the motor position M2b corresponding to the imaginary value Xb corresponding to the matching point is divided into 100 time periods, namely, 0-t1, t1-t2, ..., t98-t99, t99-t100, wherein the set step length corresponding to the second unit adjustment amount △X corresponding to the 0-t1 time period is the above-mentioned second set step length M2, the motor position remains unchanged during the t1-t2 time period, and so on. The time periods of the second set step length M2 are alternated with the time periods in which the motor does not move until 100 time periods are completed. In this way, the two motors can reach the matching position at almost the same time, that is, the load impedance is adjusted from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point at the same time, thereby avoiding the problem of continuous oscillation and overshoot of the two motors. It is easy to understand that the number of time periods divided into the time duration from the motor position M1a to the motor position M1b has a corresponding relationship with the set number of steps N. For example, if the set number of steps N is 50, the number of time periods is 100. Of course, in practical applications, the time period of each first setting step length M1 and the time period of each second setting step length M2 can also be performed synchronously.

[0117] On this basis, the first set speed S1' corresponding to each first set step M1 and the second set speed S2' corresponding to each second set step M2 both satisfy the following relationship:

[0118] S1'=S1×k1

[0119] S2'=S2×k2

[0120] Among them, S1 is the first set speed corresponding to the previous first set step; k1 is the first adjustment coefficient corresponding to each first set step; S2 is the second set speed corresponding to the previous second set step; k2 is the second adjustment coefficient corresponding to each second set step.

[0121] In this way, before each set step period, the set speed corresponding to the set step needs to be calculated using the above relationship to achieve the simultaneous adjustment of the load impedance from the current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point.

[0122] There are many ways to set each first adjustment coefficient k1 and each second adjustment coefficient k2. For example, both satisfy the following relationship:

[0123]

[0124]

[0125] Among them, M1a is the motor position corresponding to the current capacitance of the first variable capacitor C1; M1b is the motor position corresponding to the target capacitance of the first variable capacitor C1; M2a is the motor position corresponding to the current capacitance of the second variable capacitor C2; M2b is the motor position corresponding to the target capacitance of the second variable capacitor C2; N is the set number of steps.

[0126] The present invention has no particular limitation on the starting algorithm in step S2. In some optional embodiments, in step S2, a preset starting algorithm is used to calculate and obtain the adjustment direction and adjustment amount of the variable impedance element in the impedance matching network, including:

[0127] Based on the input impedance calculated before ignition and the standard characteristic impedance of the RF power supply, the adjustment direction and adjustment amount of the variable impedance element are calculated, and the value of the variable impedance element is adjusted based on the adjustment direction and adjustment amount. In other words, if ignition is not successful, the impedance is adjusted to the matching position obtained before ignition. The above-mentioned ignition algorithm may specifically include the following steps:

[0128] Calculate the current input impedance based on the detected voltage signal, current signal and angle difference signal at the input end of the impedance matching network;

[0129] Determine whether the modulus of the current input impedance is equal to 50Ω (i.e., the standard characteristic impedance); if not, determine whether the modulus of the current input impedance is greater than 50Ω or less than 50Ω; if greater than 50Ω, increase the capacitance of the second variable capacitor C2; if less than 50Ω, reduce the capacitance of the second variable capacitor C2; if so, determine whether the phase of the current input impedance is equal to 0; if not equal to 0, determine whether the phase of the current input impedance is greater than 0 or less than 0; if less than 0, increase the capacitance of the first variable capacitor C1; if greater than 0, reduce the capacitance of the first variable capacitor C1.

[0130] Alternatively, another ignition algorithm determines the adjustment direction and amount of the variable impedance element based on a preset chamber load voltage, and adjusts the value of the variable impedance element based on the adjustment direction and amount. The chamber load voltage can be set empirically; specifically, the value of the variable impedance element can be adjusted by appropriately increasing the chamber load voltage.

[0131] Second embodiment

[0132] See also Figure 10 The impedance matching method provided in the second embodiment of the present invention is an improvement based on the first embodiment. Specifically, after the above step S4, it further includes:

[0133] S5: Determine whether the plasma is extinguished; if so, return to step S2. With step S5, the preset ignition algorithm can be used again to adjust the value of the variable impedance element when the plasma is extinguished.

[0134] In some optional embodiments, if it is determined in step S5 that the plasma has not been extinguished, the following steps are performed:

[0135] S6, determine whether impedance matching is achieved; if not, proceed to step S7; if so, proceed to step S8;

[0136] S7. Calculate the current input impedance based on the detected voltage signal, current signal, and angle difference signal at the input end of the impedance matching network. Calculate the adjustment direction and amount of the variable impedance element based on the current input impedance and the standard characteristic impedance of the RF power supply (e.g., 50Ω). Adjust the value of the variable impedance element based on the adjustment direction and amount, and return to step S6.

[0137] With the aid of step S7, when impedance matching is not achieved, the value of the variable impedance element can be further fine-tuned based on the rapid arrival at the matching position in step S4 to more accurately reach the matching position. The matching algorithm of step S7 may include, for example:

[0138] Calculate the current input impedance based on the detected voltage signal, current signal and angle difference signal at the input end of the impedance matching network;

[0139] Determine whether the modulus of the current input impedance is equal to 50Ω (i.e., the standard characteristic impedance); if not, determine whether the modulus of the current input impedance is greater than 50Ω or less than 50Ω; if greater than 50Ω, increase the capacitance of the second variable capacitor C2; if less than 50Ω, reduce the capacitance of the second variable capacitor C2; if so, determine whether the phase of the current input impedance is equal to 0; if not equal to 0, determine whether the phase of the current input impedance is greater than 0 or less than 0; if less than 0, increase the capacitance of the first variable capacitor C1; if greater than 0, reduce the capacitance of the first variable capacitor C1.

[0140] Specifically, the amount of fine-tuning of the capacitance of the first variable capacitor C1 is proportional to the modulus difference between the input impedance and the standard characteristic impedance, for example, equal to the product of the modulus difference and the modulus coefficient. Similarly, the amount of fine-tuning of the capacitance of the second variable capacitor C2 is proportional to the phase difference between the input impedance and the standard characteristic impedance, for example, equal to the product of the phase difference and the phase coefficient. The modulus coefficient and phase coefficient can be freely set according to specific circumstances.

[0141] In the above step S6, there may be multiple ways to determine whether impedance matching is achieved. For example, in some optional embodiments, determining whether impedance matching is achieved includes:

[0142] Determine whether the impedance matching parameter is less than a preset threshold;

[0143] If so, it is determined that impedance matching is achieved;

[0144] If not, it is determined that impedance matching is not achieved.

[0145] The above impedance matching parameters include, for example, physical parameters related to impedance matching such as voltage standing wave ratio, reflection coefficient, etc. Taking the voltage standing wave ratio as an example, determining whether impedance matching is achieved includes:

[0146] Determine whether the voltage standing wave ratio (VSWR) is less than a preset VSWR threshold (e.g., 1.2);

[0147] If so, it is determined that impedance matching is achieved;

[0148] If not, it is determined that impedance matching is not achieved.

[0149] In the above step S1, there are multiple ways to determine whether the plasma ignition is successful. For example, in some optional embodiments, determining whether the plasma ignition is successful includes:

[0150] According to the detected ignition parameter value, calculating whether the difference between the ignition parameter value detected at the next moment and the ignition parameter value detected at the previous moment is greater than a preset ignition parameter threshold;

[0151] If so, it is determined that the plasma ignition is successful;

[0152] If not, it is determined that the plasma ignition was unsuccessful.

[0153] The ignition parameter value includes, for example, a physical parameter related to ignition, such as a current value or an impedance value at the input end of an impedance matching network. Taking the ignition parameter value as the current value at the input end of an impedance matching network as an example, determining whether the plasma ignition is successful includes:

[0154] Calculate, based on the detected current signal at the input end of the impedance matching network, whether the difference between the current value detected at the next moment and the current value detected at the previous moment is greater than a preset current threshold (e.g., 10);

[0155] If so, it is determined that the plasma ignition is successful;

[0156] If not, it is determined that the plasma ignition was unsuccessful.

[0157] like Figure 11 As shown in FIG. 1 , a matching path is obtained by using the impedance matching method provided by an embodiment of the present invention. During the impedance matching process of the matching device, the change of the load impedance is determined by Figure 11 , i.e., the matching path from position P1' to position P5'. After reaching position P2', the plasma is ignited, and impedance matching is performed in a step-by-step manner through steps S3 and S4 to achieve the transition from position P3' to position P4'. During this process, no extinguishing occurs. Then, fine-tuning is performed through steps S6 and S7 to achieve the transition from position P4' to position P5', ultimately achieving stable ignition and stable matching of the matching device.

[0158] As another technical solution, an embodiment of the present invention further provides a matching device, which includes an output terminal signal acquisition unit, a control unit and a matching circuit unit 14 (i.e., an impedance matching network), wherein the output terminal signal acquisition unit is used to detect the voltage signal, current signal and angle difference signal at the output terminal of the matching device; the output terminal signal acquisition unit and the matching circuit unit 14 are connected. Figure 6 and Figure 7 The output signal acquisition unit 15 shown in FIG. 1 has the same function.

[0159] The control unit is used to determine whether the plasma ignition is successful; if not, a preset ignition algorithm is used to calculate the adjustment direction and adjustment amount of the variable impedance element, and according to the adjustment direction and adjustment amount, the value of the variable impedance element is adjusted, and then the process returns to the above step of determining whether the plasma ignition is successful; if so, the load impedance is calculated based on the voltage signal, current signal and angle difference signal at the output end of the impedance matching network detected by the output end signal acquisition unit, and the target value of the variable impedance element is obtained based on the load impedance; then, according to the current value and target value of the variable impedance element, the value of the variable impedance element is adjusted step by step according to multiple set step sizes and set speeds corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real part value and imaginary part value to the real part value and imaginary part value corresponding to the matching point.

[0160] In some optional embodiments, the impedance matching network is an L-type impedance matching network, and its function is similar to Figure 6 and Figure 7The matching circuit unit 14 shown in FIG has the same function. The variable impedance element includes a first variable capacitor C1 and a second variable capacitor C2; the target value of the variable impedance element includes a first target capacitance value of the first variable capacitor C1 and a second target capacitance value of the second variable capacitor C2.

[0161] On this basis, the above control unit is also used to:

[0162] The capacitance of the first variable capacitor C1 is adjusted in steps based on the current capacitance of the first variable capacitor C1 and the first target capacitance, according to a first set step length and a first set speed corresponding to each first set step length. Simultaneously, the capacitance of the second variable capacitor C2 is adjusted in steps based on the current capacitance of the second variable capacitor C2 and the second target capacitance, according to a second set step length and a second set speed corresponding to each second set step length. The time period of each first set step length is alternated or synchronized with the time period of each second set step length. In this way, the two motors can reach the matching position substantially at the same time, thereby avoiding the problem of continuous oscillation and overshoot of the two motors.

[0163] Optionally, the matcher provided in the embodiment of the present invention adopts, for example, Figure 6 or Figure 7 The matcher shown in has been described in detail in the previous text and will not be repeated here.

[0164] In summary, the impedance matching method and matching device provided by the present invention enter an ignition process when plasma ignition fails. A preset ignition algorithm is used to calculate the adjustment direction and amount of the variable impedance element. Based on the adjustment direction and amount, the value of the variable impedance element is adjusted. The process then returns to the step of determining whether plasma ignition was successful. This allows plasma ignition to be achieved, avoiding the situation where the matching device freezes due to entering a matching dead zone. Furthermore, after successful plasma ignition, a matching path calculation process is entered. The current load impedance is calculated to obtain a target value for the variable impedance element. Based on the current and target values ​​of the variable impedance element, the value of the variable impedance element is adjusted stepwise according to multiple set steps and set speeds corresponding to each set step, so as to simultaneously adjust the load impedance from its current real and imaginary values ​​to the real and imaginary values ​​corresponding to the matching point. This prevents impedance overshoot, which can cause repeated ignition and extended matching time, or extinguishing due to the matching path passing through an extinguishing zone. This allows for stable ignition and matching of the matching device, thereby improving process stability.

[0165] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An impedance matching method, applied to a matching device, wherein the matching device includes an impedance matching network composed of impedance variable elements; characterized in that: The impedance matching method comprises: Determine whether plasma ignition is successful; If not, a preset ignition algorithm is used to calculate the adjustment direction and adjustment amount of the variable impedance element, and the value of the variable impedance element is adjusted according to the adjustment direction and the adjustment amount, and then the process returns to the step of determining whether the plasma ignition is successful; If yes, calculating the current load impedance based on the detected voltage signal, current signal and angle difference signal at the output end of the impedance matching network, and obtaining the target value of the variable impedance element based on the load impedance; Based on the current value of the variable impedance element and the target value, the value of the variable impedance element is adjusted step by step according to a plurality of set step sizes and a set speed corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real part value and the imaginary part value to the real part value and the imaginary part value corresponding to the matching point.

2. The impedance matching method according to claim 1, wherein: The variable impedance element includes at least one variable capacitor; the target value of the variable impedance element includes the target capacitance value of each variable capacitor; The step of adjusting the value of the variable impedance element according to the current value of the variable impedance element and the target value, according to a plurality of set step sizes and a set speed corresponding to each set step size, includes: According to the current capacitance of each variable capacitor and the target capacitance, the capacitance of each variable capacitor is adjusted step by step according to the plurality of setting steps corresponding to each variable capacitor and the setting speed corresponding to each setting step.

3. The impedance matching method according to claim 2, wherein: The impedance matching network is an L-shaped impedance matching network, wherein the variable impedance element includes a first variable capacitor and a second variable capacitor; the target value of the variable impedance element includes a first target capacitance value of the first variable capacitor and a second target capacitance value of the second variable capacitor; The step of adjusting the value of the variable impedance element according to the current value of the variable impedance element and the target value, according to a plurality of set step sizes and a set speed corresponding to each set step size, includes: adjusting the capacitance of the first variable capacitor in steps according to the current capacitance of the first variable capacitor and the first target capacitance, at a plurality of first set steps and a first set speed corresponding to each of the first set steps; and adjusting the capacitance of the second variable capacitor in steps according to the current capacitance of the second variable capacitor and the second target capacitance, at a plurality of second set steps and a second set speed corresponding to each of the second set steps; Wherein, each time period of the first setting step length and each time period of the second setting step length are performed alternately or synchronously.

4. The impedance matching method according to claim 3, wherein: Each of the first setting step lengths M1 and each of the second setting step lengths M2 satisfies the following relationship: M1=(M1a-M1b) / N M2=(M2a-M2b) / N Among them, M1a is the motor position corresponding to the current capacitance of the first variable capacitor; M1b is the motor position corresponding to the target capacitance of the first variable capacitor; M2a is the motor position corresponding to the current capacitance of the second variable capacitor; M2b is the motor position corresponding to the target capacitance of the second variable capacitor; N is the set number of steps.

5. The impedance matching method according to claim 3, wherein: Each of the first setting step lengths M1 and each of the second setting step lengths M2 satisfies the following relationship: M1=M1a-M1a' M2=M2a-M2a' Wherein, M1a and M1a' are respectively the two motor positions corresponding to the capacitance of the first variable capacitor before and after each change of the real part value of the load impedance by the first unit adjustment amount, the first unit adjustment amount is the ratio of the real part difference to the set number of steps, and the real part difference is the difference between the current real part value of the load impedance and the real part value corresponding to the matching point; M2a and M2a' are respectively the two motor positions corresponding to the capacitance of the second variable capacitor before and after each change of the imaginary part value of the load impedance by the second unit adjustment amount, the second unit adjustment amount is the ratio of the imaginary part difference to the set number of steps, and the imaginary part difference is the difference between the current imaginary part value of the load impedance and the imaginary part value corresponding to the matching point; The first setting speed S1′ corresponding to each first setting step M1 and the second setting speed S2′ corresponding to each second setting step M2 both satisfy the following relationship: S1'=S1×k1 S2'=S2×k2 Among them, S1 is the first setting speed corresponding to the previous first setting step; k1 is the first adjustment coefficient corresponding to each first setting step; S2 is the second setting speed corresponding to the previous second setting step; k2 is the second adjustment coefficient corresponding to each second setting step.

6. The impedance matching method according to claim 5, wherein: Each of the first adjustment coefficients k1 and each of the second adjustment coefficients k2 satisfies the following relationship: Among them, M1a is the motor position corresponding to the current capacitance of the first variable capacitor; M1b is the motor position corresponding to the target capacitance of the first variable capacitor; M2a is the motor position corresponding to the current capacitance of the second variable capacitor; M2b is the motor position corresponding to the target capacitance of the second variable capacitor; N is the set number of steps.

7. The impedance matching method according to any one of claims 1 to 6, characterized in that: The method of using a preset starting algorithm to calculate and obtain the adjustment direction and adjustment amount of the variable impedance element in the matching network includes: According to the input impedance calculated before ignition and the standard characteristic impedance of the RF power supply, the adjustment direction and adjustment amount of the variable impedance element are calculated, and the value of the variable impedance element is adjusted according to the adjustment direction and adjustment amount; or, The adjustment direction and adjustment amount of the variable impedance element are obtained according to the preset chamber load voltage, and the value of the variable impedance element is adjusted according to the adjustment direction and adjustment amount.

8. The impedance matching method according to any one of claims 1 to 6, characterized in that: Obtaining a target value of the variable impedance element according to the load impedance includes: According to the calculated load impedance and the pre-stored correspondence between the load impedance and the target value of the variable impedance element, the target value of the variable impedance element corresponding to the calculated load impedance is obtained by querying.

9. The impedance matching method according to any one of claims 1 to 6, characterized in that: After the step of adjusting the value of the variable impedance element in steps according to the current value of the variable impedance element and the target value according to a plurality of set steps and a set speed corresponding to each set step, the method further includes: Determine whether the plasma is extinguished; If so, the process returns to the step of using the preset starting algorithm to calculate and obtain the adjustment direction and adjustment amount of the variable impedance element in the matching network.

10. The impedance matching method according to any one of claims 1 to 6, characterized in that: After the step of adjusting the value of the variable impedance element in steps according to the current value of the variable impedance element and the target value according to a plurality of set steps and a set speed corresponding to each set step, the method further includes: Determine whether impedance matching is achieved; If not, the current input impedance is calculated based on the detected voltage signal, current signal and angle difference signal at the input end of the impedance matching network, and the adjustment direction and adjustment amount of the variable impedance element are calculated based on the current input impedance and the standard characteristic impedance of the RF power supply. The value of the variable impedance element is adjusted according to the adjustment direction and adjustment amount, and the process returns to the step of determining whether impedance matching is achieved.

11. The impedance matching method according to claim 10, wherein: The determining whether impedance matching is achieved includes: Determine whether the impedance matching parameter is less than a preset threshold; If so, it is determined that impedance matching is achieved; If not, it is determined that impedance matching is not achieved.

12. The impedance matching method according to any one of claims 1 to 6, characterized in that: The determining whether the plasma ignition is successful includes: According to the detected ignition parameter value, calculating whether the difference between the ignition parameter value detected at the next moment and the ignition parameter value detected at the previous moment is greater than a preset ignition parameter threshold; If so, it is determined that the plasma ignition is successful; If not, it is determined that the plasma ignition was unsuccessful.

13. A matching device, characterized in that: It includes an output end signal acquisition unit, a control unit and an impedance matching network composed of a variable impedance element, wherein the output end signal acquisition unit is used to detect the voltage signal, current signal and angle difference signal of the output end of the impedance matching network; The control unit is used to determine whether the plasma ignition is successful; if not, the control unit calculates the adjustment direction and adjustment amount of the variable impedance element using a preset ignition algorithm, adjusts the value of the variable impedance element according to the adjustment direction and the adjustment amount, and then returns to the step of determining whether the plasma ignition is successful; if so, the control unit calculates the load impedance based on the voltage signal, current signal, and angle difference signal at the output end of the impedance matching network detected by the output end signal acquisition unit, and obtains the target value of the variable impedance element based on the load impedance; then, based on the current value of the variable impedance element and the target value, the control unit adjusts the value of the variable impedance element step by step according to multiple set step sizes and a set speed corresponding to each set step size, so as to simultaneously adjust the load impedance from the current real part value and imaginary part value to the real part value and imaginary part value corresponding to the matching point.

14. The matching device according to claim 13, characterized in that The impedance matching network is an L-shaped impedance matching network, wherein the variable impedance element includes a first variable capacitor and a second variable capacitor; the target value of the variable impedance element includes a first target capacitance value of the first variable capacitor and a second target capacitance value of the second variable capacitor; The control unit is further configured to: adjusting the capacitance of the first variable capacitor in steps according to the current capacitance of the first variable capacitor and the first target capacitance, at a first set step length and a first set speed corresponding to each first set step length; and adjusting the capacitance of the second variable capacitor in steps according to the current capacitance of the second variable capacitor and the second target capacitance, at a second set step length and a second set speed corresponding to each second set step length; Wherein, each time period of the first setting step length and each time period of the second setting step length are performed alternately or synchronously.

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