Tuning method for radio frequency matcher

Abstract

The invention discloses a tuning method for a radio frequency matcher, and relates to the technical field of radio frequency matchers. The method comprises the steps that an a coefficient value is written into a matcher program, and a matcher runs; the method comprises the following steps: reading a # imgabs0 # value, a # imgabs1 # value and a Y0 value in a linear network through a sensor; # imgabs2 #, # imgabs3 # and Y0 are substituted into a substitution formula to obtain an estimated value X0 of the current load impedance, and target capacitance # imgabs4 # tar and target capacitance # imgabs5 # tar are calculated according to the estimated value X0 in order to enable the impedance of the power supply end to reach a set value Ytar; the matcher controls a motor of the executing mechanism to enable the capacitors # imgabs6 # and # imgabs7 # to move to the calculated target positions # imgabs8 # tar and # imgabs9 # tar, the executing mechanism works according to a calibration curve between a pre-stored capacitor impedance value and a mechanical position, and the method can be suitable for any linear matching network such as an L shape, a T shape, a Pi shape and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of radio frequency matching devices, and in particular relates to a tuning method for a radio frequency matching device. Background Art

[0002] In the field of semiconductor etching, an RF power supply is usually used to provide power, inject it into the chamber, ionize the process gas, form a plasma, and then accelerate the plasma in the sheath to etch the wafer. In the RF system, impedance mismatch can lead to signal reflection, power loss, device damage and process failure. In order to effectively feed the RF power into the chamber and reduce power reflection, an RF matcher is required for impedance tuning. The tuning is generally performed by adjusting the impedance value of the impedance element through the built-in algorithm of the matcher to automatically achieve tuning. The existing proposal application number is 2024101200973, in which the impedance matching network uses an L-shaped network. The impedance matching method is as follows: Calculate the reflection coefficient modulus between the RF power supply and the matching network ;right Make judgments, such as Less than the threshold , judged as impedance matching, return to S1, continue to monitor the vector voltage of the load feedback, if Greater than , it is judged as impedance mismatch; match iteratively in sequence and adjust the capacitance , adjusting capacitor , calculate N , find out The minimum value in ; If k=1, the value is equal to middle The corresponding capacitor group is determined to be the global optimal capacitor group Pbest of the initial iteration, otherwise, the comparison and , the smaller capacitor group among the two is determined as the individual optimal capacitor group Gbest, if Less than , to meet the impedance matching requirements, the above matching method may fall into a local optimal solution. The matching algorithm contains random factors, and the matching path and matching time of each operation cannot be repeated. Using pure mathematical modeling, the matching speed is obviously slower than considering the physical characteristics of the circuit.

[0003] In order to achieve faster, more stable and more comprehensive RF power input, it is necessary to explore a more intelligent matching method. Summary of the Invention

[0004] The object of the present invention is to provide a tuning method for a radio frequency matching device.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions: The present invention is a tuning method for a radio frequency matching device, comprising writing a coefficient value into a matching device program, and running the matching device; reading a capacitor and a capacitor in a linear network through a sensor; 、Capacitor 2 , the power supply end impedance Y0 value; 、 Substitute Y0 into formula (1) to obtain the estimated value X0 of the current load impedance. According to the estimated value X0, the impedance of the power supply end reaches the set value Ytar, and the target capacitance is calculated. tar, target capacitance tar; the matching device controls the motor of the actuator so that the capacitor and Move to the calculated target position tar and tar, in which the actuator operates based on a pre-stored calibration curve between capacitance impedance and mechanical position;

[0006] in, For capacitor 1, For capacitor 2, Impedance of the power supply, is the load impedance, is the coefficient of the matcher in this machine at a specific operating frequency.

[0007] Preferably, if the re-measured impedance Ynew of the power supply end is the set value Ytar, the matching is successful.

[0008] Preferably, if the impedance Ynew of the power supply end is not the set value Ytar, the linear network is re-measured. new、 new, according to the new measured power supply impedance Ynew, the linear network new、 new iterates again according to the above method.

[0009] Preferably, the relationship between the re-measured impedance Ynew at the power supply end and the set value Ytar complies with formula (2): ,in, is the minimum reflection threshold, the match is successful.

[0010] Preferably, it also includes obtaining the a coefficient value, including: building a variable load matcher test platform; constructing a , According to the table, manually tune the matching device to the table point position, the sensor reads the load end and power supply end impedance data, and records it; 、 , and the power supply impedance corresponding to one of them , rear-end load impedance Substituting the value into formula (1), we get a linear equation system with the number of equations being 、 The number of elements in the matrix; use the least squares method to solve the system of equations and obtain the coefficient value of a.

[0011] The present invention has the following beneficial effects: The present invention is applicable to linear networks: Fast speed: It avoids the blind, random, and iterative search process of traditional algorithms in the capacitance space and directly obtains the target position through calculation.

[0012] Determinism: With the same load and starting point, the algorithm always takes the same path, and the matching time is predictable.

[0013] Universality: Applicable to any linear matching network (L, T, Pi, etc.), only the form of formula (1) needs to be changed accordingly (the number of terms will increase with the number of components) and the calibration process.

[0014] Feedforward: The target action is directly determined through model calculation, which provides the characteristics of feedforward control. Iterative feedback improves robustness. These coefficients are used for rapid calculation and decision-making during runtime, achieving efficient and stable impedance matching.

[0015] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a schematic diagram of the radio frequency circuit; Figure 2 This is an L-shaped circuit diagram; Figure 3 To match the flow chart. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] See also Figure 1-3 As shown, the present invention is a tuning method for a radio frequency matcher.

[0020] Including the calibration of the coefficient, that is, obtaining the value of the coefficient a.

[0021] This step is completed in a laboratory environment or during factory calibration to obtain the coefficients a1-a15 of the specific matching device at a specific operating frequency.

[0022] Specifically including the construction of the platform: Use a mirror matcher (standard test platform) or a variable load matcher test platform. The core is to accurately set and measure the impedance Y at the input end of the matcher, the load impedance X at the output end, and the two capacitors inside the matcher. and value.

[0023] Construct the capacitor matrix: That is, construct a , The matrix form is and Within their adjustable range, they are uniformly assigned values according to a certain step size (e.g. Take 10 points, Take 10 points).

[0024] These points combine to form a take A matrix table containing N points (for example, 10x10=100 points).

[0025] Data collection: Each point in the matrix table ( i, j), manually tune the matching capacitor to this point ( i, j) Use the platform's sensors to accurately measure the load impedance Xij connected to the output end of the matcher and the impedance Yij presented at the input end.

[0026] Record this set of values: i, ,Xij, Yij).

[0027] The matrix table 、 , and the power supply impedance corresponding to one of them , rear-end load impedance Substituting the value into formula (1), we get a linear equation system with the number of equations being 、 The number of elements in the matrix.

[0028] Use the least squares method to solve the system of equations and obtain the coefficient value of a.

[0029] The coefficients a1-a15 are written into the control program (firmware) of the matching device and stored. These coefficients represent the characteristics of the matching device.

[0030] Formula (1) is:

[0031] in, For capacitor 1, For capacitor 2, Impedance of the power supply, is the load impedance, is the coefficient of the matching device in this machine at a specific operating frequency. In actual matching operation, the tuning method of the RF matching device is as follows: Figure 3 As shown, in this embodiment, the capacitor A note ,capacitance Record Used to distinguish and represent the symbols and marks in the above explanation of the technical solution.

[0032] This stage is carried out at the actual application site, and the matcher uses the stored coefficients a1-a15 and real-time measurement data to perform fast matching.

[0033] The a coefficient value is written into the matcher program and the matcher is run.

[0034] The sensor reads the 、 , Y0 value, specifically, the sensor at the input end of the matcher measures the current power supply end impedance Y0 and reads the current position values of the two capacitors and , a motor encoder or position sensor can be used.

[0035] Will 、 , Y0 is substituted into formula (1). The only unknown variable in formula (1) is the load impedance X, and the estimated value X0 of the current load impedance is obtained.

[0036] According to the load impedance estimate X0, the impedance of the power supply end reaches the set value Ytar, and the target capacitance is calculated. tar, target capacitance tar.

[0037] The matching device controls the motor of the actuator so that the capacitor and Move to the calculated target position tar and tar, in which the actuator works based on a pre-stored calibration curve between capacitance impedance value and mechanical position.

[0038] The actuator may be a progressive motor.

[0039] Among them, for a general 50 ohm matching power supply, Ytar can be taken as 50.

[0040] If the impedance Ynew at the power supply end is re-measured and is equal to the set value Ytar, the matching is successful.

[0041] In addition, the relationship between the re-measured power supply impedance Ynew and the set value Ytar conforms to formula (2):

[0042] in, The minimum reflectivity modulus value set for the matcher can be set to 0.01, for example, to successfully match, and then monitor or end.

[0043] In actual operation, the load may change slowly, there may be errors in the actuator, etc., and it is necessary to reverse-engineer or iterate the above method to re-match, monitor or terminate.

[0044] Preferably, if the impedance Ynew of the power supply end is not the set value Ytar, the linear network is re-measured. new、 new.

[0045] According to the new measured power supply impedance Ynew, the linear network new、 new is iterated again according to the above method, where the capacitor in the linear network new、 new and the impedance Ynew at the power supply end are used as the new starting point to re-anchor Xnew, and the above method is installed for fast convergence matching.

[0046] Preferably, if the relationship between the re-measured impedance Ynew at the power supply end and the set value Ytar complies with formula (2), the matching is successful and monitoring is performed or the process ends; otherwise, the iteration continues.

[0047] It is worth noting that in the above system embodiment, the various units included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0048] In addition, a person skilled in the art will understand that all or part of the steps in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a program, and the corresponding program can be stored in a computer-readable storage medium, such as a ROM / RAM, a disk or an optical disk.

[0049] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A tuning method for a radio frequency matching device, characterized in that: The steps include: The a coefficient value is written into the matcher program and the matcher is run; The sensor reads the capacitance of the linear network. 、Capacitor 2 , the power supply end impedance Y0 value; Will 、 Substitute Y0 into formula (1) to obtain the estimated value X0 of the current load impedance. According to the estimated value X0, the impedance of the power supply end reaches the set value Ytar, and the target capacitance is calculated. tar, target capacitance tar; the matching device controls the motor of the actuator so that the capacitor and Move to the calculated target position tar and tar, in which the actuator operates based on a pre-stored calibration curve between capacitance impedance and mechanical position; in, For capacitor 1, For capacitor 2, is the impedance of the power supply, is the load impedance, is the coefficient of the matching device in this machine at a specific operating frequency.

2. The tuning method for a radio frequency matching device according to claim 1, wherein: If the impedance Ynew at the power supply end is re-measured and is equal to the set value Ytar, the matching is successful.

3. The tuning method for a radio frequency matching device according to claim 1, wherein: If the impedance Ynew of the power supply terminal is not the set value Ytar, re-measure the impedance of the linear network. new、 new, according to the new measured power supply impedance Ynew, the linear network new、 new, re-iterate according to the tuning method of the RF matching device.

4. The tuning method for a radio frequency matching device according to claim 3, wherein: The relationship between the re-measured power supply impedance Ynew and the set value Ytar conforms to formula (2) in, The match is successful if the minimum reflectivity modulus value set by the matcher is met.

5. A tuning method for a radio frequency matching device according to any one of claims 1 to 4, characterized in that: It also includes the acquisition of the a coefficient value, including; Build a variable load matcher test platform; Construct a , Matrix table of; According to the table, manually tune the matching device to the table point position, and the sensor reads the impedance data of the load end and the power supply end and records it; The matrix table 、 , and the power supply impedance corresponding to one of them , rear-end load impedance Substituting the value into formula (1), we get a linear equation system with the number of equations being 、 The number of elements in the matrix; use the least squares method to solve the system of equations and obtain the coefficient value of a.

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