JP2017135117A - Impedance adjustment method for high frequency matching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that impedance matching using a characteristic parameter indicating a transmission characteristic of an overall impedance adjustment device cannot be performed if a variable frequency type high frequency power supply 1v is used.SOLUTION: An impedance adjustment device 3A is applied to a high frequency power supply system using a variable frequency type high frequency power supply 1v. A characteristic parameter covering all the combination information of position information C about a variable capacitor 21 and output frequency information F about the high frequency power supply 1v is stored in a memory 70. A T parameter acquisition section 130 acquires the characteristic parameter corresponding to at the present moment (Cnow, Fnow). An output reflection coefficient computation section 140 computes a reflection coefficient Γoutnow of an output end. An virtual output reflection coefficient computation section 160 computes a reflection coefficient Γoutnow' (C, F) at a virtual output end. An approximate reflection coefficient search section 180 provides impedance matching on the basis of a reflection coefficient Γoutnow" (C, F) closest to the reflection coefficient Γoutnow.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an impedance adjustment method for a high-frequency matching system including high-frequency power supply means for supplying high-frequency power to a load and impedance adjustment means for adjusting impedance viewed from the high-frequency power supply means.

  FIG. 8 is a diagram illustrating a configuration example of a high-frequency power supply system. This high-frequency power supply system is a system for performing processing such as plasma etching and plasma CVD on a workpiece such as a semiconductor wafer or a liquid crystal substrate. A load matching unit 4 and a load 5 (plasma processing apparatus 5). The high frequency power source 1 supplies high frequency power to the load 5 through the transmission line 2, the impedance adjusting device 3, and the load connection unit 4. In the load 5 (plasma processing apparatus 5), a plasma discharge gas is introduced into a chamber (not shown) in which a workpiece is placed, and high-frequency power is supplied from a high-frequency power source 1 to an electrode (not shown) in the chamber. The plasma discharge gas is discharged to change from the non-plasma state to the plasma state. And the workpiece is processed using the gas in the plasma state.

  In a load 5 such as a plasma processing apparatus used for applications such as plasma etching and plasma CVD, the plasma state changes from moment to moment as the manufacturing process proceeds. As a result, the impedance (load impedance) of the load 5 changes from moment to moment. In order to efficiently supply power from the high-frequency power source 1 to such a load 5, an impedance ZL viewed from the output end of the high-frequency power source 1 as viewed from the output end of the high-frequency power source 1 (hereinafter referred to as load-side impedance ZL). Need to be adjusted. Therefore, in the high frequency power supply system, the impedance adjusting device 3 is interposed between the high frequency power source 1 and the load 5 (plasma processing device 5).

  The impedance adjusting device 3 is provided between the high frequency power source 1 for supplying high frequency power to the load 5 and the load 5, and has electrical characteristics (capacitance and inductance) of a variable electrical characteristic element (variable capacitor and variable inductor) provided therein. ) Is adjusted to adjust the impedance of the high frequency power supply 1 as viewed from the load 5 side. In this impedance adjusting device 3, the reflected wave power directed from the load 5 to the high-frequency power source 1 is made by matching the impedance of the high-frequency power source 1 and the impedance of the load 5 by setting the electrical characteristics of the variable electrical characteristic element to an appropriate value. Can be minimized to maximize the power supplied to the load.

FIG. 9 is a block diagram showing a configuration example of a high-frequency power supply system including a conventional impedance adjusting device 3P.
The high-frequency power source 1 is a high-frequency power source 1p having a certain frequency with an output frequency (a fundamental frequency (frequency of a fundamental wave) included in the high-frequency power output from the high-frequency power source 1).
As shown in FIG. 9, the impedance adjustment device 3P is provided with an adjustment circuit 20p including a first variable capacitor 21, a second variable capacitor 24, and an inductor 23. The first variable capacitor 21 and the second variable capacitor 24 are a kind of variable electrical characteristic element. In addition, the directional coupler 10 is provided between the input terminal 301 and the adjustment circuit 20p. The output terminal 302 (the output terminal of the adjustment circuit 20p is substantially the same) is connected to the load 5.

  Thereby, the high frequency power output from the high frequency power source 1 is supplied to the load 5 via the directional coupler 10 and the adjustment circuit 20p. The high frequency power output from the high frequency power source 1 and directed to the load 5 is referred to as traveling wave power PF, and the high frequency power reflected by the load 5 and returned to the high frequency power source 1 is referred to as reflected wave power PR.

  As shown in FIG. 9, since the adjustment circuit 20p includes the first variable capacitor 21 and the second variable capacitor 24, the capacitances of the first variable capacitor 21 and the second variable capacitor 24 are adjusted ( The load side impedance ZL can be adjusted (changed). Therefore, the impedance of the high frequency power supply and the impedance of the load 5 can be matched by setting the capacitances of the first variable capacitor 21 and the second variable capacitor 24 to appropriate values. The configuration of the adjustment circuit 20p differs depending on the output frequency of the high-frequency power source 1, the conditions of the load 5, and the like. A variable inductor or the like may be used as the variable electrical characteristic element.

  Since the variable capacitor and the variable inductor can adjust the electric characteristics, in this specification, the variable capacitor and the variable inductor are collectively referred to as a variable electric characteristic element. Also, information such as capacitance and inductance is electrical characteristic information.

  Variable capacitors such as the first variable capacitor 21 and the second variable capacitor 24 are capacitors (sometimes referred to as capacitors) whose capacitance can be changed. These variable capacitors (variable capacitors) have a movable part (not shown) for adjusting the capacitance, and the capacitance can be adjusted by displacing the position of the movable part by a motor or the like. Yes.

  Specifically, at least one of the pair of electrodes of the variable capacitor is a movable electrode. That is, in the case of a variable capacitor, the movable electrode becomes the movable part. And the relative position with the other electrode changes by displacing the position of the movable electrode which is a movable part. That is, the capacitance can be adjusted (changed) by displacing the position of the movable electrode that is the movable portion. The capacitance of such a variable capacitor can be adjusted in a plurality of stages.

  Further, the capacitance with respect to the position of the movable part is known by the specification or experiment of the variable capacitor. Therefore, if the position of the movable part is known, the capacitance can be understood. Therefore, the position information of the movable part can be handled as information representing the capacitance (capacitance information). In a broad concept, the position information of the movable part can be handled as information representing the electric characteristics (electric characteristic information).

  In addition, it is difficult to directly detect the position of the movable part because of its structure. For example, the position of the movable part is detected by detecting the rotational position (rotation amount) of the motor that displaces the position of the movable part. Yes. In this case, the rotational position of the motor may be detected by a pulse signal, or may be detected by a voltage or the like. Thus, the position information of the movable part of the variable capacitor only needs to be specified directly or indirectly.

  In the case of FIG. 9, the adjustment unit 30 can adjust the capacitance of the first variable capacitor 21, and the position detection unit 40 can detect (acquire) the capacitance information of the first variable capacitor 21. Further, the adjustment unit 50 can adjust the capacitance of the second variable capacitor 24, and the position detection unit 60 can detect (acquire) the capacitance information of the second variable capacitor 24.

  The adjustment unit 30 includes a stepping motor, a motor drive circuit, and the like (none of which are not shown) as drive means for the movable part of the first variable capacitor 21. Then, the control unit 100p gives a command signal to the adjustment unit 30, controls the rotation amount of the stepping motor included in the adjustment unit 30, and displaces the position of the movable unit of the first variable capacitor 21 to thereby change the first. The capacitance of the variable capacitor 21 is adjusted. Similarly, the adjustment unit 50 is configured by a stepping motor, a motor drive circuit, or the like (all not shown) as drive means for the movable part of the second variable capacitor 24. Then, the control unit 100p gives a command signal to the adjustment unit 50, controls the amount of rotation of the stepping motor included in the adjustment unit 50, and displaces the position of the movable unit of the second variable capacitor 24 to thereby change the second. The capacitance of the variable capacitor 24 is adjusted.

  The position detection unit 40 detects the stepping motor rotation position (rotation amount) included in the adjustment unit 30. Similarly, the position detection unit 60 detects the stepping motor rotation position (rotation amount) included in the adjustment unit 50.

  In the case of a variable inductor, the structure is different, but like a variable capacitor, it has a movable part, and its inductance can be adjusted (changed) by displacing the position of the movable part by a motor or the like. Yes. Others are the same as those of the variable capacitor, and thus the description thereof is omitted. In the case of a variable inductor, the inductance can be understood if the position of the movable part is known. Therefore, the position information of the movable part can be handled as information representing the inductance (inductance information). In a broad concept, the position information of the movable part can be handled as information representing the electric characteristics (electric characteristic information).

  Moreover, since the variable electrical characteristic elements such as the variable capacitor and the variable inductor are configured as described above, for example, the impedance adjusting device 3P includes the first variable capacitor 21 and the second variable capacitor 24. When the positions of the movable parts of the first variable capacitor 21 and the second variable capacitor 24 can be displaced in 101 steps, the capacitance is 101 × 101 = 10,201 combinations (about 10,000 combinations). It can be changed. That is, the impedance of the impedance adjusting device 3P can be changed to about 10,000 combinations.

  In addition, since the position of the movable part of the variable electrical characteristic element can be displaced in a plurality of stages as described above, by assigning a number to each position that the movable part of the variable electrical characteristic element can take, A combination of positions that the movable part can take can be represented as position information. For example, if the position where the capacitance is minimum is “0” and the position where the capacitance is maximum is “100” in the adjustment range of the movable portion of the variable capacitor, the position of the movable portion of each variable capacitor is “ It can be expressed in 101 levels from “0” to “100”. Therefore, the positions of the movable parts of the first variable capacitor 21 and the second variable capacitor 24 are expressed as position information as (0, 0), (0, 1)... (100, 100). be able to. In Table 1 to be described later, the position information of the movable part of the first variable capacitor 21 is represented by a variable VC1, and the position information of the movable part of the second variable capacitor 24 is represented by a variable VC2. In the above example, “VC1” changes in the range of 0 to 100 (101 steps), and “VC2” also changes in the range of 0 to 100 (101 steps).

  As an impedance adjustment device 3P that performs impedance matching by controlling such a variable electrical characteristic element, for example, a device described in Patent Document 1 (Japanese Patent Laid-Open No. 2006-166612) has been proposed.

  In the impedance adjusting device 3P disclosed in Patent Document 1, first, the characteristic parameters (S parameter or T parameter described later) of the impedance adjusting device with respect to the positions that can be taken by the movable parts of the plurality of variable electrical characteristic elements are measured in advance. Then, it is stored in the memory 70p in correspondence with the position information of the movable part of the variable electrical characteristic element. Then, the control unit 100p detects the traveling wave voltage detection signal and the reflected wave voltage detection signal output from the directional coupler 10, the position information of each movable unit detected by the position detection unit 40 and the position detection unit 60, Impedance matching is performed based on the characteristic parameter information stored in the memory 70p.

  Here, the above-described characteristic parameter treats the entire impedance adjustment device 3 as a transmission device, and the two variable capacitors (the first variable capacitor 21 and the second variable capacitor 24) provided in the impedance adjustment device 3 can be adjusted. In this range, transmission characteristics as a transmission device are measured as S parameter (or T parameter) information.

  Such characteristic parameters indicate transmission characteristics including stray capacitance, inductance components, and the like inside the impedance adjustment device. Therefore, impedance matching is performed accurately by performing impedance matching using the measured characteristic parameters. It is supposed to be possible.

  Table 1 shows an example of the characteristic parameter stored in the memory 70p. Here, an example in which the characteristic parameter stored in the memory 70p is a T parameter is shown. In Table 1, T (0, 0) is obtained when the position of the movable part of the first variable capacitor 21 is “0” and the position of the movable part of the second variable capacitor 24 is “0”. The measured T parameter is shown. Similarly, T (100, 0) was measured when the position of the movable part of the first variable capacitor 21 was “100” and the position of the movable part of the second variable capacitor 24 was “0”. T parameter is shown. The other T parameters are also labeled with the same concept. In Table 1, in order to simplify the description, a part is omitted and described as “...”, But actually, the T parameter is stored.

In addition, as is well known, the S parameter (Scattering Parameter) is a high frequency in which a line having a characteristic impedance (for example, 50Ω) is connected to an input terminal and an output terminal of a predetermined four-terminal network (also referred to as two-terminal-pair network). and shows the transmission characteristics in the four-terminal network when the input signals, as shown in the "number 1", the voltage reflection coefficient of the input side (S11), transmission coefficient of the forward voltage (S _21), It is represented by a matrix composed of elements of a reverse voltage transmission coefficient (S ₁₂ ) and an output-side voltage reflection coefficient (S ₂₂ ). Here, the impedance adjustment device 3 is handled as a four-terminal network, and the S parameter in the impedance adjustment device 3 is calculated.

  The T parameter (Transmission Parameter) is a parameter that can be converted from the S parameter, as shown in “Equation 2”. In general, in a four-terminal network, it is convenient to use the S parameter when measuring the transmission characteristics, and it is convenient to use the T parameter when performing the calculation.

  Further, the S parameter in the four-terminal network as shown in FIG. 10 is defined as “Equation 3”, and the T parameter is defined as “Equation 4”.

  When port 1 is the input side and port 2 is the load side, the relationship between the input reflection coefficient Γin (reflection coefficient at the input end) and the output reflection coefficient Γout (reflection coefficient at the output end) is an S parameter (see “Equation 5”). ) Or T parameter (see “Equation 6”).

JP 2006-166212 A JP 2006-310245 A JP2008-181846

  As described above, in the high frequency power supply system shown in FIG. 9, the output frequency of the high frequency power source 1p is assumed to be a certain frequency. However, for example, as shown in Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-310245), paying attention to the fact that the load side impedance ZL changes when the output frequency of the high frequency power supply 1 is changed, the output frequency of the high frequency power supply 1 is adjusted. A technique for impedance matching has been proposed. That is, the load-side impedance ZL viewed from the output end of the high-frequency power source 1 includes the capacitance component, the inductance component, and the resistance component. Since the capacitance component and the inductance component have different impedances depending on the frequency, the load-side impedance ZL changes when the output frequency of the high-frequency power source 1 is changed. Patent Document 2 is a technology that utilizes such a phenomenon. In the present specification, such a high frequency power source 1 capable of adjusting (changing) the output frequency is referred to as a variable frequency type high frequency power source 1v.

  Further, as described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2008-181846), the impedance adjustment device 3 may be used even when the variable frequency high frequency power supply 1v is used. However, only one variable capacitor of the adjustment circuit 20 provided in the impedance adjustment device 3 is required as shown in FIG. That is, the adjustment circuit 20 can be configured by a variable capacitor 21, a fixed capacitor 22 having a constant capacitance, and an inductor 23. The impedance matching can be performed by adjusting the position of the movable portion of the first variable capacitor 21 and adjusting the output frequency of the high-frequency power source 1v. Since the fixed capacitor 22 of the adjustment circuit 20 has a constant capacitance, an adjustment unit for adjusting the capacitance and a position detection unit for detecting position information of the movable unit are not required.

  However, as in Patent Document 1, the characteristic parameter when impedance matching is performed using the characteristic parameter measured in advance is measured in the case of a certain output frequency. Such a high frequency power supply system using the variable frequency type high frequency power supply 1v is not applicable.

  The present invention has been conceived under the above circumstances, and even when the output frequency is adjusted (changed) using the variable frequency type high frequency power supply 1v, impedance matching using characteristic parameters is performed. It is an object of the present invention to provide a method for adjusting the impedance of a high-frequency matching system.

The impedance adjustment method of the high-frequency matching system provided by the first invention is as follows.
An impedance adjustment method for a high-frequency matching system including high-frequency power supply means for supplying high-frequency power to a load and impedance adjustment means for adjusting impedance viewed from the high-frequency power supply means to the load side,
Information combining the electrical characteristic information of the variable electrical characteristic element provided in the impedance adjusting means and the output frequency information of the high-frequency power supply means can be used as combination information, and the electrical characteristic information and the output frequency information can be taken. When all combinations are targeted, a characteristic parameter storage step for storing a characteristic parameter indicating transmission characteristics of the entire impedance adjusting unit when realizing the target combination in association with combination information;
When information that can acquire the traveling wave voltage traveling from the high-frequency power supply means to the load side and the reflected wave voltage reflected from the load side is high-frequency information, the output terminal of the high-frequency power supply means or the A high frequency information detecting step for detecting high frequency information at the input end of the impedance adjusting means;
A variable element information detecting step of detecting current electric characteristic information of the variable electric characteristic element;
A characteristic parameter acquisition step for acquiring a characteristic parameter corresponding to the combination of the current electrical characteristic information and the current output frequency information by searching among the characteristic parameters stored in the characteristic parameter storage step;
Current output reflection coefficient calculation step of calculating a reflection coefficient at the current output end of the impedance adjusting means based on the high frequency information detected in the high frequency information detection step and the characteristic parameter acquired in the characteristic parameter acquisition step When,
When it is assumed that the reflection coefficient at the input end of the impedance adjusting means is a preset target input reflection coefficient, the impedance corresponding to all or some of the characteristic parameters stored in the characteristic parameter storage step A virtual coefficient for calculating the reflection coefficient at the virtual output terminal of the adjusting means and outputting the calculated reflection coefficient at the plurality of virtual output terminals of the impedance adjusting means in association with the combination information corresponding to each of the reflection coefficients. An output reflection coefficient calculation step;
A virtual output reflection coefficient storage step for storing the reflection coefficient at a plurality of virtual output ends calculated in the virtual output reflection coefficient calculation step in association with the combination information corresponding to each of the reflection coefficients;
Approximate reflection for searching for a reflection coefficient at the virtual output end that most closely approximates the reflection coefficient at the current output end among the reflection coefficients at the virtual output end stored in the virtual output reflection coefficient storage step A coefficient search step;
Electric characteristic information associated with the reflection coefficient at the virtual output end searched in the approximate reflection coefficient searching step is set as target electric characteristic information, and the electric characteristic of the variable electric characteristic element is the electric characteristic indicated by the target electric characteristic information. A target electric characteristic setting step for outputting a command signal so as to be adjusted to the characteristic;
Output frequency information associated with the reflection coefficient at the virtual output end searched in the approximate reflection coefficient search step is set as target output frequency information, and the output frequency of the high-frequency power supply means is set to the frequency indicated by the target output frequency information. A target output frequency setting step for outputting a command signal to the high-frequency power supply means to be adjusted; and
A variable electrical characteristic element adjusting step for adjusting electrical characteristics of the variable electrical characteristic element based on the command signal output in the target electrical characteristic setting step;
It is characterized by having.

The impedance adjustment method of the high-frequency matching system provided by the second invention relates to the characteristic parameter stored in the characteristic parameter storage step,
The characteristic parameter stored in the characteristic parameter storing step is a characteristic parameter measured for each combination of the target combinations or a characteristic parameter obtained by converting the measured characteristic parameter.

The impedance adjustment method of the high-frequency matching system provided by the third invention relates to the characteristic parameter stored in the characteristic parameter storage step,
The characteristic parameter stored in the characteristic parameter storage step is another parameter estimated by calculation using the characteristic parameter measured for each partial combination of the target combination and the characteristic parameter measured for each partial combination. It is a characteristic parameter that is a combination characteristic parameter or a characteristic parameter obtained by converting those characteristic parameters.

An impedance adjustment method for a high-frequency matching system provided by a fourth invention relates to the characteristic parameter storage step, and the characteristic parameter storage step includes
A first characteristic parameter storage step of storing a characteristic parameter measured for each combination of the target combination or a characteristic parameter obtained by converting the measured characteristic parameter in association with combination information;
A second characteristic parameter storage step of storing the characteristic parameter of the estimated other combination or the characteristic parameter obtained by converting the estimated characteristic parameter of the other combination in association with combination information;
It is characterized by including.

The impedance adjustment method of the high-frequency matching system provided by the fifth invention relates to the current output reflection coefficient calculation step, and the current output reflection coefficient calculation step includes:
Based on the high frequency information detected in the high frequency information detection step, the reflection coefficient at the input end is calculated, and based on the calculated reflection coefficient at the input end and the characteristic parameter acquired in the characteristic parameter acquisition step, It is characterized by calculating the reflection coefficient at the current output end.

The impedance adjustment method for the high-frequency matching system provided by the sixth invention is as follows.
Based on the high frequency information detected in the high frequency information detection step, further comprising a frequency detection step of detecting output frequency information of the high frequency power supply means,
The characteristic parameter acquisition step uses the output frequency information detected in the frequency detection step as current output frequency information.

An impedance adjustment method for a high-frequency matching system provided by a seventh invention relates to the characteristic parameter acquisition step, and the characteristic parameter acquisition step includes:
The output frequency recognized by the high-frequency power supply means is used as current output frequency information.

The impedance adjustment method for the high-frequency matching system provided by the eighth invention is as follows.
The measured characteristic parameter is an S parameter, and the converted characteristic parameter is a T parameter that can be converted from the S parameter.

The impedance adjustment method of the high-frequency matching system provided by the ninth invention relates to high-frequency information, and the high-frequency information is
A traveling wave voltage traveling from the high-frequency power source to the load side and a reflected wave voltage reflected from the load side are characterized.

  According to the present invention, there is provided an impedance adjustment method for a high frequency matching system capable of performing impedance matching using characteristic parameters even when the output frequency is adjusted (changed) using a variable frequency high frequency power supply means. be able to.

It is a block diagram which shows the structural example of the high frequency electric power supply system to which the impedance adjustment apparatus 3A is applied. An example of the S parameter or the T parameter stored in the memory 70 is illustrated. It is a figure for demonstrating the method of calculating | requiring the S parameter which is not measured by bilinear interpolation. It is a figure which shows the structure of the measurement circuit for measuring S parameter of 3 A of impedance adjustment apparatuses. 2 is a functional block diagram of a control unit 100. FIG. It is a functional block diagram of the control part 100a in 2nd Embodiment. An example of the T parameter targeted by the virtual output reflection coefficient calculation unit 160a is shown. It is a figure which shows the structural example of a high frequency electric power supply system. It is a block diagram which shows the structural example of the high frequency electric power supply system containing the conventional impedance adjusting device 3P. It is a figure which shows the concept of 4 terminal circuitry. 2 is a diagram illustrating an example of an adjustment circuit 20. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure as the past.

[First Embodiment]
FIG. 1 is a block diagram illustrating a configuration example of a high-frequency power supply system to which the impedance adjustment device 3A is applied.

  This system supplies a high-frequency power to a workpiece such as a semiconductor wafer or a liquid crystal substrate, and performs a processing process such as plasma etching. This system includes a variable frequency high frequency power supply 1v, a transmission line 2, an impedance adjustment device 3A, a load connection unit 4, and a load 5 including a plasma processing device. In the present specification, a system in which the high frequency power supply 1v and the impedance adjustment device 3A are combined is referred to as a high frequency matching system.

  An impedance adjusting device 3A is connected to the high frequency power source 1v via a transmission line 2 made of, for example, a coaxial cable. The impedance adjusting device 3A is connected to a load connecting portion 4 made of a copper plate that is shielded to suppress leakage of electromagnetic waves, for example. A load 5 is connected to the load connection unit 4.

  The high frequency power supply 1v has a frequency in a radio frequency band (generally, a frequency of about several hundred KHz to several tens of MHz, for example, a frequency of 400 kHz, 2 MHz, 13.56 MHz, 50 MHz, etc.) with respect to the load 5. An apparatus for supplying high-frequency power. In addition, let the fundamental frequency of the high frequency electric power output from the high frequency power supply 1v be output frequency.

The high frequency power supply 1v can change the output frequency within a predetermined range, and changes the output frequency by a command signal. The variable frequency range is appropriately set in consideration of the performance of an oscillator (not shown) provided in the high frequency power supply 1v. For example, when the center frequency is 2 MHz, the output frequency can be changed within a range of about 2 MHz ± 10% (1.8 to 2.2 MHz).
At this time, for example, the lower limit frequency of the variable range of the output frequency is set to “0”, the upper limit frequency of the variable range of the output frequency is set to “100”, and the output frequency can be changed in 101 steps from “0” to “100”. Designed to. That is, when the variable range of the output frequency is 2 MHz ± 10% (1.8 to 2.2 MHz), “0” is 1.8 MHz and “100” is 2.2 MHz. The output frequency is changed (every 4 kHz).

  Of course, the output frequency and the variable range of the output frequency are not limited to the above. For example, it may be set to a high output frequency of about several hundred MHz. In some cases, the output frequency may be changed within a range of about 2 MHz ± 5% (1.9 to 2.1).

  The high frequency power source 1v outputs the output frequency recognized by the high frequency power source 1v as the power source recognition output frequency Fge. The power supply recognition output frequency Fge output from the high frequency power supply 1v is input to the control unit 100 of the impedance adjusting device 3A described later. Further, as will be described later, target output frequency information Fmat for impedance matching is output from the control unit 100 of the impedance adjusting device 3A, and the target output frequency information Fmat is input to the high frequency power source 1v. The high frequency power supply 1v changes the output frequency based on the target output frequency information Fmat.

  The load 5 is a plasma processing apparatus for processing a workpiece such as a semiconductor wafer or a liquid crystal substrate using a method such as etching or CVD. In the plasma processing apparatus, various processing processes are executed according to the processing purpose of the workpiece. For example, when etching a workpiece, a processing process in which the gas type, gas pressure, high-frequency power supply power value, high-frequency power supply time, and the like according to the etching are appropriately set is performed. Is called. In the plasma processing apparatus, a plasma discharge gas is introduced into a chamber (not shown) in which a workpiece is placed. In addition, a high frequency power is applied from a high frequency power source 1v to an electrode (not shown) in the chamber to discharge a plasma discharge gas to change from a non-plasma state to a plasma state. And the workpiece is processed using the gas in the plasma state.

  The impedance adjustment device 3 </ b> A is for matching the impedances of the high-frequency power source 1 v connected to the input end 301 and the load 5 connected to the output end 302. More specifically, for example, the impedance (output impedance) when the high frequency power supply 1v side is viewed from the input end 301 is designed to be 50Ω, and the high frequency power supply 1v is connected to the input end 301 of the impedance adjusting device 3A by the transmission line 2 having a characteristic impedance of 50Ω. Assuming that the impedance adjustment device 3A is connected, the impedance adjustment device 3A has a function of bringing the impedance viewed from the input end 301 of the impedance adjustment device 3A toward the load 5 closer to 50Ω. As a result, the load side impedance ZL when the load 5 side is seen from the output end of the high frequency power supply 1v is brought close to 50Ω.

  In this embodiment, the characteristic impedance is 50Ω, but the characteristic impedance is not limited to 50Ω. In addition, it is desirable to make the load side impedance ZL coincide with the characteristic impedance so that the input reflection coefficient Γin at the input terminal 301 of the impedance adjusting device 3 is 0. Usually, the input reflection coefficient Γin is equal to or less than a predetermined allowable value. If this is the case, it is considered that the impedance is matched.

In such an impedance adjustment device 3A, a directional coupler 10, a control unit 100, an adjustment circuit 20, an adjustment unit 30, a position detection unit 40, and a memory 70 are provided. The adjustment circuit 20 includes a variable capacitor 21 (which is substantially the same as the first variable capacitor 21 in FIG. 9 and has the same sign) as a variable electrical characteristic element, a capacitor 22 having a fixed impedance, and an inductor 23. ing. And while adjusting the position of the movable part of the variable capacitor 21 provided in the adjustment circuit 20 and adjusting the output frequency of the high-frequency power source 1v, impedance matching is performed, which will be described in detail later.
As described above, the position information of the movable part of the variable capacitor 21 can be handled as information representing the capacitance (capacitance information). In a broad concept, the position information of the movable part can be handled as information representing the electric characteristics (electric characteristic information).

  The configuration of the adjustment circuit 20 is not limited to that shown in FIG. For example, the adjustment circuit 20 shown in FIG. 1 is generally called an inverted L type, but a known adjustment circuit such as a π type can also be used. What type of adjustment circuit is used depends on the output frequency of the high-frequency power source 1v, the condition of the load 5, and the like.

The directional coupler 10 detects a high frequency (hereinafter referred to as traveling wave) traveling from the high frequency power source 1v toward the load 5 and a high frequency reflected from the load 5 (hereinafter referred to as reflected wave) separately. To do. The detection signal on the traveling wave side is output as the traveling wave voltage, and the detection signal on the reflected wave side is output as the reflected wave voltage. The directional coupler 10 has, for example, one input port 11 and three output ports 12, 13, and 14. The input port 11 is connected to a high frequency power supply 1v, and the first output port 12 is connected to an adjustment circuit. 20 is connected. The second output port 13 and the third output port 14 are connected to the control unit 100.
The directional coupler 10 functions as a part of the high frequency information detecting means of the present invention. A combination of the directional coupler 10 and a vectorization unit 110 described later is an example of the high-frequency information detection means of the present invention.

  A traveling wave input from the input port 11 is output from the first output port 12, and a reflected wave input from the first output port 12 is output from the input port 11. The traveling wave is attenuated to an appropriate level and detected, and is output from the second output port 13 as a traveling wave voltage detection signal. The reflected wave is detected after being attenuated to an appropriate level, and is output from the third output port 14 as a detection signal of the reflected wave voltage.

  Instead of the directional coupler 10, an input side detector may be used. The input-side detector detects, for example, a high-frequency voltage, a high-frequency current, and a phase difference (phase difference between the high-frequency voltage and the high-frequency current) that are input from the high-frequency power source 1v to the input terminal 301. The high frequency voltage, high frequency current and phase difference detected by the input side detector are input to the control unit 100.

  The control unit 100 serves as a control center of the impedance adjusting device 3A, and includes a CPU, a memory, a ROM, and the like (not shown). Further, for example, a configuration using a gate array such as an FPGA (Field Programmable Gate Array) capable of appropriately defining and changing an internal logic circuit can be used. The control unit 100 adjusts the impedance of the adjustment circuit 20 of the impedance adjustment device 3A by changing the capacitance of the variable capacitor 21 and the output frequency of the high-frequency power source 1v based on the output of the directional coupler 10 and the like. is there.

  The variable capacitor 21 is connected to an adjustment unit 30 for displacing the position of the movable unit. The adjustment unit 30 is configured by a stepping motor, a motor drive circuit, or the like (all not shown) as drive means for the movable unit. Then, the control unit 100 gives a command signal to the adjustment unit 30, controls the rotation amount of the stepping motor included in the adjustment unit 30, and displaces the position of the movable unit of the variable capacitor 21 to thereby change the capacitance of the variable capacitor 21. Adjust. In the present embodiment, the capacitance of the variable capacitor 21 can be adjusted, for example, in 101 steps. The adjustment unit 30 is an example of a variable electrical characteristic element adjustment unit of the present invention.

  The variable capacitor 21 is provided with a position detection unit 40 for detecting the position of the movable unit adjusted by the adjustment unit 30. The position information of the movable part of the variable capacitor 21 detected by the position detection unit 40 is sent to the control unit 100 and recognized by the control unit 100. The position detection unit 40 is an example of variable element information detection means of the present invention.

  In addition, a memory 70 is connected to the control unit 100, and the memory 70 stores S parameters as shown in Table 2 or T parameters obtained by converting S parameters as shown in Table 3. Yes. The function of the control unit 100 will be described later. The memory 70 is an example of the characteristic parameter storage means (first characteristic parameter storage means, second characteristic parameter storage means) of the present invention.

  In this embodiment, the position information of the movable part of the variable capacitor 21 is represented by a variable C, the output frequency information of the high frequency power supply 1v is represented by a variable F, and the position of the movable part of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. Is expressed in a coordinate format such as (C, F). In the above example, “C” changes in the range of 0 to 100 (101 steps), and “F” also changes in the range of 0 to 100 (101 steps). Of course, you may make it change in another range. Note that the axis of the variable C when expressed in the coordinate format as described above corresponds to the first axis of the present invention, and the axis of the variable F corresponds to the second axis of the present invention.

  The S parameter shown in Table 2 is measured using the position of the movable part of the variable capacitor 21 and the output frequency as variables, and the position of the movable part of the variable capacitor 21 is 101 levels from “0” to “100”. This is an example of the T parameter measured when the output frequency of the high-frequency power source 1v can be changed to 101 levels from “0” to “100”. The T parameter shown in Table 3 is obtained by converting the S parameter shown in Table 2.

  In Table 2, S (0, 0) indicates an S parameter measured when the position of the movable portion of the variable capacitor 21 is “0” and the output frequency is a frequency indicating “0”. Similarly, S (100, 0) indicates an S parameter measured when the position of the movable portion of the variable capacitor 21 is “100” and the output frequency is a frequency indicating “0”. The other S parameters are also given the same concept.

  Further, since the T parameter shown in Table 3 is obtained by converting the S parameter, the reference numeral is assigned in the same way as the S parameter. That is, T (0, 0) indicates a T parameter measured when the position of the movable portion of the variable capacitor 21 is “0” and the output frequency is a frequency indicating “0”. Similarly, T (100, 0) indicates a T parameter measured when the position of the movable portion of the variable capacitor 21 is “100” and the output frequency is a frequency indicating “0”. The other T parameters are also labeled with the same concept.

FIG. 2 illustrates an example of the S parameter or the T parameter stored in the memory 70. That is, an example of the measured S parameter or T parameter is illustrated. In FIG. 2, the horizontal axis is the position information C of the movable part of the variable capacitor 21, and the vertical axis is the output frequency information F of the high-frequency power source 1 v. In addition, black circles indicate the measured S parameter or T parameter.
In FIG. 2, in order to simplify the drawing, a part of the horizontal axis and the vertical axis is omitted, but the S parameter or the T parameter is stored in the memory 70 in increments of one. That is, the S parameter or the T parameter for all combinations of the value that can be taken by the position of the movable portion of the variable capacitor 21 and the value that can be taken by the output frequency of the high frequency power supply 1v is stored in the memory 70.

  By the way, (0, 0) and (100, 0) as described above indicate combination information between the position of the movable portion of the variable capacitor 21 and the output frequency of the high-frequency power supply 1v. For example, the position of the corresponding movable part of the variable capacitor 21 and the output frequency of the high-frequency power source 1v can be known. That is, the capacitance information (electric characteristic information) of the variable capacitor 21 and the output frequency of the high-frequency power source 1v are known. Therefore, the memory 70 does not simply store the S parameter and the T parameter, but stores the S parameter and the T parameter in association with the combination information of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. .

  As described above, it is easy to use the S parameter when measuring the transmission characteristics, and it is convenient to use the T parameter when performing the calculation. Therefore, the T parameter is used when performing impedance matching. For this reason, normally, the measured S parameter converted into the T parameter is stored in the memory 70. When the S parameter is stored in the memory 70, it is converted from the S parameter to the T parameter when necessary. However, if the S parameter is converted to the T parameter during impedance matching, the calculation load increases. Therefore, it is preferable to store the T parameter in the memory 70 in advance. Therefore, in the following description, it is assumed that the T parameter is stored in the memory 70 and impedance matching is performed using the T parameter.

  The S parameter corresponds to the position of the movable part of the variable capacitor 21 and the output frequency of the high-frequency power source 1v. Therefore, from the viewpoint of accuracy, the value of the movable part of the variable capacitor 21 and the high-frequency power source It is preferable to measure the S parameter for all possible combinations of values that the output frequency of 1v can take.

  However, as described above, the position of the movable portion of the variable capacitor 21 and the output frequency of the high-frequency power supply 1v can be displaced (adjustable) in a plurality of stages as described above. If an attempt is made to measure the S parameter, an enormous amount of S parameter is measured, which requires a lot of man-hours. Therefore, S parameters are not measured for all combinations, but S parameters are measured for some combinations, and S parameters are estimated by linear interpolation for unmeasured S parameters. A technique may be used. The same applies to the T parameter obtained by converting the S parameter.

  For example, an interpolation operation by linear approximation may be performed on each of the S parameter elements S11, S12, S21, and S22. Similarly, the T parameter obtained by converting the S parameter may be subjected to interpolation calculation by linear approximation for each of the T parameter elements T11, T12, T21, and T22. As an interpolation calculation method, for example, an interpolation method called bi-linear may be used (hereinafter referred to as bi-linear interpolation).

  In Table 2 above, an example in which the S parameter is measured for all possible combinations of the combination information of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v is shown. As described above, S parameters may be measured for some combinations, and S parameters corresponding to other combinations may be estimated by calculation using S parameters measured for some combinations. The estimation by calculation may be performed by, for example, bilinear interpolation.

  The same applies to the T parameter obtained by converting the S parameter. In Table 3, all combinations that can be taken by the combination information of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power source 1v are targeted. As shown in Table 5, T parameters corresponding to other combinations may be estimated by calculation using T parameters for some combinations. In this case as well, estimation by calculation may be performed by bilinear interpolation, for example.

  FIG. 3 is a diagram for explaining a method for obtaining an unmeasured S parameter by bilinear interpolation. In FIG. 3, when the position of the movable part of the variable capacitor 21 and the output frequency of the high-frequency power source 1v are used as variables, the measurement is performed based on the measured values of S parameters measured for some combinations of both. A method for obtaining a non-S parameter by bilinear interpolation will be described. In FIG. 3, the S parameter element S11 is taken as an example.

  In this specification, the element of the S parameter is represented by “element name of S parameter (S11, etc.)” + “Combination information (C, F)”. For example, the element S11 of S (10,10) is S11 (10,10), the element S11 of S (10,20) is S11 (10,20), and the element S11 of S (20,10) is S11 (20,20). 10), the element S11 of S (20, 20) is represented as S11 (20, 20). Therefore, in FIG. 3, the measured value of S11 (10,10) is 100, the measured value of S11 (10,20) is 170, the measured value of S11 (20,10) is 160, and the measured value is S11 (20,20). The value is 200. Note that each value example of the element S11 shown in FIG. 3 is not an actual measurement value, but a numerical value that facilitates explanation of bilinear interpolation.

In the case of FIG. 3, for example, the estimated value of S11 (18, 16) can be obtained by the following first to third steps.
First step: Using the measured value of S11 (10, 10) and the measured value of S11 (20, 10), an interpolation operation is performed to obtain an estimated value of S11 (18, 10).
Second step: Using the measured value of S11 (10, 20) and the measured value of S11 (20, 20), an interpolation operation is performed to obtain an estimated value of S11 (18, 20).
Third step: To obtain the estimated value of S11 (18, 16) using the estimated value of S11 (18, 10) and the estimated value of S11 (18, 20) obtained in the first step and the second step. Interpolation calculation is performed.

Specifically, it is as follows.
Estimated value of S11 (18, 10): 100 × 0.2 + 160 × 0.8 = 148
Estimated value of S11 (18, 20): 170 × 0.2 + 200 × 0.8 = 194
Estimated value of S11 (18, 16): 148 × 0.4 + 194 × 0.6 = 175.6
Therefore, the estimated value of S11 (18, 16) is 175.6.

  Other elements S12 (18, 16), S21 (18, 16), and S22 (18, 16) can be similarly estimated. Therefore, even if the S parameter is not measured, each element S11, S12, S21, S22 can be obtained.

  If the S parameter for which an estimated value is to be obtained by interpolation is S (18, 20), S11 is based on the measured value of S11 (10, 20) and the measured value of S11 (20, 20). An estimated value of (18, 20) can be obtained. Other elements S12 (18, 20), S21 (18, 20), and S22 (18, 20) can be similarly estimated.

  That is, since the S parameter is usually measured in a grid pattern as shown in Table 4, when the S parameter is obtained by the interpolation calculation, the interpolation calculation is performed based on the four measured S parameters. If there is an S parameter to be obtained between the S parameters, the calculation can be simplified.

  Further, when the S parameter is measured in a grid pattern as shown in Table 4, there is an advantage that the interpolation calculation can be easily performed. Of course, there are cases where the interpolation calculation can be performed even if the S parameter is not measured in a grid pattern.

  In the above, among the measured S parameters, S parameters [S (10, 10)], [S (20, 10)], [S (10 , 20)], [S (20, 20)], the estimated value of the S parameter [S (18, 16)] is calculated. However, the present invention is not limited to this. For example, based on [S (0,0)], [S (30,0)], [S (0,30)], [S (30,30)], the S parameter [S (18,16)] ] May be interpolated. The measured S parameter used for the interpolation calculation may not be adjacent to the S parameter [S (18, 16)] to be estimated. However, it is considered that the accuracy of the estimated value becomes worse as the interval between the S parameter to be estimated and the measured S parameter used for the interpolation calculation increases. Therefore, which S parameter is used for the interpolation calculation depends on the accuracy and convenience. May be appropriately determined in consideration of the above.

  As described above, the S parameter that is not measured can be estimated from the previously measured S parameter by the interpolation calculation. Therefore, the estimated S parameter may be stored in the memory 70 in advance. Further, a T parameter obtained by converting the S parameter may be stored.

When the estimated S parameter or the T parameter obtained by converting the estimated S parameter is stored in the memory 70 as described above, for example, the measured S parameter or the T parameter obtained by converting the measured S parameter is stored in the first memory. The estimated S parameter or the T parameter obtained by converting the estimated S parameter may be stored in the second storage area. In other words, the area for storing the measured S parameter or the T parameter obtained by converting the measured S parameter is the first storage area, and the area for storing the estimated S parameter or the T parameter obtained by converting the estimated S parameter is the first storage area. 2 storage areas.
Of course, the first storage area and the second storage area may be provided in the same hardware or in different hardware. Further, when the first storage area and the second storage area are provided on the same hardware, the first storage area and the second storage area may or may not be divided for each area of a predetermined capacity. May be. It should be noted that it is preferable to distinguish whether the stored parameter is a measured parameter (a parameter obtained by converting the measured parameter) or an estimated parameter (a parameter obtained by converting the estimated parameter).

  Next, a method for measuring S parameter data will be described.

[Measurement circuit for measuring S-parameters]
FIG. 4 is a diagram showing a configuration of a measurement circuit for measuring the S parameter of the impedance adjusting device 3A. The configuration of this measurement circuit is assembled in advance in a factory, for example, before product shipment.

  As shown in FIG. 4, the S parameter of the impedance adjusting device 3A is measured using a network analyzer 80 having an input / output impedance of 50Ω, for example. Therefore, the first input / output terminal 81 of the network analyzer 80 is connected to the input terminal 301 of the impedance adjustment device 3A, and the second input / output terminal 82 of the network analyzer 80 is connected to the output terminal 302 of the impedance adjustment device 3A. . The control terminal 83 of the network analyzer 80 is connected to the control unit 100 of the impedance adjusting device 3A.

  The directional coupler 10 is not used when measuring the characteristic parameter (S parameter in this example), but is actually used when manufacturing a semiconductor, a flat panel display, or the like.

[S-parameter measurement procedure]
In the measurement circuit shown in FIG. 4, the position of the movable portion of the variable capacitor 21 is changed step by step, and the high frequency frequency output from the network analyzer 80 is changed step by step, while the network analyzer 80 changes the impedance adjustment device. The S parameter of 3A is measured. Hereinafter, this procedure will be described.
The S parameter is measured by using the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power source 1v as variables, and the variable capacitor 21 can be displaced in 101 steps from 0 to 100. It is assumed that the output frequency of 1v can be changed to 101 steps from 0 to 100.

  First, the position of the movable portion of the variable capacitor 21 is set to, for example, “0” by the control unit 100, and a frequency corresponding to, for example, “0” (for example, 1.8 MHz) from the first input / output terminal 81 of the network analyzer 80. ) Is input to the input terminal 301 of the impedance adjusting device 3A. This high frequency corresponds to the output frequency of the high frequency power supplied from the high frequency power source 1v to the load 5.

  A part of the high frequency (incident wave) output from the network analyzer 80 is reflected by the input terminal 301 of the impedance adjusting device 3A, and is input to the network analyzer 80 from the first input / output terminal 81, and the rest is in the impedance adjusting device 3A. And is output from the output terminal 302 and input to the network analyzer 80 from the second input / output terminal 82.

  The reflected wave and the transmitted wave are detected inside the network analyzer 80, and the input-side voltage reflection coefficient (S11) and the forward voltage are transmitted among the S parameters using the incident wave, the reflected wave and the transmitted wave. The coefficient (S21) is measured. That is, if the incident wave, the reflected wave, and the transmitted wave are a1, b1, and b2, respectively, the voltage reflection coefficient (S11) and the forward voltage are calculated by performing the calculation process of S11 = b1 / a1 and S21 = b2 / a1. The transmission coefficient (S21) is measured.

  Next, the same high frequency is input from the second input / output terminal 82 of the network analyzer 80 to the output terminal 302 of the impedance adjusting device 3A. A part of the high frequency (incident wave) output from the network analyzer 80 is reflected at the output end 302 of the impedance adjustment device 3A, and is input to the network analyzer 80 from the second input / output terminal 82, and the rest is in the impedance adjustment device 3A. , And is output from the input terminal 301 and input to the network analyzer 80 from the first input / output terminal 81.

  Then, the reflected wave and the transmitted wave are detected inside the network analyzer 80, respectively. Of these S-parameters, the reverse voltage transfer coefficient (S12) and the output voltage reflection coefficient (S22) are measured using these incident, reflected and transmitted waves. That is, if the incident wave, the reflected wave, and the transmitted wave are a2, b2, and b1, respectively, the reverse voltage transmission coefficient (S12) and the output are obtained by performing the processing of S12 = b1 / a2 and S22 = b2 / a2. The voltage reflection coefficient (S22) on the side is measured.

  Thus, in conjunction with the previous step, the S parameter “S (when the position of the movable portion of the variable capacitor 21 is“ 0 ”and the output frequency is“ 0 ”(corresponding to 1.8 MHz in this example). 0,0) ", the forward voltage transmission coefficient (S21), the reverse voltage transmission coefficient (S12), and the output voltage reflection coefficient (S22). Become. That is, the S parameter “S (0, 0)” when the position of the movable portion of the variable capacitor 21 is “0” and the output frequency of the high frequency power supply 1v is “0” is measured. The measured S parameter is sent from the control terminal 83 of the network analyzer 80 to the control unit 100 of the impedance adjusting device 3A.

  The control unit 100 converts the S parameter measured using the above-described “Equation 2” into a T parameter. The converted T parameter has a correspondence relationship between the position of the movable portion of the variable capacitor 21 by the control unit 100 and the high-frequency frequency output from the network analyzer 80 (corresponding to the output frequency of the high-frequency power source 1v). After that, it is sent to the memory 70 and stored in the memory 70.

  Thereafter, the desired S parameter can be similarly obtained by sequentially changing the combination information of the position of the movable portion of the variable capacitor 21 and the high-frequency frequency output from the network analyzer 80. For example, for example, S (0, 0), S (0, 1),... S (0, 99), S (0, 100), S (1, 0), S (1, 1),. .. S parameters may be measured sequentially in the order of S (100, 99) and S (100, 100). Of course, the order of measurement is not limited to this order.

  The measured S parameter is sequentially converted into a T parameter. In the converted T parameter, the position of the movable part of the variable capacitor 21 and the high frequency output from the network analyzer 80 (corresponding to the output frequency of the high frequency power supply 1v) are related by the control unit 100. Is sent to the memory 70 and stored in the memory 70.

  In the above description, each time one S parameter is measured, it is converted into a T parameter. However, the present invention is not limited to this, and each time a plurality of S parameters are measured, the T parameter is converted into a T parameter. Alternatively, the S parameter to be measured may be measured and then converted to the T parameter. For this purpose, both an S parameter memory and a T parameter memory may be provided as necessary.

  The S parameter and T parameter data may be output to a display (not shown) of the network analyzer 80, a display provided outside the impedance adjustment device 3A, a printer (both not shown), or the like. . Of course, it may be output to various external devices (not shown).

  In this way, when the S parameter of the impedance adjustment device 3A is measured, the impedance adjustment device 3A is shipped from a factory, for example, and is interposed between the high-frequency power source 1v and the load 5 as described above. It is used when actually manufacturing semiconductors and flat panel displays in the field.

[Operation of Impedance Adjustment Device 3A]
Next, the operation of the impedance adjusting device 3A actually used as a high frequency power supply system will be described with reference to FIG.

  FIG. 5 is a functional block diagram of the control unit 100. From the viewpoint of function, the control unit 100 includes a vectorization unit 110, a frequency detection unit 120, a T parameter acquisition unit 130, a current output reflection coefficient calculation unit 140, a target input reflection coefficient setting unit 150, as shown in FIG. The virtual output reflection coefficient calculation unit 160, the memory 170, the approximate reflection coefficient search unit 180, the target position setting unit 191 and the target frequency setting unit 192 are included.

  The frequency detection unit 120 is an example of the frequency detection unit of the present invention, the T parameter acquisition unit 130 is an example of the characteristic parameter acquisition unit of the present invention, and the current output reflection coefficient calculation unit 140 is the present invention. The virtual output reflection coefficient calculation unit 160 is an example of a virtual output reflection coefficient calculation unit of the present invention, and the memory 170 is a virtual output reflection coefficient storage unit of the present invention. The approximate reflection coefficient search unit 180 is an example of the approximate reflection coefficient search unit of the present invention, the target position setting unit 191 is an example of the target electrical characteristic setting unit of the present invention, and the target frequency setting unit 192. These are examples of the target output frequency setting means of the present invention.

  When high-frequency power is supplied to the load 5 by the high-frequency power source 1v, the traveling wave and the reflected wave are separated and detected by the directional coupler 10. The detection signal on the traveling wave side is output as the traveling wave voltage, and the detection signal on the reflected wave side is output as the reflected wave voltage. In the vectorization unit 110, the output of the directional coupler 10 is input, the input signal is sampled at a predetermined interval, and the traveling wave voltage Vfinow at the current input terminal 301 and vector information including magnitude and phase information are obtained. The reflected wave voltage Vrinow is output. An A / D converter (not shown) is provided to convert the output of the directional coupler 10 into digital information.

In addition, when an input side detector is used instead of the directional coupler 10 or the like, an A / D converter (not shown) is provided to convert the output of the input side detector into digital information. By this method, the traveling wave voltage Vfinow and the reflected wave voltage Vrinow are obtained based on the information input from the input side detector.
In this case, the one including the input side detector and the part for obtaining the traveling wave voltage Vfinow and the reflected wave voltage Vrinow based on the information inputted from the input side detector is an example of the high frequency information detecting means of the present invention. Become.

  When the traveling wave voltage Vfinow and the reflected wave voltage Vrinow at the current input terminal 301 are output from the vectorization unit 110, they are input to the current output reflection coefficient calculation unit 140.

  As shown in “Expression 7”, by dividing the traveling wave voltage Vfinow from the reflected wave voltage Vrinow, the current reflection coefficient Γinnow at the input terminal 301 (hereinafter, input reflection coefficient Γinnow) can be calculated. The absolute value of the input reflection coefficient Γinnow (input reflection coefficient absolute value) is | Γinnow |.

The frequency detector 120 receives the traveling wave voltage Vfinow, detects the output frequency of the high frequency power supplied from the high frequency power source 1v to the load 5 by a known method, and outputs it as the current output frequency Fnow. The current output frequency Fnow is sent to the T parameter acquisition unit 130 and the target frequency setting unit 192. Known methods include, for example, a frequency detection method using a PLL (Phase-locked loop), a frequency detection method using a zero cross method, and the like. Of course, it is not limited to these methods, and other methods may be used.
In addition, as described above, when an input side detector is used instead of the directional coupler 10, the frequency detection unit 120 inputs, for example, a high frequency voltage detected by the input side detector, and this high frequency Based on the voltage, the output frequency of the high-frequency power supplied from the high-frequency power source 1v to the load 5 may be detected.

  As described above, the S parameter used in the present embodiment is measured assuming that the high frequency output from the network analyzer 80 corresponds to the output frequency of the high frequency power supplied from the high frequency power supply 1v to the load 5. It has been done. Therefore, it is necessary to minimize the deviation between the output frequency detected by the frequency detection unit 120 and the high frequency output from the network analyzer 80 when measuring the S parameter.

  From this point of view, the deviation between the power supply recognition output frequency Fge recognized by the high frequency power supply 1v and the current output frequency Fnow detected by the frequency detection unit 120 needs to be as small as possible. . If the manufacturer of the high frequency power supply 1v and the manufacturer of the impedance adjusting device 3 are the same, the above deviation can be made as small as possible. However, if the manufacturer of the high frequency power supply 1v and the manufacturer of the impedance adjustment device 3 are different, there is a risk of deviation. Then, accurate impedance matching cannot be performed. Therefore, in the present embodiment, the impedance adjusting device 3 (frequency detection unit 120) detects the output frequency of the high frequency power supplied from the high frequency power source 1v to the load 5.

  Of course, when there is almost no difference between the power supply recognition output frequency Fge and the current output frequency Fnow, the frequency detection unit 120 may be omitted and the power supply recognition output frequency Fge may be input to the T parameter acquisition unit 130.

  On the other hand, the position detection unit 40 detects the current position of the movable part of the variable capacitor 21, outputs the current position information as Now, and sends it to the T parameter acquisition unit 130.

The T parameter acquisition unit 130 receives the current position information Cnow output from the position detection unit 40 and the current output frequency Fnow output from the frequency detection unit 120.
The T parameter acquisition unit 130 acquires the T parameter corresponding to the current position information Cnow and the current output frequency Fnow using the T parameter stored in the memory 70, and outputs the acquired T parameter. The output T parameter is sent to the current output reflection coefficient calculation unit 140.

  In the current output reflection coefficient calculation unit 140, the traveling wave voltage at the current output terminal 302 is based on the traveling wave voltage Vfinow at the current input terminal 301, the reflected wave voltage Vrinow, and the T parameter output from the T parameter acquisition unit 130. Vfonow and reflected wave voltage Vronow are calculated. In this case, the traveling wave voltage Vfonow and the reflected wave voltage Vronow at the current output terminal 302 are calculated by the following “Equation 8”.

  In “Equation 8”, T11now, T12now, T21now, and T22now are elements constituting the T parameter output from the T parameter acquisition unit 130. That is, each element of the T parameter corresponding to the current position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power source 1v is shown.

  Further, the current output reflection coefficient computing unit 140 divides the reflected wave voltage Vronow at the current output terminal 302 by the traveling wave voltage Vfonow as shown in “Equation 9”, thereby reflecting the reflection coefficient Γoutnow at the current output terminal 302. (Hereinafter, the output reflection coefficient Γoutnow) is calculated. The calculation result is sent to the approximate reflection coefficient search unit 180.

  Also, the current output reflection coefficient Γoutnow can be calculated as shown in “Equation 10” using the T parameter.

  In the target input reflection coefficient setting unit 150, a target input reflection coefficient Γinset (hereinafter referred to as “target input reflection coefficient Γinset”) is set in advance. This target input reflection coefficient Γinset can be expressed by “Equation 11”. The target input reflection coefficient Γinset set by the target input reflection coefficient setting unit 150 is sent to the virtual output reflection coefficient calculation unit 160. The target input reflection coefficient Γinset may be changed at any time.

  In “Expression 11”, Zin is a target impedance, and is represented by Zin = Rin + jXin, which is the sum of the real part Rin and the imaginary part Xin. Zo is a characteristic impedance. The target input reflection coefficient Γinset may be set directly. Instead of setting the target input reflection coefficient Γinset directly, the target impedance Zin and the characteristic impedance Zo described above are set in advance. To the target input reflection coefficient Γinset may be used.

  Since the target input reflection coefficient Γinset is normally a minimum value, that is, 0 (when the target input reflection coefficient Γinset is expressed by the sum of a real part and an imaginary part, Γinset = 0 + j0), this target input reflection coefficient Γinset is set. Furthermore, when the position of the movable part of the variable capacitor 21 and the output frequency of the high-frequency power source 1v are adjusted, the reflected wave at the input terminal 301 is minimized and impedance matching can be performed. Of course, the target input reflection coefficient Γinset may be set to a value other than 0, but is set to be equal to or less than a value regarded as matched (for example, a relatively small value such as 0.05 or 0.1). Further, the desired target input reflection coefficient Γinset may be set in advance, or a setting unit for setting the target input reflection coefficient Γinset may be provided so that it can be changed as needed.

  Here, the relationship between the target input reflection coefficient Γinset, the current output reflection coefficient Γoutnow, and the T parameter is expressed as “Equation 12”. That is, when the current output reflection coefficient Γoutnow is set to the target input reflection coefficient Γinset set by the target input reflection coefficient setting unit 150, “Equation 12” is established.

  However, T11mat, T12mat, T21mat, and T22mat correspond to combination information of the position of the movable portion of the variable capacitor 21 and the output frequency of the high-frequency power source 1v that can be set to the target input reflection coefficient Γinset when the current output reflection coefficient Γoutnow. Each element of the T parameter. “Equation 12” can be obtained as follows.

  The output reflection coefficient Γoutnow can be obtained by “Equation 9” or “Equation 10”. Further, the traveling wave voltage Vfonow and the reflected wave voltage Vronow are expressed by Vfonow = T11mat · Vfinow + T12mat · Vrinow, Vronow = T21mat · Vfinow + T22mat · Vrinow (Vfinow, Vrinow is a traveling wave voltage and a reflected wave voltage at the current input terminal). Therefore, Γoutnow = (T21mat · Vfinow + T22mat · Vrinow) / (T11mat · Vfinow + T12mat · Vrinow). Here, since the input reflection coefficient Γinset = Vrinow / Vfinow, Γoutnow = [T21mat · Vfinow + T22mat · (Γinset · Vfinow)] / [T11mat · Vfinow + T12mat · (Γinset · Vfinow)] = (T21mat + T22mat · Γinset) / (T11mat + T12mat · Γinset) It becomes.

  Since “Equation 12” is satisfied as described above, when the current output reflection coefficient Γoutnow is obtained by the current output reflection coefficient calculation unit 140, T parameters (T11mat, T12mat, T21mat, T22mat) that satisfy “Equation 12” are satisfied. If possible, the input reflection coefficient Γinnow can be made the target input reflection coefficient Γinset. Therefore, a combination of the position of the movable portion of the variable capacitor 21 corresponding to the T parameter (T11mat, T12mat, T21mat, T22mat) for which “Equation 12” is satisfied and the output frequency of the high-frequency power source 1v may be searched.

  However, if the four elements of the T parameter (T11mat, T12mat, T21mat, T22mat) can be freely adjusted so that “Equation 12” holds, the T parameter (T11mat, T12mat, T21mat, T22mat) can be obtained. However, the S parameter and the T parameter represent transmission characteristics when the entire impedance adjusting device is handled as a transmission device, and each combination of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power source 1v is as follows. The four elements were measured as a set. Therefore, it is unlikely that there are T parameters (T11mat, T12mat, T21mat, T22mat) in which “Equation 12” is strictly established.

  Here, the pre-measured T parameter as shown in Table 3 or the T parameter that can be estimated by interpolation from the pre-measured T parameter is substituted into the right side of “Equation 12”, and the calculation result is the virtual output reflection coefficient Γoutnow ′. And Further, the virtual output reflection coefficient when the T parameter to be assigned to the right side of “Equation 12” is T (C, F) is represented as Γoutnow ′ (C, F). Similarly, each element of the T parameter is expressed as T11mat (C, F), T12 mat (C, F), T21 mat (C, F), T22 mat (C, F). For example, the virtual output reflection coefficient when T (1, 0) is represented as Γoutnow ′ (1, 0). The above relationship is expressed as “Equation 13”. Since there are a plurality of T (C, F), a plurality of Γoutnow ′ (C, F) are also calculated.

  Therefore, from the calculated virtual output reflection coefficient Γoutnow ′ (C, F), the virtual output reflection coefficient Γoutnow ′ (C, F) closest to the current output reflection coefficient Γoutnow (hereinafter, approximate reflection coefficient Γoutnow) (C, F)), the combination of the position of the movable portion of the variable capacitor 21 and the output frequency of the high-frequency power source 1v that is closest to the condition for satisfying “Equation 12” can be specified. As described above, since the target input reflection coefficient Γinset is set to be equal to or less than a value regarded as matched, if the approximate reflection coefficient Γoutnow ”(C, F) can be set, it can be regarded as matched.

  Therefore, the virtual output reflection coefficient calculation unit 160 calculates a virtual output reflection coefficient Γoutnow ′ (C, F) when the T parameter is T (C, F). Then, the calculated virtual output reflection coefficient Γoutnow ′ (C, F) is stored in the memory 170 in association with the combination information (C, F) of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. To go.

  Since the process of storing in the memory 170 can be performed in advance, it is preferably performed before impedance matching. By doing so, the calculation load at the time of impedance matching can be reduced. When the target input reflection coefficient Γinset is changed, the virtual output reflection coefficient calculation unit 160 again sets the virtual output reflection coefficient Γoutnow ′ (C, F) when the T parameter is T (C, F). The calculated virtual output reflection coefficient Γoutnow ′ (C, F) is stored in the memory 170 in association with the combination information (C, F) of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. It is preferable to keep it.

  The approximate reflection coefficient search unit 180 is the virtual output reflection coefficient Γoutnow ′ (C, F) stored in the memory 170 and is closest to the current output reflection coefficient Γoutnow (approximate reflection coefficient Γoutnow ”(C , F)) When searching, the search is made for the smallest absolute value between the current output reflection coefficient Γoutnow and the virtual output reflection coefficient Γoutnow ′ (C, F). do it.

  The approximate reflection coefficient Γoutnow ”(C, F) searched by the approximate reflection coefficient search unit 180 includes (associated with) the position information C of the movable part of the variable capacitor 21 and the output frequency information F of the high-frequency power source 1v. Therefore, the position of the movable part of the variable capacitor 21 corresponding to the searched approximate reflection coefficient Γoutnow ”(C, F) and the output frequency of the high-frequency power source 1v can be specified.

  If the absolute value | Γoutnow ”(C, F) | of the approximate reflection coefficient Γoutnow” (C, F) is larger than a predetermined value, for example, the position of the movable part of the variable capacitor 21 and the high-frequency power source 1v are temporarily set. After the output frequency is adjusted, a process of searching for the approximate reflection coefficient Γoutnow ”(C, F) may be performed again, or an abnormal signal may be output assuming that there is an abnormality. Good.

  As is clear from the above description, when the position of the movable portion of the variable capacitor 21 specified as described above and the output frequency of the high frequency power source 1v are set, the reflection coefficient Γin at the input end is brought closer to the target input reflection coefficient Γinset. Can do. That is, it can be brought close to the aligned state. Normally, it can be assumed to be impedance matched. For this reason, as shown below, adjustments are made to obtain the specified position of the movable portion of the variable capacitor 21 and the output frequency of the high-frequency power source 1v.

  The target position setting unit 191 sets the position of the movable part of the variable capacitor 21 specified as described above as the target position cmat (an example of target electrical characteristic information of the present invention). The target position setting unit 191 outputs target position information Cmat as a command signal to the adjustment unit 30 so that the position of the movable part of the variable capacitor 21 is adjusted (displaced) to the target position cmat. The target position information Cmat is generated in a format suitable for the adjustment unit 30. For example, it is generated as a voltage signal or a pulse signal.

  The adjustment unit 30 drives a stepping motor or the like based on the target position information Cmat to adjust (displace) the position of the movable part of the variable capacitor 21 to the target position cmat.

  The target frequency setting unit 192 sets the output frequency of the high frequency power supply 1v specified as described above as the target output frequency fmat (an example of target output frequency information of the present invention). The target frequency setting unit 192 outputs target output frequency information Fmat as a command signal to the high frequency power source 1v so that the output frequency of the high frequency power source 1v is adjusted (changed) to the target output frequency fmat. The target output frequency information Fmat is generated in a format suitable for the high frequency power supply 1v.

  The high frequency power source 1v adjusts (changes) the output frequency to the target output frequency fmat based on the target output frequency information Fmat.

Here, the target output frequency information Fmat will be supplementarily described.
As described above, when the manufacturer of the high-frequency power source 1v is different from the manufacturer of the impedance adjustment device 3, the power-recognition output frequency Fge recognized by the high-frequency power source 1v and the current detection by the frequency detection unit 120 are detected. Deviation (error) from the output frequency Fnow (the current output frequency Fnow recognized by the impedance adjustment device 3) may occur. If so, impedance matching with high accuracy cannot be performed.

  Therefore, the target output frequency fmat is not output to the high frequency power supply 1v as it is, but the difference between the target output frequency fmat and the current output frequency Fnow is calculated as shown in “Equation 21”, and the power source recognition output is calculated as the difference. A frequency obtained by adding the frequency Fge is set as target frequency information Fmat. In this way, target output frequency information Fmat that takes into account a difference (error) between the power supply recognition output frequency Fge and the current output frequency Fnow recognized by the impedance adjustment device 3 is output to the high frequency power supply 1v. Therefore, even when there is a deviation (error) between the power supply recognition output frequency Fge and the current output frequency Fnow, accurate impedance matching can be performed.

  Alternatively, as in “Expression 15”, the difference between the target output frequency fmat and the current output frequency Fnow is calculated, and the frequency of the difference is set as the target frequency information Fmat. Then, the high frequency power source 1v may be configured to calculate a frequency obtained by adding the target frequency information Fmat to the power source recognition output frequency Fge on the high frequency power source 1v side to obtain a new output frequency. Even if it does in this way, even if it is a case where the shift | offset | difference arises between the power supply recognition output frequency Fge and the present output frequency Fnow, an accurate impedance matching can be performed.

  [Second Embodiment]

  FIG. 6 is a functional block diagram of the control unit 100a in the second embodiment. From the viewpoint of function, the control unit 100a includes a vectorization unit 110, a frequency detection unit 120, a T parameter acquisition unit 130, a current output reflection coefficient calculation unit 140, a target input reflection coefficient setting unit 150, as shown in FIG. The virtual output reflection coefficient calculation unit 160a, the memory 170, the approximate reflection coefficient search unit 180, the target position setting unit 191 and the target frequency setting unit 192 are configured (the virtual output reflection coefficient calculation unit 160a is different from the first embodiment). ).

  In the first embodiment, for example, the virtual output reflection coefficient calculation unit 160 targets all characteristic parameters stored in the memory 70 (which will be described below using the T parameter) as a target. The virtual output reflection coefficient Γoutnow ′ (C, F) when C, F) is calculated. Then, the calculated virtual output reflection coefficient Γoutnow ′ (C, F) is stored in the memory 170 in association with the combination information (C, F) of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. It was.

  On the other hand, in the second embodiment, the virtual output reflection coefficient calculation unit 160a targets, for example, some T parameters stored in the memory 70, and the T parameters are T (C, F). Calculate the virtual output reflection coefficient Γoutnow ′ (C, F) at the time. Then, the calculated virtual output reflection coefficient Γoutnow ′ (C, F) is stored in the memory 170 in association with the combination information (C, F) of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. Configured as follows. This will be described below with reference to the drawings.

  FIG. 7 shows an example of the T parameter targeted by the virtual output reflection coefficient calculation unit 160a.

For example, it is assumed that the T parameter is stored in the memory 70 as shown in FIG. A black circle indicates a T parameter stored. Further, the T parameter shown in FIG. 7 is a part of the T parameter stored in the memory 70, and other T parameters are omitted. That is, as shown in Table 3, the T parameter when the position information C of the movable part of the variable capacitor 21 and the output frequency information F of the high frequency power supply 1v are combined in the range of 0 to 100 and at one interval is stored in the memory. 70, the position information C of the movable part of the variable capacitor 21 and the output frequency information F of the high frequency power supply 1v are combined in the range of 45 to 55 and at one interval in FIG. The T parameter is illustrated.
Further, the hatched range in FIG. 7, that is, the position information C of the movable part of the variable capacitor 21 and the output frequency information F of the high-frequency power source 1v are targeted for T parameters in the range of 47 to 53 (one interval), respectively. It shows that.

  The virtual output reflection coefficient calculation unit 160a targets the T parameter shown in FIG. 7, and similarly to the first embodiment, the virtual output reflection coefficient Γoutnow ′ () when the target T parameter is T (C, F). C, F) is calculated.

  Then, the calculated virtual output reflection coefficient Γoutnow ′ (C, F) is stored in the memory 170 in association with the combination information (C, F) of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. (Same as in the first embodiment).

  Since the approximate reflection coefficient search unit 180, the target position setting unit 191, the target frequency setting unit 192, and the like are the same as those in the first embodiment, the position of the movable portion of the variable capacitor 21 and the position of the variable capacitor 21 are the same as in the first embodiment. The output frequency of the high frequency power supply 1v is adjusted. The description is omitted here.

  If the absolute value | Γoutnow ”(C, F) | of the approximate reflection coefficient Γoutnow” (C, F) is larger than a predetermined value, for example, among the T parameters stored in the memory 70, 7 is calculated, and a virtual output reflection coefficient Γoutnow ′ (C, F) when the target T parameter is T (C, F) as described above is calculated. The calculated virtual output reflection coefficient Γoutnow ′ (C, F) is stored in the memory 170 in association with the combination information (C, F) of the position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v. Go. Then, the approximate reflection coefficient searching unit 180 is the closest to the current output reflection coefficient Γoutnow among the virtual output reflection coefficients Γoutnow ′ (C, F) newly stored in the memory 170 (approximate reflection coefficient Γoutnow ” (C, F)) may be searched for, since these are the same as those in the first embodiment, and detailed description thereof is omitted.

<Effects of Second Embodiment>
This is effective when the combination information of the position information C of the movable part of the variable capacitor 21 and the output frequency information F of the high frequency power supply 1v, which are expected to be impedance matched, is roughly known.
That is, since the combination information of the position information C of the movable part of the variable capacitor 21 that is expected to be impedance matched and the output frequency information F of the high frequency power supply 1v is generally known, a virtual output reflection coefficient Γoutnow ′ ( If the target is C, F), the approximate reflection coefficient search unit 180 can efficiently search for the approximate reflection coefficient Γoutnow ”(C, F). Specifically, the second is more than the first embodiment. In the embodiment, since the approximate reflection coefficient searching unit 180 requires a smaller number of searches when searching for the approximate reflection coefficient Γoutnow ”(C, F), the calculation load is small. Therefore, the second embodiment can perform processing at a higher speed than the first embodiment.

  In the above description, the combination information (C, F) of the position information C of the movable part of the variable capacitor 21 in the specific range and the output frequency information F of the high-frequency power source 1v is targeted. There may be a plurality instead of one. For example, it is effective when the combination information of the position information C of the movable part of the variable capacitor 21 and the output frequency information F of the high-frequency power source 1v, which is expected to be impedance-matched, is changed by changing the plasma process condition in the middle. is there.

  Further, the scope of the present invention is not limited to the above-described embodiment. For example, in the above embodiment, the S parameter and the T parameter are used as the characteristic parameters, but the characteristic parameters are not limited to these. For example, the parameter may be a Z parameter or a Y parameter. In this case, the above impedance matching may be performed by converting these parameters into the above T parameter.

DESCRIPTION OF SYMBOLS 1 High frequency power supply 1v Variable frequency type high frequency power supply 2 Transmission line 3 Impedance adjustment apparatus 3A Impedance adjustment apparatus 4 Load connection part 5 Load (plasma processing apparatus)
DESCRIPTION OF SYMBOLS 10 Directional coupler 20 Adjustment circuit 21 Variable capacitor 22 Impedance fixed capacitor 23 Inductor 30 Adjustment unit 40 Position detection unit 70 Memory 80 Network analyzer 100 Control unit 100a Control unit 110 Vectorization unit 120 Frequency detection unit 130 T parameter acquisition unit 140 Current output reflection coefficient calculation unit 150 Target input reflection coefficient setting unit 160 Virtual output reflection coefficient calculation unit 160a Virtual output reflection coefficient calculation unit 170 Memory 180 Approximate reflection coefficient search unit 191 Target position setting unit 192 Target frequency setting unit

Claims (9)

An impedance adjustment method for a high-frequency matching system including high-frequency power supply means for supplying high-frequency power to a load and impedance adjustment means for adjusting impedance viewed from the high-frequency power supply means to the load side,
Information combining the electrical characteristic information of the variable electrical characteristic element provided in the impedance adjusting means and the output frequency information of the high-frequency power supply means can be used as combination information, and the electrical characteristic information and the output frequency information can be taken. When all combinations are targeted, a characteristic parameter storage step that stores characteristic parameters indicating transmission characteristics of the impedance adjusting means as a whole when realizing the target combination, and stored in association with combination information;
When information that can acquire the traveling wave voltage traveling from the high-frequency power supply means to the load side and the reflected wave voltage reflected from the load side is high-frequency information, the output terminal of the high-frequency power supply means or the A high frequency information detecting step for detecting high frequency information at the input end of the impedance adjusting means;
A variable element information detecting step of detecting current electric characteristic information of the variable electric characteristic element;
A characteristic parameter acquisition step for acquiring a characteristic parameter corresponding to the combination of the current electrical characteristic information and the current output frequency information by searching among the characteristic parameters stored in the characteristic parameter storage step;
Current output reflection coefficient calculation for calculating a reflection coefficient at the current output end of the impedance adjusting means based on the high frequency information detected in the high frequency information detection step and the characteristic parameter acquired in the characteristic parameter acquisition step Process,
When it is assumed that the reflection coefficient at the input end of the impedance adjusting means is a preset target input reflection coefficient, the impedance corresponding to all or some of the characteristic parameters stored in the characteristic parameter storage step A virtual coefficient for calculating the reflection coefficient at the virtual output terminal of the adjusting means and outputting the calculated reflection coefficient at the plurality of virtual output terminals of the impedance adjusting means in association with the combination information corresponding to each of the reflection coefficients. An output reflection coefficient calculation step;
A virtual output reflection coefficient storage step for storing the reflection coefficient at a plurality of virtual output ends calculated in the virtual output reflection coefficient calculation step in association with the combination information corresponding to each of the reflection coefficients;
Approximate reflection for searching for a reflection coefficient at the virtual output end that most closely approximates the reflection coefficient at the current output end among the reflection coefficients at the virtual output end stored in the virtual output reflection coefficient storage step A coefficient search step;
Electric characteristic information associated with the reflection coefficient at the virtual output end searched in the approximate reflection coefficient searching step is set as target electric characteristic information, and the electric characteristic of the variable electric characteristic element is the electric characteristic indicated by the target electric characteristic information. A target electric characteristic setting step for outputting a command signal so as to be adjusted to the characteristic;
Output frequency information associated with the reflection coefficient at the virtual output end searched in the approximate reflection coefficient search step is set as target output frequency information, and the output frequency of the high-frequency power supply means is set to the frequency indicated by the target output frequency information. A target output frequency setting step for outputting a command signal to the high-frequency power supply means to be adjusted; and
A variable electrical characteristic element adjusting step for adjusting electrical characteristics of the variable electrical characteristic element based on the command signal output from the target electrical characteristic setting step;
A method for adjusting impedance of a high-frequency matching system, comprising:   The characteristic parameter stored in the characteristic parameter storage step is a characteristic parameter measured for each combination of the target combinations or a characteristic parameter obtained by converting the measured characteristic parameter. Impedance adjustment method.   The characteristic parameter stored in the characteristic parameter storage step is another parameter estimated by calculation using the characteristic parameter measured for each partial combination of the target combination and the characteristic parameter measured for each partial combination. 2. The impedance adjustment method for a high-frequency matching system according to claim 1, wherein the characteristic parameter is a combination characteristic parameter or a characteristic parameter obtained by converting the characteristic parameter. The characteristic parameter storage step includes
A first characteristic parameter storage step of storing a characteristic parameter measured for each combination of the target combination or a characteristic parameter obtained by converting the measured characteristic parameter in association with combination information;
A second characteristic parameter storage step of storing the characteristic parameter of the estimated other combination or the characteristic parameter obtained by converting the estimated characteristic parameter of the other combination in association with combination information;
The method for adjusting impedance of a high-frequency matching system according to claim 3, comprising: The current output reflection coefficient calculation step includes:
Based on the high frequency information detected in the high frequency information detection step, the reflection coefficient at the input end is calculated, and based on the calculated reflection coefficient at the input end and the characteristic parameter acquired in the characteristic parameter acquisition step, 5. The impedance adjustment method for a high-frequency matching system according to claim 1, wherein a reflection coefficient at a current output end is calculated. Based on the high frequency information detected in the high frequency information detection step, further comprising a frequency detection step of detecting output frequency information of the high frequency power supply means,
6. The impedance adjustment method for a high-frequency matching system according to claim 1, wherein the characteristic parameter acquisition step uses the output frequency information detected in the frequency detection step as current output frequency information.   6. The impedance adjustment method for a high frequency matching system according to claim 1, wherein the characteristic parameter acquisition step uses an output frequency recognized by the high frequency power supply means as current output frequency information. .   5. The impedance adjustment method for a high-frequency matching system according to claim 2, wherein the measured characteristic parameter is an S parameter, and the converted characteristic parameter is a T parameter that can be converted from the S parameter.   The high-frequency matching system according to any one of claims 1 to 8, wherein the high-frequency information is a traveling wave voltage traveling from the high-frequency power supply means to the load side and a reflected wave voltage reflected from the load side. Impedance adjustment method.

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