JP2017073772A - High frequency matching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that when an impedance adjustment device is applied to a high frequency power supply system, it is required for an impedance adjustment device to give the output frequency information for a high frequency power supply 1v, but there is a risk that a deviation (error) may occurs in the frequencies recognized by both of them, and thereby accurate impedance matching is impossible.SOLUTION: Based on the information of detected output frequency of a high frequency power supply 1v, and the like, a target information specification unit 180 specifies the positional information C of a variable capacitor 21, where the reflection coefficient at the input end approaches a preset target input reflection coefficient, and the output frequency information F of the high frequency power supply 1v. A target frequency setting unit 192 sets the target frequency information Fmat (target output frequency fmat-output frequency at the present moment Fnow+power supply recognition output frequency Fge) and outputs to the high frequency power supply 1v.SELECTED DRAWING: Figure 6

Description

  The present invention relates to 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.

  Even if it is assumed that there is an impedance adjusting device that can be applied to a high-frequency power supply system using a variable-frequency high-frequency power source 1v, the following problems are considered to occur.

[Possible issues]
In the case of an impedance adjusting device that can be applied to a high-frequency power supply system, the impedance adjusting device needs to give information for changing the output frequency to the high-frequency power source 1v (need to output a command signal). For this reason, it is necessary to minimize the deviation (error) between the output frequency recognized by the impedance adjusting device and the output frequency recognized by the high-frequency power source 1v.

  If the manufacturer of the high frequency power supply 1v and the manufacturer of the impedance adjusting device are the same, the above error can be made as small as possible. However, if the manufacturer of the impedance adjusting device is different from the manufacturer of the high-frequency power supply 1v, there is a possibility that a deviation (error) occurs. Then, accurate impedance matching cannot be performed.

  The present invention has been conceived under the above circumstances, and the output recognized by the high frequency power supply 1v when the impedance adjusting device is applied to the high frequency power supply system using the variable frequency high frequency power supply 1v. To provide a high-frequency matching system in which an impedance adjustment device can provide information on an appropriate output frequency to the high-frequency power source 1v even if there is a deviation (error) between the frequency and the output frequency recognized by the impedance adjustment device. It is aimed.

The high-frequency matching system provided by the first invention is
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,
High-frequency information detecting means for detecting high-frequency information at the input end of the impedance adjusting means;
Variable element information detecting means for detecting current electric characteristic information of a variable electric characteristic element provided inside the impedance adjusting means;
Frequency detection means for detecting the current output frequency of the high-frequency power supply means;
The electric characteristic information of the variable electric characteristic element is the current electric characteristic information of the variable electric characteristic element detected by the variable element information detecting means, and the output frequency of the high frequency power supply means is detected by the frequency detecting means. When the current output frequency (Fnow) of the high-frequency power supply means is present, the electrical characteristic information of the variable electrical characteristic element, the reflection coefficient at the input end of the impedance adjustment means approaching a preset target input reflection coefficient, and the Specifying means for specifying output frequency information (Fz) of the high-frequency power supply means;
The target electrical property information specified by the specifying means is set as target electrical property information, and a target signal is output so that the electrical property of the variable electrical property element is adjusted to the electrical property indicated by the target electrical property information. Characteristic setting means;
Variable electric characteristic element adjusting means for adjusting electric characteristics of the variable electric characteristic element based on a command signal output from the target electric characteristic setting means;
The output frequency recognized by the high frequency power supply means is input as a power supply recognition output frequency (Fge), and the current output frequency (Fnow) of the high frequency power supply means detected by the frequency detection means and specified by the specifying means The output frequency information (Fz) is input, the frequency indicated by the output frequency information (Fz) specified by the specifying means is set as the target output frequency (fmat), and the output frequency of the high-frequency power supply means is the target output frequency. A frequency obtained by calculating a difference (fmat−Fnow) between the target output frequency (fmat) and the current output frequency (Fnow) so as to be adjusted to (fmat), and adding the power source recognition output frequency (Fge) to the difference. Target output frequency setting means for outputting (fmat−Fnow + Fge) as target output frequency information (Fmat) to the high-frequency power supply means;
It is characterized by having.

The high-frequency matching system provided by the second invention is
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,
High-frequency information detecting means for detecting high-frequency information at the input end of the impedance adjusting means;
Variable element information detecting means for detecting electrical characteristic information of the current variable electrical characteristic element;
Frequency detection means for detecting the current output frequency of the high-frequency power supply means;
The electric characteristic information of the variable electric characteristic element is the current electric characteristic information of the variable electric characteristic element detected by the variable element information detecting means, and the output frequency of the high frequency power supply means is detected by the frequency detecting means. When the current output frequency (Fnow) of the high-frequency power supply means is present, the electrical characteristic information of the variable electrical characteristic element, the reflection coefficient at the input end of the impedance adjustment means approaching a preset target input reflection coefficient, and the Specifying means for specifying output frequency information (Fz) of the high-frequency power supply means;
The target electrical property information specified by the specifying means is set as target electrical property information, and a target signal is output so that the electrical property of the variable electrical property element is adjusted to the electrical property indicated by the target electrical property information. Characteristic setting means;
Variable electric characteristic element adjusting means for adjusting electric characteristics of the variable electric characteristic element based on a command signal output from the target electric characteristic setting means;
The current output frequency (Fnow) of the high frequency power supply means detected by the frequency detection means and the output frequency information (Fz) specified by the specifying means are input, and the output frequency information (Fz) specified by the specifying means is The target output frequency (fmat) and the current output frequency (Fnow) are set so that the indicated frequency is set as the target output frequency (fmat) and the output frequency of the high-frequency power supply means is adjusted to the target output frequency (fmat). A target output frequency setting means for outputting the difference frequency (fmat−Fnow) as target output frequency information (Fmat) to the high-frequency power supply means;
It is characterized by having.

The high-frequency matching system provided by the third invention is
Information combining the electrical property information of the variable electrical property element and the output frequency information of the high-frequency power supply means is combined information, and a part of all combinations that the electrical property information and the output frequency information can take A characteristic parameter indicating a transmission characteristic of the entire impedance adjusting unit when the target combination is realized, a characteristic parameter storage unit that stores the characteristic parameter in association with the combination information,
A characteristic parameter corresponding to the combination of the current electrical characteristic information and the current output frequency information is obtained by searching from the characteristic parameters stored in the characteristic parameter storage means, or obtained by an interpolation operation. Characteristic parameter acquisition means;
Current output reflection coefficient calculating means for calculating a reflection coefficient at the current output end of the impedance adjusting means based on the high frequency information detected by the high frequency information detecting means and the characteristic parameter acquired by the characteristic parameter acquiring means. When,
Further comprising
The specifying means includes a reflection coefficient at the current output end calculated by the current output reflection coefficient calculation means, a preset target input reflection coefficient, and a plurality of characteristic parameters stored in the characteristic parameter storage means. Based on the above, among all the combinations of the electrical characteristic information of the variable electrical characteristic element and the output frequency information of the high-frequency power supply means, the reflection coefficient at the output end of the impedance adjustment means is brought close to the target input reflection coefficient. It is characterized by specifying target combination information.

The high-frequency matching system provided by the fourth invention is
The characteristic parameter stored in the characteristic parameter storage means is a characteristic parameter measured for each combination of the target combinations or a characteristic parameter obtained by converting the measured characteristic parameter.

The high-frequency matching system provided by the fifth invention is
The characteristic parameter stored in the characteristic parameter storage means is another characteristic 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.

The high-frequency matching system provided by the sixth invention is
The electrical characteristic information and the output frequency information relate to some combinations of all possible combinations, and the some combinations are:
When the electrical characteristic information of the plurality of variable electrical characteristic elements is represented on a first axis, the output frequency information of the high-frequency power supply means is represented on a second axis, and the combination information of both is represented in a coordinate format, It is a combination set in a lattice shape by combining the coordinates set for each first predetermined interval on the first axis and the coordinates set for each second predetermined interval on the second axis. It is characterized by.

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

The high-frequency matching system provided by the eighth invention is
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 adjusting device provided by the ninth invention relates to high frequency information, and the high frequency information is:
The traveling wave voltage travels from the high frequency power supply means to the load side and the reflected wave voltage reflects from the load side.

  According to the present invention, even if a deviation (error) occurs between the power source recognition output frequency and the current output frequency (current output frequency recognized by the impedance adjusting means), impedance adjustment that can perform impedance matching with high accuracy. Means can be provided.

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. This is an example in which the S parameter is measured in a lattice shape and the S parameter is measured for some other combination information. 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 figure which shows an example of how to change the variable used in order to specify target combination information (Cz, Fz). 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.

  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 a characteristic parameter storage unit 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.

  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).

  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 2, 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 2, 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.

Further, as shown in FIG. 4, the S parameter may be measured in a lattice shape, and the S parameter may be measured for some other combination information.
FIG. 4 shows an example in which the S parameter is measured in a lattice shape and the S parameter is measured for some other combination information. In FIG. 4, the horizontal axis represents the position information C of the movable part of the variable capacitor 21, and the vertical axis represents the output frequency information F of the high frequency power source 1v. In addition, black circles indicate S parameters measured in a lattice shape. And the example which measured S parameter about the part of the area | region A or the area | region B further is shown.

  For example, in a predetermined range based on the combination information expected to be impedance matched, the S parameter may be measured for all combination information within the range. As described above, when the S parameter is measured with respect to substantially necessary combination information, it is possible to perform impedance matching with high accuracy while suppressing an increase in the measurement man-hour and memory capacity of the S parameter.

  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. In this case, the characteristic parameters of the S parameter and the T parameter may be estimated for all combinations that are not measured, or may be estimated for some combinations of all combinations that are not measured. As described above, if the estimated S parameter and the T parameter obtained by converting the estimated S parameter are stored in the memory 70, the calculation load during impedance matching can be reduced, but a large memory capacity is required. It may be appropriately selected according to the actual situation.

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).

  Although an example in which the S parameter is interpolated is shown above, the T parameter corresponding to the unmeasured S parameter can be estimated by bilinear interpolation using the T parameter obtained by converting the measured S parameter. The interpolation calculation method is the same as in the case of the above S parameter.

  When the measured S parameter is converted into the converted T parameter, the T parameter corresponding to the S parameter of the combination information not measured can be obtained by interpolation as follows.

That is, the combination information of the position of the movable part of the variable capacitor 21 and the output frequency of the high-frequency power source 1v is expressed in a coordinate format as (C, F), and the measured S parameter (T parameter) data interval on the variable C axis. Let c0 be the data interval on the variable F-axis. For example, the data interval when the S parameter is acquired in a grid pattern as shown in FIG. 2 is 10 for both c0 and f0.
The integer part of C / c0 is nc, the decimal part is dc, the integer part of F / f0 is nf, and the decimal part is df. For example, if the position of the movable part of the variable capacitor 21 is “83” and the data interval is “10”, nc = 8 and dc = 0.3.
In this case, the parameters T11, T12, T21, and T22 constituting the T parameter obtained by converting the S parameter are expressed as "Equation 7".

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

[Measurement circuit for measuring S-parameters]
FIG. 5 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. 5, 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. 5, the network analyzer 80 changes the position of the movable part of the variable capacitor 21 in predetermined steps and changes the high-frequency frequency output from the network analyzer 80 in predetermined steps. In S, the S parameter of the impedance adjusting device 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. Further, as shown in Table 2, the procedure is for the case where the position of the movable portion of the variable capacitor 21 and the output frequency are changed at 10-step intervals.

  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, S (0,0), S (0,10),... S (0,90), S (0,100), S (10,0), S (10,10),. What is necessary is just to measure S parameter sequentially in order like S (100,90) 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. 6 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 target information specifying unit 180, the target position setting unit 191, and the target frequency setting unit 192 are configured.

  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 target information specifying unit 180 is an example of the specifying unit of the present invention, and the target position setting unit 191 is an example of the target electric characteristic setting unit of the present invention, and the target frequency. The setting unit 192 is an example of 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 “Equation 8”, 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.

  When the T parameter corresponding to the current position information Cnow and the current output frequency Fnow is stored in the memory 70, the T parameter may be acquired from the memory 70 and the acquired T parameter may be output. However, when the T parameter corresponding to the current position information Cnow and the current output frequency Fnow is not stored in the memory 70, the current parameter is calculated by interpolation using the T parameter stored in the memory 70 as described above. The T parameter corresponding to the current position information Cnow and the current output frequency Fnow may be acquired, and the acquired T parameter may be output.

  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 “Equation 9” shown below.

  In “Equation 9”, 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 calculation unit 140 divides the reflected wave voltage Vronow at the current output terminal 302 by the traveling wave voltage Vfonow as shown in “Equation 10”, 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 target information specifying unit 180.

  Also, the current output reflection coefficient Γoutnow can be calculated as shown in “Expression 11” 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 12”. The target input reflection coefficient Γinset set by the target input reflection coefficient setting unit 150 is sent to the target information specifying unit 180. The target input reflection coefficient Γinset may be changed at any time.

  In “Equation 12”, 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 13”. 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 13” 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 13” can be obtained as follows.

  The output reflection coefficient Γoutnow can be obtained by “Equation 10” or “Equation 11”. Further, the traveling wave voltage Vfonow and the reflected wave voltage Vronow are expressed by Vfonow = T11mat · Vfinow + T12mat · Vrinow and 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 13” 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) where “Equation 13” is 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 13” is satisfied and the output frequency of the high-frequency power source 1v may be searched.

  However, if the four elements (T11mat, T12mat, T21mat, T22mat) of the T parameter can be freely adjusted so that “Equation 13” 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) that exactly satisfy “Equation 13”.

  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 13”, 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 13” 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 by “Expression 14”. 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 13” 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.

However, when the T parameter for the combination of the positions of the movable parts of all the variable capacitors 21 and the output frequency of the high-frequency power supply 1v is not known, the position of the movable part of the variable capacitor 21 closest to the condition for satisfying “Equation 13”. And the combination information of the output frequency of the high frequency power supply 1v cannot be specified with high accuracy.
However, even if the T parameter (S parameter) for all combinations is not known, the position of the movable part of the variable capacitor 21 and the output of the high-frequency power supply 1v that are closest (as close as possible) to the conditions that satisfy “Equation 13” by calculation. Combination information with frequency can be specified. This specification is performed by the target information specifying unit 180.

  In the present specification, the combination information of the specified position of the movable portion of the variable capacitor 21 and the output frequency of the high frequency power supply 1v is referred to as “target combination information (Cz, Fz)”. Further, the known T parameter will be described on the assumption that the S parameter is converted when the S parameter is acquired in a lattice shape as shown in FIG. As described above, the T parameter obtained by converting the S parameter obtained by the interpolation calculation can be used as a known T parameter. Hereinafter, a procedure for specifying the target combination information (Cz, Fz) in the target information specifying unit 180 will be described.

  By substituting “Equation 7” into “Equation 13”, the relationship shown in “Equation 15” is obtained. When “Equation 7” is substituted into “Equation 13”, T11mat = T11, T12mat = T12, T21mat = T21, and T22mat = T22. These T parameters may be read from the memory 70. In addition, the current output reflection coefficient Γoutnow and the target input reflection coefficient Γinset output from the current output reflection coefficient calculation unit 140 are input to the target information specifying unit 180.

When this “Equation 15” is replaced with “Equation 16”, it becomes as shown in “Equation 17”. These can be calculated for all combinations of nc and nf only when the first time and Γinset is changed, and stored in a memory (not shown).
In “Equation 17”, A1, A2, B1, B2, C1, C2, D1, and D2 are partly omitted to simplify the notation. For example, A1 is A1 (nc, nf, Γinset).

  If this “Equation 17” is further replaced with “Equation 18”, then “Equation 19” is obtained. In “Equation 19”, A, B, C, and D are partially omitted for the sake of simplicity. For example, A is A (nc, nf, Γinset, Γoutnow).

  When this “Equation 19” is divided into a real part and an imaginary part and dc and df are obtained, an arithmetic expression shown in “Equation 20” can be obtained.

In “Equation 19”, A = Re (A) + Im (A), B = Re (B) + Im (B), C = Re (C) + Im (C), D = Re (D) + Im (D ) Because both the real and imaginary parts are 0,
Re (A) + Re (B) dc + Re (C) df + Re (D) dcdf = 0
Im (A) + Im (B) dc + Im (C) df + Im (D) dcdf = 0. for that reason,
df =-(Re (A) + Re (B) dc) / (Re (C) + Re (D) dc)
df =-(Im (A) + Im (B) dc) / (Im (C) + Im (D) dc)
It becomes. for that reason,
(Re (A) + Re (B) dc). (Im (C) + Im (D) dc) = (Re (C) + Re (D) dc). (Im (A) + Im (B) dc)
It becomes. Therefore, “Expression 20” is obtained.

  Since there is a relationship such as “Equation 15” to “Equation 20”, in all combinations of nc (the integer part of C / c0) and nf (the integer part of F / f0), dc (the decimal of C / c0) Part) and df (decimal part of C / c0). When dc and df are between 0 and 1, target combination information (Cz, Fz) is obtained as [(nc + dc) c0, (nf + df) f0]. That is, target combination information (Cz, Fz) can be specified.

  The process of specifying the target combination information (Cz, Fz) described above will be further described.

  Referring to “Equation 15” and “Equation 16”, it can be seen that T parameters having four types of elements of ncc0, (nc + 1) c0, nff0, and (nf + 1) f0 are used. That is, it can be seen that the T parameter having the above four types of elements may be used when obtaining dc and df.

For example, when (nc, nf) = (0, 0), (nc + 1, nf) = (1, 0), (nc, nf + 1) = (0, 1), (nc + 1, nf + 1) = (1, 1).
At this time, if the data interval of the known T parameter is 10, as shown in FIG. 2, T (0,0), T (10,0), T (0,10), T (10,10) These four T parameters may be used.
Similarly, when (nc, nf) = (1, 0), 4 of T (10, 0), T (20, 0), T (10, 10), T (20, 10) Two T parameters may be used.

  In this way, the value of the combination of nc and nf is sequentially changed, and dc and df may be obtained using the corresponding T parameter.

In the case where the T parameter is acquired (the measured S parameter is converted) as shown in FIG. 2, the range is nc = 0 to 10 and nf = 0 to 10. The maximum values of nc and nf are both 16. Therefore, when considered simply, it seems that the combination values of nc and nf should be sequentially changed for all combinations of nc and nf in this range. However, as described above, four combinations of nc and nf necessary for a certain combination of nc and nf are (nc, nf), (nc + 1, nf), (nc, nf + 1), (nc + 1). , Nf + 1).
That is, in order to use one large value for each of nc and nf, in order to use all combinations of nc and nf, values in the range of nc = 0 to 9 and nf = 0 to 9 are used. Can be changed.

Therefore, if the maximum value of nc is “nc _max ” and the maximum value of nf is “nf _max ”, nc is in the range of 0 to (nc _max −1), and nf is 0 to (nf _max −1). If the value is changed in the range of), dc and df can be obtained using all combinations of nc and nf.

This will be described with reference to FIG.
FIG. 7 is a diagram illustrating an example of how to change variables used for specifying target combination information (Cz, Fz).
In FIG. 7, when nc is the horizontal axis, nf is the vertical axis, and a combination of a certain nc and nf is (nc, nf), the region surrounded by the four points described above is X (nc, nf). Yes. For example, when (nc, nf) = (0, 0), (nc, nf) = (0, 0), (10, 0), (0, 10), (10, 10) The enclosed area is X (0, 0).

Therefore, for example, (nc, nf) = (0,0) → (1,0) → (2,0) (8,0) → (9,0) → (0,1) → (1 , 1) → (2,1) (8,1) → (9,1) → (0,2) → (1,2) → (2,2) (8,9) → As (9, 9), when the value is changed sequentially from the left side to the right side of the lower stage and from the lower stage to the upper stage,
X (0,0) → X (1,0) → X (2,0)... X (8,0) → X (9,0) → X (0,1) → X (1,1) → X (2, 1) ... X (8, 1) → X (9, 1) → X (0, 2) → X (1, 2) → X (2, 2) ... X (8 , 9) → X (9, 9), the region to be calculated changes, so all combinations of nc and nf are used.

That is, as described above, if the values of nc and nf are changed in the range of nc = 0 to (nc _max −1) and nf = 0 to (nf _max −1), all nc and nf The combination can be used to determine dc and df.

  Of course, how to change the values of the variables nc and nf is not limited to the above, and other changes may be made.

In addition, when dc and df are calculated | required using said numerical formula, dc and df may not become a value between 0-1. For example, in the case of (nc, nf) = (0,0), that is, when the region “X (0,0)” is targeted, dc and df may not be a value between 0 and 1. . In such a case, the target combination information (Cz, Fz) exists outside the area “X (0, 0)”.
In the case of FIG. 7, the region “X (0, 0)” means 4 of (C, F) = (0, 0), (10, 0), (0, 10), (10, 10). This is an area surrounded by dots. The same applies to other areas.

  Further, due to the influence of the detection error of the input reflection coefficient absolute value | Γinnow |, an error also occurs in dc and df. Also, the error tends to increase as the input reflection coefficient absolute value | Гinnow | increases. Therefore, in the state where the input reflection coefficient absolute value | Γinnow | is large, the accuracy of dc and df may be low. Therefore, dc and df are once obtained. Then, by adjusting the target combination information (Cz, Fz) that can be specified therefrom, the input reflection coefficient absolute value | Гinnow | is reduced, and the accuracy of the input reflection coefficient absolute value | Гinnow | is increased. Then, dc and df may be obtained again to specify the target combination information (Cz, Fz).

  In addition, there may be a case where a plurality of combinations of nc and nf where dc and df are between 0 and 1 occur. In such a case, for example, the target combination information (Cz, Fz) is specified based on the calculation result of any one of dc and df, and the position of the adjustment unit is displaced to the specified position, and then again. What is necessary is just to obtain | require dc and df and to specify target combination information (Cz, Fz).

  Further, in all combinations of nc and nf, if dc and df are not between 0 and 1, it is out of the matching range. In the case of out of the matching range, for example, the input reflection coefficient Γin is calculated in all combinations of nc and nf where dc and df are 0, and the input reflection coefficient closest to the target input reflection coefficient Γinset is calculated. The target combination information (Cz, Fz) may be determined based on nc and nf corresponding to Γin.

  In the above description, dc and df are obtained using all combinations of nc and nf. However, the present invention is not limited to this. For example, when the obtained dc and df are between 0 and 1, it stops changing the values of nc and nf, and based on the calculation results of dc and df at that time, the target combination information (Cz, Fz) may be specified.

  The identified target combination information (Cz, Fz) 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, when the position of the movable portion of the variable capacitor 21 indicated by the target combination information (Cz, Fz) and the output frequency of the high-frequency power source 1v are set, the reflection coefficient Γin at the input end can be brought close to the target input reflection coefficient Γinset. 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 22”, 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.

  The scope of the present invention is not limited to the embodiment described above. 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 Capacitor with fixed impedance 23 Inductor 30 Adjustment unit 40 Position detection unit 70 Memory 80 Network analyzer 100 Control unit 110 Vectorization unit 120 Frequency detection unit 130 T parameter acquisition unit 140 Output reflection coefficient calculation unit 150 Target input reflection coefficient setting unit 180 Target information specifying unit 191 Target position setting unit 192 Target frequency setting unit

Ninth high frequency matching system provided by the invention is related to the high frequency information, the high frequency information,
The traveling wave voltage travels from the high frequency power supply means to the load side and the reflected wave voltage reflects from the load side.

According to the present invention, even when a deviation (error) occurs between the power supply recognition output frequency and the current output frequency (current output frequency recognized by the impedance adjusting means), high-frequency matching that can perform impedance matching with high accuracy. A system can be provided.

Claims (9)

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,
High-frequency information detecting means for detecting high-frequency information at the input end of the impedance adjusting means;
Variable element information detecting means for detecting current electric characteristic information of a variable electric characteristic element provided inside the impedance adjusting means;
Frequency detection means for detecting the current output frequency of the high-frequency power supply means;
The electric characteristic information of the variable electric characteristic element is the current electric characteristic information of the variable electric characteristic element detected by the variable element information detecting means, and the output frequency of the high frequency power supply means is detected by the frequency detecting means. When the current output frequency (Fnow) of the high-frequency power supply means is present, the electrical characteristic information of the variable electrical characteristic element, the reflection coefficient at the input end of the impedance adjustment means approaching a preset target input reflection coefficient, and the Specifying means for specifying output frequency information (Fz) of the high-frequency power supply means;
The target electrical property information specified by the specifying means is set as target electrical property information, and a target signal is output so that the electrical property of the variable electrical property element is adjusted to the electrical property indicated by the target electrical property information. Characteristic setting means;
Variable electric characteristic element adjusting means for adjusting electric characteristics of the variable electric characteristic element based on a command signal output from the target electric characteristic setting means;
The output frequency recognized by the high frequency power supply means is input as a power supply recognition output frequency (Fge), and the current output frequency (Fnow) of the high frequency power supply means detected by the frequency detection means and specified by the specifying means The output frequency information (Fz) is input, the frequency indicated by the output frequency information (Fz) specified by the specifying means is set as the target output frequency (fmat), and the output frequency of the high-frequency power supply means is the target output frequency. A frequency obtained by calculating a difference (fmat−Fnow) between the target output frequency (fmat) and the current output frequency (Fnow) so as to be adjusted to (fmat), and adding the power source recognition output frequency (Fge) to the difference. Target output frequency setting means for outputting (fmat−Fnow + Fge) as target output frequency information (Fmat) to the high-frequency power supply means;
A high-frequency matching system characterized by comprising: 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,
High-frequency information detecting means for detecting high-frequency information at the input end of the impedance adjusting means;
Variable element information detecting means for detecting electrical characteristic information of the current variable electrical characteristic element;
Frequency detection means for detecting the current output frequency of the high-frequency power supply means;
The electric characteristic information of the variable electric characteristic element is the current electric characteristic information of the variable electric characteristic element detected by the variable element information detecting means, and the output frequency of the high frequency power supply means is detected by the frequency detecting means. When the current output frequency (Fnow) of the high-frequency power supply means is present, the electrical characteristic information of the variable electrical characteristic element, the reflection coefficient at the input end of the impedance adjustment means approaching a preset target input reflection coefficient, and the Specifying means for specifying output frequency information (Fz) of the high-frequency power supply means;
The target electrical property information specified by the specifying means is set as target electrical property information, and a target signal is output so that the electrical property of the variable electrical property element is adjusted to the electrical property indicated by the target electrical property information. Characteristic setting means;
Variable electric characteristic element adjusting means for adjusting electric characteristics of the variable electric characteristic element based on a command signal output from the target electric characteristic setting means;
The current output frequency (Fnow) of the high frequency power supply means detected by the frequency detection means and the output frequency information (Fz) specified by the specifying means are input, and the output frequency information (Fz) specified by the specifying means is The target output frequency (fmat) and the current output frequency (Fnow) are set so that the indicated frequency is set as the target output frequency (fmat) and the output frequency of the high-frequency power supply means is adjusted to the target output frequency (fmat). A target output frequency setting means for outputting the difference frequency (fmat−Fnow) as target output frequency information (Fmat) to the high-frequency power supply means;
A high-frequency matching system characterized by comprising: Information combining the electrical property information of the variable electrical property element and the output frequency information of the high-frequency power supply means is combined information, and a part of all combinations that the electrical property information and the output frequency information can take A characteristic parameter indicating a transmission characteristic of the entire impedance adjusting unit when the target combination is realized, a characteristic parameter storage unit that stores the characteristic parameter in association with the combination information,
A characteristic parameter corresponding to the combination of the current electrical characteristic information and the current output frequency information is obtained by searching from the characteristic parameters stored in the characteristic parameter storage means, or obtained by an interpolation operation. Characteristic parameter acquisition means;
Current output reflection coefficient calculating means for calculating a reflection coefficient at the current output end of the impedance adjusting means based on the high frequency information detected by the high frequency information detecting means and the characteristic parameter acquired by the characteristic parameter acquiring means. When,
Further comprising
The specifying means includes a reflection coefficient at the current output end calculated by the current output reflection coefficient calculation means, a preset target input reflection coefficient, and a plurality of characteristic parameters stored in the characteristic parameter storage means. Based on the above, among all the combinations of the electrical characteristic information of the variable electrical characteristic element and the output frequency information of the high-frequency power supply means, the reflection coefficient at the output end of the impedance adjustment means is brought close to the target input reflection coefficient. 3. The high frequency matching system according to claim 1, wherein target combination information is specified.   The high-frequency matching system according to claim 3, wherein the characteristic parameter stored in the characteristic parameter storage unit is a characteristic parameter measured for each combination of the target combinations or a characteristic parameter obtained by converting the measured characteristic parameter.   The characteristic parameters stored in the characteristic parameter storage means are other parameters estimated by calculation using the characteristic parameters measured for each partial combination of the target combinations and the characteristic parameters measured for each partial combination. The high-frequency matching system according to claim 3, which is a combination characteristic parameter or a characteristic parameter obtained by converting the characteristic parameter. Some combinations of all possible combinations of the electrical characteristic information and the output frequency information are:
When the electrical characteristic information of the plurality of variable electrical characteristic elements is represented on a first axis, the output frequency information of the high-frequency power supply means is represented on a second axis, and the combination information of both is represented in a coordinate format, A combination set in a lattice shape by combining coordinates set on the first axis at every first predetermined interval and coordinates set on the second axis at every second predetermined interval. Item 6. The high-frequency matching system according to any one of Items 3 to 5. The current output reflection coefficient calculating means is:
Based on the high-frequency information detected by the high-frequency information detection means, a reflection coefficient at the input end is calculated, and based on the calculated reflection coefficient at the input end and the characteristic parameter acquired by the characteristic parameter acquisition means, The high-frequency matching system according to claim 3, wherein the reflection coefficient at the current output end is calculated.   6. The high-frequency matching system according to claim 4, 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 claim 1, wherein the high-frequency information is a traveling wave voltage that travels from the high-frequency power supply unit to the load side and a reflected wave voltage that reflects from the load side.

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