JP2008157906A - Output impedance detection method and impedance sensor using this method, electric power monitor in load side connected high frequency electric source and control device for high frequency electric source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ask for, for example, an impedance in the side of a plasma device processed using generating plasma, non-50 Ω load side in the output impedance of simple configuration and with accuracy, as a first subject to be solved, and as a second subject to be solved, to provide a device capable of performing several controls on the impedance matching like monitor or the like based on the impedance obtained the above method. <P>SOLUTION: A high frequency electric source having output impedance 50 Ω, and an impedance matching device between the high frequency electric source and output impedance having non-50 Ω load are installed. Furthermore, a sensor is arranged between the high frequency electric source and the impedance matching device. In this sensor, output side impedance observed from the sensor side is obtained using a pseudo-impedance consisting of the ratio between the voltage V of the high frequency electric source (a travelling wave voltage and a reflected wave voltage) and a travelling wave current I<SB>f</SB>as a parameter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention is a device for supplying a high frequency to a load having a impedance of 50Ω using a high frequency power source having a impedance of 50Ω, for example, a plasma device processed using generated plasma. The present invention relates to a method for obtaining an impedance from a voltage) and a traveling wave current, and a sensor having this impedance.
The output impedance sensor is provided on the input side of a matching device (also called a matching unit) that performs impedance matching between the high-frequency power source and the plasma device of the load, and the voltage of the high-frequency power source and the progress The present invention relates to a power monitor that obtains traveling wave power and reflected wave power from wave current.
Furthermore, the present invention relates to a control device that provides a sensor for the output impedance on the output side of a high frequency power supply and obtains traveling wave power and reflected wave power from the voltage and the traveling wave current to control and protect the output of the high frequency power supply.

  Conventionally, an impedance matching device is provided between the high-frequency power source and the load, and the traveling wave voltage and reflected wave voltage, information on the variable value of the variable capacitor obtained by measuring in advance, and this information The voltage of the traveling wave and the voltage of the reflected wave at the output terminal and the input reflection coefficient Γi at the input terminal are calculated on the basis of the T parameter of the impedance matching device corresponding to. Then, the absolute value | Γi | of the input reflection coefficient with respect to the variable value of the variable capacitor is pruned, and the impedance is matched based on this.

According to the prior art, the load-side impedance cannot be accurately obtained with a simple configuration. The same applies to the power monitor, and it was difficult to control and protect the output of the high-frequency power supply.
JP 2006-166212 “Impedance matching device”

  The present invention has been invented in view of these disadvantages of the prior art, and the first problem is that the impedance on the load side having a non-impedance impedance of 50 Ω, for example, the plasma apparatus side to be processed using generated plasma is simplified. The second problem is to provide a device capable of performing various controls related to impedance matching such as a monitor based on the output impedance thus obtained.

The main feature of the present invention is that the impedance is obtained using a parameter called pseudo-impedance S (= V / I _f ) by paying attention to the voltage V (traveling wave voltage and reflected wave voltage) and traveling wave current _If of the high frequency power source. And

Since the present invention uses the parameter of the pseudo impedance S (= V / I _f ), the output impedance can be accurately obtained with a simple configuration. Based on this, an accurate power monitor can be obtained, and the high frequency power supply can be easily controlled and protected.

The eye of the present invention is to obtain the output impedance from the voltage V applied by the high frequency power source and the traveling wave current _If as described above, and various preferred embodiments of the present invention will be described in detail below.

One embodiment of the circuit configuration embodied for carrying out this method will be described in detail.
Referring to FIG. 1, 1 is a high-frequency power source that outputs, for example, a high frequency of 13.5 MH, 2 is a sensor for obtaining impedance connected to the high-frequency power source 1, and 3 is an impedance matching device (3) connected to the sensor 2 (Also referred to as a matching unit) 4 is a load and has a non-impedance impedance of 50Ω, for example, a plasma device that uses generated plasma, and 5 is a voltage V (including traveling wave voltage and reflected wave voltage) applied by the high-frequency power source 1. ) And the traveling wave current _If , the impedance calculation circuit 6 obtains the impedance Z, 6 is an impedance control circuit, and determines whether the impedance Z obtained by the impedance calculation circuit 5 is 50Ω, and if there is a difference, the output terminal 18 The impedance is adjusted so that the impedance Z seen from the load 4 side becomes 50Ω. The combined device 3 is controlled and adjusted. Thereby, it is possible to avoid the influence of the current / voltage of the reflected wave from the load 4 side on the high frequency power source 1 side.

The configuration of the sensor 2 will be described in detail with reference to FIG.
Reference numeral 7 denotes an input terminal on the high-frequency power source 1 side, and 8 denotes a current detection unit for extracting a traveling wave current If. The current detection unit includes a toroidal core 9 and an output coil 10. A resistor R1 and an inductance L1 are connected to terminals T1 and T2 of the coil 10. At both ends of the inductance L1, a voltage obtained by multiplying the current (traveling wave current I _f -reflected wave current I _r ) by a coefficient β determined by the number of turns of the coil 10 appears. A voltage V (traveling wave voltage V _f −reflected wave voltage V _r ) multiplied by a coefficient α determined by the capacitors 12A and 12B appears at the output terminal 13. Of the voltage at the output end 11, the voltage due to the reflected wave (is the voltage at the output end 13 added to the voltage at both ends of the inductance L 1, so the voltage due to the reflected wave among the voltage at the inductance L 1. setting the voltage (beta I _r) and the number of turns and the capacitor 12A of the coil 9 so as to just cancel the voltage (alpha] V _r) resulting from the reflected wave, the value of 12B, the the output terminal 11 proportional to the traveling wave current I _f As a result of dividing the voltage by the resistors 14 and 15, a voltage Vf proportional to the traveling wave current _If appears at the output terminal 16. 17 is a voltage detection circuit, and 19 is connected to the impedance matching device 3. The output terminal is connected to the high frequency line 20. The voltage 21 is divided by the capacitor 21 and the resistor 22, and the divided output terminal 23 is connected to the output terminal 1. A divided voltage output is generated by dividing the voltage V of 9 (= traveling wave voltage V _f and reflected wave voltage V _r ) Note that the capacitors 18 and 25 are adjusted so that the characteristic impedance of the sensor (2) is 50Ω. Is to do.

Hereinafter, a method for obtaining the impedance accurately with a simple configuration by using the parameter V / I _f , that is, the pseudo-impedance S (= V / I _f ) will be described.

The traveling wave voltage is V _f , the reflected wave voltage is V _r , and the reflection coefficient is Γ.

Formula 1

Solve this for Z.

Formula 2

Thus, the impedance Z can be easily obtained from the pseudo-impedance S (= V / I _f ).
That is, the voltage V and the traveling wave current If applied by the high frequency power source 1 can be obtained as parameters, and there is no need to measure the reflected wave current. Therefore, the configuration is simple.

Furthermore, while the impedance Z exists somewhere in the infinite area of the right half of the complex plane, the pseudo-impedance S (= V / I _f ) exists in the limited area of the complex plane. The pseudo-impedance S (= V / I _f ) can be accurately measured, and the impedance value obtained from the pseudo-impedance S (= V / I _f ) is reliable.

When expressed by pseudo-impedance S, it can be easily understood from Equation 1 as shown below. Z represents the desired output impedance.

Formula 4

The region where the output impedance Z exists is limited to the right half of the complex plane. Complex of complex number C
It can be expressed by the following formula.

Formula 5

It can be understood from the following equation that the pseudo-impedance S (= V / I _f ) is limited to a circular area having a radius of 50 with the point (50, 0) on the real axis as the center. If the inequality of Expression 5 is established, it can be expressed by the following expression.

Formula 6

FIG. 4 illustrates a range in which the pseudo impedance S (= V / I _f ) exists. 45 is the center point (50, 0) of the circular area where the pseudo-impedance S (= V / I _f ) exists, and is on the real axis 41. The fact that the real part of the center point 45 is 50 is because the characteristic impedance of the coaxial cable used for transmitting power from the high-frequency power source 1 is 50Ω. Reference numeral 46 denotes a point where the absolute value of the pseudo-impedance S (= V / I _f ) is maximized, and is a point (100, 0) in which a value obtained by adding a radius 50 to the value 50 of the central real part is the real part. (The radius is 50 for the same reason that the real part of the center point 45 is 50). Reference numeral 42 denotes the position of the pseudo-impedance S (= V / I _f ) when a certain detection is made. 43 is the absolute value (| V / I _f |) of the detected pseudo-impedance S (= V / I _f ), and 44 is the phase angle of the pseudo-impedance S with respect to the real axis 41 (arg (V / I _{f f} )).

  From this figure, it is clear that the following equation holds.

Formula 7

Although it is difficult to measure the impedance Z that exists somewhere in the infinite range of the right half of the complex plane, the pseudo-impedance S (= V / I _f ) is mathematically in a limited range. It can be measured easily and accurately. Therefore, the impedance value obtained from the pseudo-impedance S (= V / I _f ) is reliable.

In this embodiment, the sensor 3 is provided at the input end of the impedance matching device, and the traveling wave power _Pf and the reflected wave power _Pr are calculated from the voltage V of the high frequency power supply 1 and the traveling wave current If and obtained. One monitoring example will be described in detail below.

As shown in FIG. 3, for example, 1 is a high-frequency power source that outputs a high frequency of 13.5 MH, 2 is a sensor 3 is a matching device (also referred to as a matching unit) provided with this sensor 2 at the input end, and 4 is a load. is there. The sensor 2 is the same as described above. 31 is a power calculation circuit comprising means for calculating the output impedance from the voltage V of the high frequency power source 1 detected from the output terminals 18 and 25 of the sensor 2 and the traveling wave current _If and means for calculating the power.

When the traveling wave voltage and current are expressed as V _{f and} I _f , and the reflected wave voltage and current are expressed as V _r and I _r , the traveling wave power P _f and the reflected wave power P _r are calculated as follows. it can.
Where Γ is the reflection coefficient described above. It can be calculated from the impedance Z by the following equation.

Formula 8

In this embodiment, the sensor 2 is provided at the output end of the high-frequency power source 1, and the output terminal 18 of the sensor 2 is directly connected to the load 4. Seeking a forward power P _f and reflected power P _r by the power calculation circuit 31 from the same manner as in Example 2 with the voltage V of the high frequency power source 1 traveling wave current I _f, and inputs these to the protection control circuit 51 Yes.
The high frequency power source 1 supplies a constant power to the load. If the traveling wave power P _f is greater than a certain value, the protection control circuit 51 adjusts the power supplied from the high frequency power supply 1 to a predetermined level by lowering the power. The reflected power P _r, larger the value is compared to a fixed value, so adverse effects such as for fault high frequency power source 1 is controlled so as to avoid lowering the supply power of the high frequency power source 1.

As described above, the first feature of the present invention is that an impedance matching device is provided between a high-frequency power source with an output impedance of 50Ω, a load with a non-50Ω impedance and the high-frequency power source, and a sensor is provided at the output end of the high-frequency power source. In this sensor, impedance detection for obtaining the impedance on the output side as viewed from the sensor using the pseudo impedance (V / I _f ), which is the ratio of the voltage of the high frequency power supply (traveling wave voltage and reflected wave voltage) and traveling wave current, as a parameter Is in the way.

    According to a second feature of the present invention, there is an impedance detection method characterized in that if the impedance value is not 50Ω, the impedance matching device is controlled so as to have an impedance of 50Ω via an impedance control circuit.

The third feature is that the sensor is provided at the output end of the high-frequency power source, and the sensor determines the impedance on the output side viewed from the sensor using the pseudo-impedance (V / I _f ) as a parameter. In the impedance detection method, the traveling wave power and the reflected power are obtained.

  The fourth feature is an impedance detection method characterized in that the traveling wave power and the reflected power of the high frequency power source are obtained, and the high frequency power source is controlled via a control circuit if each exceeds a predetermined value.

A fifth feature is that the sensor includes a high-frequency power source and the impedance matching device connected by a coaxial cable, and includes current extraction means for obtaining a traveling wave current of the high-frequency power source from the coaxial cable, and the high-frequency power source from the coaxial cable. There is an impedance detection method in which a voltage is obtained and the impedance on the output side viewed from the sensor is obtained using the pseudo impedance (V / I _f ) which is the ratio of this voltage and the traveling wave current as a parameter.

The sixth feature is a device comprising a high-frequency power source having an impedance of 50Ω, a sensor connected to the output terminal of the high-frequency power source, and an impedance matching device for interposing impedance between the sensor and a load having a non-impedance of 50Ω. In the sensor, the impedance is obtained using the pseudo impedance (V / I _f ) as a parameter, and the impedance matching device is controlled based on the obtained impedance.

    A seventh feature is a sensor characterized in that, if the impedance value is not 50Ω, the impedance matching device is controlled so that the impedance becomes 50Ω via an impedance control circuit.

The eighth feature is a device comprising a high-frequency power source with an impedance of 50Ω, a sensor connected to the output terminal of the high-frequency power source, and an impedance matching device for interposing impedance between the sensor and a load having a non-impedance of 50Ω. The power calculation circuit is connected to the sensor, the impedance is obtained by using the pseudo impedance (V / I _f ) as a parameter in the power calculation circuit, and the traveling wave power and the reflected wave power are obtained from the impedance. In the power monitor.

  The ninth feature is a device comprising: a high frequency power source having an impedance of 50Ω; a sensor connected to the output terminal of the high frequency power source; and an impedance matching device for interposing impedance between the sensor and a load having a non-impedance of 50Ω. A power calculation circuit is connected to the sensor, a control circuit is connected to the power calculation circuit, and traveling wave power and reflected wave power are obtained from the impedance obtained using the pseudo-impedance as a parameter in the power calculation circuit. The control circuit of the high frequency power supply is characterized in that the control circuit controls the high frequency power supply based on wave power and reflected wave power.

  According to a tenth feature, in the sensor, the high-frequency power source and the impedance matching device are connected by a coaxial cable, and include a current extraction unit that obtains a traveling wave current of the high-frequency power source from the coaxial cable. A sensor, a power monitor, or a high-frequency power supply control device obtains an output-side impedance viewed from the sensor using a pseudo-impedance that is a ratio of the voltage and the traveling wave current as a parameter.

According to the present invention, the impedance of the load of the high frequency power supply 1 can be accurately obtained with a simple configuration by taking into account the voltage V of the high frequency power supply 1 and the traveling wave current _If and using V / _If as a parameter. it can. It becomes easy to accurately detect the parameter V / _If . Therefore, the impedance can be accurately obtained from the parameter V / _If . The impedance matching device can be appropriately controlled.

High frequency power source 1 of the output of the V / I _f can be accurately monitored seek reflected power P _r and forward power P _f supplied from the high frequency power source 1 to the load 4 by providing a sensor 2 which is a parameter.

  Since the traveling wave power Pf and the reflected wave power Pr are obtained and compared with a predetermined value, the power supplied to the high frequency power source 1 is controlled, so that the high frequency power source 1 can be protected from output control and failure.

It is a whole block diagram of one Example of this invention. (Example 1) It is a circuit block diagram of the sensor of one Example of this invention. (Example 1) It is a whole block diagram of the electric power monitor of other one Example of this invention. (Example 2) It is a figure explaining the area where the impedance detected using the pseudo impedance concerning this invention exists. It is a whole block diagram of controlling the high frequency power supply of other one Example of this invention. (Example 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High frequency power supply 2 Sensor 3 Impedance matching apparatus 4 Load 5 Impedance calculation circuit 6 Impedance control circuit 8 Current detection part 16 Output terminal 17 Voltage detection circuit 23 Output terminal

Claims (10)

An impedance matching device is provided between the high-frequency power source having an output impedance of 50Ω and the non-50Ω load of the high-frequency power source, and a sensor is provided at the output terminal of the high-frequency power source. Impedance detection method that obtains the impedance on the output side viewed from the sensor using the pseudo impedance, which is the ratio of the voltage (traveling wave voltage and reflected wave voltage) and traveling wave current, as a parameter. 2. The impedance detection method according to claim 1, wherein if the impedance value is not 50Ω, the impedance matching device is controlled to have an impedance of 50Ω via an impedance control circuit. The sensor is provided at the output end of the high-frequency power source, and the sensor calculates the impedance on the output side viewed from the sensor using the pseudo-impedance as a parameter, and the traveling wave power and reflected power of the high-frequency power source are obtained from the obtained impedance. 3. The impedance detection method according to claim 1, wherein the impedance is detected. 4. The impedance detection method according to claim 3, wherein a traveling wave power and a reflected power of the high frequency power source are obtained, and the high frequency power source is controlled via a control circuit if each exceeds a predetermined value. The sensor includes a high-frequency power source and the impedance matching circuit connected by a coaxial cable, and includes current extraction means for obtaining a traveling wave current of the high-frequency power source from the coaxial cable, and obtains a voltage of the high-frequency power source from the coaxial cable. 5. The impedance detection method according to claim 1, wherein the impedance on the output side viewed from the sensor is obtained by using a pseudo impedance which is a ratio of the voltage and the traveling wave current as a parameter. In a device comprising a high-frequency power source having an impedance of 50Ω, a sensor connected to the output terminal of the high-frequency power source, and an impedance matching circuit for matching impedance by interposing between the sensor and a load having a non-impedance of 50Ω, A sensor characterized in that the impedance is obtained using as a parameter. The sensor according to claim 6, wherein if the impedance value is not 50Ω, the impedance matching device is controlled to have an impedance of 50Ω through an impedance control circuit. In an apparatus comprising a high-frequency power source with an impedance of 50Ω, a sensor connected to the output terminal of the high-frequency power source, and an impedance matching circuit for matching impedance by interposing between the sensor and a load having a non-impedance of 50Ω, A power monitor characterized by connecting a power calculation circuit, obtaining an impedance using the pseudo-impedance as a parameter in the power calculation circuit, and obtaining a traveling wave power and a reflected wave power from the impedance. In an apparatus comprising a high-frequency power source with an impedance of 50Ω, a sensor connected to the output terminal of the high-frequency power source, and an impedance matching circuit for matching impedance by interposing between the sensor and a load having a non-impedance of 50Ω, A power calculation circuit is connected, a control circuit is connected to the power calculation circuit, traveling wave power and reflected wave power are obtained from the impedance obtained by using the pseudo impedance as a parameter in the power calculation circuit, and the traveling wave power and reflected wave are obtained. A control apparatus for a high frequency power supply, wherein the control circuit controls the high frequency power supply based on electric power. The sensor is connected to a high-frequency power source and the impedance matching circuit through a coaxial cable, and includes a current extraction unit that obtains a traveling wave current of the high-frequency power source from the coaxial cable, and obtains a voltage from the high-frequency power source from the coaxial cable. 9. The sensor according to claim 6 or 7, or the power monitor according to claim 8, wherein the impedance on the output side viewed from the sensor is obtained using a pseudo impedance which is a ratio of the voltage and the traveling wave current as a parameter. Or the control apparatus of the high frequency power supply of Claim 9.