JP2010108839A - High frequency power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency power supply device which precisely controls to maintain a power value of high frequency power at a set value even when a frequency of the high frequency power supplied to a load is changed. <P>SOLUTION: The high frequency power supply device includes a first and second high frequency generation parts 101, 102 for respectively generating a first and second high frequency signal, a frequency control part 104 for giving a frequency instruction to both of the high frequency generation parts so as to maintain a difference of frequencies of both of the high frequency signals constant, a power amplification part 105 for amplifying the first high frequency signal, a multiplying part 107 for multiplying a detection signal of travelling wave power and the second high frequency signal and obtaining a signal containing a frequency component of the difference of the frequencies of both of the high frequency signals, a filter 109 for extracting a difference frequency signal having the frequency component of the difference from an output of the multiplying part, and a level control part 112 for giving an amplitude instruction to the first high frequency generation part 105 so as to maintain the travelling wave power at the set value based on a result of comparison operation of a level of the difference frequency signal extracted by the filter and a set level. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high frequency power supply device that generates high frequency power to be supplied to a load such as a plasma processing apparatus.

  In order to supply electric power to a load such as a plasma processing apparatus that performs microfabrication on a semiconductor, a high frequency power supply apparatus is used. FIG. 4 shows a basic configuration of the high-frequency power supply apparatus. In FIG. 4, 1 is a high-frequency generator that generates a high-frequency signal, 2 is a power amplifier that amplifies the high-frequency signal obtained from the high-frequency generator 1, Reference numeral 3 denotes a high-frequency detection unit that demultiplexes a part of the output of the power amplification unit and outputs a traveling wave detection signal including traveling wave power information. 4 is a filter for removing unnecessary frequency components from the traveling wave detection signal obtained from the high frequency detection unit, 5 is a level detection unit for detecting the output of the filter 4 to detect the level of the traveling wave detection signal, and 6 is a level detection unit. The comparison of the level of the traveling wave detection signal detected by the unit 4 and the set level set by the level setting unit 7 is performed, and the traveling wave power output from the power amplification unit 2 is calculated based on the calculation result. It is a level control unit that controls the output level of the high frequency generator 1 so as to keep the set value.

  In this high frequency power supply device, the high frequency generation unit 3, the level detection unit 5, the level setting unit 7, and the level control unit 6 maintain the traveling wave power applied from the power amplification unit 2 to the load at a set value so as to maintain the set value. A control unit that performs ALC control (Auto Level Control) for controlling the output level of 1 is configured. This type of power supply device is disclosed in Patent Documents 1 to 3, for example.

  In this type of high-frequency power supply device, it is required that the high-frequency power has high purity (does not contain unnecessary frequency components). Therefore, various high frequency filters are arranged in each stage from the high frequency generator 1 to the output stage of the power amplifier 2 to remove unnecessary frequency components (spurious components) generated in the power amplifier. On the output side of the power amplifying unit 2, a low-pass filter is provided for removing harmonic components from the power supplied from the amplifying unit to the load. Further, an impedance matching device is provided between the output of the high-frequency power supply device and the load, and impedance matching is performed with respect to the load in a steady state, thereby preventing reflected wave power from being generated in the load. Therefore, when the load is in a steady state, the level of traveling wave power given from the power amplifier 2 to the load is kept stable, and the reflected wave power reflected by the load and returning to the high frequency power amplifier is minimum. .

  However, when starting up a load such as a plasma processing apparatus, the impedance of the load is in a non-linear state and fluctuates at a high speed. Therefore, the matching operation of the matching device cannot catch up, causing a mismatch state and reflecting the load as a node. A wave is generated. Further, inside the load, various new frequency components are generated as spurious components due to the frequency mixing effect caused by the nonlinearity, and these spurious components are superimposed on the reflected wave. The reflected wave power on which the spurious component is superimposed flows backward in the matching device, and the component (mainly the fundamental frequency component) that can pass through the low-pass filter provided on the output side of the high-frequency power amplifier is the power amplification. Return to the output stage. In this case, the power (load side power) given from the power amplification unit to the load is the power obtained by subtracting the reflected wave power from the traveling wave power detected on the output side of the power amplification unit.

  In the plasma processing apparatus, as shown in FIG. 5, two types of high frequency powers having different output frequencies may be simultaneously applied from two high frequency power supply apparatuses to the electrodes of the plasma generation apparatus. In FIG. 5, 11 is a first high-frequency power supply device, and 12 is a second high-frequency power supply device that outputs high-frequency power having a frequency lower than the output frequency of the first high-frequency power supply device. Outputs of the first high-frequency power supply device 11 and the second high-frequency power supply device 12 are supplied to a load 15 such as a plasma processing apparatus through a first matching device 13 and a second matching device 14, respectively.

  The high-frequency power given from the first high-frequency power supply device 11 to the load 5 is high-frequency power for plasma generation, and the high-frequency power given from the second high-frequency power supply device 12 to the load 15 draws ions in the plasma. This is high frequency power for bias. Usually, the frequency of the high frequency power for plasma generation has a high frequency of about several tens of MHz to several tens of MHz, and the frequency of the high frequency power for bias has a relatively low frequency of about several hundred KHz to several MHz. Yes.

  In such a system, since the impedance of the load changes in a complicated manner, impedance matching cannot be completely achieved by the impedance matching unit, and generation of a reflected wave in the load cannot be avoided. In this case, the reflected wave returning from the load to the amplification unit side of the first high-frequency power supply device 11 includes the fundamental frequency component of the second high-frequency power supply device 12 and the spurious frequency component in the vicinity thereof. Since the fundamental frequency of the second high-frequency power supply device 12 is lower than the fundamental frequency of the first high-frequency power supply device 11, the spurious component in the reflected wave from the load 15 toward the first high-frequency power supply device 11 is the first. Passes through the low-pass filter provided on the output side of the high frequency power supply device 11 and reaches the amplifying unit of the first high frequency power supply device. In addition, since the spurious component reaching the power amplification unit of the first high frequency power supply device 11 from the second high frequency power supply device 12 and the output of the first high frequency power supply device 11 are mixed, the first high frequency power supply device 11 Spurious components are also included in the traveling wave power toward the load.

  As an example, when the output frequency of the first high frequency power supply device 1 for generating plasma is 50 MHz and the output frequency of the second high frequency power supply device 2 for biasing is 2 MHz, the first high frequency power supply device 1 supplies a load. FIG. 6 and FIG. 7 schematically show the frequency spectrum in the vicinity of the fundamental frequency component (50 MHz) of the traveling wave power and the frequency spectrum in the vicinity of the fundamental frequency component (50 MHz) of the reflected wave power, respectively. In FIG. 7, the scale of the vertical axis is the same as the scale of the vertical axis of FIG. 6 for the sake of convenience, but the level of the reflected wave power is actually lower than the level of the traveling wave power.

  As described above, when the reflected wave power with the spurious component superimposed on the output side of the power amplifying unit 2 returns, the detection signal obtained from the high frequency detecting unit 3 also includes the spurious component. If a spurious component is included in the detection signal, the level detection unit cannot accurately detect the level of the traveling wave detection signal, and the ALC control of the output of the high frequency generator 1 cannot be performed accurately. For this reason, it is necessary to insert the filter 4 before the level detection unit 5 to remove spurious components from the signal input to the level detection unit 5.

  When the above reflected wave power cannot be ignored, the reflected wave returning from the load side to the power amplification unit side as well as performing control to keep the traveling wave power detected on the output side of the power amplification unit at the set value. It is also necessary to perform control to detect the power and maintain the power obtained by subtracting the reflected wave power from the traveling wave power at the set value.

  In this case, in addition to the traveling wave detection signal including information on traveling wave power supplied from the power amplifier 2 to the load, the high frequency detector 3 shown in FIG. A reflected wave detection signal including information of the reflected wave power that returns is obtained, and the reflected wave detection signal is detected by a level detection unit provided separately from the level detection unit 5 shown in FIG. Detect the signal level. In this case, the level control unit 6 compares the level obtained by subtracting the level of the reflected wave detection signal from the level of the detected traveling wave detection signal with the set level, and based on the calculation result, calculates the level from the traveling wave power. The output of the high frequency generator 1 is ALC controlled so that the power obtained by subtracting the reflected wave power is kept at the set value.

In general, the term “spurious” is often used to mean an unnecessary frequency that appears before and after the fundamental frequency and an unnecessary frequency that appears before and after each harmonic frequency. However, in this specification, for convenience of explanation. All of the unnecessary frequency components (usually components other than the fundamental frequency component) that are unnecessary as frequency components supplied to the load are called spurious components.
JP-A-5-63627 JP-A-6-6144 Japanese Patent Laid-Open No. 11-233294

  Conventional high-frequency power supply devices were configured to generate high-frequency power of a single frequency, but in recent years, it has become necessary to perform more precise processing such as etching performed by a plasma processing device, Accordingly, a high frequency power supply device that can arbitrarily change the frequency and magnitude of the high frequency power supplied to the load has been demanded. In order to meet such a requirement, it is necessary to arbitrarily change the output frequency of the high frequency generator 1 shown in FIG. 4, and even when the output frequency of the high frequency generator 1 is changed, the load It is necessary to make it possible to accurately perform control for keeping the power value of the high-frequency power applied to the set value.

  Also, the amount of reflected wave power reflected by the load and returning to the output side of the power amplifying unit differs depending on the frequency of the high frequency power, and the amount of reflected wave power is minimized by adjusting the frequency of the high frequency power. It is possible to control. Therefore, the high frequency detector 3 may detect the reflected wave power and control to change the output frequency of the high frequency generator 1 so as to minimize the detected reflected wave power. Even when such control is performed, it is necessary to be able to arbitrarily change the output frequency of the high-frequency generator 1.

  However, in the high-frequency power supply device shown in FIG. 4, when the output frequency of the high-frequency generator 1 is changed, the following problems occur.

  That is, the filter 4 provided in the previous stage of the level detection unit 5 that detects the level of the detection signal obtained from the high-frequency detection unit 3 has a characteristic that the attenuation rate varies with a change in frequency. Even if the level is the same, if the frequency changes, the output level will change. When the output level of the filter changes with the change in frequency, the level detected by the level detector 5 also changes, and the output power value of the power amplifier 2 and the signal level detected by the level detector 5 Since the correspondence relationship changes, even if the output level of the high frequency generator 1 is controlled based on the comparison calculation between the signal level detected by the level detector 5 and the set level, the power amplifier 2 gives the load to the load. The power value of the generated high frequency power cannot be kept at the set value. The deviation (deviation) from the set value of the high-frequency power increases as the frequency change width is increased. Such a problem occurs in both cases where an analog filter is used as the filter 4 and a digital filter is used.

  As described above, in the conventional high-frequency power supply device, when the output frequency of the high-frequency generator 1 is changed, the correspondence between the output of the power amplifier 2 and the signal level detected by the level detector 5 changes. However, when the variable range of the frequency is widened, there is a problem that the deviation of the output of the power amplifying unit 2 exceeds the allowable range. In particular, when high-frequency power is supplied to a plasma processing apparatus that performs semiconductor etching or the like, it is necessary to precisely control the power value of the supplied high-frequency power at a set value. In the plasma processing apparatus, since the deviation allowed when controlling the high frequency power is small, it is necessary to avoid the situation where the power value fluctuates when the frequency of the high frequency power is changed. It has not been possible to obtain a high-frequency power supply device with a variable frequency that can meet such demands.

  An object of the present invention is to provide a high-frequency power supply device that can precisely perform control to maintain the power value of the high-frequency power at a set value even when the frequency of the high-frequency power supplied to the load is changed.

In order to achieve the above object, a high frequency power supply device according to the first aspect of the present invention comprises the following elements.
(A) A first high-frequency signal and a second high-frequency signal that are configured to generate a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude-level command, and having different frequencies. First and second high-frequency generators that respectively generate.
(B) A frequency controller that gives a frequency command to the first and second high-frequency generators so as to keep the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant.
(C) A power amplifier that amplifies the first high-frequency signal.
(D) A high frequency detection unit that detects a traveling wave detection signal including information on traveling wave power from the power amplification unit toward the load.
(E) A signal including the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal by multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal. Multiplication unit to get
(F) A filter that extracts a difference frequency signal having a frequency component that is a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal from the output of the multiplication unit.
(G) A difference frequency signal level detection unit that detects the level of the difference frequency signal extracted by the filter.
(H) The first high frequency so as to compare the level detected by the difference frequency signal level detection unit with the set level and to keep the traveling wave power from the power amplification unit to the load at the set value based on the calculation result. A level control unit for giving the amplitude command to the generation unit.

  As described above, the first and second high frequency signals for generating the first and second high frequency signals having the output frequency as commanded by the frequency command and the output amplitude level as commanded by the amplitude level command, respectively. When a generator is provided and a frequency command is given to the first and second high-frequency generators so that the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal is kept constant, Regardless of how the frequency of the first high-frequency signal (the output frequency of the first high-frequency generator) is changed in order to change the frequency of the applied high-frequency power, the difference between the frequencies of both high-frequency signals is changed according to the change. Is kept constant, the frequency of the second high-frequency signal (the output frequency of the second high-frequency generator) changes.

  Further, the frequency component of the traveling wave detection signal obtained by the high-frequency detection unit has the frequency of the first high-frequency signal as a main component, but includes a spurious frequency component in addition thereto. The spurious frequency also changes according to the change in the frequency of the first high-frequency signal.

  Therefore, when the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal are multiplied by the multiplication unit, the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal, spurious A signal including the frequency component of the difference between the frequency and the frequency of the second high-frequency signal is obtained, and the frequency component of each difference has a constant frequency. Since spurious is not a single frequency, there are a plurality of frequency components that are the difference between the spurious frequency and the frequency of the second high-frequency signal.

  Because of the relationship as described above, the extraction target in the filter is the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal, and the spurious frequency and the frequency of the second high-frequency signal If the filter has a characteristic that removes the frequency component of the difference, even if the frequency of the first high-frequency signal is changed, the frequency of the extraction target is constant, so the extraction target is not affected by the frequency characteristics of the filter. .

  Therefore, when the frequency of the high-frequency power applied to the load is changed, the correspondence between the output power value of the power amplification unit and the level detected by the difference frequency signal level detection unit is prevented from changing and supplied to the load. It is possible to obtain a high-frequency power supply device that can arbitrarily change the frequency of the high-frequency power without losing any precision in controlling the power value of the high-frequency power.

The high frequency power supply device according to the invention described in claim 2 is configured by including the following elements.
(A) A first high-frequency signal and a second high-frequency signal that are configured to generate a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude-level command, and having different frequencies. First and second high-frequency generators that respectively generate.
(B) A frequency controller that gives a frequency command to the first and second high-frequency generators so as to keep the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant.
(C) A power amplifier that amplifies the first high-frequency signal.
(D) A high frequency detection unit that detects a traveling wave detection signal including information on traveling wave power from the power amplification unit toward the load.
(E) A signal including the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal by multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal. Multiplication unit to get
(F) A filter that extracts a difference frequency signal having a frequency component that is a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal from the output of the multiplication unit.
(G) A difference frequency signal level detection unit that detects the level of the difference frequency signal extracted by the filter.
(H) The level detected by the difference frequency signal level detection unit is compared with the first set level, and the traveling wave power from the power amplification unit to the load is maintained at the set value based on the calculation result. 1st level control part which gives an amplitude command to one high frequency generating part.
(I) An output level detector that detects the output level of the second high frequency generator.
(J) The second level is calculated so that the level detected by the output level detector is compared with the second set level and the output level of the second high frequency generator is maintained at a set constant value based on the calculation result. A second level control unit for giving an amplitude command to the high-frequency generation unit.

  In the above configuration, the first level control unit is the same as the level control unit in the invention described in claim 1, and the first setting level is the same as the setting level in the invention of claim 1. . In the present invention, the difference frequency signal level detection unit and the first level control unit are provided, and based on the result of the comparison operation between the level detected by the difference frequency signal level detection unit and the first set level. By giving an amplitude command to the first high-frequency generator, not only control is performed to keep the traveling wave power from the power amplifier to the load at a set value, but also an output for detecting the output level of the second high-frequency generator. A second level detection unit and a second high frequency generation unit so as to keep the output level of the second high frequency generation unit at a set constant value based on a result of comparison between the level detected by the output level detection unit and the second set level. And a second level control unit for giving an amplitude command to the high-frequency generation unit to control the output level of the second high-frequency generation unit at a set constant value.

  In the high frequency power supply device according to the present invention, the detection signal obtained from the high frequency detection unit is input to the multiplication unit together with the output signal of the second high frequency generation unit, and the frequency component of the difference between the frequencies of the two input signals is input to the detection signal. If the output level of the second high-frequency generator changes when performing this multiplication, the level of the signal input to the filter from the multiplier changes, so that the output power value of the power amplifier The correspondence with the level detected by the difference frequency signal level detection unit changes, and the same problem as when the output level of the filter changes as the frequency changes occurs.

  On the other hand, when the control as described above is performed, the output level of the second high frequency generator can always be maintained at a constant level (second set level). It is possible to prevent the output of the multiplier from fluctuating due to the fluctuation of the level and changing the correspondence between the power value of the output of the power amplifier and the level detected by the difference frequency signal level detector. Therefore, according to the present invention, when the frequency of the high-frequency power applied to the load is changed, the output power value of the power amplification unit and the level detected by the difference frequency signal level detection unit due to the frequency characteristics of the filter The output of the multiplier fluctuates due to the fluctuation of the output level of the second high frequency generator and is detected by the output power value of the power amplifier and the difference frequency signal level detector. To obtain a high frequency power supply device that can change the frequency of the high frequency power without impairing the precision of the control that maintains the power value of the high frequency power at the set value. Can do.

The high-frequency power supply device according to the invention described in claim 3 is configured by including the following elements.
(A) A first high-frequency signal and a second high-frequency signal that are configured to generate a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude-level command, and having different frequencies. First and second high-frequency generators that respectively generate.
(B) A frequency controller that gives a frequency command to the first and second high-frequency generators so as to keep the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant.
(C) A power amplifier that amplifies the first high-frequency signal.
(D) ′ A high-frequency detection unit that detects a traveling wave detection signal including information on traveling wave power traveling from the power amplification unit toward the load and a reflected wave detection signal including information regarding reflected wave power traveling from the load side toward the power amplification unit.
(E) ′ includes the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal by multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal. A first multiplier for obtaining a signal.
(F) 'a first filter for extracting a first difference frequency signal having a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal from the output of the first multiplier.
(G) ′ A first difference frequency signal level detection unit for detecting the level of the first difference frequency signal extracted by the first filter.
(I) The reflected wave detection signal obtained by the high-frequency detection unit is multiplied by the second high-frequency signal, and the reflected wave detection signal is determined as a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A second multiplier for obtaining a signal including the frequency components of
(J) A second filter that extracts a second difference frequency signal having a frequency component of a difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal from the output of the second multiplication unit.
(K) A second difference frequency level detector that detects the level of the second difference frequency signal extracted by the second filter.
(L) A level obtained by subtracting the level detected by the second difference frequency signal level detection unit from the level detected by the first difference frequency signal level detection unit is compared with a set level, and based on the calculation result A level control unit that gives an amplitude command to the first high-frequency generator so as to keep the power applied from the power amplifier to the load at a set value.

  When configured as described above, the extraction targets of the first filter and the second filter are both frequency components of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. The component has a constant frequency. Therefore, even if the frequency of the first high-frequency signal is changed, the extraction target is not affected by the frequency characteristics of the filter because the extraction target frequency is constant. Therefore, regardless of the frequency of the high frequency power, the correspondence between the power value of the traveling wave power and the level detected by the first difference frequency signal level detection unit, and the power value of the reflected wave power and the second difference frequency. Since it is possible to prevent the correspondence relationship with the level detected by the signal level detection unit from being distorted, it is possible to precisely control the power value of the difference between the traveling wave power and the reflected wave power at the set value. . Therefore, according to the present invention, the precision of the control that maintains the power value of the difference between the traveling wave power given from the power amplification unit to the load and the reflected wave power returned from the load to the power amplification unit side at a set value is lost. Thus, a high frequency power supply device capable of changing the frequency of the high frequency power can be obtained.

The high frequency power supply device according to the invention described in claim 4 includes the following elements.
(A) A first high-frequency signal and a second high-frequency signal that are configured to generate a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude-level command, and having different frequencies. First and second high-frequency generators that respectively generate.
(B) A frequency control unit that gives the frequency command to the first and second high-frequency generators so that the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal is kept constant.
(C) A power amplifier that amplifies the first high-frequency signal.
(D) ′ A high-frequency detection unit that detects a traveling wave detection signal including information on traveling wave power traveling from the power amplification unit toward the load and a reflected wave detection signal including information regarding reflected wave power traveling from the load side toward the power amplification unit.
(E) ′ includes the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal by multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal. A first multiplier for obtaining a signal.
(F) 'a first filter for extracting a first difference frequency signal having a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal from the output of the first multiplier.
(G) ′ A first difference frequency signal level detection unit for detecting the level of the first difference frequency signal extracted by the first filter.
(I) A signal including the frequency component of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal by multiplying the reflected wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal. A second multiplication unit for obtaining
(J) A second filter that extracts a second difference frequency signal having a frequency component of a difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal from the output of the second multiplication unit.
(K) A second difference frequency level detector that detects the level of the second difference frequency signal extracted by the second filter.
(L) ′ A level obtained by subtracting the level detected by the second difference frequency signal level detection unit from the level detected by the first difference frequency signal level detection unit is compared with the first set level, and the calculation is performed. A first level control unit that gives an amplitude command to the first high-frequency generation unit so as to keep the power applied from the power amplification unit to the load at a set value based on the result.
(M) An output level detector that detects the output level of the second high-frequency generator.
(N) The second level is detected so that the level detected by the output level detector is compared with the second set level and the output level of the second high frequency generator is maintained at a set constant value based on the calculation result. A second level control unit for giving an amplitude command to the high-frequency generation unit.

  When configured as described above, the extraction targets of the first filter and the second filter are both frequency components of the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. The component has a constant frequency. Therefore, even if the frequency of the first high-frequency signal is changed, the extraction target is not affected by the frequency characteristics of the filter because the extraction target frequency is constant. Therefore, regardless of the frequency of the high frequency power, the correspondence between the power value of the traveling wave power and the level detected by the first difference frequency signal level detection unit, and the power value of the reflected wave power and the second difference frequency. The correspondence relationship with the level detected by the signal level detector is prevented from being distorted, and the output of the first and second multipliers fluctuates due to the fluctuation of the output level of the second high frequency generator, so that the traveling wave The correspondence between the power value of power and the level detected by the first difference frequency level detection unit and the correspondence between the power value of reflected wave power and the level detected by the second difference frequency level detection unit change. Therefore, the control for maintaining the power value of the difference between the traveling wave power and the reflected wave power at the set value can be performed precisely. Therefore, according to the present invention, the precision of the control for maintaining the power value of the difference between the traveling wave power given from the power amplifying unit to the load and the reflected wave power returning from the load to the power amplifying unit side at a set value is lost. Thus, a high frequency power supply device capable of changing the frequency of the high frequency power can be obtained.

  The invention described in claim 5 is characterized in that, in the invention described in any one of claims 1 to 4, each filter is constituted by an analog filter or a digital filter.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fourth aspects, each filter is an analog filter and a digital signal that digitally processes the output of the analog filter and extracts a difference frequency signal. It consists of a combination with a filter.

  As described above, when configuring the high-frequency power supply device according to the present invention, either an analog filter or a digital filter may be used as the filter provided between the multiplication unit and the difference frequency signal level detection unit. A combination of a filter and a digital filter may be used. If filtering is performed by the digital filter after removing the unnecessary frequency component by passing the output of the multiplier through the analog filter, the signal processing in the digital filter is facilitated.

  In the present invention, when an analog signal is input to each difference frequency signal level detection unit, each difference frequency signal level detection unit may be configured by an analog detector. Each difference frequency signal level detection unit may be configured to digitally process the difference frequency signal and obtain an average value or an effective value thereof. If each differential frequency signal level is detected digitally, the time constant is small compared to the case where an analog detector with a large time constant is used. Can be increased.

  In the invention described in claims 1 to 6, it is preferable that the frequency control unit is configured to simultaneously give a frequency command to the first and second high frequency generators.

  As described above, if the frequency control unit is configured so that the frequency command is simultaneously given to the first and second high frequency generation units, it is possible to reliably prevent the difference frequency from changing when the frequency of the high frequency power is changed. The frequency can be changed without causing the possibility of disturbing the control for maintaining the power value of the high-frequency power at the set value.

  According to the first aspect of the present invention, the first and second high-frequency signals having the output frequency as commanded by the frequency command and the output amplitude level as commanded by the amplitude level command are respectively generated. First and second high frequency generators are provided, and a frequency command is issued to the first and second high frequency generators so as to keep the difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal constant. As a result, no matter how the output frequency of the first high frequency generator is changed in order to change the frequency of the high frequency power applied to the load, the power is changed when the frequency of the high frequency power applied to the load is changed. The correspondence between the power value of the output of the amplifier and the level detected by the difference frequency signal level detector is prevented from changing, and the precision of the control of the power value of the high-frequency power supplied to the load is lost. Therefore, it is possible to obtain a high frequency power supply device capable of arbitrarily changing the frequency of the high frequency power.

  According to the second aspect of the present invention, when the frequency of the high frequency power applied to the load is changed, the output power value of the power amplification unit and the difference frequency signal level detection unit are caused by the frequency characteristics of the filter. The change in the correspondence with the detected level is prevented, and the output of the multiplication unit fluctuates due to the fluctuation of the output level of the second high frequency generator, and the power value of the output of the power amplifier and the difference frequency signal level detection High-frequency power supply that can change the frequency of high-frequency power without impairing the precision of control that keeps the power value of high-frequency power at a set value by preventing the correspondence with the level detected by the unit from changing A device can be obtained.

  According to the third aspect of the present invention, the correspondence between the power value of the traveling wave power and the level detected by the first difference frequency signal level detection unit and the reflected wave regardless of the frequency of the high frequency power. Since it is possible to prevent the correspondence between the power value of the power and the level detected by the second difference frequency signal level detection unit from being distorted, the power value of the difference between the traveling wave power and the reflected wave power is set to the set value. The control to keep can be performed precisely. Therefore, according to the present invention, the precision of the control that maintains the power value of the difference between the traveling wave power given from the power amplification unit to the load and the reflected wave power returned from the load to the power amplification unit side at a set value is lost. Thus, a high frequency power supply device capable of changing the frequency of the high frequency power can be obtained.

  According to the fourth aspect of the present invention, the correspondence between the power value of the traveling wave power and the level detected by the first difference frequency signal level detection unit and the reflected wave regardless of the frequency of the high frequency power. The correspondence between the power value of the power and the level detected by the second difference frequency signal level detection unit is prevented from being distorted, and the first and second multiplications are performed by the fluctuation of the output level of the second high frequency generation unit. The output of the unit fluctuates, and the correspondence between the power value of the traveling wave power and the level detected by the first difference frequency level detection unit and the power value of the reflected wave power and the second difference frequency level detection unit detect Therefore, it is possible to prevent the power value of the difference between the traveling wave power and the reflected wave power from being maintained at a set value precisely. Therefore, according to the present invention, the precision of the control for maintaining the power value of the difference between the traveling wave power given from the power amplifying unit to the load and the reflected wave power returning from the load to the power amplifying unit side at a set value is lost. Thus, a high frequency power supply device capable of changing the frequency of the high frequency power can be obtained.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a configuration of a first embodiment of a high-frequency power supply device according to the present invention. In the figure, reference numeral 101 denotes a first high frequency signal S1 that generates a first high frequency signal S1 having an output frequency commanded by a first frequency command Cf1 and an output amplitude level commanded by a first amplitude level command Ca1. A generating unit 102 generates a second high frequency signal S2 having an output frequency commanded by the second frequency command Cf2 and an output amplitude level commanded by the second amplitude level command Ca2. It is. In the present embodiment, the first high-frequency generator 101 and the second high-frequency generator 102 are configured by a known DDS (Direct Digital Synthesizer).

  Reference numeral 103 denotes a frequency setting unit for setting the frequency of the high-frequency power supplied to the load, and reference numeral 104 denotes a first so as to keep the difference Δf between the frequency f1 of the first high-frequency signal S1 and the frequency f2 of the second high-frequency signal S2 constant. And a frequency control unit for giving frequency commands Cf1 and Cf2 to the second high frequency generators 101 and 102, respectively.

  The frequency control unit 104 used in the present embodiment sets the frequency set by the frequency setting unit 103 as the first frequency f1, and sets the frequency having a certain difference Δf with respect to the first frequency f1 as the second frequency f2. A first frequency command Cf1 for instructing to generate a first high-frequency signal S1 having a first frequency f1, and a second for instructing to generate a second high-frequency signal S2 having a second frequency f2. Are simultaneously given to the first high frequency generator 101 and the second high frequency generator 102, respectively, so that the difference between the frequency f1 of the first high frequency signal and the frequency f2 of the second high frequency signal is always constant. The first high-frequency generator 101 and the second high-frequency generator 102 are controlled so as to keep the value Δf (= | f1-f2 |). The frequency f2 of the second high-frequency signal S2 may be lower or higher than the frequency f1 of the first high-frequency signal S1. Note that the frequency f1 of the first high-frequency signal S1 (the output frequency of the first high-frequency generator 101) matches the basic frequency of the first high-frequency power supply device 11.

  Reference numeral 105 denotes a power amplifying unit including a known power amplifying circuit, which amplifies the first high-frequency signal S1 and outputs high-frequency power applied to the load. The output of the power amplifier 105 is supplied to a load such as a plasma processing apparatus through an impedance matching device (not shown). In some cases, the impedance matching device is not used.

  Reference numeral 106 denotes a high frequency detection unit inserted between the output terminal of the power amplification unit 105 and an impedance matching device (not shown). The high-frequency detection unit is formed of, for example, a directional coupler, and demultiplexes a part of traveling wave power from the power amplification unit 105 toward the load to generate a traveling wave detection signal Sp including information on the traveling wave power. Output.

  Note that the frequency component of the traveling wave detection signal obtained by the high-frequency detection unit 106 includes the frequency f1 of the first high-frequency signal S1 as a main component, but also includes spurious frequency components. The spurious frequency also changes in accordance with the change in the frequency f1 of the first high-frequency signal S1.

  Reference numeral 107 denotes a multiplication unit to which the traveling wave detection signal Sp obtained by the high frequency detection unit and the second high frequency signal S2 output from the second high frequency generation unit 102 are input. The multiplication unit detects the traveling wave. By multiplying the signal Sp by the second high-frequency signal S2, a signal Sfp 'including the frequency component of the difference between the frequency f1 of the first high-frequency signal S1 and the frequency f2 of the second high-frequency signal S2 is output.

  As is well known, when two signals are multiplied by the multiplication unit, a signal including not only the frequency component of the frequency difference between the two signals but also the frequency component of the sum of the frequencies of the two signals is obtained. For example, in the system shown in FIG. 5, the case where the basic frequency of the first high-frequency power supply device 11 (the frequency f1 of the first high-frequency signal S1) is 50 MHz and the basic frequency of the second high-frequency power supply device 12 is 2 MHz. Then, components such as 46, 48, 52, and 54 MHz as spurious components flow into the vicinity of the fundamental frequency of 50 MHz through the output transmission system to the output terminal of the high frequency power supply device 11. In this case, when the output frequency of the second high frequency generator 102 (frequency f2 of the second high frequency signal S2) is set to 49.5 MHz and the desired difference frequency is 0.5 MHz, the difference frequency with respect to the basic frequency 50 MHz is 0.5MHz, the sum frequency is 99.5MHz. Similarly, the difference frequencies for the above spurious components are 3.5, 1.5, 2.5, and 4.5 MHz, and the sum frequencies are 95.5, 97.5, 101.5, and 103.5 MHz.

  As described above, since the difference between the frequency f1 of the first high-frequency signal S1 and the frequency f2 of the second high-frequency signal S2 is controlled to be always kept at a constant value Δf, the first high-frequency power supply device 11 is temporarily assumed. Even if the fundamental frequency (frequency f1 of the first high-frequency signal S1) changes from 50 MHz to 50.5 MHz, the difference frequency with respect to the fundamental frequency 50 MHz is constant at 0.5 MHz. Further, since the spurious frequency also changes in accordance with the change in the fundamental frequency (the frequency f1 of the first high-frequency signal S1), the difference frequency with respect to the spurious component does not change from the relationship shown above.

  Therefore, if a filter 109 that passes a component having a difference frequency of 0.5 MHz with respect to the fundamental frequency and removes a frequency component equal to or higher than the difference frequency of the spurious component (for example, having a characteristic with a cutoff frequency of 1 MHz), the difference with respect to the fundamental frequency is used. The component of frequency 0.5MHz can be extracted with high accuracy.

  That is, the extraction target in the filter 109 is the frequency component of the difference between the frequency f1 of the first high-frequency signal S1 and the frequency f2 of the second high-frequency signal S2, and the spurious frequency and the frequency f2 of the second high-frequency signal S2 If the filter has a characteristic that removes the frequency component of the difference, the frequency to be extracted is constant even if the frequency f1 of the first high-frequency signal S1 is changed. Not affected. Therefore, if the signal extracted by the filter 109 is used, the fundamental frequency component can be accurately extracted from the signal output from the high-frequency detection unit 106.

  When the fundamental frequency of the first high frequency power supply device 11 is changed from 50 MHz to 50.5 MHz, the sum frequency with respect to the fundamental frequency 50 MHz is 100.5 MHz, which is different from the relationship shown above. Further, the sum frequency for the spurious component is also different from the relationship shown above. However, since these frequency components are objects to be removed by the filter 109, they do not have an influence.

  The filter 109 is a filter that extracts a desired difference frequency signal Sfp from the output of the multiplication unit 107. This filter may consist of an analog filter (pand pass filter or low pass filter) or a digital filter.

  The difference frequency signal Sfp extracted by the filter 109 is given to the difference frequency level detection unit 110. The difference frequency level detection unit 110 is a part that detects the level of the difference frequency signal Sfp by performing analog processing or digital processing on the difference frequency signal Sfp. In the present embodiment, the difference frequency level detection unit 110 includes a detection circuit, and outputs a level detection signal Spa indicating the level of the difference frequency signal Sfp by detecting the difference frequency signal Spf.

  The level detection signal Spa obtained from the difference frequency signal level detection unit 110 is input to the first level control unit 112 together with the first level setting signal Spas output from the first level setting unit 111. The first level control unit 112 compares the level detected by the difference frequency signal level detection unit 110 with the first set level set by the first level setting unit 111, and based on the calculation result This is a portion that gives an amplitude command Ca1 to the first high-frequency generator 101 so as to keep the traveling wave power from the power amplifier 105 toward the load at a set value.

  Note that the first setting level set by the first level setting signal Spas is the first high-frequency generation unit 101 necessary for making the power value of the traveling wave power output from the power amplification unit 105 equal to the setting value. Output level.

  The first level control unit 112 may be composed of an analog circuit or a digital circuit. In the present embodiment, the first high frequency generator 101 is made of DDS, and it is necessary to give an amplitude command consisting of a digital signal from the frequency controller 104 to the first high frequency generator 101. When the unit 112 is configured by an analog circuit, it is necessary to provide an AD converter or the like on the output side of the first level control unit 112 to convert the output signal of the first level control unit 112 into a digital signal. .

  When the first level control unit 112 is configured by a digital circuit, the level detection signal Spa obtained from the difference frequency signal level detection unit 110 is given to the first level control unit 112 through an A / D converter. At this time, the first level control unit 112 calculates the level of the first high-frequency signal S1 necessary for making the level of the difference frequency signal Sfp equal to the first set level, and calculates the first level of the calculated level. An amplitude command Ca1 is given to the first high-frequency generator 101 so that the high-frequency signal S1 is generated from the first high-frequency generator 101.

  In the present embodiment, an output level detector 113 for detecting the output level of the second high frequency generator 102 is also provided, and the output signal S2a is output from the second level setting unit 114 as a second level. The signal is input to the second level controller 115 together with the setting signal S2as. The second level control unit 115 compares the output level of the second high frequency generation unit 102 detected by the output level detection unit 113 with the second set level set by the second level setting unit 114. Based on the calculation result, an amplitude command Ca2 is given to the second high-frequency generator 102 so as to keep the level of the second high-frequency signal S2 output from the second high-frequency generator 102 at the second set level. In the present embodiment, the second level control unit 115 is composed of a digital circuit, and the level detection signal S2a obtained from the output level detection unit 113 is given to the second level control unit 115 through the A / D converter. The second level control unit 115 calculates the level of the second high-frequency signal S2 necessary for making the level of the level detection signal S2a equal to the first set level, and calculates the second high-frequency signal of the calculated level. An amplitude command Ca2 is given to the second high frequency generator 102 so that S2 is generated from the second high frequency generator 102.

  In the high frequency power supply device of the present embodiment, the frequency control unit 104 has the first and second high frequency generation units so as to keep the difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal constant. Since the frequency commands Cf1 and Cf2 are given simultaneously, the difference Δf between the frequency f1 of the first high-frequency signal S1 and the frequency f2 of the second high-frequency signal S2 is always constant. The power amplifier 105 amplifies the first high-frequency signal S1 obtained from the first high-frequency generator 101 and outputs high-frequency power supplied to the load. The traveling wave power given to the load from the power amplifier 105 is detected by the high frequency detector 106. The traveling wave detection signal Sp obtained from the high frequency detection unit 106 is input to the multiplication unit 107 together with the second high frequency signal S2. The multiplier 107 multiplies the traveling wave detection signal and the second high-frequency signal S2, and the frequency component of the difference Δf (= f1-f2) between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A signal Sfp ′ including is output. The filter 109 removes a spurious component from the signal Sfp ′ to extract a difference frequency signal Sfp having a frequency component that is a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. Sfp is given to the difference frequency signal level detection unit 110. The difference frequency signal level detection unit 110 detects the level by detecting the difference frequency signal Sfp, and provides the detected level to the first level control unit 112. The first level control unit 112 compares the level detected by the difference frequency signal level detection unit 110 with the first set level set by the first level setting unit 111, and based on the calculation result Since the amplitude command Ca1 is given to the first high frequency generator 101 so that the traveling wave power from the power amplifier 105 toward the load is kept at the set value, the high frequency power given from the power amplifier 105 to the load is kept at the set value. It is.

  As described above, in the present invention, the first and second high-frequency generators 101 and 102 maintain the difference between the frequency f1 of the first high-frequency signal S1 and the frequency of the second high-frequency signal S2. Since the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal is kept constant by giving the frequency command, the first high-frequency power is changed to change the frequency of the high-frequency power applied to the load. Correspondence between the power value of the output of the power amplifier 105 and the level detected by the difference frequency signal level detector 110 when the frequency of the high frequency power applied to the load is changed even if the output frequency of the generator 101 is changed A high frequency that can prevent the relationship from changing and can arbitrarily change the frequency of the high-frequency power without losing any precision in the control of the power value of the high-frequency power supplied to the load. It can be obtained the power supply.

  Further, in the high frequency power supply device of the present embodiment, the second level control unit 115 compares the output level of the second high frequency generation unit 102 detected by the output level detection unit 113 with the second set level. In order to give an amplitude command to the second high-frequency generator 102 so as to keep the output level of the second high-frequency generator 102 (the signal level of the second high-frequency signal S2) at a set constant value based on the calculation result. The output level of the second high frequency generator can always be kept at a constant level (second set level). Therefore, the output level of the multiplication unit 108 varies due to the variation of the output level of the second high frequency generation unit, and the power value of the output of the power amplification unit 105 and the level detected by the difference frequency signal level detection unit 110 It is possible to prevent the correspondence relationship from changing.

  Therefore, according to the present embodiment, when the frequency of the high-frequency power applied to the load is changed, the output power value of the power amplifier 105 and the difference frequency signal level detector 110 are detected due to the frequency characteristics of the filter. And the difference between the output level of the power amplifying unit 105 and the difference frequency signal level detection due to the fluctuation of the output level of the second high frequency generator and the output of the multiplier The correspondence with the level detected by the unit 110 can be prevented from changing, and the control for maintaining the power value of the high-frequency power at the set value can be further improved.

  As in the above embodiment, it is desirable to control the output level of the second high-frequency power generation unit 102 to be constant, but when the expected fluctuation in the output of the second high-frequency power generation unit 102 is slight, The control system for controlling the output level of the second high-frequency power generator 102 can be omitted. Therefore, in the basic configuration of the high-frequency power supply device according to the present invention, the output level detection unit 113, the second level control unit 115, and the second level setting unit 114 of the embodiment shown in FIG. it can.

  In the above description, the first level control unit 112 is configured by a digital circuit. However, the first level control circuit 112 may be configured by an analog circuit. In this case, for example, a comparison circuit is provided in the first level control unit 112, and the level detection signal Spa output from the difference frequency signal level detection unit 110 and the first level setting by the comparison circuit are provided. The level of the first level setting signal Spas output from the unit 111 is compared. As a result of this comparison, the first level control unit 112 reduces the output level of the first high frequency generator 101 when the level of the level detection signal Spa is higher than the level of the first level setting signal Spas. An amplitude command is given to the first high frequency generator 101, and when the level of the level detection signal Spa is lower than the level of the first level setting signal Spas, the output level of the first high frequency generator 101 is increased. To the first high-frequency generator 101, the output level of the first high-frequency generator 101 is controlled to be equal to the first set level, and the output outputted from the power amplifier 106 is controlled. The power value of the wave power is converged to the set value.

  In the above description, the difference frequency signal level detection unit 110 is configured by the detection circuit. However, the difference frequency signal level detection unit 110 is configured to detect the level by digitally processing the difference frequency signal. You can also. For example, the level of the difference frequency signal is detected by sampling the difference frequency signal Spa at a constant sampling period and averaging the sample values or calculating the effective value using the sample values. Can do. Such a difference frequency level detection unit 110 can be easily configured by using a gate array such as an FPGA (Field Programmable Gate Array) that can appropriately define and change an internal logic circuit.

  In the embodiment shown in FIG. 1, when the frequency controller 104, the difference frequency signal level detector 110, the first level controller 112, the output level detector 113, and the second level controller 115 are digitized. These parts can be configured by FPGA together.

  FIG. 2 shows a second embodiment of the present invention. In this embodiment, the high frequency detector 106 includes a traveling wave detection signal Sp including information on traveling wave power from the power amplifier 105 toward the load and the load. A reflected wave detection signal Sr including information of reflected wave power directed from the side toward the power amplification unit 105 is output.

  In the embodiment shown in FIG. 2, the multiplication unit 107, the filter 109, and the difference frequency signal level detection unit 110 shown in FIG. 1 are replaced with the first multiplication unit 107, the first filter 109, and the first difference frequency signal level, respectively. In addition to the configuration shown in FIG. 1, the detection unit 110 further includes a reflected wave reference level setting unit 120, a second multiplication unit 121, a second filter 123, and a second difference frequency signal level detection. Part 124 is provided.

  The reflected wave reference level setting unit 120 is a part that sets a reflected wave reference level that gives a reference value of reflected wave power included in the power detected by the high frequency detection unit 106, and is set by the reflected wave reference level setting unit 120. The reflected wave reference level is given to the frequency control unit 104.

  The second multiplication unit 121 multiplies the reflected wave detection signal Sr obtained by the high frequency detection unit 106 and the second high frequency signal S2 output from the second high frequency generation unit 102 to obtain the first high frequency signal S1. A signal Sfr ′ containing the frequency component of the difference between the frequency f1 of the second and the frequency f2 of the second high-frequency signal S2 is output.

  The second filter 123 removes a spurious component from the output of the second multiplier 122 and has a second difference having a frequency component that is the difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. The frequency signal Sfr is extracted, and the extracted second difference frequency signal Sfr is supplied to the second difference frequency signal level detection unit 124. The second difference frequency signal level detection unit 124 detects the level of the second difference frequency signal Sfr, and provides the frequency control unit 104 with a second level detection signal Sra indicating the detected level.

  The frequency control unit 104 of this embodiment uses the level of the second difference frequency signal detected by the second difference frequency signal level detection unit 124 as the reflected wave reference level set by the reflected wave reference level setting unit 120. In comparison, when the level of the second difference frequency signal is higher than the reflected wave reference level (when the reflected wave power is higher than the reference level), the second difference frequency signal is reduced to reduce the reflected wave power. The output frequency of one high frequency generator 101 is changed.

  When control for reducing the power value of the reflected wave power is performed, for example, the frequency f1 of the first high-frequency signal S1 is changed within an extremely narrow frequency range, and the second difference frequency signal level in the frequency range is changed. The frequency f1 at which the level detected by the detection unit 124 is minimized (the reflected wave power detected on the output side of the power amplification unit is minimized) is specified. Next, a new narrow frequency range is set around the specified frequency f1, and the frequency f1 of the first high-frequency signal S1 is changed within the frequency range, and the second difference frequency signal in the frequency range is changed. The frequency f1 at which the level detected by the level detector 124 is minimized is specified. In the process of repeating such processing, when the level detected by the second difference frequency signal level detection unit 124 becomes equal to or lower than the level set by the reflected wave reference level setting unit 120, the first high frequency signal S1. Stop changing the frequency. When the level detected by the second difference frequency signal level detection unit 124 exceeds the level set by the reflected wave reference level setting unit 120, the above process is resumed.

  When the above control is performed, the reflected wave reference level when the change in the frequency f1 of the first high-frequency signal S1 is resumed is the reflected wave reference level when the change in the frequency f1 of the first high-frequency signal S1 is stopped. It is desirable to set a larger value. The reason is that if the reflected wave reference level when stopping the change of the frequency f1 and the reflected wave reference level when restarting the change of the frequency f1 are made the same, the level of the detected second difference frequency signal becomes the same. This is because a hunting state in which the control is frequently switched when a transition is made in the vicinity of the reflected wave reference level.

  By performing the control as described above, control is performed so that the power value of the reflected wave power detected on the output side of the power amplifier 105 falls within an allowable range. The frequency control unit 104 changes the frequency f1 of the first high-frequency signal S1 and the frequency f2 of the second high-frequency signal S2 in the process of changing the frequency f1 of the first high-frequency signal S1 in order to obtain the minimum value of the reflected wave power. The frequency command is simultaneously given to the first high-frequency generator 101 and the second high-frequency generator 102 so that the difference frequency Δf between the first and second high-frequency generators 102 and 102 is kept constant. Other configurations are the same as those of the embodiment shown in FIG.

  In the high frequency power supply according to the present embodiment, as described above, the frequency f1 of the first high frequency signal S1 and the second frequency are changed even when the frequency of the high frequency power is changed so that the power value of the reflected wave power falls within the allowable range. Since the frequency command is simultaneously given to the first high frequency generator 101 and the second high frequency generator 102 so that the difference Δf between the high frequency signal S2 and the frequency f2 is always kept constant, the first filter 109 and the second filter The frequency characteristics of the filter 123 can prevent the level of the difference frequency signal from fluctuating, and the correspondence and reflection between the power value of the traveling wave power and the level detected by the first difference frequency signal level detection unit 110. The control for maintaining the traveling wave power at the set value and the reflected wave power by preventing the correspondence between the power value of the wave power and the level detected by the second difference frequency signal level detection unit 124 from being distorted. It is possible to accurately perform control to stay within volume range.

  In the embodiment shown in FIG. 2, the second filter 123 may be an analog filter or a digital filter. The second filter 123 may be a combination of an analog filter and a digital filter. The second difference frequency signal level detection unit 124 may be composed of a detection circuit or a digital circuit.

  FIG. 3 shows a third embodiment of the high-frequency power supply device according to the present invention. In this embodiment, the level detection signal Sra obtained from the second difference frequency signal level detection unit 124 and the level detection signal Spa output from the second difference frequency signal level detection unit 110 are combined with the first level control unit 112. Is given to. The first level control unit 112 of the present embodiment is obtained by subtracting the level detected by the second difference frequency signal level detection unit 124 from the level detected by the first difference frequency signal level detection unit 110. The level is compared and calculated with the first set level set by the first set level setting unit 111, and the power given from the power amplification unit 105 to the load based on the calculation result (the reflected wave power is calculated from the traveling wave power). An amplitude command is given to the first high frequency generator so as to keep the subtracted power at a set value. Other configurations are the same as those of the second embodiment shown in FIG.

  When configured as in the present embodiment, regardless of the frequency of the high frequency power, the correspondence between the power value of the traveling wave power and the level detected by the first difference frequency signal level detection unit 110 and the reflected wave power The correspondence between the power value and the level detected by the second difference frequency signal level detection unit 124 is prevented from being out of order, and the first and second multiplication units are caused by fluctuations in the output level of the second high frequency generation unit. Correspondence between the power value of the traveling wave power and the level detected by the first difference frequency level detection unit and the power value of the reflected wave power and the second difference frequency level detection unit when the outputs of 108 and 122 fluctuate Therefore, it is possible to prevent the power value corresponding to the difference between the traveling wave power and the reflected wave power from being set to a precise value. Therefore, according to the present embodiment, the precision of the control for maintaining the power value of the difference between the traveling wave power given from the power amplification unit to the load and the reflected wave power returning from the load to the power amplification unit side at the set value is A high-frequency power supply device that can change the frequency of the high-frequency power without damaging it can be obtained.

  In the embodiment shown in FIG. 3, as in the embodiment shown in FIG. 2, the frequency of the high frequency power is changed so that the reflected wave power falls within the allowable range. However, the embodiment shown in FIG. Similarly, when changing the frequency of the high frequency power to meet the demand on the plasma load side, the traveling wave power given from the power amplification unit to the load and the reflected wave power returning from the load to the power amplification unit side Of course, it can be configured to perform control for keeping the power value of the difference between the two values at the set value. In that case, in FIG. 3, the second difference frequency signal level detection unit 124 and the frequency control unit 104 are disconnected, and the reflected wave reference level setting unit 120 is replaced with the frequency setting unit 103 shown in FIG.

It is the block diagram which showed the structure of the 1st Embodiment of this invention. It is the block diagram which showed the structure of the 2nd Embodiment of this invention. It is the block diagram which showed the structure of the 3rd Embodiment of this invention. It is the block diagram which showed the structure of the conventional high frequency power supply device. It is the block diagram which showed the structure of the system which supplies electric power from two high frequency power supply devices from which output frequency differs to loads, such as a plasma processing apparatus. 6 is a frequency spectrum showing an example of a frequency distribution of traveling wave power detected on the output side of the power amplifier in the system shown in FIG. 5. 6 is a frequency spectrum showing an example of a frequency distribution of reflected wave power detected on the output side of the power amplifier in the system shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 1st high frequency generation part 102 2nd high frequency generation part 103 Frequency setting part 104 Frequency control part 105 Power amplification part 106 High frequency detection part 107 Multiplication part (1st multiplication part)
109 filter (first filter)
110 Difference frequency signal level detector (first difference frequency signal level detector)
111 Second Level Setting Unit 112 First Level Control Unit 113 Output Level Detection Unit 114 Second Level Setting Unit 115 Second Level Control Unit 120 Reflected Wave Reference Level Setting Unit 121 Second Multiplying Unit 123 Second Filter 124 Second difference frequency signal level detection unit

Claims (6)

A first high-frequency signal and a second high-frequency signal having different frequencies are generated by generating a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude level command. First and second high frequency generators;
A frequency controller for giving the frequency command to the first and second high-frequency generators so as to keep a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant;
A power amplifier for amplifying the first high-frequency signal;
A high frequency detection unit for detecting a traveling wave detection signal including information on traveling wave power from the power amplification unit toward the load;
Multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal includes a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A multiplier for obtaining a signal;
A filter that extracts a difference frequency signal having a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal from the output of the multiplier;
A difference frequency signal level detection unit for detecting a level of the difference frequency signal extracted by the filter;
The first high-frequency generation is performed so that the level detected by the difference frequency signal level detection unit is compared with a set level and the traveling wave power from the power amplification unit to the load is maintained at a set value based on the calculation result. A level control unit that gives the amplitude command to the unit;
A high-frequency power supply device. A first high-frequency signal and a second high-frequency signal having different frequencies are generated by generating a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude level command. First and second high frequency generators;
A frequency controller for giving the frequency command to the first and second high-frequency generators so as to keep a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant;
A power amplifier for amplifying the first high-frequency signal;
A high frequency detection unit for detecting a traveling wave detection signal including information on traveling wave power from the power amplification unit toward the load;
Multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal includes a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A multiplier for obtaining a signal;
A filter that extracts a difference frequency signal having a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal from the output of the multiplier;
A difference frequency signal level detection unit for detecting a level of the difference frequency signal extracted by the filter;
The level detected by the difference frequency signal level detector is compared with a first set level, and the traveling wave power from the power amplifier to the load is maintained at a set value based on the calculation result. A first level control unit for giving the amplitude command to the high frequency generation unit of
An output level detector for detecting an output level of the second high frequency generator;
The level detected by the output level detection unit is compared with a second set level, and the second high frequency generation unit is maintained at a set constant value based on the calculation result. A second level control unit for giving an amplitude command to the high frequency generation unit of
A high-frequency power supply device. A first high-frequency signal and a second high-frequency signal having different frequencies are generated by generating a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude level command. First and second high frequency generators;
A frequency controller for giving the frequency command to the first and second high-frequency generators so as to keep a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant;
A power amplifier for amplifying the first high-frequency signal;
A high frequency detection unit for detecting a traveling wave detection signal including information on traveling wave power from the power amplification unit toward the load and a reflected wave detection signal including information on reflected wave power from the load side toward the power amplification unit;
Multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal includes a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A first multiplier for obtaining a signal;
A first filter for extracting a first difference frequency signal having a frequency component of a difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal from the output of the first multiplication unit;
A first difference frequency signal level detection unit for detecting a level of the first difference frequency signal extracted by the first filter;
Multiplication of the reflected wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal includes a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A second multiplier for obtaining a signal;
A second filter for extracting a second difference frequency signal having a frequency component of a difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal from the output of the second multiplication unit;
A second difference frequency level detection unit for detecting a level of the second difference frequency signal extracted by the second filter;
A level obtained by subtracting the level detected by the second difference frequency signal level detection unit from the level detected by the first difference frequency signal level detection unit is compared with a set level, and based on the calculation result, A level control unit that gives the amplitude command to the first high-frequency generation unit so as to keep the power supplied from the power amplification unit to the load at a set value;
A high-frequency power supply device. A first high-frequency signal and a second high-frequency signal having different frequencies are generated by generating a high-frequency signal having an output frequency commanded by a frequency command and an output amplitude level commanded by an amplitude level command. First and second high frequency generators;
A frequency controller for giving the frequency command to the first and second high-frequency generators so as to keep a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal constant;
A power amplifier for amplifying the first high-frequency signal;
A high frequency detection unit for detecting a traveling wave detection signal including information on traveling wave power from the power amplification unit toward the load and a reflected wave detection signal including information on reflected wave power from the load side toward the power amplification unit;
Multiplying the traveling wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal includes a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A first multiplier for obtaining a signal;
A first filter for extracting a first difference frequency signal having a frequency component of a difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal from the output of the first multiplication unit;
A first difference frequency signal level detection unit for detecting a level of the first difference frequency signal extracted by the first filter;
Multiplication of the reflected wave detection signal obtained by the high-frequency detection unit and the second high-frequency signal includes a frequency component of a difference between the frequency of the first high-frequency signal and the frequency of the second high-frequency signal. A second multiplier for obtaining a signal;
A second filter for extracting a second difference frequency signal having a frequency component of a difference between the frequency of the first high frequency signal and the frequency of the second high frequency signal from the output of the second multiplication unit;
A second difference frequency level detection unit for detecting a level of the second difference frequency signal extracted by the second filter;
A level obtained by subtracting the level detected by the second difference frequency signal level detection unit from the level detected by the first difference frequency signal level detection unit is compared with the first set level, and the calculation result is obtained. A first level control unit that gives the amplitude command to the first high-frequency generator so as to keep the power applied from the power amplifier to the load at a set value;
An output level detector for detecting an output level of the second high frequency generator;
The level detected by the output level detection unit is compared with a second set level, and the second high frequency generation unit is maintained at a set constant value based on the calculation result. A second level control unit for giving an amplitude command to the high frequency generation unit of
A high-frequency power supply device.   5. The high-frequency power supply device according to claim 1, wherein each filter includes an analog filter or a digital filter.   5. The high-frequency power supply device according to claim 1, wherein each filter includes a combination of an analog filter and a digital filter that digitally processes an output of the analog filter to extract the difference frequency signal. .

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