JP6153786B2 - High frequency power supply - Google Patents

Description

  The present invention relates to a high frequency power supply apparatus that supplies high frequency power to a load such as a plasma processing apparatus.

  When processing various objects to be processed, a technique is used in which high-frequency power is radiated to a gas in a process chamber to form plasma. For example, in a semiconductor manufacturing process, high-frequency power is supplied to an electrode disposed in a process chamber, and the high-frequency power is radiated into the chamber, thereby plasmaizing the gas in the chamber and supplying the plasmaized gas to the object to be processed. Thus, the etching process is performed.

  As a high-frequency power supply device that supplies high-frequency power to a plasma load or the like, as shown in Patent Document 1, a DC-DC converter that boosts or lowers a DC voltage obtained by rectifying the output of a commercial power supply, and this A DC-RF converter that converts the DC output of the DC-DC converter to a high-frequency output (RF output), and an output of the DC-DC converter that keeps the high-frequency output that is output from the DC-RF converter at a set value. A device including a high-frequency output control unit for controlling is known.

  In recent years, in a semiconductor manufacturing process, in order to enable fine etching processing, high-frequency power modulated by a modulated wave having a waveform such as a pulse waveform or a stepped waveform is radiated into a process chamber. It has become. When using modulated high-frequency power for plasma processing, it is necessary to manage each instantaneous level (magnitude) of the modulated high-frequency power so that it is accurately maintained at the set value. Along with miniaturization, it is required to perform management more precisely and supply stable high-frequency power to the electrodes in the process chamber.

  As described above, the high-frequency power supply apparatus that obtains the high-frequency power modulated by the modulated wave having a waveform such as a pulse waveform can be configured as shown in FIG. In FIG. 12, 1 is an AC-DC converter that converts an AC input (AC input) obtained from a commercial power source or the like into a DC voltage (DC voltage), and 2 is a DC voltage obtained from the AC-DC converter 1 as desired. DC-DC converter (DC-DC converter) for converting to a DC voltage having a level, 3 a DC-RF converter for converting the output of the DC-DC converter 2 to high frequency power (RF power), 4 for DC- This is a high-frequency output detector that detects at least a traveling wave component of the high-frequency power applied from the RF converter 3 to the load. Reference numeral 5 denotes a high-frequency output setting unit that sets a set value of a level that the modulated high-frequency power should take instantaneously when the high-frequency power modulated by the modulation waveform set by the DC-RF conversion unit is output. This is a high-frequency power control unit that controls the DC-DC conversion unit 2. The high frequency power control unit 6 has a DC-DC conversion unit so that the instantaneous level of the high frequency power detected by the high frequency output detection unit 4 is equal to the set value of each instantaneous level set by the high frequency output setting unit 5. 2 is controlled.

  In FIG. 12, the DC-RF conversion unit 3 can be configured by a circuit that amplifies a high-frequency signal using the DC voltage output from the DC-DC conversion unit 2 as a power source. As a method for controlling the output of the DC-DC converter 2, as shown in Patent Document 2, a control command signal including information on the deviation between the set value of the output and the detected value is converted into a triangular wave or a sawtooth shape. A technique is generally used in which a switch element constituting a DC-DC converter is subjected to on / off control (PWM control) using a PWM control signal obtained by comparison with a carrier signal having a waveform.

As described above, the DC-DC converter and the DC-RF converter that converts the output of the DC-DC converter into high-frequency power are provided, and the level is set by PWM control of the DC-DC converter. In a high-frequency power supply device that obtains a high-frequency power maintained at a value, in order to modulate the high-frequency power with a modulated wave having a predetermined waveform, the set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit 5 And a PWM control signal obtained by comparing a control command signal including information on a deviation between the detected value of each instantaneous level of the modulated high-frequency power detected by the high-frequency output detection unit 4 with a carrier signal. A DC-DC converter is supplied to the converter 2 so that the DC-RF converter 3 outputs modulated high-frequency power whose instantaneous level is equal to the instantaneous level set by the high-frequency output setting unit 5. It is sufficient to control the output parts. In this case, the high frequency power control unit 6 can be configured as shown in FIG. 13, for example.

  The high-frequency output detector 4 shown in FIG. 13 includes, for example, a directional coupler that detects a traveling wave component of a high-frequency voltage from the output of the DC-RF converter 3, and a high-frequency voltage detected by the directional coupler. A detection circuit that extracts envelope waveform information of a traveling wave component and outputs a high-frequency voltage detection signal, and converts the high-frequency voltage detection signal obtained from the detection circuit into a high-frequency power detection signal Vrf that indicates power applied to a load And converting means.

  The high-frequency output setting unit 5 can compare the high-frequency power setting signal Vm that gives a set value of a level that the high-frequency power should take at each moment when the high-frequency power is modulated with a predetermined modulation waveform with the high-frequency power detection signal Vrf. (With a waveform that can be compared with the high-frequency power detection signal Vrf). The high frequency power setting signal Vm is a signal having a waveform similar to that of a modulated wave (pulse in this example), and the level thereof corresponds to the level that the high frequency power should take instantaneously.

Among various elements constituting the high-frequency power control unit 6 shown in FIG. 13, reference numeral 601 denotes a high-frequency signal generation unit that generates a high-frequency signal equal to the output frequency of the DC-RF conversion unit 3 (the output frequency of the high-frequency power supply device). It is. Reference numeral 602 calculates a deviation between the high-frequency power detection signal Vrf output from the high-frequency output detection unit 4 and the high-frequency power setting signal output from the high-frequency output setting unit 5, and a control calculation such as PID calculation and amplification are performed on the deviation. Is included, and information on the deviation between the set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit 5 and the instantaneous level of the high-frequency power detected by the high-frequency output detecting unit 4 is included. An error amplifier 603 ′ for outputting the control command signal Ve, a carrier signal generator 603 for generating a carrier signal Vc having a constant frequency higher than the frequency of the modulation wave (hereinafter referred to as modulation frequency), and 604 for an error amplifier. Is a PWM control signal generator that generates a PWM control signal Vpwm to be supplied to the DC-DC converter 2 by comparing the control command signal Ve obtained from the carrier signal Vc with the carrier signal Vc. .

  The AC-DC converter 1 shown in FIG. 13 can be configured by a circuit that rectifies and smoothes a commercial AC voltage and outputs a DC voltage. The DC-DC converter 2 has, for example, a configuration in which a plurality of legs whose upper and lower arms are configured by switch elements are connected in parallel, and a DC voltage applied from the AC-DC converter 1 by turning on and off the switch elements. Can be configured by a well-known DC-DC converter including a full-bridge inverter circuit that converts AC to AC voltage and a rectifier circuit that rectifies the AC voltage output from the inverter circuit. When the DC-DC converter is constituted by such a DC-DC converter, the switch elements constituting the inverter circuit in the DC-DC converter are on-off controlled (PWM controlled) with a predetermined duty ratio by the PWM control signal. Thus, a pulsed DC voltage whose level is controlled from the DC-DC converter 2 can be output.

  The DC-RF converter 3 includes, for example, an inverter circuit that converts a direct current output obtained from the DC-DC converter 2 into a high-frequency output having a frequency equal to the frequency of the high-frequency signal output from the high-frequency signal generator 601; It can be constituted by a class D amplifier provided with a circuit for removing harmonic components from the high frequency output obtained from the inverter circuit.

  FIG. 14 shows the signal waveform of each part of the high-frequency power control unit 6 shown in FIG. 13 with respect to time t. 14A shows the waveform of the carrier signal Vc by a solid line, the waveform of the control command signal Ve obtained from the error amplifying unit by a broken line, and FIG. 14B shows the waveform of the high-frequency power setting signal Vm. FIG. 14C shows the waveform of the PWM control signal Vpwm. FIGS. 14D and 11E show the waveform of the DC voltage Vdc output by the DC-DC converter 2 and the output of the DC-RF converter 3, respectively. The waveform of the high frequency voltage envelope is shown. Of the waveform of the high-frequency voltage output from the DC-RF conversion unit 3 [FIG. 14E], the portion indicated by the light ink color inside the envelope is the waveform of the high-frequency signal output from the high-frequency signal generation unit 601. Corresponding high frequency AC waveform.

  The carrier signal generation unit 603 ′ generates a carrier signal Vc having a sawtooth waveform having a frequency sufficiently higher than the modulation frequency and lower than the output frequency of the high frequency power supply device, and the PWM control signal generation unit 604 performs control. The command signal Ve and the carrier signal Vc are compared to indicate a high level during the period when the level of the control command signal Ve exceeds the level of the carrier signal Vc, and the level of the control command signal Ve becomes equal to or lower than the level of the carrier signal Vc. The PWM control signal Vpwm (FIG. 14C) having a pulse waveform indicating a low level during the period is supplied to the switch element of the DC-DC converter 2. The DC-DC converter 2 has a waveform similar to that of a modulated wave (pulse in this example), and has a level necessary for making the value of the high-frequency power output from the DC-RF converter 3 equal to the set value. The direct-current voltage Vdc [FIG. 14 (D)] is applied to the DC-RF converter 3. In this case, the frequency of the carrier signal Vc (the frequency of the PWM control signal) becomes a switching frequency when the DC-DC conversion unit 2 is subjected to PWM control.

  The DC-RF converter 3 converts the DC output Vdc of the pulse waveform given from the DC-DC converter 2 into high-frequency power having a frequency equal to the frequency of the high-frequency signal output from the high-frequency signal generator 601. A high frequency power modulated by a pulse (modulated wave) and controlled so that the level becomes equal to the set value set by the high frequency power setting signal Vm is applied to a load (not shown).

JP 2012-50296 A JP 2006-246598 A

  In the high-frequency power supply device having the above-described configuration, as shown in FIG. 14C, due to the synchronization shift between the modulated wave and the carrier signal, the PWM control signal Vpwm increases with time. The state in which the phase is slightly shifted is repeated periodically, whereby the waveform of the envelope of the high frequency voltage output from the DC-RF converter 3 fluctuates at a frequency lower than the modulation frequency, and in particular, the high frequency voltage. In some cases, the level of the high-frequency power applied to the load fluctuates at a frequency lower than the modulation frequency near the rise of the envelope waveform. This variation is referred to as low frequency variation of high frequency power. This low frequency fluctuation is particularly noticeable when the modulated wave has a waveform showing a step-like level change such as a pulse waveform or a stepped waveform.

Here, assuming that the PWM operation cycle is Tpwm [see FIG. 14A] and the modulation wave cycle is Tp, the deviation Tdiff between the PWM operation cycle and the modulation wave cycle is given by the following equation (1).
Tdiff = | n · Tpwm−Tp | (1)
Here, n is the number (integer) of PWM operation cycles giving the minimum value of | n · Tpwm−Tp |, and n = 6 in the example shown in FIG. When the deviation time due to repetition (stacking) of deviations is the same as the PWM operation period Tpwm, the same operation is repeated again. Assuming that the number of repetitions until the shift time reaches the same time as the PWM operation cycle Tpwm is Nrep, Nrep is given by the following equation (2).
Nrep = Tpwm / Tdiff
= Tpwm / | n · Tpwm-Tp | (2)
Since the time corresponding to the number of repetitions is a period of fluctuation that occurs at a frequency lower than the frequency of the modulation wave, the period Tm of the fluctuation is given by the following equation (3).
Tm = Nrep.Tp = (Tpwm.Tp) / | n.Tpwm-Tp | (3)
Therefore, the frequency fm of the low frequency fluctuation caused by the synchronization shift between the carrier signal and the modulated wave is given by the following equation (4).
fm = 1 / Tm = | n.Tpwm-Tp | / (Tpwm.Tp) (4)

  For example, when the frequency of a pulse that is a modulated wave is 8 kHz (period 125 μs) and the PWM frequency (carrier frequency) is 250 kHz (PWM operation period: 4 μs), the pulses that constitute the PWM control signal within one period of the pulse waveform ( PWM pulse) appears 31 times, and n · Tpwm = 124 μs. Accordingly, a shift of a period of Tdiff = 125 μs−124 μs = 1 μs occurs. In this case, the shift time becomes the same as the PWM operation cycle of 4 μs after 4 μs / 1 μs = 4 cycles, so that the low frequency of the high frequency power caused by the synchronization shift between the carrier signal and the modulated wave is low. The fluctuation period is 125 μs × 4 = 500 μs.

  As described above, when the high-frequency power fluctuates at a low frequency, a phenomenon occurs in which the rising waveforms of the modulated waves appearing in the waveform of the envelope of the high-frequency voltage output from the DC-RF converter do not become the same. The high-frequency power level fluctuates near the rise. When high-frequency power waveforms need to be precisely controlled, such as when high-frequency power is used to generate plasma used for semiconductor etching, the high-frequency power supplied to the load is low. It is necessary to avoid as much as possible that the frequency fluctuates.

  An object of the present invention is to provide a carrier signal used when generating a PWM control signal to be supplied to a DC-DC converter when high-frequency power to be applied to a load is modulated by a modulated wave having a waveform such as a pulse waveform or a stepped waveform. Provided is a high-frequency power supply device that can always be synchronized with a modulated wave to prevent a phenomenon in which the level of high-frequency power fluctuates at a frequency lower than the modulation frequency. There is to do.

The present invention relates to a DC-DC converter capable of output level PWM control, a DC-RF converter that converts the output of the DC-DC converter into a high-frequency output, and a waveform set by the DC-RF converter. A high-frequency output setting unit that sets a set value of a level that the modulated high-frequency power should take instantaneously when outputting the high-frequency power modulated by the modulated wave, and the high-frequency power output from the DC-RF converter A high-frequency output detection unit that detects each instantaneous level, a set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit, and a detection value of each instantaneous level of the high-frequency power detected by the high-frequency output detection unit The PWM control signal obtained by comparing the control command signal including the deviation information with the carrier signal is supplied to the DC-DC converter, and each instantaneous level is set by the high frequency output setting unit. It targets high-frequency power supply device and a high frequency power control unit for controlling the output of the DC-DC converter unit in order to output a high frequency power modulated equal to the level of DC-RF converter unit.

  In the present invention, in order to achieve the above object, the frequency of the carrier signal is set to an integral multiple of the frequency of the modulated wave.

  As described above, if the frequency of the carrier signal used when obtaining the PWM control signal is set to an integer multiple of the frequency of the modulated wave, the carrier signal and the modulated wave can be synchronized, It is possible to prevent the level of the high-frequency power output from the DC-RF converter from fluctuating at a frequency lower than the frequency of the modulation wave.

In a preferred aspect of the present invention, the high-frequency output setting unit has a frequency equal to the frequency of the modulated wave, and the high-frequency power setting signal in which each instantaneous level corresponds to the level that the modulated high-frequency power should take at each instant Configured to generate. In this case, the high frequency power control unit receives the high frequency power setting signal and the output of the high frequency output detection unit as inputs, and is detected by the set value of each instantaneous level of the high frequency power set by the high frequency output setting unit and the high frequency output detection unit. An error amplifying unit that generates a control command signal including deviation information from the detected value of each instantaneous level of the high-frequency power, and a carrier frequency that calculates the frequency of the carrier signal by multiplying the frequency of the high-frequency power setting signal by an integer A calculation unit, a carrier signal generation unit that generates a carrier signal having a frequency calculated by the carrier frequency calculation unit, and a PWM control signal generation unit that outputs a PWM control signal by comparing the carrier signal and the control command signal. It is set as the structure provided.

  When configured as described above, the frequency of the carrier signal used when obtaining the PWM control signal to be supplied to the DC-DC converter is always kept at an integer multiple of the frequency of the modulation wave, and is synchronized with the carrier signal and the modulation wave. Therefore, it is possible to prevent the level of the high frequency power output from the DC-RF converter from fluctuating at a frequency lower than the frequency of the modulation wave. When the frequency of the modulation wave that modulates the high frequency power is changed, the switching frequency of the PWM control can be immediately adjusted to an integer multiple of the frequency of the modulation wave after the change. It is possible to respond to a request to change the frequency appropriately.

In another preferred aspect of the present invention, the high frequency power control unit has a frequency equal to the frequency of the modulated wave, and each instantaneous level corresponds to each instantaneous level of the high frequency power set by the high frequency output setting unit. The high-frequency power setting signal generating unit that generates the high- frequency power setting signal, and the high-frequency power setting signal and the output of the high-frequency output detection unit are used as inputs to set the instantaneous level of the high-frequency power set by the high-frequency output setting unit. An error amplifying unit for generating a control command signal including deviation information between the value and the detected value of each instantaneous level of the high-frequency power detected by the high-frequency output detecting unit, and the frequency of the high-frequency power setting signal that is the frequency of the modulation wave Is multiplied by an integer to calculate the carrier signal frequency, and the carrier frequency calculation unit generates a carrier signal having the frequency calculated by the carrier frequency calculation unit. A signal generating section, and a PWM control signal generator for outputting a PWM control signal by comparing the carrier signal and the control command signal.

  The level fluctuation of the high-frequency power that occurs near the rising edge of the modulation wave waveform due to the low-frequency fluctuation of the high-frequency power appears particularly conspicuously when the waveform of the modulation wave shows a step-like change. Therefore, the present invention is particularly useful when the waveform of the modulation wave set by the high frequency output setting unit is a pulse waveform or a stepped waveform.

  According to the present invention, a DC-DC conversion unit, a DC-RF conversion unit that converts a DC voltage obtained from the DC-DC conversion unit into high-frequency power, and a level of the modulated high-frequency power held at a set value. In a high frequency power supply apparatus including a high frequency power control unit that PWM-controls the DC-DC conversion unit so that the DC-RF conversion unit outputs the PWM control signal in a state, a control command is given when obtaining a PWM control signal to be given to the DC-DC conversion unit Since the frequency of the carrier signal to be compared with the signal is set to an integral multiple of the frequency of the modulated wave, the carrier signal and the modulated wave are maintained in a synchronized state, and the DC-RF converter Can be prevented from fluctuating at a frequency lower than the frequency of the modulated wave.

  Further, according to the invention described in claim 2 or 3, since the frequency of the carrier signal can be immediately adjusted to an integral multiple of the frequency of the modulated wave after the change even when the frequency of the modulated wave is changed, It is possible to easily adapt to the request to change the frequency of the modulated wave.

1 is a block diagram schematically showing a configuration of an embodiment of the present invention. It is the block diagram which showed schematically the structure of other embodiment of this invention. It is the circuit diagram which showed the structural example of the DC-DC conversion part which can be used by embodiment of this invention. (A) thru | or (D) showed typically the waveform of the drive signal given to each switch element of the inverter circuit which comprises the conversion part in the control method of the DC-DC conversion part shown in FIG. It is a waveform diagram. (A) to (E) are the other control methods of the DC-DC co-conversion unit shown in FIG. 3, and the waveforms of drive signals given to the respective switch elements of the inverter circuit constituting the conversion unit, and the inverter circuit It is the wave form diagram which showed typically the waveform of the voltage output from. It is the circuit diagram which showed the structural example of the DC-RF conversion part which can be used by embodiment of this invention. It is the circuit diagram which showed the other structural example of the DC-RF conversion part which can be used by embodiment of this invention. It is the circuit diagram which showed the further another structural example of the DC-RF conversion part which can be used by embodiment of this invention. It is the circuit diagram which showed the further another structural example of the DC-RF conversion part which can be used by embodiment of this invention. (A) thru | or (E) are the waveform diagrams which showed the signal waveform of each part of embodiment shown in FIG. (A) thru | or (E) are the wave form diagrams which showed the other signal waveform of each part of embodiment shown in FIG. It is the block diagram which showed the general structure of the high frequency power supply device which this invention makes object. It is the block diagram which showed the structure of the high frequency electric power control part of the conventional high frequency power supply device. (A) thru | or (E) are the waveform diagrams which showed the signal waveform of each part of the conventional high frequency power supply device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, it is assumed that the waveform of the modulation wave that modulates the high-frequency power is a pulse waveform. FIG. 1 shows a configuration of an embodiment of a high-frequency power supply device according to the present invention. In FIG. 1, reference numeral 1 denotes an AC-DC converter that converts an AC voltage into a DC voltage, and 2 denotes an AC-DC converter 1. A DC-DC converter 3 converts the obtained DC voltage into a DC voltage having a pulse waveform (modulated wave waveform) having a desired level. DC-RF 3 converts the output of the DC-DC converter 2 into high-frequency power. The conversion unit 4 is a high-frequency output detection unit that detects at least a traveling wave component of the high-frequency power applied to the load from the DC-RF conversion unit 3, and 5 is modulated with a modulated wave having a waveform set from the DC-RF conversion unit 3. high-frequency output setting unit which high-frequency power which is modulated when to output a high frequency power that is to set the level of the setting value to be taken each instant, 6 out high frequency level of the high-frequency power detected by the high-frequency output detector 4 Is a high-frequency power control unit for controlling the DC-DC converter unit 2 so as to equal the set value set by the setting unit 5.

  The AC-DC converter 1 includes a rectifier circuit that rectifies commercial AC voltage and a smoothing circuit that smoothes the output of the rectifier circuit.

  As the DC-DC converter 2, for example, two legs (upper and lower arms connected in series) in which upper and lower arms are constituted by semiconductor switching elements such as MOSFETs capable of high-speed switching, are used. A full-bridge type inverter circuit configured by connecting in parallel or a half-bridge type inverter circuit having a single leg, a transformer for transforming the output of the inverter circuit, and an inverter circuit obtained on the secondary side of the transformer A circuit including a rectifier circuit that rectifies the PWM output and an LC smoothing circuit that reduces the ripple of the output of the rectifier circuit can be used.

  FIG. 3 shows a configuration example of a DC-DC converter using a full bridge type inverter circuit. In this example, an inverter circuit is configured by connecting a leg composed of a series circuit of MOSFETs Q1 and Q2 and a leg composed of a series circuit of MOSFETs Q3 and Q4 in parallel, and the output of the inverter circuit is input to a transformer T. ing. The output of the transformer T is input to a full-wave rectifier circuit composed of a full bridge circuit of diodes D1 to D4, and the output of the full-wave rectifier circuit is input to a smoothing circuit composed of a coil L1 and a capacitor C1.

  The DC-DC converter 2 shown in FIG. 3 supplies, for example, drive signals Vg1 to Vg4 having waveforms as shown in FIGS. 4A to 4D to the gates of the MOSFETs Q1 to Q4. Each MOSFET is driven by turning on each MOSFET while each drive signal is at a high level. In the example shown in FIG. 4, the output voltage of the DC-DC converter 2 is PWM controlled by changing the on-duty ratio of each MOSFET by changing the on-period Ton of each MOSFET.

  Further, as shown in FIGS. 5A to 5D, the duty of the drive signals Vg1 to Vg4 supplied to the gates of the MOSFETs Q1 to Q4 is set to 50% (constant), and the levels of the drive signals Vg1 and Vg4 are set. In some cases, the output voltage of the DC-DC converter 2 is PWM controlled by phase shift PWM control for controlling the phase difference θ and the phase difference θ between the drive signal Vg2 and the drive signal Vg3. FIG. 5E shows the waveform of the voltage V1 input to the transformer T from the inverter circuit.

  The DC-RF converter 3 that converts the output of the DC-DC converter 2 into high-frequency power can be configured by a switching amplifier such as a class D amplifier or a class E amplifier. As shown in FIG. 6, the class D amplifier includes a half-bridge inverter circuit composed of MOSFETs Q11 and Q12, a filter circuit composed of a capacitor C11 and an inductor L11, and a transformer T11. As shown in FIG. 7, it is also possible to use a circuit composed of a full-bridge inverter circuit composed of MOSFETs Q11 to Q14, a filter circuit composed of a capacitor C11 and an inductor L11, and a transformer T11. A push-pull class D amplifier can also be used.

  As the class E amplifier, for example, as shown in FIG. 8, a known single-configuration amplifier circuit constituted by a MOSFET Q31, a choke coil L31, capacitors C31 and C32, an inductor L32, and a transformer T3 is used. As shown in FIG. 9, there is provided a push-pull amplifier circuit constituted by MOSFETs Q41 and Q42, choke coils L41 and L42, capacitors C41 to C43, an inductor L43, and a transformer T4. Etc. can be used.

  In the case of configuring a high-output high-frequency power supply device, a configuration in which a plurality of amplifier circuits are provided in the DC-RF converter 3 and outputs of the plurality of amplifier circuits are combined by a power combiner and supplied to a load. Sometimes it takes.

  The high-frequency output detection unit 4 shown in FIG. 1 detects at least a traveling wave component of the high-frequency output output from the DC-RF conversion unit 3 and supplied to the load. For example, the DC-RF conversion unit 3 Directional coupler for detecting the traveling wave component of the high frequency voltage from the output of the detector, the detection circuit for extracting the waveform information of the envelope of the traveling wave component of the high frequency voltage detected by the directional coupler, and the detection circuit And a conversion means for converting the high-frequency voltage detection signal obtained from the above into a signal indicating the power applied to the load. When the high-frequency power is modulated by a pulse, the high-frequency output detection unit 4 outputs a high-frequency power detection signal Vrf having a pulse waveform indicating the level of the high-frequency power modulated by the pulse. When the reflected wave power returning from the load side cannot be ignored, it is necessary to control the output of the high-frequency power supply device in consideration of the reflected wave power. It is comprised so that both of these may be detected.

  The high-frequency output setting unit 5 is a part for setting a waveform of a pulse that modulates the high-frequency power output from the DC-RF conversion unit 3 and a set value of a level that the high-frequency power modulated by the pulse should take instantaneously. An interface unit for inputting information to be set by a keyboard, a digital switch, and the like, and a frequency equal to the frequency of the modulated wave, and each instantaneous level corresponds to a level at which the modulated high-frequency power should be instantaneously Signal generating means for generating a high-frequency power setting signal. In the present embodiment, the high-frequency output setting unit 5 also serves as a high-frequency power setting signal generation unit.

The high frequency power control unit 6 performs control calculation such as PID calculation and amplification on the deviation between the high frequency power setting signal Vm given from the high frequency output setting unit 5 and the high frequency power detection signal Vrf given from the high frequency output detection unit 4. The control command signal including information on the deviation between the set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit 5 and the detected value of each instantaneous level of the high-frequency power detected by the high-frequency output detecting unit 4 An error amplifying unit 602 that generates Ve, a carrier frequency calculating unit 605 that calculates a carrier frequency for the frequency of the modulated wave set by the high frequency output setting unit 5, and a carrier frequency calculated by the carrier frequency calculating unit 605 The carrier signal generator 603 for generating the carrier signal Vc having the control signal is compared with the carrier signal Vc and applied to the DC-DC converter 2. And a PWM control signal generator 604 for generating a PWM control signal Vpwm.

  In the present embodiment, a signal having the same waveform (pulse waveform) as the high frequency power setting signal Vm is given from the high frequency output setting unit 5 to the carrier frequency calculation unit 605. In this case, the carrier frequency calculation unit 605 calculates the carrier frequency (the frequency of the carrier signal) by detecting the frequency of the signal given from the high frequency output setting unit 5 and multiplying the detected frequency by an integer.

  In the embodiment shown in FIG. 1, all the components of the high frequency power control unit 6 are configured in an FPGA (Field Programmable Gate Array), and the high frequency power setting signal Vm output from the high frequency output setting unit 5 is transmitted to the FPGA. The

  The configuration of the high frequency power control unit 6 shown in FIG. 1 includes a carrier frequency calculation unit 605 that calculates the frequency of the carrier signal by multiplying the frequency of the high frequency power setting signal Vm, which is the frequency of the modulated wave, by an integer. Except for the point and the point that the carrier signal generation unit 603 is configured to generate a carrier signal having the frequency calculated by the carrier frequency calculation unit 605, the high frequency used in the high frequency power supply device shown in FIG. The configuration is the same as that of the power control unit.

The high frequency power detection signal Vrf and the high frequency power setting signal Vm are supplied to the error amplification unit 602. The error amplifying unit 602 performs control calculation such as PID calculation and amplification on the deviation between the high frequency power setting signal Vm and the high frequency power detection signal Vrf, and each instantaneous level of the high frequency power set by the high frequency output setting unit 5. Control command signal Ve [see FIG. 10 (A)] including deviation information so that the deviation between the set value and the detected value of the instantaneous level of the high-frequency power detected by the high-frequency output detector 4 is zero. Occur. The level of the control command signal Ve changes according to the deviation between the set value of the high frequency power set by the high frequency output setting unit 5 and the level of the high frequency power detected by the high frequency output detection unit 4. Further, when the set value of the high frequency power set by the high frequency output setting unit 5 is increased, the level of the control command signal Ve increases. When the set value of the high frequency power set by the high frequency output setting unit 5 is decreased, the level of the control command signal Ve. Becomes smaller.

The carrier frequency calculation unit 605 calculates the carrier frequency by detecting the frequency (frequency of the modulated wave) of the high frequency power setting signal output from the high frequency output setting unit 5 and multiplying the detected frequency by an integer. The carrier frequency is calculated to be n (n is an integer) times the frequency of the modulated wave, and the following relationship is established among the frequency of the modulated wave, the carrier frequency, and the output frequency of the high frequency power supply.
Modulated Wave Frequency << Carrier Frequency << Output Frequency of High Frequency Power Supply Device The carrier signal Vc is generally a signal having a sawtooth waveform or a triangular waveform as shown in FIG.

  The PWM control signal generation unit 604 compares the control command signal Ve obtained from the error amplification unit 602 with the carrier signal Vc obtained from the carrier signal generation unit 603, and as shown in FIG. A PWM control signal Vpwm indicating a high level during the period when the level of the signal Ve exceeds the level of the carrier signal Vc and a low level during a period when the level of the control command signal Ve is equal to or lower than the level of the carrier signal Vc is output.

  The PWM control signal output from the PWM control signal generator 604 is given to the control terminal of the switch element of the DC-DC converter 2. The DC-DC converter 2 has a level necessary for controlling the level of the high-frequency power output from the DC-RF converter 3 to a set value, and has a waveform of a modulated wave (in this example, a pulse waveform). The DC voltage Vdc [(FIG. 10D)] controlled as described above is applied to the DC-RF converter 3. Accordingly, the DC-RF converter 3 has the envelope of the voltage waveform shown in FIG. In this way, high-frequency power having a pulse-like waveform is output.

  In this embodiment, a carrier frequency calculation unit 605 that calculates the frequency of a carrier signal as a frequency that is an integral multiple of the frequency of the modulated wave (pulse) set by the high-frequency output setting unit is provided, and the carrier having the calculated carrier frequency Since the signal is generated, the modulation wave and the carrier signal can always be synchronized, and, as is apparent from FIG. 10, the phase shift of the PWM control signal occurs in each period of the modulation wave. It is possible to prevent the phenomenon that the high-frequency power output from the DC-RF converter 3 fluctuates at a frequency lower than the frequency of the modulation wave.

  In this embodiment, the carrier frequency calculation unit 605 and the carrier signal generation unit 603 use the PWM frequency of the DC-DC conversion unit 2 to set the switching frequency to the frequency of the modulated wave set by the high frequency output setting unit 5. A switching frequency control means for maintaining an integral multiple is configured.

  In the above description, the high-frequency power control unit 6 is configured by one FPGA. However, the configuration of the high-frequency power control unit 6 is arbitrary and is not limited to the above embodiment. For example, a part of the constituent elements of the high-frequency power control unit 6 may be configured by an FPGA, and the other part may be configured by an analog IC having an external clock input, a microcomputer, a DSP (Digital Signal Processor), or the like.

  For example, in FIG. 1, the high frequency signal generation unit 601 and the carrier frequency calculation unit 605 are configured by an FPGA, and the error amplification unit 602, the carrier signal generation unit 603, and the PWM control signal generation unit 604 are configured by an analog IC. You can also

  In the above embodiment, the high-frequency output setting unit 5 is configured to output the high-frequency power setting signal Vm. However, the high-frequency output setting unit 5 includes the level information of the high-frequency power output from the DC-RF conversion unit 3 and 2 is configured by an interface (for example, a keyboard) having a function of outputting data (waveform and frequency) for specifying a modulated wave for modulating high-frequency power as digital information, and as shown in FIG. 2, a high-frequency output setting unit A high frequency power setting signal generating unit 600 that outputs a high frequency power setting signal based on the digital information given from 5 may be provided in the high frequency power control unit 6.

  In the above embodiment, the modulation wave that modulates the high-frequency power is a rectangular pulse, but the present invention can also be applied to the case where the high-frequency power is modulated by a modulation wave having another arbitrary waveform. For example, as shown in FIG. 11, the present invention can also be applied to the case where high-frequency power is modulated by a modulated wave having a stepped waveform that changes stepwise. FIG. 11A shows the carrier signal Vc and the control command signal Ve. 1B shows the high frequency power setting signal Vm1 that the high frequency output setting unit 5 shown in FIG. 1 gives to the error amplification unit 602, and FIG. 1C shows the carrier frequency calculation shown in FIG. The pulse signal Vm2 given from the high frequency output setting unit 5 to the carrier frequency calculation unit 605 in order to give information on the repetition period of the modulated wave to the unit 605 is shown. FIG. 14D shows the PWM control signal Vpwm, and FIGS. 14E and 11F show the waveform of the DC voltage Vdc output from the DC-DC converter 2 and the high frequency output from the DC-RF converter 3, respectively. The voltage waveform is shown.

  In each of the above embodiments, each element constituting the high-frequency power control unit 6 may be configured by hardware, or may be configured by causing a microprocessor to execute a predetermined program.

DESCRIPTION OF SYMBOLS 1 AC-DC conversion part 2 DC-DC conversion part 3 DC-RF conversion part 4 High frequency output detection part 5 High frequency output setting part 6 High frequency power control part 600 High frequency power setting signal generation part 601 High frequency signal generation part 602 Error amplification part 603 Carrier signal generator 604 PWM control signal generator 605 Carrier frequency calculator

Claims (5)

A DC-DC converter capable of PWM control of the output level, a DC-RF converter that converts the output of the DC-DC converter into a high-frequency output, and a modulation having a waveform set by the DC-RF converter A high-frequency output setting unit that sets a setting value of a level that the modulated high-frequency power should take instantaneously when outputting the high-frequency power modulated by the wave, and each of the high-frequency power output from the DC-RF conversion unit A high-frequency output detection unit that detects an instantaneous level, a set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit, and a detection of each instantaneous level of the high-frequency power detected by the high-frequency output detection unit A PWM control signal obtained by comparing a control command signal including information of deviation from a value with a carrier signal is applied to the DC-DC converter, and each instantaneous level is set to the high-frequency output setting unit. A high-frequency power supply apparatus comprising: a high-frequency power control unit that controls an output of the DC-DC conversion unit to output a modulated high-frequency power equal to each set instantaneous level from the DC-RF conversion unit. ,
The frequency of the carrier signal is set to an integral multiple of the frequency of the modulated wave. The high-frequency output setting unit generates a high-frequency power setting signal having a frequency equal to the frequency of the modulated wave, and the modulated high-frequency power corresponds to a level to be taken at each instant. Composed of
The high frequency power control unit includes:
Using the high-frequency power setting signal and the output of the high-frequency output detection unit as inputs, the set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit and the high-frequency power detected by the high-frequency output detection unit An error amplifying unit for generating a control command signal including information on deviation from the detected value of each instantaneous level;
A carrier frequency calculation unit that calculates the frequency of the carrier signal by multiplying the frequency of the high-frequency power setting signal by an integer,
A carrier signal generator for generating a carrier signal having a frequency calculated by the carrier frequency calculator;
A PWM control signal generator that compares the carrier signal with the control command signal and outputs the PWM control signal;
The high frequency power supply device according to claim 1, comprising: The high frequency power control unit includes:
High-frequency power setting signal generation for generating a high-frequency power setting signal having a frequency equal to the frequency of the modulation wave and corresponding to each instantaneous level of the high-frequency power set by the high-frequency output setting unit And
Using the high-frequency power setting signal and the output of the high-frequency output detection unit as inputs, the set value of each instantaneous level of the high-frequency power set by the high-frequency output setting unit and the high-frequency power detected by the high-frequency output detection unit An error amplifying unit for generating a control command signal including information on deviation from the detected value of each instantaneous level;
A carrier frequency calculation unit that calculates the frequency of the carrier signal by multiplying the frequency of the high-frequency power setting signal that is the frequency of the modulated wave by an integer;
A carrier signal generator for generating a carrier signal having a frequency calculated by the carrier frequency calculator;
The high frequency power supply device according to claim 1, further comprising: a PWM control signal generation unit that compares the carrier signal with the control command signal and outputs the PWM control signal.   The high-frequency power supply device according to claim 1, wherein the waveform of the modulation wave set by the high-frequency output setting unit is a pulse waveform.   The high frequency power supply device according to claim 1, wherein the waveform of the modulation wave set by the high frequency output setting unit is a stepped waveform.

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