Abstract: In a configuration of an isolation circuit using a transformer of a high-frequency-isolation gate driver circuit in the frequency band from 1 to 100 MHz, a period for resetting the exciting current is eliminated, generation of self-resonance phenomenon after resetting is cancelled to reduce generation of noise current, and malfunctions of the switching element due to noise is prevented. In driving plural gate circuits by RF signals, exciting current is allowed to pass through a primary coil of a gate driver transformer alternately in both directions continuously all the time, in a configuration for isolating drive input signals by the gate driver transformer. Accordingly, the reset period that is required when the exciting current flows only in one way becomes unnecessary, and thus generation of self-resonance phenomenon after resetting is canceled. Then, generation of noise current caused by the self-resonance phenomenon is reduced.

Abstract: In a configuration of an isolation circuit using a transformer of a high-frequency-isolation gate driver circuit in the frequency band from 1 to 100 MHz, a period for resetting the exciting current is eliminated, generation of self-resonance phenomenon after resetting is cancelled to reduce generation of noise current, and malfunctions of the switching element due to noise is prevented. In driving plural gate circuits by RF signals, exciting current is allowed to pass through a primary coil of a gate driver transformer alternately in both directions continuously all the time, in a configuration for isolating drive input signals by the gate driver transformer. Accordingly, the reset period that is required when the exciting current flows only in one way becomes unnecessary, and thus generation of self-resonance phenomenon after resetting is canceled. Then, generation of noise current caused by the self-resonance phenomenon is reduced.

Abstract: In an inverter circuit, more particularly in a single-phase inverter, soft switching is performed with a simple configuration to prevent switching loss of a switching element. A resonance circuit is configured by a resonant capacitor provided on the power supply side of a bridge circuit constituting a single phase inverter, a resonant inductor provided on the output side of the bridge circuit, and the bridge circuit. A resonance current passing through the resonance circuit allows zero voltage switching (ZVS) and zero current switching (ZCS) to be implemented at the rising time of main switching elements constituting the bridge circuit, and the zero voltage switching is implemented by means of zero voltage of the resonant capacitor at the falling time of the main switching elements constituting the bridge circuit.

Abstract: An excessive voltage rise of load voltage, caused by an impedance mismatching on a transmission path, is prevented, and high-frequency power is regenerated. A parallel impedance is connected to the transmission path during the voltage rise, thereby regenerating voltage caused by a standing wave and preventing excessive load voltage, together with enhancing energy usage efficiency. Establishing the parallel impedance for the load impedance, on the transmission path between the high-frequency amplifier circuit of the high-frequency power supply device and the high-frequency load, reduces impedance at the connecting position to prevent generation of excessive voltage on the transmission path, and high-frequency power is regenerated from the transmission path by the parallel impedance.

Abstract: In detecting the unignited state of plasma based on a reflected wave, false detection during a normal plasma ignition time is prevented so as to detect the unignited state during plasma abnormality. When a pulse output is supplied to a plasma load by pulse driving from an RF power source, the unignited state of plasma abnormality is detected on the basis of the continuous state of the reflected wave, whereby a total reflected wave generated in the unignited state during plasma abnormality is detected in distinction from the reflected wave generated in the normal ignited state. With this configuration, in detecting the unignited state by comparing a peak value of the reflected wave with a threshold, it is possible to prevent that a reflected wave generated in the normal ignited state is erroneously detected as the total reflected wave that is generated in the abnormal unignited state.

Abstract: In a voltage-type DC power supply provided with an inverter, current supply from the inverter to the load side is suppressed when arc is generated. DC output from the voltage-type DC power supply is suspended and resumed: upon suspending the DC output, the chopper is separated from the inverter, thereby suppressing excessive current to the load when arc is generated, allowing the arc to be extinguished at high speed, and holding the current passing through the chopper in the form of circulating current. Upon restarting the inverter, the circulating current being held is supplied to the load, thereby reducing a delay of supply of DC power to the load at the time of resuming the DC output from the voltage-type DC power supply.

Abstract: In a class-D amplifier, oscillation phenomenon is suppressed in a high RF range and surge voltage is reduced. An oscillation absorption circuit is connected on the power supply side of the class-D amplifier circuit, and the class-D amplifier circuit and thus connected oscillation absorption circuit equivalently configure an oscillation circuit. Resistance provided in the oscillation absorption circuit is assumed as damping resistance of the oscillation circuit, thereby suppressing the oscillation phenomenon and reducing the surge voltage. The oscillation absorption circuit is made up of the RL parallel circuit of resistance and inductance. The oscillation absorption circuit and the class-D amplifier circuit constitute the oscillation circuit, and the resistance of the oscillation absorption circuit constitutes the damping resistance of the oscillation circuit in the high RF range.

Abstract: In an inverter circuit, more particularly in a single-phase inverter, soft switching is performed with a simple configuration to prevent switching loss of a switching element. A resonance circuit is configured by a resonant capacitor provided on the power supply side of a bridge circuit constituting a single phase inverter, a resonant inductor provided on the output side of the bridge circuit, and the bridge circuit. A resonance current passing through the resonance circuit allows zero voltage switching (ZVS) and zero current switching (ZCS) to be implemented at the rising time of main switching elements constituting the bridge circuit, and the zero voltage switching is implemented by means of zero voltage of the resonant capacitor at the falling time of the main switching elements constituting the bridge circuit.

Abstract: In detecting the unignited state of plasma based on a reflected wave, false detection during a normal plasma ignition time is prevented so as to detect the unignited state during plasma abnormality. When a pulse output is supplied to a plasma load by pulse driving from an RF power source, the unignited state of plasma abnormality is detected on the basis of the continuous state of the reflected wave, whereby a total reflected wave generated in the unignited state during plasma abnormality is detected in distinction from the reflected wave generated in the normal ignited state. With this configuration, in detecting the unignited state by comparing a peak value of the reflected wave with a threshold, it is possible to prevent that a reflected wave generated in the normal ignited state is erroneously detected as the total reflected wave that is generated in the abnormal unignited state.

Abstract: A high-frequency power supply device is provided with a plasma ignition step that supplies pulse power to ignite plasma, and drive power supply step to supply drive power for maintaining the plasma being generated. In the plasma ignition step, an ignition pulse being applied in an ignition pulse output operation is configured as including a main pulse that induces ignition, and a prepulse with lower power than the power of the main pulse and being applied at a stage prior to the main pulse. Since the ignition pulse is configured as including the main pulse and the prepulse, this enables protection of a high-frequency power source against reflected wave power, as well as reliably igniting the plasma.

Abstract: A DC power source to supply DC power to a plasma generator is configured as a simple and small-sized device that forms high voltage for generating a plasma discharge. A step of passing a short-circuit current for extremely short time through the voltage source step-down chopper provided in the DC power source and accumulating energy in a reactor is performed repeatedly more than once, so as to discharge the energy accumulated in the reactor to the output capacitance and raise the output voltage sequentially, thereby boosting the voltage up to the ignition set voltage. The short-circuit current is formed by a switching element of a boosting circuit provided in the DC power source. Boosting the voltage at the output terminal by accumulating and discharging the short-circuit current is repeated to raise the voltage at the output terminal of the DC power source up to the ignition set voltage.

Abstract: A DC power source to supply DC power to a plasma generator is configured as a simple and small-sized device that forms high voltage for generating a plasma discharge. A step of passing a short-circuit current for extremely short time through the voltage source step-down chopper provided in the DC power source and accumulating energy in a reactor is performed repeatedly more than once, so as to discharge the energy accumulated in the reactor to the output capacitance and raise the output voltage sequentially, thereby boosting the voltage up to the ignition set voltage. The short-circuit current is formed by a switching element of a boosting circuit provided in the DC power source. Boosting the voltage at the output terminal by accumulating and discharging the short-circuit current is repeated to raise the voltage at the output terminal of the DC power source up to the ignition set voltage.

Abstract: A high-frequency power supply device is provided with a plasma ignition step that supplies pulse power to ignite plasma, and drive power supply step to supply drive power for maintaining the plasma being generated. In the plasma ignition step, an ignition pulse being applied in an ignition pulse output operation is configured as including a main pulse that induces ignition, and a prepulse with lower power than the power of the main pulse and being applied at a stage prior to the main pulse. Since the ignition pulse is configured as including the main pulse and the prepulse, this enables protection of a high-frequency power source against reflected wave power, as well as reliably igniting the plasma.

Abstract: In a voltage-type DC power supply provided with an inverter, current supply from the inverter to the load side is suppressed when arc is generated. DC output from the voltage-type DC power supply is suspended and resumed: upon suspending the DC output, the chopper is separated from the inverter, thereby suppressing excessive current to the load when arc is generated, allowing the arc to be extinguished at high speed, and holding the current passing through the chopper in the form of circulating current. Upon restarting the inverter, the circulating current being held is supplied to the load, thereby reducing a delay of supply of DC power to the load at the time of resuming the DC output from the voltage-type DC power supply.

Abstract: In a class-D amplifier, oscillation phenomenon is suppressed in a high RF range and surge voltage is reduced. An oscillation absorption circuit is connected on the power supply side of the class-D amplifier circuit, and the class-D amplifier circuit and thus connected oscillation absorption circuit equivalently configure an oscillation circuit. Resistance provided in the oscillation absorption circuit is assumed as damping resistance of the oscillation circuit, thereby suppressing the oscillation phenomenon and reducing the surge voltage. The oscillation absorption circuit is made up of the RL parallel circuit of resistance and inductance. The oscillation absorption circuit and the class-D amplifier circuit constitute the oscillation circuit, and the resistance of the oscillation absorption circuit constitutes the damping resistance of the oscillation circuit in the high RF range.

Abstract: A phase of the pulse control signal upon restarting is synchronized with the phase of the pulse control signal upon suspending, thereby suppressing fluctuations of output voltage in each phase of the inverter upon restarting and further suppressing fluctuations of voltage supplied to the load. Upon supplying DC power to a plasma generator, when arc discharge occurs in the plasma generator, supplying of the DC power is suspended to reduce damage on the electrodes and substrate, and further upon extinguishing of the arc discharge, supplying of the DC power is restarted. In suspending and resuming the DC output, the current flowing in the chopper upon suspending is held in the form of circulating current, and upon restarting the inverter, this circulating current is supplied to the load. Accordingly, it is possible to reduce a delay in supplying the DC power to the load, upon resuming the DC output.

Abstract: Intermittent short-circuit control is performed in the ignition mode, thereby allowing short-circuit current to flow in the current source step-down type chopper. Energy of the short-circuit current is temporarily accumulated in the inductor provided in the current source step-down type chopper. The accumulated energy boosts the output voltage from the direct current power supply device during the period until the next short circuiting, via the current, the multiphase inverter, and the rectifier. The voltage boosting operation where accumulation of the current energy by short circuiting and boosting of the output voltage by conduction are repeated, controls an increase of the output voltage which is applied to the plasma generator.

Abstract: Intermittent short-circuit control is performed in the ignition mode, thereby allowing short-circuit current to flow in the current source step-down type chopper. Energy of the short-circuit current is temporarily accumulated in the inductor provided in the current source step-down type chopper. The accumulated energy boosts the output voltage from the direct current power supply device during the period until the next short circuiting, via the current, the multiphase inverter, and the rectifier. The voltage boosting operation where accumulation of the current energy by short circuiting and boosting of the output voltage by conduction are repeated, controls an increase of the output voltage which is applied to the plasma generator.

Abstract: When RF power is supplied from an RF generator to a load via a power supply unit, (a) the internal impedance of the RF generator is made lower than the characteristic impedance of the power supply unit, and (b) the load-end voltage is increased by selecting the electrical length LE of the power supply unit, which connects between the RF generator and the load to supply RF power, so that the electrical length LE has a predetermined relation with the fundamental wavelength ? of the RF AC. More specifically, the electrical length LE of the power supply unit is selected in such a way that, when the load end, which is the input end of the load, is in an open state, the electrical length LE is (2n?1)·(?/4)?k·??LE?(2n?1)·(?/4)+k·? (n is an integer, k is {??2·cos?1(1/K)}/(4?)) with respect to the fundamental wavelength ? of the RF AC.

Abstract: In an RF power supply for supplying RF power to a plasma load, reflected wave power control is performed in which the reflected wave power of an RF generator is detected and the RF generator is controlled. For a short-time variation in reflected wave power, control is performed based on a peak value variation in the detection value of reflected wave power. For a long-time variation in reflected wave power, control is performed based on a variation in a smoothed value obtained by smoothing detection values of reflected wave power. A reflected wave power control loop system includes a reflected wave power peak value dropping loop system and an arc blocking system that perform control based on a peak variation in reflected wave power and a reflected wave power amount dropping loop system that performs control based on a smoothed power amount of reflected wave power.