JP6613411B1 - DC pulse power supply for plasma processing equipment - Google Patents

Abstract

A direct-current pulse power supply apparatus that suppresses power loss at a current limiting resistor and applies a pulse voltage having a favorable waveform shape to a capacitive load circuit. A DC pulse power supply device includes an LC resonance circuit including a basic voltage generation unit that determines a bottom voltage and a top voltage of a pulse voltage, and an inductance element and an output capacitor when the pulse voltage is raised and lowered. A resonance driving unit 2 that supplies or absorbs a resonance current and a pulse shaping unit 3 that improves the rising and falling characteristics of the pulse voltage by a PFN circuit are included. At the timing when the voltage at the connection point (node N1) of the output capacitor 18 rises to the vicinity of the voltage V1 due to the resonance current, the switching unit 13 is turned on and the voltage from the DC voltage source 10 starts to be applied. Thereby, the current flowing through the current limiting resistor 17 can be suppressed. In addition, the pulse waveform shape can be improved by passing through the pulse shaping unit 3 and applied to the capacitive load circuit 4. [Selection] Figure 1

Description

  The present invention relates to a DC pulse power supply device used in various plasma processing apparatuses such as a plasma etching apparatus.

Currently, in various fields including a semiconductor process, a plasma apparatus that processes an object using plasma is used.
FIG. 14 is a diagram showing a schematic configuration of an example of a conventional power supply device for driving a plasma etching apparatus. This plasma etching apparatus processes an object to be processed by applying pulsed DC power to high-frequency plasma.

  In FIG. 14, the plasma etching apparatus is a very simplified model in which two electrodes are arranged in a chamber (not shown) into which a discharge gas and a reaction gas are introduced in a vacuum atmosphere that is evacuated. It is shown. In this example, the upper electrode is a cathode electrode 721, which is an electrode for generating electric discharge plasma 723 by supplying electric power to a predetermined gas. On the other hand, the lower electrode is a counter electrode 722 that is installed facing the cathode electrode 721 so as to form a uniform electric field with the cathode electrode 721. Here, the counter electrode 722 is electrically grounded together with the chamber. The processing object is fixed to either the cathode electrode 721 or the counter electrode 722. A capacitor is formed between the cathode electrode 721 and the counter electrode 722 that are arranged apart from each other by a predetermined distance, and the capacitance of this capacitor is the plasma resistance of the discharge plasma 723 generated between the electrodes 721 and 722. To form a capacitive load circuit 72.

  The high frequency power supply 80 supplies high frequency power to the cathode electrode 721 via a coupling capacitor and an impedance matching circuit (not shown). On the other hand, the direct-current pulse power supply 60 supplies a negative direct-current pulse voltage to the cathode electrode 721. Since the direct-current pulse power supply 60 and the high-frequency power supply 80 are connected in parallel to the cathode electrode 721, the cathode electrode 721 and the direct-current pulse power supply 60 are prevented from being applied to the direct-current pulse power supply 60. A low pass filter 71 including a reactor 711 and a capacitor 712 is inserted therebetween.

  As is well known, when the discharge plasma 723 is excited by the high-frequency power source 80, a negative self-bias voltage is generated between the electrodes 721 and 722 so that the electron current and the ion current are almost equal. . The self-bias voltage at this time is considered to be applied from a DC voltage source inserted in series with the high-frequency power source 80, and the DC voltage source 81 is equivalently shown in the figure. It can be considered that the capacitive load circuit 72 and the low-pass filter 71 are charged to a predetermined self-bias voltage by the DC voltage source 81. The discharge plasma 723 can irradiate the object to be processed with high ion acceleration energy by the self-bias voltage charged in the capacitive load circuit 72.

  A conventional general DC pulse power source 60 for applying a DC pulse voltage to the capacitive load circuit 72 as described above is complementary to the DC power source 61 as shown schematically in FIG. The configuration includes two switching elements 62 and 63 that are turned off (see, for example, Patent Document 1). That is, when the two switching elements 62 and 63 are turned on and off in a complementary manner, the output voltage -V0 (generally several hundred to 1,000 V or more) of the DC power supply and the ground potential (0 V) are alternately changed to the DC pulse power supply 60. Appears, and a negative DC pulse voltage having a peak value V0 is generated. Patent Document 1 also has a configuration in which not only a DC pulse voltage is applied to the capacitive load circuit, but also energy stored in the capacitive load circuit is regenerated to the power supply device side using a switching element and a resonance circuit. It is disclosed.

JP 2018-107904 A Japanese Patent Laid-Open No. 2001-27888

  As described in FIG. 14, in the DC pulse power supply as described above, in order to prevent an excessive current (inrush current) from flowing into the switching element when the power is turned on, etc. A current limiting resistor 64 of about several Ω to several tens of Ω is provided between the output terminal of the power source and the cathode side of the capacitive load circuit 72. However, when a current limiting resistor is provided, a peak current depending on the resistance value of the current limiting resistor and the peak value of the DC pulse voltage is generated every time the voltage value of the DC pulse voltage changes during steady operation. The higher the frequency of the DC pulse voltage, the higher the frequency of peak current generation, and the effective value of the current flowing through the current limiting resistor increases. In the current limiting resistance, heat is generated due to power loss, but when the effective value of the current increases, the heat generation amount becomes considerably large. Therefore, a resistor having a considerably large size and weight is usually required as the current limiting resistor. As a result, the efficiency of the power supply device is deteriorated, the size is increased, the weight is increased, and the cost is increased.

  In particular, in the field of plasma processing such as plasma etching, there is a strong demand for improving processing accuracy. For this purpose, the characteristics of rising and falling of the DC pulse voltage applied from the DC pulse power source to the plasma etching apparatus are required. Need to improve.

  The present invention has been made to solve these problems, and the object of the present invention is to reduce the power loss in the current limiting resistor and improve the rising and falling characteristics of the DC pulse voltage. An object of the present invention is to provide a DC pulse power supply device for a plasma processing apparatus.

  The inventor of the present application has paid attention to a resonance-type power supply device disclosed in Patent Document 2 as one technique for raising and lowering a DC pulse voltage without generating a large peak current. This power supply device is used for driving a plasma display, and smoothly raises or lowers a pulse voltage by utilizing LC resonance between an inductance element and a capacitive load. However, such a conventional resonance type power supply device has a slow rise and fall speed of the pulse voltage, and is not suitable for a plasma processing apparatus. Therefore, the present inventor has made the present invention by introducing a new configuration so as to make up for the disadvantages while taking advantage of the advantages of the conventional resonance method.

In order to solve the above-mentioned problems, the present invention provides a DC pulse for a plasma processing apparatus that applies a DC pulse voltage that changes to a voltage level of 2 or more to a capacitive load circuit including an electrode that forms plasma for plasma processing. A power supply unit,
a) a pulse shaping unit in which a plurality of capacitive elements including the capacitive load circuit and a plurality of inductance elements are connected in a ladder shape;
b) a power supply unit for supplying power to the capacitive load circuit through the pulse shaping unit, including a DC voltage source that generates a first DC voltage corresponding to the highest voltage level of the DC pulse voltage; At least one of the plurality of switching units for switching the output voltage and / or the ground potential by the supply unit, the output capacitor connected between the input end and the ground end of the pulse shaping unit, and the plurality of switching units is conducted. Current path when power is supplied from the power supply unit to the capacitive load circuit, and a path through which at least one other of the plurality of switching units is conducted and current by the accumulated energy of the output capacitor flows. A basic current for inputting a voltage switched by the plurality of switching units to an input terminal of the pulse shaping unit. A generation unit,
c) A resonance inductance element having one end connected to the input end of the pulse shaping unit, a first switching unit and a second switching unit are connected in series, and between the first switching unit and the second switching unit. A series circuit portion to which the other end of the resonance inductance element is connected, and a resonance first DC that applies a second DC voltage lower than the first DC voltage to the high voltage side end of the series circuit portion. A resonance driving unit including: a voltage source; and a second DC voltage source for resonance that applies a predetermined third DC voltage lower than the second DC voltage to the low voltage side end of the series circuit unit;
d) Controlling on / off operations of the plurality of switching units of the basic voltage generation unit and the first and second switching units of the resonance driving unit, and at the time of starting up the DC pulse voltage, After turning on the first switching unit of the driving unit and increasing the voltage at the input end of the pulse shaping unit by LC resonance between the resonance inductance element and the output capacitor and / or the capacitance of the pulse shaping unit, A predetermined switching unit of the basic voltage generation unit is turned on to apply the first DC voltage from the power supply unit to the input terminal of the pulse shaping unit, and when the DC pulse voltage falls, from the basic voltage generation unit The voltage application is stopped and the second switching unit of the resonance driving unit is turned on, and the resonance inductance element, the output capacitor, and / or the pulse adjustment unit are turned on. After the voltage at the input end of the pulse shaping unit is reduced by LC resonance with the capacitance of the unit, the predetermined switching unit of the basic voltage generation unit is turned on and the potential after falling is set to the input end of the pulse shaping unit A control unit for controlling the operation of each of the switching units,
It is characterized by having.

  In the DC pulse power supply device for a plasma processing apparatus according to the first aspect of the present invention, the current limiting resistor has a voltage output terminal that outputs a voltage by switching the plurality of switching units and an input terminal of the pulse shaping unit. Connected between.

  Further, in the DC pulse power supply device for a plasma processing apparatus according to the first aspect of the present invention, the current limiting resistor is a low voltage side end portion in a low voltage side switching portion among the plurality of switching portions connected in series. The power supply unit supplies power to both ends of the plurality of switching units connected in series.

  The main difference between the first mode and the second mode is the insertion position of the current limiting resistor. In the second mode, the current limiting resistor provided in the first mode is short-circuited, and a plurality of current limiting resistors are short-circuited. A current limiting resistor is provided between the switching part on the low voltage side of the switching part and the ground part, and power is supplied to both ends of the plurality of switching parts, that is, to both ends of the series circuit including no current limiting resistance. Power is supplied by the unit. The other basic configuration is the same between the first and second aspects.

  In the present invention, the configuration of the LC filter provided in the output stage of the DC pulse power supply apparatus (or the voltage input stage of the plasma processing apparatus) in order to prevent the high frequency voltage from entering from the capacitive load circuit side to the DC pulse power supply apparatus side. The element can be used as a part of the capacitive element and the inductance element included in the pulse shaping unit. Further, parasitic inductance, parasitic capacitance, and the like in wiring such as a coaxial cable connecting the DC pulse power supply device and the plasma processing apparatus can also be used as part of the capacitive element and the inductance element included in the pulse shaping unit.

  In a typical embodiment of the present invention, the DC pulse voltage is a rectangular wave voltage having two voltage levels: a ground potential (0 V) and a predetermined potential that is not the ground potential. In another embodiment of the present invention, the DC pulse voltage is a rectangular wave voltage having two voltage levels of two predetermined potentials that are not ground potentials. In still another embodiment of the present invention, the DC pulse voltage is a multi-stage rectangular wave voltage having a predetermined three or more voltage levels including or not including the ground potential.

  Consider a case where the DC pulse voltage applied to the capacitive load circuit is a rectangular wave voltage of two voltage levels, a ground potential and a predetermined potential V1. In this case, the basic voltage generation unit includes one DC voltage source and two switching units. When the DC pulse voltage is raised from the potential 0 to the potential V1, no voltage is applied from the basic voltage generation unit to the input terminal of the pulse shaping unit, and the LC switching resonance is performed by turning on the first switching unit in the resonance driving unit. Is supplied to the output capacitor to charge the output capacitor. As a result, the voltage at the input end of the pulse shaping unit rises. After the voltage rises sufficiently due to the resonance current, the switching operation of the switching unit is performed in the basic voltage generation unit, the output voltage from the DC voltage source is applied to the input end of the pulse shaping unit, and the potential of the input end is predetermined. Is maintained at the potential V1.

  On the other hand, when the DC pulse voltage is lowered from the potential V1 to 0, voltage application from the basic voltage generation unit to the input terminal of the pulse shaping unit is stopped, and the second switching unit is turned on in the resonance driving unit. The resonance current due to the LC resonance flows through the resonance inductance element in the opposite direction to charge the capacitor included in the resonance second DC voltage source, for example. That is, the electric charge accumulated in the output capacitor until immediately before is transferred to the capacitor. As a result, the potential at the input end of the pulse shaping unit drops to near zero, and after the voltage has sufficiently dropped, the other switching unit is turned on in the basic voltage generating unit, so that the potential at the input end of the pulse shaping unit is Fixed to 0.

  Thus, in the DC pulse power supply device according to the present invention, little or no current flows through the current limiting resistor in the basic voltage generator at the rise and fall of the DC pulse voltage. Therefore, the effective value of the current flowing through the current limiting resistor is small, and heat generation due to power loss at the resistor can be suppressed.

  Further, the speed of voltage increase and decrease at the input terminal of the pulse shaping unit is restricted by the resonance wavelength of the resonance current. Therefore, although the voltage change at the input terminal of the pulse shaping unit is slow, the pulse shaping unit which is a pulse forming network (PFN) improves the rising and falling characteristics of the pulse waveform. As a result, a DC pulse voltage having a good waveform shape with a sharp rise and fall is applied to the capacitive load circuit, that is, the plasma generation electrode of the plasma processing apparatus.

  In the second mode, since the current limiting resistor is arranged on the low voltage side, it is not necessary to consider the capacity of the current limiting resistor in terms of space, creepage, and ground. Therefore, there is an accompanying effect that restrictions on the arrangement and structure of components and circuits can be relaxed.

  In the second aspect, in the series circuit unit of the resonance driving unit, two forward connection diodes are connected in series between the first switching unit and the second switching unit, and between the two diodes. The other end of the resonance inductance element is connected to a diode connected in a forward direction from the end of the current limiting resistor on the switching unit side to the connection end of the first switching unit and the diode. A diode connected in a forward direction from a connection end of the second switching unit and the diode to a high voltage side end of the plurality of switching units connected in series in the basic voltage generation unit. It is good to have a structure provided.

  In this configuration, the diode included in the series circuit unit of the resonance driving unit has a function of preventing a reverse current in the resonance operation, but generates a recovery current due to accumulated charges at the time of commutation. Due to the energy generated in the resonance inductance element by this recovery current, a high surge voltage may be applied to the diode or the switching unit. On the other hand, the two diodes provided between the series circuit unit of the resonance drive unit and the basic voltage generation unit function as freewheel diodes and continue to flow the recovery current that has flowed through the resonance inductance element. This prevents a high voltage surge from being applied to the reverse current blocking diode and the switching unit, and eliminates the need to provide a snubber circuit for absorbing the surge.

  Further, in the DC pulse power supply device according to the present invention, in order to minimize the current flowing through the current limiting resistor when the DC pulse voltage rises and falls, the charging voltage of the output capacitor due to the resonance current is switched in the basic voltage generator. It is preferable to perform the switching operation of the switching unit in the basic voltage generation unit when the voltage is equal to the voltage output by switching the unit and when the charging voltage of the output capacitor discharged by the resonance current is equal to 0.

  Therefore, in the DC pulse power supply device according to the present invention, the control unit includes a detection unit that detects a current value flowing through the resonance inductance element, and the basic voltage generation unit switches the switching unit based on the detection result by the detection unit. It is preferable to determine the timing for switching between.

  In general, the charging voltage of the output capacitor reaches the maximum value at time 0 after the resonance current exhibits a substantially sinusoidal half-wave shape during the half cycle of LC resonance. Therefore, in a state where the second DC voltage and the third DC voltage in the resonance driving unit are appropriately determined with respect to the first DC voltage in the basic voltage generation unit, the resonance current changes to a substantially sinusoidal half-wave shape. It is preferable to switch the switching unit in the basic voltage generation unit at time 0. That is, when the charging voltage of the output capacitor reaches or is closest to the first DC voltage due to the resonance current, switching to voltage application from the basic voltage generation unit is preferable. Thereby, the electric current which flows into a current limiting resistor can be decreased further, and the heat_generation | fever can be suppressed.

  As described above, LC resonance occurs and resonance current flows as the switching unit of the resonance driving unit is turned on / off, but resonance energy is attenuated due to power consumption by the plasma resistance of the capacitive load circuit. As the resonance energy is attenuated, the maximum charging voltage of the output capacitor at the time of charging is lowered, and conversely, the charging voltage of the output capacitor is not completely lowered at the time of discharging.

  Therefore, in the DC pulse power supply device according to the present invention, the second DC voltage is set higher than 1/2 of the first DC voltage, and the third DC voltage is lower than 1/2 of the first DC voltage. It may be configured to be set.

  The voltage difference between the second DC voltage and 1/2 of the first DC voltage, and the voltage difference between the third DC voltage and 1/2 of the first DC voltage are appropriately set according to the magnitude of the load resistance. By determining, it is possible to compensate for the shortage of voltage due to the attenuation of the resonance energy described above. Thereby, it is possible to further reduce the current flowing through the current limiting resistor when shifting to the voltage application from the basic voltage generating unit and vice versa.

  That is, in the DC pulse power supply device according to the present invention, the first DC voltage source for resonance and the second DC voltage source for resonance are each in accordance with a load current flowing through a load resistor in the capacitive load circuit. A voltage difference between 1/2 of the first DC voltage and the second DC voltage, and a voltage difference between 1/2 of the first DC voltage and the third DC voltage may be determined.

  In a plasma processing apparatus such as a plasma etching apparatus, the magnitude of the load resistance varies depending on the plasma generation conditions, etc., so a current detector for detecting the load current is provided, and the voltage difference is determined according to the detected load current. The current flowing through the current limiting resistor can be reduced regardless of the load resistance.

  Further, as described above, in order to change the second DC voltage and the third DC voltage according to the load current, in the DC pulse power supply device according to the present invention, the resonance first DC voltage source and the resonance second DC voltage source. Each of the DC voltage sources may include a boost converter, a buck converter, or a buck-boost converter that can adjust the output voltage.

  According to the direct-current pulse power supply device according to the present invention, it is possible to reduce the power loss at the current limiting resistor and reduce the heat generation. Thereby, the size and weight of the resistor used as the current limiting resistor can be reduced, and a low-cost resistor can be used. As a result, the size and weight of the power supply device itself can be reduced and the device cost can be reduced. Further, according to the DC pulse power supply device according to the present invention, the DC pulse voltage having a good waveform shape with a steep rise and fall is reduced while reducing the power loss at the current limiting resistor. Can be supplied to the circuit. Thereby, it is possible to improve the accuracy of processing and processing using plasma in the plasma processing apparatus.

1 is a schematic configuration diagram of a DC pulse power supply device according to a first embodiment of the present invention. The more detailed block diagram of the DC pulse power supply device which is 1st Embodiment. The operation | movement waveform diagram of the principal part of the direct-current pulse power supply device which is 1st Embodiment. The figure which shows the simulation result of the voltage change of the DC pulse power supply device which is 1st Embodiment, and an electric current change. The schematic block diagram of the DC pulse power supply device which is the 2nd Embodiment of this invention. The figure which shows an example of the waveform of the direct current | flow pulse voltage applied to load in the direct current | flow pulse power supply device which is 2nd Embodiment. The schematic block diagram of the DC pulse power supply device which is the 3rd Embodiment of this invention. The figure which shows an example of the waveform of the direct current | flow pulse voltage applied to load in the direct current | flow pulse power supply device which is 3rd Embodiment. The lineblock diagram of the direct-current pulse power supply device which is a modification of a 1st embodiment. The lineblock diagram of the direct-current pulse power supply device which is a modification of a 1st embodiment. The lineblock diagram of the direct-current pulse power supply device which is a modification of a 1st embodiment. FIG. 12 is a detailed configuration diagram of a DC pulse power supply device in which the modification shown in FIG. 11 is further improved. FIG. 13 is an operation waveform diagram of the main part of the DC pulse power supply device shown in FIG. 12. The schematic block diagram of an example of the conventional power supply device for plasma apparatuses.

[First Embodiment]
A DC pulse power supply device for a plasma processing apparatus according to a first embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a basic circuit configuration diagram of a DC pulse power supply device according to the first embodiment, and FIG. 2 is a more detailed configuration diagram of the DC pulse power supply device according to the first embodiment. FIG. 3 is an operation waveform diagram of the main part of the DC pulse power supply device according to the first embodiment.

The DC pulse power supply device of the first embodiment applies a DC pulse voltage to the capacitive load circuit 4 including an electrode for plasma generation in a plasma etching apparatus. Here, the capacitive load circuit 4 is simply shown as a parallel circuit of a capacitor 40 and a resistor 41. In general, in a plasma etching apparatus, a negative DC pulse voltage is often applied to a plasma generation electrode. Here, for convenience of explanation, a positive polarity is applied to the capacitive load circuit 4 including the plasma generation electrode. Description will be made assuming that a DC pulse voltage is applied.
The DC pulse power supply device includes a basic voltage generation unit 1, a resonance drive unit 2, a pulse shaping unit 3, and a control unit 5.

  The basic voltage generator 1 determines two voltage levels of the DC pulse voltage applied to the capacitive load circuit 4, that is, the voltage on the pulse top side and the voltage on the pulse bottom side. As shown in FIGS. 1 and 2, the basic voltage generator 1 includes a first DC voltage source 10, a third diode 11, a voltage source capacitor 12, a first switching unit 13, a first diode 14, and a second switching unit 15. , A second diode 16, a current limiting resistor 17, and an output capacitor 18.

  The first DC voltage source 10 outputs a positive DC voltage (voltage value: V1), and is connected to the voltage source capacitor 12 and the first switching unit 13 via the third diode 11 which is forward-connected. It is connected to one end of a series circuit with the second switching unit 15. The other end of the series circuit is grounded. The first diode 14 is connected to the first switching unit 13 and the second diode 16 is connected to the second switching unit 15 in antiparallel. The current limiting resistor 17 is connected between a connection point between the first switching unit 13 and the second switching unit 15 and a node N1 to which a resonance inductance element 200 and an output capacitor 18 described later are connected. ing.

  As shown in FIG. 1, the resonance driving unit 2 includes a resonance first DC voltage source 20, a resonance first switching unit 21, a fourth diode 22, a fifth diode 23, a sixth diode 24, and a resonance second switching. Part 25, seventh diode 26, voltage source capacitor 27, eighth diode 28, resonance second DC voltage source 29, and resonance inductance element 200. The resonance first DC voltage source 20 outputs a positive DC voltage. Between the output terminals of the resonance first DC voltage source 20, the resonance first switching unit 21, the fifth diode 23, A series circuit in which the sixth diode 24 and the second switching unit for resonance 25 are connected in series is connected. The fifth diode 23 and the sixth diode 24 are reverse blocking diodes for individually flowing a half wave of the resonance current through the resonance inductance element 200.

  The fourth diode 22 is connected to the first resonance switching unit 21 and the seventh diode 26 is connected to the second resonance switching unit 25 in antiparallel. The resonance second DC voltage source 29 outputs a positive DC voltage (voltage value: V3), and is connected to the voltage source capacitor 27 and the resonance first via the eighth diode 28 which is forward-connected. It is connected to a node N2 that is a connection point between the DC voltage source 20 and the second switching unit 25 for resonance. A resonance inductance element 200 is connected between the node N3 which is a connection point of the two diodes 23 and 24 and the node N1. In FIG. 2, the configurations of the resonance first DC voltage source 20, the resonance second DC voltage source 29, and the like are described more specifically, which will be described later.

  The pulse shaping unit 3 includes, for example, three inductance elements 30, 32, 34 and two capacitors 31, 33, and coupled with a capacitor 40 included in the capacitive load circuit 4, a pulse forming network (LC concentrated distribution circuit) PFN = Pulse Forming Network) circuit.

  In an actual system in which a plasma etching apparatus and a DC pulse power supply apparatus are connected, the inductance elements 30, 32 and 34 and capacitors 31 and 33 included in the pulse shaping unit 3 are necessarily present in the casing of the DC pulse power supply apparatus. It does not have to be an element. Specifically, the plasma etching apparatus and the DC pulse power supply apparatus are generally connected by a coaxial cable line, and the coaxial cable line has a relatively large inductance component and capacitance component. Further, as described above, the plasma etching apparatus is provided with a filter including an inductance element and a capacitor in order to avoid applying a high frequency voltage applied to the plasma generating electrode to the DC pulse power supply apparatus side. Yes. Such an inductance component and a capacitance component in the coaxial cable line and the filter can be used for the inductance elements 30, 32, and 34 and the capacitors 31 and 33. Of course, in order to adjust the inductance and capacitance, in addition to the coaxial cable line and the filter, an inductance element and a capacitor may be appropriately added.

  1 and 2, the inductance element 30 is the inductance component of the coaxial cable line, the inductance elements 32 and 34 and the capacitor 33 are the inductance component and capacitance component of the high frequency voltage blocking filter, and the capacitor 31 is the capacitance of the coaxial cable line. The sum of the component and the capacitance component of the high frequency voltage blocking filter is assumed.

  Each switching unit 13, 15, 21, 25 is composed of a semiconductor switching element such as a power MOSFET, and its on / off operation is controlled by control signals G 1, G 2, G 3, G 4 respectively input from the control unit 5. The control unit 5 includes a microcomputer (microcomputer) including, for example, a CPU, a ROM, a RAM, a timer, and the like, and generates and outputs the control signals by executing processing according to a program given in advance. The current detection unit 51 attached to the control unit 5 detects a current flowing through the resonance inductance element 200 and inputs the detection signal to the control unit 5.

2, the configuration of the DC voltage sources 10, 20, 29 in FIG. 1 is shown more specifically. 2, the same reference numerals as those in FIG. 1 denote the same components.
The first DC voltage source 10 in FIG. 1 has a configuration in which two DC voltage sources 10A and 10B whose output voltages are both (1/2) V1 = V4 in FIG. A DC voltage having a voltage value V1 obtained by adding the output voltages of the two DC voltage sources 10A and 10B is applied to. On the other hand, the output voltage (voltage value: V4) of the DC voltage source 10B is generated by a boost converter including an inductance element 212, diodes 204 and 205, a switching unit 203, and a capacitor 202, and two switching units 207 and 209 connected in series. , Diodes 208 and 210, inductance element 211, and bidirectional buck-boost converter including capacitor 206.

  That is, the resonance second DC voltage source 29 in FIG. 1 is constituted by a combination of the DC voltage source 10B and the bidirectional buck-boost converter in FIG. Further, a voltage V2 applied to one end of the resonance first switching unit 21 in which the output voltage of the resonance first DC voltage source 20 and the output voltage of the resonance second DC voltage source 29 in FIG. 2 is generated by the combination of the DC voltage source 10B and the boost converter in FIG. The bidirectional buck-boost converter functions as a step-down converter when converting voltage from the DC voltage source 10B side to the resonance second switching unit 25 side. The step-up converter and the bidirectional step-up / step-down converter are obtained by boosting a voltage having a voltage value of V4 by the duty ratio of a control signal supplied from the control unit 5 to turn on or off one or two switching units. Is a voltage obtained by stepping down a voltage having a voltage value of V3 and a voltage having a voltage value of V4. That is, V2 = V4 + Va when the boosted voltage in the booster converter is Va, and V3 = V4−Vb when the reduced voltage when the bidirectional buck-boost converter functions as a buck converter is Vb.

The operation of the apparatus of this embodiment will be described with reference to the operation waveform diagram shown in FIG.
Prior to time t0, only the control signal G2 is at the H level and the second switching unit 15 is in the on state, the control signals G1, G3, and G4 are at the L level, and the other switching units 13, 21, and 25 are in the off state. At this time, the node N1 is grounded through the current limiting resistor 17 and the second switching unit 15 in the on state, and the voltage applied to the capacitive load circuit 4 is zero. Further, the node N2 of the resonance driving unit 2 is fixed to the voltage V3 by the second DC voltage source 29 and the voltage source capacitor 27.

  At time t0, the control signal G3 changes to H level, and the control signal G2 changes to L level. As a result, the second switching unit 15 is turned off, and the resonance first switching unit 21 is turned on instead. Then, the voltage V2 obtained by adding the output voltage of the first DC voltage source for resonance 20 and the output voltage of the second DC voltage source for resonance 29 is added via the inductance element 200 to the output capacitor 18, the pulse shaping unit 3, and Applied to the capacitive load circuit 4. Since the load viewed from the node N3 is an LC resonance circuit, the capacitive load circuit 4 passes through the inductance element 200 during the α1 period between t0 and t1 (t1 is a timing when the first switching unit 13 is turned on). A substantially sinusoidal half-wave resonance current Lo (i) flows (see FIG. 3E). Since this resonance current charges the output capacitor 18, the voltage Co (v) across the output capacitor 18 changes to Lo (v) + V2.

  Assuming that Va = 0 and V2 = V4 = (1/2) V1, and the resistance 41 of the capacitive load circuit 4 can be ignored, the voltage across the output capacitor 18 from 0 during the resonance half-cycle period α1. Change to reach V1. In practice, however, the resonance energy decreases due to power consumption by the resistor 41 included in the capacitive load circuit 4. Therefore, if V2 = (1/2) V1, the charging voltage Co (v) of the output capacitor 18 changes as shown by the broken line in FIG. 3 (f), and even at the end of the period α1 of the resonance half cycle. It cannot rise to voltage V1. Therefore, in the apparatus of the present embodiment, instead of setting V2 = (1/2) V1, the decrease in resonance energy is compensated by increasing V2 by Va rather than (1/2) V1, and the charging voltage is increased. Co (v) reaches almost V1.

  The control unit 5 determines the timing of t1, which is the end point of the α1 period, based on the change in the current Lo (i) detected by the current detection unit 51. At time t1, the voltage value of the charging voltage Co (v) of the output capacitor 18 should have reached V1, and at this time, the control signal G1 is changed to H level. Then, the first switching unit 13 is turned on, and the output of the first DC voltage source 10 (10A) and the high voltage side terminal of the voltage source capacitor 12 are connected to the node N1 via the current limiting resistor 17, and the voltage is applied to the node N1. A voltage of value V1 is applied.

  When the voltage value of the charging voltage Co (v) of the output capacitor 18 is lower than V1 when the first switching unit 13 is turned on, the first switching unit 13 passes through the first switching unit 13 as shown by a broken line in FIG. Since a large and steep charging current Rd (i) flows, a large power loss occurs in the current limiting resistor 17. Conversely, when the voltage value of the charging voltage Co (v) of the output capacitor 18 is higher than V1, the power source regenerative current is supplied to the voltage source capacitor 12 via the current limiting resistor 17 and the body diode of the first switching unit 13. Flows. Therefore, also in this case, power loss occurs in the current limiting resistor 17. For this reason, detection of the end timing of α1 and appropriate setting of Va are particularly important for suppressing power loss in the current limiting resistor 17.

  The control unit 5 changes the control signal G3 to L level after a predetermined time has elapsed after changing the control signal G1 to H level, and turns off the resonance first switching unit 21. Due to the blocking action of the fifth diode 23, the resonance current Lo (i) flows only in the period of the resonance half-wave α1 in the period from to to t2. Therefore, the timing for ending the on-period β1 of the resonance first switching unit 21 may be any time between time t1 and time t2. When the first switching unit 13 is on, the voltage level of the DC pulse voltage applied to the capacitive load circuit 4 is fixed at V1. At this time, the voltage source capacitor 12 (or the first DC voltage source 10) passes through the first switching unit 13, the current limiting resistor 17, the inductance elements 30, 32, and 34, passes through the capacitive load circuit 4, and passes through the ground. A current path returning to the capacitor 12 (or the first DC voltage source 10) is formed. Accordingly, the current Rd (i) flowing through the current limiting resistor 17 is substantially equal to the load current Rp (i) flowing through the resistor 41 of the capacitive load circuit 4 (see FIG. 3G). Since the load current Rp (i) is small, the current Rd (i) flowing through the current limiting resistor 17 is also small, and heat generation hardly causes a problem.

  After that, at time t2, the control unit 5 changes the control signal G1 to L level and changes the control signal G4 to H level. Then, the first switching unit 13 is turned off and the resonance second switching unit 25 is turned on. As a result, the output voltage (voltage value: V2) of the resonance second DC voltage source 29 is applied to the node N3, and the resonance including the resonance inductance element 200, the output capacitor 18, the pulse shaping unit 3, and the capacitive load circuit 4 is achieved. A resonance current Lo (i) flows from the circuit toward the resonance second DC voltage source 29, that is, through the resonance inductance element 200 in the opposite direction to that during the α1 period. This resonance current Lo (i) flows only during the period of α2, which is a half cycle of resonance, as shown in FIG. The resonance current is charged to the voltage source capacitor 27 corresponding to the resonance second DC voltage source 29 through the sixth diode 24 and the resonance second switching unit 25.

  When the resonance current flows during the period α2, the charging voltage Co (v) of the output capacitor 18 becomes V3−Lo (v). Assuming that Vb = 0 and V3 = V4 = (1/2) V1, and the resistance 41 of the capacitive load circuit 4 can be ignored, the voltage across the output capacitor 18 from V1 during the resonance half-cycle period α2. Change to zero. However, as described above, the resonance energy actually decreases due to power consumption by the resistor 41 included in the capacitive load circuit 4. Therefore, assuming that V3 = (1/2) V1, the charging voltage Co (v) of the output capacitor 18 changes as shown by the broken line in FIG. 3 (f), and even at the end of the period α2 of the resonance half cycle. Does not drop to zero. Therefore, in the apparatus of the present embodiment, instead of setting V3 = (1/2) V1, V3 is reduced by Vb from (1/2) V1 to compensate for the decrease in resonance energy due to power consumption, The charging voltage Co (v) is reduced to almost zero.

  Based on the change in the current Lo (i) detected by the current detector 51, the controller 5 determines the timing of t3, which is the end point of the α2 period. At time t3, the voltage value of the charging voltage Co (v) of the output capacitor 18 should be lowered to near 0, and at this time, the control signal G2 is changed to H level. Then, the second switching unit 15 is turned on, the node N1 is grounded, and the voltage of the node N1 becomes the ground potential.

  At this time, if the voltage value of the charging voltage Co (v) of the output capacitor 18 is higher than 0, a large and steep charging current Rd (i) is passed through the second switching unit 15 as indicated by a broken line in FIG. ) Flows, a large power loss occurs in the current limiting resistor 17. Conversely, when the voltage value of the charging voltage Co (v) of the output capacitor 18 is lower than 0, a short-circuit current flows through the resonance circuit through the body diode of the second switching unit 15 via the current limiting resistor 17. Therefore, also in this case, power loss occurs in the current limiting resistor 17. For this reason, the detection of the end timing of α2 and the appropriate setting of Vb are particularly important for suppressing power loss in the current limiting resistor 17 when the pulse voltage falls.

  The control unit 5 changes the control signal G4 to L level after a predetermined time has elapsed after changing the control signal G2 to H level, and turns off the resonance second switching unit 25. Due to the blocking action of the sixth diode 24, the resonance current Lo (i) flows only in the period of the resonance half-wave α2 in the period from t2 to t0. Therefore, the timing for ending the on period β2 of the resonance second switching unit 25 may be any time between time t3 and time t0. In the state where the second switching unit 15 is on, the voltage level of the DC pulse voltage applied to the capacitive load circuit 4 is fixed to 0, and almost no current flows through the current limiting resistor 17.

  In the configuration shown in FIG. 1, as described above, the voltage source capacitor 27 is charged with the resonance current, so that the resonance energy is regenerated and accumulated in the capacitor 27. By such energy regeneration, the power supplied from the resonance second DC voltage source 29 can be saved, and the efficiency of the power supply can be improved. Further, as shown in FIG. 2, in the configuration in which the bidirectional buck-boost converter is used as the second DC voltage source 29 for resonance, the capacitor is generated by the resonance current flowing through the switching unit 25 when the second switching unit 25 is turned on. 206 is charged, but the bidirectional buck-boost converter performs voltage control to boost the charging voltage of the capacitor 206 and charge the capacitor 27. That is, in this case, energy corresponding to an increase from the voltage value V3 stored in the capacitor 206 is regenerated and stored in the capacitor 27. Such energy regeneration can save power supplied from the DC voltage source 10B.

  Note that the optimum value of the voltage increase Va and the voltage decrease Vb for compensating for the loss of resonance energy in the load resistor 41 varies depending on the value of the resistor 41. The value of the resistor 41 depends on plasma generation conditions and the like, and also depends on the plasma state. Therefore, preferably, the control unit 5 has a voltage value V1 at a high voltage level of the DC pulse voltage, an average value of the current (load current) output from the first DC voltage source 10 (10A and 10B), and the first value. The value of the resistor 41 is estimated based on the duty ratio of the control signal G1 that drives the switching unit 13, and the values of Va and Vb are determined based on the estimated value, and V2 and V3 are set. What is necessary is just to detect the electric current which flows into the inductance element 19, for example for the average value of an electric current. The voltage value V1 may be an actual detection value, but may be a set value (target value) in the first DC voltage source 10.

  As described above, in the apparatus according to the present embodiment, it is possible to reduce a current flowing through the current limiting resistor 17 and suppress a useless power loss. Thereby, the amount of heat generated by the current limiting resistor 17 is reduced, and a small and inexpensive resistor can be used.

  In the apparatus of this embodiment, the rising and falling speeds of the DC pulse voltage at the node N1 depend on the resonance wavelength of the resonance current, but it is difficult to increase the speed by shortening the resonance wavelength due to the limitation of the resonance constant. . On the other hand, in the apparatus of the present embodiment, the pulse shaping unit 3 which is a PFN circuit improves the rising and falling of the DC pulse voltage and applies a DC pulse voltage having a favorable waveform shape to the capacitive load circuit 4. .

The result of circuit simulation for confirming the effect of pulse shaping of the pulse shaping unit 3 in the circuit configuration shown in FIG. 2 will be described. The circuit constants of the main part in the circuit simulation are as follows.
-Resistance value of current limiting resistor 17: 2Ω
・ Inductance of the resonant inductance element 200: 2 uH
・ Capacitance of output capacitor 18: 1200pF
-Inductance of each inductance element 30, 32, 34 of the pulse shaping part 3: 0.9uH
・ Capacitance of capacitor 31 of pulse shaping unit 3: 800 pF (300 pF + 500 pF)
・ Capacitance of capacitor 33 in pulse shaping unit 3: 500 pF
・ Capacitance of capacitive load circuit 4: 350pF
・ Resistance of capacitive load circuit 4: 500Ω
・ DC pulse voltage generation cycle: 400kHz

Although the above circuit constant is a result of optimization to some extent, it is not necessarily the best state. 4A shows the potential Co (v) at the connection point of the output capacitor 18 on the output voltage line of the pulse shaping unit 3, the potential Cn + Cf2 (v) at the connection point of the capacitor 31, and the potential Cf1 at the connection point of the capacitor 33. FIG. (v) is a result of simulating changes in the potential Rp (v) at the connection point of the capacitive load circuit 4. FIG. 4B shows a current Lo (i) flowing through the resonance inductance element 200, a current Ln (i) flowing through the inductance element 30, a current Lf2 (i) flowing through the inductance element 32, and a current Lf1 flowing through the inductance element 34. It is the result of simulating the change of (i). FIG. 4 shows that the rising and falling characteristics of the DC pulse voltage waveform are reliably improved.
As described above, in the apparatus according to the present embodiment, a DC pulse voltage having a steep rise and fall can be applied to the capacitive load circuit 4.

[Modification of First Embodiment]
In the apparatus of the first embodiment, the configuration of the power supply unit for applying the voltages V2 and V3 across the series circuit including the resonance first switching unit 21 and the resonance second switching unit 25 in the resonance driving unit 2 is described. Can be variously modified.
In the example shown in FIG. 9, the output voltage of the first DC voltage source 10 that generates the voltage value V1 is stepped down by the step-down converter to generate the voltage value V2 (= (1/2) V1 + Va). The same output voltage is stepped down by a bidirectional buck-boost converter to generate a voltage value V3 (= (1/2) V1-Vb).
In the example shown in FIG. 10, the output voltage whose voltage value of the DC voltage source 29 is V4 (= (1/2) V1) is boosted by the boost converter and the voltage value V2 (= (1/2) V1 + Va). And the same output voltage is stepped down by a bidirectional buck-boost converter to generate a voltage value V3 (= (1/2) V1-Vb).

  As described above, if the voltages V2 and V3 are applied to both ends of the series circuit including the resonance first switching unit 21 and the resonance second switching unit 25, respectively, and the resonance energy can be regenerated to the power source side, The combination of the DC voltage source, the boost converter, the buck converter, and the bidirectional buck-boost converter can be determined as appropriate.

  In the device of the first embodiment, the current limiting resistor 17 is connected between the connection point between the first switching unit 13 and the second switching unit 15 and the node N1. It is also possible to change the insertion position. FIG. 11 is a schematic configuration diagram of a modified example in which the insertion position of the current limiting resistor 17 is changed.

  In this example, a connection point between the first switching unit 13 and the second switching unit 15 and the node N1 are directly connected, while a current limiting resistor 17 is inserted between one end of the second switching unit 15 and the ground potential. Yes. Furthermore, the low voltage side terminal of the voltage source capacitor 12, which is a power supply capacitor, is connected to the connection point between the second switching unit 15 and the current limiting resistor 17 instead of the ground potential. In this configuration, when the first switching unit 13 is in the on state and the second switching unit 14 is in the off state, the capacitive load circuit 4 passes from the voltage source capacitor 12 through the first switching unit 13 and the inductance elements 30, 32, and 34. , A current path is formed through the ground, through the current limiting resistor 17 and back to the voltage source capacitor 12. Further, when the voltage source capacitor 12 is charged by the first DC voltage source 10, a current path is formed that returns to the first DC voltage source 10 through the voltage source capacitor 12, the current limiting resistor 17, and the ground. Furthermore, when the first switching unit 13 is in the off state and the second switching unit 14 is in the on state, and the potential of the node N1 (charging voltage of the output capacitor 18) is higher than 0V, the discharge current generated by the output capacitor 18 Is formed through the second switching unit 14 and the ground to return to the output capacitor 18. That is, in the configuration shown in FIG. 11, each of the current paths includes the current limiting resistor 17.

  In this modification, since the current limiting resistor 17 is arranged on the low voltage side (ground potential side), consideration is given to the capacity of the current limiting resistor 17 between the space, the creepage, and the grounded portion. There is no need to do it. Therefore, restrictions on the arrangement and structure of components and circuits can be relaxed. Further, as described above, the current supplied from the first DC voltage source 10 and charging the voltage source capacitor 12 and the discharge from the voltage source capacitor 12 flow into the input terminal of the pulse shaping unit 3 through the first switching unit 13. The current fed back through the capacitive load circuit 4 flows to the current limiting resistor 17 at the same time. Therefore, since at least a part of such current is canceled, there is an advantage that the power loss in the current limiting resistor 17 can be reduced by reducing the current flowing through the current limiting resistor 17.

  Furthermore, a modified example in which the configuration in which the current limiting resistor 17 is arranged on the low voltage side is further improved can be employed. FIG. 12 is a detailed configuration diagram of a DC pulse power supply device to which this improvement is added. FIG. 13 is an operation waveform diagram of the main part of the DC pulse power supply device shown in FIG. In FIG. 12, the configuration of the DC voltage source 10, the resonance first DC voltage source 20, the resonance second DC voltage source 29, etc. in FIG. Although a part of the configuration is different from that shown in FIG. 2, the basic operation thereof is the same as that already described, and the description thereof is omitted.

  Generally, as a characteristic of a diode, when a reverse bias voltage is suddenly applied from a state where current is applied in the forward direction, a recovery current is generated due to accumulated charges, and a recovery period is required until the normal state is restored. well known. This phenomenon also occurs in the reverse blocking diodes 23 and 24 in the resonance drive unit 2 described in FIGS. As shown in FIG. 13 (e), when the polarity of the voltage applied to both ends of the resonance inductance element 200 is reversed at time t1 when the half wave of the resonance current ends from time t0, the current in the reverse direction by the diode 23 is reversed. Is prevented and the resonance current Lo (i) should be zero. However, in reality, a recovery current flows through the diode 23 in the reverse direction. Similarly, a recovery current from the diode 24 flows at time t3. Although the magnitude of the recovery current depends on the characteristics of the diode, it is difficult to suppress the generation by only selecting the diode.

  In the case of the configuration shown in FIG. 11, due to the energy generated in the resonance inductance element 200 by this recovery current, the switching unit 21 that is turned off complementarily with the diodes 23 and 24 reversely recovered after the recovery period has elapsed, 25, a high voltage surge may be applied. That is, a high voltage surge may be applied to the diode 23 and the switching unit 25 at time t1, and a diode 24 and the switching unit 21 at time t3. Although this can be avoided by providing a snubber circuit for absorbing a high voltage surge, problems such as a reduction in power supply efficiency due to the loss of the snubber circuit and an increase in the size of the device for securing circuit installation space arise.

  On the other hand, in the apparatus shown in FIG. 12, the connection point between the switching unit 15 and the current limiting resistor 17 is connected to the connection point between the switching unit 21 and the diode 23 and between the switching unit 25 and the diode 24. Forward-connected diodes 220 and 221 are provided as free-wheeling diodes from the connection point to the high voltage side end of the switching unit 13, respectively. These free wheel diodes continue to flow current in the same direction as immediately after the reversal when the polarity of the voltage applied to both ends of the resonance inductance element 200 is reversed as described above. It is for making.

  That is, when the switching unit 21 is turned on at time t0, a half-wave resonance current flows through the path of capacitor 202 → switching unit 21 → diode 23 → resonance inductance element 200 → node N1 → ground until time t1. When the recovery current flows in the reverse direction to the diode 23 at time t 1 and then reversely recovers, the recovery current flows back to the resonance inductance element 200 through the resonance inductance element 200 → the diode 24 → the diode 221 → the switching unit 13. . At the same time, a plasma load current flows through the path of the voltage source capacitor 12 → the switching unit 13 → the node N 1 → the load resistor 41 → the ground → the current limiting resistor 17.

  When the switching unit 13 is turned off and the switching unit 25 is turned on at time t2, a half-wave resonance current flows through the path of node N1 → resonance inductance element 200 → diode 24 → switching unit 25 → capacitor 206 → ground until time t3. When the recovery current flows in the reverse direction to the diode 24 at time t3 and then reversely recovers, the recovery current flows back to the resonance inductance element 200 through the resonance inductance element 200 → the switching unit 14 → the diode 220 → the diode 23. . At the same time, the node N1 is fixed to the ground potential through the path of the node N1, the switching unit 15, the current limiting resistor 17, and the ground. In this way, the current of the resonance inductance element 200 continues to flow and no high voltage surge occurs. Further, even when the on-operation of the switching units 13 and 15 that are turned on at times t1 and t3 is delayed due to control reasons and the path through which the resonance current flows transiently becomes an open loop, the switching unit at time t1. The energy of the high voltage surge is clamped to the voltage source capacitor 12 via the parasitic diode of the switching unit 13 at the time t3 of the 15 parasitic diodes. Therefore, no high voltage surge occurs.

  In order to avoid the high voltage surge caused by the recovery current by adding the free wheel diode as described above, a configuration in which the current limiting resistor 17 is inserted on the low voltage side as shown in FIGS. 11 and 12 is preferable. . For example, when the current limiting resistor 17 is inserted between the connection point of the two switching units 13 and 15 and the node N1, as in the configuration shown in FIGS. The current limiting resistor 17 is included in the path. That is, since a free wheel current flows through a current limiting resistor and a large power loss occurs, the use of a free wheel diode is not very appropriate in this case.

[Second Embodiment]
The apparatus of the first embodiment applies a DC pulse voltage having two voltage levels of 0 and V1 (for example, 1500V) to the capacitive load circuit 4, but does not include 0V. It is possible to change to a configuration that generates a direct current pulse voltage. FIG. 5 is a schematic configuration diagram of a DC pulse power supply device according to the second embodiment that generates a DC pulse voltage of a variable 2 voltage level.

  In this apparatus, the second DC voltage source 100 is inserted between the second switching unit 15 and the ground terminal in the basic voltage generation unit 1. For example, the voltage value V1 of the output voltage of the first DC voltage source 10 is 1500V, and the voltage value V5 of the output voltage of the second DC voltage source 100 is 400V. In this case, the voltage values V2 and V3 of the voltages applied to both ends of the series circuit in the resonance drive unit 2 are centered on {(1500-400) / 2} + 400 = 950V, V2 = 950 + Va, V3 = 950-Vb. And it is sufficient. The operation of the apparatus is the same as that of the apparatus of the first embodiment. As shown in FIG. 6, a rectangular wave DC pulse voltage having a pulse bottom voltage of 400 V and a pulse top voltage of 1500 V is applied to the capacitive load circuit 4. Can be applied.

[Third Embodiment]
The apparatus according to the first and second embodiments generates a DC pulse voltage having two voltage levels. However, the apparatus is further changed to a configuration that generates a DC pulse voltage of, for example, three voltage levels. It is also possible to do. FIG. 7 is a schematic configuration diagram of a DC pulse power supply device according to a third embodiment that generates a DC pulse voltage of a variable three voltage level.

  In this device, the basic voltage generator 1 includes two series circuits in which a switching unit and a DC voltage source are connected in series between the connection point between the first switching unit 13 and the current limiting resistor 17 and the ground terminal. Are connected in parallel. The voltage values of the output voltages of the three DC voltage sources 10, 101, 103 are all different. For example, the voltage value V1 of the output voltage of the first DC voltage source 10 is 1500V, and the voltage value V5 of the output voltage of the second DC voltage source 101 is. Is 800V, and the voltage value V6 of the output voltage of the third DC voltage source 103 is 400V. Further, as the number of voltage levels increases and the pattern of voltage change increases, two resonance current paths (a series circuit of two switching units and two diodes) in the resonance driving unit 2 are provided in parallel.

In this case, the voltage values V7, V8, V9, V10 of the voltages applied to both ends of the two series circuits in the resonance driving unit 2 are:
V7 = (1/2) (V1 + V6) + Va
V8 = V1 − {(1/2) (V1−V5) + Vb} = (1/2) (V1 + V5) −Vb
V9 = {(1/2) (V5 + V6)} + Va
V10 = V1 − {(1/2) (V5−V6) + Vb}
V7 = 950 + Va, V8 = 1150-Vb, V9 = 600 + Va, V10 = 1300-Vb.

  By extending the operation of the devices of the first and second embodiments and appropriately controlling the on / off operation of each switching unit, the voltage at the bottom of the pulse is 400 V, for example, as shown in FIG. Can be applied to the capacitive load circuit 4 with a multi-stage DC pulse voltage of 1500V and a pulse intermediate voltage of 800V. Of course, by changing the control of the on / off operation of each switching unit, the order of change of the voltage level can be changed, for example, from 400V → 800V → 1500V → 400V.

  Of course, although the control is complicated, it may be configured to generate a DC pulse voltage in which the number of voltage levels is further increased.

  It should be noted that the above-described embodiments and modifications are examples of the present invention, and it is obvious that modifications, changes, and additions as appropriate within the spirit of the present invention are included in the scope of the claims of the present application.

DESCRIPTION OF SYMBOLS 1 ... Basic voltage generation part 10, 10A, 10B, 100, 101, 103, 20, 29 ... DC voltage source 11, 14, 16, 204, 208, 22, 23, 24, 26, 28, 220, 221 ... Diode 12, 18, 27, 202, 206, 31, 33 ... capacitors 13, 15, 21, 25, 203, 207 ... switching unit 17 ... current limiting resistors 19, 200, 211, 212, 30, 32, 34 ... inductance elements 2 ... Resonant drive unit 3 ... Pulse shaping unit 4 ... Capacitive load circuit 40 ... Capacitor 41 ... Resistance 5 ... Control unit 51 ... Current detection unit

Claims (8)

A DC pulse power supply device for a plasma processing apparatus that applies a DC pulse voltage that changes to a voltage level of 2 or more to a capacitive load circuit including an electrode that forms plasma for plasma processing,
a) a pulse shaping unit in which a plurality of capacitive elements including the capacitive load circuit and a plurality of inductance elements are connected in a ladder shape;
b) a power supply unit for supplying power to the capacitive load circuit through the pulse shaping unit, including a DC voltage source that generates a first DC voltage corresponding to the highest voltage level of the DC pulse voltage; At least one of the plurality of switching units for switching the output voltage and / or the ground potential by the supply unit, the output capacitor connected between the input end and the ground end of the pulse shaping unit, and the plurality of switching units is conducted. Current path when power is supplied from the power supply unit to the capacitive load circuit, and a path through which at least one other of the plurality of switching units is conducted and current by the accumulated energy of the output capacitor flows. A basic current for inputting a voltage switched by the plurality of switching units to an input terminal of the pulse shaping unit. A generation unit,
c) A resonance inductance element having one end connected to the input end of the pulse shaping unit, a first switching unit and a second switching unit are connected in series, and between the first switching unit and the second switching unit. A series circuit portion to which the other end of the resonance inductance element is connected, and a resonance first DC that applies a second DC voltage lower than the first DC voltage to the high voltage side end of the series circuit portion. A resonance driving unit including: a voltage source; and a second DC voltage source for resonance that applies a predetermined third DC voltage lower than the second DC voltage to the low voltage side end of the series circuit unit;
d) Controlling on / off operations of the plurality of switching units of the basic voltage generation unit and the first and second switching units of the resonance driving unit, and at the time of starting up the DC pulse voltage, After turning on the first switching unit of the driving unit and increasing the voltage at the input end of the pulse shaping unit by LC resonance between the resonance inductance element and the output capacitor and / or the capacitance of the pulse shaping unit, A predetermined switching unit of the basic voltage generation unit is turned on to apply the first DC voltage from the power supply unit to the input terminal of the pulse shaping unit, and when the DC pulse voltage falls, from the basic voltage generation unit The voltage application is stopped and the second switching unit of the resonance driving unit is turned on, and the resonance inductance element, the output capacitor, and / or the pulse adjustment unit are turned on. After the voltage at the input end of the pulse shaping unit is reduced by LC resonance with the capacitance of the unit, the predetermined switching unit of the basic voltage generation unit is turned on and the potential after falling is set to the input end of the pulse shaping unit A control unit for controlling the operation of each of the switching units,
A direct-current pulse power supply for a plasma processing apparatus. A DC pulse power supply device for a plasma processing apparatus according to claim 1,
The DC current source for a plasma processing apparatus, wherein the current limiting resistor is connected between a voltage output terminal from which a voltage is output by switching the plurality of switching units and an input terminal of the pulse shaping unit. apparatus. A DC pulse power supply device for a plasma processing apparatus according to claim 1,
The current limiting resistor is connected between a low voltage side end of the low voltage side switching unit among the plurality of switching units connected in series and a ground part, and the power supply unit is connected in series. A DC pulse power supply for a plasma processing apparatus, which supplies power to both ends of a plurality of connected switching units. A DC pulse power supply device for a plasma processing apparatus according to claim 3,
In the series circuit unit, two forward connection diodes are connected in series between the first switching unit and the second switching unit, and the other end of the resonance inductance element is connected between the two diodes. And
A diode that is a forward connection is provided between the end of the current limiting resistor on the switching unit side to the connection end of the first switching unit and the diode,
A diode that is a forward connection is provided between a connection end of the second switching unit and the diode to a high voltage side end of the plurality of switching units connected in series in the basic voltage generation unit. A direct-current pulse power supply device for a plasma processing apparatus. A DC pulse power supply device for a plasma processing apparatus according to any one of claims 1 to 4,
The control unit includes a detection unit that detects a value of a current flowing through the resonance inductance element, and determines a timing for switching the switching unit in the basic voltage generation unit based on a detection result by the detection unit. DC pulse power supply for plasma processing equipment. A DC pulse power supply device for a plasma processing apparatus according to any one of claims 1 to 5,
The second DC voltage is set higher than 1/2 of the first DC voltage, and the third DC voltage is set lower than 1/2 of the first DC voltage. DC pulse power supply device. A DC pulse power supply device for a plasma processing apparatus according to claim 6,
The first DC voltage source for resonance and the second DC voltage source for resonance are respectively ½ of the first DC voltage and the second DC voltage source according to a load current flowing through a load resistor in the capacitive load circuit. A DC pulse power supply apparatus for a plasma processing apparatus, which determines a voltage difference from a DC voltage and a voltage difference between ½ of the first DC voltage and the second DC voltage. A DC pulse power supply device for a plasma processing apparatus according to claim 7,
The first DC voltage source for resonance and the second DC voltage source for resonance each include a step-up converter, a step-down converter, or a step-up / step-down converter capable of adjusting an output voltage. Power supply.

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