Pulse power supply

Abstract

The present invention provides a pulse power supply device equipped with an arbitrary waveform voltage generation unit that can obtain a negative voltage gradient without using a current source. [Solution] The pulse power supply device of the present invention generates pulses of arbitrary waveforms having multiple predetermined voltage gradients by superimposing a constant voltage DC voltage and a piecewise linear waveform voltage. The piecewise linear waveform voltage has multiple linear waveform voltages that change over time at multiple predetermined voltage change rates dV / dt from the ground potential, and these linear waveform voltages are linked together. The pulse power supply device generates this piecewise linear waveform voltage by inverter control, generates an arbitrary waveform voltage by superimposing a DC voltage and the piecewise linear waveform voltage, and generates a pulse waveform from the arbitrary waveform voltage, thereby generating pulses with arbitrary voltage gradients without using a current source.

Description

Technical Field

[0001] The present invention relates to a pulse power supply device that generates a pulse output including an arbitrary waveform in which the voltage changes at a predetermined inclination.

Background Art

[0002] The pulse output generated by the pulse power supply device is used not only for plasma processing such as film formation processing and etching processing, but can also be applied to various industrial devices not limited to plasma processing. For example, in the etching process of semiconductor devices, a negative voltage is applied to the substrate with respect to the ground in order to generate a substantially uniform negative voltage over the entire surface of the substrate when the conductor is plasma processed.

[0003] In plasma etching and deposition processes, it is known that a bias of a pulse waveform including a wide negative pulse in the etching phase and a short positive pulse in the discharge phase is used.

[0004] In the etching and deposition phases, it is known that a bias of a pulse waveform is applied to compensate for the ion deposition effect on the dielectric substrate. The pulse waveform is composed of a negative voltage gradient that decreases to compensate for the increase in the substrate potential in the etching and deposition phases, and a positive voltage pulse for attracting electrons to maintain the charge bias in the discharge phase. A configuration for generating a negative voltage gradient by incorporating ion current compensation such as a current source into a switch mode power supply is known (Patent Document 1, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] To supply an ion current that maintains the substrate voltage at a constant voltage, a predetermined negative voltage gradient must be set. In the conventional pulse power supply described above, the relationship between the negative voltage gradient and the ion current is a predetermined function, so an ion current compensation current source, such as a current source, is used to realize the negative voltage gradient.

[0007] However, current sources with high resistance suffer from the problem of poor fast response due to the large time constant of the circuit constituting the current source, which is affected by distributed capacitance. This problem of poor fast response becomes even more pronounced at high pulse frequencies.

[0008] In addition to the high-speed response challenges mentioned above, there are other points to consider regarding current sources. Generally, current sources are affected by internal resistance and temperature fluctuations, requiring temperature compensation and feedback compensation, which increases the cost of the components of the pulse power supply. As mentioned above, pulse power supplies that output high-frequency pulses using current sources have challenges related to high-speed response and cost due to the use of current sources.

[0009] The present invention aims to solve the above-mentioned conventional problems and provide a pulse power supply device equipped with an arbitrary waveform voltage generation unit that can obtain a negative voltage gradient without using a current source. [Means for solving the problem]

[0010] The pulse power supply device of the present invention generates pulses of arbitrary waveforms having multiple predetermined voltage gradients by superimposing a constant voltage DC voltage and a piecewise linear waveform voltage. The piecewise linear waveform voltage has multiple linear waveform voltages that vary over time from the ground potential at multiple predetermined voltage change rates dV / dt, which are linked together. The pulse power supply device of the present invention generates this piecewise linear waveform voltage by inverter control, generates an arbitrary waveform voltage by superimposing a DC voltage and the piecewise linear waveform voltage, and generates a pulse waveform from the arbitrary waveform voltage, thereby generating pulses with arbitrary voltage gradients without using a current source.

[0011] The pulse power supply device of the present invention comprises a first DC power supply that generates a first DC voltage, an arbitrary waveform voltage generation unit that generates a voltage of arbitrary waveform using a plurality of linear waveforms connecting two voltages, and a switch unit that generates a pulse waveform by switching between ground potential and arbitrary waveform voltage, and outputs pulses by repeating the pulse waveform at a predetermined period.

[0012] The switch unit supplies a pulsed current to the load by sequentially repeating an application phase, in which periodic pulses are applied to the load side, and a discharge phase, in which the charge accumulated on the load side is discharged, through switching operation.

[0013] The arbitrary waveform voltage generation unit generates a piecewise linear waveform voltage by linking multiple linear waveform voltages with different voltage change rates dV / dt, starting from the ground potential, using inverter control. The generated piecewise linear waveform voltage and the first voltage of the first DC power supply are then superimposed to generate an arbitrary waveform voltage.

[0014] The arbitrary waveform voltage is the output voltage of the pulse output during the pulse application phase of the switch section's pulse period. The voltage at the start of the application phase is defined as the first voltage, and the voltage at the end of the application phase is the voltage obtained by biasing the first voltage to the termination voltage of the piecewise linear waveform voltage.

[0015] The arbitrary waveform voltage generation unit comprises a second DC power supply, an inverter circuit that converts the DC voltage of the second DC power supply into an AC voltage, a rectifier circuit that converts the AC voltage of the inverter circuit into a DC voltage, and a voltage superposition circuit that superimposes the output of the first DC power supply and the output of the rectifier circuit.

[0016] In inverter circuits, in inverter control that performs DC-AC voltage conversion, (a) Time width of the application phase, (b) The point of inflection where the linear waveform voltage of the piecewise linear waveform voltage switches, and (c1) The rate of change of voltage dV / dt of each linear waveform voltage of the piecewise linear waveform voltage, or (c2) Voltage at the point of refraction By adjusting this, an arbitrary waveform voltage is generated.

[0017] By adjusting the time width (Ton) of the application phase of the output pulse period T, the time width of the pulse output is adjusted.

[0018] The inflection point is the point where a plurality of linear waveform voltages forming a broken line waveform voltage are connected, and the linear waveform voltages before and after this inflection point have different voltage change rates dV / dt. Since the adjacent linear waveforms are connected to each other at the inflection point, the inflection point can be specified by the time between the inflection points, the starting voltage of the application phase, and the voltage change rate dV / dt of each linear waveform voltage.

[0019] Also, the end voltages at the connection points of the adjacent linear waveform voltages before and after the inflection point are the same, and the inflection point can be specified by the end voltage at one end because the starting voltage of the application phase is specified.

[0020] As shown in the problem section, there is a requirement to generate a substantially uniform negative voltage over the entire surface of the substrate. However, during the application phase, the power supply output Vout or the output current Iout is not always constant and may change depending on the load state or the like. Therefore, in order to supply an ion current that maintains the substrate voltage at a constant voltage, a setting of a predetermined negative voltage gradient is required according to the power supply output Vout or the output current Iout.

[0021] In response to such a problem, the present invention forms an arbitrary waveform voltage by a broken line waveform voltage connecting a plurality of linear waveform voltages having different voltage change rates dV / dt, supplies an output to a load based on this arbitrary waveform voltage, thereby maintaining the power supply output Vout or the output current Iout at a constant value, and adding a substantially uniform negative voltage over the entire surface of the substrate.

[0022] The rectifier circuit rectifies the output of the inverter circuit to generate a stepped waveform voltage. Also, the voltage superposition circuit superimposes the first voltage of the output of the first DC power supply and the stepped waveform voltage of the output of the rectifier circuit, and generates an arbitrary waveform voltage in which a plurality of linear waveform voltages having different voltage change rates dV / dt are switched and connected at the inflection points, with the first voltage of the first DC power supply as the starting voltage.

[0023] Furthermore, it includes a control unit that controls the inverter circuit and performs inverter control based on a predetermined control value. And the control unit has a control value that determines the following values as control parameters in the inverter control. (a) The time width of the applied phase, (b) The time between the inflection points for switching the linear waveform voltages of the stepped waveform voltage, and (c1) The voltage change rate dV / dt of each linear waveform voltage, or (c2) The voltage of the inflection point

[0024] When the time change of the load can be predicted, the control parameters are assumed or measured in advance and obtained, and the control parameters or the control values based on the control parameters are stored in a storage means or the like, so that they can be read out as needed to perform inverter control. The control unit performs inverter control based on the control values for these control parameters, and generates a stepped waveform voltage formed by connecting a plurality of linear waveform voltages.

[0025] The stepped waveform voltage can be set based on the control value in a plurality of setting modes.

[0026] (Setting mode 1) At each time point when the time between the inflection points reaches the control value of the time between the inflection points, the control unit uses the control value of the voltage change rate dV / dt as the slope of the linear waveform voltage, and sequentially switches the linear waveform voltages of the stepped waveform voltage to generate the stepped waveform voltage.

[0027] (Setting mode 2) The control unit, at each point in time when the time between refraction points reaches the control value for the time between refraction points, uses the slope determined based on the control value of the voltage at the refraction point at that point and the next point in time, and the control value for the time between refraction points, as the slope of the linear waveform voltage, and sequentially switches the linear waveform voltage of the piecewise linear waveform voltage to generate a piecewise linear waveform voltage.

[0028] (Setting Method 3) The control unit determines voltage fluctuations at each point in time when the time between refraction points reaches the control value of the time between refraction points by comparing the control value of the voltage at the refraction point at that point with the detected value of the output voltage at that point. When a voltage fluctuation is determined, the control unit sets the slope determined based on the detected value of the output voltage at that point and the control value of the voltage at the next refraction point as the slope of the linear waveform voltage, and sequentially switches the linear waveform voltage of the piecewise linear waveform voltage to generate the piecewise linear waveform voltage.

[0029] The voltage superposition circuit generates an arbitrary waveform voltage by superimposing the piecewise linear waveform voltage rectified by the rectifier circuit with the first voltage of the first DC power supply.

[0030] The piecewise linear waveform voltage output from the rectifier circuit exhibits a voltage waveform consisting of multiple linear waveform voltages whose voltage changes linearly over time, but the voltage at the starting point of the application phase is the ground potential, and the voltage changes over time from the ground potential. The arbitrary waveform voltage is formed by superimposing a first voltage onto the piecewise linear waveform voltage, resulting in a linear waveform voltage that changes linearly over time with a predetermined voltage change rate dV / dt starting from the first voltage as the starting voltage, and another linear waveform voltage with a different voltage change rate dV / dt that is switched at the inflection point. By controlling the voltage change rate dV / dt of each connected linear waveform voltage in response to changes in the power supply output Vout or output current Iout due to fluctuations in load conditions, the power supply output Vout or output current Iout is kept constant, and an ion current is supplied to maintain the substrate voltage at a constant voltage.

[0031] The switch unit synchronizes the start of pulse generation in the switch unit with the start of output in the arbitrary waveform voltage generation unit, and generates a pulse waveform by switching between the ground potential of 0V and the arbitrary waveform voltage generated by the arbitrary waveform voltage generation unit. The generated pulse waveform has a first section where the potential is the ground potential, and a second section of a piecewise linear waveform voltage formed by linking a plurality of linear waveform voltages that change linearly over time at a predetermined voltage change rate dV / dt from the first voltage. The 0V in the first section and the first voltage at the starting point of the second section have a potential difference equal to the first voltage.

[0032] The starting voltage of the arbitrary waveform voltage is determined by the first voltage of the first DC power supply, and the ending voltage of the arbitrary waveform voltage is determined by the voltage change rate dV / dt of the piecewise linear waveform voltage and the time width of the second section of the piecewise linear waveform voltage.

[0033] The switch unit generates a pulse waveform from an arbitrary waveform voltage, defines it as one pulse, and outputs a periodic pulse by repeating this pulse waveform at a predetermined period. The time width of one pulse is the sum of the time widths of the first section and the second section, and is determined according to the pulse period.

[0034] In the case of a negative polarity arbitrary waveform voltage, the switch unit outputs a periodic pulse in which one pulse consists of a voltage waveform comprising two voltage sections: a first section of 0V and a second section of an arbitrary waveform voltage that changes over time from a negative first voltage to a piecewise linear waveform voltage.

[0035] In the arbitrary waveform voltage generation unit of the present invention, the arrangement position of the voltage superposition circuit can be configured in multiple forms.

[0036] (First form): The first form of the voltage superposition circuit is placed in a rectifier circuit. For example, one configuration is in which the output terminal of the first DC power supply is connected to one output terminal of the rectifier circuit.

[0037] (Second form): A transformer is provided between the second form of inverter circuit and rectifier circuit, the voltage superposition circuit is located on this transformer, and the output terminal of the first DC power supply is connected to one end of the secondary side of the transformer. [Effects of the Invention]

[0038] As described above, the pulse power supply device of the present invention provides a variable waveform voltage generation unit that can obtain a predetermined voltage gradient without using a current source, thereby enabling high-speed response. [Brief explanation of the drawing]

[0039] [Figure 1] This is a diagram illustrating the schematic configuration of the pulse power supply device of the present invention. [Figure 2] This is a timing chart illustrating an example of operation of the pulse power supply device of the present invention. [Figure 3A] This is a diagram illustrating an example of a piecewise linear voltage waveform. [Figure 3B] This is a diagram illustrating an example of a piecewise linear voltage waveform. [Figure 4] This is a flowchart illustrating example 1 of setting the piecewise linear waveform voltage. [Figure 5] This is a flowchart illustrating example 2 of setting the piecewise linear waveform voltage. [Figure 6A] This figure illustrates an example of the operation of the discharge phase of the pulse power supply device of the present invention. [Figure 6B] This figure illustrates an example of the operation of the discharge phase of the pulse power supply device of the present invention. [Figure 7A] This figure illustrates an example of operation during the application phase of the pulse power supply device of the present invention. [Figure 7B] This figure illustrates an example of operation during the application phase of the pulse power supply device of the present invention. [Figure 8] This is a schematic diagram of a first configuration example of the arbitrary waveform voltage generation unit of the present invention. [Figure 9] This is a timing chart of a first configuration example of the arbitrary waveform voltage generation unit of the present invention. [Figure 10] This is a schematic diagram of a second example configuration of the arbitrary waveform voltage generation unit of the present invention. [Figure 11]This is a timing chart of a second configuration example of the arbitrary waveform voltage generation unit of the present invention. [Figure 12A] This figure illustrates an example configuration of the voltage superposition circuit of the present invention. [Figure 12B] This figure illustrates an example configuration of the voltage superposition circuit of the present invention. [Figure 13] This is a diagram illustrating the smoothing circuit of the present invention. [Figure 14] This is a diagram illustrating a first embodiment of the present invention, which includes a smoothing circuit. [Figure 15] This is a diagram illustrating a second embodiment of the present invention, which includes a smoothing circuit. [Figure 16A] This figure shows an example of a waveform in the smoothing circuit of the present invention. [Figure 16B] This figure shows an example of a waveform in the smoothing circuit of the present invention. [Figure 17] This figure illustrates an example of a plasma load as the load of the pulse power supply device of the present invention. [Figure 18] This figure shows an example of a switch drive signal, power supply output Vout, and output current Iout. [Figure 19] This figure shows the wafer voltage Vsh, power supply output Vout, and ion current Ip. [Modes for carrying out the invention]

[0040] (1) Schematic configuration and operation example of the pulse power supply device of the present invention The following describes the schematic configuration and operation examples of the pulse power supply device of the present invention with reference to Figures 1 to 6.

[0041] The pulse power supply unit 1 comprises a power supply unit 10, a switch unit 13, and a control unit 15. The power supply unit 10 includes a first DC power supply 11 that generates a first voltage of a constant voltage as the first power supply, and an arbitrary waveform voltage generation unit 12 that generates an arbitrary waveform voltage as the second power supply.

[0042] The arbitrary waveform voltage generation unit 12 generates a piecewise linear waveform voltage Vline, which is formed by linking together a plurality of linear waveform voltages whose voltage changes at a predetermined voltage change rate dV / dt, starting from the ground potential. By superimposing the first voltage of the first DC power supply 11 onto this piecewise linear waveform voltage Vline, it generates an arbitrary waveform voltage whose voltage changes at a predetermined voltage change rate dV / dt, starting from the first voltage, and outputs a pulse of the arbitrary waveform voltage output Vopt.

[0043] The switch unit 13 supplies current to the load by sequentially repeating a discharge phase, in which it discharges the charge accumulated on the load side through switching operation, and an application phase, in which it applies periodic pulses to the load side. The switch unit 13 includes a pulse switch unit 13a for outputting pulses of an arbitrary waveform voltage output Vopt to the load during the application phase, and a discharge circuit 13b for discharging the charge accumulated on the load. The switching operation of the pulse switch unit 13a and the discharge circuit 13b is controlled by the control unit 15.

[0044] During the application phase, the switch unit 13 applies the arbitrary waveform voltage generated by the arbitrary waveform voltage generation unit 12 to the load as a single pulse waveform of a periodic pulse. During the discharge phase, the charge accumulated on the load side is discharged and the output of the switch unit 13 becomes 0V. Therefore, the output of the switch unit 13 at the start of the application phase changes from 0V to the first voltage. The pulse output from the switch unit 13 is supplied to the load 21 as a power supply output.

[0045] The pulse power supply unit 1 may be configured to include a smoothing circuit. The smoothing circuit can take two forms: a first form in which the smoothing circuit is connected to the output terminal of the arbitrary waveform voltage generator 12, and a second form in which the smoothing circuit is connected to the output terminal of the pulse switch section 13a of the switch section 13. The smoothing circuit in the first form suppresses noise contained in the output of the arbitrary waveform voltage generator. The smoothing circuit in the second form suppresses voltage oscillations such as overshoot and undershoot that occur in the switch section 13 due to voltage changes between the discharge phase and the application phase. Note that the smoothing circuit is not shown in Figure 1.

[0046] The control unit 15 controls the arbitrary waveform voltage generation unit 12 and the switch unit 13. In this process, the output control of the arbitrary waveform voltage output Vopt of the arbitrary waveform voltage generation unit 12 and the pulse control of the switch unit 13 are performed synchronously.

[0047] Figure 2 is a timing chart illustrating an example of operation of the pulse power supply device of the present invention. The power supply unit 10 comprises a first power supply, a first DC power supply 11, and a second power supply, an arbitrary waveform voltage generation unit 12. The first DC power supply 11 of the first power supply outputs a first voltage V1 of constant voltage. The arbitrary waveform voltage generation unit 12 of the second power supply generates a piecewise linear waveform voltage Vline whose voltage changes at a predetermined voltage change rate dV / dt, starting from the ground potential, and generates a trapezoidal waveform voltage by superimposing the first voltage V1 on this piecewise linear waveform voltage Vline.

[0048] The arbitrary waveform voltage generation unit 12 generates a piecewise linear waveform voltage Vline based on a control signal from the control unit 15, superimposes the generated piecewise linear waveform voltage Vline with the first voltage V1 to generate an arbitrary waveform voltage, and outputs it as the arbitrary waveform voltage output Vopt.

[0049] The control signal of the arbitrary waveform voltage generation unit 12 has the same output pulse period T as the switch control signal that controls the switch unit 13, and is synchronized with the switch control signal. The generation of the piecewise linear waveform voltage Vline by the control signal of the arbitrary waveform voltage generation unit 12 and the start of the pulse application phase by the switch control signal are simultaneous point A. Also, the end of the piecewise linear waveform voltage Vline by the control signal of the arbitrary waveform voltage generation unit 12 and the end of the pulse application phase and the start of the discharge phase by the switch control signal are simultaneous point B.

[0050] Here, when the duty cycle with respect to the output pulse period T (=Ton + Toff) is Ton / T, the on time and application phase time of the control signal of the arbitrary waveform voltage generation unit 12 are the same Ton, and the off time and discharge phase time of the control signal of the arbitrary waveform voltage generation unit 12 are the same Toff.

[0051] The piecewise linear waveform voltage Vline changes from 0V at the start of the application phase at a predetermined rate of change dV / dt for each of the multiple linear waveform voltages, and at the end of the application phase, it becomes a voltage ΔV determined by the product of the rate of change dV / dt and Ton (Ton × dV / dt). The arbitrary waveform voltage output Vopt changes from the first voltage V1 at the start of the application phase at a predetermined rate of change dV / dt, and at the end of the application phase, it becomes a voltage (V1 + ΔV) obtained by superimposing the voltage ΔV on the first voltage V1.

[0052] Voltage ΔV and voltage (V1+ΔV) depend on the voltage rate of change dV / dt, Ton, or the duty cycle of the periodic pulse, because ΔV is the product of the voltage rate of change dV / dt and Ton (Ton × dV / dt). Therefore, if the voltage rate of change dV / dt, Ton, or the duty cycle of the periodic pulse is changed, voltages ΔV and (V1+ΔV) will have different values.

[0053] The first type of smoothing circuit suppresses noise components included in the arbitrary waveform voltage output Vopt, and the second type of smoothing circuit suppresses voltage oscillations of overshoot and undershoot included in the switch output of the switch unit 13. The power output of the pulse power supply unit 1 is supplied to the load 21.

[0054] Figure 2A shows the voltage V1 of the first DC power supply 11, Figure 2B shows the control signal for controlling the inverter of the arbitrary waveform voltage generation unit 12, Figure 2C shows the piecewise waveform voltage Vline, Figure 2D shows the arbitrary waveform voltage output Vopt, Figure 2E shows the control signal SWA for controlling the pulse switch unit of the switch unit 13, Figure 2F shows the output Vsw of the switch unit 13, and Figure 2G shows the power supply output Vout.

[0055] The piecewise linear voltage Vline in Figure 2C is formed at Ton in the output pulse period T shown in Figure 2B based on the inverter control signal, but is not formed at Toff in the output pulse period T. The arbitrary waveform voltage output Vopt shown in Figure 2D is formed by superimposing the voltage V1 of the first DC power supply 11 shown in Figure 2A and the piecewise linear voltage Vline shown in Figure 2C.

[0056] The piecewise linear voltage Vline shown in Figure 2C and the arbitrary waveform voltage output Vopt shown in Figure 2D have a starting point P0, inflection point P1, inflection point P2, and ending point P3, and multiple linear waveform voltages connecting these inflection points. In the figures, a total of four inflection points are shown, including the starting point P0 and the ending point P3, but the number of inflection points can be any number of points, at least three, including the starting point, intermediate point, and ending point.

[0057] Due to the superposition of voltage V1 and the piecewise linear waveform voltage Vline, the voltage at the starting point P0 of the arbitrary waveform voltage output Vopt becomes V1, and the voltage at the ending point P3 becomes V3. The voltage V3 at the ending point P3 is a voltage corresponding to the voltage changes of multiple linear waveform voltages, and the voltage difference ΔV between the starting point and ending point of the piecewise linear waveform voltage Vline is (V1-V3).

[0058] The control signal for switch SWA in Figure 2E is synchronized with the control signal for the inverter in Figure 2B. Control signal SWA controls the on / off state of the pulse switch section 13a, and the control signal for switch SWB controls the on / off state of the discharge circuit 13b.

[0059] In Figure 2F, the sections labeled Ph_dis represent the discharge phase, and the sections labeled Ph_app represent the application phase. In the discharge phase, the switch SWA of the pulse switch unit 13a is in the off state, and the switch SWB of the discharge circuit 13b is in the on state. On the other hand, in the application phase, the switch SWA of the pulse switch unit 13a is in the on state, and the switch SWB of the discharge circuit 13b is in the off state.

[0060] The switch SWA of the pulse switch section 13a switches from the off state to the on state, thereby switching from the discharge phase to the application phase, and outputs an arbitrary waveform voltage output Vopt as a pulse output during the Ton of the application phase.

[0061] Switch SWB of the discharge circuit 13b switches from the off state to the on state, thereby switching from the application phase to the discharge phase. During the Toff period of the discharge phase, the charge accumulated on the load is discharged to ground, and the voltage of the arbitrary waveform voltage output Vopt is set to 0V.

[0062] Figures 2F and 2G both show output waveforms, but Figure 2F shows the output waveform of the pulse switch section, while Figure 2G shows the output waveform of the power supply after the output of the pulse switch section has been smoothed.

[0063] (Example of a piecewise linear voltage waveform) Examples of piecewise linear voltage waveforms are explained using Figures 3A and 3B. Here, we show an example of a piecewise linear voltage waveform with two inflection points P1 and P2 between the starting point P0 and the ending point P3, but the number of inflection points can be any number. In Figures 3A and 3B, the linear voltage waveform shown by the dashed line represents a waveform where the starting point P0 and the ending point P3 are connected by a single straight line.

[0064] In the example of a piecewise linear voltage waveform shown in Figure 3A, the voltage V1 at the inflection point P1 is lower and the voltage V2 at the inflection point P2 is higher compared to the linear voltage waveform shown by the dashed line. In this example, the rate of change dV / dt of the linear voltage waveform connecting the starting point P0 and the inflection point P1 is expressed as V1 / T1, the rate of change dV / dt of the linear voltage waveform connecting the inflection point P1 and the inflection point P2 is expressed as (V2-V1) / T2, and the rate of change dV / dt of the linear voltage waveform connecting the inflection point P2 and the end point P3 is expressed as (V3-V2) / T3. Note that T1 is the time interval between the starting point P0 and the inflection point P1, T2 is the time interval between the inflection point P1 and the inflection point P2, and T3 is the time interval between the inflection point P2 and the end point P3.

[0065] In the example of a piecewise linear voltage waveform shown in Figure 3B, the voltage V1 at the inflection point P1 is higher and the voltage V2 at the inflection point P2 is lower compared to the linear voltage waveform shown by the dashed line. In this example waveform as well, the rate of change dV / dt of the linear voltage waveform connecting the starting point P0 and the inflection point P1 is expressed as V1 / T1, the rate of change dV / dt of the linear voltage waveform connecting the inflection point P1 and the inflection point P2 is expressed as (V2-V1) / T2, and the rate of change dV / dt of the linear voltage waveform connecting the inflection point P2 and the ending point P3 is expressed as (V3-V2) / T2.

[0066] (Setting methods for piecewise linear waveform voltage) The setting method of the piecewise linear waveform voltage by the control unit will be explained with reference to Figures 4 and 5. In the following, we will describe a case where, in the pulse period for generating one pulse, an application phase is performed by switching operation to apply a periodic pulse to the load side, and a discharge phase is performed to discharge the charge accumulated on the load side, and the current generated by repeating this pulse period is supplied to the load.

[0067] When the control unit generates a piecewise linear waveform voltage in inverter control, it sets the following control values ​​as control parameters. (a) Time width T of the applied phase, (b) The time Tk between the inflection points that switch the piecewise linear voltage to the linear voltage, and (c1) The rate of change of voltage dV / dt for each linear waveform voltage, or (c2) Voltage at the point of refraction

[0068] (Setting Mode 1) Setting method 1 for the piecewise linear waveform voltage will be explained using Figure 4. In this setting example 1, when the time width T of the application phase and the time Tk between inflection points are set and the inflection points are determined, an example is shown in which the voltage change rate dV / dt of each linear waveform voltage constituting the piecewise linear waveform voltage is set. In the flowchart of Figure 4, the steps are indicated by symbols S1 to S7.

[0069] The time width T of the applied phase and the time Tk between the refraction points are predetermined and stored as control values ​​for determining the refraction points, and the voltage change rate dV / dt of the linear waveform voltage is predetermined and stored as a control value for determining the slope of the linear waveform between the refraction points. These control values ​​can be stored in any memory device in a readable format.

[0070] First, the voltage change rate dV / dt of the linear waveform voltage at the beginning of the application phase, which was set as an initial value, is read (S1), the voltage change rate dV / dt of the initial linear waveform voltage is set, and a linear waveform voltage is generated using this voltage change rate dV / dt (S2).

[0071] Subsequently, based on whether the elapsed time since the start of outputting the linear waveform voltage has reached the time Tk between the inflection points, it is determined whether or not an inflection point has been reached (S3). If an inflection point has been reached, the voltage change rate dV / dt of the next linear waveform voltage is read out (S4), and the voltage change rate dV / dt of the read linear waveform voltage is changed (S5).

[0072] It is determined whether the refraction point is the endpoint of the piecewise linear voltage. If it is not the endpoint, steps S3 to S5 are repeated (S6). If the refraction point is the endpoint in S6, one application phase is completed, and after the pulse period formed by the discharge phase is completed, steps S1 to S6 are repeated in the next pulse period (S7).

[0073] (Setting Mode 2) The setting method 1 described above is an example that uses a pre-set rate of change dV / dt of linear waveform voltage. However, in setting method 2, the piecewise linear waveform voltage may be set using the voltage at the inflection point instead of the rate of change dV / dt. In this case, the rate of change dV / dt of the first linear waveform voltage is obtained by dividing the voltage difference (V1-V0) between the voltage V0 at the starting point P0 of the piecewise linear waveform voltage and the voltage V1 at the inflection point P1 by the time width T1. The rate of change dV / dt of the next linear waveform voltage is obtained by dividing the voltage difference (V2-V1) between the voltage V1 at the inflection point P1 and the voltage V2 at the inflection point P2 by the time width T2. The same method can be used to obtain the linear waveform voltages for other sections.

[0074] (Setting Method 3) Setting method 3 for piecewise linear waveform voltage will be explained using Figure 5. In this setting example 2, the time width T of the application phase and the time Tk between inflection points are set from the control values ​​described above, determining the inflection points and the output voltage Vk at each inflection point, and this example shows how to set the voltage change rate dV / dt of each linear waveform voltage. In the flowchart of Figure 5, the steps are indicated by symbols S11 to S21.

[0075] First, the rate of change dV / dt of the linear waveform voltage at the beginning of the application phase is calculated. This rate of change dV / dt is calculated by dividing the voltage difference (V1-V0) between the voltage V0 at the starting point P0 and the voltage V1 at the first inflection point P1 by the time width T1 (S11). The calculated rate of change dV / dt is set as the initial value (S12).

[0076] At the inflection point Pk after the time width of the linear waveform voltage has elapsed (S13), the output voltage Vk set at the inflection point Pk is read out (S14), and the output voltage Vo at that time is detected (S15). The detected output voltage Vo and the read output voltage Vk are compared, and the detected output voltage Vo is set to the set output voltage V k It is determined whether or not it is fluctuating. In the determination, for example, the output voltage Vo and the output voltage V k This can be done based on whether the difference exceeds a pre-set threshold. If it is determined that there is no voltage fluctuation, steps S13 to S15 are repeated (S16).

[0077] If a voltage fluctuation is detected, the voltage Vk+1 at the next inflection point Pk+1 is read (S17), and the voltage change rate dV / dt is calculated by dividing the voltage difference (Vk+1-Vo) between the output voltage Vo and the read voltage Vk+1 at inflection point Pk+1 by the time width T1 ((Vk+1)-Vo) / T1 (S18), and the voltage change rate dV / dt is updated (S19). Then, steps S13 to S19 are repeated until the end of the piecewise linear voltage (S20), and after one application phase is completed and the pulse period for forming one pulse via the discharge phase is completed, steps S11 to S20 are repeated in the next pulse period (S21).

[0078] (Example of operation during the discharge phase) Figure 6 is a diagram illustrating an example of the discharge phase operation. Figures 6A and 6B show the operating state in the discharge phase Ph_dis in Figure 2F when the power supply output Vout rises from V2 to 0V, and the operating state when the power supply output Vout becomes 0V, respectively.

[0079] In Figure 6A, the discharge phase Ph_dis1 is the point when the switch SWA of the pulse switch unit 13a switches to the OFF state and the SWB of the discharge circuit 13b switches to the ON state. This point corresponds to the section represented as Dis1 in Figure 2F. In this Dis1, the power supply output Vout rises from V2 to 0V, and the output current Iout decreases from a steep discharge current toward 0A. The current Ir in the applied phase corresponds to the ion current Ip in the case of a plasma load.

[0080] In the discharge phase Ph_dis2 shown in Figure 6B, the switch SWA of the pulse switch section 13a is in the off state, and the SWB of the discharge circuit 13b is in the on state. This state corresponds to the section represented as Dis2 in Figure 2. In this Dis2 phase, the power supply output Vout is 0V, and the output current Iout is 0A.

[0081] (Example of operation during the induction phase) Figure 7 is a diagram illustrating an example of operation during the application phase. Figures 7A and 7B show the operating state at the point when the power supply output Vout falls from 0V to V1 and the operating state when the power supply output Vout changes from V1 to V2, respectively, during the application phase Ph_app in Figure 2F.

[0082] The application phase Ph_app1 in Figure 7A is the point in time when the switch SWA of the pulse switch section 13a switches to the ON state and the SWB of the discharge circuit 13b switches to the OFF state. This point in time corresponds to the point in time represented as App1 in Figure 2F. At this point in time App1, the power supply output Vout falls from 0V to V1, and current Iq flows toward the load. The voltage change at the point in time App1 is determined by the time constant of the circuit connected downstream of the switch section.

[0083] In Figure 7B, the application phase Ph_app2 is when the switch SWA of the pulse switch unit 13a is ON and the SWB of the discharge circuit 13b is OFF. This state corresponds to the section represented as App2 in Figure 2F. During App2, the power supply output Vout changes from V1 at a voltage change rate dV / dt, and at the end of App2, the power supply output Vout becomes V2. In the case of a plasma load, a constant current Ir flows in the output current Iout, which corresponds to the ion current Ip determined based on the voltage change rate dV / dt. An example of currents Ir and Iq is shown in Figure 18.

[0084] (2) Arbitrary waveform voltage generation unit The arbitrary waveform voltage generation unit 12 of the present invention comprises an inverter circuit that converts a DC voltage to an AC voltage, a rectifier circuit that converts the AC voltage of the inverter circuit to a DC voltage, and a voltage superposition circuit that superimposes the output of the DC power supply of the first power supply and a piecewise linear waveform voltage Vline output via the rectifier circuit to generate a trapezoidal waveform voltage and outputs it as an arbitrary waveform voltage output Vopt.

[0085] The arbitrary waveform voltage generation unit of the present invention can be configured in multiple forms, in which a voltage superposition circuit that superimposes the output of a DC power supply and a piecewise linear waveform voltage Vline is arranged at different positions within the circuit of the arbitrary waveform voltage generation unit.

[0086] The first and second configuration examples of the arbitrary waveform voltage generation unit of the present invention will be described below with reference to Figures 8 to 11. Figures 8 and 9 are diagrams illustrating the first configuration example of the arbitrary waveform voltage generation unit, and Figures 10 and 11 are diagrams illustrating the second configuration example of the arbitrary waveform voltage generation unit. Figure 12 is a diagram illustrating an example of the voltage superposition circuit configuration.

[0087] (a) First configuration example of the arbitrary waveform voltage generation unit Figure 8 shows a schematic configuration of a first example of the arbitrary waveform voltage generation unit of the present invention, and Figure 9 shows a timing chart of the first example of the arbitrary waveform voltage generation unit of the present invention.

[0088] The arbitrary waveform voltage generation unit 12A of the first configuration example comprises a second DC power supply 12a, an inverter circuit 12b, a transformer 12c, and a rectifier circuit 12d, and the voltage superposition circuit 12e is provided within the rectifier circuit 12d.

[0089] The second DC power supply 12a may use an AC / DC power supply that converts AC to DC and outputs a DC voltage, or it may use a regular DC power supply. The source of AC (alternating current) may be either an external power supply or an internal power supply. The inverter circuit 12b converts the input DC voltage into an AC voltage and adjusts the voltage value of the converted AC voltage before outputting it. The transformer 12c converts the amplitude of the AC voltage from the inverter circuit 12b based on a transformation ratio determined by a predetermined winding ratio. The rectifier circuit 12d rectifies the AC voltage from the transformer 12c and converts it into a DC voltage.

[0090] The inverter circuit 12b is inverter-controlled based on control commands output from the control unit 15. The control commands of the control unit 15 may be generated based on feedback signals of voltage and / or current from the output of the arbitrary waveform voltage generator, or they may be generated based on external signals from external devices (not shown).

[0091] The inverter circuit 12b is driven at a high frequency of, for example, several hundred kHz to several tens of MHz. The inverter circuit 12b may be a single-transistor flyback inverter using one switching element, a two-transistor half-bridge inverter using two switching elements, or a four-transistor full-bridge inverter using four switching elements.

[0092] The voltage superposition circuit 12e is incorporated into the rectifier circuit 12d and superimposes the first voltage V1 of the first DC power supply 11 onto the rectified output of the rectifier circuit 12d. Figure 12A shows an example configuration of the voltage superposition circuit 12e incorporated into the rectifier circuit 12d. Here, the rectifier circuit 12d is shown as an example circuit consisting of a diode bridge. In the circuit configuration example in Figure 12A, the output terminal of the voltage superposition circuit 12e is connected to one output terminal of the rectifier circuit 12d, and the rectified output with the first voltage V1 superimposed is output as an arbitrary waveform voltage output.

[0093] Figure 9 shows the case where PWM control is used as the inverter control. Inverter control is performed during the on time Ton, which is based on the duty cycle, within the output pulse period T, and is resumed after the off time Toff has elapsed. PWM control controls the pulse width every inverter period Tinv (=1 / f_inv), which is determined by the drive frequency f_inv. The output voltage is adjusted by gradually increasing or decreasing the pulse width to raise or lower the peak value of the output voltage.

[0094] When generating the gradient waveforms of the piecewise linear voltage Vline and the arbitrary waveform voltage output Vopt using inverter control, the drive frequency f_inv of the PWM control used for inverter control must be higher than the output pulse frequency f_pulse, and it is desirable that it be at least 5 times higher, taking into account the responsiveness when a smoothing circuit is connected after the arbitrary waveform voltage generation unit 12.

[0095] The transformer 12c adjusts the peak value of the inverter output of the inverter circuit 12b based on the transformation ratio determined by the winding ratio and outputs it to the rectifier circuit 12d. The rectifier circuit 12d rectifies the inverter output and outputs a piecewise linear waveform voltage that changes voltage at a predetermined voltage change rate dV / dt. The piecewise linear waveform voltage is output during the on time Ton and not during the off time Toff. The voltage superposition circuit 12e generates a superimposed output by superimposing a first voltage V1 on the rectified output of the rectifier circuit 12d.

[0096] (b) Second example of configuration of the arbitrary waveform voltage generation unit Figure 10 shows a schematic configuration of a second example of the arbitrary waveform voltage generation unit of the present invention, and Figure 11 shows a timing chart of the second example of the arbitrary waveform voltage generation unit of the present invention.

[0097] The arbitrary waveform voltage generation unit 12B of the second configuration example comprises a second DC power supply 12a, an inverter circuit 12b, a transformer 12c, and a rectifier circuit 12d, with a voltage superposition circuit 12e provided within the transformer 12c.

[0098] The arbitrary waveform voltage generator 12B in the second configuration example, like the arbitrary waveform voltage generator 12A in the first configuration example, includes a second DC power supply 12a, an inverter circuit 12b, a transformer 12c, and a rectifier circuit 12d, but differs in that the voltage superposition circuit 12e is incorporated into the transformer 12c. Here, we will omit the explanation of the second DC power supply 12a, the inverter circuit 12b, the transformer 12c, and the rectifier circuit 12d, and only explain the voltage superposition circuit 12e.

[0099] The voltage superposition circuit 12e is configured to be incorporated within the transformer 12c, and superimposes the first voltage V1 of the first DC power supply 11 onto the inverter output of the inverter circuit 12b. Figure 12B shows an example of the configuration of the voltage superposition circuit 12e.

[0100] In the circuit configuration example shown in Figure 12B, the first DC power supply 11 is connected to one of the output terminals of the secondary side of the transformer 12c, thereby superimposing the first voltage V1 onto the inverter output that has been voltage-converted by the transformer 12c.

[0101] Figure 11, similar to Figure 9, shows the case where PWM control is used as the inverter control. Inverter control is performed within the output pulse period T during an on-time Ton based on the duty cycle, and resumes after the off-time Toff has elapsed. PWM control controls the pulse width for each inverter period Tinv, which is determined by the drive frequency f_inv. The output voltage is adjusted by gradually increasing or decreasing the pulse width to raise or lower the peak value of the output voltage.

[0102] Similar to the first configuration example, when generating the gradient waveforms of the piecewise linear voltage Vline and the arbitrary waveform voltage output Vopt by inverter control, the drive frequency f_inv of the PWM control that performs inverter control must be higher than the output pulse frequency f_pulse, and it is desirable that it be five times or more higher, taking into account the responsiveness when a smoothing circuit is connected after the arbitrary waveform voltage generation unit 12.

[0103] Transformer 12c adjusts the peak value of the inverter output of inverter circuit 12b based on the transformation ratio.

[0104] The voltage superposition circuit 12e superimposes a first voltage V1 onto the inverter output, which has been voltage-converted by the transformer 12c, to generate a transformer output, which is then output to the rectifier circuit 12d. The rectifier circuit 12d rectifies the inverter output and outputs a piecewise linear waveform voltage that changes voltage at a predetermined voltage change rate dV / dt. The piecewise linear waveform voltage is output during the on-time Ton and not during the off-time Toff.

[0105] (3) Smoothing circuit Figure 13 shows an example of the configuration of the smoothing circuit 14. The smoothing circuit 14 consists of an LC circuit with a series-connected inductor Lp and a parallel-connected capacitor Cp. Note that this smoothing circuit 14 is just one example and is not limited to this LC circuit.

[0106] The smoothing circuit of the pulse power supply device 1 of the present invention can be configured in a first form in which the smoothing circuit is connected to the output terminal of the arbitrary waveform voltage generation unit 12, and a second form in which the smoothing circuit is connected to the output terminal of the pulse switch unit 13a of the switch unit 13. The smoothing circuit in the first form suppresses noise components included in the arbitrary waveform voltage output. The smoothing circuit in the second form suppresses voltage oscillations of overshoot and undershoot that occur in the switch unit 13 due to voltage changes between the discharge phase and the application phase.

[0107] (a) First example of a smoothing circuit The first form of the smoothing circuit 14A will be explained with reference to Figure 14. Figure 14 shows an example configuration of the arbitrary waveform voltage generation unit 12A that performs voltage superposition in the rectifier circuit 12d.

[0108] The smoothing circuit 14A is connected between the output terminal of the rectifier circuit 12d of the arbitrary waveform voltage generation unit 12A and the input terminal of the switch unit 13, and suppresses high-frequency noise components included in the arbitrary waveform voltage output generated by the rectifier circuit, etc. In this circuit configuration, even if the switch SWA of the pulse switch unit 13a in the switch unit 13 is switched to the off state, the voltage charged in the capacitor in the smoothing circuit 14A does not drop to the voltage of the V1 power supply. Therefore, in the first form, a discharge circuit 17 is connected to discharge the voltage charged in the capacitor in the smoothing circuit 14A.

[0109] (b) A second example of a smoothing circuit The second form of the smoothing circuit 14B will be explained using Figures 15 and 16. Figure 15 shows an example configuration of the arbitrary waveform voltage generation unit 12A that performs voltage superposition in the rectifier circuit 12d, and Figure 16 shows an example waveform of the smoothing circuit 14B.

[0110] In the second embodiment, the smoothing circuit 14B is connected between the pulse switch section 13a and the discharge circuit 13b in the switch section 13. Due to the switching operation performed by the pulse switch section 13a of the switch section 13, the voltage switches abruptly from V2 to the first voltage V1 during discharge, and also abruptly from the ground potential of 0V to the first voltage V1. This voltage change causes overshoot or undershoot in the output waveform.

[0111] When the switch SWA of the pulse switch unit 13a is ON, the capacitor of the smoothing circuit 14B is charged. Subsequently, when the switch SWA of the pulse switch unit 13a is switched OFF, the voltage charged in the capacitor of the smoothing circuit 14B is discharged because the discharge circuit 13b is turned ON. As a result, voltage oscillations such as overshoot and undershoot caused by voltage changes during the switching between the ON and OFF states of the pulse switch unit 13a between the discharge phase and the application phase are suppressed, the voltage value of the power supply output is set to a predetermined time constant, and a power supply output Vout with suppressed fluctuations is output.

[0112] Figure 16 shows an example waveform of the smoothing circuit 14B. Figure 16A shows the case where the constants of inductor Lf and capacitor Cf are small, and Figure 16B shows the case where the constants of inductor Lf and capacitor Cf are large.

[0113] By selecting small values ​​for the inductor Lf and capacitor Cf, the time constant of the LC circuit can be set to a small value, thereby shortening the voltage rise time. If the time constant of the LC circuit is large, the voltage rise time t2 becomes long, requiring a longer discharge time, which affects the setting of the high-frequency output pulse frequency f_pulse. It is desirable that the voltage rise time t1 be shorter than, for example, 10% of the pulse period.

[0114] (4) Examples of plasma loads Using Figure 17, an example of a plasma load in the pulse power supply device of the present invention will be explained. When the load is a plasma load, the plasma load in the plasma chamber 2 is represented by capacitors Cw, Cp, and ion current Ip. Capacitor Cw is the intrinsic capacitance of the components of the plasma chamber, such as the substrate, and Cp is the indeterminate capacitance of the sheath capacitance and stray capacitance.

[0115] In plasma chamber 2, the ion current Ip supplied to the substrate placed inside the chamber is kept constant, thereby maintaining the wafer voltage Vsh of the substrate at a constant voltage.

[0116] The pulse power supply device of the present invention supplies a constant ion current Ip as described above, and supplies power to the load of the plasma chamber 2 to maintain the wafer voltage Vsh of the substrate at a constant voltage.

[0117] The pulse power supply device of the present invention feeds back the power output Vout and / or output current Iout detected by the detector 16 to the control unit 15, generates a control value that makes the power output Vout or output current Iout a constant value, and controls the switch SWA of the pulse switch unit 13a and the switch SWB of the discharge circuit 13b.

[0118] Figure 18 schematically shows an example of a drive signal, power supply output Vout, and output current Iout that drives a switch, and Figure 19 shows the wafer voltage Vsh, power supply output Vout, and ion current Ip.

[0119] When switching from the discharge phase to the application phase, the power supply output Vout changes from the ground potential of 0V to V1 according to the time constant of the smoothing circuit 14B, and a current Iq flows for a period of time tq. After time tq has elapsed, the power supply output Vout changes at a voltage change rate dV / dt, and the current Iq is maintained at a constant current.

[0120] At the end of the application phase, the power supply output Vout becomes voltage V2. This voltage V2 is determined by the voltage change rate dV / dt and the duration of the application phase. The duration of the gradient section of the application phase corresponds to the on-time Ton of the output pulse period T. [Industrial applicability]

[0121] The pulse power supply device of the present invention can be applied to plasma processing, as well as to loads that require a pulse output of a constant voltage. [Explanation of Symbols]

[0122] 1. Pulse power supply 2 Plasma Chamber 10 Power supply section 12, 12A, 12B Arbitrary waveform voltage generation unit 12b Inverter Circuit 12c transformer 12d rectifier circuit 12e Voltage Superposition Circuit 13 Switch section 13a Pulse switch section 13b Discharge circuit 14,14A,14B smoothing circuit 15 Control Unit 16 detectors 17 Discharge circuit 21 load Cf, Cp, Cw Capacitors Iout output current Ip ion current Lf, Lp inductor P0 Starting point P1, P2, Pk are points of refraction. P3 End Point Ph_dis discharge phase Ph_add application phase SWA, SWB Switch T Output pulse period Tinv Inverter Period Toff Off Time Tone On Time Vopt Output of arbitrary waveform voltage Vk Output Voltage V-line piecewise waveform voltage Vo Output Voltage Vout Power output Vsh wafer voltage dV / dt: Voltage change rate f_inv drive frequency f_pulse Output pulse frequency ΔV voltage difference

Claims

1. A first DC power supply that generates a first DC voltage, An arbitrary waveform voltage generation unit generates an arbitrary waveform voltage using multiple linear waveforms connecting two voltages, A switch unit that generates a pulse waveform by switching between the ground potential and the arbitrary waveform voltage, and outputs a pulse by repeating the pulse waveform at a predetermined period, Equipped with, The arbitrary waveform voltage generation unit is, By using inverter control, a piecewise linear waveform voltage is generated by linking multiple linear waveform voltages with different voltage change rates dV / dt, starting from the ground potential. The aforementioned piecewise linear waveform voltage and the first voltage are superimposed to generate an arbitrary waveform voltage. The arbitrary waveform voltage is the output voltage during the pulse application phase. The voltage at the start of the aforementioned application phase is the first voltage. The voltage at the end of the application phase is the voltage obtained by biasing the termination voltage of the piecewise linear waveform voltage with the first voltage. Pulse power supply.

2. The arbitrary waveform voltage generation unit is, Second DC power supply and An inverter circuit that converts the DC voltage of the second DC power supply to an AC voltage, A rectifier circuit that converts the AC voltage of the inverter circuit to a DC voltage, A voltage superposition circuit that superimposes the output of the first DC power supply and the output of the rectifier circuit, Equipped with, The inverter circuit adjusts the time width of the application phase, the inflection point for switching between the piecewise linear waveform voltage and the linear waveform voltage, the voltage change rate dV / dt of each linear waveform voltage, or the voltage at the inflection point in the DC-AC voltage conversion. The rectifier circuit rectifies the output of the inverter circuit to generate a piecewise linear waveform voltage. The voltage superposition circuit superimposes the first voltage of the output of the first DC power supply and the piecewise linear waveform voltage of the output of the rectifier circuit, using the first voltage of the first DC power supply as the starting voltage, and generating an arbitrary waveform voltage in which a plurality of linear waveform voltages with different voltage change rates dV / dt switch and connect at the inflection point. The pulse power supply device according to claim 1.

3. The system includes a control unit that controls the inverter circuit, The control unit includes control values ​​that define the time width of the application phase, the time between inflection points that switch the linear waveform voltage of the piecewise linear waveform voltage, and the voltage change rate dV / dt of each linear waveform voltage, or the voltage at the inflection point, and performs inverter control based on the control values ​​to generate a piecewise linear waveform voltage formed by linking multiple linear waveform voltages. The pulse power supply device according to claim 2.

4. The system includes a control unit that controls the inverter circuit, The control unit feeds back the power supply output Vout and / or output current Iout, and determines the time width of the application phase, the time and voltage of the inflection point that switches the linear waveform voltage of the piecewise linear waveform voltage, and the control value of the duty cycle that determines each linear waveform voltage, so that the power supply output Vout or output current Iout is a constant value. Based on the aforementioned control value, inverter control is performed to generate a piecewise linear waveform voltage, which is formed by concatenating multiple linear waveform voltages. The pulse power supply device according to claim 2.

5. The voltage superposition circuit is provided in the rectifier circuit, The output terminal of the first DC power supply is connected to one of the output terminals of the rectifier circuit. The pulse power supply device according to claim 2.

6. A transformer is provided between the inverter circuit and the rectifier circuit. The voltage superposition circuit is provided in the transformer. The output terminal of the first DC power supply is connected to one end of the secondary side of the transformer. The pulse power supply device according to claim 2.

7. The control unit, at each point in time when the time between the refraction points reaches the control value of the time between the refraction points, sets the control value of the voltage change rate dV / dt as the slope of the linear waveform voltage, and sequentially switches the linear waveform voltage of the piecewise linear waveform voltage to generate a piecewise linear waveform voltage. The pulse power supply device according to claim 3.

8. The control unit, at each point in time when the time between refraction points reaches the control value of the time between refraction points, uses the slope determined based on the control value of the voltage at the refraction point at that point and the next point in time, and the control value of the time between refraction points, as the slope of the linear waveform voltage, and sequentially switches the linear waveform voltage of the piecewise linear waveform voltage to generate a piecewise linear waveform voltage. The pulse power supply device according to claim 3.

9. The control unit, at each point in time when the time between the refraction points reaches the control value of the time between the refraction points, determines the voltage fluctuation by comparing the control value of the voltage at the refraction point at that point with the detected value of the output voltage at that point, When determining voltage fluctuations, the slope determined based on the detected output voltage at that time and the control value of the voltage at the next inflection point is defined as the slope of the linear waveform voltage, and the linear waveform voltage of the piecewise linear waveform voltage is sequentially switched to generate the piecewise linear waveform voltage. The pulse power supply device according to claim 3.

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