JP2021064482A - High frequency power supply device - Google Patents

Abstract

To provide a technique for reducing a periodic fluctuation of a plasma load when the periodic fluctuation of the plasma load occurs in a plasma processing apparatus to which a high frequency power supply device is connected.SOLUTION: A high frequency power supply device includes an oscillator for generating and outputting a high frequency oscillation signal based on a frequency set value, a power amplification unit for amplifying the high frequency oscillation signal by using DC power, and outputting a high-frequency output, a high frequency power detector for detecting a traveling wave power signal which is a high frequency output supplied to a load, and a reflected wave power signal from the load, and a controller for controlling the operation of the device to calculate a target power set value based on a setting parameter, and execute at least one of output power modulation and output frequency modulation on the target power set value to output a modulated high frequency output.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a high frequency power supply device.

In the high frequency power supply device, when the plasma load becomes unstable, control is performed so as to provide a constant power. For example, Patent Document 1 is for preventing fluctuations in output control and fluctuations in high-frequency output when low-frequency fluctuations occur in the load of a high-frequency power supply device that supplies high-frequency power to a plasma load or the like. , Discloses that it operates a feedback control or feedforward control loop that controls (regulates) internal voltage and current.

Japanese Unexamined Patent Publication No. 2013-77505

However, even if the high-frequency power supply device shown in Patent Document 1 is used to stably supply a constant power (high-frequency output) to a plasma load or the like at a predetermined frequency, the plasma load may be relatively low. Periodic load fluctuations (Plasma Oscillation) that fluctuate in low cycles may occur. This plasma oscillation fluctuates in a relatively low period (several Hz: for example, 3 to 6 Hz), and becomes a factor that causes plasma flicker (Blinking) in the plasma processing apparatus. If such plasma flicker occurs, for example, it becomes impossible to properly perform processing such as formation of a thin film on a semiconductor or liquid crystal by a plasma processing device, surface modification, or removal of the thin film (etching or ashing). there is a possibility.

The present disclosure has been made in view of such a situation, and provides a technique for reducing the periodic fluctuation of the plasma load when the periodic fluctuation of the plasma load occurs in the plasma processing apparatus to which the high frequency power supply device is connected. ..

In order to solve the above problems, the present embodiment is a high-frequency power supply device that supplies a high-frequency output to a load, and generates and outputs a high-frequency oscillation signal based on a frequency setting value, and a DC power source. A power amplification unit that amplifies a high-frequency oscillation signal and outputs a high-frequency output, a traveling wave power signal that is a high-frequency output supplied to the load, and a high-frequency power detection unit that detects a reflected wave power signal from the load. The target power setting value is calculated based on the setting parameter, and at least one of output power modulation or output frequency modulation is executed for the target power setting value to control the device operation so as to output a modulated high frequency output. A high-frequency power supply device including a control unit is disclosed.

Further features relating to this disclosure will become apparent from the description herein and the accompanying drawings. Moreover, the aspect of the present disclosure is achieved and realized by the mode of the elements and the combination of various elements, the detailed description below, and the appended claims.
The description of the present specification is merely a typical example, and does not limit the scope of claims or application examples of the present disclosure in any sense.

According to the present disclosure, it is possible to reduce the periodic fluctuation of the plasma load in the plasma processing apparatus to which the high frequency power supply apparatus is connected.

It is a block diagram which shows the schematic structure example of the high frequency power source device 10 by this embodiment. It is a figure which shows the internal structure example of the control part 17 by this embodiment. It is a figure which shows the internal structure example of the oscillation part 12 by this embodiment. It is a figure which shows the configuration example of the parameter setting screen 400 by this embodiment. It is a flowchart for demonstrating the detail of the modulation function in the high frequency power source device 10 of this embodiment. It is a figure which shows the example of the output power waveform when only output power modulation is performed. It is a figure which shows the example of the output power waveform when only output frequency modulation is performed. It is a figure which shows the example of the output power waveform when both output power modulation and output frequency modulation are performed. It is a graph which shows the frequency spectrum in the state where plasma oscillation occurs (before modulation). It is a graph which shows the frequency spectrum after performing the output power modulation in the state of FIG. It is a graph which shows the frequency spectrum in the state where plasma oscillation occurs (before modulation). It is a graph which shows the frequency spectrum after performing the output frequency modulation in the state of FIG.

<Structure of high frequency power supply device>
FIG. 1 is a block diagram showing a schematic configuration example of the high frequency power supply device 10 according to the present embodiment. As shown in FIG. 1, the high-frequency power supply device 10 includes a DC power supply unit 11, an oscillation unit 12, a power amplification unit 13, a synthesis unit 14, a high-frequency power detection unit 15, a control unit 17, and an input unit. A high frequency output (RF output) is supplied to a load 30 such as a plasma processing device via an impedance matching device 16 including 18 and a display unit 19.

The DC power supply unit 11 converts the output of the commercial power supply 20 into a DC output in response to an operation command from the control unit 17. The DC power supply unit 11 functions, for example, as a DC / DC converter that temporarily converts the AC voltage from the commercial power supply 20 into DC and then converts it into another level of DC output, and appropriately adjusts the level of the DC output. It is configured so that it can be controlled variably. The DC power supply unit 11 has an internal configuration (not shown in FIG. 1), for example, a rectifier circuit that rectifies an AC voltage obtained from a commercial power supply 20, an inverter that converts the output of the rectifier circuit into an AC output, and an inverter. A rectifying smoothing circuit that rectifies and smoothes the output of the inverter can be included.

The oscillator 12 receives each modulation parameter value (described later) including the oscillator output frequency set value (basic frequency) from the control unit 17, and supplies a signal (supplied to the load) of the AC component of the fundamental frequency or the frequency-modulated AC component. An oscillation signal equal to the frequency of the high-frequency output (high-frequency oscillation signal): a so-called small signal), and a signal for operating the power amplification unit 13 is supplied to the power amplification unit 13. When the high-frequency power supply device 10 is provided with a plurality of power amplification units 13, the oscillation unit 12 distributes and outputs the generated high-frequency oscillation signal by the set number of the power amplification units 13. FIG. 1 shows an example in which two high-frequency oscillation signals are output. Of course, one high-frequency oscillation signal may be output, or three or more high-frequency oscillation signals may be output.

The power amplification unit 13 amplifies the high-frequency oscillation signal supplied from the oscillation unit 12 based on the value of the operation amount supplied from the control unit 17 (described later), and determines the DC output supplied from the DC power supply unit 11. It is converted to high frequency power (RF output) having the frequency of and output. Although not shown in FIG. 1, a plurality of power amplification units 13 can be provided. Since the amount of power that can be output by only one power amplification unit is limited, a plurality of power amplification units may be provided in order to obtain a desired power value. That is, the number of power amplification units is determined by the magnitude of the output power required for the load connected to the high-frequency power supply device 10. In FIG. 1, since the two high-frequency oscillation signals are supplied to the power amplification unit 13, the two power amplification units are provided.

When there are a plurality of power amplification units 13, the synthesis unit 14 synthesizes the outputs of the power amplification units 13 and outputs a combined power signal (progressive wave power signal). Therefore, when there is only one power amplification unit 13, the synthesis unit 14 can be omitted. When a plurality of power amplification units 13 are provided, for example, as shown in JP-A-2015-144505 and JP-A-2017-201630, a phase difference is added to a plurality of high-frequency oscillation signals generated by the oscillation unit 12. By setting, the synthesis ratio in the synthesis unit 14 described later can be adjusted. That is, the high frequency power (RF output) output from the high frequency power supply device 10 can be adjusted.

The high-frequency power detection unit 15 supplies the high-frequency output (RF output: traveling wave power signal) generated by the synthesis unit 14 to a load 30 such as a plasma load (plasma processing device) via an impedance matching device 16.

The impedance matching box 16 has a function of matching the output impedance on the high frequency power supply device side with the input impedance on the load side when the load 30 is connected to the high frequency power supply device 10. This is for efficient power transmission. The impedance matching box 16 includes, for example, two variable capacitors, or one fixed capacitor and one variable capacitor. Even if impedance matching is achieved and the reflected wave power signal disappears, the above-mentioned plasma oscillation may occur.

The high-frequency power detection unit 15 detects not only the traveling wave power signal to be transmitted but also the reflected wave power signal reflected from the load 30 and returned when the impedance matching device 16 cannot complete the impedance matching, and the traveling wave power is detected. The signal and the reflected power signal are supplied to the control unit 17.

The control unit 17 determines the output control amount of the DC power supply unit 11 and the oscillation unit 12 based on the instruction input from the input unit 18, the traveling wave power signal and the reflected wave power signal supplied from the high frequency power wave detection unit 15. The operation basic frequency value of the above and the operation amount of the power amplification unit 13 are determined, and the respective control amounts are output for each. The operation amount of the power amplification unit 13 also includes a phase difference set for a plurality of high-frequency oscillation signals generated by the oscillation unit 12 described above.

When the impedance matching box 16 is an automatic impedance matching device, when the control unit 17 detects the occurrence of plasma oscillation, the output power (amplitude) modulation (high frequency output power modulation) processing and / or output according to the present embodiment is performed. In order to make the effect (described later) of the frequency modulation (high frequency output frequency modulation) process easy to understand, the operation of the automatic impedance matching box 16 may be stopped. Therefore, in FIG. 1, a control signal is supplied from the control unit 17 to the impedance matching box 16. Therefore, if the operation of the impedance matching box 16 is not stopped, it is not necessary to supply the control signal. The internal configuration of the control unit 17 is as shown in FIG. 2, and the details thereof will be described later.

The input unit 18 is a means for a user (operator) to input an instruction to the control unit 17, and corresponds to, for example, a keyboard, a mechanical switch, a pointing device such as a mouse or a touch panel, a microphone, or the like. As will be described later, the instruction input by the user includes, for example, a target power set value (reference power value), various output power modulation parameters, and various output frequency modulation parameters.

The display unit 19 displays, for example, a GUI (Graphical User Interface) for inputting various output power modulation and output frequency modulation parameters based on a command of the control unit 17, or an RF output level being supplied to a load. It displays detected traveling wave power signal value and reflected wave power signal value, presence / absence of plasma oscillation, output power modulation and / or information indicating that output frequency modulation is in operation.

<Example of internal configuration of control unit>
FIG. 2 is a diagram showing an example of the internal configuration of the control unit 17 according to the present embodiment. As shown in FIG. 2, the control unit 17 provides an operation amount (control amount) to the DC power supply unit 11 and the power amplification unit 13, and an output frequency modulation parameter for the oscillation unit 12. It is provided with a second component for supplying the above.

(I) About the first component The control unit 17 has, as the first component, an output power setting modulation unit 1701, an average power setting output unit 1702, and an output power modulation enable / disable setting output unit 1703. , Output power modulation amplitude setting output unit 1704, output power modulation phase setting output unit 1705, output power modulation frequency setting output unit 1706, and output power setting modulation output unit modulated and determined based on various parameters. To the power amplification unit based on the target power setting output unit 1708 that outputs the power set value as the target power set value, the traveling wave power signal and the reflected wave power signal acquired from the high frequency power detection unit 15, and the target power set value. The operation amount calculation unit 1709 for calculating the operation amount (feedback control amount) is provided.

The average power setting output unit 1702 supplies a set value (also referred to as an average value or a center value) of high frequency power (RF output) to be supplied to the load 30 to the output power setting modulation unit 1701. The set value may be input by the user via the input unit 18, or the average power setting output unit 1702 may read and acquire the value stored in the memory (not shown). ..

Output power modulation enable / disable setting In the output unit 1703, the output power setting value (output power value) is set with respect to a predetermined threshold value (for example, modulation start threshold setting power input unit 402 (see FIG. 4)). When the user exceeds the power value at which the possibility of plasma oscillation is likely to occur can be set as a threshold), information indicating whether or not to execute the output power modulation is supplied to the output power setting modulation unit 1701. To do. Whether it is enabled or disabled can be set by the user using the input unit 18, for example. The output power setting modulation unit 1701 executes the output power modulation when it receives the enable information, and does not execute the output power modulation when it receives the disable information. Whether it is enabled or disabled can be set by the user, for example, using the input unit 18 via the parameter setting screen 400 (see FIG. 4). As will be described later, the modulation target signal (modulation type information) is sent from the input unit 18 to the output power modulation enable / disable setting output unit 1703 of the control unit 17. Output power modulation enable / disable setting The output unit 1703 determines whether the output power modulation is enabled based on the modulation target signal, and outputs when the occurrence of plasma oscillation or the like is detected. Information on whether or not the power modulation operates is appropriately passed to the output power setting modulation unit 1701 (may be passed at the time of parameter setting, or may be passed when the occurrence of plasma oscillation or the like is detected).

The output power modulation amplitude setting output unit 1704 supplies an amplitude value (set value) at the time of output power modulation to the output power setting modulation unit 1701. The output power modulation phase setting output unit 1705 supplies a phase value (set value) at the time of output power modulation to the output power setting modulation unit 1701. Further, the output power modulation frequency setting output unit 1706 supplies the frequency value (set value) at the time of output power modulation to the output power setting modulation unit 1701. The set value of each of these output modulation parameters is set by the user using the input unit 18, for example (any value may be input, or a predetermined combination of each parameter value is selected. May be). When the output power setting modulation unit 1701 receives the enable information using various power modulation parameters received from each setting output unit 1704 to 1706, the output power setting modulation unit 1701 executes the output power modulation, and the output power modulation target. The power set value (power value to be aimed at as high frequency output) is output to the target power setting output unit 1708.

The target power setting output unit 1708 holds the output power modulated target power set value received from the output power setting modulation unit 1701, and for example, the output power modulation is performed by the operation amount calculation unit 1709 at the timing of starting the operation amount calculation process. Provides a set target power setting. When the target power setting output unit 1708 provides the output power-modulated target power setting value to the operation amount calculation unit 1709, the target power setting value may be deleted, or the next output power-modulated target power setting may be deleted. The target power setting value may be deleted by delaying the timing such as after providing the value.

The operation amount calculation unit 1709 provides the DC power supply unit 11 and the power amplification unit 13 with a variable that determines the output of the DC power supply unit 11 and a gain of the power amplification unit 13 as operation quantities, respectively. For example, the operation amount calculation unit 1709 uses the PWM control duty ratio of the inverter (not shown) that determines the output voltage of the DC power supply unit 11 as the operation amount, and controls the traveling wave power (constant control of the traveling wave power). ) Or, the active power obtained by subtracting the reflected wave power signal from the traveling wave power signal is set as the control target (constant load power control). The DC power supply unit 11 uses the manipulated variable to determine the DC power value to be output so that the average value of the high frequency power is maintained at the input average power set value. Further, for example, in the case of constant traveling wave power control, the operation amount calculation unit 1709 takes a difference between the output power modulated target power setting value and the detected traveling wave power signal (power value that changes from moment to moment). The operation amount (feedback control amount) is calculated, and the control amount is supplied to the power amplification unit 13. Each of the power amplification units 13 amplifies the high-frequency oscillation signal supplied from the oscillation unit 12 by using the operation amount received from the control unit 17 (operation amount calculation unit 1709), and the DC supplied from the DC power supply unit 11. The output is high frequency power (RF output) having a predetermined frequency.

(Ii) Second configuration unit The control unit 17 has, as the second configuration unit, an oscillation unit output frequency setting output unit 1710, an output frequency number modulation enable / disable setting output unit 1711, and an output frequency modulation amplitude. It includes a setting output unit 1712, an output frequency modulation phase setting output unit 1713, and an output frequency modulation frequency setting output unit 1714.

Oscillator unit output frequency setting The output unit 1710 provides the frequency (basic output frequency) of the high-frequency oscillation signal (small signal) output from the oscillator unit 12 to the output frequency modulation unit 1201 (see FIG. 3) of the oscillator unit 12. The frequency value of the high-frequency oscillation signal may be, for example, input by the user via the input unit 18, or a value stored in a memory (not shown) by the oscillation unit output frequency setting output unit 1710. It may be read and acquired.

Output frequency modulation enable / disable setting The output unit 1711 sets a threshold value for the output power setting value (for example, a threshold value can be set for a power value at which the possibility of plasma oscillation is high). When the value is exceeded, information indicating whether or not to execute the output frequency modulation is supplied to the output frequency modulation unit 1201 of the oscillation unit 12. As will be described later, whether to enable or disable can be set by the user, for example, using the input unit 18 via the parameter setting screen 400 (see FIG. 4). As will be described later, from the input unit 18, the modulation target signal (modulation type information: 0, 1, 2, 3 described above) is sent to the output frequency modulation enable / disable setting output unit 1711 of the control unit 17. It is sent, and under the control of the control unit 17, it is determined whether the output frequency modulation is effectively set (whether or not the frequency modulation is operated when the occurrence of plasma oscillation or the like is detected). Then, when the output frequency modulation is effectively set, the control unit 17 appropriately passes various output frequency modulation parameters to the output frequency modulation unit 1201 of the oscillation unit 12.

The output frequency modulation unit 1201 executes the output frequency modulation when it receives the enable information, and does not execute the frequency modulation when it receives the disable information.

The output frequency modulation amplitude setting output unit 1712 supplies an amplitude value (set value) at the time of output frequency modulation to the output frequency modulation unit 1201. Output frequency modulation phase setting The output unit 1713 supplies a phase value (set value) at the time of output frequency modulation to the output frequency modulation unit 1201. Further, the output frequency modulation frequency setting output unit 1714 supplies a frequency value (set value) at the time of output frequency modulation to the output frequency modulation unit 1201. The set value of each of these output modulation parameters is set by the user using the input unit 18, for example (any value may be input, or a predetermined combination of each parameter value is selected. May be).

In the present embodiment, various output power modulation parameters and various output frequency modulation parameters use values (fixed values) input by the user from the input unit 18 or read values (fixed values) stored in the memory. However, each parameter may be determined automatically. For example, after the occurrence of plasma oscillation is detected, signals for 1 to 2 cycles of high frequency output (RF output) may be acquired and the values of various modulation parameters may be automatically calculated.

<Example of internal configuration of oscillator>
FIG. 3 is a diagram showing an example of the internal configuration of the oscillator 12 according to the present embodiment. As shown in FIG. 3, the oscillation unit 12 includes an output frequency modulation unit 1201.

The output frequency modulation unit 1201 receives the output frequency modulation Enable / Disable signal, which is one of the various parameter values, and determines whether or not the output frequency modulation is effective. When the enable information is received, the output frequency modulation unit 1201 receives the basic output frequency received from the oscillation unit output frequency setting output unit 1710 and various output frequency modulations received from each of the other setting output units 1711 to 1714. Output frequency modulation is performed using the parameter values.

When the frequency modulation is disabled (Disable), the output frequency modulation unit 1201 does not execute the frequency modulation, and the oscillation unit 12 operates at the basic output frequency given by the oscillation unit output frequency setting output unit 1710. ..

As described above, the oscillating unit 12 outputs the oscillating unit output (high frequency oscillation signal) for the set number of power amplification units 13. Each power amplification unit 13 generates a high frequency output based on the high frequency oscillation signal received from the oscillation unit 12, the DC output received from the DC power supply unit 11, and the manipulated variable received from the control unit, and outputs the high frequency output to the synthesis unit 14. To do.

<Parameter setting screen configuration example>
In the modulation processing according to the present embodiment, the modulation target (modulation type) is selected, the output power modulation amplitude setting, the output power modulation frequency setting, the output power modulation phase setting, the output frequency modulation frequency amplitude setting, the output frequency modulation frequency setting, and the output. The frequency modulation phase setting and the modulation start threshold setting power are parameterized. For example, when the modulation target is set to output power modulation and the output power value to the load 30 exceeds the modulation start threshold set power, the high frequency power supply 1 has the output power modulation amplitude set value and the output power modulation frequency. Outputs high-frequency power according to the set value and output power modulation phase set value.

On the other hand, when the modulation target is set to output frequency modulation, when the output power value to the load 30 exceeds the modulation start threshold setting power, the high frequency power supply device 10 outputs the output frequency modulation frequency amplitude set value and output. Frequency modulation Outputs high frequency power according to the frequency setting value and output frequency modulation phase setting value.

The parameters can be set freely and can be optimized according to the condition (state) of plasma oscillation. In addition, the values of various parameters should be changed if the type of load changes. Hereinafter, a configuration example of the parameter setting screen for inputting various parameters as described above will be described.

FIG. 4 is a diagram showing a configuration example of the parameter setting screen 400 according to the present embodiment. The parameter setting screen 400 is, for example, a GUI (Graphical User Interface) displayed on the display screen of the display unit 19, and the value of each item is input by the user via the input unit 18.

The parameter setting screen 400 is, for example, a modulation target selection input unit 401, a modulation start threshold setting power input unit 402, an output power modulation amplitude setting value input unit 403, an output power modulation frequency setting value input unit 404, and an output power. Modulation phase setting value input unit 405, modulation restart instruction input unit 406 after arc detection, modulation restart instruction input unit 407 after stress detection, output frequency modulation frequency amplitude setting value input unit 408, output frequency modulation frequency setting value input A unit 409 and an output frequency modulation phase setting value input unit 410 are included as constituent items.

The modulation target selection input unit 401 is an item field used when the user inputs (selects) the type of modulation (modulation target) to be executed when the occurrence (or possibility of occurrence) of plasma oscillation is detected. is there. For example, "1" when executing only output power modulation, "2" when executing only high frequency output frequency modulation, "3" when executing both output power modulation and output frequency modulation, If neither is executed, it can be configured to input "0". Alternatively, the format may be such that information indicating the validity and invalidity of the output power modulation (1 or 0) and information indicating the validity and invalidity of the output frequency modulation (1 or 0) are input, respectively. Note that FIG. 4 shows a state in which "1", which is information indicating that only output power modulation is executed, is input (selected). Further, the value input from the modulation target selection input unit 401 (“0, 1, 2, or 3”, or “output power modulation is 1 or 0, and output frequency modulation is 1 or 0”) is a modulation target signal. It is sent to the control unit 17 as (information indicating the modulation type).

The modulation start threshold setting power input unit 402 is an item field for the user to detect the occurrence (or risk of occurrence) of plasma oscillation and input the threshold value of the set power for enabling the specified modulation. When the set power value (output power value) is equal to or greater than the threshold value, the modulation operation is executed. FIG. 4 shows a state in which 24.5 kW is input as a threshold value.

The output power modulation amplitude setting value input unit 403 is an item field for the user to input the amplitude power setting value at the time of output power modulation. Amplitude modulation is performed with the ± amplitude power setting. FIG. 4 shows a state in which 400 W is input as the amplitude set value.

The output power modulation frequency setting value input unit 404 is an item field for the user to input the modulation frequency setting value at the time of output power modulation. FIG. 4 shows a state in which 60 Hz is input as a frequency set value.

The output power modulation phase setting value input unit 405 is an item column for the user to input a phase setting value (information indicating how much the phase is shifted with respect to the modulation frequency) at the time of output power modulation. FIG. 4 shows a state in which the phase is not set (the set phase value is 0).

The modulation restart instruction input unit 406 after arc detection is an item field for the user to input information (set value) indicating whether or not to restart the modulation after detecting the arc (sudden load change) generated by the load 30. .. For example, when the set value is "0", the modulation operation after the arc detection is not restarted, and when the set value is "1", the modulation operation after the arc detection can be restarted. FIG. 4 shows a state in which the modulation operation after the arc is detected is specified to be restarted.

The post-stress modulation restart instruction input unit 407 is an item field for the user to input information (set value) indicating whether or not to restart the modulation after detecting the stress in the load 30. For example, when the set value is "0", it is possible to specify that the modulation operation after stress detection is not restarted, and when the set value is "1", the modulation operation after stress detection is restarted. FIG. 4 shows a state in which the modulation operation after stress detection is specified to be restarted.

The output frequency modulation frequency amplitude setting value input unit 408 is an item column for the user to input the frequency amplitude setting value at the time of output frequency modulation. Frequency modulation is performed with the center frequency ± frequency amplitude set value. FIG. 4 shows a state in which 10 Hz is input as the frequency amplitude set value.

The output frequency modulation frequency setting value input unit 409 is an item field for the user to input a frequency setting value (setting value for one cycle of modulation) at the time of output frequency modulation. FIG. 4 shows a state in which 60 Hz is input as a frequency set value.

The output frequency modulation phase setting value input unit 410 is an item for the user to input a phase setting value (information indicating the timing of starting the modulation operation (how much deviation the modulation is applied to)) at the time of output frequency modulation. It is a column. FIG. 4 shows a state in which the output frequency phase is not set (the set phase value is 0).

In FIG. 4, the output power modulation amplitude setting value input unit 403, the output power modulation frequency setting value input unit 404, and the output power modulation phase setting value input unit 405 are item columns related to parameter setting of high frequency output power modulation. , Output frequency modulation frequency amplitude setting value input unit 408, output frequency modulation frequency setting value input unit 409, and output frequency modulation phase setting value input unit 410 are item columns related to parameter setting of output frequency modulation.

<Details of modulation function>
FIG. 5 is a flowchart for explaining the details of the modulation function in the high frequency power supply device 10 of the present embodiment. For example, since the modulation function can be realized by a program, the control unit (processor such as a CPU) 17 reads the program from a memory (not shown), expands it into the internal memory in the processor, and operates the modulation function. Let me. Therefore, in the following, the operation of each step will be described assuming that the operation subject is the control unit 17.

(I) Step 501
The control unit 17 monitors the target power set value (output power set value) calculated by the output power setting modulation unit 1701 and determines whether or not the target output set value exceeds a predetermined threshold value (first threshold value). .. The predetermined threshold value is set to a voltage value when plasma oscillation occurs or is likely to occur, and is input and set by the user, for example, via the input unit 18. The predetermined threshold value can be determined, for example, based on an empirical rule regarding the timing of occurrence of plasma oscillation.

When it is determined that the monitored target power set value exceeds a predetermined threshold value (YES in step 501), the process proceeds to step 502. When it is determined that the monitored target power set value does not exceed a predetermined threshold value (NO in step 501), the process proceeds to step 508.

In the previous monitoring timing, even if it is determined that the target power set value exceeds (or exceeds) the predetermined threshold value and output power modulation and / or output frequency modulation is executed, the current monitoring timing When the target power set value becomes equal to or less than (or less than) the predetermined threshold value in step 501, NO is set in step 501, and the process proceeds to step 508. Further, in the present embodiment, when the target power set value exceeds a predetermined threshold value, it is determined that plasma oscillation may or may not occur. However, in addition to the target power set value, the load value and the phase The occurrence of plasma oscillation is determined based on the comparison between the value, γ (reflection coefficient of power) value, reflected wave power value, etc. (condition) and the threshold value (second threshold value) set in advance for each. You may. Further, a plurality of of these elements may be combined to determine the occurrence of plasma oscillation or the like.

(Ii) Step 502
The control unit 17 acquires information about whether or not the output power modulation is effective via the output power setting modulation unit 1701, and whether the output power modulation is effectively set based on the information (plasma oscillation). Whether or not to execute output power modulation when the occurrence etc. is detected) is determined. If it is determined that the output power modulation is valid (YES in step 502), the process proceeds to step 503. If it is determined that the output power modulation is invalid (NO in step 502), the process proceeds to step 504.

In the present embodiment, the information of the modulation target (modulation type) is input via the above-mentioned parameter setting screen 400, and the effectiveness of the output power modulation is determined based on the information, but the parameter setting screen 400 is displayed. On the other hand, in the case where the information on whether the high frequency output power modulation is valid or invalid is directly set as an input, the control unit 17 can directly determine whether the output power modulation is valid or not.

(Iii) Step 503
The control unit 17 acquires information on whether or not the output frequency modulation is effective, and whether or not the output frequency modulation is effectively set based on the information (when the occurrence of plasma oscillation or the like is detected, the output frequency is output. Whether or not to perform modulation) is determined. If it is determined that the output frequency modulation is valid (YES in step 503), the process proceeds to step 505. If it is determined that the output frequency modulation is invalid (NO in step 503), the process proceeds to step 506.

(Iv) Step 504
Similar to step 503, the control unit 17 acquires information on whether or not the output frequency modulation is effective, and whether or not the output frequency modulation is effectively set based on the information (detection of occurrence of plasma oscillation, etc.). If so, determine whether to perform output frequency modulation). If it is determined that the output frequency modulation is valid (YES in step 504), the process proceeds to step 507. If it is determined that the output frequency modulation is invalid (NO in step 504), the process proceeds to step 508.

(V) Step 505
The control unit 17 sets the output power modulation and the output frequency modulation to valid (ON). Then, the control unit 17 sets the average power setting value and various parameters of the output power modulation (output power modulation amplitude setting value, output power modulation phase setting value, and output power modulation frequency setting) with respect to the output power setting modulation unit 1701. Value). Further, the control unit 17 refers to the output frequency modulation unit 1201 of the oscillation unit 12 with respect to the oscillation unit output frequency set value (basic output frequency set value) and various frequency modulation parameters (output frequency modulation amplitude set value, output frequency). The modulation phase setting value and the output frequency modulation frequency setting value) are supplied.

(Vi) Step 506
The control unit 17 sets the output power modulation to valid (ON) and the output frequency modulation to invalid (OFF). Then, the control unit 17 sets the average power setting value and various parameters of the output power modulation (output power modulation amplitude setting value, output power modulation phase setting value, and output power modulation frequency setting) with respect to the output power setting modulation unit 1701. Value). Further, the control unit 17 does not supply various parameters of output frequency modulation to the output frequency modulation unit 1201 of the oscillation unit 12, but provides the oscillation unit output frequency set value (basic output frequency set value).

(Vii) Step 507
The control unit 17 sets the output power modulation to invalid (OFF) and the output frequency modulation to valid (ON). Then, the control unit 17 does not provide various parameters of the output power modulation to the output power setting modulation unit 1701, but supplies the average power setting value. Further, the control unit 17 refers to the output frequency modulation unit 1201 of the oscillation unit 12 with respect to the oscillation unit output frequency set value (basic output frequency set value) and various frequency modulation parameters (output frequency modulation amplitude set value, output frequency). The modulation phase setting value and the output frequency modulation frequency setting value) are supplied.

(Viii) Step 508
The control unit 17 sets the output power modulation and the output frequency modulation to invalid (OFF). Then, the control unit 17 does not provide various parameters of the output power modulation to the output power setting modulation unit 1701, supplies the average power setting value, and outputs the output to the output frequency modulation unit 1201 of the oscillation unit 12. Various parameters of frequency modulation are not provided, and the output frequency set value (basic output frequency set value) of the oscillating unit is supplied.

(Ix) Step 509
The modulation process set in steps 505 to 507 is executed.
(Ix-1) When the output power modulation is enabled (ON), the output power setting modulation unit 1701 sets the average power setting value acquired from the average power setting output unit 1702 under the control of the control unit 17 on the parameter setting screen. Output power modulation is performed with various output power modulation parameters (amplitude setting value, phase setting value, and frequency setting value) set in 400, a modulated average power setting value is generated, and output to the target power setting output unit 1708. To do. The target power setting output unit 1708 outputs the modulated average power set value as the target power set value to the operation amount calculation unit 1709.

The operation amount calculation unit 1709 calculates the operation amount of power amplification (for example, the size of a variable that determines the level of high-frequency power to be output) from the difference value between the target power set value and the traveling wave power signal value. The operation amount is output to the power amplification unit 13. Even if the output power modulation is performed, the average power value (center power value) is the same. Depending on the manipulated variable, it is possible to change the envelope of the output power value while keeping the high frequency output (RF output) at the target power set value (average power set value).

(Ix-2) When the output frequency modulation is enabled (ON), the control unit 17 is set on the oscillation unit output frequency value (basic output frequency setting value) and the parameter setting screen 400 set and input by the user from the input unit 18. The various output frequency modulation parameters (output frequency modulation frequency amplitude set value, output frequency modulation phase set value, and output frequency modulation frequency set value) are acquired and passed to the output frequency modulation unit 1201 of the oscillation unit 12.

The output frequency modulation unit 1201 modulates the basic output frequency with an output frequency based on various frequency parameters, generates a modulated high frequency oscillation signal (small signal), and outputs the modulated high frequency oscillation signal (small signal) to the power amplification unit 13.

(X) Step 510
In this case, since plasma oscillation has not occurred, or even if plasma oscillation has occurred, none of the modulations is set to be performed, so output power modulation and output frequency modulation are executed. Instead, a normal high frequency output generation process is executed, and the generated high frequency output (RF output) is supplied to the load 30.

Specifically, since various output power modulation parameters are not considered, the target power setting output unit 1708 provides the average power setting value as the target power setting value to the operation amount calculation unit 1709 under the control of the control unit 17. Then, under the control of the control unit 17, the operation amount calculation unit 1709 determines the operation amount of power amplification (for example, the level of high-frequency power to be output) from the difference value between the target power set value and the traveling wave power signal value. The size of the variable) is calculated, and the operation amount is output to the power amplification unit 13. The operation amount makes it possible to keep the high frequency output (RF output) at the target power set value (average power set value). Further, the oscillation unit 12 acquires the oscillation unit output frequency setting value (basic output frequency setting value) via the control unit 17, generates a high frequency oscillation signal (small signal) based on the acquisition, and outputs the high frequency oscillation signal (small signal) to the power amplification unit 13. To do.

<Example of output power waveform during modulation>
6 to 8 are diagrams showing an example of an output power waveform obtained when the modulation process according to the present embodiment is executed. FIG. 6 shows an example of an output power waveform when only output power modulation is performed. FIG. 7 shows an example of an output power waveform when only output frequency modulation is performed. FIG. 8 shows an example of an output power waveform when both output power modulation and output frequency modulation are performed.

(I) When only output power modulation is performed (see Fig. 6)
Output power modulation is started when the target power set value (output power set value) exceeds a predetermined threshold value. In the section where output power modulation is performed, the output power has the same center frequency (basic output frequency) as the output power before modulation, and the output envelope (amplitude) increases based on the amplitude value included in the modulation parameter. (Variable value), and the period of amplitude change is modulated by the frequency setting value included in the modulation parameter (phase setting value is 0). Since the center frequency is the same before and after the modulation, the output average power value is the same before and after the modulation. Then, referring to FIG. 6, when the target power set value falls below the above-mentioned predetermined threshold value after the output power modulation, the output power modulation is stopped and the output power value does not generate plasma oscillation. You can see that.

(Ii) When only output frequency modulation is performed (see Fig. 7)
Output frequency modulation is started when the target power set value exceeds a predetermined threshold. In the section where output frequency modulation is executed, the output power has the same center frequency (basic output frequency) as the output power before modulation, and the output envelope (amplitude) is based on the frequency amplitude set value included in the output frequency modulation parameter. ) Is increased (constant value), and the cycle of the output power is modulated by the frequency setting value included in the output frequency modulation parameter (phase setting value is 0). Since the center frequency is the same before and after the modulation, the output average power value is the same before and after the modulation. Then, referring to FIG. 7, when the target power set value falls below the above-mentioned predetermined threshold value after the output frequency modulation, the output frequency modulation is stopped and the output power value does not generate plasma oscillation. You can see that.

(Iii) When both output power modulation and output frequency modulation are performed (see FIG. 8).
Output frequency modulation and output power modulation are started when the target power set value exceeds a predetermined threshold value. In the section where output frequency modulation and output power are executed, the output power has the same center frequency (basic output frequency) as the output power before modulation, and the output envelope (amplitude) is included in the output power modulation parameter. It is modulated to increase based on the value (variable value), and the period of amplitude change is modulated by the output power modulation frequency set value included in the output power modulation parameter, and the cycle of output power becomes the output frequency modulation parameter. It is modulated by the included output frequency modulation frequency setting (in output power modulation and output frequency modulation, the phase setting is 0). Since the center frequency is the same before and after the modulation, the output average power value is the same before and after the modulation. Then, referring to FIG. 8, when the target power set value falls below the predetermined threshold value after the output power modulation, the output power modulation and the output frequency modulation are stopped, and the output that does not generate plasma oscillation is not generated. It can be seen that it is the power value.

<Comparison result of output power before and after modulation>
9 to 12 are graphs showing frequency spectra (Fourier transform values) before and after performing output power modulation or output frequency modulation. 9 and 11 are graphs showing frequency spectra in a state where plasma oscillation is occurring (before modulation). FIG. 10 is a graph showing a frequency spectrum after performing output power modulation in the state of FIG. FIG. 12 is a graph showing a frequency spectrum after performing output frequency modulation in the state of FIG.

(I) Effect of output power modulation As shown in FIG. 9, a component having a large amplitude level exists in the vicinity of 3 Hz. This is because the plasma oscillation is a periodic fluctuation that occurs in the load 30 at a low frequency of several Hz, and the power value component at the 3 Hz corresponds to the plasma oscillation.

Therefore, the output power modulation described in the present embodiment (for example, the output power modulation frequency setting value is 60 [Hz], the output power modulation amplitude setting value is ± 400 [W], and the output power modulation phase setting value is 0 [deg]. As shown in FIG. 10, it can be seen that the power value component of 3 Hz in which the plasma oscillation was generated is suppressed to a low level.

(Ii) Effect of output frequency modulation Similar to FIG. 9, in FIG. 11, a component having a large amplitude level exists in the vicinity of 3 Hz. As described, this is the state in which plasma oscillation is occurring.

In this state, the output frequency modulation described in the present embodiment (for example, the output frequency modulation frequency set value is 60 [Hz] and the output frequency modulation amplitude set value is ± 10 [kHz] (basic operating frequency (for example, 13.56 MHz)). ) ± 10kHz: The central frequency (basic frequency) of 13.56MHz is fluctuated by 10kHz, but it is fluctuated over a period of 60Hz per cycle.), The output power modulation phase setting value is set to 0 [deg]). As shown in FIG. 12, it can be seen that the power value component of 3 Hz in which plasma oscillation was generated is suppressed to a low level.

(Iii) In FIGS. 10 and 12, when the output power modulation or the output frequency modulation is performed, a peak that did not exist before the modulation appears in the vicinity of 60 Hz, but plasma oscillation does not occur due to this peak.

In the output power modulation, the amplitude set value is set to 400 W or more and 800 W or less (the effect is small if the amplitude value is less than 400 W, but if the amplitude value is raised too much, the power supply is overstressed), and in the output frequency modulation, the frequency is set. It was found that it is preferable to set the set value from 50 Hz to 70 Hz. When the load characteristics change, it is preferable to make various modulation parameters of output power modulation or output frequency modulation variable within this range.

<Modification example>
(I) When the impedance matching box 16 operates automatically (when the values of the two capacitors provided inside are variable), the operation and the modulation operation are superimposed, and which processing unit operates. , It may not be possible to know which processing unit is stopped. In addition, the effect of modulation (plasma oscillation suppression effect) may be difficult to understand. Therefore, the control unit 17 may control to stop the operation of the impedance matching device 16 when the occurrence or possibility of plasma oscillation is detected (control from the control unit 17 to the impedance matching device 16). See signal line).

(Ii) In the embodiment shown in FIGS. 9 to 12, the fundamental frequency is set to about 13 MHz, but it can be set to 400 kHz to 100 MHz or more. Even at such a fundamental frequency, the plasma oscillation suppression effect by executing the output modulation operation according to the present embodiment can be confirmed.

<Summary>
(I) In the high frequency power supply device according to the present embodiment, at least one of output power modulation and output frequency modulation is executed with respect to the target power set value calculated according to the setting parameter, and the modulated high frequency output is output. By configuring the high-frequency power supply device in this way, it is possible to reduce the plasma oscillation generated by the load 30 or prevent the plasma oscillation generated by the load 30. Whether or not to execute modulation can be first determined by, for example, whether or not the target power setting value exceeds a predetermined threshold value (first threshold value).

The high-frequency power supply device performs output power modulation or output frequency based on information indicating whether output power modulation and output frequency modulation are enabled or disabled (output power modulation Enable / Disable, output frequency modulation Enable / Disable). It acts to determine whether to perform one or both of the modulations. By doing so, the user can decide which modulation method to reduce or prevent plasma oscillation and use it properly according to the situation. The high frequency power supply also modulates the high frequency power target value based on the output power modulation parameters including the output power modulation amplitude value and the output power modulation frequency value input by the user, and / or input by the user. The high frequency oscillation signal is modulated based on the output frequency modulation parameters including the output frequency modulation amplitude value and the output frequency modulation frequency value. In this way, the user can change the modulation parameter as appropriate by changing which parameter, and the range of discretion of the user is widened.

The occurrence or risk of low-period fluctuations is determined by predetermined conditions (for example, output power value, phase value, reflection coefficient value, reflected power value) in the traveling wave power signal supplied to the load or the reflected wave power signal from the load. Etc.) and a predetermined threshold value (second threshold value) set in advance, and the detection is performed based on the comparison result. The threshold value for each of these conditions is configured so that the user can set it via the GUI. For example, when a traveling wave power signal is used, the high-frequency power supply device detects the occurrence or possibility of occurrence of low-period fluctuations in the load when the detected traveling wave power signal exceeds a preset threshold value. At least one of output power modulation and output frequency modulation is performed depending on the detection result. By doing so, it is possible to directly suppress the value of the output high-frequency power signal by modulation.

When the high-frequency power supply device executes output power modulation, the high-frequency power supply unit calculates the operation amount in the power amplification unit from the difference value between the modulated target power setting value and the high-frequency output supplied to the load, and uses the operation amount as the power amplification unit. It is reflected in the power amplification operation in.

(Ii) The present disclosure can also be realized by a program code of software that realizes the functions of the embodiment. In this case, a storage medium in which the program code is recorded is provided to the system or device, and the computer (or CPU or MPU) of the system or device reads the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the program code itself and the storage medium storing the program code itself constitute the present disclosure. Examples of the storage medium for supplying such a program code include a flexible disk, a CD-ROM, a DVD-ROM, a hard disk, an optical disk, a magneto-optical disk, a CD-R, a magnetic tape, a non-volatile memory card, and a ROM. Etc. are used.

Further, based on the instruction of the program code, the OS (operating system) or the like running on the computer performs a part or all of the actual processing, and the processing enables the functions of the above-described embodiment to be realized. You may. Further, after the program code read from the storage medium is written in the memory on the computer, the CPU of the computer or the like performs a part or all of the actual processing based on the instruction of the program code, and the processing is performed. May realize the function of the above-described embodiment.

Further, by distributing the program code of the software that realizes the functions of the embodiment via a network (not shown in the attached drawing), it is distributed by a storage means such as a hard disk or memory of the system or device or a CD-RW. , CD-R or the like, and the computer (or CPU or MPU) of the system or device may read and execute the program code stored in the storage means or the storage medium at the time of use. ..

Finally, it should be understood that the processes and techniques described here are not essentially associated with any particular device and can be implemented with any suitable combination of components. In addition, various types of devices for general purpose can be used according to what is described herein. It may be beneficial to build a dedicated device to perform the steps of the method described here. In addition, various inventions can be formed by appropriately combining the plurality of components disclosed in the embodiments. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate. The present disclosure has been described in connection with specific examples, but these are for illustration purposes only, not for limitation in all respects. Those skilled in the art will find that there are numerous combinations of hardware, software, and firmware suitable for implementing this disclosure. For example, the described software can be implemented in a wide range of programs or scripting languages such as assembler, C / C ++, perl, Shell, PHP, Java®.

Further, in the above-described embodiment, the control lines and information lines are shown as necessary for explanation, and the product does not necessarily show all the control lines and information lines. All configurations may be interconnected.

10 High-frequency power supply device 11 DC power supply unit 12 Oscillator unit 13 Power amplification unit 14 Synthesis unit 15 High-frequency power detection unit 16 Impedance matching box 17 Control unit 18 Input unit 19 Display unit 20 Commercial power supply 30 Load

Claims (8)

A high-frequency power supply that supplies high-frequency output to the load.
An oscillator that generates and outputs a high-frequency oscillation signal based on the frequency setting value,
A power amplification unit that amplifies the high-frequency oscillation signal using DC power and outputs a high-frequency output,
A traveling wave power signal that is a high-frequency output supplied to the load, a high-frequency power detector that detects a reflected wave power signal from the load, and a high-frequency power detector.
The target power setting value is calculated based on the setting parameter, and at least one of output power modulation and output frequency modulation is executed for the target power setting value to control the device operation so as to output a modulated high frequency output. Control unit and
High frequency power supply with. In claim 1,
The control unit determines whether or not the target power set value exceeds the first threshold value, and determines whether to execute the output power modulation or the output frequency modulation according to the determination result. In claim 1 or 2,
Whether the control unit executes either or both of the output power modulation and the output frequency modulation based on the set input information indicating whether the output power modulation and the output frequency modulation are valid or invalid. To determine the high frequency power supply. In any one of claims 1 to 3,
The control unit is a high-frequency power supply device that modulates a high-frequency power target value based on an output power modulation parameter including an output power modulation amplitude value and an output power modulation frequency value. In any one of claims 1 to 4,
The control unit is a high-frequency power supply device that modulates the high-frequency oscillation signal based on an output frequency modulation parameter including an output frequency modulation amplitude value and an output frequency modulation frequency value. In any one of claims 1 to 5,
The control unit has a low period in the load based on a comparison result between a predetermined condition in the traveling wave power signal supplied to the load or the reflected wave power signal from the load and a preset second threshold value. A high-frequency power supply that detects the occurrence or possibility of fluctuations. In any one of claims 1 to 6,
The control unit detects the occurrence or possibility of occurrence of low-period fluctuations in the load based on the detected traveling wave power signal, and depending on the result of the detection, the output power modulation or the output frequency modulation. A high frequency power supply that controls device operation to perform at least one of the above. In any one of claims 1 to 7,
When the output power modulation is performed, the control unit calculates the operation amount in the power amplification unit from the difference value between the modulated target power set value and the high frequency output supplied to the load, and calculates the operation amount. A high-frequency power supply that outputs to the power amplification unit.

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