High frequency power supply system

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

In the field of semiconductor manufacturing, high-density packaging is required as electronic equipment becomes smaller and more sophisticated, and the connection of elements to mounting boards becomes smaller, requiring more reliable packaging. ing.

One method for ensuring reliability of packaging is surface modification using plasma. For example, when a substrate to be processed is subjected to plasma treatment, it is possible to remove contamination caused by organic matter adhering to the surface of the substrate, improve the bonding strength of wire bonding, improve wettability, and improve the adhesion between the substrate and the sealing resin. can be improved. In order to perform such plasma processing, it is necessary to connect a power supply device to the plasma reactor device.

For example, Patent Document 1 discloses a configuration example of a power supply device connected to a plasma reactor device. Specifically, Patent Document 1 discloses a configuration in which a high frequency (source) power source and a low frequency (bias) power source are superimposed and supplied to a plasma reactor device via a matching circuit. In a matching circuit, an attempt is made to realize efficient power supply by matching the impedance between the power supply side and the plasma reactance device side.

<p><patcit num="1"><text>Japanese Patent Application Publication No. 7-74159</text></patcit></p>

<p>It is known that when a two-frequency power source is supplied as shown in Patent Document 1, a plasma sheath is generated along with plasma in a plasma chamber of a plasma reactor device. This plasma sheath can be generally considered to be electrically insulated, and can be seen as a virtual capacitor being formed between the electrodes of the plasma chamber. Since the plasma position changes in conjunction with periodic changes in the voltage of the low-frequency (bias) power supply, the capacitance of the plasma sheath also changes periodically (for example, due to the structure of the plasma chamber, the bias (varies at the same or twice the frequency). This means that the plasma impedance changes rapidly due to changes in the voltage of the bias power supply.</p><p>However, since the variable impedance element in the matching box is operated by a motor, the matching operation cannot follow rapid changes in plasma impedance. As a result, the amount of reflected wave power Pr that returns to the output end of the source power source increases due to inter-modulation distortion (IMD). If reflected waves increase, power cannot be efficiently and accurately supplied to the load side, so it is necessary to reduce IMD.</p><p>In view of this situation, the present disclosure proposes a technique for suppressing an increase in reflected wave power Pr (synonymous with reflection coefficient) due to IMD.</p>

<p>In order to solve the above problems, the present disclosure provides a high frequency power supply system that provides high frequency power to a connected load, including a bias power supply that outputs bias power at a first frequency, and a bias power supply that outputs bias power at a frequency higher than the first frequency. A source power source that outputs source power at a high second frequency, and a matching device that includes an impedance matching circuit that obtains bias power and source power and matches the impedance of the source power source and the impedance of the load side. , the source power supply supplies the bias power supply with a sine wave synchronization signal containing information on the output frequency that the bias power supply should output, and the bias power supply supplies bias power at a frequency corresponding to the output frequency included in the sinusoidal synchronization signal. The matching device divides the traveling wave power for one cycle of the bias power from the source power source and the reflected wave power to the source power source into multiple sections, and performs frequency matching for each of the multiple sections. A calculation is performed to determine the frequency setting value for each section, and a process for transmitting the frequency setting value for each section to the source power supply is executed. A high frequency power supply system is provided that outputs bias power in a plurality of sections according to frequency setting values of the sections.</p><p>Further features related to the present disclosure will become apparent from the description herein and the accompanying drawings. Aspects of the present disclosure may also be accomplished and realized by means of the elements and combinations of various elements, as well as aspects of the following detailed description and appended claims.</p><p>It should be understood that the description herein is merely a typical example and does not limit the scope of the claims or the examples of application in any way.</p>

<p>According to the technology of the present disclosure, in a power supply device that provides dual-frequency power, IMD generated on the load side can be reduced, and an increase in reflected power (reflection coefficient) due to IMD can be suppressed.</p>

<figref num="1">1 is a diagram showing a state in which a plasma load 40 is connected to a power supply system (also referred to as a high frequency power system) 1 according to the present embodiment. FIG.</figref><figref num="2">FIG. 3 is a diagram showing an example of the configuration of a three-dimensional S-parameter table that provides S-parameters corresponding to the position and frequency (frequency deviation amount) of a variable capacitor. Table 1 shows a position-characteristic parameter table, and Table 2 shows a frequency (deviation amount from the fundamental frequency)-characteristic parameter.</figref><figref num="3A">2 is a flowchart (first half) for explaining in detail the frequency matching calculation process by the power supply system 1 according to the present embodiment.</figref><figref num="3B">3 is a flowchart (second half) for explaining in detail the frequency matching calculation process by the power supply system 1 according to the present embodiment.</figref><figref num="4">3A and 3B are timing charts of a process (frequency setting calculation process) for obtaining frequency-matched frequency setting values described in FIGS. 3A and 3B, according to the present embodiment. FIG.</figref>

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. In the accompanying drawings, functionally similar elements may be designated by the same number. Although the attached drawings show specific embodiments and implementation examples in accordance with the principles of the present disclosure, they are for the purpose of understanding the present disclosure, and are not to be construed as limiting the present disclosure in any way. It is not used.

Although the embodiments are described in sufficient detail for those skilled in the art to implement the present disclosure, other implementations and forms are possible without departing from the scope and spirit of the technical idea of the present disclosure. It is necessary to understand that it is possible to change the composition and structure and replace various elements. Therefore, the following description should not be interpreted as being limited to this.

Further, embodiments of the present disclosure may be implemented in software running on a general-purpose computer, dedicated hardware, or a combination of software and hardware.

&lt;Configuration Example of Power Supply System 1&gt; (i) Configuration Example 1 FIG. 1 is a diagram showing a state in which a plasma load 40 is connected to a power supply system (also referred to as a high frequency power system) 1 according to the present embodiment. The power supply system 1 has a source power supply (supplies high-frequency output) 10, a bias power supply (supplies low-frequency output) 20, and outputs are supplied from each of the source power supply 10 and the bias power supply 20. A matching box (also referred to as an impedance conversion device) 30 that performs impedance matching between the 20 side and the plasma load 40 side; This is a system that supplies power (bias power) to the plasma load 40 in a superimposed manner, for example.

Although FIG. 1 shows only the sine wave synchronization signal generator 101 as the internal configuration of the source power supply 10, typical internal configurations include, for example, an RF amplifier, a sensor (directional coupler), and a control device. etc. are included. The RF amplifier amplifies a high frequency signal of a predetermined frequency (eg, 13.56 MHz, 27.12 MHz, 40.68 MHz, 60 MHz, 100 MHz, 120 MHz, etc.) in response to a control signal from a control device, and supplies the signal to the sensor. For example, the sensor detects the high frequency output (traveling wave power Pf) from the RF amplifier, and also detects the reflected wave power Pr from the matching box 30 and the voltage component of the traveling wave power Pf and the voltage component of the reflected wave power Pr. Detect phase difference. Further, the sensor may be configured to output the traveling wave power Pf to the matching box 30, and also output the detected traveling wave power Pf value, reflected wave power Pr, and phase signal to the control device. A sine wave synchronization signal generating section 101 in the source power supply 10 outputs to the bias power supply 20 information on the frequency and phase (for example, a 400 kHz sine wave) at which the bias power supply 20 should operate in synchronization.

Further, although FIG. 1 only shows the sine wave synchronization signal receiving section 201 as the internal configuration of the bias power supply 20, similar to the source power supply 10, the general internal configuration includes an RF amplifier, a sensor (directional (coupler), control device, etc. The sine wave synchronization signal receiving section 201 in the bias power supply 20 extracts frequency and phase information included in the sine wave synchronization signal supplied from the source power supply 10. Then, the oscillator of the bias power supply 20 outputs traveling wave power (RF output) in synchronization with the extracted frequency and phase, and supplies it to the matching unit 30.

The matching box 30 includes a sensor 1_301, a sensor 2_302, a frequency setting calculation section 303, a matching calculation section 1_304, a matching calculation section 2_305, a matching network 1_306, a matching network 2_307, and an output sensor 308. There is. Sensor 1_301 detects the traveling wave power Pf supplied from the source power supply 10 on the high frequency side and the reflected wave power Pr returning from the plasma load 40, and provides them to the frequency setting calculation unit 303.

Sensor 2_302 detects the traveling wave power Pf supplied from the bias power supply 20 on the low frequency side and the reflected wave power Pr returning from the plasma load 40, and outputs them (including information on the phase of the traveling wave power Pf). Provided to frequency setting calculation section 303.

The frequency setting calculation unit 303 synchronizes with the phase of the traveling wave power Pf on the low frequency (bias power supply 20) side, and outputs the output of the source power supply 10 for one cycle of the operating frequency (for example, 400 kHz) of the bias power supply 20 into multiple sections. It is divided into sections (the number of divisions is n), and for each section, the impedance on the high frequency side is calculated using the traveling wave power Pf and the reflected wave power Pr on the high frequency (source power supply 10) side. Further, the frequency setting calculation unit 303 calculates the frequency setting value for each section based on the impedance on the high frequency side of each section. Then, the frequency setting calculation unit 303 sets the frequency setting values for each section (1 to n) into one set and supplies it to the source power supply 10 on the high frequency side.

Matching calculation section 1_304, matching calculation section 2_305, high frequency side matching network 306, low frequency side matching network 307, and output sensor 308 included in matching box 30 have the same configuration as the conventional matching box. For example, the high frequency side matching network 306 and the low frequency side matching network 307 are configured with variable capacitors and variable inductors. Further, the matching calculation unit 1_304 and the matching calculation unit 2_305 are configured by a motor and a control unit (processor) that change the capacitance of the variable capacitor and the inductance of the variable inductor included in the matching network. Further, the output sensor 308 detects the traveling wave power Pf and the reflected wave power Pr on the load side.

Note that the operation of the power supply system 1 will be described in more detail later.

&lt;S-parameters and T-parameters&gt; The matching box 30 holds in a memory (not shown) a three-dimensional S-parameter table that provides S-parameters corresponding to the position and frequency (deviation amount from the fundamental frequency) of the variable capacitor. Note that the S-parameters do not necessarily need to be held in a table format, and may be in any format as long as there is a one-to-one correspondence between the variable capacitor value and frequency shift and the S-parameter.

FIG. 2 is a diagram showing a configuration example of a three-dimensional S-parameter table that provides S-parameters corresponding to the position and frequency (frequency deviation amount) of a variable capacitor. Table 1 shows a position-characteristic parameter table, and Table 2 shows a frequency (deviation amount from the fundamental frequency)-characteristic parameter. The granularity of each table is just an example, and the table may be configured with even finer steps. Alternatively, an interpolation calculation may be performed on the S parameters to use the optimum S parameters. As is well known, the S-parameter (Scattering Parameter) here refers to, for example, the input terminal and output terminal of a predetermined 4-terminal circuit network (also referred to as 2-terminal pair circuit network) in relation to the position of a variable capacitor. It shows the transmission characteristics in a 4-terminal network when a high-frequency signal is input to the terminal with a line of characteristic impedance (for example, 50Ω), and the voltage reflection coefficient on the input side, the transfer coefficient of forward voltage, and the reverse direction It is expressed as a matrix composed of each element of a voltage transfer coefficient and an output-side voltage reflection coefficient. Here, matching box 30 is treated as a four-terminal network, and S parameters in matching box 30 are calculated.

As shown in Table 1, the current S-parameter can be obtained from the combination of the current values of variable capacitors C1 and C2. Then fix C1 and C2 and its S-parameter A_mnS parameter corresponding to the amount of frequency deviation (the amount of deviation between the frequency obtained from the traveling wave power Pf and the reflected wave power Pr in the above interval k (k = an integer from 1 to n) and the fundamental frequency (e.g. 40MHz)) (A_mn0From A_mn6) can be found. For example, if (C1,C2)=(40,60), the S parameter is A₃₂becomes. At this time, if the deviation amount between the frequency of the actually calculated traveling wave power Pf and the fundamental frequency 40MHz is 0.6 (Hz), from Table 2, the corresponding S parameter A₃₂₅is obtained. The S-parameters corresponding to this frequency shift amount are similar to the S-parameters related to the position of the variable capacitor mentioned above, as well as the voltage reflection coefficient on the input side, the transfer coefficient of forward voltage, the transfer coefficient of reverse voltage, and the voltage on the output side. It is expressed as a matrix composed of each element of the reflection coefficient.

For example, in the S parameter of a 4-terminal network, the voltage reflection coefficient on the input side is₁₁, the forward voltage transfer coefficient is S₂₁, the reverse voltage transfer coefficient is S₁₂, the voltage reflection coefficient on the output side is S₂₂Then, the T parameter (Transmission Parameter) can be obtained by converting the S parameter as shown in equation (1). In general, for example, in a four-terminal circuit network, it is considered convenient to use S parameters when measuring the transmission characteristics, and it is convenient to use T parameters when performing calculations.

<math num="1"><img file="JP7474591B2_D0001.tif" /></math>

&lt;Details of frequency matching calculation process in power supply system 1&gt; FIGS. 3A and 3B are flowcharts for explaining in detail the frequency matching calculation process by power supply system 1 according to the present embodiment. Note that the frequency matching calculation process can be controlled to start, for example, when the reflection coefficient of the source power supply (high frequency side) 10 becomes equal to or higher than a predetermined value. In addition, the details (basic technical idea) of calculation of S parameters, T parameters, Γout, Γin, etc., which will be explained below, are described in detail in JP-A No. 2006-166412 and JP-A No. 2014-72806. has been done.

(i) Step 3001 When the power supply system 1 is activated, the source power supply 10 starts supplying power to the matching box 30 side. Then, the sine wave synchronization signal generating section 101 of the source power supply 10 supplies a sine wave synchronization signal to the bias power supply 20. This sine wave synchronization signal (synchronous high frequency signal) is a sine wave signal having an output frequency that the bias power supply 20 should output.

(ii) Step 3002 The sine wave synchronization signal receiving unit 201 of the bias power supply 20 receives the sine wave synchronization signal from the source power supply 10, and acquires information on the frequency (eg, 400 kHz) and phase of this sine wave synchronization signal. An oscillator (not shown) supplies RF output (travelling wave power) to the matching box 30 in synchronization with the sine wave synchronization signal based on information on the frequency and phase of the sine wave synchronization signal. At this time, the output frequency of the source power supply 10 is fixed to a specified frequency (for example, 40.68MHz).

Sensor 1_301 of matching box 30 detects traveling wave power Pf supplied from source power supply 10 and reflected wave power Pr from plasma load 40, or input voltage Vpf and input current Ipf at the input end of matching box 30. In addition, the sensor 2_302 of the matching box 30 receives the traveling wave power Pf (including phase information) supplied from the bias power supply 20 and the reflected wave power Pr from the plasma load 40, or the input voltage at the input end of the matching box 30. Detects Vpf and input current Ipf.

(iii) Step 3003 The matching calculation unit 304 of the matching box 30 acquires the Pf, Pr (or Vpf, Ipf) signals detected by the sensor 1_301, and extracts only the output frequency component of the bias power supply using a bandpass filter. do. The input reflection coefficient Γin is determined using the extracted data.

(iv) Step 3004 The matching calculation unit 304 of the matching box 30 reads out the position-characteristic parameters (Table 1) from the memory (not shown), refers to them, and uses the obtained capacitance values C1 and C2 of the variable capacitors of the high-frequency side matching network 306. Get the corresponding S-parameters.

(v) Step 3005 The matching calculation unit 304 calculates the output reflection coefficient Γout (the reflection coefficient at the output end 30b of the matching device 30) using the S parameter acquired in step 3004 and the input reflection coefficient Γin. More specifically, the T parameter is calculated from the S parameter using Equation 1 above (note that the T parameter may be calculated in advance and held in the memory as a table). Then, the traveling wave voltage Vfo and reflected wave voltage Vro on the load 40 side are calculated from the traveling wave voltage Vfi, reflected wave voltage Vri, and T parameter at the high frequency side input terminal 30a of the matching box 30 (see equation (2)) .

<math num="2"><img file="JP7474591B2_D0002.tif" /></math>

The reflection coefficient Γout at the output end 30b is obtained by calculating Vro/Vfo. Furthermore, the traveling wave voltage Vfi and the reflected wave voltage Vri at the input end 30a of the matching box 30 are derived from equation (2) as shown in equation (3).

<math num="3"><img file="JP7474591B2_D0003.tif" /></math>

The reflection coefficient Γin at the input end 30a (the reflection coefficient Γin at the input end 30a of the matching device 30) is obtained by calculating Vri/Vfi.

(vi) Step 3006 The matching calculation unit 304 fixes the variable capacitance value at the current position, and uses the output reflection coefficient Γout and the position-characteristic parameter table (for example, position-T parameter) to create a virtual input reflection coefficient Γin'. seek. The value of the variable capacitor (positions C1 and C2) that minimizes this input reflection coefficient Γin' is determined. In other words, the matching calculation unit 304 calculates the S parameter by A in Table 1, for example.₀₀From A₅₅The T parameter corresponding to is calculated (Equation (1)), and each T parameter is applied to the above Equation (3) to obtain the reflection coefficient Γin. Then, the matching calculation unit 304 determines the variable capacitor position (C1min, C2min) that contributes to the minimum reflection coefficient Γin_min from among the plurality of reflection coefficients Γin corresponding to each variable capacitor position (C1, C2).

(vii) Step 3007 The matching calculation unit 304 moves the variable capacitor to the variable capacitor position (C1min, C2min) determined in step 3006. After the movement, the process of step 3003 is executed, and if the input reflection coefficient Γin is equal to or greater than the threshold value Γth indicating completion of matching, steps 3004 to 3006 are repeated. If the input reflection coefficient Γin is less than the threshold value Γth, the position of the variable capacitor is fixed and step 3008 is executed.

(viii) Step 3008 The frequency setting calculation unit 303 (hereinafter referred to as the frequency setting calculation unit 303) of the matching box 30 converts the traveling wave power Pf supplied from the source power supply 10 for the sine wave synchronization signal and the corresponding Divide the reflected wave power Pr into multiple sections (n divisions: n is an integer; for example, 10 divisions). Note that FIG. 4 shows a state in which the traveling wave power Pf supplied from the source power supply 10 for one cycle and the corresponding reflected wave power Pr are divided into multiple sections (sections 1 to n). .

Then, the processes from step 3008 to step 3010 are repeated for each section (k=1 to n) obtained by division.

(ix) Step 3009 The frequency setting calculation unit 303 calculates Γout_k (matching unit 30 (reflection coefficient at the output end 30b) is calculated. More specifically, similar to the process in step 3005, the T parameter is calculated from the S parameter using Equation 1 above (note that the T parameter may be calculated in advance and stored in the memory as a table. ). Furthermore, the traveling wave voltage Vfo and reflected wave voltage Vro on the load 40 side are calculated from the traveling wave voltage Vfi, reflected wave voltage Vri, and T parameter at the high frequency side input terminal 30a of the matching box 30 (see formula (2)) . Then, the reflection coefficient Γout_k at the output end 30b is obtained by calculating Vro/Vfo.

(x) Step 3010 The frequency setting calculation unit 303 refers to the frequency-characteristic parameters (Table 2) and selects the S parameter corresponding to each frequency deviation amount (for example, the S parameter corresponding to the frequency deviation amount -0.9 to 0.9). At the same time, calculate the T parameter from the S parameter based on Equation 1. Then, the frequency setting calculation unit 303 calculates the virtual input reflection coefficient Γin_k' at the input end 30a of the matching box 30 based on the T parameter corresponding to the calculated frequency shift amount and the output reflection coefficient Γout_k, and calculates Γin_k'. Determine the frequency shift amount (interval k) corresponding to the T parameter to be minimized. Similarly to the position-characteristic parameter table, if the frequency-characteristic parameter table has coarse granularity, as shown in Japanese Patent Application Laid-Open No. 2014-72806, appropriate S-parameters are obtained using interpolation calculations, and A corresponding T parameter may be adopted.

(xi) Step 3011 The frequency setting calculation unit 303 calculates the frequency setting value for one cycle of the bias power supply operating cycle (400kHz) from the frequency deviation amount determined for each divided section 1 to k (for example, 40MHz + frequency deviation amount). Determine and transmit to the source power supply on the high frequency side (e.g. 40MHz power supply)10. Since the frequency setting values to be transmitted are frequency-matched values in each section, if power is supplied from the source power supply 10 using these frequency setting values, the reflection coefficient can be kept small and the influence of IMD can be reduced. You will be able to do this.

(xii) Step 3012 The source power supply 10 generates power for each divided section (1 to n) based on the frequency setting value provided from the matching box 30, and provides this to the matching box 30 side. The frequency setting value will continue to be used by the source power supply 10 unless it is updated by the matching box 30 and sent to the source power supply 10. Whether or not to update the frequency setting value is determined, for example, when the frequency setting calculation unit 303 of the matching box 30 determines whether the reflection coefficient obtained from the traveling wave power Pf and reflected wave power Pr on the high frequency side (source power supply 10) exceeds a predetermined value. This can be determined by monitoring whether the

(xiii) Others In addition, the frequency setting calculation unit 303 detects the frequency of the high frequency power supply in section k from the voltage of the traveling wave power Pf supplied from the source power supply 10, and sets the detected high frequency as the fundamental frequency (e.g. 40MHz). The amount of deviation from the frequency of the power source can be calculated. At this time, if the frequency shift amount is less than a predetermined threshold, the process of determining the frequency setting value in each divided section (1 to n) and transmitting it to the source power supply 10 may not be executed.

&lt;Timing Chart of Frequency Setting Calculation Process&gt; FIG. 4 is a timing chart of the process (frequency setting calculation process) for obtaining frequency-matched frequency setting values described in FIGS. 3A and B, according to the present embodiment. Note that in FIG. 4, the delay in the operation of the source power supply 10 on the high frequency side is not taken into account.

In FIG. 4, during period T1 (=period for one operation cycle (400kHz) of bias power supply 20: power supply cycle by source power supply 10), matching box 30 (frequency setting calculation unit 303) In addition to calculating the phase and reflection coefficient Γ of 10), the period T1 corresponding to one cycle of power supply is divided into n. Then, in the next period T2 after the end of period T1 (for example, it changes depending on the value of the number of divisions n), the matching unit 30 performs a frequency matching calculation (steps 3004 to 3010 in FIGS. 3A and 3B). process). For example, if the power supply cycle (eg, 400 kHz) by the source power supply 10 is divided into n, and if the frequency matching calculation in each section takes 1 to 2 μs, the period T2 will be n to 2 n μs. In period T3 after period T2, the frequency setting value of each section obtained by the frequency matching calculation and information on the divided sections are transmitted from the matching box 30 to the source power supply 10 on the high frequency side (DDS (Digital Direct Synthesizer) settings). Then, in period T4, source power supply 10 starts supplying power in each divided section using the frequency setting value received from matching box 30. Note that the matching box 30 can perform power transmission control (power transmission stop control) so as not to send the power supplied from the source power supply 10 to the plasma load 40 side during the period T1 to T3.

Furthermore, during the period T4, the matching box 30 monitors the operation of the source power supply 10 to determine whether the frequency setting value should be updated while calculating the phase and reflection coefficient on the high frequency side. When the reflection coefficient becomes larger than the predetermined threshold, the matching unit 30 performs frequency matching calculation in each divided section n again and determines a new frequency setting value.

&lt;Modification&gt; In the embodiment described above, synchronization is made with the phase of the traveling wave power Pf on the low frequency (bias power supply 20) side, and one cycle of the operating frequency of the bias power supply 20 (for example, 400 kHz: power supply cycle of the source power supply 10) Divide the output of the source power supply 10 into multiple sections (number of divisions n), and calculate the impedance on the high frequency side for each section using the forward wave power Pf and reflected wave power Pr on the high frequency (source power supply 10) side. However, phase information may be extracted from the output of the output sensor 308, and the impedance on the high frequency (source power supply 10) side may be calculated based on it. In fact, the output given to the plasma load 40 (with a supply cycle of 400 kHz) is supplied from the output sensor 308. Therefore, it is possible to obtain an appropriate impedance by matching the phase of the output of the output sensor 308. In other words, changes in impedance on the high frequency side (source power supply: e.g. 40MHz frequency output) appear as changes in plasma load, so detecting the phase closer to the plasma load is more sensitive to changes. This is because it can be done. Note that the output from the output sensor reflects the phase on the low frequency (bias power supply 20) side.

&lt;Summary&gt; (i) According to the present embodiment, the high frequency power supply system 1 includes a bias power supply that outputs bias power (RF output) at a low frequency (400 kHz as an example) and a source power supply at a high frequency (40 MHz as an example). The device includes a source power source that outputs (RF output), and a matching device that includes an impedance matching circuit that obtains bias power and source power and matches the impedance of the source power source and the impedance of the load side. In this embodiment, the source power supply supplies the bias power supply with a sine wave synchronization signal that includes information on the output frequency (for example, 400kHz) that the bias power supply should output, and the bias power supply supplies the bias power supply with Outputs bias power at a frequency corresponding to the output frequency (high frequency side power supply cycle, that is, 400kHz). The matching box divides the traveling wave power of one cycle (400 kHz) of the bias power from the source power supply and the reflected wave power to the source power supply into multiple sections, and performs frequency matching for each of the multiple sections. Processing is performed to determine the frequency setting value for each section by performing calculations, and processing for transmitting the frequency setting value for each section to the source power source. Then, the source power supply outputs bias power in the plurality of sections according to the frequency setting values for the plurality of sections transmitted from the matching box. By doing so, it becomes possible to reduce the reflected wave power Pr or the power reflection coefficient generated by the IMD.

Once determined, the frequency setting values (a set of setting values set for each of the plurality of sections 1 to n) are continuously used until updated by the matching device. The necessity of updating the frequency setting value is determined by whether or not the reflected wave power has increased due to the traveling wave power supplied from the source power supply using the current frequency setting value in the matching box, and the reflection coefficient has exceeded a predetermined value. determined by If the reflection coefficient exceeds a predetermined value, the frequency matching calculation is performed again and a new frequency setting value (a set of setting values set for each of the plurality of sections 1 to n) is determined. Ru. In this way, the once determined frequency setting value can be used continuously for a while, so it is possible to avoid a situation where the power supply has to be interrupted. Furthermore, if the influence of IMD is detected (if an increase in the reflection coefficient is observed), the frequency setting value is immediately updated, so power can always be supplied to the plasma load in an optimal state.

(ii) The matching box contains S-parameter information (Table 1 and 2), and determine the frequency setting values for the plurality of sections by specifying the frequency shift amount that minimizes the reflection coefficient on the source power side in each of the plurality of sections based on the S parameter.

More specifically, the process of determining the frequency setting values for the plurality of sections is based on the fundamental frequency (for example, 40MHz) of the source power supply 10 and the S parameters (Table 1) determined by the positions of the plurality of variable capacitors. The process of calculating the reflection coefficient on the output side in each of multiple sections, the process of calculating the reflection coefficient on the input side while changing the amount of frequency deviation by referring to the S-parameter information (Table 2), and the process of calculating the reflection coefficient on the input side while changing the amount of frequency deviation. and determining an optimal frequency shift amount that minimizes the reflection coefficient of. By applying this optimal frequency shift amount to the fundamental frequency (for example, 40 MHz), frequency setting values for each of the plurality of sections are determined.

(iii) Basically, the impedance is calculated according to the phase detected by the input side sensor (low frequency side sensor 2_302), but the impedance is calculated according to the phase of the output side sensor (output sensor 308). may be calculated. By doing so, it becomes possible to calculate a more appropriate impedance (on the high frequency side).

(iv) The functions of this embodiment can also be realized by software program codes. In this case, a storage medium recording a program code is provided to a system or device, and a 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 functions of the embodiments described above, and the program code itself and the storage medium storing it constitute the present disclosure. Storage media for supplying such program codes include, for example, flexible disks, CD-ROMs, DVD-ROMs, hard disks, optical disks, magneto-optical disks, CD-Rs, magnetic tapes, nonvolatile memory cards, and ROMs. etc. are used.

Further, based on the instructions of the program code, an OS (operating system) running on the computer performs some or all of the actual processing, so that the functions of the above-described embodiments are realized by the processing. You can. Furthermore, after the program code read from the storage medium is written into the computer's memory, the computer's CPU performs some or all of the actual processing based on the instructions of the program code. The functions of the embodiments described above may be realized by the following.

Furthermore, by distributing the software program code that realizes the functions of the embodiments via a network, it can be distributed to a storage medium such as a hard disk or memory of a system or device, or a storage medium such as a CD-RW or CD-R. The computer (or CPU or MPU) of the system or device may read and execute the program code stored in the storage means or storage medium when used.

The processes and techniques described herein are not inherently related to any particular apparatus. Also, various types of general purpose devices can be used in accordance with the descriptions of this disclosure. It should be noted that there may be cases where it is beneficial to construct a dedicated device to implement the techniques of this disclosure.

Various inventions can be formed by appropriately combining the plurality of components disclosed in this embodiment. For example, some components may be deleted from all the components shown in this embodiment. Furthermore, components of different embodiments may be combined as appropriate. Although the presently disclosed technology has been described in connection with specific example embodiments, these are for illustrative purposes and not to limit the presently disclosed technology. Those skilled in the art will appreciate that there are numerous combinations of hardware, software, and firmware that are suitable for implementing the techniques of this disclosure. For example, the written software can be implemented in a wide variety of programming or scripting languages, such as assembler, C/C++, perl, shell, PHP, Java(R), and the like.

Furthermore, in the embodiments described above, the control lines and information lines are shown to be necessary for explanation, and not all control lines and information lines are necessarily shown in the product. All configurations may be interconnected.

1 Power supply system (high frequency power system)

Ten Source (HF) power supply

20 bias power supply

30 matching box

40 plasma load

101 Sine wave synchronous signal generator

201 Sine wave synchronous signal receiver

301 sensor 1

302 sensor 2

303 Frequency setting calculation section

304 Matching calculation unit 1

305 Matching calculation section 2

306 High frequency matching network

307 Low frequency matching network

308 output sensor