Impedance matcher and high-frequency power supply system

Abstract

To provide a technique to calculate an impedance change (locus) in which a reflection wave by IMD is considered.SOLUTION: An impedance matching box, which performs impedance matching between the source power supply 10 side and the load side, includes: a detector unit 311 which detects traveling wave power supplied from the source power supply 10 and reflection wave power from the load, so as to output a traveling wave voltage, which is a component of the traveling wave power, and a reflection wave voltage which is a component of the reflection wave power; an impedance information output unit 312 which calculates impedance from the traveling wave voltage and the reflection wave voltage; and a matching unit 313 which performs matching calculation based on the impedance value supplied from the impedance information output unit 312. The impedance information output unit 312 calculates the impedance value by complexing the traveling wave voltage and the reflection wave voltage, respectively, to generate the impedance locus using the impedance value.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an impedance matcher and a high-frequency power supply system.

Background Art

[0002] In the field of semiconductor manufacturing, with the miniaturization and high functionality of electronic devices, high-density mounting is required. The connection of elements to a mounting substrate has been miniaturized, and more reliable mounting is needed.

[0003] One method for ensuring the reliability of mounting is a surface modification method using plasma. For example, when a substrate to be processed is subjected to plasma treatment, contamination due to organic substances adhering to the surface of the substrate can be removed, the bonding strength of wire bonding can be improved, the wettability can be improved, and the adhesion between the substrate and the encapsulating resin can be improved. In order to perform such plasma treatment, it is necessary to connect a power supply device to a plasma reactor device that serves as a load.

[0004] In plasma processing, a method of inputting high-frequency power having different fundamental frequencies (frequencies of fundamental waves) from a plurality of power supplies to a load is used. For example, when supplying a first high-frequency power to a load by outputting a first high-frequency voltage having a first fundamental frequency (for example, 40.68 MHz) from a first power supply and supplying a second high-frequency power to the load by outputting a second high-frequency voltage having a second fundamental frequency (for example, 400 kHz) (the first fundamental frequency > the second fundamental frequency) from a second power supply, intermodulation distortion (hereinafter, IMD) occurs in the output on the first power supply side where the fundamental frequency is high, and a phenomenon occurs in which the reflected wave power fluctuates according to the period of the second fundamental frequency.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] Conventional matching devices calculate impedance only at the first fundamental frequency through a band-pass filter from a detection unit and perform matching operations with IMD components removed. For this reason, in terms of power including IMD components, reflected wave power corresponding to the second fundamental frequency is generated, and power cannot be efficiently supplied to a load (for example, a plasma reactor device). Therefore, as is also described in the prior art documents, a method for reducing reflected wave power by controlling the power supply frequency on the high-frequency side has been proposed. When implementing this frequency control, a method capable of sequentially calculating the impedance on the high-frequency side that varies in frequency at the second fundamental frequency is required. In view of such a situation, the present disclosure provides a technique for sequentially calculating impedance changes (trajectories) considering reflected waves due to IMD. Means for Solving the Problems

[0007] In order to solve the above problems, the present disclosure is disposed between a first power supply that supplies first high-frequency power to a load by outputting a first high-frequency voltage having a first fundamental frequency and the load, and is an impedance matching device that performs impedance matching between the first power supply side and the load side, and includes a detection unit that acquires information regarding the first high-frequency power, an impedance information output unit that calculates an impedance value based on the information acquired by the detection unit, and a matching unit that performs a matching operation based on the impedance value supplied from the impedance information output unit. The impedance information output unit provides an impedance matching device that generates an impedance trajectory using the impedance value.

[0008] Further features related to the present disclosure will become apparent from the description of this specification and the accompanying drawings. Also, aspects of the present disclosure are achieved and realized by elements and combinations of various elements, as well as aspects of the following detailed description and the appended claims. It should be understood that the description in this specification is merely a typical example and does not limit the claims or the scope of application in any way.

Advantages of the Invention

[0009] According to the technology of the present disclosure, it becomes possible to calculate the impedance change (locus) considering the reflected wave by the IMD.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may sometimes be denoted by the same reference numerals. Note that the accompanying drawings show specific embodiments and implementation examples in accordance with the principles of the present disclosure, but these are for the purpose of understanding the present disclosure and are by no means used for interpreting the present disclosure in a limiting manner.

[0012] In this embodiment, although the description is made in sufficient detail for those skilled in the art to implement the present disclosure, other implementation forms are also possible, and it is necessary to understand that configuration and structural changes and replacement of various elements can be made without departing from the scope and spirit of the technical idea of the present disclosure. Therefore, the following description should not be construed as being limited thereto.

[0013] Furthermore, the embodiments of the present disclosure may be implemented by software running on a general-purpose computer, or may be implemented by dedicated hardware or a combination of software and hardware.

[0014] <Configuration example of power supply system 1> FIG. 1 is a diagram showing a state in which a plasma load 40 is connected to a power supply system 1 (also referred to as a high-frequency power supply system) according to this embodiment. The power supply system 1 includes a source power supply 10 (first power supply) that supplies first high-frequency power to a load by outputting a first high-frequency voltage having a first fundamental frequency, and a bias power supply 20 (second power supply) that supplies second high-frequency power to the load by outputting a second high-frequency voltage having a second fundamental frequency lower than the first fundamental frequency, and a matching unit (also referred to as an impedance conversion device) 30 to which outputs are supplied from the source power supply 10 and the bias power supply 20 respectively, and that performs impedance matching between the source power supply 10 and the bias power supply 20 side and the plasma load 40 side. The system supplies a traveling wave (source power) output from the source power supply 10 and a traveling wave (bias power) output from the bias power supply 20 to the plasma load 40 by, for example, superimposing them.

[0015] In this embodiment, the fundamental frequency (the frequency of the fundamental wave, also referred to as the output frequency) of the high-frequency voltage output from the source power supply 10 is 40.68 MHz, and the fundamental frequency of the high-frequency voltage output from the bias power supply 20 is 400 kHz. However, the fundamental frequency of the source power supply 10 is not limited to 40.68 MHz, and it may be a frequency in the industrial RF band (RF: Radio Frequency) such as 13.56 MHz or 27.12 MHz. Also, the fundamental frequency of the bias power supply 20 is not limited to 400 kHz, and it may be other frequencies. Also, the fundamental frequency of the source power supply 10 is set as the HF frequency, and the fundamental frequency of the bias power supply 20 is set as the LF frequency. Also, the fundamental period (the period of the fundamental wave: 1 / fundamental frequency) of the source power supply 10 is set as the HF period, and the fundamental period (1 / fundamental frequency) of the bias power supply 20 is set as the LF period.

[0016] The matcher 30 includes a first matcher 310 corresponding to the source power supply 10 and a second matcher 320 corresponding to the bias power supply 20. The first matcher 310 is disposed between the source power supply 10 and the plasma load 40 and performs impedance matching between the source power supply 10 side and the plasma load 40 side. The second matcher 320 is disposed between the bias power supply 20 and the plasma load 40 and performs impedance matching between the bias power supply 20 side and the plasma load 40 side.

[0017] The first matcher 310 includes a detection unit 311 that detects the forward wave (power) Pf and the reflected wave (power) Pr and outputs the forward wave voltage (component) Vf and the reflected wave voltage (component) Vr, an impedance information output unit 312 that acquires the forward wave voltage (component) Vf and the reflected wave voltage (component) Vr from the detection unit 311, calculates the impedance value, generates and outputs an impedance locus, and outputs the impedance value, and a matching unit 313 that acquires the impedance value from the impedance information output unit 312 and performs impedance matching between the source power supply 10 side and the plasma load 40 side. The second integrator 320 includes a detection unit 311, an impedance information output unit 312, and an integration unit 313. Although the corresponding frequencies and the like are different, since they have the same configuration as the first integrator 310, the description thereof is omitted.

[0018] <Internal configuration example of impedance information output unit 312> FIG. 2 is a diagram showing an internal configuration example of the impedance information output unit 312 according to the present embodiment. The impedance information output unit 312 includes a DDS (Direct Digital Synthesizer) 3021 that generates (oscillates) and outputs signals (cos component and sin component) at the fundamental frequency f (for example, 40.68 MHz) of the source power supply 10 (HF power supply), multipliers 3022 to 3025, an averaging processing unit 3026, an impedance calculation unit 3027, and an impedance locus output unit 3028.

[0019] The multiplier 3022 multiplies the incident wave voltage Vf from the detection unit 311 by the oscillation output (cos(2πf·ts·k)) of the DDS 3021, and the multiplier 3023 multiplies the incident wave voltage Vf from the detection unit 311 by the oscillation output (sin(2πf·ts·k)) of the DDS 3021. The multiplier 3024 multiplies the reflected wave voltage Vr from the detection unit 311 by the oscillation output (cos(2πf·ts·k)) of the DDS 3021, and the multiplier 3025 multiplies the reflected wave voltage Vr from the detection unit 311 by the oscillation output (sin(2πf·ts·k)) of the DDS 3021. By the DDS 3021 and the multipliers 3022 to 3025, the detection values (incident wave voltage Vf and reflected wave voltage Vr) of the detection unit 311 are made complex. Here, f (Hz) represents the HF frequency, ts represents the sample period (the operation period of the DDS 3021 on the source power supply 10 side), and k represents the number of samples.

[0020] The averaging processing unit 3026 averages the values of the complex incident wave voltage and reflected wave voltage at the period of the fundamental frequency f of the source power supply 10, and outputs averaged outputs Vf·sinθ, Vf·cosθ, Vr·sinθ, and Vr·cosθ. Here, θ = 2πf·ts·k.

[0021] The impedance calculation unit 3027 calculates the impedance from the averaged outputs Vf·sinθ, Vf·cosθ, Vr·sinθ, and Vr·cosθ, converts this into the reflection coefficient (vector components U, V), and supplies it to the matching unit 313 and the impedance locus output unit 3028, respectively. More specifically, the impedance calculation unit 3027 obtains Vf from Vf·sinθ and Vf·cosθ, obtains Vr from Vr·sinθ and Vr·cosθ, and calculates the impedance value from Vr / Vf.

[0022] The impedance locus output unit 3028 obtains and outputs the impedance locus based on the reflection coefficient (vector components U, V) acquired from the impedance calculation unit 3027. The output impedance locus is displayed, for example, on the display screen of a management computer (not shown).

[0023] <Processing in the impedance information output unit 312> FIG. 3 is a flowchart for explaining the operation of the impedance information output unit 312 (processing from obtaining the traveling wave voltage Vf and the reflected wave voltage Vr to outputting the impedance locus).

[0024] (i) Step 301 The impedance information output unit 312 acquires the voltage component Vf (traveling wave voltage) of the traveling wave power Pf and the voltage component Vr (reflected wave voltage) of the reflected wave power Pr from the detection unit 311. For example, the traveling wave voltage Vf and the reflected wave voltage Vr input from the detection unit 311 to the impedance information output unit 312 have waveforms as shown in FIG. 4.

[0025] (ii) Step 302 The impedance information output unit 312 generates (oscillates) and outputs signals (cosine component and sine component) at the HF frequency f (for example, 40.68 MHz) from the DDS 3021. Then, the multiplier 3022 multiplies the traveling wave voltage Vf from the detector 311 by the oscillation output (cos(2πf·ts·k)) of the DDS 3021, and the multiplier 3023 multiplies the traveling wave voltage Vf from the detector 311 by the oscillation output (sin(2πf·ts·k)) of the DDS 3021. The multiplier 3024 multiplies the reflected wave voltage Vr from the detector 311 by the oscillation output (cos(2πf·ts·k)) of the DDS 3021, and the multiplier 3025 multiplies the reflected wave voltage Vr from the detector 311 by the oscillation output (sin(2πf·ts·k)) of the DDS 3021. By the DDS 3021 and the multipliers 3022 to 3025, the detected values (traveling wave voltage Vf and reflected wave voltage Vr) of the detector 311 are made complex. That is, the DDS 3021 and the multipliers 3022 to 3025 constitute a complex filter. By the complex filter, Vf and Vr become Vf = Vf{cos(2πf·ts·k) - j·sin(2πf·ts·k)}, Vr = Vr{cos(2πf·ts·k) - j·sin(2πf·ts·k)}.

[0026] (iii) Step 303 The averaging processing unit 3026 of the impedance information output unit 312 acquires the complexified traveling wave voltage and reflected wave voltage that are the outputs of the multipliers 3022 to 3025, and averages them over the HF period. Specifically, the averaging processing unit 3026 averages the complexified Vf and Vr over the HF period for each DDS operation period (1 / DDS operation frequency (for example, 100 MHz)).

[0027] (iv) Step 304 The impedance calculation unit 3027 of the impedance information output unit 312 calculates an impedance value using the averaged incident wave voltages (Vf·cosθ and Vf·sinθ) and the averaged reflected wave voltages (Vr·cosθ and Vr·sinθ). Specifically, the impedance calculation unit 3027 obtains the vector of the reflection coefficient (Vr / Vf) using the voltage values averaged in the HF period by the averaging processing unit 3026. By this calculation, the impedance value for each HF period is calculated.

[0028] (v) Step 305 The impedance locus output unit 3028 of the impedance information output unit 312 acquires and outputs the vector of the reflection coefficient (vector (U, V)) obtained by dividing the LF period (1 / 400 kHz) by the HF period (1 / 40.68 MHz). Specifically, it acquires the reflection coefficients (vectors) for ((1 / 400 kHz)÷(1 / 40.68 MHz)) and generates and outputs the impedance locus for one period of the LF frequency.

[0029] <Impedance Locus> FIG. 5 is a diagram showing the impedance locus for one period of the LF period when matching is achieved by a conventional detection method (detection of only the fundamental wave). Since it is in a matched state (reflection coefficients (u, v) = (0, 0)), the impedance in the conventional detection is near the center of the Smith chart, but the impedance locus spreads up to around an absolute value of the reflection coefficient of 0.8 at maximum, and reflected power is generated. Also, when vector-averaging each data (reflection coefficients (u, v)) of the impedance locus for one period of the LF period, it becomes near the matched state (reflection coefficients (u, v) = (0, 0)), so an average impedance equivalent to the conventional detection method can be calculated.

[0030] <Impedance during Frequency Control> In the conventional detection method, since the detection is performed through a narrow-band band-pass filter, when frequency control is performed, the configuration is such that the impedance cannot be correctly calculated. In the method of obtaining the impedance locus, since there is no band-pass filter, as long as it is within a certain range, the impedance locus can be calculated even if the frequency is other than the fundamental wave. Further, by vector-averaging this impedance locus, the average impedance during frequency control can be calculated.

[0031] By generating and outputting (presenting) the impedance locus as described above, the operator (user) can use it for impedance matching when performing frequency control.

[0032] <Summary> (i) According to the present embodiment, in the impedance information output unit 312 in the matcher 30 (the first matcher 310), the incident wave voltage and the reflected wave voltage are each complexified to calculate an impedance value, and an impedance locus is generated using the impedance value. Specifically, the impedance calculation unit 3027 averages the complexified incident wave voltage and reflected wave voltage over the HF period (the fundamental period of the source power supply 10), and calculates an impedance value using the averaged and complexified incident wave voltage and reflected wave voltage. Then, since the reflection coefficient vectors corresponding to the impedance values are acquired for the number of (1 / 400 kHz)÷(1 / 40.68 MHz) of the LF period, an impedance locus for one period of the LF frequency can be generated. Thereby, a change in impedance (impedance locus) considering IMD (reflected wave component) can be obtained. The operator can use such an impedance locus for impedance matching when performing frequency control.

[0033] In addition, the impedance information output unit 312 according to the present embodiment generates and outputs an impedance locus in consideration of IMD regardless of whether the traveling wave power is frequency-controlled. However, when the traveling wave power is frequency-controlled in the high-frequency power supply (source power supply 10), the impedance is calculated from the reflected wave voltage corresponding to the voltage components (traveling wave voltage and reflected wave voltage) of the frequency-controlled power. Thereby, by obtaining and comparing the impedance loci before and after the frequency control, it is possible to determine whether the impedance matching is optimally performed, and the effect of the frequency control can be confirmed.

[0034] (ii) The functions of the present embodiment can also be realized by software program codes. In this case, a storage medium recording the program codes is provided to a system or device, and a computer (or CPU or MPU) of the system or device reads the program codes stored in the storage medium. In this case, the program codes themselves read from the storage medium realize the functions of the above-described embodiments, and the program codes themselves and the storage medium storing them constitute the present disclosure. As a storage medium for supplying such program codes, for example, a flexible disk, CD-ROM, DVD-ROM, hard disk, optical disk, magneto-optical disk, CD-R, magnetic tape, non-volatile memory card, ROM, etc. are used.

[0035] In addition, based on the instructions of the program codes, an OS (operating system) or the like running on the computer may perform part or all of the actual processing so that the functions of the above-described embodiments are realized by the processing. Further, after the program codes read from the storage medium are written into the memory on the computer, based on the instructions of the program codes, a CPU or the like of the computer may perform part or all of the actual processing so that the functions of the above-described embodiments are realized by the processing.

[0036] Furthermore, by distributing the program code of the software that realizes the functions of the embodiments via a network, it can be stored in a storage means such as a hard disk or memory of a system or device, or a storage medium such as a CD-RW or CD-R, and when in use, a computer (or CPU or MPU) of the system or device reads and executes the program code stored in the storage means or the storage medium.

[0037] The processes and techniques described herein are not inherently related to any particular device. Also, various types of general-purpose devices can be used in accordance with the description of this disclosure. It should be noted that it may be beneficial to construct a dedicated device in implementing the technology of this disclosure.

[0038] Appropriate combinations of the multiple components disclosed in this embodiment can form various inventions. For example, some components may be deleted from all the components shown in this embodiment. Furthermore, components from different embodiments may be appropriately combined. The technology of this disclosure has been described in relation to specific example embodiments, but these are for explanation purposes rather than to limit the technology of this disclosure. Those skilled in the art will understand that there are numerous combinations of hardware, software, and firmware suitable for implementing the technology of 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 (registered trademark), etc.

[0039] Furthermore, in the above-described embodiments, the control lines and information lines show those considered necessary for explanation, and not necessarily all control lines and information lines are shown on the product. All components may be interconnected.

Description of Reference Numerals

[0040] 1 Power supply system (high-frequency power supply system) 10 Source (HF) power supply 20 Bias power supply 30 Integrator 40 Plasma Load 311 Detection Unit 312 Impedance Information Output Unit 313 Integration Unit 3021 DDS 3022 to 3025 Multiplier 3026 Averaging Processing Unit 3027 Impedance Calculation Unit 3028 Impedance Locus Output Unit

Claims

1. An impedance matching device disposed between a first power supply that supplies first high-frequency power to a load by outputting a first high-frequency voltage having a first fundamental frequency and the load, for impedance matching between the first power supply side and the load side, comprising: a detection unit that acquires information regarding the first high-frequency power; an impedance information output unit that calculates an impedance value based on the information acquired by the detection unit; a matching unit that performs a matching operation based on the impedance value supplied from the impedance information output unit, wherein the impedance information output unit generates an impedance locus using the impedance value, the detection unit detects the incident wave power supplied from the first power supply and the reflected wave power from the load, and outputs an incident wave voltage that is a component of the incident wave power and a reflected wave voltage that is a component of the reflected wave power, the impedance information output unit complexifies the incident wave voltage and the reflected wave voltage, respectively, averages the complexified incident wave voltage and reflected wave voltage over the fundamental period of the first power supply, calculates the impedance value using the averaged and complexified incident wave voltage and reflected wave voltage, and generates the impedance locus with a reflection coefficient vector corresponding to the impedance value. An impedance matching device.

2. In claim 1, when supplying second high-frequency power to the load using a second power supply that outputs a second high-frequency voltage having a second fundamental frequency lower than the first fundamental frequency, the impedance information output unit uses a change in the reflection coefficient vector during a period corresponding to the fundamental period of the second high-frequency voltage as the impedance locus. An impedance matching device.

3. In claim 1 or 2, the incident wave power is frequency-controlled in the first power supply, and the impedance information output unit calculates the impedance value from an incident wave voltage corresponding to the frequency-controlled incident wave power and a reflected wave voltage corresponding to the reflected wave power that is reflected back after the frequency-controlled incident wave power is supplied to the load. An impedance matching device.

4. A high-frequency power supply system that provides high-frequency power to a connected load, comprising: a first power supply that outputs a first high-frequency voltage having a first fundamental frequency; A second power supply that outputs a second high-frequency voltage having a second fundamental frequency lower than the first fundamental frequency; The impedance matcher according to any one of claims 1 to 3; A high-frequency power supply system comprising the same.

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