Plasma processing device, RF system and plasma processing method

Abstract

A technology for stabilizing impedance matching operation is provided. A plasma processing device is provided. The plasma processing device comprises a chamber, an antenna disposed above the chamber, an RF generator connected to the antenna, a measuring instrument configured to detect RF reflection characteristics at a node between the antenna and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma ignition sequence.

Description

Technology Field

[0001] Exemplary embodiments of the present disclosure relate to a plasma processing apparatus, an RF system, and a plasma processing method. Background Technology

[0002] Patent Document 1 discloses a configuration in which an RF power supply for generating plasma and an antenna installed above the chamber are connected through a matching device. Prior art literature

[0003] Japanese Patent Publication No. 2020-12933 The problem to be solved

[0004] The present disclosure provides a technique for stabilizing the impedance matching operation. means of solving the problem

[0005] In one exemplary embodiment of the present disclosure, the apparatus comprises a chamber, an antenna disposed above the chamber, an RF generator connected to the antenna, a measuring instrument configured to detect RF reflection characteristics at a node between the antenna and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma ignition sequence, wherein the plasma ignition sequence comprises: (a1) controlling the RF generator to output a first modulated RF signal having a plurality of frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber; (a2) obtaining an RF reflection spectrum for each frequency corresponding to the first modulated RF signal from the analyzer; (a3) ​​determining an ignition frequency based on the RF reflection spectrum for each frequency obtained in (a2); and (a4) controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulation A plasma processing device is provided that includes an RF signal having a power level capable of generating plasma in a chamber. Effects of the invention

[0006] According to one exemplary embodiment of the present disclosure, a technique for stabilizing impedance matching operation can be provided. Brief explanation of the drawing

[0007] Figure 1 is a diagram illustrating an example of the configuration of a plasma processing system. Figure 2 is a diagram illustrating an example of the configuration of an inductively coupled plasma processing device. Figure 3 is a diagram showing an example of an RF system. Figure 4 is a diagram showing another example of an RF system. Figure 5 is a flowchart showing an example of the method (MT). Figure 6 is a diagram illustrating the modulated RF signal and RF reflection spectrum at each process of the method (MT). Figure 7 is a flowchart showing an example of process ST1. Figure 8 is a flowchart showing an example of process ST2. Figure 9 is a flowchart showing an example of process ST3. Specific details for implementing the invention

[0008] Hereinafter, each embodiment of the present disclosure will be described.

[0009] In one exemplary embodiment, the apparatus comprises a chamber, an antenna disposed above the chamber, an RF generator connected to the antenna, a measuring device configured to detect RF reflection characteristics at a node between the antenna and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma ignition sequence, wherein the plasma ignition sequence comprises: (a1) controlling the RF generator to output a first modulated RF signal having a plurality of frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that no plasma is generated in the chamber; (a2) obtaining an RF reflection spectrum for each frequency corresponding to the first modulated RF signal from the analyzer; (a3) ​​determining an ignition frequency based on the RF reflection spectrum for each frequency obtained in (a2); and (a4) controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal A plasma processing device is provided that includes a power level capable of generating plasma in a chamber.

[0010] In one exemplary embodiment, the center frequency of the second frequency band is the ignition frequency.

[0011] In one exemplary embodiment, the control unit is configured to execute an impedance matching sequence after a plasma ignition sequence, and the impedance matching sequence comprises: (b1) controlling an RF generator to output a modulated RF signal having a plurality of frequency components, wherein the modulated RF signal has a power level capable of generating plasma in a chamber; (b2) obtaining a frequency-specific RF reflection spectrum corresponding to the modulated RF signal from an analyzer; (b3) determining a target frequency at which the RF reflection spectrum is minimized based on the frequency-specific RF reflection spectrum obtained in (b2); and (b4) narrowing the frequency band of the modulated RF signal output from the RF generator while adjusting the center frequency of the frequency band to become the target frequency.

[0012] In one exemplary embodiment, the impedance matching sequence further includes (b5) repeating (b1) through (b4) until the frequency band of the modulated RF signal output from the RF generation unit becomes the target width.

[0013] In one exemplary embodiment, the control unit is configured to execute a plasma maintenance sequence for maintaining plasma in a chamber after a matching sequence, and the plasma maintenance sequence comprises: (c1) controlling an RF generator to output a third modulated RF signal having a plurality of frequency components and a fourth modulated RF signal having a plurality of frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber and the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal; (c2) acquiring an RF reflection spectrum for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal from an analyzer; (c3) determining a target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each frequency acquired in (c2); and (c4) setting the frequency band of the third modulated RF signal output from the RF generator such that the center frequency of the frequency band becomes the target frequency.

[0014] In one exemplary embodiment, the RF reflection characteristic is any one of (a) the ratio or ratio of the power of the propagating wave to the power of the reflected wave at the node [%], (b) the resistance component of the impedance [Ω], (c) the reflection coefficient, (d) the return loss [dB], and (e) the S parameter [dB].

[0015] In one exemplary embodiment, an impedance matching circuit connected between the chamber and the measuring instrument is further provided.

[0016] In one exemplary embodiment, an impedance matching circuit connected between an RF signal generator and a measuring instrument is further provided.

[0017] In one exemplary embodiment, the RF generation unit includes a waveform output unit configured to output a broadband RF signal having a plurality of superimposed frequency components, and a power amplifier configured to amplify the broadband RF signal and output a modulated RF signal including a plurality of frequency components.

[0018] In one exemplary embodiment, the RF signal generation unit comprises a waveform output unit configured to sequentially output sweep RF signals of different frequencies, and a modulated RF signal including a plurality of frequency components by sequentially amplifying the sweep RF signals.

[0019] In one exemplary embodiment, the power level at which plasma is not generated is less than 10W.

[0020] In one exemplary embodiment, the first frequency band has a bandwidth of less than 20% of the design frequency of the RF generation unit, and the second frequency band has a bandwidth of less than 10% of the design frequency.

[0021] In one exemplary embodiment, the target width is within the range of 0.1 to 1% of the design frequency of the RF generation unit.

[0022] In one exemplary embodiment, in (b5), the frequency band of the modulated RF signal is narrowed from 0.1 kHz to 500 kHz.

[0023] In one exemplary embodiment, the apparatus comprises a chamber, an antenna disposed above the chamber, an RF generator connected to the antenna, a measuring device configured to detect RF reflection characteristics at a node between the antenna and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma maintenance sequence for maintaining a plasma generated in the chamber, wherein the plasma maintenance sequence comprises: (c1) controlling the RF generator to output a third modulated RF signal having a plurality of frequency components and a fourth modulated RF signal having a plurality of frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber, and the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal; (c2) obtaining an RF reflection spectrum for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal from the analyzer; and (c3) based on the RF reflection spectrum for each frequency obtained in (c2), the RF reflection spectrum is minimized A plasma processing apparatus is provided that includes determining a target frequency and (c4) setting the frequency band of a third modulated RF signal output from an RF generation unit such that the center frequency of the frequency band becomes the target frequency.

[0024] In one exemplary embodiment, an RF system is provided comprising: an RF generator coupled to a chamber; a measuring device configured to detect RF reflection characteristics at a node between the chamber and the RF generator; an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics; and a control unit configured to execute a plasma ignition sequence, wherein the plasma ignition sequence comprises: (a1) controlling the RF generator to output a first modulated RF signal having a plurality of frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber; (a2) acquiring an RF reflection spectrum for each frequency of the first modulated RF signal from the analyzer; (a3) ​​determining an ignition frequency based on the RF reflection spectrum for each frequency acquired in (a2); and (a4) controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal has a power level capable of generating plasma in the chamber.

[0025] In one exemplary embodiment, a plasma processing method is provided, comprising: a process of outputting a first modulated RF signal having a plurality of frequency components in a first frequency band to a chamber, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber; a process of detecting RF reflection characteristics from the chamber; a process of acquiring an RF reflection spectrum for each frequency corresponding to the first modulated RF signal based on the acquired RF reflection characteristics; a process of determining an ignition frequency based on the acquired RF reflection spectrum for each frequency; and a process of outputting a second modulated RF signal having a plurality of frequency components in a second frequency band to a chamber, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal has a power level capable of generating plasma in the chamber.

[0026] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In addition, identical or similar elements in each drawing are given the same reference numerals, and redundant descriptions are omitted. Unless otherwise specifically stated, positional relationships such as up, down, left, and right are described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and actual ratios are not limited to the ratios depicted.

[0027] <Example of Plasma Processing System Configuration>

[0028] FIG. 1 is a drawing for explaining an example configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device (1) and a control unit (2). The plasma processing system is an example of a substrate processing system, and the plasma processing device (1) is an example of a substrate processing device. The plasma processing device (1) includes a plasma processing chamber (10), a substrate support unit (11), and a plasma generation unit (12). The plasma processing chamber (10) has a plasma processing space. Additionally, the plasma processing chamber (10) has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas discharge port for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit (20) described later, and the gas discharge port is connected to an exhaust system (40) described later. The substrate support unit (11) is disposed within the plasma processing space and has a substrate support surface for supporting a substrate.

[0029] The plasma generation unit (12) is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR), a helicon wave excited plasma (HWP), or a surface wave plasma (SWP). Additionally, various types of plasma generation units may be used, including an alternating current (AC) plasma generation unit and a direct current (DC) plasma generation unit. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency within the range of 100 kHz to 10 GHz. Accordingly, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency within the range of 100 kHz to 150 MHz.

[0030] The control unit (2) processes computer-executable commands to execute various processes described in the present disclosure on the plasma processing device (1). The control unit (2) may be configured to control each element of the plasma processing device (1) to execute the various processes described herein. In one embodiment, part or all of the control unit (2) may be included in the plasma processing device (1). The control unit (2) may include a processing unit (2a1), a memory unit (2a2), and a communication interface (2a3). The control unit (2) is realized, for example, by a computer (2a). The processing unit (2a1) may be configured to perform various control operations by reading a program from the memory unit (2a2) and executing the read program. This program may be stored in the memory unit (2a2) in advance, or may be acquired via a medium when necessary. The acquired program is stored in the memory unit (2a2) and is read from the memory unit (2a2) and executed by the processing unit (2a1). The medium may be various storage media readable by the computer (2a) or a communication line connected to the communication interface (2a3). The processing unit (2a1) may be a CPU (Central Processing Unit). The storage unit (2a2) may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface (2a3) may communicate with the plasma processing device (1) through a communication line such as a LAN (Local Area Network).

[0031] Below, an example of the configuration of an inductively coupled plasma processing device as an example of a plasma processing device (1) will be described. FIG. 2 is a drawing for explaining an example of the configuration of an inductively coupled plasma processing device.

[0032] An inductively coupled plasma processing device (1) comprises a plasma processing chamber (10), a gas supply unit (20), a power supply (30), and an exhaust system (40). The plasma processing chamber (10) comprises a dielectric window (101). Additionally, the plasma processing device (1) comprises a substrate support (11), a gas introduction unit, and an antenna (14). The substrate support (11) is positioned within the plasma processing chamber (10). The antenna (14) is positioned above or above the plasma processing chamber (10) (i.e. above or above the dielectric window (101)). The plasma processing chamber (10) has a plasma processing space (10s) defined by the dielectric window (101), the side wall (102) of the plasma processing chamber (10), and the substrate support (11). The plasma processing chamber (10) is grounded.

[0033] The substrate support portion (11) includes a main body portion (111) and a ring assembly (112). The main body portion (111) has a central region (111a) for supporting a substrate (W) and a ring-shaped region (111b) for supporting a ring assembly (112). A wafer is an example of a substrate (W). The ring-shaped region (111b) of the main body portion (111) surrounds the central region (111a) of the main body portion (111) when viewed in a planar view. A substrate (W) is placed on the central region (111a) of the main body portion (111), and a ring assembly (112) is placed on the ring-shaped region (111b) of the main body portion (111) to surround the substrate (W) on the central region (111a) of the main body portion (111). Accordingly, the central region (111a) is also called a substrate support surface for supporting the substrate (W), and the ring-shaped region (111b) is also called a ring support surface for supporting the ring assembly (112).

[0034] In one embodiment, the main body (111) includes a base (1110) and an electrostatic chuck (1111). The base (1110) includes a conductive member. The conductive member of the base (1110) can function as a bias electrode. The electrostatic chuck (1111) is disposed on the base (1110). The electrostatic chuck (1111) includes a ceramic member (1111a) and an electrostatic electrode (1111b) disposed within the ceramic member (1111a). The ceramic member (1111a) has a central region (111a). In one embodiment, the ceramic member (1111a) also has an annular region (111b). Additionally, another member surrounding the electrostatic chuck (1111), such as an annular electrostatic chuck or an annular insulating member, may have an annular region (111b). In this case, the ring assembly (112) may be disposed on a ring-shaped electrostatic chuck or a ring-shaped insulating member, or may be disposed on both sides of the electrostatic chuck (1111) and the ring-shaped insulating member. Additionally, at least one RF / DC electrode coupled to the RF power source (31) and / or DC power source (32) described later may be disposed within the ceramic member (1111a). In this case, at least one RF / DC electrode functions as a bias electrode. Additionally, the conductive member of the base (1110) and at least one RF / DC electrode may function as a plurality of bias electrodes. Additionally, an electrostatic electrode (1111b) may function as a bias electrode. Accordingly, the substrate support (11) includes at least one bias electrode.

[0035] The ring assembly (112) includes one or more ring-shaped members. In one embodiment, the one or more ring-shaped members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0036] Additionally, the substrate support (11) may include a temperature control module configured to control at least one of the electrostatic chuck (1111), ring assembly (112), and substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path (1110a), or a combination thereof. A heat transfer fluid, such as brine or gas, flows through the flow path (1110a). In one embodiment, the flow path (1110a) is formed within the base (1110), and one or more heaters are disposed within the ceramic member (1111a) of the electrostatic chuck (1111). Additionally, the substrate support (11) may include a heat transfer gas supply unit configured to supply a heat transfer gas to the gap between the back surface of the substrate (W) and the central region (111a).

[0037] A gas injector is configured to introduce at least one processing gas from a gas supply unit (20) into a plasma processing space (10s). In one embodiment, the gas injector includes a center gas injector (CGI) (13). The center gas injector (13) is positioned above a substrate support (11) and is mounted in a central opening formed in a dielectric window (101). The center gas injector (13) has at least one gas supply port (13a), at least one gas flow path (13b), and at least one gas injector port (13c). Processing gas supplied to the gas supply port (13a) passes through the gas flow path (13b) and is introduced into the plasma processing space (10s) from the gas injector port (13c). Additionally, the gas injector may include one or more side gas injectors (SGI) attached to one or more openings formed in a side wall (102), in addition to or instead of the center gas injector (13).

[0038] The gas supply unit (20) may include at least one gas source (21) and at least one flow controller (22). In one embodiment, the gas supply unit (20) is configured to supply at least one processing gas from each corresponding gas source (21) through each corresponding flow controller (22) to the gas introduction unit. Each flow controller (22) may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit (20) may include at least one flow modulation device for modulating or pulsed the flow rate of at least one processing gas.

[0039] The power supply (30) includes an RF power supply (31) coupled to the plasma processing chamber (10) through at least one impedance matching circuit. The RF power supply (31) is configured to supply at least one RF signal (RF power) to at least one bias electrode and antenna (14). By this, plasma is formed from at least one processing gas supplied to the plasma processing space (10s). Thus, the RF power supply (31) can function as at least part of the plasma generation unit (12). Additionally, by supplying the bias RF signal to at least one bias electrode, a bias potential is generated in the substrate (W), thereby attracting ions in the formed plasma to the substrate (W).

[0040] In one embodiment, the RF power supply (31) includes a first RF generating unit (31a) and a second RF generating unit (31b). The first RF generating unit (31a) is coupled to the antenna (14) through at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for generating plasma. In one embodiment, the source RF signal has a frequency within the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit (31a) may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to the antenna (14).

[0041] The second RF generation unit (31b) is coupled to at least one bias electrode through at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency within the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit (31b) may be configured to generate a plurality of bias RF signals having different frequencies. One or more generated bias RF signals are supplied to at least one bias electrode. Additionally, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0042] Additionally, the power supply (30) may include a DC power supply (32) coupled to the plasma processing chamber (10). The DC power supply (32) includes a bias DC generating unit (32a). In one embodiment, the bias DC generating unit (32a) is connected to at least one bias electrode and configured to generate a bias DC signal. The generated bias DC signal is applied to at least one bias electrode.

[0043] In various embodiments, the bias DC signal may be pulsed. In this case, a sequence of voltage pulses is applied to at least one bias electrode. The voltage pulse may have a pulse waveform of a rectangular, trapezoidal, triangular, or a combination thereof. In one embodiment, a waveform generator for generating a sequence of voltage pulses from a DC signal is connected between the bias DC generator (32a) and at least one bias electrode. Thus, the bias DC generator (32a) and the waveform generator constitute a voltage pulse generator. The voltage pulse may have positive polarity or negative polarity. Additionally, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Additionally, the bias DC generator (32a) may be installed in addition to the RF power source (31) or installed instead of the second RF generator (31b).

[0044] The antenna (14) includes one or more coils. In one embodiment, the antenna (14) may include an outer coil and an inner coil arranged coaxially. In this case, the RF power supply (31) may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generator may be connected to both the outer coil and the inner coil, or separate RF generators may be connected to the outer coil and the inner coil, respectively.

[0045] The exhaust system (40) may be connected, for example, to a gas outlet (10e) installed at the bottom of the plasma processing chamber (10). The exhaust system (40) may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space (10s) is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0046] <RF 시스템의 일 예>

[0047] FIG. 3 is a diagram showing an example of a system configuration from a first RF generator (31a) to a chamber (10) (hereinafter also referred to as the “RF system”). The first RF generator (31a) is connected to a plasma processing chamber (10) (hereinafter also referred to as the “chamber (10)”) via a transmission path (TL). In one embodiment, the first RF generator (31a) may be connected to an antenna (14) (see FIG. 2) of a plasma processing device (1). The transmission path (TL) is a signal line through which an RF signal (source RF signal) generated by the first RF generator (31a) propagates. In the transmission path (TL), a matching device (33) and a measuring device (34) are arranged in this order from upstream (the first RF generator (31a)) to downstream (the chamber (10)). That is, the first RF generation unit (31a) is coupled to the chamber (10) through a matching unit (33) and a measuring unit (34) on the transmission path (TL). An analyzer (35) is connected to the measuring unit (34). The RF system can be controlled by a controller (CT).

[0048] The first RF generation unit (31a) is configured to generate a modulated RF signal in which multiple frequency components are superimposed. The first RF generation unit (31a) includes a waveform output unit (310a) and a power amplifier (312a). Additionally, the first RF generation unit (31a) may generate an RF signal consisting of a single frequency component.

[0049] The waveform output section (310a) may be configured to output a broadband RF signal having multiple frequency components superimposed at once. The power amplifier (312a) adjusts the power of the broadband RF signal output from the waveform output section (310a) and outputs it as a modulated RF signal. The controller (CT) controls the output of the broadband RF signal from the waveform output section (310a) so that the modulated RF signal has a desired center frequency, bandwidth, and pitch. Additionally, the controller (CT) controls the amplification rate of the broadband RF signal in the power amplifier (312a) so that the modulated RF signal has a desired power.

[0050] The waveform output section (310a) may be configured to sequentially output sweep RF signals with different frequencies. The power amplifier (312a) sequentially adjusts the power of the sweep RF signals output from the waveform output section (310a) and outputs them as modulated RF signals. The controller (CT) controls each output of a plurality of sweep RF signals from the waveform output section (310a) so that the modulated RF signal becomes a desired center frequency, bandwidth, and pitch. Additionally, the controller (CT) controls the amplification rate of each sweep RF signal in the power amplifier (312a) so that the modulated RF signal becomes a desired power.

[0051] The matching unit (33) is configured to match the impedance of the first RF generating unit (31a) and the chamber (10). The matching unit (33) may include a matching circuit comprising a variable reactance element (e.g., a variable capacitor, a variable inductor, etc.). By controlling the variable reactance element of the matching circuit by a controller (CT), the impedance of the first RF generating unit (31a) with respect to the chamber (10) may be controlled.

[0052] The measuring instrument (34) is configured to periodically or continuously detect the RF reflection characteristics of an RF signal propagating through a transmission path (TL) and output them to an analyzer (35). The RF reflection characteristics are parameters regarding the amount of return (power of the reflected wave) relative to the output (power of the traveling wave) of the RF signal in the transmission path (TL). In the example shown in FIG. 3, what is detected by the measuring instrument (34) and output to the analyzer (35) is the reflection characteristics of the RF signal at the output terminal (node) of the matching device (33).

[0053] RF reflection characteristics may include one or more of the following (a) to (e).

[0054] (a) Ratio (Ra) of the power of the traveling wave (Pf) and the power of the reflected wave (Pr) (see Equation 1) or ratio (Rp) (Ra × 100[%])

[0055] (b) Resistance component of impedance (R) [Ω] (refer to Equation 2)

[0056] (c) Reflection coefficient (Γ) (refer to Equation 3)

[0057] (d) Return Loss (RL) [dB] (Refer to Equation 4)

[0058] (e) S parameter (S 11 )[dB](Refer to Equation 5)

[0059] [Mathematical Formula 1]

[0060]

[0061] [Mathematical Formula 2]

[0062]

[0063] [Mathematical Formula 3]

[0064]

[0065] [Mathematical Formula 4]

[0066]

[0067] [Mathematical Formula 5]

[0068]

[0069] The measuring device (34) may include a directional coupler. The directional coupler is configured to separate parts of the traveling wave and reflected wave of the RF signal propagating through the transmission path (TL). The measuring device (34) may use the directional coupler to separate parts of the traveling wave and reflected wave of the RF signal propagating through the transmission path (TL) and obtain the power (Pf) of the traveling wave and the power (Pr) of the reflected wave. Additionally, the measuring device (34) may include a VI sensor. The VI sensor is configured to detect the electrical characteristics of the RF signal. The measuring device (34) may use the VI sensor to obtain the RMS value (V) of the voltage, the RMS value (I) of the current, and the phase difference (θ) between the voltage and the current of the RF signal propagating through the transmission path (TL).

[0070] The analyzer (35) is configured to determine the RF reflection spectrum for each frequency based on the RF reflection characteristics detected by the measuring instrument (34). The RF reflection spectrum is data containing the RF reflection characteristics (amplitude) for each frequency. An example of the RF reflection spectrum will be described later using FIG. 6. In one example, the analyzer (35) is a spectrum analyzer having a Fast Fourier Transform (FFT) function. Additionally, the analyzer (35) may be configured as part of the controller (CT).

[0071] The controller (CT) may be equipped with a processor (processing unit), a memory unit, and a communication interface. The controller (CT) may be configured to control each component of the RF system to execute each process described below. In one embodiment, part or all of the controller (CT) may be included in the control unit (2) of the plasma processing system (see FIG. 1 and FIG. 2). In addition, in one embodiment, part of the controller (CT) may be included in other components of the RF system (first RF generation unit (31a), matching unit (33), measuring unit (34) and / or analyzer (35)) as part of said other components.

[0072] FIG. 4 is a diagram showing another example of an RF system. In the example shown in FIG. 4, the positional relationship of the matching unit (33) and the measuring unit (34) is opposite to that of the example shown in FIG. 3. That is, in the example shown in FIG. 4, the measuring unit (34) and the matching unit (33) are arranged in this order from upstream to downstream in the transmission path (TL). In the example shown in FIG. 4, what is detected by the measuring unit (34) and output to the analyzer (35) is the reflection characteristic of the RF signal at the input terminal (node) of the matching circuit (33).

[0073] An example of a plasma treatment method

[0074] FIG. 5 is a flowchart illustrating an example of a plasma processing method (hereinafter also referred to as "Method (MT)") according to one exemplary embodiment. FIG. 6 is a diagram illustrating the modulated RF signal and RF reflection spectrum in each process of the Method (MT). As shown in FIG. 5, the Method (MT) includes a process ST1 for igniting the plasma, a process ST2 for performing a matching operation, and a process ST3 for maintaining the plasma. The processing in each process may be performed using the aforementioned plasma processing apparatus (1) (Figs. 1, 2) and RF system (Figs. 3, 4). Hereinafter, an example is described in which the control unit (2) and / or controller (CT) controls each part of the plasma processing apparatus (1) and RF system to execute the Method (MT).

[0075] (Process ST1: Plasma Ignition)

[0076] FIG. 7 is a flowchart illustrating an example of process ST1. In process ST1, plasma is generated within a chamber (10). As shown in FIG. 7, process ST1 includes process ST11, which outputs a first modulated RF signal; process ST12, which detects RF reflection characteristics; process ST13, which acquires an RF reflection spectrum; process ST14, which determines an ignition frequency; and process ST15, which outputs a second modulated RF signal. Process ST1 is an example of a plasma ignition sequence in the present disclosure.

[0077] At the start of process ST1, a gas for generating plasma may be supplied from a gas supply unit (20) into the chamber (10). At this time, the pressure inside the chamber (10) may be reduced to a given set pressure. Additionally, at the start of process ST1, a substrate (W) may be provided on a substrate support (11) of the chamber (10). At this time, the temperature of the substrate support (11) and / or the substrate (W) may be adjusted to a given set temperature. Additionally, process ST1 may be executed without a substrate (W) being provided inside the chamber (10).

[0078] In process ST11, a first modulated RF signal is output from the first RF generator (31a) to the chamber (10). The first modulated RF signal may be generated by simultaneously outputting a broadband RF signal having multiple frequency components superimposed from the waveform output unit (310a) of the first RF generator (31a). Additionally, the first modulated RF signal may be generated by sequentially outputting sweep RF signals with different frequencies from the waveform output unit (310a) of the first RF generator (31a).

[0079] In column (A) of the “modulated RF signal” in FIG. 6, an example of a first modulated RF signal is shown. The first modulated RF signal has multiple frequency components in a first frequency band (bandwidth: BD1). The pitch (Pt1) between each frequency component of the first modulated RF signal may be constant, or may differ in some or all. The first frequency band may be set so that the design frequency of the first RF generation unit (31a) (the design frequency of the source RF signal for plasma generation, e.g., 27 MHz) becomes the center frequency. In one embodiment, the bandwidth (BD1) of the first frequency band is less than 20% (e.g., 5.4 MHz) of the design frequency. In one embodiment, the bandwidth (BD1) of the first frequency band is less than 10% (e.g., 2.7 MHz) of the design frequency.

[0080] The first modulated RF signal has a first power level (P1) (W). The first power level (P1) is a power level such that no plasma is generated within the chamber (10). In one example, the first power level (P1) is less than 10W, less than 5W, or less than 1W. The first power level (P1) may also be determined based on the reflection resistance of the power source (30) including the first RF generating unit (31a).

[0081] In process ST12, RF reflection characteristics are detected. The measuring instrument (34) detects the RF reflection characteristics of the first modulated RF signal propagating through the transmission path (TL) and outputs them to the analyzer (35).

[0082] In process ST13, an RF reflection spectrum is acquired. The analyzer (35) acquires a frequency-specific RF reflection spectrum corresponding to the first modulated RF signal based on the RF reflection characteristics of the first modulated RF signal output from the measuring instrument (34).

[0083] Column (A) of the “RF Reflection Spectrum” in FIG. 6 shows an example of an RF reflection spectrum obtained in process ST13. In this example, the amplitude (RF reflection characteristic) of the RF reflection spectrum is the ratio (Rp) [%] of the power of the traveling wave (Pf) and the power of the reflected wave (Pr). The frequency band of the RF reflection spectrum is the same as the first frequency band.

[0084] In process ST14, the ignition frequency is determined. The ignition frequency is determined based on the RF reflection spectrum obtained in process ST13. The ignition frequency may be the frequency in the RF reflection spectrum where the RF reflection characteristics are best, that is, the frequency where the return loss is minimized. For example, in the example shown in column (A) of the “RF reflection spectrum” in FIG. 6, the frequency (Fa) where the amplitude of the RF reflection spectrum (ratio (Rp) [%]) is minimized may be determined as the ignition frequency.

[0085] In process ST15, a second modulated RF signal is output from the first RF generator (31a) to the chamber (10). The second modulated RF signal may be generated by simultaneously outputting a broadband RF signal having multiple frequency components superimposed from the waveform output unit (310a) of the first RF generator (31a). Additionally, the second modulated RF signal may be generated by sequentially outputting sweep RF signals with different frequencies from the waveform output unit (310a) of the first RF generator (31a).

[0086] In column (B) of the “modulated RF signal” in FIG. 6, an example of a second modulated RF signal is shown. The second modulated RF signal has multiple frequency components in a second frequency band (bandwidth: BD2). The bandwidth (BD2) of the second frequency band is narrower than the bandwidth (BD1) of the first frequency band. The second frequency band may be set such that the ignition frequency (Fa) determined in process ST14 becomes the center frequency. In one embodiment, the bandwidth (BD2) of the second frequency band is less than 10% of the design frequency. In one embodiment, the bandwidth (BD2) of the second frequency band is within the range of 1% to 10% of the design frequency. The pitch (Pt2) between each frequency component of the second modulated RF signal may be constant, or some or all may differ. The pitch (Pt2) between each frequency component of the second modulated RF signal may be smaller than the pitch (Pt1) between each frequency component of the first modulated RF signal.

[0087] The second modulated RF signal has a second power level (P2) (W). The second power level (P2) is a power level capable of generating plasma within the chamber (10). That is, the second power level (P2) is greater than the first power level (P1). Additionally, the second modulated RF signal may not have the second power level (P2) at the start of process ST15, or it may gradually increase from the first power level (P1) to the second power level (P2).

[0088] In process ST15, plasma is generated from the gas in the chamber (10). By this, process ST1 is terminated.

[0089] In process ST1, the ignition frequency with the smallest return loss is determined by using the RF reflection spectrum of the first modulated RF signal. Then, plasma is generated in the chamber (10) using the second modulated RF signal. The ignition frequency is a frequency at which plasma is easily generated. By doing so, failure of plasma ignition can be suppressed. Additionally, since the ignition frequency is determined in advance, the bandwidth (BD2) of the second modulated RF signal can be made narrower than the bandwidth (BD1) of the first modulated RF signal. By doing so, the absolute amount of reflected waves (hereinafter also referred to as "RF reflection") propagating through the transmission path (TL) during plasma ignition can be reduced.

[0090] Column (B) of the “RF Reflection Spectrum” in FIG. 6 shows an example of the RF reflection spectrum at the end of process ST15, that is, immediately after plasma is generated in the chamber (10). In this example, the frequency (Fb) at which the RF reflection characteristics are best deviates from the ignition frequency (Fa). This is because the RF reflection characteristics change due to the change in the load of the chamber (10) caused by plasma generation. In such cases, if the source RF signal is a single frequency component, RF reflection increases immediately after plasma generation, and stability (robustness) may decrease. In this regard, process ST1 generates plasma using a second modulated RF signal. The second modulated RF signal has a second frequency band (bandwidth: BD2) with the ignition frequency (Fa) as the center frequency. That is, the second modulated RF signal includes frequency components around the ignition frequency (Fa) in addition to the ignition frequency (Fa). Therefore, even if the load of the chamber (10) changes immediately after plasma ignition and the frequency at which the RF reflection characteristics are best changes (e.g., from Fa to Fb), the frequency component after the change can still be included. By doing so, stability (robustness) immediately after plasma ignition can be improved.

[0091] (Process ST2: Matching operation)

[0092] FIG. 8 is a flowchart illustrating an example of process ST2. In process ST2, an impedance matching operation (hereinafter simply referred to as "matching operation") is performed. The matching operation is an operation to match the impedance of the first RF generator (31a) and the chamber (10) to reduce RF reflection. Through the matching operation, power can be efficiently supplied to the plasma inside the chamber (10). In one embodiment, the matching operation includes changing the frequency of the source RF signal output from the first RF generator (31a) and / or changing the reactance of the variable reactance element of the matching device (33). In one embodiment, the matching operation includes making the impedance viewed from the input terminal of the matching device (33) toward the load side a characteristic impedance (e.g., 50Ω).

[0093] As shown in FIG. 8, process ST2 includes process ST21 for outputting a modulated RF signal, process ST22 for detecting RF reflection characteristics, process ST23 for acquiring an RF reflection spectrum, process ST24 for determining a target frequency, process ST25 for determining a frequency band of the modulated RF signal, and process ST26 for determining whether the bandwidth of the said frequency band is within the target width. Processes ST21 to ST26 are repeated multiple times until the determination of process ST26 is positive. The duration of one cycle of processes ST21 to ST26 may be, for example, 1 μ second to 10 m second. Process ST2 is an example of an impedance matching sequence in the present disclosure.

[0094] In process ST21, a modulated RF signal is output from the first RF generator (31a) to the chamber (10). The modulated RF signal may be generated by simultaneously outputting a broadband RF signal in which multiple frequency components are superimposed from the waveform output section (310a) of the first RF generator (31a). Additionally, the modulated RF signal may be generated by sequentially outputting sweep RF signals with different frequencies from the waveform output section (310a) of the first RF generator (31a). In process ST21, the variable reactance element of the matching circuit of the matching unit (33) may be changed.

[0095] As described above, processes ST21 through ST26 can be repeated multiple times. In the first process ST21, the modulated RF signal may be the same as the second modulated RF signal (column (B) of “Modulated RF Signal” in FIG. 6). Column (C) of “Modulated RF Signal” in FIG. 6 shows an example of the modulated RF signal output from the Nth (N>1) process ST21. As described below, the bandwidth of the modulated RF signal output from the first RF generation unit (31a) narrows with each repetition of process ST21. The bandwidth (BDN) of the modulated RF signal output from the Nth process ST21 may be narrower than the bandwidth of the modulated RF signal output from the previous (1st to N-1st) process ST21. The pitch between each frequency component of the modulated RF signal may be constant, or some or all may be different.

[0096] In one embodiment, the power level of the modulated RF signal may be constant (e.g., a second power level (P2)) regardless of which process ST21 is performed. In one embodiment, the power level of the modulated RF signal may be changed one or more times during the repetition of process ST21. For example, if the RF reflection characteristics deteriorate during the matching operation and it becomes difficult to maintain the plasma, the power level of the modulated RF signal output from process ST21 may be increased. This may suppress the failure of the plasma.

[0097] In process ST22, RF reflection characteristics are detected. The measuring instrument (34) detects the RF reflection characteristics of the modulated RF signal propagating through the transmission path (TL) and outputs them to the analyzer (35).

[0098] In process ST23, an RF reflection spectrum is acquired. The analyzer (35) acquires an RF reflection spectrum for each frequency corresponding to the modulated RF signal based on the RF reflection characteristics of the modulated RF signal output from the measuring instrument (34). In column (B) of the “RF Reflection Spectrum” in FIG. 6, an example of an RF reflection spectrum acquired in the first process ST23 is shown. In column (C) of the “RF Reflection Spectrum” in FIG. 6, an example of an RF reflection spectrum acquired in the Nth (N>1) process ST23 is shown.

[0099] In process ST24, a target frequency is determined. The target frequency is determined based on the RF reflection spectrum obtained in process ST23. The target frequency may be the frequency in which the RF reflection characteristics are best in the said RF reflection spectrum, that is, the frequency at which the return loss is minimized. For example, in the examples shown in columns (B) and (C) of the “RF reflection spectrum” in FIG. 6, the frequencies (Fb and Fn) at which the amplitude of the RF reflection spectrum (ratio (Rp) [%]) is minimized may be determined as the target frequencies, respectively.

[0100] In process ST25, the frequency band of the modulated RF signal is determined. The frequency band is set such that the bandwidth is narrower than the bandwidth of the modulated RF signal output from the previous process ST21, while using the target frequency (e.g., frequency (Fb or Fn)) determined in process ST24 as the center frequency. That is, the determined bandwidth of the modulated RF signal gradually narrows with each repetition of process ST25. For example, the frequency band may be set such that the bandwidth narrows by 0.1 kHz to 500 kHz with each repetition of process ST25.

[0101] In process ST26, it is determined whether the bandwidth of the frequency band determined in process ST25 is within the target width. In one embodiment, the target width may be within the range of 0.1 to 1% of the design frequency (e.g., 27 MHz) of the first RF generation unit (31a).

[0102] If the bandwidth of the frequency band determined in process ST25 is greater than or equal to the target width (process ST26: NO), return to process ST21. At this time, the modulated RF signal having the frequency band determined in process ST25 is set as the modulated RF signal output in the next step, process ST21.

[0103] If the bandwidth of the frequency band determined in process ST25 is less than the target width (process ST26: YES), the matching operation of process ST2 is terminated. At this time, a modulated RF signal having the frequency band determined in process ST25 is set as a matched modulated RF signal.

[0104] In column (D) of “Modulated RF Signal” in FIG. 6, an example of a matched modulated RF signal is shown. Also, in column (D) of “RF Reflection Spectrum,” an RF reflection spectrum corresponding to the matched modulated RF signal is shown. The frequency band (bandwidth: BDL) of the matched modulated RF signal is the frequency band determined in the final process ST25. The power level (PL) of the matched modulated RF signal is a power level capable of generating plasma within the chamber (10). The power level (PL) may be the same as the second power level (P2) or may be different. The pitch (PtL) between each frequency component of the matched modulated RF signal may be constant, or may be partially or entirely different.

[0105] In process ST2, a target frequency, that is, the frequency at which RF reflection (return loss) is smallest at that point, is determined, and a matching operation is performed by gradually narrowing the frequency band while using the said target frequency as the center frequency of the modulated RF signal. By doing so, the impedance matching position can be suppressed from rapidly shifting from a low RF reflection region to a high RF reflection region, thereby preventing a rapid increase in RF reflection. Furthermore, the impedance matching position can be suppressed from shifting to a total reflection region where there is no sensitivity to RF reflection, thereby preventing the loss of the matching direction (the direction of reduction of RF reflection in response to changes in the frequency and / or reactance of the source RF signal) or the plasma from being deactivated. According to process ST2, the matching operation can be stabilized.

[0106] However, depending on the state of the gas or plasma inside the chamber (10), there may be cases where RF reflection cannot be sufficiently reduced even after performing a matching operation. In such cases, if the determination of whether the RF reflection characteristic has reached a given threshold value is used as the criterion for completing the matching operation, a situation may occur where the matching operation cannot be completed indefinitely. In this regard, in process ST2, the matching operation is completed when the bandwidth of the frequency band determined in process ST25 is less than the target width; thus, even in such cases, the matching position where the RF reflection is minimized can be found and the matching operation completed. Furthermore, in such cases, the power level (PL) of the matching modulated RF signal can be set high to increase the power supplied to the plasma.

[0107] (Process ST3: Plasma sustainment operation)

[0108] FIG. 9 is a flowchart illustrating an example of process ST3. In process ST3, a plasma holding operation is performed. The plasma holding operation is an operation to maintain plasma within the chamber (10) and to perform a desired process using said plasma. As shown in FIG. 9, process ST3 includes process ST31, which outputs a third modulated RF signal and a fourth modulated RF signal; process ST32, which detects RF reflection characteristics; process S33, which acquires an RF reflection spectrum; process ST34, which determines a target frequency; process ST35, which determines the frequency band of the modulated RF signal; and process ST36, which determines a stopping condition. Processes ST31 through ST36 are repeated multiple times until the determination of process ST36 is positive. Process ST3 is an example of a plasma holding sequence in the present disclosure.

[0109] In process ST31, a third modulated RF signal and a fourth modulated RF signal are output from the first RF generator (31a) to the chamber (10). The third modulated RF signal and the fourth modulated RF signal may be generated by simultaneously outputting a broadband RF signal having multiple frequency components superimposed from the waveform output unit (310a) of the first RF generator (31a). Additionally, the third modulated RF signal and the fourth modulated RF signal may be generated by sequentially outputting sweep RF signals with different frequencies from the waveform output unit (310a) of the first RF generator (31a).

[0110] In column (E) of the “modulated RF signal” in FIG. 6, an example of the third modulated RF signal and the fourth modulated RF signal output from process ST31 is shown. The third modulated RF signal has multiple frequency components in the third frequency band (bandwidth: BD3). The bandwidth (BD3) of the third modulated RF signal may be, for example, within the range of 0.1 to 1% of the design frequency. The pitch (Pt3) between each frequency component of the third modulated RF signal may be constant, or some or all may be different. The third modulated RF signal has a third power level (P3) (W). The third power level (P3) is a power level capable of generating plasma within the chamber (10). The third power level (P3) may be the same as or different from the second power level. As described above, processes ST31 to ST36 can be executed repeatedly multiple times. The third modulated RF signal output from the first process ST31 may be a matched modulated RF signal determined in process ST25.

[0111] The fourth modulated RF signal has multiple frequency components in the fourth frequency band (bandwidth: BD4). The center frequency of the fourth frequency band matches the center frequency of the third frequency band. The bandwidth (BD4) of the fourth modulated RF signal may be, for example, within the range of 1 to 10% of the design frequency. The fourth modulated RF signal may not have frequency components in the frequency band that overlaps with the third frequency band. The pitch (Pt4) between each frequency component of the fourth modulated RF signal at locations that do not overlap with the third frequency band may be constant, or may differ in some or all. The pitch (Pt4) may be greater than the pitch (Pt3) between each frequency component of the third modulated RF signal. The fourth modulated RF signal has a fourth power level (P4) (W). The fourth power level (P4) is a power level such that no plasma is generated within the chamber (10). The fourth power level (P4) may be the same as or different from the first power level (P1). In one example, the fourth power level (P4) is less than 10W, less than 5W, or less than 1W. The fourth power level (P4) may be determined based on the reflection resistance of the power source (30) including the first RF generating unit (31a).

[0112] In process ST32, RF reflection characteristics are detected. The measuring instrument (34) detects the RF reflection characteristics of the third modulated RF signal and the fourth modulated RF signal propagating through the transmission path (TL) and outputs them to the analyzer (35).

[0113] In process ST33, an RF reflection spectrum is acquired. Based on the output from the measuring instrument (34), the analyzer (35) acquires RF reflection spectra for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal. In column (E) of the “RF reflection spectrum” in FIG. 6, an example of an RF reflection spectrum acquired in process ST23 is shown.

[0114] In process ST34, a target frequency is determined. The target frequency is determined based on the RF reflection spectrum obtained in process ST33. The target frequency may be the frequency in the RF reflection spectrum where the RF reflection characteristics are best, that is, the frequency where the return loss is minimized. For example, in the example shown in column (E) of the “RF reflection spectrum” in FIG. 6, the frequency (Fx) where the amplitude of the RF reflection spectrum (ratio (Rp) [%]) is minimized may be determined as the target frequency.

[0115] In process ST35, the frequency bands of the third modulated RF signal and the fourth modulated RF signal are determined. The frequency bands of both the third modulated RF signal and the fourth modulated RF signal are set so that the target frequency (frequency (Fx)) determined in process ST34 becomes the center frequency. That is, the third modulated RF signal and the fourth modulated RF signal are adjusted so that the frequency at which the RF reflection (return loss) is smallest at that point becomes the center frequency. The bandwidth (BD3) of the third modulated RF signal may be, for example, within a range of 0.1 to 1% of the design frequency. The bandwidth (BD4) of the fourth modulated RF signal may be within a range of 1 to 10% of the design frequency.

[0116] In process ST36, it is determined whether the stop condition is satisfied. If the stop condition is not satisfied, the process returns to process ST31. If the stop condition is satisfied, process ST3 is terminated. The stop condition may be appropriately set, for example, whether the process is completed by the plasma in the chamber (10), the time after generating the plasma, the number of repetition cycles of process ST3, etc.

[0117] In process ST3, an RF reflection spectrum corresponding to a third modulated RF signal having a third frequency band and a fourth modulated RF signal having a fourth frequency band is acquired. The third frequency band and the fourth frequency band are adjusted periodically so that the frequency at which the RF reflection (return loss) is smallest at that time becomes the center frequency. Therefore, even if the RF reflection characteristics change due to a change in load during the plasma process in the chamber (10), the change can be captured and followed. As a result, it is possible to suppress the impedance matching position from rapidly shifting from a low RF reflection region to a high RF reflection region, causing a surge in RF reflection, or shifting to a total reflection region where there is no sensitivity to RF reflection, thereby losing the matching direction, or causing the plasma to fail. Additionally, for frequency bands away from the center frequency (frequency bands where RF reflection is relatively large), an RF reflection spectrum is acquired by a fourth modulated RF signal having a fourth power level such that no plasma is generated. This allows the absolute amount of RF reflection to be reduced. Additionally, in one embodiment, process ST3 may be executed using only the third modulation RF signal without using the fourth modulation RF signal.

[0118] As described above, according to the method (MT), the matching operation can be stabilized.

[0119] The present disclosure may be carried out in a plasma processing device (1) using any plasma source, such as capacitively coupled plasma or microwave plasma, in addition to an inductively coupled plasma processing device (1). For example, an RF system (Fig. 3, Fig. 4) may be coupled to a capacitively coupled plasma processing device. A capacitively coupled plasma processing device includes an upper electrode and a lower electrode. The lower electrode is placed within a substrate support in a chamber, and the upper electrode is placed above the substrate support. Then, a first RF generating unit (31a) is connected to the upper electrode or the lower electrode through an impedance matching circuit. By this, the RF system may be coupled to the chamber of the capacitively coupled plasma processing. Also, for example, the method (MT) may be carried out in a capacitively coupled plasma processing device.

[0120] The embodiments of the present disclosure further include the following aspects.

[0121] (Appendix 1)

[0122] chamber and,

[0123] An antenna positioned above the chamber, and

[0124] An RF generating unit connected to the above antenna, and

[0125] A measuring device configured to detect RF reflection characteristics at a node between the antenna and the RF generating unit, and

[0126] An analyzer configured to determine the RF reflection spectrum for each frequency based on the above RF reflection characteristics, and

[0127] It is equipped with a control unit configured to execute a plasma ignition sequence,

[0128] The above plasma ignition sequence is,

[0129] (a1) Controlling the RF generator to output a first modulated RF signal having multiple frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber, and

[0130] (a2) obtaining a frequency-specific RF reflection spectrum corresponding to the first modulated RF signal from the analyzer, and

[0131] (a3) Determining the ignition frequency based on the RF reflection spectrum for each frequency obtained in (a2), and

[0132] (a4) Controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal has a power level capable of generating plasma in the chamber.

[0133] Plasma processing device.

[0134] (Appendix 2)

[0135] In Book 1,

[0136] A plasma processing device in which the center frequency of the second frequency band is the ignition frequency.

[0137] (Appendix 3)

[0138] In Book 1 or Book 2,

[0139] The above control unit is configured to execute an impedance matching sequence after the plasma ignition sequence, and

[0140] The above impedance matching sequence is,

[0141] (b1) Controlling the RF generator to output a modulated RF signal having multiple frequency components, wherein the modulated RF signal has a power level capable of generating plasma in the chamber, and

[0142] (b2) obtaining a frequency-specific RF reflection spectrum corresponding to the modulated RF signal from the analyzer, and

[0143] (b3) Determining the target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each frequency obtained in (b2) above, and

[0144] (b4) A plasma processing apparatus comprising narrowing the frequency band of the modulated RF signal output from the RF generation unit while adjusting the frequency band such that the center frequency of the frequency band becomes the target frequency.

[0145] (Appendix 4)

[0146] In Book 3,

[0147] The above impedance matching sequence further comprises (b5) repeating (b1) to (b4) until the frequency band of the modulated RF signal output from the RF generation unit becomes a target width, in a plasma processing apparatus.

[0148] (Appendix 5)

[0149] In any one of Books 1 to 4,

[0150] The above control unit is configured to execute a plasma maintenance sequence for maintaining plasma in the chamber after the above matching sequence, and

[0151] The above plasma maintenance sequence is,

[0152] (c1) Controlling the RF generator to output a third modulated RF signal having multiple frequency components and a fourth modulated RF signal having multiple frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber, the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal.

[0153] (c2) obtaining RF reflection spectra for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal from the analyzer, and

[0154] (c3) Determining the target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each frequency obtained in (c2) above, and

[0155] (c4) A plasma processing apparatus comprising setting the frequency band of the third modulated RF signal output from the RF generation unit such that the center frequency of the frequency band becomes the target frequency.

[0156] (Appendix 6)

[0157] In any one of Books 1 to 5,

[0158] The above RF reflection characteristics are, at the above node,

[0159] (a) Ratio or ratio of the power of the propagating wave to the power of the reflected wave [%],

[0160] (b) Resistance component of impedance [Ω],

[0161] (c) Reflection coefficient,

[0162] (d) Return loss [dB], and

[0163] (e) S parameter [dB]

[0164] A plasma processing device, which is one of the following.

[0165] (Appendix 7)

[0166] In any one of Books 1 to 6,

[0167] A plasma processing apparatus further comprising an impedance matching circuit connected between the chamber and the measuring instrument.

[0168] (Appendix 8)

[0169] In any one of Books 1 to 6,

[0170] A plasma processing apparatus further comprising an impedance matching circuit connected between the RF generating unit and the measuring instrument.

[0171] (Appendix 9)

[0172] In any one of Books 1 to 8,

[0173] The above RF generation unit is,

[0174] A waveform output unit configured to output a broadband RF signal in which multiple frequency components are superimposed, and

[0175] A plasma processing apparatus comprising a power amplifier configured to amplify the above broadband RF signal and output a modulated RF signal including a plurality of frequency components.

[0176] (Appendix 10)

[0177] In any one of Books 1 to 9,

[0178] The above RF generation unit is,

[0179] A waveform output unit configured to sequentially output sweep RF signals of different frequencies, and

[0180] A plasma processing apparatus comprising a power amplifier configured to sequentially amplify the above sweep RF signal and output a modulated RF signal including a plurality of frequency components.

[0181] (Appendix 11)

[0182] In any one of Books 1 to 10,

[0183] A plasma processing device having a power level of less than 10W such that the above plasma is not generated.

[0184] (Appendix 12)

[0185] In any one of Books 1 to 11,

[0186] The first frequency band has a bandwidth of less than 20% of the design frequency of the RF generation unit, and

[0187] A plasma processing device in which the second frequency band has a bandwidth of less than 10% of the design frequency.

[0188] (Appendix 13)

[0189] In Book 4 or Book 5,

[0190] A plasma processing device in which the above target width is within the range of 0.1 to 1% of the design frequency of the RF generation unit.

[0191] (Appendix 14)

[0192] In Book 4 or Book 5,

[0193] A plasma processing apparatus in which the frequency band of the modulated RF signal in (b5) above is narrowed from 0.1 kHz to 500 kHz.

[0194] (Appendix 15)

[0195] chamber and,

[0196] An antenna positioned above the chamber, and

[0197] An RF generating unit connected to the above antenna, and

[0198] A measuring device configured to detect RF reflection characteristics at a node between the antenna and the RF generating unit, and

[0199] An analyzer configured to determine the RF reflection spectrum for each frequency based on the above RF reflection characteristics, and

[0200] It has a control unit configured to execute a plasma maintenance sequence for maintaining plasma generated within the chamber, and

[0201] The above plasma maintenance sequence is,

[0202] (c1) Controlling the RF generator to output a third modulated RF signal having multiple frequency components and a fourth modulated RF signal having multiple frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber, the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal.

[0203] (c2) obtaining RF reflection spectra for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal from the analyzer, and

[0204] (c3) Determining the target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each frequency obtained in (c2) above, and

[0205] (c4) A frequency band of the third modulated RF signal output from the RF generation unit is set such that the center frequency of the frequency band becomes the target frequency.

[0206] Plasma processing device.

[0207] (Appendix 16)

[0208] An RF generating unit coupled to a chamber, and

[0209] A measuring device configured to detect RF reflection characteristics at a node between the chamber and the RF generating unit, and

[0210] An analyzer configured to determine the RF reflection spectrum for each frequency based on the above RF reflection characteristics, and

[0211] It is equipped with a control unit configured to execute a plasma ignition sequence,

[0212] The above plasma ignition sequence is,

[0213] (a1) Controlling the RF generator to output a first modulated RF signal having multiple frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber, and

[0214] (a2) acquiring RF reflection spectra for each frequency of the first modulated RF signal from the analyzer, and

[0215] (a3) Determining the ignition frequency based on the RF reflection spectrum for each frequency obtained in (a2), and

[0216] (a4) Controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal has a power level capable of generating plasma in the chamber.

[0217] RF system.

[0218] (Appendix 17)

[0219] A process for outputting a first modulated RF signal having multiple frequency components in a first frequency band to a chamber, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber, and

[0220] A process for detecting RF reflection characteristics from the above chamber, and

[0221] A process of acquiring an RF reflection spectrum for each frequency corresponding to the first modulated RF signal based on the RF reflection characteristics acquired above, and

[0222] A process for determining an ignition frequency based on the RF reflection spectrum for each of the above-mentioned frequencies, and

[0223] A process for outputting a second modulated RF signal having multiple frequency components in a second frequency band to the chamber, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal has a power level capable of generating plasma in the chamber.

[0224] Plasma treatment method.

[0225] (Appendix 18)

[0226] An RF generating unit coupled to a chamber, and

[0227] A measuring device configured to detect RF reflection characteristics at a node between the chamber and the RF generating unit, and

[0228] An analyzer configured to determine the RF reflection spectrum for each frequency based on the above RF reflection characteristics, and

[0229] It has a control unit configured to execute a plasma maintenance sequence for maintaining plasma generated within the chamber, and

[0230] The above plasma maintenance sequence is,

[0231] (c1) Controlling the RF generator to output a third modulated RF signal having multiple frequency components and a fourth modulated RF signal having multiple frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber, the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal.

[0232] (c2) obtaining RF reflection spectra for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal from the analyzer, and

[0233] (c3) Determining the target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each frequency obtained in (c2) above, and

[0234] (c4) A frequency band of the third modulated RF signal output from the RF generation unit is set such that the center frequency of the frequency band becomes the target frequency.

[0235] RF system.

[0236] (Appendix 19)

[0237] A process for outputting a third modulated RF signal having multiple frequency components and a fourth modulated RF signal having multiple frequency components to a chamber, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber, the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal.

[0238] A process for detecting RF reflection characteristics from the above chamber, and

[0239] Based on the RF reflection characteristics acquired above, acquiring RF reflection spectra for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal, and

[0240] Determining a target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each of the above-mentioned frequencies, and

[0241] A method comprising setting the frequency band of the third modulated RF signal such that the center frequency of the said frequency band becomes the target frequency.

[0242] Plasma treatment method.

[0243] Each of the above embodiments is described for illustrative purposes only and is not intended to limit the scope of the present disclosure. Each of the above embodiments may be modified in various ways without departing from the scope and spirit of the present disclosure. For example, some components of one embodiment may be added to another embodiment. Additionally, some components of one embodiment may be substituted with corresponding components of another embodiment. Explanation of the symbols

[0244] 1...Plasma processing device, 2...Control unit, 10...Plasma processing chamber, 14...Antenna, 31a...First RF generation unit, 33...Matching unit, 34...Measuring instrument, 35...Analyzer, CT...Controller

Claims

Claim 1 The apparatus comprises a chamber, an antenna disposed above the chamber, an RF generator connected to the antenna, a measuring device configured to detect RF reflection characteristics at a node between the antenna and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma ignition sequence, wherein the plasma ignition sequence comprises: (a1) controlling the RF generator to output a first modulated RF signal having a plurality of frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber; (a2) obtaining an RF reflection spectrum for each frequency corresponding to the first modulated RF signal from the analyzer; (a3) ​​determining an ignition frequency based on the RF reflection spectrum for each frequency obtained in (a2); and (a4) controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is greater than the first frequency band A plasma processing apparatus comprising a narrow band, wherein the second modulated RF signal has a power level capable of generating plasma in the chamber. Claim 2 A plasma treatment device according to claim 1, wherein the center frequency of the second frequency band is the ignition frequency. Claim 3 In paragraph 2, the control unit is configured to execute an impedance matching sequence after the plasma ignition sequence, and the impedance matching sequence comprises: (b1) controlling the RF generator to output a modulated RF signal having a plurality of frequency components, wherein the modulated RF signal has a power level capable of generating plasma in the chamber; (b2) obtaining an RF reflection spectrum for each frequency corresponding to the modulated RF signal from the analyzer; (b3) determining a target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum for each frequency obtained in (b2); and (b4) narrowing the frequency band of the modulated RF signal output from the RF generator while adjusting the center frequency of the frequency band to become the target frequency. Claim 4 A plasma processing apparatus according to paragraph 3, wherein the impedance matching sequence further comprises (b5) repeating (b1) to (b4) until the frequency band of the modulated RF signal output from the RF generation unit becomes a target width. Claim 5 In claim 4, the control unit is configured to execute a plasma maintenance sequence for maintaining plasma in the chamber after the matching sequence, and the plasma maintenance sequence comprises: (c1) controlling the RF generator to output a third modulated RF signal having a plurality of frequency components and a fourth modulated RF signal having a plurality of frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber and the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal; (c2) acquiring a frequency-specific RF reflection spectrum corresponding to the third modulated RF signal and the fourth modulated RF signal from the analyzer; (c3) determining a target frequency at which the RF reflection spectrum is minimized based on the frequency-specific RF reflection spectrum acquired in (c2); and (c4) setting the frequency band of the third modulated RF signal output from the RF generator such that the center frequency of the said frequency band becomes the target frequency. A plasma processing device including Claim 6 A plasma processing apparatus according to any one of claims 1 to 5, wherein the RF reflection characteristic is any one of (a) the ratio or proportion [%] of the power of the propagating wave to the power of the reflected wave at the node, (b) the resistance component [Ω] of the impedance, (c) the reflection coefficient, (d) the return loss [dB], and (e) the S parameter [dB]. Claim 7 A plasma processing apparatus according to any one of claims 1 to 5, further comprising an impedance matching circuit connected between the chamber and the measuring instrument. Claim 8 A plasma processing apparatus according to any one of claims 1 to 5, further comprising an impedance matching circuit connected between the RF generating unit and the measuring instrument. Claim 9 A plasma processing apparatus according to any one of claims 1 to 5, wherein the RF generating unit comprises a waveform output unit configured to output a broadband RF signal having a plurality of superimposed frequency components, and a power amplifier configured to amplify the broadband RF signal and output a modulated RF signal including a plurality of frequency components. Claim 10 A plasma processing apparatus according to any one of claims 1 to 5, wherein the RF generating unit comprises a waveform output unit configured to sequentially output sweep RF signals having different frequencies, and a power amplifier configured to sequentially amplify the sweep RF signals to output a modulated RF signal including a plurality of frequency components. Claim 11 A plasma processing apparatus according to any one of claims 1 to 5, wherein the power level at which the plasma is not generated is less than 10W. Claim 12 A plasma processing apparatus according to any one of claims 1 to 5, wherein the first frequency band has a bandwidth of less than 20% of the design frequency of the RF generating unit, and the second frequency band has a bandwidth of less than 10% of the design frequency. Claim 13 A plasma processing apparatus according to claim 4 or 5, wherein the target width is within the range of 0.1 to 1% of the design frequency of the RF generating unit. Claim 14 A plasma processing apparatus according to claim 4 or 5, wherein in (b5), the frequency band of the modulated RF signal is narrowed from 0.1 kHz to 500 kHz. Claim 15 The apparatus comprises a chamber, an antenna disposed above the chamber, an RF generator connected to the antenna, a measuring device configured to detect RF reflection characteristics at a node between the antenna and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma maintenance sequence for maintaining a plasma generated within the chamber, wherein the plasma maintenance sequence comprises: (c1) controlling the RF generator to output a third modulated RF signal having a plurality of frequency components and a fourth modulated RF signal having a plurality of frequency components, wherein the third modulated RF signal has a power level capable of generating plasma in the chamber, the fourth modulated RF signal has a power level such that plasma is not generated in the chamber, and the frequency band of the fourth modulated RF signal is wider than the frequency band of the third modulated RF signal; (c2) acquiring an RF reflection spectrum for each frequency corresponding to the third modulated RF signal and the fourth modulated RF signal from the analyzer; and (c3) the RF reflection spectrum for each frequency acquired in (c2). A plasma processing apparatus comprising determining a target frequency at which the RF reflection spectrum is minimized based on the RF reflection spectrum, and (c4) setting the frequency band of the third modulated RF signal output from the RF generation unit such that the center frequency of the frequency band becomes the target frequency. Claim 16 The apparatus comprises an RF generator coupled to a chamber, a measuring device configured to detect RF reflection characteristics at a node between the chamber and the RF generator, an analyzer configured to determine an RF reflection spectrum for each frequency based on the RF reflection characteristics, and a control unit configured to execute a plasma ignition sequence, wherein the plasma ignition sequence comprises: (a1) controlling the RF generator to output a first modulated RF signal having a plurality of frequency components in a first frequency band, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber; (a2) acquiring an RF reflection spectrum for each frequency of the first modulated RF signal from the analyzer; (a3) ​​determining an ignition frequency based on the RF reflection spectrum for each frequency acquired in (a2); and (a4) controlling the RF generator to output a second modulated RF signal having a plurality of frequency components in a second frequency band, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal is capable of generating plasma in the chamber. RF system including having a power level. Claim 17 A plasma processing method comprising: a process of outputting a first modulated RF signal having multiple frequency components in a first frequency band to a chamber, wherein the first modulated RF signal has a power level such that plasma is not generated in the chamber; a process of detecting RF reflection characteristics from the chamber; a process of acquiring an RF reflection spectrum for each frequency corresponding to the first modulated RF signal based on the acquired RF reflection characteristics; a process of determining an ignition frequency based on the acquired RF reflection spectrum for each frequency; and a process of outputting a second modulated RF signal having multiple frequency components in a second frequency band to the chamber, wherein the second frequency band includes the ignition frequency and is a band narrower than the first frequency band, and the second modulated RF signal has a power level capable of generating plasma in the chamber.

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