Plasma processing device

Abstract

Provided is a plasma processing device for efficiently performing plasma processing. The plasma processing device comprises: a chamber; a substrate support part that is disposed in the chamber and includes a lower electrode; an upper electrode that is disposed above the substrate support part; an RF signal generator that is electrically connected to the upper electrode or the lower electrode and is configured to generate an RF signal for generating plasma in the chamber; a first voltage signal generator that is electrically connected to the lower electrode and is configured to generate a first voltage signal having a sequence of first voltage pulses; a second voltage signal generator that is electrically connected to the upper electrode, that is configured to generate a second voltage signal, that includes a rectifier element electrically connected between a ground potential and the upper electrode, and that includes a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the upper electrode; one or more sensors that are configured to monitor the state of the plasma in the chamber; and a control unit that is configured to control a waveform of the second voltage signal on the basis of an output of the one or more sensors.

Description

Plasma processing apparatus

[0001] The present disclosure relates to a plasma processing apparatus.

[0002] Patent Documents 1 and 2 disclose techniques related to phase control of the upper voltage.

[0003] U.S. Patent Application Publication No. 2022 / 0399183, U.S. Patent Application Publication No. 2022 / 0399186

[0004] The present disclosure provides a plasma processing apparatus for efficiently performing plasma processing.

[0005] A plasma processing apparatus according to an exemplary embodiment of the present disclosure includes a chamber, a substrate support portion disposed in the chamber and including a lower electrode, an upper electrode disposed above the substrate support portion, an RF signal generator electrically connected to the upper electrode or the lower electrode and configured to generate an RF signal for generating plasma in the chamber, a first voltage signal generator electrically connected to the lower electrode and configured to generate a first voltage signal having a sequence of first voltage pulses, and a second voltage signal generator electrically connected to the upper electrode and configured to generate a second voltage signal. The second voltage signal generator includes a rectifying element electrically connected between the ground potential and the upper electrode, and a voltage phase adjustment element electrically connected in series with the rectifying element between the ground potential and the upper electrode. The plasma processing apparatus further includes one or more sensors configured to monitor the state of the plasma in the chamber, and a control unit configured to control the waveform of the second voltage signal based on the output of the one or more sensors.

[0006] According to an exemplary embodiment of the present disclosure, a plasma processing apparatus for efficiently performing plasma processing can be provided.

[0007] This is a diagram illustrating an example of the configuration of a plasma processing system. This is a diagram illustrating an example of the configuration of a plasma processing system. This is a diagram illustrating an example of a voltage pulse according to this embodiment. This is a diagram illustrating an example of a voltage pulse according to this embodiment. This is a diagram illustrating an example of a voltage pulse according to this embodiment. This is a diagram illustrating an example of a voltage pulse according to this embodiment. This is a diagram illustrating a second voltage generation unit according to the first embodiment. This is a diagram illustrating a second voltage generation unit according to the first embodiment. This is a diagram illustrating a second voltage generation unit according to the third embodiment. This is a diagram illustrating a second voltage generation unit according to the third embodiment. This is a diagram illustrating a second voltage generation unit according to the third embodiment. This is a diagram illustrating a second voltage generation unit according to the fourth embodiment. This is a diagram illustrating a second voltage generation unit according to the fourth embodiment. This is a diagram illustrating a second voltage generation unit according to the fourth embodiment. This is a diagram illustrating a second voltage generation unit according to the fifth embodiment. This is a diagram illustrating a second voltage generation unit according to the fifth embodiment. This is a diagram illustrating a second voltage generation unit according to the sixth embodiment. This is a diagram illustrating an example configuration of the control unit 2. This is a diagram illustrating an example configuration of the control unit 2. This is a diagram illustrating an example operation of the control unit 2. This is a diagram illustrating an example operation of the control unit 2. This is a diagram illustrating an example operation of the control unit 2. This is a diagram illustrating an example operation of the control unit 2. This is a diagram illustrating an example operation of the control unit 2. This is a diagram illustrating an example operation of the control unit 2. This is a diagram illustrating another example configuration of the plasma processing system.

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, a plasma processing apparatus is provided, comprising: a chamber; a substrate support portion disposed within the chamber and including a lower electrode; an upper electrode disposed above the substrate support portion; an RF signal generator electrically connected to the upper or lower electrode and configured to generate an RF signal for generating plasma in the chamber; a first voltage signal generator electrically connected to the lower electrode and configured to generate a first voltage signal having a first sequence of voltage pulses; a second voltage signal generator electrically connected to the upper electrode and configured to generate a second voltage signal, wherein the second voltage signal generator includes a rectifier element electrically connected between the ground potential and the upper electrode, and a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the upper electrode; one or more sensors configured to monitor the state of the plasma in the chamber; and a control unit configured to control the waveform of the second voltage signal based on the output of one or more sensors.

[0010] In one exemplary embodiment, one or more sensors include a sensor configured to output a measurement value relating to the lower electrode.

[0011] In one exemplary embodiment, one or more sensors include a sensor configured to output a measurement value relating to a second voltage signal.

[0012] In one exemplary embodiment, one or more sensors include sensors installed within a chamber.

[0013] In one exemplary embodiment, one or more sensors include sensors configured to output measurements relating to a matching circuit electrically connected to an RF signal generator.

[0014] In one exemplary embodiment, one or more sensors include sensors configured to output measurements relating to at least one of the emission of plasma within a chamber and electromagnetic waves.

[0015] In one exemplary embodiment, the voltage phase adjustment element includes a variable inductor, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

[0016] In one exemplary embodiment, the voltage phase adjustment element includes a variable inductor and a capacitor connected in series, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

[0017] In one exemplary embodiment, the control unit is configured to control the output of an RF signal generator based on the output of one or more sensors.

[0018] In one exemplary embodiment, the second voltage signal generator further comprises a rectifier current circuit electrically connected between the upper electrode and ground potential and in parallel with the rectifier element, the rectifier current circuit including a variable resistor and a high-frequency cut-off element connected in series, and the control unit is configured to control the variable resistor based on the output of one or more sensors.

[0019] In one exemplary embodiment, the second voltage signal generator further comprises a regulating circuit electrically connected between the upper electrode and ground potential and in parallel with the rectifier element, the regulating circuit including a variable capacitor, and a control unit configured to control the variable capacitor based on the output of one or more sensors.

[0020] In one exemplary embodiment, the second voltage signal generator further comprises a regulating circuit electrically connected between the upper electrode and ground potential and in parallel with the rectifier element, the regulating circuit including a variable inductor, and a control unit configured to control the variable inductor based on the output of one or more sensors.

[0021] In one exemplary embodiment, the plasma processing apparatus according to claim 1, further comprising: an offset voltage generator electrically connected between the upper electrode and ground potential and in parallel with a rectifier element and configured to offset the voltage generated at the upper electrode; a rectifier current circuit electrically connected between the upper electrode and ground potential and in parallel with a rectifier element; and a capacitor electrically connected between the offset voltage generator and the rectifier current circuit, wherein the control unit is configured to control the output of the offset voltage generator based on the output of one or more sensors.

[0022] In one exemplary embodiment, a plasma processing apparatus is provided, comprising: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber and including electrodes; a first voltage signal generator electrically connected to the electrodes and configured to generate a first voltage signal having a sequence of first voltage pulses; a conductive member constituting part of the plasma processing chamber or disposed within the plasma processing chamber; a second voltage signal generator electrically connected to the conductive member and configured to generate a second voltage signal, wherein the second voltage signal generator includes a rectifier element electrically connected between the ground potential and the conductive member, and a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the conductive member; one or more sensors configured to monitor the state of the plasma in the plasma processing chamber; and a control unit configured to control the waveform of the second voltage signal based on the output of one or more sensors.

[0023] In one exemplary embodiment, one or more sensors include sensors configured to output measurements relating to electrodes.

[0024] In one exemplary embodiment, one or more sensors include a sensor configured to output a measurement value relating to a second voltage signal.

[0025] In one exemplary embodiment, one or more sensors include sensors installed within a plasma processing chamber.

[0026] In one exemplary embodiment, one or more sensors include sensors configured to output measurements relating to at least one of the emission of plasma and electromagnetic waves within a plasma processing chamber.

[0027] In one exemplary embodiment, the voltage phase adjustment element includes an inductor and a variable capacitor connected in series, and the control unit is configured to control the variable capacitor based on the output of one or more sensors.

[0028] In one exemplary embodiment, the control unit is configured to control the output of an RF signal generator based on the output of one or more sensors.

[0029] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, left, and right will be 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 those shown.

[0030] <Example of a Plasma Processing System> Figure 1 is a diagram illustrating an example of the configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 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. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0031] 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 capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR (Electron Cyclotron Resonance) plasma, helicon wave excited plasma (HWP), or surface wave plasma (SWP), etc. Various types of plasma generation units, including AC (Alternating Current) plasma generation units and DC (Direct Current) plasma generation units, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 300 MHz.

[0032] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control the elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions realized by the processing unit 2a1 described herein may be implemented in a circuit or processing circuit, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), a conventional circuit, and / or a combination thereof, programmed to realize the described functions. The processor is considered to be a circuit or processing circuit, including transistors and other circuits. The processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. 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 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0033] The following describes an example configuration of a capacitively coupled plasma processing apparatus as an example of a plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of a capacitively coupled plasma processing apparatus.

[0034] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the side walls 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0035] 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 the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0036] 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 lower electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members 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 placed on the annular electrostatic chuck or the annular insulating member, or it may be placed on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, which is electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed inside the ceramic member 1111a. In this case, at least one bias electrode functions as a lower electrode. Also, the conductive member of the base 1110 and the bias electrode inside the ceramic member 1111a may function as multiple lower electrodes. In one embodiment, the first voltage generation unit 32a, which functions as a voltage pulse generation unit described later, is electrically connected or coupled to the bias electrode inside the ceramic member 1111a, and the first RF generation unit 31a, described later, is electrically connected or coupled to the conductive member of the base 1110. Furthermore, the electrostatic chuck electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0037] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0038] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the 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 arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0039] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlet ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0040] 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 to the shower head 13 from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of at least one processing gas.

[0041] The power supply system 30 includes a power supply 31 that is electrically connected to or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected to or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least part of the plasma generation unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ionic components in the formed plasma can be drawn into the substrate W.

[0042] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matcher. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 300 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0043] The second RF generation unit 31b is electrically connected or coupled to at least one lower electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected or coupled to at least one lower electrode via at least one impedance matcher. When the first RF generation unit 31a is electrically connected or coupled to the lower electrode, the second RF generation unit 31b may be electrically connected or coupled to the same lower electrode or may be electrically connected or coupled to another lower electrode. 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. The generated one or more bias RF signals are supplied to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0044] Also, the power supply system 30 may include a power supply 32 that is electrically connected or coupled to the plasma processing chamber 10. The power supply 32 includes a first voltage generation unit 32a and a second voltage generation unit 32b. In one embodiment, the first voltage generation unit 32a is electrically connected or coupled to at least one lower electrode and is configured to generate a first voltage signal. The generated first voltage signal is applied to at least one lower electrode. In one embodiment, the second voltage generation unit 32b is electrically connected or coupled to at least one upper electrode and is configured to generate a second voltage signal. The generated second voltage signal is applied to at least one upper electrode.

[0045] In various embodiments, the first and / or second voltage signals may be pulsed. In this case, the first voltage generation unit 32a and / or the second voltage generation unit 32b function as voltage pulse generation units configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. In one embodiment, the sequence of voltage pulses has a plurality of cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, in the sequence of voltage pulses, the burst of voltage pulses is repeated. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangle, trapezoid, triangle, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive polarity or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. The first and second voltage generation units 32a and 32b may be provided in addition to the power supply 31, and the first voltage generation unit 32a may be provided in place of the second RF generation unit 31b.

[0046] The exhaust system 40 may be connected to, for example, a gas outlet 10e located 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 regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0047] <Example of the First Voltage Signal and the Second Voltage Signal>FIGS. 3A to 3D are timing charts showing an example of the voltage waveforms of the first voltage signal and the second voltage signal. In one embodiment, the voltage waveforms of the first voltage signal and the second voltage signal may be repeated a plurality of times in a repetition period T (see FIGS. 3A to 3D). In one example, the first voltage signal may have a repetition frequency (1 / T) of 0.1 kHz to 50 kHz. In one example, the second voltage signal may have a repetition frequency (1 / T) of 0.1 kHz to 50 kHz. The repetition frequency of the first voltage signal and the repetition frequency of the second voltage signal may be the same or different. The first voltage signal and the second voltage signal may be synchronized (see FIGS. 3A to 3C), or may not be synchronized. For example, the first voltage signal and the second voltage signal may have a phase shift of a given value (180 degrees in one example).

[0048] FIG. 3A is an example in which both the first voltage signal (DC1) and the second voltage signal (DC2) are pulsed. The first voltage signal and the second voltage signal may be generated by a first waveform generation unit and a second waveform generation unit, respectively. In one embodiment, the first voltage signal has a sequence of first voltage pulses having a first voltage level V11 during a first period T1 within the repetition period T. In one example, the sequence of the first voltage pulses may have a pulse frequency of 0.1 MHz to 2 MHz (hereinafter, a voltage pulse having such a pulse frequency is also referred to as a "high-speed pulse"). The first voltage signal has a reference voltage level V10 during a second period T2 within the repetition period T. The absolute value of the reference voltage level V10 is smaller than the absolute value of the first voltage level V11. In one embodiment, the first voltage level V11 has a negative polarity. In one embodiment, the reference voltage level V10 has a zero voltage level.

[0049] The second voltage signal (DC2) has a sequence of second voltage pulses having a second voltage level V21 during a first period T1. In one example, the sequence of second voltage pulses may have a pulse frequency of 0.1 MHz to 2 MHz. The pulse frequency of the sequence of second voltage pulses may be the same as or different from the pulse frequency of the sequence of first voltage pulses. The second voltage signal also has a reference voltage level V20 during a second period T2. The reference voltage level V20 is smaller than the absolute value of the second voltage level V21. In one embodiment, the second voltage level V21 has negative polarity. In one embodiment, the reference voltage level V20 has a zero voltage level.

[0050] Figure 3B shows a modified version of the voltage waveform shown in Figure 3A. The first voltage signal (DC1) and the second voltage signal (DC2) may be generated by the first waveform generation unit and the second waveform generation unit, respectively. Both the first and second voltage signals are pulsed. In this example, the first voltage signal has a sequence of third voltage pulses having a third voltage level V12 during a second period T2 within the repetition period T. The absolute value of the third voltage level V12 is greater than the absolute value of the reference voltage level V10 and less than the absolute value of the first voltage level V11. The sequence of third voltage pulses may have a pulse frequency of 0.1 MHz to 2 MHz. The second voltage signal also has a sequence of fourth voltage pulses having a fourth voltage level V22 during a second period T2 within the repetition period T. The absolute value of the fourth voltage level V22 is greater than the absolute value of the reference voltage level V20 and less than the absolute value of the second voltage level V21. The sequence of fourth voltage pulses may have pulse frequencies between 0.1 MHz and 2 MHz. The remaining aspects are the same as in the example shown in Figure 3A. In the example shown in Figure 3B, the repetition period T may further have a third period T3. The first voltage signal may have a reference voltage level V10 during the third period T3 within the repetition period T. The second voltage signal may have a reference voltage level V20 during the third period T3 within the repetition period T.

[0051] Figure 3C shows a modified version of the voltage waveform shown in Figure 3A. Both the first voltage signal (DC1) and the second voltage signal (DC2) are pulsed. The first voltage signal may be generated by the first waveform generation unit. The second voltage signal may be generated by the second waveform generation unit (including cases where it is integrally configured with the second voltage generation unit 32b), or it may be generated by the second voltage generation unit 32b. In this example, the second voltage signal has a sequence of second voltage pulses in a repetition period T. That is, the sequence of second voltage pulses in this example has a second voltage level V21 during the first period T1 and a reference voltage level V20 during the second period T2. The pulse frequency of the sequence of second voltage pulses may be the same as the repetition frequency (1 / T) of the first voltage signal, and may be, for example, 0.1 kHz to 50 kHz (hereinafter, voltage pulses with such pulse frequencies are also referred to as "low-speed pulses"). The remaining points may be the same as in the example shown in Figure 4A.

[0052] In the example shown in Figure 3C, when the first voltage signal is at the first voltage level V11, the second voltage signal is at the second voltage level V21, and when the first voltage signal is at the reference voltage level V10, the second voltage signal is also at the reference voltage level V20. However, when the first voltage signal is at the first voltage level V11, the second voltage signal may be at the reference voltage level V20, and when the first voltage signal is at the reference voltage level V10, the second voltage signal may be at the second voltage level V21.

[0053] Figure 3D shows a modified version of the voltage waveform shown in Figure 3A. In this example, only the first voltage signal (DC1) is pulsed, and the second voltage signal has a constant voltage level (second voltage level V21) during the first period T1 and the second period T2 within the repetition period T. The second voltage signal may be generated by the second voltage generation unit 32b. The remaining aspects may be the same as in the example shown in Figure 3A.

[0054] In one example, the first voltage signal can cause positive charge to accumulate in holes on the wafer. At this time, the potential on the wafer may be positively offset. One example of the role of the second voltage signal is to neutralize this positive charge. However, if the first voltage signal is a high-speed pulse and the second voltage signal is a low-speed pulse, the neutralization of the positive charge may be insufficient for part of the period during which the first voltage signal is applied. Also, if both the first and second voltage signals are high-speed pulses, the neutralization of the positive charge may be insufficient due to the influence of the first voltage signal on the waveform shape of the second voltage signal. The second voltage generation unit 32b of this embodiment can solve the problems described in this example with a simple configuration and low power consumption.

[0055] <Example of the second voltage generation unit 32b> (First embodiment) The second voltage generation unit 32b according to the first embodiment will be described with reference to Figures 4 and 5. Figure 4 is a diagram for illustrating an example of the configuration of the second voltage generation unit 32b according to the first embodiment. In Figure 4, the plasma processing chamber 10 shown in Figure 2 is shown in a simplified form. That is, Figure 4 shows the shower head 13 and base 1110 inside the plasma processing chamber 10. The shower head 13 is equipped with an upper electrode UE. The base 1110 is equipped with a lower electrode BE. The first voltage generation unit 32a is electrically connected to the lower electrode BE. The second voltage generation unit 32b is electrically connected to the upper electrode UE.

[0056] The second voltage generation unit 32b includes a voltage phase adjustment element 32bP and a rectifier element 32bD1. The rectifier element 32bD1 is electrically connected between the ground potential and the upper electrode UE. The voltage phase adjustment element 32bP is electrically connected between the rectifier element 32bD1 and the upper electrode UE.

[0057] In one embodiment, the voltage phase adjustment element 32bP is an element for adjusting the phase of a voltage. In one example, the voltage phase adjustment element 32bP includes an inductor 32bL1. In this case, the inductance of the inductor 32bL1 is, for example, 1 μH to 200 μH. As will be described in detail later, the voltage phase adjustment element 32bP may further include a capacitor 32bC1 connected in series with the inductor 32bL1.

[0058] In one embodiment, the rectifier element 32bD1 is an element that controls the direction of current flow. In one example, the rectifier element 32bD1 is a PN junction diode. When the rectifier element 32bD1 is a diode, the diode may be of mesa type or planar type. In one embodiment, the rectifier element 32bD1 comprises an anode and a cathode. In one embodiment, as shown in Figure 4, the cathode side of the rectifier element 32bD1 is electrically connected to ground potential.

[0059] The second voltage generation unit 32b outputs a second voltage signal in response to the first voltage signal output by the first voltage generation unit 32a. Figure 5 is a conceptual diagram showing an example of the relationship between the first voltage signal (DC1) and the second voltage signal (DC2). The first voltage signal generated by the first voltage generation unit 32a has multiple peaks. In contrast, the second voltage signal generated by the second voltage generation unit 32b has multiple first peaks and multiple second peaks.

[0060] Multiple first peaks in the second voltage signal are generated by the first voltage signal. Specifically, the first voltage signal output from the lower electrode BE acts on the second voltage generation unit 32b via the upper electrode UE. This causes the first peaks to form in the second voltage signal.

[0061] In contrast, the multiple second peaks are generated by current and voltage oscillations in the second voltage generation unit 32b. Specifically, the second peaks are formed during the transition of the second voltage generation unit 32b from a state in which the first peak is generated in the second voltage signal to a steady state.

[0062] This configuration makes it possible to generate a second voltage signal having the same period as the first voltage signal. That is, the positive charge in the hole generated by the peak of the first voltage signal can be neutralized by the second peak of the second voltage signal that occurs immediately after the peak of the first voltage signal. This makes it possible to achieve at least one of the following: for example, increasing the density of the plasma in the chamber 10, neutralizing the positive charge in the hole with electrons emitted from the upper electrode UE, and suppressing unintended offsets of the potential on the wear. Furthermore, with this configuration, since the second voltage signal is generated using the power of the first voltage signal, it may be unnecessary to supply power to the second voltage generation unit 32b with a separate power supply.

[0063] (Second Embodiment) The second voltage generation unit 32b according to the second embodiment will be described with reference to Figures 6 to 8. Compared with the second voltage generation unit 32b according to the first embodiment (see Figure 4), the second voltage generation unit 32b according to the third embodiment has one or more elements electrically connected between the ground potential and the rectifier element 32bD1.

[0064] In one embodiment, the one or more elements include a capacitor. Figure 6 shows an example configuration in which a capacitor 32bC1 is electrically connected between the ground potential and the rectifier element 32bD1.

[0065] Figure 7 illustrates an example of the waveform of the second voltage signal when a capacitor 32bC1 is electrically connected between the ground potential and the rectifier element 32bD1. The dotted line in Figure 7 shows an example of the waveform of the second voltage signal when the capacitor 32bC1 is not inserted. The solid line in Figure 7 shows an example of the waveform of the second voltage signal when a capacitor 32bC1 is inserted between the rectifier element 32bD1 and the ground potential. Comparing the dotted line and the solid line in Figure 7, it can be seen that the amplitude of the second peak is reduced by inserting the capacitor 32bC1.

[0066] In one embodiment, the one or more elements include at least one of a resistor and a transformer. Figure 8 shows an example configuration of a second voltage generating unit 32b in which a resistor 32bR1 is electrically connected between the ground potential and the rectifier element 32bD1. With this configuration, the resistor 32bR1 can be used as a voltage and current monitor. Although Figure 8 shows an example configuration in which a resistor 32bR1 is used, a transformer can be used in the same way.

[0067] (Third Embodiment) The second voltage generation unit 32b according to the third embodiment will be described with reference to Figures 9 and 10. Figure 9 is a diagram showing an example of the configuration of the second voltage generation unit 32b according to the fourth embodiment. Compared to the second voltage generation unit 32b according to the first embodiment (see Figure 4), the second voltage generation unit 32b according to the fourth embodiment further includes a rectifier current circuit 32b1.

[0068] The rectifier current circuit 32b1 is electrically connected between the upper electrode UE and the ground potential, and in parallel with the rectifier element 32bD1. In one embodiment, the rectifier current circuit 32b1 is electrically connected between the node between the rectifier element 32bD1 and the voltage phase adjustment element 32bP, and the ground potential.

[0069] In this disclosure, the fact that element A is electrically connected in parallel with element B includes the existence of a first path from the upper electrode UE to the ground potential, passing through element A without passing through element B, and a second path from the upper electrode UE to the ground potential, passing through element B without passing through element A.

[0070] In one embodiment, the rectifier current circuit 32b1 includes a high-frequency blocking element 32bL2 and a resistor 32bR2. The high-frequency blocking element 32bL2 and the resistor 32bR2 are electrically connected in series.

[0071] The high-frequency cut-off element 32bL2 may be an element for attenuating high-frequency current (in one example, a current of 100 kHz or higher). In one embodiment, the high-frequency cut-off element 32bL2 is at least one of an inductor and a filter circuit. The filter circuit is, for example, a low-pass filter including a resistor and a capacitor, a low-pass filter including an operational amplifier, or a low-pass filter including an inductor and a capacitor. When the high-frequency cut-off element 32bL2 is an inductor, the inductance of the inductor may be, for example, 100 μH to 2 mH. In one example, the frequency band to be attenuated by the high-frequency cut-off element 32bL2 may be determined in advance by the user of the plasma processing apparatus 1 (for example, at the time of determining the recipe). Furthermore, by providing the high-frequency cut-off element 32bL2, the degree of freedom in the insertion position of the rectifier current circuit 32b1 can be improved.

[0072] The resistor 32bR2 can be an element used to weaken the effect of the rectifier element 32bD1. That is, by adjusting the resistance value of resistor 32bR2, the peak voltage in the second voltage signal can be adjusted. Furthermore, resistor 32bR2 can stabilize the rectification effect when a capacitor is present between the upper electrode UE and the rectifier element 32bD1. The resistance value of resistor 32bR2 can be, for example, 1Ω to 1000Ω.

[0073] According to the rectifier current circuit 32b1, even if a sheath is generated inside the plasma processing chamber 10, the rectified current can be supplied stably regardless of fluctuations in the sheath.

[0074] Figure 10 shows another configuration example of the second voltage generation unit 32b according to the third embodiment. In Figure 10, the rectifier element 32bD1 is grounded on the anode side. Figure 11 is a diagram illustrating an example of the waveform of the second voltage signal output by the second voltage generation unit 32b according to the third embodiment. The solid line shows an example of the waveform of the second voltage signal when the rectifier element 32bD1 is grounded on the cathode side. The dotted line shows an example of the waveform of the second voltage signal when the rectifier element 32bD1 is grounded on the anode side. The phase of the second peak (i.e., the time width with the first peak) when the rectifier element 32bD1 is grounded on the cathode side is different from the phase of the second peak when the rectifier element 32bD1 is grounded on the anode side. In other words, according to the second voltage generation unit 32b according to the third embodiment, the phase of the second peak can be adjusted depending on whether the rectifier element 32bD1 is grounded on the anode side or the cathode side. Furthermore, when the rectifier element 32bD1 is grounded at the anode, the voltage waveform exhibits a positive offset voltage compared to the voltage waveform when the rectifier element 32bD1 is grounded at the kanode. This offset voltage can be canceled out, for example, by an offset voltage generator 32bV1, which will be described later.

[0075] Figure 12 shows another example of the configuration of the second voltage generation unit 32b according to the third embodiment. In the example in Figure 12, the rectifier current circuit 32b1 is electrically connected between the node between the upper electrode UE and the voltage phase adjustment element 32bP, and between the ground potential.

[0076] (Fourth Embodiment) The second voltage generation unit 32b according to the fourth embodiment will be described with reference to Figures 13 to 16. Figure 13 is a diagram showing an example of the configuration of the second voltage generation unit 32b according to the fourth embodiment. The second voltage generation unit 32b according to the fifth embodiment further comprises an adjustment circuit 32b2 compared to the second voltage generation unit 32b according to the third embodiment (see Figure 9). The adjustment circuit 32b2 is electrically connected between the upper electrode UE and the ground potential, and in parallel with the rectifier element 32bD1. The adjustment circuit 32b2 includes at least one of a capacitor and an inductor. In one embodiment, the adjustment circuit 32b2 is electrically connected between the node between the voltage phase adjustment element 32bP and the rectifier element 32bD1, and the ground potential, as shown in Figure 13. That is, the adjustment circuit 32b2 may be provided in direction B with respect to the voltage phase adjustment element 32bP. Figure 13 shows an example in which the adjustment circuit 32b2 is configured using a capacitor.

[0077] Figure 14 is a diagram illustrating an example of the waveform of a second voltage signal according to the fourth embodiment. The solid line in Figure 14 shows the second voltage signal generated by the second voltage generation unit 32b without the adjustment circuit 32b2 (i.e., the second voltage generation unit 32b according to the third embodiment). The dotted line in Figure 14 shows the second voltage signal generated by the second voltage generation unit 32b with the adjustment circuit 32b2. Comparing the solid and dotted lines in Figure 14, it can be seen that the amplitude of the second peak changes when the adjustment circuit 32b2 is provided.

[0078] Figure 15 is a diagram illustrating other waveform examples of the second voltage signal according to the fourth embodiment. The solid line in Figure 15 shows the second voltage signal from the second voltage generation unit 32b when the adjustment circuit 32b2 is configured with a capacitor having a relatively small capacitance. The dotted line in Figure 15 shows the second voltage signal from the second voltage generation unit 32b when the adjustment circuit 32b2 is configured with a capacitor having a relatively large capacitance. As can be seen from Figure 15, when the adjustment circuit 32b2 is configured with a capacitor, the amplitude of the second voltage signal differs depending on its capacitance.

[0079] In one embodiment, the adjustment circuit 32b2 is composed of an inductor (without a capacitor). In another embodiment, the adjustment circuit 32b2 is electrically connected between the node between the upper electrode UE and the voltage phase adjustment element 32bP, and the ground potential. That is, the adjustment circuit 32b2 may be provided in direction A with respect to the voltage phase adjustment element 32bP. Figure 16 is a diagram illustrating other waveform examples of the second voltage signal according to the fourth embodiment. The solid line in Figure 16 shows the second voltage signal from the second voltage generation unit 32b when the adjustment circuit 32b2 is composed of an inductor with relatively large inductance, and the adjustment circuit 32b2 is provided in direction A with respect to the voltage phase adjustment element 32bP. The dotted line in Figure 16 shows the second voltage signal from the second voltage generation unit 32b when the adjustment circuit 32b2 is composed of an inductor with relatively small inductance, and the adjustment circuit 32b2 is provided in direction A with respect to the voltage phase adjustment element 32bP. As can be seen from Figure 16, when the adjustment circuit 32b2 is composed of an inductor, the number of peaks per unit period of the second voltage signal differs depending on the inductor.

[0080] In another embodiment, the adjustment circuit 32b2 is configured by electrically connecting a capacitor and an inductor in series.

[0081] (Fifth Embodiment) Figure 17 shows an example of the configuration of the second voltage generation unit 32b according to the fifth embodiment. The second voltage generation unit 32b according to the sixth embodiment further includes an offset voltage generator 32bV1 compared to the second voltage generation unit 32b according to the third embodiment (see Figure 9). In addition, the voltage phase adjustment element 32bP according to the fifth embodiment further includes a capacitor 32bC1 connected in series with the inductor 32bL1, in addition to the inductor 32bL1. The offset voltage generator 32bV1 is electrically connected between the upper electrode UE and the ground potential, and in parallel with the rectifier element 32bD1. The offset voltage generator 32bV1 is configured to offset the voltage generated at the upper electrode UE. The capacitor 32bC1 constitutes part of the voltage phase adjustment element 32bP by being electrically connected between the offset voltage generator 32bV1 and the inductor 32bL1.

[0082] In one embodiment, the offset voltage generator 32bV1 is configured to generate voltage pulses having a frequency lower than the frequency of the sequence of first voltage pulses output by the first voltage generation unit 32a. In another embodiment, the offset voltage generator 32bV1 is configured to output a constant DC voltage.

[0083] In one embodiment, the offset voltage generator 32bV1 is configured to output a voltage of less than 1000V. The offset voltage generator 32bV1 may output a positive voltage or a negative voltage.

[0084] <Example of operation of control unit 2> The plasma processing apparatus 1 is equipped with one or more sensors, and the control unit 2 can control the operation of the plasma processing apparatus 1 based on the output of each of the one or more sensors. In one embodiment, the control unit 2 controls the waveform of a second voltage signal.

[0085] Figure 18 shows another example of the configuration of the plasma processing system. The plasma processing apparatus 1 in Figure 18 includes, in addition to the configuration shown in Figure 2, an impedance matching device 31M and sensors S1 to S5. Also, in the example in Figure 18, the inductor 32bL1, high-frequency cut-off element 32bL2, resistor 32bR2, and offset voltage generator 32bV1 are all made up of variable elements.

[0086] Sensors S1 to S5 are configured to output measured values ​​relating to the state and / or generation of plasma in the plasma processing chamber 10. The impedance matcher 31M is electrically connected to the first RF generation unit 31a and the second RF generation unit 31b. The impedance matcher 31M is further electrically connected to the lower electrode BE.

[0087] In one embodiment, the sensor S1 is electrically connected between the impedance matcher 31M and the lower electrode BE. The sensor S1 is configured to output a measurement value relating to the lower electrode BE. The measurement value relating to the lower electrode BE includes, for example, information regarding the voltage waveform and / or current waveform output from the impedance matcher 31M to the lower electrode BE. The sensor S1 may be housed in a common housing with the impedance matcher 31M, or it may be housed in a separate housing.

[0088] In one embodiment, the sensor S2 is electrically connected between the second voltage generation unit 32b and the upper electrode UE. The sensor S2 is configured to output measured values ​​relating to the second voltage signal. The measured values ​​relating to the second voltage signal include, for example, information regarding the frequency, first peak amplitude, second peak amplitude and phase, and offset voltage of the second voltage signal.

[0089] In one embodiment, the sensor S3 is installed inside the plasma processing chamber 10 and is configured to output measured values ​​related to the state and / or generation of the plasma. The measured values ​​related to the state and / or generation of the plasma output by the sensor S3 include information such as the voltage waveform and / or current waveform inside the plasma processing chamber 10, the phase difference between the voltage waveform and the current waveform, and the plasma density.

[0090] In one embodiment, the sensor S4 is electrically connected to the impedance matcher 31M. The sensor S4 is configured to output measured values ​​related to the impedance matcher 31M. The measured values ​​related to the impedance matcher 31M include the voltage waveform (including VPP (Voltage peak to peak)) and / or current waveform of the RF signal generated by the first RF generation unit 31a, the voltage waveform and / or current waveform of the RF signal generated by the second RF generation unit 31b, and information regarding the degree of matching, etc.

[0091] In one embodiment, the sensor S5 is configured to output measured values ​​relating to at least one of the plasma emission and electromagnetic waves within the plasma processing chamber 10. The measured values ​​relating to at least one of the plasma emission and electromagnetic waves include information such as the measured wavelength, measured frequency, and pulse height of the plasma.

[0092] In one embodiment, the control unit 2 can function as an acquisition unit 200, a determination unit 202, a decision unit 204, and an instruction unit 206 by executing various programs stored in the storage unit 2a2. Figure 19 shows an example of the relationship between the acquisition unit 200, the determination unit 202, the decision unit 204, and the instruction unit 206.

[0093] (Acquisition Unit 200) In one embodiment, the acquisition unit 200 acquires measured values ​​relating to the state and / or generation of plasma in the plasma processing chamber 10 from at least one of the sensors S1 to S5. The acquisition unit 200 may acquire measured values ​​sequentially or in a batch process manner. When the acquisition unit 200 acquires measured values ​​in a batch process manner, the measured values ​​may be values ​​that have undergone statistical processing such as averaging. In one embodiment, the acquisition unit 200 acquires information relating to the element constants of the variable element of the second voltage generation unit 32b.

[0094] In one embodiment, the acquisition unit 200 may further acquire information regarding voltage and / or current waveforms on the wafer estimated based on the acquired measurements. In one example, the voltage and / or current waveforms on the wafer can be estimated using simulation software for waveform estimation.

[0095] In this disclosure, acquiring information includes making the information available for processing by the control unit 2. That is, acquiring information may involve receiving the information from another device, reading the information from the storage unit 2a2, or obtaining the information as a result of a given process.

[0096] (Determination Unit 202) In one embodiment, the determination unit 202 determines whether or not there is an abnormality in the state and / or generation of the plasma (hereinafter simply referred to as "presence or absence of abnormality") based on the measurement values ​​acquired by the acquisition unit 200. In one embodiment, the determination unit 202 determines whether or not there is an abnormality based on the voltage waveform and / or current waveform on the wafer estimated based on the measurement values ​​acquired by the acquisition unit 200. In one embodiment, the presence or absence of an abnormality includes whether or not an abnormal discharge or its precursor is occurring in the plasma processing chamber 10. That is, the determination unit 202 may determine whether or not an abnormal discharge or its precursor is occurring in the plasma processing chamber 10 based on the measurement values ​​acquired by the acquisition unit 200, or the voltage waveform and / or current waveform on the wafer estimated based on said measurement values.

[0097] In one embodiment, the determination unit 202 determines whether or not there is an abnormality based on whether or not the measured value acquired by the acquisition unit 200 satisfies a given condition for detecting an abnormality. In one embodiment, the determination unit 202 determines whether or not there is an abnormality based on whether or not the voltage waveform and / or current waveform on the wafer estimated based on the measured value acquired by the acquisition unit 200 satisfies a given condition for detecting an abnormality. This condition may include whether or not the measured value acquired by the acquisition unit 200 exceeds a given threshold for detecting an abnormality.

[0098] In one embodiment, the determination unit 202 determines whether or not there is an abnormality by inputting the measured values ​​acquired by the acquisition unit 200 into a machine learning model. In another embodiment, the determination unit 202 determines whether or not there is an abnormality by inputting the voltage waveform and / or current waveform on the wafer estimated based on the measured values ​​acquired by the acquisition unit 200 into a machine learning model. The machine learning model may be configured based on various abnormality detection algorithms (e.g., One Class SVM, Local Outlier Factor, etc.).

[0099] In this disclosure, "abnormality" is not limited to, for example, a state requiring the plasma processing system to be stopped, but also includes "a state different from the desired state set in the recipe." That is, even if the acquisition unit 200 determines that an abnormality exists based on the measured values ​​it has acquired, the plasma processing system may continue to operate as long as the abnormality is within an acceptable range. If the acquisition unit 200 determines that an abnormality exists that is outside an acceptable range based on the measured values ​​it has acquired, the control unit 2 may at least temporarily stop the operation of the plasma processing system.

[0100] (Decision Unit 204) In one embodiment, the decision unit 204 determines the variable element to be controlled and its control amount based on the measurement values ​​acquired by the acquisition unit 200. In one embodiment, the decision unit 204 determines the variable element to be controlled and its control amount based on the voltage waveform and / or current waveform on the wafer estimated based on the measurement values ​​acquired by the acquisition unit 200. In one example, the decision unit 204 may determine, by how much, which of the following should be controlled: the inductance of the inductor 32bL1, the element constant of the high-frequency cut-off element 32bL2, the resistance value of the resistor 32bR2, and the output voltage of the offset voltage generator 32bV1, based on the measurement values ​​acquired by the acquisition unit 200, or the voltage waveform and / or current waveform on the wafer estimated based on said measurement values. The control amount of the variable element determined by the decision unit 204 may be the difference from the element constant at that time, or it may be the value of the element constant itself.

[0101] In one embodiment, the determination unit 204 determines the variable element to be controlled and its control amount when the judgment unit 202 determines that an abnormality exists. In one example, the determination unit 204 determines the variable element to be controlled and its control amount when it determines that the measurement value acquired by the acquisition unit 200 satisfies a given condition for detecting an abnormality. In another example, the determination unit 204 may determine the variable element to be controlled and its control amount when the output of inputting the measurement value acquired by the acquisition unit 200 into a machine learning model indicates the presence of an abnormality.

[0102] In one embodiment, the determination unit 204 refers to a control table to determine the variable element to be controlled and the amount of control it has. In one example, the control table is a table that associates measured values ​​relating to the state and / or generation of the plasma, the variable element to be controlled when the measured value is acquired, and the amount of control it has with the variable element when the measured value is acquired. In another example, the control table is a table that associates information relating to voltage waveforms and / or current waveforms on the wafer, the variable element to be controlled when the information is acquired, and the amount of control it has with the variable element when the information is acquired.

[0103] The control table may be determined, for example, during the trial run of the plasma processing apparatus 1, based on computer simulations, based on user input for the plasma processing apparatus 1, or based on an analytical model. The control table may be determined to maintain a given neutralization index (e.g., the shape of the voltage waveform and / or current waveform on the wafer).

[0104] In one example, if the measurement values ​​acquired by the acquisition unit 200, or the voltage and / or current waveforms on the wafer estimated by those measurements, are determined by the determination unit 202 to be abnormal and indicate insufficient neutralization of the positive charge of the holes, the determination unit 204 may, for example, refer to a control table to determine a variable element and its control amount for strengthening the neutralization. More specifically, the determination unit 204 may determine a variable element and its control amount for achieving, for example, reducing the phase difference between the first and second peaks of the second voltage signal, increasing the amplitude of the second peak, and increasing the offset potential.

[0105] In another example, if the measurement values ​​acquired by the acquisition unit 200, or the voltage and / or current waveforms on the wafer estimated by those measurements, are determined by the determination unit 202 to be abnormal and indicate that the neutralization of positive charges in holes is excessive, the determination unit 204 may, for example, refer to a control table to determine a variable element and its control amount for reducing the neutralization. More specifically, the determination unit 204 may determine a variable element and its control amount for achieving, for example, increasing the phase difference between the first and second peaks of the second voltage signal, decreasing the amplitude of the second peak, and lowering the offset potential (or adjusting it so that the offset is eliminated).

[0106] In another example, if the measurement values ​​acquired by the acquisition unit 200, or the voltage and / or current waveforms on the wafer estimated by those measurements, are determined by the determination unit 202 to be abnormal, and the abnormality is an abnormal discharge in the plasma processing chamber 10 or a precursor thereof, the determination unit 204 may, for example, refer to a control table to determine a variable element and its control amount for suppressing the abnormal discharge. More specifically, the determination unit 204 may determine a variable element and its control amount for achieving, for example, increasing the phase difference between the first and second peaks of the second voltage signal, decreasing the amplitude of the second peak, and lowering the offset potential (or adjusting it so that the offset is eliminated).

[0107] In addition to the processes described above, the determination unit 204 can perform various processes to determine the variable elements to be controlled and the amount of control they have. In one example, the determination unit 204 estimates the DC voltage component and waveform peak value on the wafer based on the measurements acquired by the acquisition unit 200. In another example, the determination unit 204 estimates the plasma density in the plasma processing chamber 10 based on the measurements acquired by the acquisition unit 200.

[0108] (Instruction Unit 206) In one embodiment, the instruction unit 206 instructs a control amount to the variable element of the second voltage generation unit 32b based on the determination by the determination unit 204. That is, the instruction unit 206 can instruct at least one of the inductance of the inductor 32bL1, the element constant of the high-frequency cut element 32bL2, the resistance value of the resistor 32bR2, and the output voltage of the offset voltage generator 32bV1 based on the determination by the determination unit 204. As a result, the instruction unit 206 can control the waveform of the second voltage signal.

[0109] (Example of First Sequence) Figure 20 is a diagram illustrating an example of the first sequence of the control unit 2. The acquisition unit 200 acquires a measurement value related to the lower electrode BE from the sensor S1 (St11). The acquisition unit 200 further acquires a measurement value related to the impedance matcher 31M from the sensor S4 (St12). The measurement value related to the lower electrode BE includes the voltage waveform and / or current waveform detected by the sensor S1. The measurement value related to the impedance matcher 31M includes information on the degree of matching and the voltage waveform and / or current waveform output by the first RF generation unit 31a and the second RF generation unit 31b, respectively.

[0110] Next, the determination unit 202 determines whether or not a given condition for detecting an anomaly is met based on the measurement value acquired by the acquisition unit 200 (St13).

[0111] If the determination unit 202 determines that the condition is met (i.e., if it determines that an abnormality exists), the decision unit 204 determines the variable element to be controlled and its control amount in order to resolve the abnormality (St14). Specifically, the decision unit 204 performs frequency analysis on the measured value and extracts specific frequency components. Next, the decision unit 204 estimates the DC voltage component and pulse height value on the wafer based on the extraction results. Next, the decision unit 204 estimates the plasma density in the plasma processing chamber 10 based on the measured value acquired by the acquisition unit 200. Next, the decision unit 204 determines the variable element to be controlled and its control amount based on the estimated DC voltage component, pulse height value and plasma density on the wafer and a preset control table. The instruction unit 206 instructs the second voltage generation unit 32b to determine the variable element and its control amount (St15).

[0112] Conversely, if the determination unit 202 determines that the given conditions for detecting an abnormality are not met (i.e., it determines that no abnormality exists), the decision unit 204 may decide not to control the variable element, at least at that point.

[0113] The control unit 2 may repeatedly execute a series of control processes (St11 to St15). When the control unit 2 executes control for the second cycle or later, the acquisition unit 200 may further acquire the amount of change in the voltage waveform and / or current waveform on the wafer after the control instruction, the offset amount and attenuation amount of the voltage waveform and / or current waveform on the wafer, the amount of change in the voltage waveform and / or current waveform of the DC pulse, and the amount of change in each frequency component of the measured value of sensor S1. Based on this information, the determination unit 202 may determine whether further control is necessary to resolve the abnormality.

[0114] (Second Sequence Example) Figure 21 is a diagram illustrating a second sequence example of the control unit 2. In the following, explanations of operations common to the first sequence example may be omitted.

[0115] First, the acquisition unit 200 acquires measured values ​​related to the second voltage signal from the sensor S2 (St21). The measured values ​​related to the second voltage signal may include information regarding the amplitude of the first peak of the second voltage signal, and the amplitude and phase of the second peak.

[0116] Next, the determination unit 202 determines whether or not a given condition for detecting an anomaly is met based on the measurement value acquired by the acquisition unit 200 (St22). This condition may include, for example, a condition relating to the amplitude of the second peak of the second voltage signal, and a condition relating to the phase of the second peak.

[0117] If the determination unit 202 determines that the condition is met (i.e., if it determines that an abnormality exists), the decision unit 204 determines the variable element to be controlled and its control amount in order to resolve the abnormality (St23). Specifically, the decision unit 204 determines the variable element to be controlled and its control amount based on information such as the amplitude of the first peak of the second voltage signal, and the amplitude and phase of the second peak, and a control table. In one example, if the determination unit 202 determines that the amplitude of the second peak is below a predetermined threshold, the decision unit 204 determines the variable element to be controlled and its control amount by referring to the control table so that the amplitude of the second peak increases. In another example, if the determination unit 202 determines that the phase difference between the first peak and the second peak exceeds a predetermined threshold, the decision unit 204 determines the variable element to be controlled and its control amount by referring to the control table so that the phase of the second peak decreases. The instruction unit 206 instructs the second voltage generation unit 32b to determine the variable element and its control amount (St24). In one example, the determination unit 204 determines that the variable element to be controlled is an inductor 32bL1, which is a variable inductor, and the instruction unit 206 transmits an instruction to control the determined variable element.

[0118] The control unit 2 may repeatedly execute a series of control processes (St21 to St24). When the control unit 2 executes control for the second cycle or later, the acquisition unit 200 may further acquire the phase difference between the first peak and the second peak after the control instruction, the amount of phase change compared to before the control, the peak value, and the voltage offset value. Based on this information, the determination unit 202 may determine whether further control is necessary to resolve the abnormality.

[0119] (Third Sequence Example) Figure 22 is a diagram illustrating the third sequence example of the control unit 2. In the following, explanations of operations common to other sequence examples may be omitted.

[0120] First, the acquisition unit 200 acquires measured values ​​related to the state and / or generation of the plasma from the sensor S3 installed in the plasma processing chamber 10 (St31). The measured values ​​acquired from the sensor S3 can directly indicate information regarding the voltage waveform and / or current waveform on (or near) the wafer.

[0121] Next, the determination unit 202 determines whether or not a given condition for detecting an anomaly is met based on the measurement value acquired by the acquisition unit 200 (St32).

[0122] If the determination unit 202 determines that the condition is met (i.e., if it determines that an abnormality exists), the decision unit 204 refers to the control table and determines the variable element and its control amount that should be controlled in order to resolve the abnormality (St33). The instruction unit 206 instructs the second voltage generation unit 32b to determine the variable element and its control amount (St34).

[0123] The control unit 2 may repeatedly execute a series of control processes (St31 to St34). When the control unit 2 executes control for the second time or later, the acquisition unit 200 may further acquire information regarding the shape, offset amount, attenuation amount, phase change, frequency component change, etc., of the voltage waveform and / or current waveform on the wafer after the control instruction. Based on this information, the determination unit 202 may determine whether further control is necessary to resolve the abnormality.

[0124] (Example of the fourth sequence) Figure 23 is a diagram illustrating an example of the fourth sequence of the control unit 2. In the following, explanations of operations common to other sequence examples may be omitted.

[0125] First, the acquisition unit 200 acquires a measurement value related to the lower electrode BE from sensor S1 (St41). The acquisition unit 200 further acquires a measurement value related to the second voltage signal from sensor S2 (St42). The acquisition unit 200 further acquires a measurement value from sensor S3 installed in the plasma processing chamber 10 (St43). The acquisition unit 200 further acquires a measurement value related to the impedance matcher 31M from sensor S4 (St44).

[0126] Based on this information, the acquisition unit 200 can acquire (estimate) changes such as the amplitude and phase of the second voltage signal, the plasma density in the plasma processing chamber 10, the amount of phase change between the second voltage signal and the output of the lower electrode BE, the amount of offset of the voltage waveform and / or current waveform on the wafer, and the degree of neutralization.

[0127] Next, the determination unit 202 determines whether or not a given condition for detecting an anomaly is met based on the measurement values ​​acquired by the acquisition unit 200 and / or various information estimated based on those measurement values ​​(St45).

[0128] If the determination unit 202 determines that the condition is met (i.e., if it determines that an abnormality exists), the decision unit 204 refers to the control table and determines the variable element to be controlled and its control amount in order to resolve the abnormality (St46). The instruction unit 206 instructs the second voltage generation unit 32b to determine the variable element and its control amount (St47).

[0129] (Example of the fifth sequence) Figure 24 is a diagram illustrating an example of the fifth sequence of the control unit 2. The acquisition unit 200 further acquires a measurement value related to the second voltage signal from the sensor S2 (St 51). The acquisition unit 200 further acquires a measurement value related to the impedance matcher 31M from the sensor S4 (St 52).

[0130] Based on this information, the acquisition unit 200 acquires (estimates) information such as the amount of electrons, ions, and negative ions flowing into the plasma processing chamber 10, the acceleration voltage of electrons, ions, and negative ions to the upper electrode UE, and the amount of secondary electrons generated from the electrodes (upper electrode UE / lower electrode BE).

[0131] Next, the determination unit 202 determines whether or not an abnormal discharge or its precursor is occurring in the plasma processing chamber 10 based on the measurement values ​​acquired by the acquisition unit 200 and / or various information estimated based on those measurement values ​​(St 53).

[0132] If the determination unit 202 determines that an abnormal discharge or its precursor has occurred, the decision unit 204 refers to the control table and determines the variable element to be controlled and its control amount in order to resolve the abnormality (St 54). The instruction unit 206 instructs the second voltage generation unit 32b to use the determined variable element and its control amount (St 55).

[0133] The control unit 2 may repeatedly execute a series of control processes (St51 to St55). When the control unit 2 executes control for the second cycle or later, the acquisition unit 200 may further acquire information regarding the amount of electrons, ions, and negative ions flowing into the plasma processing chamber 10 or the upper electrode UE after the control instruction, the acceleration voltage of electrons, ions, and negative ions to the upper electrode UE, and the amount of secondary electrons generated from the electrodes (upper electrode UE / lower electrode BE). Based on this information, the determination unit 202 may determine whether further control is necessary to resolve the abnormality.

[0134] (Sixth Sequence Example) Figure 25 is a diagram illustrating the sixth sequence example of the control unit 2. In the following, explanations of operations common to other sequence examples may be omitted.

[0135] First, the acquisition unit 200 acquires a measurement value related to the lower electrode BE from sensor S1 (St61). The acquisition unit 200 further acquires a measurement value related to the second voltage signal from sensor S2 (St62). The acquisition unit 200 further acquires a measurement value from sensor S3 installed in the plasma processing chamber 10 (St63). The acquisition unit 200 further acquires a measurement value related to the impedance matcher 31M from sensor S4 (St64). The acquisition unit 200 further acquires a measurement value related to at least one of the plasma emission and electromagnetic waves in the plasma processing chamber 10 from sensor S5 (St65).

[0136] Based on this information, the acquisition unit 200 acquires (estimates) information such as the amount of electrons, ions, and negative ions flowing into the plasma processing chamber 10, the acceleration voltage of electrons, ions, and negative ions to the upper electrode UE, and the amount of secondary electrons generated from the electrodes (upper electrode UE / lower electrode BE).

[0137] Next, the determination unit 202 determines, based on the measurement values ​​acquired by the acquisition unit 200 and / or various information estimated based on those measurement values, whether or not light emission is occurring in the plasma processing chamber 10, whether or not the energy of electromagnetic waves in a specific frequency band in the plasma processing chamber 10 exceeds a predetermined threshold, whether or not an abnormal discharge or its precursor is occurring, etc. (St66).

[0138] If the determination unit 202 determines that an abnormality has occurred, the decision unit 204 refers to the control table and determines the variable element to be controlled and its control amount in order to resolve the abnormality (St 67). The instruction unit 206 instructs the second voltage generation unit 32b to determine the variable element and its control amount (St 68).

[0139] <Other configuration examples>

[0140] In the above embodiment, an example was described in which the voltage phase adjustment element 32bP is electrically connected between the rectifier element 32bD1 and the upper electrode UE, but it is not limited to this. The voltage phase adjustment element 32bP may be electrically connected between the ground potential and the rectifier element 32bD1. That is, the voltage phase adjustment element 32bP may be electrically connected in series with the rectifier element 32bD1 between the ground potential and the upper electrode UE.

[0141] A filter circuit may be electrically connected between the second voltage generation unit 32b and the upper electrode UE. The second voltage generation unit 32b and the filter circuit may be configured in the same housing or in separate housings. The filter circuit may be an HF filter circuit or a bias filter circuit. The HF filter circuit can filter signals in the frequency band of the source RF signal generated by the first RF generation unit 31a. That is, the HF filter circuit can block or attenuate signals in the frequency band of the source RF signal flowing from the upper electrode UE toward the second voltage generation unit 32b. The bias filter circuit can filter signals in the frequency band of the bias RF signal generated by the second RF generation unit 31b. That is, the bias filter circuit can block or attenuate signals in the frequency band of the bias RF signal flowing from the upper electrode UE toward the second voltage generation unit 32b.

[0142] The plasma processing apparatus 1 may include a plurality of second voltage generating units 32b. For example, if the plasma processing apparatus 1 includes a plurality of upper electrodes UE, one second voltage generating unit 32b may be electrically connected to each upper electrode UE. In this case, the plurality of second voltage generating units 32b may be composed of elements having different element constants.

[0143] In the above embodiment, an example was described in which the second voltage generation unit 32b is electrically connected to the upper electrode UE, but the embodiment is not limited to this. The second voltage generation unit 32b may be electrically connected to a conductive member. Figure 26 shows another example of coupling between the power supply system 30 and the plasma processing chamber 10. In the example shown in Figure 26, the second voltage generation unit 32b is electrically connected to the ring assembly 112 via the transmission line L6. That is, a second voltage signal may be supplied to the ring assembly 112. The remaining aspects may be the same as in the example shown in Figure 2.

[0144] As illustrated in Figure 26, the conductive member may be located within the plasma processing chamber 10, or may constitute a part of the plasma processing chamber 10, as long as it is not a ground electrode (including a conductive path to the ground electrode). For example, the conductive member may be a ring-shaped electrode located radially inward or outward of the ring assembly 112, in addition to the ring assembly 112 described above. Alternatively, the conductive member may be located on the inner wall of the plasma processing chamber 10, a liner arranged along the inner wall, or a baffle plate arranged to surround the substrate support portion 11. Furthermore, the conductive member may be located inside an upper electrode that is equipped with an insulator (in one example, at least a portion of which is covered with an insulator).

[0145] In the above embodiment, the rectifier element 32bD1 was described as a diode, but it is not limited to this. The rectifier element 32bD1 may be, for example, a vacuum tube or a microstructure vacuum device having a structure equivalent to that of a vacuum tube.

[0146] In the above embodiment, the rectifier current circuit 32b1 was described as comprising a high-frequency blocking element 32bL2 and a resistor 32bR2, but it is not limited to this. The rectifier current circuit 32b1 may consist of either the high-frequency blocking element 32bL2 or the resistor 32bR2.

[0147] In the above embodiment, an example was described in which the control unit 2 mainly controls the second voltage generation unit 32b, but it is not limited to this. The control unit 2 may control at least one of the first RF generation unit 31a and the second RF generation unit 31b based on a measurement value obtained from at least one of the sensors S1 to S5. In one example, if the control unit 2 determines that the plasma density in the plasma processing chamber 10 is below a predetermined threshold based on the measurement values ​​from the sensors S1 to S5, it controls the first RF generation unit 31a so that the plasma density increases.

[0148] In the above embodiment, with reference to Figures 18 to 25, an example was described in which the inductor 32bL1 of the voltage phase adjustment element 32bP is a variable element (i.e., the inductor 32bL1 is a variable inductor), but the embodiment is not limited to this. In one embodiment, the voltage phase adjustment element 32bP includes an inductor having a given inductance and a variable capacitor connected in series with the inductor, and the control unit 200 is configured to control the variable capacitor based on the output of one or more sensors (in one example, sensors S1 to S5) configured to monitor the state of the plasma in the plasma processing chamber 10.

[0149] In the above embodiment, with reference to Figures 18 to 25, the control unit 200 was described as being able to control the element constants of the high-frequency cut-off element 32bL2, but it is not limited to this. The high-frequency cut-off element 32bL2 may be determined in advance by the user of the plasma processing apparatus 1 (for example, at the time of determining the recipe) according to the frequency band to be attenuated, and the element constants may not be changed by the control unit 200.

[0150] This disclosure may include the following components:

[0151] [Note 1] A plasma processing apparatus comprising: a chamber; a substrate support portion disposed within the chamber and including a lower electrode; an upper electrode disposed above the substrate support portion; an RF signal generator electrically connected to the upper electrode or the lower electrode and configured to generate an RF signal for generating plasma in the chamber; a first voltage signal generator electrically connected to the lower electrode and configured to generate a first voltage signal having a sequence of first voltage pulses; a second voltage signal generator electrically connected to the upper electrode and configured to generate a second voltage signal, wherein the second voltage signal generator includes: a rectifier element electrically connected between the ground potential and the upper electrode; and a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the upper electrode; one or more sensors configured to monitor the state of plasma in the chamber; and a control unit configured to control the waveform of the second voltage signal based on the output of the one or more sensors.

[0152] [Note 2] The plasma processing apparatus according to Note 1, wherein the one or more sensors include a sensor configured to output a measurement value relating to the lower electrode.

[0153] [Note 3] The plasma processing apparatus according to Note 1 or 2, wherein the one or more sensors include a sensor configured to output a measurement value relating to the second voltage signal.

[0154] [Note 4] The plasma processing apparatus according to any one of Notes 1 to 3, wherein the one or more sensors include sensors installed in the chamber.

[0155] [Note 5] The plasma processing apparatus according to any one of Notes 1 to 4, wherein the one or more sensors include a sensor configured to output a measurement value relating to a matching circuit electrically connected to the RF signal generator.

[0156] [Note 6] The plasma processing apparatus according to any one of Notes 1 to 5, wherein the one or more sensors include a sensor configured to output a measurement value relating to at least one of the emission of plasma in the chamber and electromagnetic waves.

[0157] [Note 7] The plasma processing apparatus according to any one of Notes 1 to 6, wherein the voltage phase adjustment element includes a variable inductor, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

[0158] [Note 8] The plasma processing apparatus according to any one of Notes 1 to 8, wherein the voltage phase adjustment element includes a variable inductor and a capacitor connected in series, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

[0159] [Note 9] The plasma processing apparatus according to any one of Notes 1 to 8, wherein the control unit is configured to control the output of the RF signal generator based on the output of one or more sensors.

[0160] [Note 10] The plasma processing apparatus according to any one of Notes 1 to 9, wherein the second voltage signal generator further comprises a rectifier current circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element, the rectifier current circuit includes a variable resistor and a high-frequency cut-off element connected in series, and the control unit is configured to control the variable resistor based on the output of one or more sensors.

[0161] [Note 11] The plasma processing apparatus according to any one of Notes 1 to 10, wherein the second voltage signal generator further comprises an adjustment circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element, the adjustment circuit includes a variable capacitor, and the control unit is configured to control the variable capacitor based on the output of one or more sensors.

[0162] [Note 12] The plasma processing apparatus according to any one of Notes 1 to 11, wherein the second voltage signal generator further comprises an adjustment circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element, the adjustment circuit includes a variable inductor, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

[0163] [Note 13] The plasma processing apparatus according to any one of Notes 1 to 12, wherein the second voltage signal generator further includes: an offset voltage generator electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element and configured to offset the voltage generated at the upper electrode; a rectifier current circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element; and a capacitor electrically connected between the offset voltage generator and the rectifier current circuit, wherein the control unit is configured to control the output of the offset voltage generator based on the output of one or more sensors.

[0164] [Note 14] A plasma processing apparatus comprising: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber and including electrodes; a first voltage signal generator electrically connected to the electrodes and configured to generate a first voltage signal having a sequence of first voltage pulses; a conductive member constituting a part of the plasma processing chamber or disposed within the plasma processing chamber; a second voltage signal generator electrically connected to the conductive member and configured to generate a second voltage signal, wherein the second voltage signal generator includes: a rectifier element electrically connected between the ground potential and the conductive member; and a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the conductive member; one or more sensors configured to monitor the state of the plasma in the plasma processing chamber; and a control unit configured to control the waveform of the second voltage signal based on the output of the one or more sensors.

[0165] [Note 15] The plasma processing apparatus according to Note 14, wherein the one or more sensors include a sensor configured to output a measurement value relating to the electrode.

[0166] [Note 16] The plasma processing apparatus according to Note 14 or 15, wherein the one or more sensors include a sensor configured to output a measurement value relating to the second voltage signal.

[0167] [Note 17] The plasma processing apparatus according to any one of Notes 14 to 16, wherein the one or more sensors include sensors installed in the plasma processing chamber.

[0168] [Note 18] The plasma processing apparatus according to any one of Notes 14 to 7, wherein the one or more sensors include a sensor configured to output a measurement value relating to at least one of the emission of plasma in the plasma processing chamber and electromagnetic waves.

[0169] [Note 19] The plasma processing apparatus according to any one of Notes 14 to 18, wherein the voltage phase adjustment element includes an inductor and a variable capacitor connected in series, and the control unit is configured to control the variable capacitor based on the output of one or more sensors.

[0170] [Note 20] The plasma processing apparatus according to any one of Notes 14 to 19, wherein the control unit is configured to control the output of the RF signal generator based on the output of one or more sensors.

[0171] 1...Plasma processing apparatus, 2...Control unit, 10...Chamber, plasma processing chamber, 11...Substrate support unit, 13...Shower head, 30...Power supply system, 31a...First RF generation unit, 31b...Second RF generation unit, 32a...First voltage generation unit, 32b...Second voltage generation unit, 32bD1...Rectifier element, 32bP...Voltage phase adjustment element, 111...Main body, 1110...Base, UE...Upper electrode, BE...Lower electrode

Claims

1. A plasma processing apparatus comprising: a chamber; a substrate support portion disposed within the chamber and including a lower electrode; an upper electrode disposed above the substrate support portion; an RF signal generator electrically connected to the upper electrode or the lower electrode and configured to generate an RF signal for generating plasma in the chamber; a first voltage signal generator electrically connected to the lower electrode and configured to generate a first voltage signal having a sequence of first voltage pulses; a second voltage signal generator electrically connected to the upper electrode and configured to generate a second voltage signal, wherein the second voltage signal generator includes: a rectifier element electrically connected between the ground potential and the upper electrode; and a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the upper electrode; one or more sensors configured to monitor the state of plasma in the chamber; and a control unit configured to control the waveform of the second voltage signal based on the output of the one or more sensors.

2. The plasma processing apparatus according to claim 1, wherein the one or more sensors include a sensor configured to output a measurement value relating to the lower electrode.

3. The plasma processing apparatus according to claim 1, wherein the one or more sensors include a sensor configured to output a measurement value relating to the second voltage signal.

4. The plasma processing apparatus according to claim 1, wherein the one or more sensors include sensors installed in the chamber.

5. The plasma processing apparatus according to claim 1, wherein the one or more sensors include a sensor configured to output a measurement value relating to a matching circuit electrically connected to the RF signal generator.

6. The plasma apparatus according to claim 1, wherein the one or more sensors include a sensor configured to output a measurement value relating to at least one of the emission of plasma in the chamber and electromagnetic waves.

7. The plasma processing apparatus according to claim 1, wherein the voltage phase adjustment element includes a variable inductor, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

8. The plasma processing apparatus according to claim 1, wherein the voltage phase adjustment element includes a variable inductor and a capacitor connected in series, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

9. The plasma processing apparatus according to claim 1, wherein the control unit is configured to control the output of the RF signal generator based on the output of one or more sensors.

10. The plasma processing apparatus according to claim 1, wherein the second voltage signal generator further comprises a rectifier current circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element, the rectifier current circuit includes a variable resistor and a high-frequency cut-off element connected in series, and the control unit is configured to control the variable resistor based on the output of one or more sensors.

11. The plasma processing apparatus according to claim 1, wherein the second voltage signal generator further comprises an adjustment circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element, the adjustment circuit includes a variable capacitor, and the control unit is configured to control the variable capacitor based on the output of one or more sensors.

12. The plasma processing apparatus according to claim 1, wherein the second voltage signal generator further comprises an adjustment circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element, the adjustment circuit includes a variable inductor, and the control unit is configured to control the variable inductor based on the output of one or more sensors.

13. The plasma processing apparatus according to claim 1, wherein the second voltage signal generator further includes: an offset voltage generator electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element and configured to offset the voltage generated at the upper electrode; a rectifier current circuit electrically connected between the upper electrode and the ground potential and in parallel with the rectifier element; and a capacitor electrically connected between the offset voltage generator and the rectifier current circuit, wherein the control unit is configured to control the output of the offset voltage generator based on the output of one or more sensors.

14. A plasma processing apparatus comprising: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber and including electrodes; a first voltage signal generator electrically connected to the electrodes and configured to generate a first voltage signal having a sequence of first voltage pulses; a conductive member constituting a part of the plasma processing chamber or disposed within the plasma processing chamber; a second voltage signal generator electrically connected to the conductive member and configured to generate a second voltage signal, wherein the second voltage signal generator includes: a rectifier element electrically connected between the ground potential and the conductive member; and a voltage phase adjustment element electrically connected in series with the rectifier element between the ground potential and the conductive member; one or more sensors configured to monitor the state of the plasma in the plasma processing chamber; and a control unit configured to control the waveform of the second voltage signal based on the output of the one or more sensors.

15. The plasma processing apparatus according to claim 14, wherein the one or more sensors include a sensor configured to output a measurement value relating to the electrode.

16. The plasma processing apparatus according to claim 14, wherein the one or more sensors include a sensor configured to output a measurement value relating to the second voltage signal.

17. The plasma processing apparatus according to claim 14, wherein the one or more sensors include sensors installed in the plasma processing chamber.

18. The plasma processing apparatus according to claim 14, wherein the one or more sensors include a sensor configured to output a measurement value relating to at least one of the emission of plasma and electromagnetic waves in the plasma processing chamber.

19. The plasma processing apparatus according to claim 14, wherein the voltage phase adjustment element includes an inductor and a variable capacitor connected in series, and the control unit is configured to control the variable capacitor based on the output of one or more sensors.

20. The plasma processing apparatus according to claim 14, wherein the control unit is configured to control the output of the RF signal generator based on the output of one or more sensors.

Images