Plasma processing method and plasma processing device

Abstract

A plasma processing method according to the present disclosure is performed in a plasma processing device comprising a chamber, said plasma processing method comprising: (a) a step for using a voltage pulse generation unit to generate a bias DC signal that includes a sequence of voltage pulses; (b) a step for supplying the bias DC signal from the voltage pulse generation unit to a substrate support unit disposed inside the chamber via a path that electrically connects the substrate support unit and the voltage pulse generation unit; (c) a step for measuring the voltage of a voltage pulse; (d) a step for calculating at least one of the rise time and the fall time of the voltage pulse on the basis of the measured voltage of the voltage pulse; and (d) a step for adjusting at least one of the inductance of a variable inductor and the resistance value of a variable resistor electrically connected to the path, on the basis of at least one of the voltage of the voltage pulse and the rise time or the fall time of the voltage pulse.

Description

Plasma processing method and plasma processing apparatus

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is hereby incorporated by reference in its entirety into U.S. Patent Application No. 16 / 709,430, filed December 10, 2019 (U.S. Pat. No. 11,443,954), and U.S. Patent Application No. 63 / 612,152, filed December 19, 2023.

[0002] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to a plasma processing method and a plasma processing apparatus.

[0003] Patent Document 1 discloses a technique in which a negative DC voltage is periodically applied to a lower electrode from a DC power supply.

[0004] Japanese Patent Application Laid-Open No. 2019-36658

[0005] In one exemplary embodiment of the present disclosure, there is provided a plasma processing method for performing a plasma process on a substrate in a plasma processing apparatus including a chamber, the plasma processing being performed based on one or more parameters, the plasma processing method including the steps of: (a) generating a plasma from a process gas supplied to the chamber by a source RF signal; (b) generating a bias DC signal by a voltage pulse generator, the bias DC signal including a sequence of voltage pulses; (c) supplying the bias DC signal from the voltage pulse generator to a substrate support disposed in the chamber through a path electrically connecting the substrate support and the voltage pulse generator; and (d) adjusting at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path based on values ​​of the one or more parameters.

[0006] FIG. 1 is a diagram for explaining an example of the configuration of a plasma processing system. FIG. 2 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 3 is a circuit block diagram showing an example of the configuration of a power supply 30. FIG. 4 is a circuit block diagram showing an example of the configuration of a power supply 30. FIG. 5 is a flowchart showing an example of a plasma processing method according to an embodiment. FIG. 6 is a diagram showing an example of a waveform of a bias DC signal. FIG. 7 is a diagram showing an example of a waveform of a bias DC signal. FIG. 8 is a graph showing an example of a measurement result of the voltage of a bias DC signal. FIG. 9 is a diagram showing an example of a timing chart of plasma processing. FIG. 10 is a graph showing an example of a measurement result of the voltage of a bias DC signal. FIG. 11 is a graph showing an example of a measurement result of the voltage of a bias DC signal.

[0007] Hereinafter, each embodiment of the present disclosure will be described.

[0008] In one exemplary embodiment, a plasma processing method is provided for performing a plasma process on a substrate in a plasma processing apparatus including a chamber, the plasma process being performed based on one or more parameters, the plasma processing method including the steps of: (a) generating a plasma from a process gas supplied to the chamber by a source RF signal; (b) generating a bias DC signal by a voltage pulse generator, the bias DC signal including a sequence of voltage pulses; (c) supplying the bias DC signal from the voltage pulse generator to a substrate support disposed in the chamber through a path electrically connecting the voltage pulse generator to the substrate support; and (d) adjusting at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path based on values ​​of the one or more parameters.

[0009] In one exemplary embodiment, the plasma processing method further includes a step (e) of measuring values ​​of one or more parameters, and (d) includes adjusting at least one of the resistance value of the variable resistor and the inductance of the variable inductor based on the measured values ​​of the one or more parameters measured in (e).

[0010] In one exemplary embodiment, the one or more parameters include a voltage of the voltage pulse, and (e) includes: (e-1) measuring a voltage value of the voltage pulse as a value of the one or more parameters; and (e-2) calculating at least one of a rise time and a fall time of the voltage pulse based on the voltage value of the voltage pulse measured in (e-1), and in (d), at least one of the resistance value of the variable resistor and the inductance of the variable inductor is adjusted based on at least one of the rise time or fall time of the voltage pulse and the voltage value of the voltage pulse.

[0011] In one exemplary embodiment, in (e-1), the voltage of the voltage pulse is measured in the path between the variable resistor and the variable inductor and the substrate support.

[0012] In one exemplary embodiment, in (e-2), the rise time or fall time of the voltage pulse is the time it takes for the absolute value of the voltage of the voltage pulse to change from a first voltage value to a second voltage value that is higher than the first voltage value.

[0013] In one exemplary embodiment, (e-1) includes a step of calculating a maximum absolute value of the voltage of the voltage pulse, and in (e-2), the first voltage value is 10% or more of the maximum value, and the second voltage value is 90% or less of the maximum value.

[0014] In one exemplary embodiment, the variable resistor is connected in series in the path to the voltage pulse generator and the substrate support.

[0015] In one exemplary embodiment, the variable inductor is connected in series with the voltage pulse generator and the substrate support in the path.

[0016] In one exemplary embodiment, the plasma processing method further includes a step (f) of setting values ​​of one or more parameters, and (d) includes adjusting at least one of the resistance value of the variable resistor and the inductance of the variable inductor based on the set values ​​of the one or more parameters set in (f).

[0017] In one exemplary embodiment, (f) includes: (f-1) setting a value of at least one of the one or more parameters to a first value; and (f-2) setting a value of at least one of the at least one parameter to a second value different from the first value; (d) includes: (d-1) adjusting at least one of a resistance value of the variable resistor and an inductance of the variable inductor based on the first value; and (d-2) adjusting at least one of a resistance value of the variable resistor and an inductance of the variable inductor based on the second value; and the one or more parameters include at least one selected from the group consisting of a pressure in the chamber, an elapsed time of the plasma processing, a frequency of the source RF signal, a power of the source RF signal, and a flow rate of the process gas.

[0018] In one exemplary embodiment, (f) includes the one or more parameters including a frequency of the source RF signal, and (a) includes generating plasma with a source RF signal having a first frequency based on a first value set in (a-1)(f-1), and generating plasma with a source RF signal having a second frequency lower than the first frequency based on a second value set in (a-2)(f-2).

[0019] In one exemplary embodiment, while (a-1) is being performed, in (d-1), the resistance value of the variable resistor is adjusted to a first resistance value, and while (a-2) is being performed, in (d-2), the resistance value of the variable resistor is adjusted to a second resistance value higher than the first resistance value.

[0020] In one exemplary embodiment, the voltage pulse of the bias DC signal includes multiple inflection points, and the maximum voltage difference between the multiple inflection points while (a-1) is being performed is greater than the maximum voltage difference between the multiple inflection points while (a-2) is being performed.

[0021] In one exemplary embodiment, activated species contained in the plasma generated while (a-1) and (a-2) are being performed are directed toward the substrate by (c), and the directionality of the activated species toward the substrate while (a-1) is being performed is lower than the directionality of the activated species toward the substrate while (a-2) is being performed.

[0022] In one exemplary embodiment, while (a-1) is being performed, products generated from the processing gas are deposited on the substrate, and while (a-2) is being performed, at least a portion of the products are removed by plasma generated from the processing gas.

[0023] In one exemplary embodiment, the resistance is between 5 ohms and 500 ohms.

[0024] In one exemplary embodiment, the inductance is between 1 μH and 50 μH.

[0025] In one exemplary embodiment, a plasma processing apparatus is provided, comprising a chamber and a controller, for performing a plasma processing on a substrate based on one or more parameters, wherein the controller is configured to: (a) control a source RF signal to generate a plasma from a process gas supplied to the chamber, (b) control a voltage pulse generator to generate a bias DC signal, the bias DC signal including a sequence of voltage pulses, (c) control the voltage pulse generator to supply the bias DC signal to a substrate support disposed in the chamber via a path electrically connecting the voltage pulse generator to the substrate support, and (d) control at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path, based on values ​​of the one or more parameters.

[0026] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, 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 the actual ratios are not limited to the ratios shown in the drawings.

[0027] FIG. 1 is a diagram illustrating an exemplary 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 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 exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0028] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0029] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform 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 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0030] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0031] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms 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 showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0032] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a 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 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0033] 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 disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be described later, is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0034] 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 cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0035] The substrate support 11 may also include a temperature adjustment 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 adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0036] The showerhead 13 is configured to introduce at least one process 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 multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0037] 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 process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0038] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0039] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple 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.

[0040] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0041] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0042] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0043] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided 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 in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0044] 3 is a circuit block diagram showing an example of the configuration of the power supply 30. The power supply 30 can be configured to include a voltage pulse generating unit 33, a path 60, a variable resistor 70, a variable inductor 80, and a variable capacitor 90.

[0045] Path 60 is a path for electrically connecting the output of voltage pulse generator 33 and substrate support 11. Furthermore, variable resistor 70 is disposed on path 60 so as to be connected in series to voltage pulse generator 33 and substrate support 11. That is, the sequence of voltage pulses generated in voltage pulse generator 33 is supplied to substrate support 11 via path 60 and variable resistor 70.

[0046] The variable resistor 70 is a resistor whose resistance value is adjustable. The variable resistor 70 is connected in series with the voltage pulse generating unit 33 and the substrate support unit 11 on the path 60. In one embodiment, the variable resistor 70 adjusts its resistance value based on an instruction from the control unit 2. The resistance added to the path 60 changes based on the resistance value of the variable resistor 70. The voltage of the voltage pulse output from the voltage pulse generating unit 33 to the path 60 can be reduced based on the resistance value of the variable resistor 70. In other words, the variable resistor 70 can correct the maximum value of the voltage pulse. This can correct the pulse shape of the voltage pulse.

[0047] The variable inductor 80 is an inductor whose inductance is adjustable. The variable inductor 80 is connected in series with the voltage pulse generating unit 33 and the substrate support 11 on the path 60. The variable resistor 70 and the variable inductor 80 may be arranged at any position on the path 60. In one embodiment, the variable inductor 80 adjusts its inductance based on an instruction from the control unit 2. The inductance added to the path 60 changes based on the inductance of the variable inductor 80. The rise time and fall time of the voltage pulse output from the voltage pulse generating unit 33 to the path 60 can be lengthened based on the inductance of the variable inductor 80. In other words, the rise time and fall time of the voltage pulse can be corrected by the variable inductor 80. This allows the pulse shape of the voltage pulse to be corrected.

[0048] The variable capacitor 90 is a capacitor whose capacitance is adjustable. The variable capacitor 90 is connected to the path 60 so as to add capacitance to the path 60. In one embodiment, the variable capacitor 90 adjusts the capacitance of the variable capacitor 90 based on an instruction from the control unit 2. The resistance added to the path 60 changes based on the capacitance of the variable capacitor 90. The voltage of the voltage pulse output from the voltage pulse generating unit 33 to the path 60 can change based on the capacitance of the variable capacitor 90. As an example, the variable capacitor 90 can change the rise time and / or fall time of the voltage of the voltage pulse. This can correct the pulse shape of the voltage pulse.

[0049] In one embodiment, the control unit 2 is electrically connected to the voltage pulse generating unit 33, the path 60, the variable resistor 70, and the variable inductor 80. The control unit 2 can measure the voltage of the voltage pulse propagating through the path 60. The control unit 2 can measure the voltage of the voltage pulse between the variable resistor 70 and the variable inductor 80 and the substrate support 11 on the path 60. The control unit 2 can control the voltage pulse generating unit 33, the variable resistor 70, and / or the variable inductor 80 based on the measured voltage of the voltage pulse.

[0050] The first RF generating unit 31a (see FIG. 2) may be electrically connected to the substrate support 11 via a path 60. The first RF generating unit 31a may be electrically connected to the path 60 between the variable resistor 70 and the variable inductor 80 and the substrate support 11. The first RF generating unit 31a may also be electrically connected to the substrate support 11 via a path different from the path 60.

[0051] (Another Example of the Configuration of the Power Supply 30) Fig. 4 is a circuit block diagram showing another example of the configuration of the power supply 30. The variable resistor 70 may be configured to include a plurality of fixed resistors 71 and a plurality of switches 72. Fig. 4 shows an example including three fixed resistors 71-1 to 71-3 and three switches 72-1 to 72-3. Furthermore, the variable inductor 80 may be configured to include a plurality of fixed inductors 81 and a plurality of switches 82. Fig. 4 shows an example including three fixed inductors 81-1 to 81-3 and three switches 82-2. The switches 72-1 to 72-3 and the switches 82-1 to 82-3 may be configured to include FETs or PIN diodes.

[0052] In the example of the variable resistor 70 shown in FIG. 4, the fixed resistors 71-1 to 71-3 are connected in parallel to one another. Each of the fixed resistors 71-1 to 71-3 has a first end and an other end. The switches 72-1 to 72-3 are arranged in parallel to one another. Each of the switches 72-1 to 72-3 has a first end and an other end. One end of the switches 72-1 to 72-3 is electrically connected to the voltage pulse generating unit 33. The other end of the switches 72-1 to 72-3 is connected to one end of the corresponding fixed resistors 71-1 to 71-3. The other end of the fixed resistors 71-1 to 71-3 is electrically connected to the variable inductor 80.

[0053] That is, in the variable resistor 70, the switches 72-1 to 72-3 are connected in series to the fixed resistors 71-1 to 71-3. The control unit 2 can adjust the resistance value of the variable resistor 70 by controlling the on / off of each of the switches 72-1 to 72-3. That is, the resistance value of the variable resistor 70 can be adjusted according to the resistance value of the fixed resistor 71 whose corresponding switch 72 is on. Note that the variable resistor 70 may be configured so that multiple fixed resistors 71 are connected in series. In this case, each of the multiple switches 72 may be connected in parallel to the corresponding fixed resistor 71.

[0054] In the example of the variable inductor 80 shown in FIG. 4, the fixed inductors 81-1 to 81-3 are connected in parallel to one another. Each of the fixed inductors 81-1 to 81-3 has one end and the other end. The switches 82-1 to 82-3 are arranged in parallel to one another. Each of the switches 82-1 to 82-3 has one end and the other end. One end of the switches 82-1 to 82-3 is electrically connected to the variable resistor 70. The other end of the switches 82-1 to 82-3 is connected to one end of the corresponding fixed inductor 81-1 to 81-3. The other end of the fixed inductors 81-1 to 81-3 is electrically connected to the substrate support 11.

[0055] That is, in the variable inductor 80, the switches 82-1 to 82-3 are connected in series to the fixed inductors 81-1 to 81-3. The control unit 2 can adjust the inductance of the variable inductor 80 by controlling the on / off of each of the switches 82-1 to 82-3. That is, the inductance of the variable inductor 80 can be adjusted according to the inductance of the fixed inductor 81 whose corresponding switch 82 is on. Note that the variable inductor 80 may be configured such that multiple fixed inductors 81 are connected in series. In this case, each of the multiple switches 82 may be connected in parallel to the corresponding fixed inductor 81.

[0056] In the example of the variable capacitor 90 shown in FIG. 4, the fixed capacitors 91-1 to 91-3 are connected in parallel to one another. Each of the fixed capacitors 91-1 to 91-3 has a first end and an other end. The switches 82-1 to 82-3 are arranged in parallel to one another. Each of the switches 82-1 to 82-3 has a first end and an other end. One end of the switches 82-1 to 82-3 is electrically connected to the path 60. The other end of the switches 82-1 to 82-3 is connected to one end of the corresponding fixed capacitor 91-1 to 91-3. The other end of the fixed capacitors 91-1 to 91-3 is grounded.

[0057] That is, in the variable capacitor 90, the switches 82-1 to 82-3 are connected in series to the fixed capacitors 91-1 to 91-3. The control unit 2 can adjust the capacitance of the variable capacitor 90 by controlling the on / off of each of the switches 82-1 to 82-3. That is, the capacitance of the variable capacitor 90 can be adjusted according to the capacitance of the fixed capacitor 91 whose corresponding switch 82 is on. Note that the variable capacitor 90 may be configured so that a plurality of fixed capacitors 91 are connected in series. In this case, each of the plurality of switches 82 may be connected in parallel to the corresponding fixed capacitor 91.

[0058] (Example of the Present Processing Method) Figure 5 is a flowchart showing an example of a plasma processing method according to one embodiment. (Hereinafter, this plasma processing method will also be referred to as the "present processing method.") The present processing method includes a step of setting plasma processing parameters (ST0), a step of preparing a substrate (ST1), a step of supplying a processing gas (ST2), a step of supplying a source RF signal (ST3), a step of supplying a bias DC signal (ST4), a step of measuring the voltage of the bias DC signal (ST5), a step of measuring the rise time and / or fall time of a voltage pulse (ST6), and a step of adjusting the resistance value of a variable resistor and / or the inductance of a variable inductor (ST7). Below, an example of the present processing method will be described using a method for etching a substrate as an example.

[0059] (Step ST0: Setting Plasma Processing Parameters) In step ST0, one or more parameters for performing plasma processing on a substrate are set. Steps ST2 to ST7, which will be described later, can each be performed based on one or more parameters set in step ST0. Each of steps ST0 to ST7 can be performed by the control unit 2 controlling the configuration included in the plasma processing apparatus 1. As an example, the control unit 2 can be configured to include the configuration shown in FIG. 9 of U.S. Patent Application No. 16 / 709,430 (U.S. Patent No. 11,443,954), which is incorporated herein by reference.

[0060] In one embodiment, setting one or more parameters may include the controller 2 storing one or more parameters in the memory unit 2a2. Also, setting one or more parameters may include the controller 2 selecting one or more parameters from a plurality of parameters stored in the memory unit 2a2. Also, setting one or more parameters may include the user of the plasma processing apparatus 1 inputting one or more parameters into the plasma processing apparatus 1 via an input device.

[0061] The one or more parameters may be parameters included in a process recipe for performing the plasma processing, and in one embodiment, setting the one or more parameters may be storing, selecting, or entering a process recipe.

[0062] The one or more parameters may be parameters for performing plasma processing on the substrate W. As an example, the parameters may include the frequency of the source RF signal, the power of the source RF signal, the frequency of the bias RF signal, the power of the bias RF signal, the type of reactive gas contained in the processing gas, the flow rate of the processing gas, the flow rate of each reactive gas contained in the processing gas, the pressure in the chamber, and / or the time of the plasma processing.

[0063] The one or more parameters may also include a frequency of the bias DC signal, a duty ratio in one cycle of the bias DC signal, a frequency of the sequence of voltage pulses, a voltage of the voltage pulses, a rise time of the voltage pulses, a fall time of the voltage pulses, and / or a voltage difference between inflection points included in the voltage pulses.

[0064] Additionally, if the plasma treatment is performed over multiple periods, the one or more parameters may include the number of periods included in the plasma treatment, the order of each period, and / or the duration of the plasma treatment in each period.

[0065] (Process ST1: Preparation of Substrate) In process ST1, a substrate W is prepared. In one embodiment, the substrate W may include an etching target film that is to be etched and a mask film on the etching target film. In process ST1, the substrate W may be placed on a substrate support surface on the substrate support 11.

[0066] (Step ST2: Supply of Processing Gas) In step ST2, a processing gas is supplied into the plasma processing chamber 10. The processing gas includes an etching gas that etches a film to be etched included in the substrate W. The type and number of etching gases included in the processing gas can be selected as appropriate.

[0067] (Step ST3: Supply of Source RF Signal) In step ST3, a source RF signal is supplied to the substrate support 11 or the shower head 13. The frequency and power of the source RF signal can be selected appropriately. The source RF signal may be a continuous wave or a pulse wave.

[0068] (Process ST4: Supply of Bias DC Signal) In process ST4, a bias DC signal is supplied to the substrate support part 11. In one embodiment, the bias DC signal is a signal including a sequence of voltage pulses. FIG. 6 is a diagram showing an example of a waveform of the bias DC signal. The bias DC signal may be a signal that repeats a period T. That is, the period T is one cycle of the bias DC signal. In one embodiment, the period T includes a period Ta and a period Tb. The period Ta may be a period that includes a sequence of voltage pulses. The period Tb is a period that does not include a sequence of voltage pulses. The ratio between the period Ta and the period Tb, i.e., the duty ratio, may be set appropriately. Note that the bias DC signal may be a continuous wave that includes successive voltage pulses during the period in which the voltage pulses are supplied to the substrate support part 11, as shown in FIG. 7.

[0069] The voltage of the voltage pulse can be set appropriately depending on the target value of the substrate potential. In the bias DC signal, each voltage pulse can be a positive pulse or a negative pulse. In the examples shown in FIGS. 6 and 7, each voltage pulse is a negative pulse. That is, the voltage pulse sequence can repeat a voltage V1 and a voltage V2 that is lower than voltage V1. In addition, during period Tb, the voltage of the bias DC signal can be voltage V1. Here, voltage V1 can be the minimum voltage setting value of the voltage pulse. In addition, voltage V2 can be the maximum voltage setting value of the voltage pulse. As an example, voltage V1 is zero voltage. As another example, voltage V2 is a negative voltage of -1 kV to -10 kV.

[0070] (Process ST5: Measurement of Voltage of Bias DC Signal) In process ST5, the control unit 2 measures the voltage of the bias DC signal. As the voltage of the bias DC signal, the voltage of the sequence of voltage pulses during the period Ta may be measured. The voltage of the bias DC signal may be measured on the path 60 between the variable resistor 70 and the variable inductor 80 and the substrate support 11. The voltage of the bias DC signal may be measured on the path 60 near the substrate support 11. FIG. 8 is a graph showing an example of the measurement result of the voltage of the bias DC signal. FIG. 8 shows a portion of the measurement result of the voltage of the bias DC signal corresponding to the two voltage pulses in FIGS. 6 and 7. In process ST5, as shown in FIG. 8, the voltage of the bias DC signal may be measured to obtain a voltage waveform of the bias DC signal. Furthermore, in process ST5, the maximum value of the measured voltage of the voltage pulse may be calculated. As an example, the maximum value is the voltage Vmax in FIG. 8. The voltage Vmax may be one of the peak values ​​of the measured voltage pulses. The maximum value may be the maximum absolute value of the measurement values.

[0071] (Step ST6: Calculation of Rise Time and / or Fall Time) In step ST6, the control unit 2 calculates the rise time and / or fall time of the voltage pulse. In one embodiment, the rise time and / or fall time of the voltage pulse may be the time required for the voltage of the bias DC signal measured in step ST5 to reach the second voltage from the first voltage. As an example, the first voltage is the voltage Vs1 and / or Vs2 in FIG. 8. The voltages Vs1 and Vs2 may be calculated using the following equations (1-1) and (1-2), respectively. Vs1=Vmax-Vmin×α1 (1-1) Vs2=Vmax-Vmin×α2 (1-2) Here, as an example, α1 and α2 are 5% to 30%. Furthermore, α1 and α2 may be 10%, 20%, or 30%. Note that α1 and α2 may be different values. Furthermore, the voltages Vs1 and / or Vs2 may be calculated based on the voltage V1 instead of the voltage Vmin.

[0072] As an example, the second voltage is the voltage Vt1 and / or Vt2 in FIG. 8. The absolute values ​​of the voltages Vt1 and Vt2 may be set to be higher than the absolute values ​​of the voltages Vs1 and Vs2, respectively. The voltages Vt1 and Vt2 may be calculated using the following equations (2-1) and (2-2), respectively: Vt1=Vmax-Vmin×β1 (2-1) Vt2=Vmax-Vmin×β2 (2-2) Here, as an example, β1 and β2 are 70% to 95%. β1 and β2 may be 70%, 80%, or 90%. β1 and β2 may be different values. The voltages Vt1 and Vt2 may be calculated based on the voltage V2 instead of the voltage Vmax.

[0073] The control unit 2 can calculate the rise time and / or fall time based on the first voltage and the second voltage. In the example shown in Fig. 8 , the fall time t1 of the voltage pulse is the time required for the voltage of the voltage pulse to reach voltage Vt1 from voltage Vs1. The rise time t2 of the voltage pulse is the time required for the voltage of the voltage pulse to reach voltage Vs2 from voltage Vt2. As an example, the control unit 2 may calculate the fall time t1 and / or t2 using voltage Vmin in Fig. 8 as the first voltage and voltage Vmax in Fig. 8 as the second voltage.

[0074] In step ST6, the control unit 2 may calculate the flatness of the waveform of the voltage pulse. The flatness of the waveform of the voltage pulse may be the flatness during a time interval t3. The time interval t3 may be the time interval between the falling time t1 and the rising time t2. The flatness of the waveform of the voltage pulse may be calculated based on the distribution of the voltage values ​​of the voltage pulse. Furthermore, the flatness of the waveform of the voltage pulse may be calculated based on the voltage values ​​of the inflection points included in the waveform of the voltage pulse. As an example, the inflection points may be inflection points P1, P2, and / or P3 in FIG. 8.

[0075] (Step ST7: Adjustment of Variable Resistor and / or Variable Inductor) In step ST7, the control unit 2 adjusts the variable resistor 70 and / or the variable inductor 80. In one embodiment, the control unit 2 adjusts the variable resistor 70 and / or the variable inductor 80 so that the waveform of the voltage pulse measured in step ST5 approaches a predetermined shape. The shape may be any shape depending on the purpose of the plasma processing. In one embodiment, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the waveform of the voltage pulse approaches a rectangular or trapezoidal shape. Alternatively, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the waveform of the voltage pulse deviates from a rectangular or trapezoidal shape. Alternatively, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 based on the set values ​​and / or measured values ​​of other parameters of the plasma processing.

[0076] In one embodiment, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 to adjust the linearity of the activated species traveling from the plasma toward the substrate W. As an example, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the waveform of the voltage pulse approaches a rectangular or trapezoidal shape, thereby increasing the linearity of the activated species traveling from the plasma toward the substrate W. Alternatively, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the waveform of the voltage pulse deviates from a rectangular or trapezoidal shape, thereby decreasing the linearity of the activated species traveling from the plasma toward the substrate W.

[0077] For example, factors that define the proximity of the waveform of the voltage pulse to the shape may include the height of the voltage pulse, the shape of the rising waveform of the voltage pulse, the angle of the rising waveform of the voltage pulse, the shape of the falling waveform of the voltage pulse, the angle of the falling waveform of the voltage pulse, and / or the voltage difference between inflection points included in the waveform of the voltage pulse. The control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 directly or indirectly based on at least one of these factors.

[0078] In one embodiment, the control unit 2 adjusts the resistance value of the variable resistor 70 based on the voltage Vmax measured or calculated in step ST5. The control unit 2 may adjust the resistance value of the variable resistor 70 by comparing the voltage Vmax with a predetermined voltage. The predetermined voltage may be the voltage V2. As an example, when the absolute value of the voltage Vmax is higher than the voltage V2, the control unit 2 adjusts the variable resistor 70 to increase the resistance value of the variable resistor 70. On the other hand, when the absolute value of the voltage Vmax is lower than the voltage V2, the control unit 2 adjusts the variable resistor 70 to decrease the resistance value of the variable resistor 70. As a result, the voltage Vmax of the voltage pulse output from the voltage pulse generating unit 33 to the path 60 can be corrected based on the resistance value of the variable resistor 70. Note that the control unit 2 may control the voltage pulse generating unit 33 to correct the voltage Vmax of the voltage pulse output by the voltage pulse generating unit 33.

[0079] In one embodiment, the control unit 2 adjusts the inductance of the variable inductor 80 based on the rise time and / or fall time calculated in step ST6. The control unit 2 may adjust the inductance of the variable inductor 80 by comparing the rise time and / or fall time calculated in step ST6 with a predetermined rise time and / or fall time. As an example, if the fall time t calculated in step ST6 is longer than the predetermined fall time, the control unit 2 adjusts the variable inductor 80 to reduce the inductance of the variable inductor 80. On the other hand, if the fall time t is shorter than the predetermined fall time, the control unit 2 adjusts the variable inductor 80 to increase the inductance of the variable inductor 80. In this way, the rise time and / or fall time of the voltage pulse output from the voltage pulse generating unit 33 to the path 60 can be corrected based on the inductance of the variable inductor 80.

[0080] After the resistance value of the variable resistor 70 and / or the inductance of the variable inductor 80 are adjusted in step ST7, the control unit 2 may continue to supply the source RF signal and the bias DC signal to continue plasma processing on the substrate W.

[0081] (Another Example of the Present Processing Method) The present processing method may be performed by repeatedly executing a cycle including two or more periods. In this case, some or all of steps ST2 to ST7 may be performed in parallel in each period. The control unit 2 may adjust the resistance value of the variable resistor 70 and / or the inductance of the variable inductor 80 so that the voltage pulse has a different waveform in each period. With reference to FIG. 9 , an example in which the present processing method is performed by repeatedly executing a cycle including two periods will be described.

[0082] FIG. 9 is a diagram showing an example of a timing chart of plasma processing according to an exemplary embodiment. In FIG. 9, the horizontal axis represents time, and the vertical axis represents the flow rate of the reactive gas contained in the process gas, the power of the source RF signal, and the voltage of the bias DC signal. The power of the source RF signal is the effective value of the power. The voltage of the bias DC signal is the absolute value of the voltage. In FIG. 9, the vertical axis indicates a larger value as it moves upward. Note that the flow rates S1 and S2 in FIG. 9 do not necessarily represent an absolute relationship between the flow rates. Also, the powers P1 and P2 in FIG. 9 do not necessarily represent an absolute relationship between the powers. Also, the voltages V1 and V2 in FIG. 9 do not necessarily represent an absolute relationship between the voltages.

[0083] In the example shown in FIG. 9 , one cycle of the present processing method includes Period 1 and Period 2. In each period, the parameters of the plasma processing can be set arbitrarily. In one embodiment, in each period, a reaction in which deposits are generated on the substrate W (hereinafter also referred to as a "deposition reaction") and a reaction in which the deposits are etched (hereinafter also referred to as an "etching reaction") can occur in parallel by the plasma generated from the processing gas. When the deposition reaction exceeds the etching reaction, deposition of products on the substrate W can proceed. On the other hand, when the etching reaction exceeds the deposition reaction, etching of products on the substrate W can proceed. Hereinafter, a state in which the deposition reaction exceeds the etching reaction is also referred to as "the deposition reaction is dominant." Furthermore, a state in which the etching reaction exceeds the deposition reaction is also referred to as "the etching reaction is dominant."

[0084] In the example shown in FIG. 9 , a plasma process in which a deposition reaction is dominant is performed in period 1. A plasma process in which an etching reaction is dominant is performed in period 2. Specifically, as an example, the flow rate of the reaction gas may be set to a flow rate S1 in period 1, and set to a flow rate S2 lower than the flow rate S1 in period 2. The flow rate S2 may be zero. As an example, the effective value of the power of the source RF signal may be set to a power P2 in period 1, and set to a power P1 lower than the power P2 in period 2. As an example, the absolute value of the maximum pulse voltage of the bias DC signal may be set to a voltage V1 in period 1, and set to a voltage V2 higher than the voltage V1 in period 2. The voltage V1 may be zero. The voltage V2 may be a negative voltage.

[0085] The waveform of the voltage pulse of the bias DC signal may have a different shape in Period 1 and Period 2. In one embodiment, the control unit 2 may adjust the waveform of the voltage pulse in each period by adjusting the variable resistor 70 and / or the variable inductor 80. As an example, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 depending on the balance between the deposition reaction and the etching reaction in each period.

[0086] 9 , since the deposition reaction is dominant in period 1, the control unit 2 can adjust the variable resistor 70 and / or the variable inductor 80 to decrease the directivity of the activated species moving from the plasma toward the substrate W. On the other hand, since the etching reaction is dominant in period 2, the control unit 2 can adjust the variable resistor 70 and / or the variable inductor 80 to increase the directivity of the activated species moving from the plasma toward the substrate W.

[0087] 10 and 11 are graphs showing an example of measurement results of the voltage of a bias DC signal. FIG. 10 shows the measurement results of the voltage of the bias DC signal during period 1. FIG. 11 shows the measurement results of the voltage of the bias DC signal during period 2. In FIGS. 10 and 11, the voltage pulse of the bias DC signal has negative polarity. The waveform of the voltage pulse includes inflection points P1, P2, and P3. Inflection points P1 and P2 are inflection points where the rate of change of the voltage of the bias DC signal changes from negative to positive. Inflection point P3 is inflection point where the rate of change of the voltage of the bias DC signal changes from positive to negative. Inflection point P1 may be the inflection point immediately after the falling edge of the waveform of the voltage pulse. Inflection point P2 may be the inflection point immediately before the rising edge of the waveform of the voltage pulse.

[0088] As shown in FIG. 10 , the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the voltage difference Vpp between the voltage value Vmax at the inflection point P1 and the voltage value Vmid at the inflection point P2 is equal to or greater than a predetermined value. For example, during period 1, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the voltage difference Vpp is equal to or greater than a predetermined value. This may reduce the linearity of the activated species traveling from the plasma toward the substrate W. Note that, for example, in the example shown in FIG. 10 , the resistance value of the variable resistor 70 is set to 33 Ω, and the inductance of the variable inductor 80 is set to 7.5 μH. The voltage difference Vpp may also be the potential difference between the inflection point P1 and the inflection point P3.

[0089] On the other hand, as shown in FIG. 11 , the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the potential difference Vpp is equal to or less than a predetermined value. For example, during period 2, the control unit 2 may adjust the variable resistor 70 and / or the variable inductor 80 so that the voltage difference Vpp is equal to or less than a predetermined value. This may increase the directivity of the activated species traveling from the plasma toward the substrate W. The control unit 2 may also adjust the variable resistor 70 and / or the variable inductor 80 so that the voltage difference Vpp approaches zero. For example, in the example shown in FIG. 11 , the resistance value of the variable resistor 70 is set to 80 Ω, and the inductance of the variable inductor 80 is set to 12.5 μH. The voltage difference Vpp may be the potential difference between the inflection point P1 and the inflection point P3.

[0090] According to an embodiment of the present disclosure, the shape of a voltage pulse included in a bias DC signal can be corrected based on plasma processing parameters. As an example, the correction can be performed during plasma processing. This allows correction of the effect of the plasma processing parameter setting on the waveform of the voltage pulse. Furthermore, even if the plasma processing parameter setting is changed during plasma processing, the effect of the change on the waveform of the voltage pulse can be corrected. This allows suppressing the effect of the plasma processing parameter setting and its change on the potential of the substrate W and, ultimately, the etching characteristics.

[0091] Furthermore, according to an embodiment of the present disclosure, it is possible to correct the influence of changes over time on the waveform of the voltage pulse. For example, even if the shape of the voltage pulse supplied to the substrate support 11 changes over time due to repeated etching processes in the plasma processing apparatus 1, the change in the voltage pulse over time can be corrected. This makes it possible to suppress changes over time in the potential of the substrate W, thereby suppressing changes over time in the etching characteristics caused by changes over time in the voltage pulse.

[0092] Furthermore, according to an embodiment of the present disclosure, a change in the waveform of a voltage pulse generated during plasma processing can be corrected during the plasma processing, thereby suppressing a change in the potential of the substrate W that occurs during plasma processing, and thereby suppressing a change in etching characteristics caused by a change in the voltage pulse that occurs during plasma processing.

[0093] Furthermore, according to an embodiment of the present disclosure, the waveform of the voltage pulse can be corrected at any timing during plasma processing. For example, when a cycle including two or more periods is repeatedly executed during plasma processing, the waveform of the voltage pulse can be corrected for each period. This allows the waveform of the voltage pulse to be corrected according to the purpose of the plasma processing in each period.

[0094] According to one exemplary embodiment of the present disclosure, a technique can be provided that can correct voltage pulses in a bias DC signal.

[0095] The present disclosure may include, for example, the following configurations.

[0096] (Supplementary Note 1) A plasma processing method for performing plasma processing on a substrate in a plasma processing apparatus having a chamber, the plasma processing being performed based on one or more parameters, the plasma processing method comprising: (a) generating plasma from a processing gas supplied to the chamber by a source RF signal; (b) generating a bias DC signal by a voltage pulse generating unit, the bias DC signal including a sequence of voltage pulses; (c) supplying the bias DC signal from the voltage pulse generating unit to a substrate support disposed in the chamber via a path electrically connecting the voltage pulse generating unit to the substrate support; and (d) adjusting at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path based on values ​​of the one or more parameters.

[0097] (Supplementary Note 2) The plasma processing method according to Supplementary Note 1, further comprising the step of (e) measuring the values ​​of the one or more parameters, wherein (d) comprises adjusting at least one of the resistance value of the variable resistor and the inductance of the variable inductor based on the measured values ​​of the one or more parameters measured in (e).

[0098] (Supplementary Note 3) The one or more parameters include a voltage of the voltage pulse, and (e) comprises: (e-1) a step of measuring a voltage value of the voltage pulse as a value of the one or more parameters; and (e-2) a step of calculating at least one of a rise time and a fall time of the voltage pulse based on the voltage value of the voltage pulse measured in (e-1), and in (d), at least one of a resistance value of the variable resistor and an inductance of the variable inductor is adjusted based on at least one of the rise time or fall time of the voltage pulse and the voltage value of the voltage pulse.

[0099] (Supplementary Note 4) The plasma processing method according to Supplementary Note 3, wherein in (e-1), the voltage of the voltage pulse is measured in the path between the variable resistor and the variable inductor and the substrate support.

[0100] (Supplementary Note 5) The plasma processing method according to Supplementary Note 3 or 4, wherein in (e-2), the rise time or fall time of the voltage pulse is a time required for the absolute value of the voltage of the voltage pulse to change from a first voltage value to a second voltage value higher than the first voltage value.

[0101] (Supplementary Note 6) The plasma processing method according to Supplementary Note 5, wherein (e-1) includes a step of calculating a maximum absolute value of the voltage of the voltage pulse, and in (e-2), the first voltage value is 10% or more of the maximum value, and the second voltage value is 90% or less of the maximum value.

[0102] (Supplementary Note 7) The plasma processing method according to any one of Supplementary Notes 3 to 6, wherein the variable resistor is connected in series to the voltage pulse generating unit and the substrate supporting unit in the path.

[0103] (Supplementary Note 8) The plasma processing method according to any one of Supplementary Notes 3 to 7, wherein the variable inductor is connected in series to the voltage pulse generating unit and the substrate supporting unit in the path.

[0104] (Supplementary Note 9) The plasma processing method according to any one of Supplementary Notes 1 to 8, further comprising the step of (f) setting values ​​of the one or more parameters, wherein (d) comprises adjusting at least one of the resistance value of the variable resistor and the inductance of the variable inductor based on the set values ​​of the one or more parameters set in (f).

[0105] (Supplementary Note 10) The plasma processing method according to Supplementary Note 9, wherein (f) comprises: (f-1) setting at least one value of the one or more parameters to a first value; and (f-2) setting at least one value of the at least one parameter to a second value different from the first value; and (d) comprises: (d-1) adjusting at least one of a resistance value of the variable resistor and an inductance of a variable inductor based on the first value; and (d-2) adjusting at least one of a resistance value of the variable resistor and an inductance of the variable inductor based on the second value; and wherein the one or more parameters comprise at least one selected from the group consisting of a pressure in the chamber, an elapsed time of the plasma processing, a frequency of the source RF signal, a power of the source RF signal, and a flow rate of the processing gas.

[0106] (Supplementary Note 11) The plasma processing method according to Supplementary Note 10, wherein in (f), the one or more parameters include a frequency of the source RF signal, and in (a), the method includes: (a-1) generating plasma by a source RF signal having a first frequency based on the first value set in (f-1), and (a-2) generating plasma by a source RF signal having a second frequency lower than the first frequency based on the second value set in (f-2).

[0107] (Supplementary Note 12) The plasma processing method according to Supplementary Note 11, wherein, while the step (a-1) is being performed, in the step (d-1), the resistance value of the variable resistor is adjusted to a first resistance value; and while the step (a-2) is being performed, in the step (d-2), the resistance value of the variable resistor is adjusted to a second resistance value higher than the first resistance value.

[0108] (Supplementary Note 13) The plasma processing method according to Supplementary Note 12, wherein the voltage pulse of the bias DC signal includes a plurality of inflection points, and a maximum voltage difference between the plurality of inflection points while the step (a-1) is being performed is greater than a maximum voltage difference between the plurality of inflection points while the step (a-2) is being performed.

[0109] (Supplementary Note 14) The plasma processing method according to Supplementary Note 12, wherein active species contained in the plasma generated while (a-1) and (a-2) are being performed are directed toward the substrate by (c), and the directionality of the active species toward the substrate while (a-1) is being performed is lower than the directionality of the active species toward the substrate while (a-2) is being performed.

[0110] (Supplementary Note 15) The plasma processing method according to Supplementary Note 12, wherein while (a-1) is being performed, by-products generated from the processing gas are deposited on the substrate, and while (a-2) is being performed, at least a portion of the by-products are removed by plasma generated from the processing gas.

[0111] (Supplementary Note 16) The plasma processing method according to any one of Supplementary Notes 1 to 15, wherein the resistance value is 5 Ω to 500 Ω.

[0112] (Supplementary Note 17) The plasma processing method according to any one of Supplementary Notes 1 to 16, wherein the inductance is 1 μH to 50 μH.

[0113] (Supplementary Note 18) A plasma processing apparatus comprising a chamber and a control unit, and performing plasma processing on a substrate based on one or more parameters, wherein the control unit is configured to execute the following controls: (a) generating plasma from a processing gas supplied to the chamber by a source RF signal; (b) generating a bias DC signal by a voltage pulse generating unit, the bias DC signal including a sequence of voltage pulses; (c) supplying the bias DC signal from the voltage pulse generating unit to a substrate support disposed in the chamber via a path electrically connecting the voltage pulse generating unit to the substrate support; and (d) adjusting at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path, based on values ​​of the one or more parameters.

[0114] The exemplary embodiments described above may be modified in various ways without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment may be added to other embodiments within the scope of ordinary creativity of a person skilled in the art. Also, some components in one embodiment may be replaced with corresponding components in other embodiments.

[0115] 1: Plasma processing apparatus, 11: Substrate support, 33: Voltage pulse generating unit, 60: Path, 70: Variable resistor, 80: Variable inductor

Claims

1. A plasma processing method for performing plasma processing on a substrate in a plasma processing apparatus having a chamber, the plasma processing being performed based on one or more parameters, the plasma processing method comprising: (a) generating a plasma from a processing gas supplied to the chamber by a source RF signal; (b) generating a bias DC signal by a voltage pulse generating unit, the bias DC signal including a sequence of voltage pulses; (c) supplying the bias DC signal from the voltage pulse generating unit to a substrate support disposed in the chamber via a path electrically connecting the substrate support and the voltage pulse generating unit; and (d) adjusting at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path based on values ​​of the one or more parameters.

2. The plasma processing method of claim 1, further comprising a step (e) of measuring the values ​​of the one or more parameters, and (d) comprises adjusting at least one of the resistance value of the variable resistor and the inductance of the variable inductor based on the measured values ​​of the one or more parameters measured in (e).

3. The plasma processing method according to claim 2, wherein the one or more parameters include a voltage of the voltage pulse, and (e) comprises the steps of: (e-1) measuring a voltage value of the voltage pulse as a value of the one or more parameters; and (e-2) calculating at least one of a rise time and a fall time of the voltage pulse based on the voltage value of the voltage pulse measured in (e-1), and in (d), at least one of the resistance value of the variable resistor and the inductance of the variable inductor is adjusted based on at least one of the rise time or fall time of the voltage pulse, and the voltage value of the voltage pulse.

4. The plasma processing method according to claim 3, wherein in (e-1), the voltage of the voltage pulse is measured in the path between the variable resistor and the variable inductor and the substrate support.

5. The plasma processing method according to claim 3, wherein in (e-2), the rise time or fall time of the voltage pulse is the time required for the absolute value of the voltage of the voltage pulse to change from a first voltage value to a second voltage value higher than the first voltage value.

6. The plasma processing method according to claim 5, wherein (e-1) includes a step of calculating a maximum absolute value of the voltage of the voltage pulse, and in (e-2), the first voltage value is 10% or more of the maximum value, and the second voltage value is 90% or less of the maximum value.

7. The plasma processing method according to claim 3, wherein the variable resistor is connected in series to the voltage pulse generating section and the substrate supporting section in the path.

8. The plasma processing method according to claim 3, wherein the variable inductor is connected in series with the voltage pulse generating section and the substrate supporting section in the path.

9. The plasma processing method of claim 1, further comprising the step of (f) setting values ​​of the one or more parameters, and (d) comprising adjusting at least one of the resistance value of the variable resistor and the inductance of the variable inductor based on the set values ​​of the one or more parameters set in (f).

10. The plasma processing method of claim 9, wherein the step (f) comprises: (f-1) setting at least one value of the one or more parameters to a first value; and (f-2) setting at least one value of the at least one parameter to a second value different from the first value; and the step (d) comprises: (d-1) adjusting at least one of a resistance value of the variable resistor and an inductance of a variable inductor based on the first value; and (d-2) adjusting at least one of a resistance value of the variable resistor and an inductance of the variable inductor based on the second value; and the one or more parameters comprise at least one selected from the group consisting of a pressure in the chamber, an elapsed time of the plasma processing, a frequency of the source RF signal, a power of the source RF signal, and a flow rate of the processing gas.

11. The plasma processing method according to claim 10, wherein in (f), the one or more parameters include a frequency of the source RF signal, and in (a), the method includes: (a-1) generating plasma by a source RF signal having a first frequency based on the first value set in (f-1); and (a-2) generating plasma by a source RF signal having a second frequency lower than the first frequency based on the second value set in (f-2).

12. The plasma processing method according to claim 11, wherein while (a-1) is being performed, in (d-1), the resistance value of the variable resistor is adjusted to a first resistance value, and while (a-2) is being performed, in (d-2), the resistance value of the variable resistor is adjusted to a second resistance value higher than the first resistance value.

13. The plasma processing method of claim 12, wherein the voltage pulse of the bias DC signal includes a plurality of inflection points, and a maximum voltage difference between the plurality of inflection points while (a-1) is being performed is greater than a maximum voltage difference between the plurality of inflection points while (a-2) is being performed.

14. The plasma processing method of claim 12, wherein active species contained in the plasma generated while (a-1) and (a-2) are being performed are directed toward the substrate by (c), and the lineality with which the active species move toward the substrate while (a-1) is being performed is lower than the lineality with which the active species move toward the substrate while (a-2) is being performed.

15. The plasma processing method according to claim 12, wherein while (a-1) is being performed, products generated from the processing gas are deposited on the substrate, and while (a-2) is being performed, at least a portion of the products are removed by plasma generated from the processing gas.

16. The plasma processing method according to any one of claims 1 to 15, wherein the resistance value is 5 Ω to 500 Ω.

17. The plasma processing method according to any one of claims 1 to 15, wherein the inductance is 1 μH to 50 μH.

18. A plasma processing apparatus comprising a chamber and a control unit, and performing plasma processing on a substrate based on one or more parameters, wherein the control unit is configured to execute the following controls: (a) generating plasma from a processing gas supplied to the chamber by a source RF signal; (b) generating a bias DC signal by a voltage pulse generating unit, the bias DC signal including a sequence of voltage pulses; (c) supplying the bias DC signal from the voltage pulse generating unit to a substrate support disposed in the chamber via a path electrically connecting the voltage pulse generating unit to the substrate support; and (d) adjusting at least one of a resistance value of a variable resistor and an inductance of a variable inductor electrically connected to the path, based on values ​​of the one or more parameters.

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