Plasma treatment device, power supply system, and plasma treatment method

Abstract

The disclosed plasma treatment device includes a chamber, a substrate support unit, an RF power supply, a matching unit, and a control unit. The matching unit includes a variable capacitor connected between the RF power supply and a high-frequency electrode. The RF power supply is configured to change the source frequency of a source RF signal in accordance with the degree of reflection of the source RF signal so as to reduce the degree of reflection during a plasma processing period. The control unit is configured to control the variable capacitor of the matching device so as to set the capacitance of the variable capacitor to a preset capacitance such that a variation range of the source frequency in at least a steady period within the plasma processing period is included in a recommended variation range for the source frequency of the RF power supply.

Description

Plasma processing apparatus, power supply system, and plasma processing method

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to a plasma processing apparatus, a power supply system, and a plasma processing method.

[0002] A plasma processing apparatus is used in plasma processing of a substrate. In the plasma processing apparatus, bias high frequency power is used to attract ions from a plasma generated in a chamber to the substrate. Patent Document 1 listed below discloses a plasma processing apparatus in which the power level and frequency of the bias high frequency power are modulated.

[0003] Japanese Patent Application Laid-Open No. 2009-246091

[0004] The present disclosure provides techniques for increasing the power efficiency of an RF power supply in a plasma processing apparatus and reducing the degree of reflection of a source RF signal.

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, an RF power supply, a matching box, and a controller. The substrate support is disposed within the chamber. The RF power supply is configured to supply a source RF signal to a radio frequency electrode to generate plasma from a gas within the chamber. The matching box includes a variable capacitor connected between the RF power supply and the radio frequency electrode. The RF power supply is configured to vary the source frequency of the source RF signal in response to a degree of reflection from a load of the RF power supply during a plasma processing period for performing plasma processing on a substrate on the substrate support, in order to reduce the degree of reflection. The plasma processing period includes a plasma ignition period, a steady-state period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady-state period. The controller is configured to control the variable capacitor to set a capacitance of the variable capacitor to a predetermined capacitance for the plasma processing such that a fluctuation range of the source frequency during at least the steady-state period is within a recommended fluctuation range of the source frequency of the RF power supply.

[0006] According to one exemplary embodiment, it is possible to increase the power efficiency of an RF power supply in a plasma processing apparatus and reduce the degree of reflection of a source RF signal.

[0007] 6A and 6B are timing charts showing an example of a source RF signal and an electric bias in a plasma processing apparatus according to an exemplary embodiment; FIG. 6B is a diagram showing an example of a table; FIG. 6C is a flowchart showing an example of a process STb in a plasma processing method according to an exemplary embodiment; FIG. 6D is a flowchart showing another example of a process STb in a plasma processing method according to an exemplary embodiment; and FIG. 6E is a block diagram of a computer (a type of circuit) capable of realizing various control aspects described herein.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0009] 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.

[0010] The plasma generating 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), electron cyclotron resonance (ECR) plasma, helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generating units may be used, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units. 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. Therefore, AC signals include RF (Radio Frequency) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0011] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various steps described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various steps 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 realized by, for example, a computer 2a. The control unit 2 may include a processing unit 2a1, a memory unit 2a2, and a communication interface 2a3. The functions performed by the processing unit 2a1 described in this disclosure may be implemented in circuitry or processing circuitry, including general-purpose processors, application-specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), CPUs (Central Processing Units), conventional circuitry, and / or combinations thereof, programmed to perform the described functions. A processor is considered to be a circuit or processing circuit including transistors and other circuitry. The processor may also be a programmed processor that executes a program stored in the memory unit 2a2. This program may be stored in the memory 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 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).In this disclosure, a circuit, unit, or means is hardware that is programmed to implement or configured to implement a described function. The hardware may be any hardware described in this disclosure or any hardware that is programmed to implement or known to implement the described function. If the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software used to configure the hardware and / or processor.

[0012] 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.

[0013] 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 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.

[0014] 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.

[0015] 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 may 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 chuck electrode 1111b disposed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also referred to as 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. Note that the annular region 111b may be formed on 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. At least one bias electrode electrically connected to or coupled to a power supply 31 and / or a power supply 32 (described later) may be disposed within the ceramic member 1111a. In this case, the at least one bias electrode functions as a lower electrode. Alternatively, the conductive member of the base 1110 and the bias electrode within 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 to or coupled to the bias electrode within the ceramic member 1111a, and the first RF generation unit 31a (described later) is electrically connected to or coupled to the conductive member of the base 1110. The electrostatic chuck electrode 1111b may function as a lower electrode. The substrate support 11 therefore comprises at least one bottom electrode.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] The power supply system 30 includes a power supply 31 electrically connected or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected 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 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.

[0021] The power supply 31 includes a first RF generator 31a and a second RF generator 31b. The first RF generator 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 generator 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 150 MHz. In one embodiment, the first RF generator 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.

[0022] The second RF generator 31b is electrically connected or coupled to at least one lower electrode and configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generator 31b is electrically connected or coupled to at least one lower electrode via at least one impedance matcher. When the first RF generator 31a is electrically connected or coupled to a lower electrode, the second RF generator 31b may be electrically connected or coupled to the same lower electrode or 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 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.

[0023] The power supply system 30 may also include a power supply 32 electrically connected or coupled to the plasma processing chamber 10. The power supply 32 includes a first voltage generator 32a and a second voltage generator 32b. In one embodiment, the first voltage generator 32a is electrically connected or coupled to at least one lower electrode and configured to generate a first voltage signal. The generated first voltage signal is applied to the at least one lower electrode. In one embodiment, the second voltage generator 32b is electrically connected or coupled to at least one upper electrode and configured to generate a second voltage signal. The generated second voltage signal is applied to the at least one upper electrode.

[0024] In various embodiments, the first and / or second voltage signals may be pulsed. In this case, the first voltage generator 32a and / or the second voltage generator 32b function as a voltage pulse generator 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 includes multiple cycles, each cycle including a burst of voltage pulses during a first period and a constant reference voltage during a second period. That is, the bursts of voltage pulses are repeated in the sequence of voltage pulses. The absolute value of the voltage level of the voltage pulses is greater than the absolute value of the voltage level of the reference voltage. The voltage pulses may have an arbitrary waveform, such as a rectangular, trapezoidal, triangular, or combination thereof, and the arbitrary waveform may vary over time. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses within one cycle. The first and second voltage generating units 32a and 32b may be provided in addition to the power supply 31, or the first voltage generating unit 32a may be provided instead of the second RF generating unit 31b.

[0025] 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.

[0026] Reference will now be made to FIG. 3, which is a diagram illustrating a plasma processing apparatus according to an exemplary embodiment. As illustrated in FIG. 3, the plasma processing apparatus 1 includes a power supply system 50 that is used as the above-described power supply system 30. The power supply system 50 includes an RF power supply 51, a matching box 53, and a control unit 50c. The power supply system 50 may further include a bias power supply 52. ​​The power supply system 50 may also include at least one sensor, such as a sensor 55 or a sensor 56.

[0027] The RF power supply 51 includes the first RF generating unit 31a described above. The RF power supply 51 is configured to supply a source RF signal HF (source radio frequency power) to generate plasma from the gas in the chamber 10. The source RF signal HF has a source frequency fs. That is, the source RF signal HF has a sinusoidal waveform whose frequency is the source frequency fs. The source frequency fs can be a frequency within a range of 10 MHz to 150 MHz.

[0028] The RF power supply 51 is electrically connected to the high-frequency electrode via a matching box 53 and is configured to supply a source RF signal HF to the high-frequency electrode. The high-frequency electrode may be provided within the substrate support 11. The high-frequency electrode may be at least one electrode provided within the conductive member or ceramic member 1111a of the base 1110. Alternatively, the high-frequency electrode may be an upper electrode. When the source RF signal HF is supplied to the high-frequency electrode, plasma is generated from the gas in the chamber 10.

[0029] The matching circuit 53 has a variable impedance. The variable impedance of the matching circuit 53 is set so as to reduce reflection of the source RF signal HF from the load. The matching circuit 53 can be controlled by, for example, the control unit 50c. Note that the control unit 50c may be the control unit 2 or may be a control circuit included in the power supply system 50 separate from the control unit 2.

[0030] In one embodiment, the matching box 53 may include a variable capacitor 531 and a variable capacitor 532. One end of the variable capacitor 531 is connected to an electrical path that electrically connects the RF power supply 51 and the radio-frequency electrode to each other. The other end of the variable capacitor 531 is connected to ground. The variable capacitor 532 is connected between the RF power supply 51 and the radio-frequency electrode. Specifically, one end of the variable capacitor 532 is electrically connected to the RF power supply 51, and the other end of the variable capacitor 532 is electrically connected to the radio-frequency electrode.

[0031] The variable capacitor 531 and / or the variable capacitor 532 may be a mechanically controlled capacitor. Alternatively, the variable capacitor 531 and / or the variable capacitor 532 may be an electronically controlled capacitor. FIG. 4 is a diagram showing an example of a matching box. In the example of FIG. 4, the variable capacitor 532 is configured as an electronically controlled capacitor. In an electronically controlled variable capacitor, like the variable capacitor 532 shown in FIG. 4, multiple series circuits, each including a series connection of a capacitor and a switch, are connected in parallel. In an electronically controlled variable capacitor, the capacitance of the variable capacitor can be changed by switching the switches of the multiple series circuits ON and OFF (i.e., closed and open).

[0032] Returning to FIG. 3 , the bias power supply 52 is electrically coupled to the substrate support 11. The bias power supply 52 is electrically connected to a bias electrode in the substrate support 11. The bias electrode may be at least one electrode provided in the conductive member or ceramic member 1111a of the base 1110. The bias electrode may also be a radio frequency electrode. The bias power supply 52 is configured to periodically supply an electric bias EB to the bias electrode in order to attract ions from the plasma in the chamber 10 to the substrate W on the substrate support 11. The bias power supply 52 includes the above-mentioned second RF generator 31b or first voltage generator 32a.

[0033] Reference will now be made to FIG. 5 in conjunction with FIG. 3. FIG. 5 is a diagram illustrating an example of the waveform of the electric bias. The bias power supply 52 is configured to periodically supply an electric bias EB having a waveform period Cb to the bias electrode. That is, the electric bias EB is applied to the bias electrode in each of a plurality of waveform periods Cb, which are repetitions of the waveform period Cb. The waveform period Cb is defined by the bias frequency. The bias frequency is, for example, not less than 50 kHz and not more than 27 MHz. The time length of the waveform period Cb is the reciprocal of the bias frequency. The bias frequency may be not more than 13.56 MHz or not more than 400 kHz.

[0034] The electrical bias EB may be a bias RF signal generated by the second RF generating unit 31b, i.e., a bias RF signal LF (bias high frequency power) having a bias frequency. That is, the electrical bias EB may have a sinusoidal waveform whose frequency is the bias frequency. In this case, the bias power supply 52 is electrically connected to the bias electrode via a matching box 54. The variable impedance of the matching box 54 is set to reduce reflection of the bias RF signal LF from the load.

[0035] Alternatively, the electric bias EB may include a voltage pulse VP generated by the first voltage generator 32a. The voltage pulse VP is applied to the bias electrode in a waveform period Cb. The voltage pulse VP is applied to the bias electrode periodically at time intervals equal to the time length of the waveform period Cb. That is, a sequence of voltage pulses VP is applied to the bias electrode. The waveform of the voltage pulse VP may be a square wave, a triangular wave, or any other waveform. The polarity of the voltage pulse VP is set so as to generate a potential difference between the substrate W and the plasma and attract ions from the plasma to the substrate W. The voltage pulse VP is applied to the bias electrode so that the waveform period Cb includes a period during which the potential of the substrate W is negative. The voltage pulse VP applied to the bias electrode may have a negative potential, a positive potential, or a potential that changes between a positive potential and a negative potential. The voltage pulse VP may be a negative voltage pulse or a negative DC voltage pulse. When the electric bias EB is a voltage pulse VP, the plasma processing apparatus 1 does not need to include the matching box 54 .

[0036] Hereinafter, reference will be made to FIGS. 6( a) and 6(b) along with FIGS. 3 and 5. FIGS. 6(a) and 6(b) are timing charts of an example of a source RF signal and an electric bias in a plasma processing apparatus according to an exemplary embodiment. In these figures, "ON" of the source RF signal HF indicates that the source RF signal HF is being supplied, and "OFF" of the source RF signal HF indicates that the supply of the source RF signal HF is stopped. Also, in FIG. 6(b), "HIGH" of the source RF signal HF indicates that a source RF signal HF having a power level higher than the power level indicated by "LOW" is being supplied. Also, in these figures, "ON" of the electric bias EB indicates that the electric bias EB is being supplied, and "OFF" of the electric bias EB indicates that the supply of the electric bias EB is stopped. In (b) of Figure 6, "HIGH" of the electric bias EB indicates that an electric bias EB having a level higher than the level indicated by "LOW" is being supplied. When the electric bias EB is a bias RF signal LF, the level of the electric bias EB is the power level of the bias RF signal LF. When the electric bias EB includes a voltage pulse VP, the electric bias EB has a higher level as the energy of ions attracted to the substrate W increases. When the electric bias EB includes a voltage pulse VP, the level of the electric bias EB may be the absolute value of the voltage level of the voltage pulse VP in the negative direction relative to a reference voltage (e.g., 0 V).

[0037] The RF power supply 51 is configured to supply a source RF signal HF in parallel with the periodic supply of an electric bias EB from the bias power supply 52. ​​As shown in Fig. 6A, the electric bias EB and the source RF signal HF may be supplied simultaneously and continuously from the start to the end of a process or step. That is, a continuous wave of the electric bias EB and a continuous wave of the source RF signal HF may be supplied in parallel.

[0038] Alternatively, as shown in (b) of FIG. 6, the pulse of the electric bias EB and the pulse of the source RF signal HF may be supplied periodically with a pulse period Cp (a pulse generation period). In this case, the pulse of the electric bias EB and the pulse of the source RF signal HF may be supplied in synchronization with each other in a pulse period PP within each pulse period Cp. That is, the pulse period PP of each of a plurality of pulse periods Cp (in (b) of FIG. 6, the pulse period PP １ , PP ２ , PP ３ , ...), a pulse of the electric bias EB and a pulse of the source RF signal HF may be supplied simultaneously. Each pulse period PP includes a plurality of waveform cycles Cb. That is, in each pulse period PP, the electric bias EB is supplied periodically. The pulse of the electric bias EB may be an ON / OFF pulse that alternately assumes a supply state (ON state in (b) of FIG. 6) and a stop state (OFF state in (b) of FIG. 6). Alternatively, the pulse of the electric bias EB may be a HIGH / LOW pulse that alternately assumes a high-level state (HIGH state in (b) of FIG. 6) and a low-level state (LOW state in (b) of FIG. 6). Furthermore, the pulse of the source RF signal HF may be an ON / OFF pulse that alternately assumes a supply state (ON state in (b) of FIG. 6) and a stop state (OFF state in (b) of FIG. 6). Alternatively, the pulse of the source RF signal HF may be a HIGH / LOW pulse that alternates between a high-level state (HIGH state in FIG. 6(b)) and a low-level state (LOW state in FIG. 6(b)). The power level of the source RF signal HF may be modulated during a period when the source RF signal HF is ON. The power level of the source RF signal HF may be modulated during a period when the power level of the source RF signal HF is HIGH. The power level of the source RF signal HF may be modulated during a period when the power level of the source RF signal HF is LOW.

[0039] 3, the sensor 55 is a VI sensor (voltage / current measuring sensor) configured to measure the voltage and current of the source RF signal HF and output a voltage signal representing the voltage and a current signal representing the current. The sensor 56 is a directional coupler configured to measure the forward wave and reflected wave of the source RF signal HF and output a forward wave signal representing the forward wave and a reflected wave signal representing the reflected wave. The voltage signal and current signal from the sensor 55 and the forward wave signal and reflected wave signal from the sensor 56 are input to the control unit 50c.

[0040] The RF power supply 51 is configured to change the source frequency fs of the source RF signal HF in accordance with the degree of reflection so as to reduce the degree of reflection of the source RF signal HF from the load of the RF power supply 51 during the plasma processing period. The plasma processing period is a period during which plasma processing is performed on the substrate on the substrate support 11. The plasma processing period includes a plasma ignition period IP, a steady-state period SP during which the plasma is in a steady state, and a plasma rise-up period LP between the ignition period IP and the steady-state period SP. The ignition period IP is a period that starts from a state in which no plasma is generated in the chamber 10 and continues until the plasma is ignited. The steady-state period SP is a period during which the plasma is stably generated in the chamber 10. The rise-up period LP is a period that continues from the time the plasma is ignited until the plasma is stably generated.

[0041] In the example of FIG. 6(a), the ignition period IP starts at the start of supply of the source RF signal HF. In the example of FIG. 6(a), the steady period SP ends at the end of supply of the continuous wave of the source RF signal HF. In the example of FIG. 6(b), each pulse period PP includes the steady period SP. In the example of FIG. 6(b), each of the second and subsequent pulse periods PP may include a rising period LP before the steady period SP. Also, in the example of FIG. 6(b), at least the first pulse period PP １includes an ignition period IP before the rise period LP. In the example of Figure 6(b), each of the second and subsequent pulse periods PP includes an ignition period IP before the rise period LP if the plasma is extinguished before the start of the pulse period PP. In the example of Figure 6(b), each of the second and subsequent pulse periods PP does not include an ignition period IP if the plasma is not extinguished before the start of the pulse period PP.

[0042] The degree of reflection may be determined from the phase difference between the voltage and current of the source RF signal HF or the difference between the load impedance and a predetermined impedance (e.g., 50Ω). The phase difference between the voltage and current of the source RF signal HF and the difference between the load impedance and a predetermined impedance are determined in the control unit 50c or the RF power supply 51 using the voltage signal and current signal from the sensor 55. Alternatively, the degree of reflection may be determined from the power of the reflected wave of the source RF signal HF or the value of the ratio of the power of the reflected wave to the power of the forward wave (i.e., the reflectivity). The power of the reflected wave and the reflectivity of the source RF signal HF are determined in the control unit 50c or the RF power supply 51 using the forward wave signal and reflected wave signal from the sensor 56.

[0043] In one embodiment, each of the sensors 55 and 56 may have frequency characteristics whose measurement results depend on the source frequency fs. In this case, the control unit 50c may obtain a corrected voltage signal and a corrected current signal by multiplying the voltage signal and the current signal from the sensor 55 by a correction coefficient corresponding to the source frequency fs or adding a correction amount corresponding to the source frequency fs to each of the voltage signal and the current signal from the sensor 55. The degree of reflection may be determined from the corrected voltage signal and the corrected current signal. The control unit 50c may also obtain a corrected forward wave signal and a corrected reflected wave signal by multiplying the forward wave signal and the reflected wave signal from the sensor 56 by a correction coefficient corresponding to the source frequency fs or adding a correction amount corresponding to the source frequency fs to each of the forward wave signal and the reflected wave signal. The degree of reflection may be determined from the corrected reflected wave signal and the corrected forward wave signal. The correction coefficient or correction amount corresponding to the source frequency fs may be stored in a table in a storage device such as the storage device 50m described below. The table stores correction coefficients or correction amounts corresponding to multiple source frequencies for each signal to be corrected. The control unit 50c may determine the correction coefficient or correction amount by referring to a table, and obtain a correction signal such as a corrected voltage signal, a corrected current signal, a corrected reflected wave signal, or a corrected forward wave signal.

[0044] The RF power supply 51 can determine the source frequency fs that reduces the degree of reflection of the source RF signal HF through a feedback process. In the feedback process, the RF power supply 51 divides each repeat period RC included in the series of repeat periods RC into multiple phase periods PH. The repeat period RC is a repeat period of the source RF signal HF or the electrical bias EB. In the example of FIG. 6(a), the series of repeat periods RC is a series of waveform periods Cb. In the example of FIG. 6(b), the series of repeat periods RC may be a series of pulse periods Cp. Alternatively, in the example of FIG. 6(b), the series of repeat periods RC may be a series of pulse periods Cp for a first subperiod in a pulse period PP, and may be a series of waveform periods Cb for a second subperiod after the first subperiod in the pulse period PP. Note that each waveform period Cb in the series of waveform periods Cb is divided into N phase periods PH, as shown in FIG. Furthermore, each of the plurality of waveform periods Cb included in each pulse period Cp in the series of pulse periods Cp is also divided into N phase periods PH.

[0045] The RF power supply 51 determines the source frequency fs for each phase period PH included in the series of repetition periods RC so as to reduce the degree of reflection in accordance with the degree of reflection in the same phase period PH in the past in the series of repetition periods RC. For example, the RF power supply 51 determines the source frequency fs for each phase period PH included in the series of repetition periods RC so as to reduce the degree of reflection in accordance with the tendency of the degree of reflection obtained by using a different source frequency fs in the same phase period PH in the past in the series of repetition periods RC.

[0046] Returning to FIG. 3 , the control unit 50c controls the variable capacitor 532 to set the capacitance of the variable capacitor 532 to a capacitance preset for the plasma processing performed during the plasma processing period so that the fluctuation range of the source frequency fs during at least the steady period SP falls within the recommended fluctuation range. The recommended fluctuation range is the recommended fluctuation range of the source frequency fs of the RF power supply 51. The recommended fluctuation range is a range of the source frequency fs that allows the RF power supply 51 to operate with high power efficiency, and is specific to the RF power supply 51 and is predetermined. Note that the control unit 50c may also control the variable capacitor 532 to set the capacitance of the variable capacitor 532 to a capacitance preset for the plasma processing performed during the plasma processing period so that the fluctuation range of the source frequency fs during the period including the rise period LP and the steady period SP or the period including the ignition period IP, the rise period LP, and the steady period SP falls within the recommended fluctuation range.

[0047] In one embodiment, the capacitance set by the control unit 50c to the variable capacitor 532 may be stored in a table. In this case, the plasma processing apparatus 1 or the power supply system 50 further includes a memory device 50m. The memory device 50m may be part of the control unit 50c. The memory device 50m may be the memory unit 2a2. The memory device 50m includes a table 50t. FIG. 7 is a diagram illustrating an example of the table. As shown in FIG. 7, the table 50t stores the capacitance of the variable capacitor 532 in association with multiple identifiers that respectively identify multiple plasma processes that can be performed in the plasma processing apparatus 1. The control unit 50c may identify the capacitance of the variable capacitor 532 corresponding to the identifier of the plasma process to be performed during the plasma processing period by referring to the table 50t. The control unit 50c may set the capacitance of the variable capacitor 532 to the identified capacitance. Note that the capacitance of the variable capacitor 532 may be experimentally determined by actually performing each of the multiple plasma processes using the plasma processing apparatus 1 so as to maintain the fluctuation range of the source frequency fs during the plasma processing period within the recommended fluctuation range.

[0048] In one embodiment, if the source frequency fs becomes a frequency outside the recommended fluctuation range during execution of plasma processing in the plasma processing period, the control unit 50c may change the capacitance of the variable capacitor 532 so that the fluctuation range of the source frequency fs is included within the recommended fluctuation range.

[0049] In one embodiment, when the source frequency fs becomes a frequency outside the recommended fluctuation range during the execution of plasma processing in the plasma processing period, the control unit 50c may detect an abnormal state of the plasma processing apparatus 1. When an abnormal state is detected, the control unit 50c may execute abnormality processing such as emitting an alarm, displaying an alarm, or stopping the plasma processing.

[0050] According to the plasma processing apparatus 1 described above, the source frequency fs is adjusted so as to reduce the degree of reflection of the source RF signal HF during the plasma processing period. Furthermore, the capacitance of the variable capacitor 532 is set so as to maintain the fluctuation range of the source frequency fs within the recommended fluctuation range at least during the steady period SP within the plasma processing period. Therefore, according to the plasma processing apparatus 1, it is possible to increase the power efficiency of the RF power supply 51 and reduce the degree of reflection of the source RF signal HF.

[0051] A plasma processing method according to one exemplary embodiment will be described below with reference to Fig. 8. Fig. 8 is a flow chart showing the plasma processing method according to one exemplary embodiment. The plasma processing method shown in Fig. 8 (hereinafter referred to as "method MT") is performed in a state where a substrate W is placed on a substrate support 11 in a plasma processing apparatus 1. In each step of method MT, each part of the plasma processing apparatus 1 can be controlled by the control unit 2 or the control unit 50c.

[0052] The method MT includes steps STa and STb. In step STa, the capacitance of the variable capacitor 532 is set to a capacitance that is preset for the plasma processing performed during the plasma processing period. For details about setting the capacitance of the variable capacitor 532, please refer to the above description related to the plasma processing apparatus 1.

[0053] In the subsequent step STb, plasma processing is performed. Each of Figures 9 and 10 is a flow chart showing an example of step STb in a plasma processing method according to an exemplary embodiment. In step STb1 of the step STb, a source RF signal HF is supplied to generate plasma in the chamber 10. In step STb2 of the step STb, the degree of reflection of the source RF signal HF is determined. In step STb3 of the step STb, the source frequency fs for each phase period PH is adjusted according to the degree of reflection of the source RF signal HF. For the source frequency fs for each phase period PH, please refer to the description of the feedback process above.

[0054] In the subsequent step STbJ, it is determined whether the fluctuation range of the source frequency fs is within the recommended fluctuation range. If the fluctuation range of the source frequency fs is within the recommended fluctuation range, the processing from step STb1 is repeated.

[0055] If it is determined in step STbJ that the fluctuation range of the source frequency fs is not included in the recommended fluctuation range, the capacitance of the variable capacitor 532 is adjusted in step STb4, as shown in Fig. 9. For example, as described above, if the source frequency fs becomes a frequency outside the recommended fluctuation range during execution of plasma processing in the plasma processing period, the capacitance of the variable capacitor 532 may be changed so that the fluctuation range of the source frequency fs is included in the recommended fluctuation range.

[0056] Alternatively, if it is determined in step STbJ that the fluctuation range of the source frequency fs is not included in the recommended fluctuation range, an abnormal state of the plasma processing apparatus 1 may be detected in step STb5 as shown in Fig. 10. If an abnormal state is detected in step STb5, abnormality handling such as generation of an alarm sound, display of an alarm, or termination of plasma processing may be performed as described above.

[0057] Hereinafter, examples of circuits (control circuits) that can constitute the control unit 2 and / or the control unit 50c will be described.

[0058] 11 illustrates a block diagram of a computer (a type of circuit) capable of implementing various control aspects described herein. Furthermore, the control aspects of the present disclosure may be embodied as a system, method, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions recorded thereon that cause one or more processing devices to perform aspects of the present embodiments.

[0059] A computer-readable storage medium may be a tangible device capable of storing instructions for use by an instruction execution device (processor). The computer-readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of these devices. More specific examples of computer-readable storage media include, but are not limited to, a floppy disk, a hard disk, a solid-state drive (SSD), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash), a static random access memory (SRAM), a compact disk (CD or CD-ROM), a digital versatile disk (DVD), a memory card, or a memory stick (and suitable combinations thereof). In this disclosure, a computer-readable storage medium should not be construed as a transitory signal itself, such as, for example, an electric wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse passing through a fiber optic cable), or an electrical signal transmitted over an electrical wire.

[0060] The computer-readable program instructions described in this disclosure can be downloaded from a computer-readable storage medium to an appropriate computing or processing device, or can be downloaded to an external computer or external storage device via a global network (i.e., the Internet), a local area network, a wide area network, and / or a wireless network, including copper wires, fiber optics, wireless communications, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing or processing device can receive the computer-readable program instructions from the network and transfer the computer-readable program instructions for storage in a computer-readable storage medium within the computing or processing device.

[0061] Computer-readable program instructions for carrying out operations of the present disclosure may include machine language instructions and / or microcode. These instructions may be compiled or interpreted from source code written in any combination of one or more programming languages, including assembly language, Basic, Fortran, Java, Python, R, C, C++, C#, etc. The computer-readable program instructions may execute entirely on a user's personal computer, notebook computer, tablet, or smartphone, or entirely on a remote computer or computer server, or on any combination of these computing devices. The remote computer or computer server may be connected to one or more of the user's devices via a computer network, including a local area network, a wide area network, or a global network (i.e., the Internet). Alternatively, electronic circuitry, including, for example, programmable logic circuits, field programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), may use information from the computer-readable program instructions to configure or customize the electronic circuitry to execute the computer-readable program instructions and implement aspects of the present disclosure.

[0062] Aspects of the present disclosure are described herein with reference to flowcharts and block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present disclosure. Those skilled in the art will understand that each block of the flowcharts and block diagrams, and combinations of blocks in the flowcharts and block diagrams, can be implemented by computer-readable program instructions.

[0063] Computer-readable program instructions that can implement the systems and methods described herein may be supplied to one or more processors (and / or one or more cores within a processor) of a general-purpose computer, special-purpose computer, or other programmable device. The instructions, executed via the processor of the computer or other programmable device, can thereby create a machine-implemented system for implementing the functionality embodied in the flowcharts and block diagrams of this disclosure. These computer-readable program instructions may also be stored on a computer-readable storage medium that can direct a computer, programmable device, and / or other device to function in a particular manner. A computer-readable storage medium having instructions stored thereon is an article of manufacture that includes instructions that implement aspects of the functionality embodied in the flowcharts and block diagrams of this disclosure.

[0064] The computer-readable program instructions may also be loaded onto a computer, other programmable apparatus, or other device and cause the computer, other programmable apparatus, or other device to perform a series of operating steps to realize a computer-implemented process. Thus, the instructions executing on the computer, other programmable apparatus, or other device may realize the functions specifically illustrated in the flowcharts and block diagrams of this disclosure.

[0065] 11 is a functional block diagram illustrating a network system 800 in which one or more computers and servers are networked. In one embodiment, the hardware and software environment illustrated in FIG. 11 may serve as an exemplary platform for implementing the software and / or methods of the present disclosure.

[0066] 11 , a network system 800 may include, but is not limited to, a computer 805, a network 810, a remote computer 815, a web server 820, a cloud storage server 825, and a computer server 830. In some embodiments, multiple instances of one or more of the functional blocks illustrated in FIG.

[0067] Further details of computer 805 are shown in Figure 11. The functional blocks illustrated within computer 805 are merely shown to provide an example of functional architecture and are not intended to be exhaustive. Also, although details are not shown for remote computer 815, web server 820, cloud storage server 825, and computer server 830, these computers and devices may also include functionality similar to that shown with respect to computer 805.

[0068] The computer 805 may be a personal computer (PC), a desktop computer, a laptop computer, a tablet computer, a netbook computer, a personal digital assistant (PDA), a smartphone, or other programmable electronic device capable of communicating with other devices on the network 810.

[0069] Computer 805 may include a processing unit 835, a bus 837, memory 840, non-volatile storage 845, a network interface 850, a peripherals interface 855, and a display interface 865. In some embodiments, these functions may be implemented as individual electronic subsystems (integrated circuit chips or combinations of chips and associated devices), while in other embodiments, some combinations of functions may be implemented on a single chip (also called a system-on-chip or SoC).

[0070] Processing unit 835 may be one or more single-chip or multi-chip microprocessors, such as those designed and / or manufactured by Intel Corporation, Advanced Micro Devices, Inc. (AMD), ARM Holdings, Apple Computer, etc. Examples of microprocessors include Intel's Celeron, Pentium, Core i3, Core i5, Core i7, AMD's Opteron, Phenom, Athlon, Turion, Ryzen, ARM's Cortex-A, Cortex-R, Cortex-M, etc.

[0071] Bus 837 may be a proprietary or industry standard high speed parallel or serial peripheral interconnect bus such as ISA, PCI, PCI Express (PCI-e), AGP, etc.

[0072] The memory 840 and the non-volatile storage 845 may be computer-readable storage media. The memory 840 may include any suitable volatile storage device, such as dynamic random access memory (DRAM) and static random access memory (SRAM). The non-volatile storage 845 may include one or more of a floppy disk, a hard disk, a solid-state drive (SSD), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash), a compact disk (CD or CD-ROM), a digital versatile disk (DVD), a memory card, or a memory stick.

[0073] The program 848 may be a collection of machine-readable instructions and / or machine-readable data stored in at least one memory, such as non-volatile storage 845, and used to create, manage, and control certain software functions described in detail in this disclosure and illustrated in the figures. In some embodiments, memory 840 may be much faster than non-volatile storage 845. In that case, the program 848 may be transferred from non-volatile storage 845 to memory 840 and then executed by processing unit 835. The program 848 includes computer program code. In one implementation, the at least one memory containing the computer program code comprises at least one processing unit (such as the processing circuitry described below) for implementing the control processes and claimed developments of the present disclosure.

[0074] Computer 805 may be able to communicate and interact with other computers over network 810 using network interface 850. Network 810 may be, for example, a local area network (LAN), a wide area network (WAN) such as the Internet, or a combination thereof, and may include wired, wireless, or fiber optic connections. In general, network 810 may be any combination of connections and protocols that support communication between two or more computers and related devices.

[0075] The peripheral interface 855 may enable input and output of data via other devices that may be locally connected to the computer 805. For example, the peripheral interface 855 may enable connection to external devices 860. The external devices 860 may include devices such as a keyboard, mouse, keypad, touch screen, and / or other suitable input devices. The external devices 860 may also include portable computer-readable storage media such as thumb drives, portable optical or magnetic disks, and memory cards. Software and data (e.g., program 848) used to implement embodiments of the present disclosure may be stored on such portable computer-readable storage media. In this case, the software may be loaded into non-volatile storage 845 or directly into memory 840 via the peripheral interface 855. The peripheral interface 855 may use industry-standard connections, such as RS-232 or Universal Serial Bus (USB), to connect to the external devices 860.

[0076] Display interface 865 may connect computer 805 to display device 870. In some embodiments, display device 870 may be used to present a command line or graphical user interface to a user of computer 805. Display interface 865 may connect to display device 870 using one or more proprietary or industry standard connections, such as VGA, DVI, DisplayPort, HDMI, etc.

[0077] As described above, network interface 850 facilitates communication with other computing or storage systems or devices external to computer 805. Software programs and data described herein may be downloaded to non-volatile storage 845 via network interface 850 and network 810 from, for example, remote computer 815, web server 820, cloud storage server 825, or computer server 830. Furthermore, the systems and methods described herein may be implemented by one or more computers connected to computer 805 via network interface 850 and network 810. For example, in some embodiments, the systems and methods described herein may be implemented by remote computer 815, computer server 830, or a combination of computers interconnected over network 810.

[0078] Data, datasets, and / or databases used in embodiments of the systems and methods described in this disclosure may be stored on or downloaded from a remote computer 815, web server 820, cloud storage server 825, computer server 830.

[0079] As used herein, a circuit may be defined as one or more of the following: an electronic component (e.g., a semiconductor device), multiple electronic components connected directly to each other or interconnected via electronic communication, a computer, a network of computer devices, a remote computer, a web server, a cloud storage server, or a computer server. For example, one or more of a computer, a remote computer, a web server, a cloud storage server, or a computer server may each be included as a component within the circuit or may include circuitry. In some embodiments, multiple instances of one or more of these components may be used, and each of multiple instances of one or more of these components may also be included within the circuit or include circuitry. In some embodiments, a circuit represented by a network system may include a serverless computing system that supports virtualized hardware resources. A circuit represented by a computer may be a personal computer (PC), desktop computer, laptop computer, tablet computer, netbook computer, personal digital assistant (PDA), smartphone, or other programmable electronic device capable of communicating with other devices on a network. A circuit may be a general-purpose computer, a special-purpose computer, or other programmable device described herein that includes one or more processing units. Each processing unit may be one or more single-chip or multi-chip microprocessors. The one or more processing units may be considered processing circuits or circuits because they incorporate transistors and other circuitry. The circuitry may implement the systems and methods described in this disclosure based on computer-readable program instructions that are provided to one or more processing units (and / or one or more cores within a processing unit) of one or more general-purpose computers, special-purpose computers, or other programmable devices described herein. This may create a machine-implemented system for implementing the functionality embodied in the flowcharts and block diagrams of this disclosure, with instructions contained within the circuitry or executed via one or more processing units of a programmable device that includes the circuitry.Alternatively, a circuit may be a pre-programmed structure, such as a programmable logic device or an application specific integrated circuit. A circuit is considered a circuit whether used alone or in combination with other programmable or pre-programmed circuits.

[0080] Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.

[0081] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0082] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E17] below.

[0083] [E1] A plasma processing apparatus comprising: a chamber; a substrate support within the chamber; an RF power supply configured to supply a source RF signal to a radio frequency electrode to generate plasma from a gas within the chamber; a matching box including a variable capacitor connected between the RF power supply and the radio frequency electrode; and a control unit, wherein the RF power supply is configured to change a source frequency of the source RF signal in accordance with a degree of reflection of the source RF signal from a load of the RF power supply during a plasma processing period in which plasma processing is performed on a substrate on the substrate support, so as to reduce the degree of reflection of the source RF signal from the load of the RF power supply, the plasma processing period including a plasma ignition period, a steady period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady period, and the control unit is configured to control the variable capacitor to set a capacitance of the variable capacitor to a capacitance preset for the plasma processing such that a fluctuation range of the source frequency during at least the steady period is included within a recommended fluctuation range of the source frequency of the RF power supply.

[0084] [E2] The plasma processing apparatus according to E1, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing so that a fluctuation range of the source frequency during a period including the rise period and the steady period is within a recommended fluctuation range of the source frequency of the RF power supply.

[0085] [E3] The plasma processing apparatus according to E1, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing so that a fluctuation range of the source frequency during a period including the ignition period, the rise period, and the steady-state period is included within a recommended fluctuation range of the source frequency of the RF power supply.

[0086] [E4] The plasma processing apparatus of any one of E1 to E3, further comprising a bias power supply electrically coupled to the substrate support and configured to periodically supply an electrical bias to attract ions from the plasma to a substrate on the substrate support, wherein the RF power supply is configured to adjust the source frequency for each phase period within a repeating cycle of the source RF signal or the electrical bias to reduce the degree of reflection of the source RF signal in accordance with the degree of reflection of the source RF signal in a previous identical phase period.

[0087] [E5] The plasma processing apparatus according to E4, wherein the repetition period is a waveform period of the electrical bias.

[0088] [E6] The plasma processing apparatus according to E4, wherein the repetition period is a pulse generation period of the source RF signal.

[0089] [E7] The plasma processing apparatus according to any one of E1 to E6, further comprising a storage device having a table that stores the capacitance of the variable capacitor in correspondence with each of a plurality of identifiers that respectively identify a plurality of plasma processes, and the control unit is configured to identify the capacitance of the variable capacitor corresponding to the identifier of the plasma process to be performed by referring to the table.

[0090] [E8] The plasma processing apparatus according to any one of E1 to E7, wherein the control unit is configured to detect an abnormal state when the fluctuation range of the source frequency includes a frequency that exceeds the recommended fluctuation range at least during the steady period while the plasma processing is being performed.

[0091] [E9] A power supply system comprising: an RF power supply configured to supply a source RF signal to a radio frequency electrode to generate plasma from a gas in a chamber of a plasma processing apparatus; a matching box including a variable capacitor connected between the RF power supply and the radio frequency electrode; and a control unit, wherein the RF power supply is configured to change a source frequency of the source RF signal in accordance with a degree of reflection so as to reduce a degree of reflection of the source RF signal from a load of the RF power supply during a plasma processing period in which plasma processing is performed on a substrate on a substrate support in the chamber, the plasma processing period including a plasma ignition period, a steady period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady period, and the control unit is configured to control the variable capacitor to set a capacitance of the variable capacitor to a capacitance preset for the plasma processing so that a fluctuation range of the source frequency during at least the steady period is included within a recommended fluctuation range of the source frequency of the RF power supply.

[0092] [E10] The power supply system according to E9, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing so that the fluctuation range of the source frequency during a period including the rise period and the steady period is within a recommended fluctuation range of the source frequency of the RF power supply.

[0093] [E11] The power supply system according to E9, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing so that a fluctuation range of the source frequency during a period including the ignition period, the rise period, and the steady-state period is within a recommended fluctuation range of the source frequency of the RF power supply.

[0094] [E12] The power supply system of any one of E9 to E11, further comprising a bias power supply electrically coupled to the substrate support and configured to periodically supply an electrical bias to attract ions from the plasma to a substrate on the substrate support, wherein the RF power supply is configured to adjust the source frequency for each phase period within a repeating cycle of the source RF signal or the electrical bias to reduce a degree of reflection of the source RF signal in response to a degree of reflection of the source RF signal in a previous phase period of the same phase.

[0095] [E13] The power supply system of E12, wherein the repeating period is a waveform period of the electrical bias.

[0096] [E14] The power supply system according to E12, wherein the repetition period is a period during which pulses of the source RF signal occur.

[0097] [E15] The power supply system according to any one of E9 to E14, further comprising a storage device having a table that stores the capacitance of the variable capacitor in correspondence with each of a plurality of identifiers that respectively identify a plurality of plasma processes, and the control unit is configured to identify the capacitance of the variable capacitor that corresponds to the identifier of the plasma process to be performed by referring to the table.

[0098] [E16] The power supply system according to any one of E9 to E15, wherein the control unit is configured to detect an abnormal state when the fluctuation range of the source frequency includes a frequency that exceeds the recommended fluctuation range at least during the steady-state period while the plasma processing is being performed.

[0099] [E17] (a) a step of setting the capacitance of a variable capacitor of a matching box in a plasma processing apparatus, the plasma processing apparatus comprising: a chamber; a substrate support within the chamber; an RF power supply configured to supply a source RF signal to a radio frequency electrode; and the matching box including the variable capacitor connected between the RF power supply and the radio frequency electrode; and (b) a step of performing plasma processing on a substrate on the substrate support during a plasma processing period, wherein (b) includes a step of supplying the source RF signal from the RF power supply to the radio frequency electrode to generate plasma from a gas in the chamber, and during the plasma processing period, the RF power supply changes a source frequency of the source RF signal in accordance with a degree of reflection of the source RF signal from a load of the RF power supply so as to reduce the degree of the reflection, and the plasma processing period includes a plasma ignition period, a steady period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady period, In the plasma processing method (a), the capacitance of the variable capacitor is set to a capacitance that is preset for the plasma processing so that a fluctuation range of the source frequency during at least the steady period is included within a recommended fluctuation range of the source frequency of the RF power supply.

[0100] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0101] 1... plasma processing apparatus, 10... chamber, 11... substrate support portion, 50... power supply system, 51... RF power supply, 52... bias power supply, 53... matching box, 532... variable capacitor, 2, 50c... control portion.

Claims

1. A plasma processing apparatus comprising: a chamber; a substrate support within the chamber; an RF power supply configured to supply a source RF signal to a radio frequency electrode to generate plasma from a gas within the chamber; a matching box including a variable capacitor connected between the RF power supply and the radio frequency electrode; and a control unit, wherein the RF power supply is configured to change the source frequency of the source RF signal in accordance with a degree of reflection of the source RF signal from a load of the RF power supply during a plasma processing period in which plasma processing is performed on a substrate on the substrate support, so as to reduce the degree of reflection of the source RF signal from the load of the RF power supply, the plasma processing period including a plasma ignition period, a steady period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady period, and the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing such that a fluctuation range of the source frequency during at least the steady period is within a recommended fluctuation range of the source frequency of the RF power supply.

2. The plasma processing apparatus of claim 1, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance that is preset for the plasma processing so that the fluctuation range of the source frequency during a period including the rise period and the steady period is within a recommended fluctuation range of the source frequency of the RF power supply.

3. The plasma processing apparatus of claim 1, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance that is preset for the plasma processing so that the fluctuation range of the source frequency during a period including the ignition period, the rise period, and the steady-state period is within a recommended fluctuation range of the source frequency of the RF power supply.

4. The plasma processing apparatus of any one of claims 1 to 3, further comprising a bias power supply electrically coupled to the substrate support and configured to periodically supply an electrical bias to attract ions from the plasma to a substrate on the substrate support, wherein the RF power supply is configured to adjust the source frequency for each phase period within a repeating cycle of the source RF signal or the electrical bias so as to reduce the degree of reflection of the source RF signal in accordance with the degree of reflection of the source RF signal in a previous identical phase period.

5. The plasma processing apparatus of claim 4, wherein said repeating period is a waveform period of said electrical bias.

6. The plasma processing apparatus of claim 4, wherein said repetition period is the period of occurrence of pulses of said source RF signal.

7. A plasma processing apparatus as described in any one of claims 1 to 3, further comprising a memory device having a table that stores the capacitance of the variable capacitor in correspondence with each of a plurality of identifiers that respectively identify a plurality of plasma processes, and the control unit is configured to identify the capacitance of the variable capacitor corresponding to the identifier of the plasma process to be performed by referring to the table.

8. A plasma processing apparatus according to any one of claims 1 to 3, wherein the control unit is configured to detect an abnormal state when the fluctuation range of the source frequency includes a frequency that exceeds the recommended fluctuation range at least during the steady-state period during which the plasma processing is being performed.

9. A power supply system comprising: an RF power supply configured to supply a source RF signal to a radio frequency electrode to generate plasma from a gas in a chamber of a plasma processing apparatus; a matching box including a variable capacitor connected between the RF power supply and the radio frequency electrode; and a control unit, wherein the RF power supply is configured to change the source frequency of the source RF signal in accordance with the degree of reflection so as to reduce the degree of reflection of the source RF signal from a load of the RF power supply during a plasma processing period in which plasma processing is performed on a substrate on a substrate support in the chamber, the plasma processing period including a plasma ignition period, a steady period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady period, and the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing so that the fluctuation range of the source frequency during at least the steady period is within a recommended fluctuation range of the source frequency of the RF power supply.

10. The power supply system of claim 9, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance that is preset for the plasma processing so that the fluctuation range of the source frequency during a period including the rise period and the steady period is within a recommended fluctuation range of the source frequency of the RF power supply.

11. The power supply system of claim 9, wherein the control unit is configured to control the variable capacitor to set the capacitance of the variable capacitor to a capacitance preset for the plasma processing so that the fluctuation range of the source frequency during a period including the ignition period, the rise period, and the steady-state period is within a recommended fluctuation range of the source frequency of the RF power supply.

12. The power supply system of any one of claims 9 to 11, further comprising a bias power supply electrically coupled to the substrate support and configured to periodically supply an electrical bias to attract ions from the plasma to a substrate on the substrate support, wherein the RF power supply is configured to adjust the source frequency for each phase period within a repeating cycle of the source RF signal or the electrical bias to reduce a degree of reflection of the source RF signal in response to a degree of reflection of the source RF signal in a previous phase period of the same phase.

13. The power supply system of claim 12, wherein said repeating period is a waveform period of said electrical bias.

14. The power supply system of claim 12, wherein said repetition period is the occurrence period of pulses of said source RF signal.

15. A power supply system as claimed in any one of claims 9 to 11, further comprising a storage device having a table that stores the capacitance of the variable capacitor in correspondence with each of a plurality of identifiers that respectively identify a plurality of plasma processes, and the control unit is configured to identify the capacitance of the variable capacitor that corresponds to the identifier of the plasma process to be performed by referring to the table.

16. A power supply system according to any one of claims 9 to 11, wherein the control unit is configured to detect an abnormal state when the fluctuation range of the source frequency includes a frequency that exceeds the recommended fluctuation range at least during the steady-state period while the plasma processing is being performed.

17. (a) a step of setting the capacitance of a variable capacitor of a matcher in a plasma processing apparatus, the plasma processing apparatus comprising: a chamber; a substrate support within the chamber; an RF power supply configured to supply a source RF signal to a radio frequency electrode; and the matcher including the variable capacitor connected between the RF power supply and the radio frequency electrode; and (b) a step of performing plasma processing on a substrate on the substrate support during a plasma processing period, wherein (b) includes a step of supplying the source RF signal from the RF power supply to the radio frequency electrode to generate plasma from a gas in the chamber, and during the plasma processing period, the RF power supply changes the source frequency of the source RF signal in accordance with the degree of reflection from a load of the RF power supply so as to reduce the degree of reflection of the source RF signal, and the plasma processing period includes a plasma ignition period, a steady period in which the plasma is in a steady state, and a plasma rise period between the ignition period and the steady period, In the plasma processing method (a), the capacitance of the variable capacitor is set to a capacitance that is preset for the plasma processing so that a fluctuation range of the source frequency during at least the steady period is included within a recommended fluctuation range of the source frequency of the RF power supply.

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