Plasma processing method and plasma processing apparatus

Abstract

A plasma processing method for performing plasma processing on a substrate includes: acquiring, for each control cycle of a bias signal, a parameter about an impedance matching state when the bias signal is supplied to an electrode provided on a substrate support portion; and determining the frequency f (n) of the bias signal in the nth control period by the following formula (1): f (n) = f (n-1)-[delta] f / [delta] P * Pr (n-1) * F (1).

Description

Technical Field

[0001] This invention relates to plasma processing methods and plasma processing apparatus. Background Technology

[0002] Patent document 1 discloses a frequency control method, which is a method of applying a high-frequency pulse for plasma excitation to a plasma source, so that the frequency of the high-frequency pulse is moved to a higher frequency than when the pulsed plasma is in a stable state of excitation during plasma ignition.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 10-064696 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The technology of this invention optimizes the RF power supply conditions during plasma ignition.

[0008] Technical means to solve the problem

[0009] One aspect of the present invention is a plasma processing method for plasma processing a substrate, comprising: acquiring parameters regarding the impedance matching state when the bias signal is supplied to an electrode disposed on a substrate support at each control cycle of a bias signal; and determining the frequency f(n) of the bias signal in the nth control cycle by the following equation (1).

[0010] f(n)=f(n-1)-Δf / ΔP×Pr(n-1)×F···(1)

[0011] In this context, the frequency of the (n-2)th control cycle is set to f(n-2), the frequency of the (n-1)th control cycle is set to f(n-1), the parameter of the (n-2)th control cycle is set to Pr(n-2), the parameter of the (n-1)th control cycle is set to Pr(n-1), Δf=f(n-2)-f(n-1), ΔP=Pr(n-2)-Pr(n-1), where n is an integer greater than or equal to 3, and F is a constant.

[0012] Invention Effects

[0013] According to the present invention, the conditions for RF power supply during plasma ignition can be optimized. Attached Figure Description

[0014] Figure 1 This is an explanatory diagram showing a structural example of a plasma processing system according to one embodiment.

[0015] Figure 2 This is a cross-sectional view showing a structural example of a plasma processing apparatus according to one embodiment.

[0016] Figure 3 This is a flowchart illustrating an example of a plasma processing method according to one embodiment.

[0017] Figure 4 This is a flowchart illustrating the outline of the bias signal supply method in the first embodiment.

[0018] Figure 5 It is a graph showing the behavior of the bias signal, bias frequency, and reflected wave power in the bias signal supply method of the first embodiment.

[0019] Figure 6 This is a flowchart outlining the method for determining the bias frequency in the bias signal supply method of the first embodiment.

[0020] Figure 7 This is a flowchart illustrating the outline of the bias signal supply method in the second embodiment.

[0021] Figure 8 It is a graph showing the behavior of the bias signal, bias frequency, and reflected wave power in the bias signal supply method of the second embodiment.

[0022] Figure 9 This is a flowchart outlining the method for determining the bias frequency in the bias signal supply method of the second embodiment.

[0023] Figure 10 This is a flowchart illustrating the outline of the bias signal supply method in the third embodiment.

[0024] Figure 11 This is a flowchart outlining the method for determining the bias frequency in the bias signal supply method of the third embodiment.

[0025] Figure 12 This is a flowchart illustrating the source signal supply method of the fourth embodiment.

[0026] Figure 13 This is a flowchart outlining the method for determining the position of the stable matched unit in the source signal supply method of the fourth embodiment.

[0027] Figure 14 This is a flowchart outlining the scanning of the source frequency at the stable matched unit position in the source signal supply method of the fourth embodiment.

[0028] Figure 15This is a flowchart illustrating an example of bias signal control in the source signal supply method of the fourth embodiment.

[0029] Figure 16 It is a graph representing the reflected wave power or luminous intensity during plasma ignition in the source signal supply method of the fourth embodiment.

[0030] Figure 17 This is a flowchart illustrating another example of bias signal control in the source signal supply method of the fourth embodiment.

[0031] Figure 18 It is a graph representing the reflected wave power or luminous intensity during plasma ignition in the source signal supply method of the fourth embodiment.

[0032] Figure 19 This is a flowchart illustrating yet another example of bias signal control in the source signal supply method of the fourth embodiment.

[0033] Figure 20 This is a flowchart illustrating an example of source signal control in the source signal supply method of the fourth embodiment.

[0034] Figure 21 This is a flowchart illustrating an example of the matching unit position control in the source signal supply method of the fourth embodiment. Detailed Implementation

[0035] In the manufacturing process of semiconductor devices, a processing module housing a semiconductor wafer (hereinafter referred to as a "substrate") is brought into a depressurized state, and various processing steps are performed to perform prescribed processing on the substrate. Furthermore, these multiple processing steps are performed, for example, using a substrate processing apparatus in which multiple processing modules are arranged around a shared transport module.

[0036] As a substrate processing apparatus, the plasma processing apparatus disclosed in Patent Document 1 can be cited as an example. In a parallel-plate type plasma processing apparatus, a substrate is introduced into an airtight plasma processing space including an upper electrode and a lower electrode, and plasma is generated with the required gas type and gas pressure. Then, plasma processing, including etching, is performed on the substrate by attracting ions from the generated plasma onto the substrate. The generation of plasma and the attraction of plasma ions to the substrate are achieved by supplying a source signal and / or a bias signal, which are RF power (high-frequency power), to the upper electrode and / or the lower electrode.

[0037] When RF power is applied to the upper and / or lower electrodes, plasma is generated. However, during plasma ignition, as the plasma transitions from a non-plasma state to a plasma state and the molecular density increases (hereinafter referred to as plasma growth), the impedance changes. When this impedance change causes an impedance mismatch between the RF power supply and the plasma processing space, a reflected RF power wave is generated from the plasma processing space. If the power of the reflected wave exceeds the reflected wave tolerance of the RF power supply, it can sometimes lead to damage to the RF power supply, or the generated plasma taking a long time to stabilize. Although existing technologies include matching circuits to achieve impedance matching between the RF power supply and the plasma processing space, these circuits cannot achieve complete matching and are prone to generating significant reflections. This is because existing matching circuits require a motor to change the position of the matching device for second-level control, which cannot track impedance changes on the order of microseconds.

[0038] Furthermore, as disclosed in Patent Document 1, a technique has been proposed to excite pulsed plasma for substrate processing by applying pulses of RF power controlled by ON / OFF or HIGH / LOW to the upper and / or lower electrodes. When the pulse frequency increases (the ON / OFF interval or HIGH / LOW interval becomes shorter), the number of plasma ignitions also increases, and the total power of the reflected waves during plasma ignition increases. The inventors have found that as the total power of the reflected waves increases, various problems arise, such as reduced power efficiency and increased load on the RF power supply.

[0039] Furthermore, the longer the time required for impedance matching and plasma ignition, the greater the total power of the reflected waves. The inventors discovered that by reducing the power of the reflected waves and shortening the time required for plasma ignition, the total power of the reflected waves can be reduced.

[0040] Therefore, the technology of the present invention can optimize the RF power supply conditions during plasma ignition. Specifically, the reflected wave power is reduced by optimizing the bias signal supply, and the time required for plasma ignition is shortened by optimizing the source signal supply.

[0041] Hereinafter, the structure of the plasma processing system of this embodiment will be described with reference to the accompanying drawings. Furthermore, in this specification, elements having substantially the same functional structure are labeled with the same reference numerals, thereby omitting repeated descriptions.

[0042] Figure 1This is a diagram illustrating a structural example 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 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. Furthermore, the plasma processing chamber 10 has at least one gas supply port for supplying at least one type of processing gas to the plasma processing space and at least one gas exhaust port for discharging gas from the plasma processing space. The gas supply port is connected to the gas supply unit 20 (described later), and the gas exhaust port is connected to the exhaust system 40 (described later). The substrate support 11 is disposed within the plasma processing space and has a substrate support surface for supporting a substrate.

[0043] The plasma generation unit 12 is configured to generate plasma from at least one type of process gas supplied to the plasma processing space. The plasma generated in the plasma processing space can be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR), helicon wave plasma (HWP), or surface wave plasma (SWP), etc. Alternatively, various types of plasma generation units, including AC (alternating current) plasma generation units and DC (direct current) plasma generation units, can be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes 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.

[0044] The control unit 2 is capable of processing computer-executable commands for causing the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 can be configured to control various elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 can be configured to perform various control actions by reading a program from the storage unit 2a2 and executing the read program. The program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The retrieved program is stored in the storage unit 2a2 and read and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 can communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0045] Hereinafter, a structural example of a capacitively coupled plasma processing device 1, which is an example of a plasma processing device 1, will be described. Figure 2 This is a diagram illustrating a structural example of a capacitively coupled plasma processing device 1.

[0046] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. Additionally, the plasma processing apparatus 1 includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a spray head 13. The substrate support 11 is disposed within the plasma processing chamber 10. The spray head 13 is disposed above the substrate support 11. In one embodiment, the spray head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the spray head 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The spray head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0047] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 when viewed from above. The substrate W is disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the main body portion 111 in such a way that it surrounds the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as an annular support surface for supporting the ring assembly 112.

[0048] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive component. The conductive component 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 component 1111a and an electrostatic electrode 1111b disposed within the ceramic component 1111a. The ceramic component 1111a has a central region 111a. In one embodiment, the ceramic component 1111a also has an annular region 111b. Alternatively, other components surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating component, may also have an annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating component, or on both the electrostatic chuck 1111 and the annular insulating component. Alternatively, at least one RF / DC electrode coupled to the RF power supply 31 and / or DC power supply 32 (described later) may be disposed within the ceramic component 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When the bias signal and / or DC signal (described later) are supplied to the at least one RF / DC electrode, the RF / DC electrode is also referred to as a bias electrode. Furthermore, the conductive components of the base 1110 and the at least one RF / DC electrode may also function as multiple lower electrodes. Additionally, the electrostatic electrode 1111b may also function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0049] The ring assembly 112 includes one or more annular components. In one embodiment, the one or more annular components 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.

[0050] Additionally, the substrate support 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate W to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are disposed within the ceramic component 1111a of the electrostatic chuck 1111. Furthermore, the substrate support 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0051] The spray head 13 is configured to introduce at least one type of process gas from the gas supply unit 20 into the plasma processing space 10s. The spray head 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 is introduced into the plasma processing space 10s through the gas diffusion chamber 13b and the multiple gas inlets 13c. Additionally, the spray head 13 includes at least one upper electrode. Furthermore, the gas inlet unit may also include, in addition to the spray head 13, one or more side gas injectors (SGIs) installed at one or more openings formed in the sidewall 10a.

[0052] 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 type of processing gas from corresponding gas sources 21 to spray heads 13 via corresponding flow controllers 22. Each flow controller 22 may, for example, include a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device for modulating or pulsed the flow rate of the at least one type of processing gas.

[0053] 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 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 signal to at least one lower electrode, a bias potential can be generated on the substrate W, attracting the ionic components of the generated plasma to the substrate W.

[0054] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is configured to be coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit to generate a source signal (source RF power) for plasma generation. In one embodiment, the source signal has a frequency in the range of 10MHz to 150MHz. In one embodiment, the first RF generation unit 31a may also be configured to generate multiple source signals with different frequencies. The generated one or more source signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0055] The second RF generation unit 31b is configured to couple to at least one lower electrode via at least one impedance matching circuit to generate a bias signal (bias RF power). The frequency of the bias signal may be the same as or different from the frequency of the source signal. In one embodiment, the bias signal has a frequency lower than the frequency of the source signal. In one embodiment, the bias signal has a frequency in the range of 100kHz to 60MHz. In one embodiment, the second RF generation unit 31b may also be configured to generate multiple bias signals with different frequencies. The generated one or more bias signals are supplied to at least one lower electrode. In addition, in various embodiments, at least one of the source signal and the bias signal can be pulsed by ON / OFF control or HIGH / LOW control.

[0056] In one implementation, both the source signal and the bias signal can be pulsed. In this case, the ON / OFF or HIGH / LOW times of the source signal can be supplied synchronously with the ON / OFF or HIGH / LOW times of the bias signal. Alternatively, the ON time of the source signal can precede the ON time of the bias signal.

[0057] In one embodiment, the RF power supply 31 is configured to be controllable to change the frequency of the bias signal. In this case, the RF power supply 31 may be a known variable frequency power supply whose frequency is variably controlled in the second RF generation unit 31b. Alternatively, a known inverter configured to be controllable to change the frequency of the bias signal may be provided in the supply path of the bias signal from the RF power supply 31 to the lower electrode. In another embodiment, the RF power supply 31 is configured to be controllable to change the frequency of the source signal. In this case, the RF power supply 31 may be a known variable frequency power supply whose frequency is variably controlled in the first RF generation unit 31a. Alternatively, a known inverter configured to be controllable to change the frequency of the source signal may be provided in the supply path of the source signal from the RF power supply 31 to the upper electrode and / or the lower electrode.

[0058] Additionally, the power supply 30 may include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generating unit 32a and a second DC generating unit 32b. In one embodiment, the first DC generating unit 32a is configured to be connected to at least one lower electrode to generate a first DC signal. The generated first DC signal is applied to at least one lower electrode. In one embodiment, the second DC generating unit 32b is configured to be connected to at least one upper electrode to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0059] In various embodiments, the first and second DC signals can be pulsed. In this case, a voltage pulse sequence is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses can have rectangular, trapezoidal, triangular, or combinations thereof pulse waveforms. In one embodiment, a waveform generation unit for generating a voltage pulse sequence from the DC signals is connected between the first DC generation unit 32a and at least one lower electrode. Therefore, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the voltage pulse generation unit is constituted by the second DC generation unit 32b and the waveform generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses can be positive or negative. In addition, the voltage pulse sequence can include one or more positive voltage pulses and one or more negative voltage pulses in one cycle. Furthermore, the first and second DC generation units 32a and 32b can be provided together with the RF power supply 31, or the first DC generation unit 32a can be provided instead of the second RF generation unit 31b. In one embodiment, the waveform generation unit is configured to be controllable to vary the frequency of the generated voltage pulses. In this case, the waveform generation unit may have a known switching mechanism that variably controls the frequency of the voltage pulses.

[0060] In one embodiment, a unit is included to measure the power (hereinafter referred to as reflected wave power) of the power reflected from various loads, including the upper electrode and the lower electrode, when power (hereinafter referred to as the supply wave) is supplied from the RF power source 31. In this case, the RF power source 31 may include this unit. Alternatively, it may be provided on the supply path of the supply wave from the RF power source 31 to the upper electrode and / or the lower electrode. In this case, the unit may be a reflected wave detector 33a provided on the supply path of the supply wave of the upper electrode and / or a reflected wave detector 33b provided on the supply path of the supply wave of the lower electrode.

[0061] The exhaust system 40 can be connected, for example, to a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space 10s is regulated using the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0062] <Plasma Treatment Methods>

[0063] Next, the plasma processing method MT1 will be described. The plasma processing method MT1 of the present invention can be executed, for example, in the plasma processing system described above. Specifically, when the RF power supply 31 is a variable frequency power supply, frequency variation control can be performed in the RF power supply 31. Furthermore, when an inverter is provided, frequency variation control can be performed in the inverter. Additionally, in obtaining the reflected power as described below, the reflected power value can be obtained by measuring it using a measurement unit provided in the RF power supply 31 or on the power supply path from the RF power supply 31 to the upper electrode and / or lower electrode. Control and measurement instructions, recording, and calculation steps can be performed in the control unit 2. Furthermore, in the present invention, the source power, bias power, and reflected wave power are given by the source signal, bias signal, and the square of the amplitude of the reflected wave, respectively.

[0064] The following uses Figure 3 The plasma treatment method MT1 is described. Figure 3 This is a flowchart illustrating an outline of a plasma processing method MT1 according to one embodiment. First, a substrate is fed into the chamber (ST1). Next, the process recipe is read, and a process is started (ST2). Next, gas is supplied to the chamber with the required gas type and pressure (ST3). Next, a source signal is supplied (ST4). The method for supplying the source signal in step ST4 will be described later. Next, a bias signal is supplied (ST5). The method for supplying the bias signal in step ST5 will be described later. Alternatively, steps ST4 and ST5 can be performed simultaneously. Afterward, a process is ended (ST6). Next, it is determined whether to perform another process using a different process recipe (ST7). If so, return to step ST2, read another process recipe, and perform another process, repeating steps ST2 to ST7. If no other process is performed in step ST7, the substrate is removed from the chamber, and the plasma processing method MT1 ends.

[0065] Next, the method for supplying a bias signal to the lower electrode in plasma processing method MT1 (hereinafter referred to as the bias signal supply method) will be described. The following bias signal supply methods MT10 to MT30 can be performed as step ST5 in the plasma processing method MT1 described above. However, it is not limited to this. For example, process gas can be supplied to the plasma processing space before the process begins, and then any one of the following bias signal supply methods MT10 to MT30 can be performed to confirm the plasma ignition conditions in the process beforehand. Afterwards, plasma processing method MT1 is performed, and in step ST5, the bias signal is supplied using the pre-recorded plasma ignition conditions as described above.

[0066] <First Implementation Method>

[0067] The bias signal supply method MT10 of the first embodiment will be described. In this embodiment, the frequency of the bias signal (hereinafter referred to as the bias frequency) is varied in each control cycle to obtain the desired bias frequency. A control cycle refers to a division of control in units from the execution of one control that changes the value of the bias frequency to the execution of another control that changes the value of the bias frequency to another value. Specifically, in this embodiment, a control cycle is defined as a division of control in units of steps ST100 to ST108 described below.

[0068] First, use Figure 4 The overall flow of the bias signal supply method MT10 in the first embodiment will be described. First, the initial value of the control cycle n is set to (n=3), and the nth control cycle (ST100) begins. Next, the nth bias frequency f is determined and recorded. B (n)(ST102). The nth bias frequency f B The method for determining (n) will be described later. Next, the determined nth bias frequency f is applied. BThe bias signal (n) is then applied (ST104). Next, the power of the nth reflected wave Pr(n) reflected from the load is measured and recorded when this bias signal is supplied (ST106). Then, the value of the nth reflected wave power Pr(n) is compared with a threshold value to determine the magnitude relationship (ST108). The threshold value can be a value predetermined according to the process formula and read in step ST108. In step ST108, if the value of the nth reflected wave power Pr(n) is above the threshold value, the nth control cycle ends, and (n=n+1) is set, and the next control cycle begins (ST110). In the (n+1)th control cycle, steps ST100 to ST108, which were performed in the nth control cycle, are executed again. Thereafter, for any natural number k, steps ST100 to ST108 are repeatedly executed in the (n+k)th control cycle. In step ST108, if the value of the nth reflected wave power Pr(n) is less than the required threshold, the nth bias frequency f is adjusted. B (n) is recorded as the stable bias frequency f BC (ST112). Afterwards, a stable bias frequency f was continued to be supplied. BC The bias signal (ST114).

[0069] In the above, the threshold can be a past actual value regarding plasma stability used for each process. In this case, the threshold has a required initial value, which can be reduced by a specified percentage each control cycle, or it can vary with the required time elapsed, or these can be arbitrarily selected and combined to vary it. By determining the threshold in this way, the impedance matching state can be improved as the control cycle or time elapses. Furthermore, the threshold in another embodiment described later can also be determined in the same way.

[0070] Figure 5 This is a graph summarizing the changes in the ON / OFF (HIGH / LOW) of the bias signal, the bias frequency, and the reflected wave power per unit time when the bias signal supply method MT10 of the first embodiment is executed. In steps ST100 to ST110, through cyclic control, the reflected wave power decreases as the bias frequency changes. The bias frequency at the moment when the reflected wave power becomes less than a threshold is recorded as the stable bias frequency f. BC (ST112), and continues to supply applications with a stable bias frequency f BC The bias signal (ST114).

[0071] Next, the nth bias frequency f is determined in the bias signal supply method MT10 of the first embodiment. B The steps (ST102) of (n) will be explained in detail. Figure 6 It meansFigure 4 The nth bias frequency f is determined in the middle. B A flowchart detailing step ST102 of (n) is provided. First, the constant F (ST120) is determined. The constant F can be recorded as a value predetermined according to the process formulation and read in step ST120. Next, the (n-2)th bias frequency f is read. B (n-2), the (n-1)th bias frequency f B The power of the (n-1), (n-2)th reflected wave Pr(n-2), and (n-1)th reflected wave Pr(n-1) (ST122). Next, the change in bias frequency Δf is calculated by the following equation (1), the change in reflected wave power ΔP is calculated by the following equation (2), and the nth bias frequency f is determined and recorded by the following equation (3). B (n).

[0072] Δf=f B (n-2)-f B (n-1)···(1)

[0073] ΔP=Pr(n-2)-Pr(n-1)···(2)

[0074] f B (n)=f B (n-1)-Δf / ΔP×Pr(n-1)×F···(3)

[0075] As an example, the aforementioned constant F can be determined as follows. Plasma is generated in the plasma processing chamber 10, in which a dummy wafer has been previously fed, and the dummy wafer is processed. At this time, a constant F for plasma stability is searched over time. The constant F for plasma stability is searched in such a way that a sufficiently small constant F is initially used so that the change in bias frequency determined by the above equations (1) to (3) is small, and while gradually increasing the constant F, a constant F of an appropriate magnitude that does not lose the stability of the plasma is set to the constant F used in the above equation (3).

[0076] As the first bias frequency f B (1) and the second bias frequency f B (2) Values ​​predetermined according to the process formula can be recorded and read in step ST104, unrelated to the above. For example, plasma is generated in the plasma processing chamber 10 where a dummy wafer has been pre-loaded, and the dummy wafer is processed. At this time, several time-shifting modes of bias frequencies can be prepared and processed, and the bias frequency in the mode where reflection or reflectivity decreases during processing is determined as the first bias frequency f. B (1) and the second bias frequency fB (2).

[0077] Steps ST100 to ST110 constitute a feedback loop. Control is repeatedly performed in this loop such that the reflected wave power Pr(n) that might be generated corresponding to the bias signal supplied in the nth control cycle is less than the reflected wave power Pr(n-1) in the (n-1)th control cycle. That is, the nth reflected wave power Pr(n) is expected to be less than the (n-1)th reflected wave power Pr(n-1). In step ST108, if the reflected wave power generated corresponding to the bias signal supplied in the current (nth control cycle) control cycle is less than a threshold, it is determined that the reflected wave power is sufficiently small. This is achieved by using a stable bias frequency f that provides such a reflected wave power Pr. BC The bias signal can suppress the reflected wave power to a sufficiently small level. In addition, in this specification, the nth control cycle is sometimes referred to as the "current control cycle", the (n-1)th control cycle as the "previous control cycle", and the (n-2)th control cycle as the "previous control cycle".

[0078] More specifically, in step ST102, the bias frequency f is determined using the values ​​of the bias frequency and reflected wave power from the (n-1)th control cycle and the (n-2)th control cycle. B (n). Therefore, the nth bias frequency f can be determined in such a way that the power of the nth reflected wave Pr(n) is less than the power of the (n-1)th reflected wave Pr(n-1). B (n). The rationale for this will be explained together with the contributions of each term in equation (3) in step ST102.

[0079] f on the right side of equation (3) B (n-1) is subtracted from the second term on the right-hand side of equation (3) by Δf / ΔP×Pr(n-1)×F. That is, the nth bias frequency f B (n) is the bias frequency f obtained by the second term on the right side of equation (3) for the (n-1)th bias frequency. B It is calculated by correcting (n-1).

[0080] Here, the ratio Δf / ΔP, which is the difference in bias frequency Δf and the difference in reflected wave power ΔP, in the second term on the right side of equation (3), is explained. The sign of the ratio Δf / ΔP is relative to the bias frequency f in the nth control cycle. B The control direction (increasing or decreasing) contributes to (n). That is, Δf>0 means that in the (n-1)th control cycle, f... B (n-1) compared to f B Control was implemented by decreasing in a manner equivalent to (n-2). Furthermore, Δf < 0 means that in the (n-1)th control cycle, f... B(n-1) compared to f B Control was implemented by increasing (n-2). Furthermore, ΔP>0 means that Pr(n-1) decreased compared to Pr(n-2) in the (n-1)th control cycle. Conversely, ΔP≤0 means that Pr(n-1) increased or remained unchanged compared to Pr(n-2) in the (n-1)th control cycle. Here, as an example, we consider the case where Δf>0 and ΔP>0. Δf>0 and ΔP>0 means that by increasing f in the (n-1)th control cycle... B (n-1) compared to f B Control is implemented by decreasing Pr(n-1) in a manner that is equal to (n-2) decreases, while Pr(n-1) decreases compared to Pr(n-2). In this case, it is expected that by also decreasing f in the nth control cycle... B (n) compared to f B Controlled by decreasing (n-1), Pr(n) also decreases compared to Pr(n-1). When Δf>0 and ΔP>0, Δf / ΔP>0, and the sign of the second term on the right side of equation (3) is determined by Δf / ΔP. Therefore, the sign of the second term on the right side of equation (3) is determined to be negative (i.e., subtract the second term on the right side of equation (3) from the first term on the right side of equation (3)). When the sign of the second term on the right side of equation (3) is negative, f B (n) compared to f B (n-1) decreases. Similarly, when Δf<0 and ΔP>0, Δf / ΔP<0, and the sign of the second term on the right side of equation (3) is positive. When Δf>0 and ΔP<0, Δf / ΔP<0, and the sign of the second term on the right side of equation (3) is positive. When Δf<0 and ΔP<0, Δf / ΔP>0, and the sign of the second term on the right side of equation (3) is negative. As described above, the bias frequency f of the nth control cycle can be determined using the sign of Δf / ΔP. B (n) controls the direction (the direction of increase or decrease).

[0081] From this perspective, the sign of the ratio Δf / ΔP, which is the difference in bias frequency Δf and the difference in reflected wave power ΔP, can be constructed by referring only to Equation (3). That is, in Equation (3), instead of the ratio Δf / ΔP, using (Δf / ΔP) / |Δf / ΔP| as the sign of the ratio Δf / ΔP, the following Equation (3-1) can be derived.

[0082] f(n)=f(n-1)-(Δf / ΔP) / |Δf / ΔP|×|ΔP|×F...Equation (3-1)

[0083] Furthermore, in the second term on the right side of equation (3), the absolute value of the ratio Δf / ΔP, the value of Pr(n-1), and the constant F each contribute to the control quantity, which is given by their product. Specifically, the control quantity is calculated in such a way that the larger the value of Δf, the smaller the value of ΔP, and the larger the value of Pr(n-1), the larger the control quantity.

[0084] By determining the control direction and control quantity in the manner described above, the values ​​of the bias frequency and reflected wave power, which are the control results in the (n-1)th and (n-2)th control cycles, can be reflected in the nth bias frequency f determined in the nth control cycle. B (n)

[0085] Based on the above implementation method, the nth bias frequency f can be determined in such a way that the power Pr(n) of the nth reflected wave is less than a threshold. B (n), to obtain a stable bias frequency f BC By using a stable bias frequency f BC The bias signal can continue the process while suppressing the reflected wave power sufficiently.

[0086] Furthermore, in the above embodiment, the value of the reflected wave power is used to determine the nth bias frequency f. B (n), but not limited to this. The reflected wave power is a parameter that quantitatively represents the impedance matching state. Therefore, similarly to the reflected wave power, other required parameters regarding the impedance matching state obtained in the previous and the preceding control cycles can be used to determine the nth bias frequency f. B (n). Other parameters relating to the impedance matching state can be, for example, the ratio of reflected wave power to input bias power, i.e., reflectivity (reflected wave power / input bias power). Additionally, other parameters relating to the impedance matching state can be, for example, the voltage V, current I, and phase difference θ between the bias signal and the current I. Furthermore, the bias frequency f can also be changed. B (n) to bring the impedance value close to the specified value (50Ω in one example). This is also the case in the following implementation.

[0087] <Second Implementation Method>

[0088] The bias signal supply method MT20 of the second embodiment will be described. In this embodiment, a bias signal pulsed by ON / OFF control or HIGH / LOW control is supplied. At this time, the bias frequency is changed according to each control cycle to obtain the required bias frequency. In addition, the bias frequency control is performed according to the control cycle of each pulse cycle. Regarding the pulse, in the case of ON / OFF control, the period from ON (on) to OFF (off) of the bias signal is defined as one pulse, and the period from the start and end of one pulse to the start of the next pulse is defined as one pulse cycle. In the case of HIGH / LOW control, the period from when the bias signal is set to HIGH (high level) to when it is set to LOW (low level) is defined as one pulse, and the period from the start of one pulse to the start of the next pulse is defined as one pulse cycle. In this embodiment, specifically, the division of control by steps ST200 to ST220 described below is used as one pulse cycle. In addition, in this embodiment, specifically, the division of control by steps ST202 to ST210 described below is used as one control cycle. Furthermore, in this invention, the nth control cycle in the mth pulse is denoted as the (m, n)th control cycle, the nth control cycle in the (m-1)th pulse is denoted as the (m-1, n)th control cycle, the (n-1)th control cycle in the mth pulse is denoted as the (m, n-1)th control cycle, and the (n-1)th control cycle in the (m-1)th pulse is denoted as the (m-1, n-1)th control cycle, for distinction.

[0089] First, use Figure 7 The overall flow of the bias signal supply method MT20 in the second embodiment will be described. First, the initial value of the pulse period m is set to (m=3), and the m-th pulse begins (ST200). Next, the initial value of the control period n is set to (n=3), and the (m, n)-th control period in the m-th pulse begins (ST202). Then, the (m, n)-th bias frequency f is determined and recorded. B (m, n)(ST204). The (m, n)th bias frequency f B The method for determining (m, n) will be described later. Next, the determined (m, n)th bias frequency f is supplied. BThe bias signal (m, n) is used (ST206). Next, the power of the (m, n)th reflected wave Pr(m, n) reflected from the load is measured and recorded when this bias signal is supplied (ST208). Next, the value of the (m, n)th reflected wave power Pr(m, n) is compared with a threshold to determine the magnitude relationship (ST210). Here, the threshold can be a value predetermined according to the process formula and read in step ST210. In step ST210, if the value of the (m, n)th reflected wave power Pr(m, n) is less than the threshold, the bias frequency f of (m, n) is adjusted. B (m, n) is recorded as the stable bias frequency f. BC (ST212). Additionally, in step ST210, if the value of the (m, n)th reflected wave power Pr(m, n) is above a threshold, it is determined whether to continue the m-th pulse (ST214). The decision to continue the m-th pulse can be based on the pulse interval predetermined according to the process formula, determining whether the required time has elapsed since the pulse began. If the m-th pulse continues in step ST214, the (m, n)-th control cycle ends, n=n+1 is taken, and the next control cycle begins (ST216). In the (m, n+1)-th control cycle, steps ST202~ST214, executed in the (m, n)-th control cycle, are repeated. Then, for any natural number k, steps ST202~ST214 are repeated in the (m, n+k)-th control cycle. If the m-th pulse is not continued in step ST214, the m-th pulse ends (ST218). Next, it is determined whether to continue the process (ST220). If the process is not continued, the process ends. If the process continues, take (m=m+1) and begin the next pulse cycle (ST222). In the (m+1)th pulse, repeat steps ST200~ST220 as performed in the mth pulse. Thereafter, for any natural number j, repeat steps ST200~ST220 in the same way in the (m+j)th pulse.

[0090] Figure 8This is a graph summarizing the changes in the ON / OFF (HIGH / LOW) of the bias signal, the bias frequency, and the reflected wave power per unit time when the bias signal supply method MT20 of the second embodiment is executed. Steps ST200 to ST220 are repeatedly executed in each pulse cycle. In each pulse, the bias frequency is determined by referring to the reflected wave power in the same control cycle of the previous (m-1) pulse and the pulse two years before that (m-2) pulse. Therefore, the reflected wave power in the current control cycle of the current pulse (m-1) is smaller than the reflected wave power in the same control cycle of the previous and the pulse two years before that. It is expected that by repeatedly executing steps ST200 to ST220, the reflected wave power will be less than the threshold in all control cycles in a certain pulse cycle. The frequency control mode in this pulse cycle is called the stable mode. Details of the stable mode will be described later. In addition, in this specification, the m-th pulse is sometimes referred to as the "current pulse", the (m-1)-th pulse as the "previous pulse", and the (m-2)-th pulse as the "previous pulse".

[0091] Next, in the bias signal supply method MT20 of the second embodiment, the (m, n)th bias frequency f is determined. B The steps (ST204) for (m, n) are explained in detail. Figure 9 It means Figure 7 The middle determines the (m, n)th bias frequency f B A flowchart detailing the steps (m, n) is provided. First, the constant F (ST230) is determined. The constant F can be recorded as a value predetermined based on the process formulation and read in step ST230. Next, the (m-2, n)th bias frequency f is read. B (m-2, n), the (m-1, n)th bias frequency f B The power of the (m-1, n)th reflected wave is Pr(m-2, n), and the power of the (m-2, n)th reflected wave is Pr(m-2, n). Next, the change in bias frequency Δf is calculated by the following equation (4), the change in reflected wave power ΔP is calculated by the following equation (5), and the (m, n)th bias frequency f is determined and recorded by the following equation (6). B (m, n).

[0092] Δf=f B (m-2, n)-f B (m-1, n)···(4)

[0093] ΔP=Pr(m-2, n)-Pr(m-1, n)···(5)

[0094] f B (m, n)=f B (m-1, n)-Δf / ΔP×Pr(m-1, n)×F···(6)

[0095] Here, regarding the determination of the (m, n)th bias frequency f B Step (ST204) of (m, n) is performed at the (m-1, n)th bias frequency f. B (m-1, n) is recorded as the stable bias frequency f. BC In this case, the stable bias frequency f can be used regardless of the above description. BC As the (m, n)th bias frequency f B (m, n). At this point, the stable bias frequency f BC It can obtain different values ​​for each control cycle. The stable bias frequency f is recorded in all control cycles. BC In this case, it is possible to achieve such a stable bias frequency f BC The combination of these is recorded as a stable mode. After achieving the stable mode, the bias signal can be supplied using the stable mode during the pulse cycle. Therefore, for example, regarding... Figure 8 As explained, the bias signal can be supplied in a manner that ensures the reflected wave power is less than the threshold throughout the entire control cycle. Furthermore, when determining the stable mode, it is not necessary to limit it to the entire control cycle, but rather to record the stable bias frequency f within a required proportion of the control cycle. BC In this case, the stable bias frequency f BC The combination of these factors determines the stable mode.

[0096] After determining the stable mode, steps ST202 to ST212 can be executed every required time or every required number of pulses to confirm that the reflected wave power is less than a threshold. For example, the required time is 1 m / s to 10 m / s in the first confirmation, sub-seconds in the second confirmation, and several minutes in the third confirmation. The reflected wave power is confirmed in each of the first to third confirmations, and the bias frequency is adjusted accordingly.

[0097] Steps ST202 to ST212 constitute a feedback loop. Control is repeatedly performed in this loop such that the reflected wave power Pr(m, n) that might be generated corresponding to the bias signal supplied in the (m, n)th control cycle is less than the reflected wave power Pr(m-1, n) in the nth control cycle of the (m-1)th pulse. That is, the reflected wave power Pr(m, n) of the (m, n)th pulse is expected to be less than the reflected wave power Pr(m-1, n) of the (m-1, n)th pulse. In step ST210, if the reflected wave power generated corresponding to the current bias signal is less than a threshold, it is determined that the reflected wave power is sufficiently small. This is achieved by using a stable bias frequency f that provides such a reflected wave power Pr. BC The bias signal can suppress the reflected wave power to a sufficiently small level.

[0098] More specifically, in step ST204, the bias frequency f is determined using the values ​​of the bias frequency and reflected wave power of the (m-1, n)th control cycle and the (m-2, n)th control cycle. B (n). That is, referring to the bias frequency and reflected wave power values ​​of the same control cycle in the previous and the pulse cycle before that, the (m, n)th bias frequency f in the current pulse cycle is determined. B (m, n). Therefore, the nth bias frequency f can be determined in such a way that the power of the (m, n)th reflected wave Pr(m, n) is less than the power of the (m-1, n)th reflected wave Pr(m-1, n). B (m, n). The rationale is explained along with the contributions of each term in equation (6) in step ST204.

[0099] f of the first term on the right side of equation (6) B (m-1, n) is subtracted from the second term on the right-hand side of equation (6) by Δf / ΔP×Pr(m-1, n)×F. That is, the (m, n)th bias frequency f B (m, n) is the bias frequency f at the (m-1, n)th bias frequency obtained by the second term on the right side of equation (6). B It is calculated by correcting (m-1, n).

[0100] The ratio Δf / ΔP, which represents the difference in bias frequency Δf and the difference in reflected wave power ΔP, in the second term on the right-hand side of equation (6) is explained. The sign of the ratio Δf / ΔP corresponds to the bias frequency f in the (m, n)th control cycle. B The control direction at (m, n) contributes. That is, Δf > 0 means that in the (m-1, n)th control cycle, f contributes. B (m-1, n) compared to f BControl was implemented by decreasing in the manner of (m-2, n). Furthermore, Δf < 0 means that in the (m-1, n)th control cycle, f... B (m-1, n) compared to f B Control was implemented by increasing (m-2, n). Furthermore, ΔP>0 means that Pr(m-1, n) decreased compared to Pr(m-2, n) in the (m-1, n)-th control cycle. Conversely, ΔP≤0 means that Pr(m-1, n) increased or remained unchanged compared to Pr(m-2, n) in the (m-1, n)-th control cycle. Here, as an example, we consider the case where Δf>0 and ΔP>0. Δf>0 and ΔP>0 means that by increasing f in the (m-1, n)-th control cycle... B (m-1, n) compared to f B Control is implemented by decreasing (m-2, n), and Pr(m-1, n) decreases compared to Pr(m-2, n). In this case, it is expected that by also using f in the (m, n)th control cycle... B (m,n) compared to f B The control is implemented by decreasing (m-1, n), and Pr(m, n) also decreases compared to Pr(m-1, n). When Δf>0 and ΔP>0, Δf / ΔP>0, and the sign of the second term on the right side of equation (6) is determined by Δf / ΔP. Therefore, the sign of the second term on the right side of equation (6) is determined to be negative (i.e., subtracting the second term on the right side of equation (6) from the first term on the right side of equation (6)). When the sign of the second term on the right side of equation (6) is negative, f B (m, n) compared to f B (m-1, n) decreases. Similarly, when Δf<0 and ΔP>0, Δf / ΔP<0, and the sign of the second term on the right side of equation (6) is positive. When Δf>0 and ΔP<0, Δf / ΔP<0, and the sign of the second term on the right side of equation (6) is positive. When Δf<0 and ΔP<0, Δf / ΔP>0, and the sign of the second term on the right side of equation (6) is negative. In this way, the bias frequency f of the (m, n)th control cycle can be determined by the sign of Δf / ΔP. B (m, n) controls the direction.

[0101] Furthermore, in the second term on the right side of equation (6), the absolute value of the ratio Δf / ΔP, the value of Pr(m-1, n), and the constant F each contribute to the control quantity, which is given by their product. Specifically, the control quantity is calculated in such a way that the larger the value of Δf, the smaller the value of ΔP, and the larger the value of Pr(m-1, n), the larger the control quantity.

[0102] By determining the control direction and control quantity in the manner described above, the values ​​of the bias frequency and reflected wave power, which are the control results in the (m-1, n)th control cycle and the (m-2, n)th control cycle, can be reflected in the bias frequency f determined in the (m, n)th control cycle. B In (m, n).

[0103] Based on the above implementation method, the bias frequency f can be determined such that the power Pr(m, n) of the (m, n) reflected wave is less than a threshold. B (m, n). Furthermore, a stabilization mode can be determined such that the reflected wave power Pr(m, n) is less than a threshold during the control cycle at the required ratio. By using a bias signal with the stabilization mode applied, the process can continue while suppressing the reflected wave power sufficiently.

[0104] In addition, equations (4) to (6) refer to the previous and previous pulse periods, but are not limited to them. For example, the current bias frequency can be determined by referring to the (mh)th pulse and the (mh-1)th pulse, where h is the required integer greater than 2.

[0105] <Third Implementation Method>

[0106] use Figure 10 The bias signal supply method of the third embodiment will be described. In this embodiment, a bias signal that is pulsed by ON / OFF control or HIGH / LOW control is supplied. At this time, the bias frequency is varied according to each control cycle to obtain the required bias frequency. In addition, the bias frequency control is performed according to the control cycle of each pulse cycle.

[0107] The bias signal supply method of the third embodiment is characterized by continuously executing the first loop control LP1 and the second loop control LP2. Specifically, firstly, in the first loop control LP1, similarly to the bias signal supply method MT20 of the second embodiment, the bias frequency f in the current pulse period is determined by referring to the values ​​of the bias frequency and reflected wave power in the same control period in the previous and the pulse period before that. B (m, n). Then, in the second loop control LP2, similarly to the bias signal supply method MT10 of the first embodiment, the bias frequency f in the current control cycle is determined by referring to the values ​​of the bias frequency and reflected wave power of the previous and the preceding control cycles. B (m, n).

[0108] The overall flow of the bias signal supply method in the third embodiment will be described. First, the initial value of the pulse period m is set to (m=3), and the m-th pulse begins (ST300). Next, the initial value of the control period n is set to (n=3), and the (m, n)-th control period in the m-th pulse begins (ST302). Then, the (m, n)-th bias frequency f is determined and recorded. B (m,n)(ST304). Regarding the (m, n)th bias frequency f B The method for determining (m, n) can use the determination method defined for step ST204 in the bias signal supply method MT20 of the second embodiment. Next, the determined (m, n)th bias frequency f is supplied. B The bias signal (m, n) is used (ST306). Next, the power of the (m, n)th reflected wave Pr(m, n) reflected from the load is measured and recorded when the bias signal is supplied (ST308). Then, the value of the (m, n)th reflected wave power Pr(m, n) is compared with a reference value to determine the magnitude relationship (ST310). The reference value can be a value predetermined according to the process formula and read in step ST310. In step ST310, if the value of the (m, n)th reflected wave power Pr(m, n) is above the reference value, the current control cycle ends, n=n+1 is taken, and the next control cycle begins (ST312). After step ST312, in the next control cycle, the above steps ST302~ST310 executed in the (m, n)th control cycle are executed again. Thereafter, for any natural number k, the above steps ST302~ST310 are repeatedly executed in the (m, n+k)th control cycle. In step ST310, if the value of the (m, n)th reflected wave power Pr(m, n) is less than the reference value, the (m, n)th control cycle ends, n=n+1 is taken, and the next control cycle begins (ST314). Repeatedly executing steps ST302~ST310 is referred to as the first loop control LP1. The first loop control LP1 ends in step ST310 if the value of the (m, n)th reflected wave power Pr(m, n) is less than the reference value.

[0109] In the above description, the reference value can be determined in the same way as the threshold. That is, the reference value can use a past actual value regarding plasma stability for each process. In this case, the reference value has a required initial value, which can be reduced by a specified percentage each control cycle, or it can be varied every required time, or these can be arbitrarily selected and combined to vary it. By determining the reference value in this way, the impedance matching state can be improved as the control cycle or time elapses.

[0110] Furthermore, regarding the determination of the (m, n)th bias frequency f B Step (ST304) of (m, n) is performed at the (m-1, n)th bias frequency f B (m-1, n) is recorded as the stable bias frequency f. BC In this case, the stable bias frequency f can be used, regardless of the above description. BC As the (m, n)th bias frequency f B (m, n). Here, the stable bias frequency f BC It can obtain different values ​​for each control cycle. The stable bias frequency f is recorded in all control cycles. BC In this case, such a stable bias frequency f can be used. BC The combination of these parameters is recorded as a stable mode, which is used to supply the bias signal in subsequent pulse cycles. Alternatively, the stable bias frequency f can be recorded not only for the entire control cycle, but also for a required proportion of the control cycle. BC In this case, the stable bias frequency f BC The combination of these is used as a stable mode.

[0111] After the first cycle control LP1 ends, following step ST314, in the next control cycle, the (m,n)th bias frequency f is determined and recorded. B (m, n)(ST316). The (m, n)th bias frequency f in step ST316 B The method for determining (m, n) will be described later. Next, the determined (m, n)th bias frequency f is supplied. B The bias signal (m, n) is used (ST318). Next, the power of the (m, n)th reflected wave Pr(m, n) reflected from the load is measured and recorded when the bias signal is supplied (ST320). Next, the value of the (m, n)th reflected wave power Pr(m, n) is compared with a threshold to determine the magnitude relationship (ST322). The threshold can be a value predetermined according to the process formula and read in step ST310. In step ST322, if the value of the (m, n)th reflected wave power Pr(m, n) is above the threshold, the current control cycle ends, n=n+1 is taken, and the next control cycle begins. In the next control cycle, the above steps ST316~ST322 executed in the (m, n)th control cycle are executed again. Thereafter, for any natural number k, the above steps ST316~ST322 are repeatedly executed in the (m, n+k)th control cycle. In step ST322, if the value of the (m, n)th reflected wave power Pr(m, n) is less than the threshold, the (m, n)th bias frequency f is set to...B (m, n) is recorded as the stable bias frequency f. BC (ST324). Steps ST316 to ST322 are repeatedly executed and referred to as the second loop control LP2. The second loop control LP2 ends when the value of the (m, n)th reflected wave power Pr(m, n) in step ST322 is less than the threshold.

[0112] After the second cycle control LP2 ends, the stable bias frequency f continues to be supplied. BC The bias signal in the m-th pulse (ST326). Then, after the required time, the m-th pulse ends (ST328). Next, it is determined whether to continue the process (ST330). If the process does not continue, the process ends. If the process continues, (m=m+1) is taken, and the next pulse cycle begins (ST332). In the (m+1)-th pulse, the above steps ST300~ST330 executed in the m-th pulse are executed again. Thereafter, for any natural number j, the above steps ST300~ST330 are executed repeatedly in the (m+j)-th pulse.

[0113] Next, in the second loop control LP2 of the bias signal supply method of the third embodiment, the (m, n)th bias frequency f is determined. B The steps (ST316) of (m, n) are explained in detail. Figure 11 It means Figure 10 The middle determines the (m, n)th bias frequency f B A flowchart detailing step ST316 (m, n) is provided. First, the constant F (ST340) is determined. The constant F can be recorded as a value predetermined based on the process formulation and read in step ST340. Next, the (m, n-2)th bias frequency f is read. B (m, n-2), the (m, n-1)th bias frequency f B The power of the reflected wave is Pr(m, n-1), the power of the reflected wave is Pr(m, n-2), and the power of the reflected wave is Pr(m, n-1). Next, the change in bias frequency Δf is calculated by the following equation (7), the change in reflected wave power ΔP is calculated by the following equation (8), and the bias frequency f is determined and recorded by the following equation (9). B (m, n).

[0114] Δf=f B (m, n-2)-f B (m, n-1)···(7)

[0115] ΔP=Pr(m, n-2)-Pr(m, n-1)···(8)

[0116] f B (m, n)=f B (m, n-1)-Δf / ΔP×Pr(m, n-1)×F···(9)

[0117] The first loop control LP1 and the second loop control LP2 each constitute a feedback loop. Control is repeatedly performed in the first loop control LP1 such that the reflected wave power Pr(m, n) that might be generated corresponding to the bias signal supplied in the (m, n)th control cycle is less than the reflected wave power Pr(m-1, n) in the nth control cycle of the (m-1)th pulse. That is, the reflected wave power Pr(m, n) of the (m, n)th pulse is expected to be less than the reflected wave power Pr(m-1, n) of the (m-1, n)th pulse. In step ST310, if the reflected wave power generated corresponding to the current bias signal is less than a reference value, the first loop control LP1 ends, and the second loop control LP2 begins in the next control cycle.

[0118] Regarding the first loop control LP1, more specifically, in step ST304, the bias frequency f is determined by using the values ​​of the bias frequency and reflected wave power from the (m-1, n)th control cycle and the (m-2, n)th control cycle. B (n). That is, referring to the bias frequency and reflected wave power values ​​of the same control cycle in the previous and the pulse cycle before that, the (m, n)th bias frequency f in the current pulse cycle is determined. B (m, n). Therefore, the nth bias frequency f can be determined in such a way that the power of the (m, n)th reflected wave Pr(n) is less than the power of the (m-1, n)th reflected wave Pr(m-1, n). B (m, n). The reasoning is the same as that explained in step ST204 of the bias signal supply method MT20 of the second embodiment, so the repeated description is omitted.

[0119] In the second loop control LP2, control is repeatedly performed such that the reflected wave power Pr(m, n) that might be generated corresponding to the bias signal supplied in the (m, n)th control cycle is less than the reflected wave power Pr(m, n-1) that might be generated corresponding to the bias signal supplied in the (m, n-1)th control cycle. That is, the reflected wave power Pr(m, n) of the (m, n)th cycle is expected to be less than the reflected wave power Pr(m, n-1). In step ST322, if the reflected wave power generated corresponding to the current bias signal is less than a threshold, it is determined that the reflected wave power is sufficiently small. This is achieved by using a stable bias frequency f that gives such a reflected wave power Pr. BC The bias signal can suppress the reflected wave power to a sufficiently small level.

[0120] More specifically, in step ST316, the bias frequency f is determined using the values ​​of the bias frequency and reflected wave power of the (m-1, n)th control cycle and the (m-2, n)th control cycle. B (n). That is, referring to the bias frequency and reflected wave power values ​​of the same control cycle in the previous and the pulse cycle before that, the (m, n)th bias frequency f in the current pulse cycle is determined. B (m, n). Therefore, the nth bias frequency f can be determined in such a way that the power of the (m, n)th reflected wave Pr(n) is less than the power of the (m-1, n)th reflected wave Pr(m-1, n). B (m, n). The reasoning is the same as that explained in step ST102 of the bias signal supply method MT10 of the first embodiment, so the repeated description is omitted.

[0121] Based on the above implementation method, the bias frequency f can be determined such that the power Pr(m, n) of the (m, n) reflected wave is less than a threshold. B (m, n), to obtain a stable bias frequency f BC By using a stable bias frequency f BC The bias signal can suppress the reflected wave power to a sufficiently small level.

[0122] Furthermore, regarding the case where a pulsed source signal is supplied in step ST4 of the plasma processing method MT1, the following supplementary information is provided. When the ON / OFF or HIGH / LOW timing of the source signal is synchronized with the ON / OFF or HIGH / LOW timing of the bias signal supply method of the second or third embodiment, it is preferable to again obtain a stable bias frequency f for each power of the source signal supplied in step ST4. BCThis is because the reflected wave power depends on the source signal, specifically for the following reasons: When a source signal is supplied, the plasma density in the plasma processing space increases. As the plasma density increases, the plasma sheath becomes thinner. As the plasma sheath becomes thinner, the electrostatic capacitance, when the plasma sheath is considered a capacitor, increases. As the electrostatic capacitance increases, the impedance decreases, and consequently, the impedance of the plasma processing space decreases. Due to the decreased impedance, the amount of RF power reflected changes.

[0123] Next, a method for supplying a source signal to the upper electrode and / or lower electrode in plasma processing method MT1 (hereinafter referred to as the source signal supply method) will be described. The following source signal supply method MT40 can be performed as step ST4 in the plasma processing method MT1 described above. However, it is not limited thereto. For example, a gas corresponding to the process formulation can be supplied before the process begins, and then the following source signal supply method MT40 can be performed, thereby allowing the plasma ignition conditions in the process to be confirmed and recorded in advance. Afterwards, plasma processing method MT1 is performed, and in step ST4, the source signal is supplied using the previously recorded plasma ignition conditions as described above.

[0124] Furthermore, as explained below, regarding whether the plasma has ignited, the luminescence emitted by the plasma processing space can be detected by the OES, and the control unit will make a judgment based on the obtained information. Alternatively, the reflected wave power can be measured, and the control unit will determine whether the plasma has ignited based on the obtained information.

[0125] <Fourth Implementation Method>

[0126] Figure 12 This is a flowchart illustrating the outline of the source signal supply method MT40 according to the fourth embodiment. First, the overall flow of the source signal supply method will be explained. First, the source frequency f is executed at the initial matched unit position. SThe scan (ST400) is performed. Details of the initial matcher position and scan will be described later. Next, it is determined whether the resulting plasma ignites (ST402). If plasma ignition is not confirmed in step ST402, bias signal control (ST410) is then executed to determine whether the resulting plasma ignites (ST412). Details of bias signal control will be described later. If plasma ignition is not confirmed in step ST412, source signal control (ST414) is then executed to determine whether the resulting plasma ignites (ST416). Details of source signal control will be described later. If plasma ignition is not confirmed in step ST416, matcher position control (ST418) is then executed to determine whether the resulting plasma ignites (ST420). Details of matcher position control will be described later. If plasma ignition is not confirmed in step ST420, the stable frequency band is recalculated, and the steps after step ST400 are executed again using the recalculated stable frequency band. If plasma ignition is confirmed in steps ST402, ST412, ST416, and ST420, record the conditions at the time of ignition and continue the process (ST424). Additionally, the conditions at the time of ignition include the source frequency f at the moment ignition occurred during the scan. S Conditions such as bias signal, source signal, and matcheder position.

[0127] Next, use Figure 13 The method for determining the initial matcher position in step ST400 is explained. Figure 13 This is a flowchart outlining a method for determining the initial matched unit position before executing the source signal supply method or before performing a scan in step ST400. First, a gas (ST430) corresponding to the process formulation is supplied to the plasma processing space at an arbitrary source frequency f. S A scan is performed (ST432). During the scan, automatic matching position control is implemented to match the impedance of the RF power supply to the plasma processing space (ST434). As a result of the scan, the matching position at plasma ignition is recorded as the ignition matching position, and the matching position at plasma stabilization is recorded as the stable matching position (ST434). In one embodiment, the stable matching position is used as the initial matching position. Alternatively, in another embodiment, the initial matching position is predetermined as the position between the ignition matching position and the stable matching position, which allows plasma ignition to be achieved by executing bias signal control ST410 or source signal control ST414. Additionally, in one embodiment, the source frequency f at plasma ignition can be... S Recorded as stable frequency f SC and with a stable source frequency f SCThe upper and lower frequency limits are determined by a certain method, and the frequency band is defined as a stable frequency band for use in the following steps.

[0128] The following uses Figure 14 The source frequency sweep at the initial matched unit position is explained. Figure 14 It means in Figure 13 The flowchart below outlines the source frequency scan performed at the stable matched position in step ST400. First, the pre-determined and recorded initial matched position (ST438) is read. Next, at the read initial matched position, the source frequency f is adjusted by changing the frequency value. S Change (ST440). The scan is performed in any frequency band. In one embodiment, the scan can be performed in a stable frequency band. In this case, as a source frequency scan, the source frequency f can be reduced from the upper limit frequency to the lower limit frequency in step ST440, for example. S Change. Alternatively, for example, the source frequency f can be increased from the lower limit frequency to the upper limit frequency in step ST440. S Changes. Alternatively, for example, in step ST440, the source frequency f during plasma ignition can be changed. S Used as the initial source frequency, the distance f from that source frequency S The furthest value is used as the final source frequency, causing the frequency value to change from the initial source frequency to the final source frequency. After plasma ignition, the matched pair position can be moved from the initial matched pair position to the stable matched pair position.

[0129] Next, use Figures 15-19 The bias signal control ST410 in the source signal supply method MT40 of the fourth embodiment will be described.

[0130] Figure 15 This is a flowchart outlining the bias signal control step ST410 of one embodiment. In the bias signal control of this embodiment, a stable bias frequency f corresponding to any process formulation is used. BC Supply bias signal (ST450). Stabilize bias frequency f BC The bias frequency can be a bias signal supplied in a manner that can stably maintain plasma within the process formulation. Furthermore, the bias signal can be pulsed via ON / OFF control or HIGH / LOW control. Then, while supplying the bias signal, the source frequency f is executed at the initial matched unit position. S Scan (ST452). The scan in step ST452 may be a source frequency scan at the initial matched position defined in step ST400.

[0131] Figure 16 It means that it has been executed. Figure 15The example shows the curves of source frequency, bias signal, supply wave power, reflected wave power, and luminous intensity in the case of bias signal control step ST410. Figure 16 As shown, by supplying a pulse bias signal while performing source frequency scanning, the reflected wave power decreases or the luminous intensity in the plasma processing space increases at a certain moment, causing the plasma to ignite.

[0132] Figure 17 This is a flowchart outlining the bias signal control step ST410 of another embodiment. In this other embodiment of bias signal control, the bias period is set to be the same as the source frequency f. S The control cycle is synchronized. Furthermore, the bias cycle is synchronized with... Figure 17 One ON / OFF cycle of the bias rectangular wave shown is one period. In the example shown, the bias signal is a rectangular wave, but the bias signal can also be a sine wave. The bias period p is set to (p=1), and the control period q is set to (q=1), starting the p-th bias pulse and the q-th control cycle (ST460). Then, at the q-th source frequency f... S (q) Supply source signal (ST462). Next, determine whether the plasma is ignited (ST464). If the plasma is ignited in step ST464, end the bias signal control. If the plasma is not ignited in step ST464, determine whether the control period q is the maximum value Q (ST466). If the control period q is not the maximum value Q in step ST466, set the bias pulse period p to (p=p+1), set the control period q to (q=q+1), and execute the steps after step ST460 again (ST468). If the control period q is the maximum value Q in step ST466, end the bias signal control. Furthermore, the control period q being the maximum value Q indicates that the arbitrarily determined control period q has reached the Qth control period, which is the final control period. For example, when the source frequency f is... S When the upper limit frequency of the stable frequency band changes to the lower limit frequency, the first source frequency f can be made... S (1) is the upper limit frequency, such that the Q-th source frequency f S (Q) is the lower limit frequency, and the control cycle is formed by decreasing the frequency in stages according to each control cycle. Alternatively, the first source frequency f can be... S (1) is the lower limit frequency, such that the Q-th source frequency f S (Q) is the upper limit frequency, and the control cycle is formed by increasing the frequency in stages according to each control cycle. Alternatively, the source frequency f during plasma ignition can also be used. S Used as the first source frequency f S (1) The distance from the source frequency f S The furthest value is used as the Q-th source frequency fS (Q) causes the frequency to change from the initial source frequency to the final source frequency f in each control cycle. S (Q) constitutes the control cycle.

[0133] Figure 18 It means that it has been executed. Figure 17 The example shows the curves of source frequency, bias signal, supply wave power, reflected wave power, and luminous intensity in the case of bias signal control step ST410. Figure 18 As shown, by synchronizing the bias period with the control period of the source frequency while performing control, the reflected wave power decreases or the luminous intensity in the plasma processing space increases during a certain bias period and control period, and the plasma ignites.

[0134] Figure 19 This is a flowchart outlining the bias signal control step ST410 of another embodiment. In this bias signal control of another embodiment, steps ST480 to ST494, which are the same as those in the bias signal supply method MT1 described above, are performed. First, a source frequency scan at the initial matched unit position is started (ST470). Furthermore, the source frequency scan from the start of the scan in step ST470 to the end of the scan in step ST496 described later can be a source frequency scan at the initial matched unit position defined in step ST400. In other words, the steps ST480 to ST494 described below are performed during the execution of the source frequency scan at the initial matched unit position defined in step ST400. Next, the initial value of the control period n is set to (n=3), and the nth control period begins (ST480). Next, the nth bias frequency f is determined and recorded. B (n)(ST482). The nth bias frequency f B The method for determining (n) can be the method defined in step ST102 of the bias signal supply method MT1 described above. Next, the determined nth bias frequency f is supplied. BThe bias signal (n) is then applied (ST484). Next, the power of the nth reflected wave Pr(n) reflected from the load is measured and recorded with this bias signal applied (ST486). Then, the value of the nth reflected wave power Pr(n) is compared with a threshold value to determine the magnitude relationship (ST488). The threshold value can be a value predetermined according to the process formula and read in step ST488. In step ST488, if the value of the nth reflected wave power Pr(n) is above the threshold value, the nth control cycle ends, and (n=n+1) is set, and the next control cycle begins (ST490). In the (n+1)th control cycle, steps ST480 to ST488, which were performed in the nth control cycle, are executed again. Thereafter, for any natural number k, steps ST480 to ST488 are repeatedly executed in the (n+k)th control cycle. In step ST488, if the value of the nth reflected wave power Pr(n) is less than a threshold, the nth bias frequency f is adjusted. B (n) is recorded as the stable bias frequency f BC (ST492). Next, a stable bias frequency f was supplied. BC The bias signal is set (ST494). Then, the source frequency scan at the initial matched unit position ends (ST496). Furthermore, in step ST488 above, the value of the nth reflected wave power Pr(n) is compared with a threshold, but this is not a limitation. Instead of this comparison, for example, it can be determined whether plasma ignition has occurred. If plasma ignition is determined to have occurred in step ST488 and no plasma ignition has occurred, the nth control cycle ends, n=n+1 is taken, and the next control cycle begins (ST490). Alternatively, if plasma ignition is determined to have occurred in step ST488, the nth bias frequency f is set... B (n) is recorded as the stable bias frequency f BC (ST492).

[0135] Next, use Figure 20 The source signal control ST414 in the source signal supply method MT40 of the fourth embodiment will be described.

[0136] Figure 20 This is a flowchart illustrating an overview of source signal control ST414 in one embodiment. In this embodiment of source signal control, scanning is performed while changing the source power at each control cycle. First, the control cycle t is set to (t=1), and the t-th control cycle (ST500) begins. Next, the power of the source signal is set to the t-th source power P. S (t)(ST502). Next, the t-th source power P, which was set, was applied. SThe source signal (t) is used to perform a source frequency scan at the initial matched position (ST504). The scan in step ST504 can be a source frequency scan at the initial matched position defined in step ST400. Next, it is determined whether the plasma is ignited (ST506). If the plasma is ignited in step ST506, the source signal control ends. If the plasma is not ignited in step ST506, it is determined whether the control period t is the maximum value T (ST508). If the control period t is not the maximum value T in step ST508, the control period t is set to (t=t+1), and the steps after step ST500 are executed again (ST510). If the control period t is the maximum value T in step ST508, the source signal control ends. Furthermore, the control period t being the maximum value T indicates that the arbitrarily determined control period t has reached the Tth control period, which is the final control period. For example, the arbitrarily determined minimum power can be used as the first source power P. S (1) Use the arbitrarily determined maximum power as the T-th source power P S (T) is used to form a control cycle by increasing the source power in stages according to each control cycle.

[0137] Next, use Figure 21 The matching unit position control ST418 in the source signal supply method MT40 of the fourth embodiment will be described.

[0138] Figure 21 This is a flowchart illustrating an overview of a matcher position control ST418 according to one embodiment. In this embodiment of matcher position control, scanning is performed while changing the matcher position each control cycle. First, the control cycle d is set to (d=1), and the d-th control cycle begins (ST520). The matcher position before the start of this control is the initial matcher position. Next, the matcher position is set to the d-th matcher position P. S (d)(ST522). Next, at the set d-th matcher position P S (d) Execution source frequency f SScan (ST524). Next, determine if the plasma ignites (ST526). If the plasma ignites in step ST526, end the matcher position control. If the plasma does not ignite in step ST526, determine if the control period d is the maximum value D (ST528). If the control period d is not the maximum value D in step ST528, set the control period d to (d=d+1), and execute the steps after step ST520 again (ST530). If the control period d is the maximum value D in step ST528, end the matcher position control. Furthermore, a control period d being the maximum value D indicates that the arbitrarily determined control period d has reached the Dth control period, which is the final control period. For example, the initial matcher position can be used as the first matcher position P. S (1) Use the arbitrarily determined final position as the D-th matcher position P. S (D) The control cycle is formed by moving the matcher in stages according to each control cycle.

[0139] Next, the significance of the source signal supply method MT40 in the fourth embodiment, as described above, will be explained. In the source signal supply method MT40 of the fourth embodiment, since the source frequency is scanned at the initial matching position near the ignition matching position, plasma ignition can be achieved without a matching position change that takes only a few seconds. This shortens the time required for plasma ignition and suppresses damage to the RF power supply caused by the sum of reflected wave power generated during this period.

[0140] Furthermore, when performing source frequency scanning at an initial matcher position different from the ignition matcher position, impedance matching is difficult to achieve, resulting in difficulty in plasma ignition. Therefore, the source signal supply method MT40 in the fourth embodiment includes a bias signal control ST410, a source signal control ST414, and a matcher position control ST418.

[0141] Regarding the bias signal control ST410, the control of the bias signal, including the change of the bias frequency, can be changed in microseconds. In one embodiment of the bias signal control ST410, a stable bias frequency f under plasma ignition conditions is supplied. BC Therefore, when performing a source frequency scan at the initial matcheder position, the plasma is more easily ignited. Additionally, in another embodiment of the bias signal control ST410, the bias period of the bias signal is made to be synchronized with the source frequency f. SThe control cycle is synchronized, making plasma ignition easier and facilitating the acquisition of plasma ignition conditions. Furthermore, in another embodiment of the bias signal control ST410, since steps ST480 to ST494, which are the same as those in the bias signal supply method MT1, are performed, the bias frequency can be determined by reducing reflected wave power during the scanning of the source frequency at the initial matched position. This suppresses damage to the RF power supply caused by the sum of reflected wave power generated during the scan.

[0142] Regarding the source signal control ST414, the control of source signals, including changes in source power, can be changed in microseconds.

[0143] Therefore, the source signal supply method MT40 of the fourth embodiment can perform source frequency scanning ST400, bias signal control ST410, and source signal control ST414 at the initial matched position in microseconds. Thus, if plasma ignition is achieved by source signal control ST414, the time required for plasma ignition can be shortened compared to existing methods.

[0144] It should be considered that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The above embodiments may be omitted, substituted, or modified in various ways without departing from the claimed technical solution and its spirit.

[0145] Furthermore, the following structural examples can also be derived from the present invention.

[0146] (a) A plasma processing method for plasma processing a substrate, comprising: setting a matcher position to an initial matcher position; performing a source signal scan at the initial matcher position; performing the scan while supplying a bias signal in the absence of plasma ignition; performing the scan by increasing the source power in the absence of plasma ignition; and performing the scan while changing the position of the matcher in the absence of plasma ignition.

[0147] (b) The plasma processing method according to (a) above, wherein the initial matcher position is a stable matcher position.

[0148] (c) The plasma processing method according to (a) and (b) above, wherein the bias signal is supplied while the bias frequency is varied.

[0149] (d) A plasma processing method according to any one of (a) to (c) above, wherein the method comprises: acquiring the generated reflected wave power for each control cycle of the bias signal when the bias signal is supplied, and determining the frequency f(n) of the bias signal in the nth control cycle by the following equation (10).

[0150] f(n)=f(n-1)-Δf / ΔP×Pr(n-1)×F…Equation (10),

[0151] Specifically, the frequency of the (n-2)th control cycle is set to f(n-2), the frequency of the (n-1)th control cycle is set to f(n-1), the reflected wave power of the (n-2)th control cycle is set to Pr(n-2), and the reflected wave power of the (n-1)th control cycle is set to Pr(n-1).

[0152] Δf = f(n-2) - f(n-1),

[0153] ΔP = Pr(n-2) - Pr(n-1),

[0154] Where n is an integer greater than or equal to 3, and F is a constant.

[0155] (e) A plasma processing method for plasma processing a substrate, comprising: acquiring, at each control cycle of a bias signal, the reflected wave power of the bias signal generated when the bias signal is supplied to an electrode disposed on a substrate support; and determining the frequency f(n) of the bias signal in the nth control cycle by the following equation (11).

[0156] f(n)=f(n-1)-(Δf / ΔP) / |Δf / ΔP|×|ΔP|×F...Equation (11),

[0157] Specifically, the frequency of the (n-2)th control cycle is set to f(n-2), the frequency of the (n-1)th control cycle is set to f(n-1), the reflected wave power of the (n-2)th control cycle is set to Pr(n-2), and the reflected wave power of the (n-1)th control cycle is set to Pr(n-1).

[0158] Δf = f(n-2) - f(n-1),

[0159] ΔP = Pr(n-2) - Pr(n-1),

[0160] Where n is an integer greater than or equal to 3, and F is a constant.

[0161] Explanation of reference numerals in the attached figures

[0162] 1. Plasma processing device

[0163] 2 Control Department

[0164] 11. Substrate support

[0165] 31 RF Power Supply

[0166] 33. Reflected wave detector

[0167] W substrate

Claims

1. A plasma processing method for plasma processing a substrate, comprising: For each control cycle of the bias signal, acquire parameters regarding the impedance matching state when the bias signal is supplied to the electrode disposed on the substrate support; and The frequency f(n) of the bias signal in the nth control cycle is determined by the following equation (1). f(n)=f(n-1)-Δf / ΔP×Pr(n-1)×F···(1), Specifically, the frequency of the (n-2)th control cycle is set to f(n-2), the frequency of the (n-1)th control cycle is set to f(n-1), the parameter of the (n-2)th control cycle is set to Pr(n-2), and the parameter of the (n-1)th control cycle is set to Pr(n-1). Δf = f(n-2) - f(n-1), ΔP = Pr(n-2) - Pr(n-1), Where n is an integer greater than or equal to 3, and F is a constant.

2. The plasma treatment method as described in claim 1, wherein, The parameter is the reflected wave power of the bias signal generated when the bias signal is supplied to the electrode disposed on the substrate support.

3. The plasma treatment method as described in claim 2, wherein, include: If the reflected wave power Pr(n) in the nth control cycle is above the threshold, the nth control cycle ends and the next control cycle begins, and the frequency f(n) of the bias signal is determined again by equation (1). and If the reflected wave power Pr(n) in the nth control cycle is less than the threshold, the frequency f(n) of the bias signal in the nth control cycle is recorded as the stable frequency.

4. A plasma treatment method for treating a substrate with plasma, comprising: For each control cycle of the pulsed bias signal, parameters regarding the impedance matching state when the bias signal is supplied to the electrodes disposed on the substrate support are obtained; and The frequency f(m, n) of the bias signal in the nth control cycle of the m-th pulse is determined by the following equation (2). f(m, n)=f(mh, n)-Δf / ΔP×Pr(mh, n)×F···(2), Specifically, the frequency of the nth control cycle of the (mh-1)th pulse is set to f(mh-1, n), the frequency of the nth control cycle of the (mh)th pulse is set to f(mh, n), the parameter of the nth control cycle of the (mh-1)th pulse is set to Pr(mh-1, n), and the parameter of the nth control cycle of the (mh)th pulse is set to Pr(mh, n). Δf = f(mh-1, n) - f(mh, n), ΔP = Pr(mh-1, n) - Pr(mh, n), Where h is an integer greater than or equal to 1, m and n are integers greater than or equal to 3, and F is a constant.

5. The plasma treatment method as described in claim 4, wherein, The parameter is the reflected wave power of the bias signal generated when the bias signal is supplied to the electrode disposed on the substrate support.

6. The plasma processing method as described in claim 5, wherein, include: If the reflected wave power Pr(m, n) in the (m, n)th control cycle is above the threshold, the (m, n)th control cycle ends and the next control cycle begins, and the frequency f(m, n) of the bias signal is determined again by equation (2); and If the reflected wave power Pr(m, n) in the (m, n)th control cycle is less than the threshold, the frequency f(m, n) of the bias signal in the (m, n)th control cycle is recorded as the stable frequency.

7. A plasma treatment method for plasma treating a substrate, comprising: For each control cycle of the pulsed bias signal, parameters regarding the impedance matching state when the bias signal is supplied to the electrodes disposed on the substrate support are obtained; In the first loop control, the frequency f(m, n) of the bias signal in the (m, n)th control cycle is determined by the following equation (3). If the parameter Pr(m, n) in the nth control cycle of the (m, n)th pulse is above the reference value, the nth control cycle ends and the next control cycle begins. The frequency f(m, n) of the bias signal is again determined by equation (3). If the parameter Pr(m, n) in the nth control cycle of the (m, n)th pulse is less than the reference value or n reaches the specified number of times, the first loop control ends and the second loop control begins. In the second loop control, the frequency f(m, n) of the bias signal is determined by the following equation (4). If the parameter Pr(m, n) in the (m, n)-th control cycle is above the threshold, the n-th control cycle ends and the next control cycle begins. The frequency f(m, n) of the bias signal is determined again by equation (4). If the parameter Pr(m, n) in the (m, n)-th control cycle is less than the threshold or after n reaches a specified number of times, the frequency f(m, n) of the bias signal in the (m, n)-th control cycle is recorded as the stable frequency. f(m, n)=f(m-1, n)-Δf1 / ΔP1×Pr(m-1, n)×F···(3), f(m, n)=f(m, n-1)-Δf2 / ΔP2×Pr(m, n-1)×F···(4), Specifically, the frequency of the nth control cycle of the (m-2)th pulse is set to f(m-2, n), the frequency of the nth control cycle of the (m-1)th pulse is set to f(m-1, n), the parameter of the nth control cycle of the (m-2)th pulse is set to Pr(m-2, n), the parameter of the nth control cycle of the (m-1)th pulse is set to Pr(m-1, n), the frequency of the (n-2)th control cycle of the mth pulse is set to f(m, n-2), the frequency of the (n-1)th control cycle of the mth pulse is set to f(m, n-1), the parameter of the (n-2)th control cycle of the mth pulse is set to Pr(m, n-2), and the parameter of the (n-1)th control cycle of the mth pulse is set to Pr(m, n-1). Δf1=f(m-2, n)-f(m-1, n), ΔP1=Pr(m-2, n)-Pr(m-1, n), Δf2=f(m, n-2)-f(m, n-1), ΔP2=Pr(m, n-2)-Pr(m, n-1), Where m and n are integers greater than or equal to 3, and F is a constant.

8. The plasma processing method as described in claim 7, wherein, The parameter is the reflected wave power of the bias signal generated when the bias signal is supplied to the electrode disposed on the substrate support.

9. The plasma processing method according to any one of claims 1 to 8, wherein, include: Set the matcher's position to the initial matcher position; A scan of the source signal is performed at the initial matcher position; The scan is performed while the bias signal is supplied, even when the plasma is not ignited. The scan is performed by increasing the source power; and The scan is performed while the position of the matcher is changed without plasma ignition.

10. The plasma processing method as described in claim 9, wherein, When supplying the bias signal, the frequency of the bias signal is varied during the supply process.

11. The plasma processing method as described in claim 8, wherein, include: When the bias signal is supplied, the power of the generated reflected wave is acquired according to each control cycle of the bias signal; and The frequency f(n) of the bias signal in the nth control cycle is determined by the following equation (5). f(n)=f(n-1)-Δf / ΔP×Pr(n-1)×F···(5), Specifically, the frequency of the (n-2)th control cycle is set to f(n-2), the frequency of the (n-1)th control cycle is set to f(n-1), the reflected wave power of the (n-2)th control cycle is set to Pr(n-2), and the reflected wave power of the (n-1)th control cycle is set to Pr(n-1). Δf = f(n-2) - f(n-1), ΔP = Pr(n-2) - Pr(n-1), Where n is an integer greater than or equal to 3, and F is a constant.

12. A plasma processing apparatus for performing plasma processing on a substrate, comprising: Substrate support portion; An RF power supply that can supply a bias signal to electrodes disposed on the substrate support and can be controlled to change the frequency of the bias signal; A reflected wave detector capable of acquiring the power of the reflected wave generated when the bias signal is supplied to the electrodes; and Control Department The control unit is capable of performing: The reflected wave power of the bias signal generated when the bias signal is supplied to the electrode disposed on the substrate support is acquired in each control cycle of the bias signal. and The frequency f(n) of the bias signal in the nth control cycle is determined by the following equation (6). f(n)=f(n-1)-Δf / ΔP×Pr(n-1)×F···(6), Specifically, the frequency of the (n-2)th control cycle is set to f(n-2), the frequency of the (n-1)th control cycle is set to f(n-1), the reflected wave power of the (n-2)th control cycle is set to Pr(n-2), and the reflected wave power of the (n-1)th control cycle is set to Pr(n-1). Δf = f(n-2) - f(n-1), ΔP = Pr(n-2) - Pr(n-1), Where n is an integer greater than or equal to 3, and F is a constant.

Images