Plasma processing device, power supply system, and frequency control method

Abstract

To provide a technique for reducing a degree of reflection of source high frequency power.SOLUTION: In a plasma processing device, a radio frequency power supply changes a source frequency of source radio frequency power at a plurality of first time points within a waveform cycle of an electrical bias, and specifies a first time change pattern of the source frequency that most suppresses a degree of reflection of the source radio frequency power while interpolating the source frequency in each of a plurality of first divided periods within the waveform cycle divided at the plurality of first time points. The radio frequency power supply changes the source frequency at the plurality of second time points in the waveform cycle from the first time pattern or a derivative pattern thereof, and specifies a second time change pattern of the source frequency in the waveform cycle that most suppresses a degree of reflection of the source radio frequency power while interpolating the source frequency in each of the plurality of second divided periods in the waveform cycle at the plurality of second time points.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A plasma processing apparatus is used in plasma processing of a substrate. The plasma processing apparatus generates plasma from a gas in a chamber by supplying a source high frequency power. The plasma processing apparatus uses a bias high frequency power to attract ions from the plasma generated in the chamber to the substrate. Patent Document 1 listed below discloses a plasma processing apparatus that modulates the power level and frequency of the bias high frequency power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-246091 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for reducing the degree of reflection of source RF power. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a radio frequency power source, and a bias power source. The substrate support is disposed within the chamber. The radio frequency power source is configured to supply a source radio frequency power to generate plasma from a gas within the chamber. The bias power source is configured to supply an electrical bias having a waveform period to the substrate support. The radio frequency power source is configured to identify a first time-varying pattern of a source frequency in the waveform period that best suppresses the degree of reflection of the source radio frequency power. The radio frequency power source changes the source frequency of the source radio frequency power at each of a plurality of first time points within the waveform period, and identifies the first time-varying pattern using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first division periods. The plurality of first division periods are divided by the plurality of first time points. The radio frequency power source is configured to identify a second time-varying pattern of the source frequency in the waveform period that best suppresses the degree of reflection of the source radio frequency power. The high frequency power source changes the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period from the first time-varying pattern or a time-varying pattern of the source frequency created from the first time-varying pattern, and identifies the second time-varying pattern using the source frequency at each of the plurality of second time points and the interpolated source frequency within each of the plurality of second divided periods. The plurality of second divided periods are divided by the plurality of second time points. The number of the plurality of second divided periods is greater than the number of the plurality of first divided periods. [Effects of the Invention]

[0006] According to one exemplary embodiment, it is possible to reduce the degree of reflection of source RF power. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. [Figure 3] FIG. 1 is a diagram illustrating an example of the configuration of a power supply system in a plasma processing apparatus according to an exemplary embodiment. [Figure 4] Each of FIGS. 4(a) and 4(b) is a diagram showing an example of the waveform of the electrical bias. [Figure 5] 10A and 10B are diagrams for explaining an example of optimization processing of a time change pattern of a source frequency. [Figure 6] 10A and 10B are diagrams for explaining an example of optimization processing of a time change pattern of a source frequency. [Figure 7] 10A and 10B are diagrams for explaining an example of optimization processing of a time change pattern of a source frequency. [Figure 8] 10A and 10B are diagrams for explaining an example of optimization processing of a time change pattern of a source frequency. [Figure 9] Each of (a) of FIG. 9 and (b) of FIG. 9 is a timing chart showing an example of the source high frequency power and the electrical bias. [Figure 10] Each of (a) and (b) of FIG. 10 is a timing chart showing an example of the source high frequency power and the electrical bias. [Figure 11] Each of (a) to (c) of FIG. 11 is a timing chart of an example of the electrical bias. [Figure 12] 1 is a flow diagram of a frequency control method according to one exemplary embodiment. [Figure 13] 1 is a flow chart illustrating an example of a step STA of a frequency control method according to one exemplary embodiment. [Figure 14] 1 is a flow chart illustrating an example of a step STA of a frequency control method according to one exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] FIG. 1 is a diagram illustrating an exemplary configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like.

[0011] The controller 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The controller 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the controller 2 may be included in the plasma processing apparatus 1. The controller 2 may include a processor 2a1, a storage unit 2a2, and a communication interface 2a3. The controller 2 may be implemented by, for example, a computer 2a. The processor 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be pre-stored in the storage unit 2a2 or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processor 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processor 2a1 may be a programmable logic device such as a CPU (Central Processing Unit) or an FPGA (Field-Programmable Gate Array). The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0012] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0013] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The substrate support 11 is electrically insulated from the housing of the plasma processing chamber 10.

[0014] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0015] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member.

[0016] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0017] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0018] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0019] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0020] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0021] Hereinafter, reference will be made to FIG. 3 together with FIG. 2. FIG. 3 is a diagram showing an example of the configuration of a power supply system in a plasma processing apparatus according to an exemplary embodiment. The power supply system 30 includes a high frequency power supply 31 and a bias power supply 32. The high frequency power supply 31 constitutes the plasma generating unit 12 of the embodiment. The high frequency power supply 31 is configured to generate a source high frequency power HF. The source high frequency power HF has a source frequency f S That is, the source high frequency power HF has a frequency equal to the source frequency f S It has a sinusoidal waveform with a source frequency f S can be a frequency in the range of 10 MHz to 150 MHz.

[0022] The high frequency power supply 31 is electrically connected to the high frequency electrode via a matching box 33 and is configured to supply source high frequency power HF to the high frequency electrode. The high frequency electrode may be provided within the substrate support 11. The high frequency electrode may be at least one electrode provided within the conductive member or ceramic member 1111a of the base 1110. Alternatively, the high frequency electrode may be an upper electrode. When the source high frequency power HF is supplied to the high frequency electrode, plasma is generated from the gas in the chamber 10.

[0023] The matching circuit 33 has a variable impedance. The variable impedance of the matching circuit 33 is set to reduce reflection of the source high frequency power HF from the load. The matching circuit 33 can be controlled by the control unit 2, for example.

[0024] In one embodiment, the high frequency power supply 31 may include a signal generator 31g, a D / A converter 31c, and an amplifier 31a. The signal generator 31g generates a source frequency f SThe signal generator 31g may be configured as a single programmable device 30p together with the signal generator 32g (described later), or may be configured as a programmable device separate from the signal generator 32g.

[0025] The output of the signal generator 31g is connected to the input of the D / A converter 31c. The D / A converter 31c converts the high frequency signal from the signal generator 31g into an analog signal. The output of the D / A converter 31c is connected to the input of the amplifier 31a. The amplifier 31a amplifies the analog signal from the D / A converter 31c to generate the source high frequency power HF. The gain of the amplifier 31a is specified to the high frequency power supply 31 by the control unit 2. Note that the high frequency power supply 31 does not need to include the D / A converter 31c. In this case, the output of the signal generator 31g is connected to the input of the amplifier 31a, and the amplifier 31a amplifies the high frequency signal from the signal generator 31g to generate the source high frequency power HF.

[0026] The bias power supply 32 is electrically coupled to the substrate support 11. The bias power supply 32 is electrically connected to a bias electrode in the substrate support 11 and is configured to supply an electric bias EB to the bias electrode. The bias electrode may be at least one electrode provided in the conductive member or ceramic member 1111a of the base 1110. The bias electrode may be common to the radio frequency electrode. When the electric bias EB is supplied to the bias electrode, ions from the plasma are attracted to the substrate W.

[0027] Hereinafter, reference will be made to FIGS. 4(a) and 4(b) along with FIGS. 2 and 3. Each of FIGS. 4(a) and 4(b) shows an example of an electric bias waveform. The bias power supply 32 is configured to periodically apply an electric bias EB having a waveform period CY to the bias electrode. That is, the electric bias EB is applied to the bias electrode in each of a plurality of waveform periods CY, which are repetitions of the waveform period CY. The waveform period CY is defined by a bias frequency. The bias frequency is, for example, a frequency not less than 50 kHz and not more than 27 MHz. The time length of the waveform period CY is the reciprocal of the bias frequency.

[0028] As shown in FIG. 4(a), the electrical bias EB may be bias high frequency power LF having a bias frequency. That is, the electrical bias EB may have a sinusoidal waveform whose frequency is the bias frequency. In this case, the bias power supply 32 is electrically connected to the bias electrode via a matching box 34. The variable impedance of the matching box 34 is set to reduce reflection of the bias high frequency power LF from the load.

[0029] Alternatively, as shown in FIG. 4(b), the electrical bias EB may include a voltage pulse VP. The voltage pulse VP is applied to the bias electrode within a waveform period CY. The voltage pulse VP is periodically applied to the bias electrode at time intervals equal to the time length of the waveform period CY. The waveform of the voltage pulse VP may be a square wave, a triangular wave, or any other waveform. The polarity of the voltage pulse VP is set so as to generate a potential difference between the substrate W and the plasma, thereby attracting ions from the plasma to the substrate W. The voltage pulse VP is applied to the bias electrode so that the waveform period CY includes a period during which the potential of the substrate W is negative. The voltage pulse VP applied to the bias electrode may have a negative potential, a positive potential, or a potential that changes between a positive potential and a negative potential. The voltage pulse VP may be a negative voltage pulse or a negative DC voltage pulse. Note that when the electrical bias EB is a voltage pulse VP, the plasma processing apparatus 1 does not need to include a matching unit 34.

[0030] In one embodiment, the bias power supply 32 may include a signal generator 32g, a D / A converter 32c, and an amplifier 32a, as shown in Figure 3. The signal generator 32g periodically generates a bias signal having a specified waveform and waveform period CY. The signal generator 32g may be comprised of a programmable processor or a programmable logic device such as an FPGA.

[0031] The output of the signal generator 32g is connected to the input of the D / A converter 32c. The D / A converter 32c converts the bias signal from the signal generator 32g into an analog signal. The output of the D / A converter 32c is connected to the input of the amplifier 32a. The amplifier 32a amplifies the analog signal from the D / A converter 32c to generate the electrical bias EB. The gain of the amplifier 32a is specified by the control unit 2 to the bias power supply 32. Note that the bias power supply 32 does not need to include the D / A converter 32c. In this case, the output of the signal generator 32g is connected to the input of the amplifier 32a, and the amplifier 32a amplifies the bias signal from the signal generator 32g to generate the electrical bias EB. Note that if the electrical bias EB is a voltage pulse VP, the bias power supply 32 may periodically generate the voltage pulse VP by periodically switching its output voltage between the output voltage of the high-voltage power supply and ground potential or another potential.

[0032] The high frequency power supply 31 is configured to generate a source frequency f within a waveform period CY that most effectively suppresses the degree of reflection of the source high frequency power HF. S The optimal time-varying pattern of the source frequency f S The source frequency f S The process of identifying the optimal time-varying pattern of the source frequency f is called the "optimization process." In the optimization process, the high-frequency power supply 31 adjusts the source frequency f at a plurality of discrete points (phases) in each waveform period CY in the time series. S Alternatively, the high frequency power supply 31 may set the source frequency f continuously in time within each waveform period CY in the time series of the plurality of waveform periods CY.S The calculation for the optimization process may be performed by the signal generator 31g of the high frequency power supply 31. The calculation for the optimization process may also be performed by the control unit 2.

[0033] The plasma processing apparatus 1 may further include a sensor 35 and / or a sensor 36 for determining the degree of reflection of the source high frequency power HF in the optimization process (see FIG. 2). The sensor 35 is configured to measure the power level Pr of the reflected wave of the source high frequency power HF from the load. The sensor 35 includes, for example, a directional coupler. The directional coupler may be provided between the high frequency power supply 31 and the matching box 33. The sensor 35 may further be configured to measure the power level Pf of the forward wave of the source high frequency power HF. The power level Pr of the reflected wave measured by the sensor 35 is notified to the high frequency power supply 31. In addition, the power level Pf of the forward wave may be notified from the sensor 35 to the high frequency power supply 31.

[0034] The sensor 36 includes a voltage sensor and a current sensor. The sensor 36 detects the voltage V in the power supply path connecting the high frequency power supply 31 and the high frequency electrode. S and current I S The source high frequency power HF is supplied to the high frequency electrode via this power supply line. The sensor 36 may be provided between the high frequency power supply 31 and the matching box 33. The voltage V S and current I S is notified to the high frequency power supply 31.

[0035] The high frequency power supply 31 generates a representative value from the notified measurement value. The measurement value may be the power level Pr of the reflected wave acquired by the sensor 35. The measurement value may also be the ratio of the power level Pr of the reflected wave to the output power level of the source high frequency power HF (i.e., the reflectivity). The measurement value may be the voltage V acquired by the sensor 36. S and current I S The measured value may be the impedance Z of the load side of the high frequency power supply 31 in each of the multiple phase periods SP. LImpedance Z L is the voltage V obtained by the sensor 36 S and current I S The measured value is determined from the impedance Z L and the output impedance of the high frequency power source 31. The representative value represents the degree of reflection of the source high frequency power HF in each waveform period CY. The representative value may be the average or maximum value of the measured values ​​in each waveform period CY. Alternatively, the representative value may be the reflection coefficient calculated from the reflection of the source frequency f S Alternatively, the average or maximum value of the measured values ​​in a part of the period in which the value is changed may be used.

[0036] The optimization process will be described in detail below with reference to Figs. 5 to 8. Each of Figs. 5 to 8 is a diagram for explaining an example of optimization process of the time change pattern of the source frequency. The optimization process includes, in order, a first optimization process, ..., a Jth optimization process. J may be any integer equal to or greater than 2. In the example shown in Figs. 5 to 7, J is 3.

[0037] In the optimization process, the high frequency power source 31 searches for an optimal time-varying pattern in a time series of a plurality of waveform periods CY. In the optimization process, the high frequency power source 31 searches for an optimal time-varying pattern in a time series of a plurality of waveform periods CY. S The time pattern of the source frequency f S The initial time pattern is used.

[0038] Next, the high frequency power supply 31 performs a first optimization process. In the first optimization process, the high frequency power supply 31 optimizes the source frequency f S Identify a first time-varying pattern of

[0039] In the first optimization process, the high frequency power supply 31 optimizes the source frequency f at each of a plurality of first time points (phases) within each waveform period CY in the time series. S and the interpolated source frequency f in each of the plurality of first division periods DP1 Sand the source frequency f S The time-varying pattern is used.

[0040] The number of the first time points in each waveform period CY is 2 or more. In the example shown in FIG. 5, the first time points include time points T 11 ~Time T 13 The waveform period CY is divided into a plurality of first divided periods DP1 by a plurality of first points in time. In the example shown in FIG. 5, the plurality of first divided periods DP1 are divided into a plurality of first divided periods DP1 by a plurality of first points in time T 11 and time T 12 The period between time T 12 and time T 13 and the time T 13 and the final time point T within the waveform period CY E The first time point T 11 The source frequency f S and the final time point T E The source frequency f S are identical.

[0041] The multiple first points in time (phases) within each waveform period CY may be predetermined. Alternatively, the multiple first points in time may be set such that each of the multiple first divided periods DP1 has a first change amount as the change amount in the load impedance of the high frequency power supply 31 with respect to the initial time pattern described above. Alternatively, the multiple first points in time may be set such that each of the multiple first divided periods DP1 has a first change amount as the change amount in the source frequency with respect to the initial time pattern described above. Alternatively, the multiple first points in time may be set such that the waveform period CY is divided into more divided periods as the section within the waveform period CY has a greater load impedance of the high frequency power supply 31 or a greater degree of reflection of the source high frequency power HF. Alternatively, if the electrical bias EB includes a voltage pulse VP, the multiple first points in time may be set such that the waveform period CY is divided into more divided periods as the section within the waveform period CY has a greater change amount in the voltage at the substrate support 11 in response to the voltage pulse VP. Alternatively, if the electrical bias EB includes a voltage pulse VP, one of the multiple first divided periods DP1 may include a period during which the voltage pulse VP is supplied to the substrate support 11.

[0042] In the first optimization process, the high frequency power supply 31 optimizes the waveform period CY m The source frequency f S The waveform period CY precedes the time change pattern of m-M1 Source frequency f within S Specifically, the high frequency power supply 31 changes the source frequency f at each of a plurality of first time points in the time series of a plurality of waveform periods CY. S More specifically, the high frequency power supply 31 sequentially changes the waveform period CY m The first time point T in 1n The source frequency f S [m,T 1n ], the preceding waveform around CY m-M1 The first time point T in 1n The source frequency f S [m-M1,T 1n ] is set to a frequency that has one change. The one change is a decrease or an increase in frequency. Note that "m" is a natural number that represents the order of the waveform period CY in the time series. "n" is a natural number that represents the order of each of the multiple first time points in the waveform period CY. "M1" is an integer equal to or greater than 1, for example, 1. Also, f S [m,T 1n ] is the waveform period CY m The first time point T in 1n The source frequency f S Represents.

[0043] The high frequency power supply 31 generates a source frequency f S , a plurality of first time points and a time point T E The source frequency f S and the source frequency f immediately after S The high frequency power supply 31 is interpolated from the source frequency f S Alternatively, the high frequency power supply 31 may use a linear interpolation to interpolate the source frequency f S In the example shown in FIG. 5, the first time point T 12 The source frequency fS The situation where the is changed is shown.

[0044] In the first optimization process, when the degree of reflection of the source high frequency power HF is reduced due to one of the changes described above, the high frequency power source 31 adjusts the subsequent waveform period CY m+M1 Source frequency f within S [m+M1,T 1n ], the source frequency f S [m,T 1n When the degree of reflection of the source high frequency power HF increases due to the one-way change, the high frequency power supply 31 sets the frequency to a frequency that has a one-way change with respect to the subsequent waveform period CY m+M1 Frequency f S [m+M1,T 1n ], the source frequency f S [m,T 1n ] is set to a frequency with the other change being a decrease or increase in frequency, which is the opposite change to the one change.

[0045] In order to identify the first time-varying pattern in the first optimization process, the high-frequency power source 31 adjusts the source frequency f at each of a plurality of first time points so as to suppress the degree of reflection of the source high-frequency power HF. S Alternatively, the high frequency power supply 31 may sequentially optimize the source frequency f at each of a plurality of first time points to identify the first time-varying pattern. S In any case, the first time-varying pattern may be determined by repeatedly adjusting (or varying) the source frequency f S The order of the time points at which the source frequency f is optimized or adjusted may be predetermined or may be any order. For example, S The source frequency f is chosen in order from the point where it is empirically known that changing the S may be optimized or adjusted.

[0046] In the first optimization process, the high frequency power source 31 determines the source frequency f of the waveform period CY when the degree of reflection of the source high frequency power HF satisfies the first condition. S The time-varying pattern of the first condition is identified as a first time-varying pattern. The first condition is predetermined as a condition indicating that the degree of reflection of the source high frequency power HF is sufficiently suppressed. For example, the first condition may be satisfied when the degree of reflection of the source high frequency power HF is within a first acceptable range. In FIG. 5, the initial time-varying pattern is indicated by a solid line, and the time-varying pattern used in the first optimization process is indicated by a dashed line.

[0047] The high frequency power supply 31 performs a second optimization process after the first optimization process. In the second optimization process, the high frequency power supply 31 optimizes the source frequency f in the waveform cycle CY that most effectively suppresses the reflection of the source high frequency power HF based on the first reference pattern. S The first reference pattern may be a second time-varying pattern of the first time-varying pattern or a source frequency f generated from the first time-varying pattern. S This is the first derived time pattern of

[0048] In the second optimization process, the high frequency power supply 31 optimizes the source frequency f at each of the plurality of second time points (phases) within each waveform period CY in the time series. S and the interpolated source frequency f in each of the plurality of second division periods DP2 S and the source frequency f S The time-varying pattern is used.

[0049] The number of the second time points in each waveform period CY is greater than the number of the first time points in each waveform period CY in the first optimization process. In the example shown in FIG. 6, the second time points are time points T 21 ~Time T 27The waveform period CY is divided into a plurality of second divided periods DP2 by a plurality of second time points. The number of the plurality of second divided periods DP2 in each waveform period CY is greater than the number of the plurality of first divided periods DP1 in the waveform period CY in the first optimization process. In the example shown in FIG. 6, the plurality of second divided periods DP2 are divided into a plurality of second divided periods DP2 by a plurality of second time points T 21 and time T 22 The period between time T 22 and time T 23 The period between time T 23 and time T 24 The period between time T 24 and time T 25 The period between time T 25 and time T 26 The period between time T 26 and time T 27 and the time T 27 and the final time point T within the waveform period CY E The first second time point T 21 The source frequency f S and the final time point T E The source frequency f S are identical.

[0050] The multiple second points in time (phases) within each waveform period CY may be predetermined. Alternatively, the multiple second points in time may be set such that each of the multiple second divided periods DP2 has a second change amount as the change amount of the load impedance of the high frequency power supply 31 with respect to the first reference pattern. In this case, the second change amount is smaller than the first change amount. Alternatively, the multiple second points in time may be set such that each of the multiple second divided periods DP2 has a second change amount as the change amount of the source frequency with respect to the first reference pattern. In this case, the second change amount is also smaller than the first change amount. Alternatively, the multiple second points in time may be set such that the waveform period CY is divided into more divided periods as the section within the waveform period CY has a larger load impedance of the high frequency power supply 31 or a larger degree of reflection of the source high frequency power HF. Alternatively, if the electrical bias EB includes a voltage pulse VP, the multiple second points in time may be set such that the waveform period CY is divided into more divided periods as the section within the waveform period CY has a larger change amount of the voltage at the substrate support 11 in response to the voltage pulse VP. The second points of time may include the same points of time as the first points of time within the waveform period CY.

[0051] In the second optimization process, the high frequency power supply 31 optimizes the waveform period CY m The source frequency f S The waveform period CY precedes the time change pattern of m-M2 Source frequency f within S In the initial stage of the second optimization process, the source frequency f of the waveform period CY is changed from the time-varying pattern of S The time-varying pattern is obtained by modifying the first reference pattern.

[0052] Specifically, the high frequency power supply 31 generates a source frequency f S More specifically, in the second optimization process, the high frequency power supply 31 sequentially changes the waveform period CY m The second time point T 2n The source frequency f S [m,T 2n], the preceding waveform around CY m-M2 The second time point T 2n The source frequency f S [m-M2,T 2n ] is set to a frequency that has one change. One change is a decrease or an increase in frequency. "m" is a natural number that represents the order of the waveform period CY in the time series. "n" is a natural number that represents the order of each of the multiple second time points in the waveform period CY. "M2" is an integer equal to or greater than 1, for example, 1. Also, f S [m,T 2n ] is the waveform period CY m The second time point T 2n The source frequency f S Represents.

[0053] The high frequency power supply 31 generates a source frequency f S , at a plurality of second time points and at time point T E The source frequency f S and the source frequency f immediately after S The high frequency power supply 31 is interpolated from the source frequency f S Alternatively, the high frequency power supply 31 may use a linear interpolation to interpolate the source frequency f S In the interpolation, a high-order interpolation may be used.

[0054] In the second optimization process, when the degree of reflection of the source high frequency power HF is reduced due to one of the changes described above, the high frequency power source 31 adjusts the subsequent waveform period CY m+M2 Source frequency f within S [m+M2,T 2n ], the source frequency f S [m,T 2n When the degree of reflection of the source high frequency power HF increases due to the one-way change, the high frequency power supply 31 sets the frequency to a frequency that has a one-way change with respect to the subsequent waveform period CY m+M2 Frequency f S [m+M2,T 2n ], the source frequency f S [m,T 2n] is set to a frequency with the other change being a decrease or increase in frequency, which is the opposite change to the one change.

[0055] In order to identify the second time-varying pattern in the second optimization process, the high-frequency power source 31 adjusts the source frequency f at each of a plurality of second time points so as to suppress the degree of reflection of the source high-frequency power HF. S Alternatively, the high frequency power supply 31 may sequentially optimize the source frequency f at each of a plurality of second time points to identify the second time-varying pattern. S In either case, the source frequency f S The order of the time points at which the source frequency f is optimized or adjusted may be predetermined or may be any order. For example, S The source frequency f is chosen in order from the point where it is empirically known that changing the S may be optimized or adjusted.

[0056] In the second optimization process, the high frequency power source 31 determines the source frequency f of the waveform period CY when the degree of reflection of the source high frequency power HF satisfies the second condition. S The time-varying pattern of the first reference pattern is identified as a second time-varying pattern. The second condition is predetermined as a condition indicating that the degree of reflection of the source high frequency power HF is sufficiently suppressed. For example, the second condition may be satisfied when the degree of reflection of the source high frequency power HF is within a second acceptable range. In FIG. 6, the first reference pattern is indicated by a solid line, and the time-varying pattern used in the second optimization process is indicated by a dashed line.

[0057] The high frequency power supply 31 may further perform a third optimization process after the second optimization process. Furthermore, the high frequency power supply 31 may further perform a fourth optimization process after the third optimization process. Hereinafter, the jth optimization process will be described, representing each of the second to Jth optimization processes, using "j" as the symbol indicating the order of each optimization process.

[0058] In the j-th optimization process, the high frequency power supply 31 determines the source frequency f in the waveform period CY that most effectively suppresses the degree of reflection of the source high frequency power HF based on the (j-1)-th reference pattern. S The (j-1)th reference pattern is the (j-1)th time-varying pattern or the source frequency f generated from the (j-1)th time-varying pattern. S is the (j-1)th derived time pattern of

[0059] In the j-th optimization process, the high-frequency power supply 31 calculates the source frequency f at each of a plurality of j-th points (phases) within each waveform period CY in the time series. S and multiple jth division periods DP j The interpolated source frequency f S and the source frequency f S The time-varying pattern is used.

[0060] The number of j-th time points in each waveform period CY is greater than the number of j-th time points in each waveform period CY in the (j-1)th optimization process. The waveform period CY is divided into j-th divided periods DP j Each waveform period CY is divided into a plurality of j-th divided periods DP j The number of divided periods DP within the waveform period CY in the (j-1)th optimization process is (j-1) The number of the first jth time point T in the waveform period CY is greater than the number of j1 The source frequency f S and the final time point T E The source frequency f S are identical.

[0061] In the example shown in FIG. 7, the plurality of third time points are time points T 31 ~Time T 3b In the example shown in FIG. 7, the plurality of third divided periods DP3 includes the time T 31 and time T 32 The period between time T 32 and time T 33 The period between time T 33 and time T 34 The period between time T 34 and time T 35 The period between time T 35 and time T 36 The period between 36 and time T 37 The period between 37 and time T 38 The period between 37 and time T 38 The period between 38 and time T 39 The period between 39 and time T 3a The period between 3a and time T 3b The period between time T 3b and the final time point T within the waveform period CY E The source frequency f at the first third time point T31 within the waveform period CY includes the period between S and the final time point T E The source frequency f S are identical.

[0062] The j-th time points (phases) in each waveform period CY may be predetermined. Alternatively, the j-th time points may be determined by dividing the j-th divided periods DP j may be set so that each of the j-th time points has a j-th change amount as a change amount of the load impedance of the high frequency power supply 31. In this case, the j-th change amount is smaller than the (j-1)-th change amount. Alternatively, the j-th time points may be set so that each of the j-th time points has a j-th change amount as a change amount of the load impedance of the high frequency power supply 31. jmay be set so that each of the jth time points has the jth change amount as the change amount of the source frequency. Even in this case, the jth change amount is smaller than the (j-1)th change amount. Alternatively, the jth time points may be set so that the greater the load impedance of the high frequency power supply 31 or the degree of reflection of the source high frequency power HF within the waveform period CY, the greater the number of divided periods. Alternatively, if the electric bias EB includes a voltage pulse VP, the jth time points may be set so that the greater the number of divided periods within the waveform period CY, the greater the amount of change in voltage at the substrate support 11 in response to the voltage pulse VP. Note that the jth time points may include the same time points as the (j-1)th time points within the waveform period CY.

[0063] In the jth optimization process, the high frequency power supply 31 adjusts the waveform period CY m The source frequency f S The waveform period CY precedes the time change pattern of m-Mj Source frequency f within S In the initial stage of the second optimization process, the source frequency f of the waveform period CY is changed from the time-varying pattern of S The time-varying pattern of is obtained by changing the (j-1)th reference pattern.

[0064] Specifically, the high frequency power supply 31 generates a source frequency f S More specifically, in the j-th optimization process, the high frequency power supply 31 changes the waveform period CY m At the jth time point T jn The source frequency f S [m,T jn ], the preceding waveform around CY m-Mj At the jth time point T jn The source frequency f S [m-Mj,T jn] is set to a frequency that has one change. One change is a decrease or an increase in frequency. "m" is a natural number that represents the order of the waveform period CY in the time series. "n" is a natural number that represents the order of each of the multiple j-th time points in the waveform period CY. "Mj" is an integer equal to or greater than 1, for example, 1. Also, f S [m,T jn ] is the waveform period CY m At the jth time point T jn The source frequency f S Represents.

[0065] The high frequency power supply 31 generates a plurality of j-th divided periods DP j The source frequency f in each of S , multiple j-th time points and time point T E The source frequency f S and the source frequency f immediately after S The high frequency power supply 31 is interpolated from the source frequency f S Alternatively, the high frequency power supply 31 may use a linear interpolation to interpolate the source frequency f S In the interpolation, a high-order interpolation may be used.

[0066] In the jth optimization process, when the degree of reflection of the source high frequency power HF is reduced due to one of the changes described above, the high frequency power source 31 reduces the subsequent waveform period CY m+Mj Source frequency f within S [m+Mj,T jn ], the source frequency f S [m,T jn When the degree of reflection of the source high frequency power HF increases due to the one-way change, the high frequency power supply 31 sets the frequency to a frequency that has a one-way change with respect to the subsequent waveform period CY m+Mj Frequency f S [m+Mj,T jn ], the source frequency f S [m,T jn ] is set to a frequency with the other change being a decrease or increase in frequency, which is the opposite change to the one change.

[0067] In order to identify the jth time-varying pattern in the jth optimization process, the high frequency power supply 31 adjusts the source frequency f at each of a plurality of jth time points so as to suppress the degree of reflection of the source high frequency power HF. S Alternatively, the high frequency power supply 31 may sequentially optimize the source frequency f at each of a plurality of j-th time points in order to identify the j-th time change pattern. S In either case, the jth time-varying pattern may be identified by repeatedly adjusting (or varying) the source frequency f S The order of the time points at which the source frequency f is optimized or adjusted may be predetermined or may be any order. For example, S The source frequency f is chosen in order from the point where it is empirically known that changing the S may be optimized or adjusted.

[0068] The high frequency power supply 31 determines the source frequency f of the waveform period CY when the degree of reflection of the source high frequency power HF satisfies the jth condition in the jth optimization process. S The time change pattern of is identified as the jth time change pattern. The jth condition is predetermined as a condition indicating that the degree of reflection of the source high frequency power HF is sufficiently suppressed. For example, the jth condition may be satisfied when the degree of reflection of the source high frequency power HF is within the jth allowable range. In FIG. 7, the third reference pattern is indicated by a solid line, and the time change pattern used in the third optimization process is indicated by a dashed line.

[0069] The high frequency power supply 31 can use the time change pattern obtained by the final optimization process that most suppresses the degree of reflection within the waveform period CY as the optimal time change pattern, and use it in the subsequent waveform period CY in the time series.

[0070] In one embodiment, if the degree of reflection of the source high frequency power HF becomes so large that it does not satisfy a predetermined condition while performing the jth optimization process (j is an integer equal to or greater than 2), the high frequency power supply 31 may perform the first optimization process again. Thereafter, the high frequency power supply 31 may further perform the second to Jth optimization processes. According to this embodiment, if an abnormal plasma discharge occurs during the jth optimization process, it is possible to again search for a time-varying pattern of the source frequency HF that suppresses the degree of reflection of the source high frequency power HF within the waveform period CY.

[0071] In one embodiment, the high frequency power supply 31 adjusts the source frequency f from the (j-1) time change pattern after the (j-1)th optimization process and before the jth optimization process. S The (j-1)th derived time pattern of the time series may be obtained.

[0072] Specifically, the high frequency power source 31 shifts the (j-1)th time change pattern in the time direction in multiple waveform periods CY in the time series. The minimum amount of shift in the time direction may be smaller than the time pitch of multiple discrete time points at which the source frequency is set in the waveform period CY. The high frequency power source 31 may identify, from among multiple time change patterns obtained by shifting the (j-1)th time change pattern in the time direction, the time change pattern that best suppresses the degree of reflection of the source high frequency power HF in the waveform period CY as the (j-1)th derived time pattern. The (j-1)th derived time pattern may be used as the (j-1)th reference pattern in the jth optimization process.

[0073] In the example shown in FIG. 8, the high-frequency power supply 31 adjusts the source frequency f from the first time-varying pattern after the first optimization process and before the second optimization process. SThe RF power source 31 shifts the first time-varying pattern in the time direction for multiple waveform periods CY in the time series. The RF power source 31 may identify, as the first derived time pattern, the time-varying pattern that best suppresses the degree of reflection of the source RF power HF from among multiple time-varying patterns obtained by shifting the first time-varying pattern in the time direction. The first derived time pattern may be used as a first reference pattern in the second optimization process. In FIG. 8, the solid line indicates the first time-varying pattern, and the dashed line indicates multiple time-varying patterns obtained by shifting the first time-varying pattern in the time direction.

[0074] The source frequency f in the waveform period CY S The above-described process of identifying a time-varying pattern that suppresses reflections by shifting the time-varying pattern in the time direction may be used at any timing in each of the first to J-th optimization processes.

[0075] In one embodiment, the source radio frequency power HF and the electrical bias EB are supplied simultaneously and continuously. That is, in one embodiment, a continuous wave of the source radio frequency power HF and a continuous wave of the electrical bias EB are supplied simultaneously. When the continuous wave of the source radio frequency power HF and the continuous wave of the electrical bias EB are supplied simultaneously, a first process, which is one type of the optimization process described above, is applied. In the first process, the optimization process described above is applied to a plurality of consecutive waveform periods CY as the plurality of waveform periods CY in the time series described above.

[0076] In another embodiment, the bias power supply 32 periodically supplies pulses EBP of an electrical bias EB to the bias electrode. The pulses EBP are supplied to the bias electrode in each of a plurality of pulse periods PP. Each of the plurality of pulse periods PP includes a repeating waveform period CY. That is, during each of the plurality of pulse periods PP, the electrical bias EB is periodically supplied to the bias electrode.

[0077] Here, reference is made to Figures 9(a), 9(b), 10(a), and 10(b). Figures 9(a), 9(b), 10(a), and 10(b) are timing charts of examples of source RF power HF and electrical bias EB. In these figures, "ON" for source RF power HF indicates that source RF power HF is being supplied, and "OFF" for source RF power HF indicates that the supply of source RF power HF is stopped. Also, in these figures, "ON" for electrical bias EB indicates that electrical bias EB is being applied to the bias electrode, and "OFF" for electrical bias EB indicates that electrical bias EB is not being applied to the bias electrode. Also, in these figures, "HIGH" for electrical bias EB indicates that an electrical bias EB having a level higher than the level of electrical bias EB indicated by "LOW" is being applied to the bias electrode.

[0078] The multiple pulse periods PP appear in time sequence. The multiple pulse periods PP appear in time sequence at time intervals (periods) that are the reciprocal of the pulse frequency. In the following description, the pulse period PP k represents the kth pulse period among the multiple pulse periods PP. The pulse frequency is lower than the bias frequency, for example, a frequency of 1 kHz or more and 100 kHz or less. As described above, the electric bias EB is periodically applied to the bias electrode in each of the multiple pulse periods PP. In periods other than the multiple pulse periods PP, the electric bias EB may not be applied to the bias electrode. Alternatively, an electric bias EB having a level lower than the level of the electric bias EB in the multiple pulse periods PP may be applied to the bias electrode in periods other than the multiple pulse periods PP.

[0079] As shown in Figure 9(a), the source radio frequency power HF may be supplied as a continuous wave. In the example shown in Figure 9(a), multiple overlapping periods OP during which the source radio frequency power HF and the electrical bias EB are simultaneously supplied each coincide with multiple pulse periods PP.

[0080] Alternatively, as shown in Figures 9(b), 10(a), and 10(b), pulses of source radio frequency power HF may be supplied. As shown in Figure 9(b), pulses of source radio frequency power HF may be supplied in each of a plurality of periods that respectively coincide with a plurality of pulse periods PP. In the example shown in Figure 9(b), a plurality of overlap periods OP in which source radio frequency power HF and electrical bias EB are supplied simultaneously each coincide with a plurality of pulse periods PP. As shown in Figures 10(a) and 10(b), pulses of source radio frequency power HF may be supplied in each of a plurality of periods that respectively partially overlap with a plurality of pulse periods PP. In the examples shown in Figures 10(a) and 10(b), each of a plurality of overlap periods OP in which source radio frequency power HF and electrical bias EB are supplied simultaneously is a part of a corresponding pulse period PP among a plurality of pulse periods PP. In the following description, overlap periods OP k represents the k-th overlap period among the multiple overlap periods OP. Also, the waveform period CY m represents the m-th waveform period among the plurality of waveform periods CY in each of the plurality of overlap periods OP.

[0081] The optimization process when the bias power supply 32 periodically supplies pulses EBP of the electric bias EB to the bias electrode will be described below with reference to (a) to (c) of Figure 11. (a) to (c) of Figure 11 are timing charts of examples of the electric bias.

[0082] The high frequency power supply 31 operates during the overlapping periods OP1 to OP Ka The waveform periods CY1 to CY Ma Each source frequency f S As the time pattern, a previously prepared initial time pattern is used. Note that Ka is an integer equal to or greater than 1, for example, 5. Also, Ma is an integer equal to or greater than 1.

[0083] The high frequency power supply 31 generates a time series of a plurality of consecutive waveform periods CY, each of which has an overlap period OP1 to OP2. Ka The waveform period CY in each Ma+1~Waveform period CY M The first process is performed on

[0084] Overlapping period OP Ka+1 In the final overlap period, the high frequency power supply 31 applies the second process to each of the plurality of time series. Ka+1 ~ Waveform period CY1 in each of the final overlap periods ~ Waveform period CY Mb The waveform period CY of the same order m That is, the plurality of time series include first to Mb-th time series, where Mb is an integer equal to or greater than 1. Each of the plurality of time series includes a plurality of waveform periods CY. Specifically, the first time series includes an overlap period OP. Ka+1 ~The second time series includes waveform periods CY1 within each of the final overlap periods OP. Ka+1 ~The waveform period CY2 in each of the final overlap periods is included. The Mb time series includes the overlap period OP Ka+1 ~ Waveform period CY in each of the final overlap periods Mb In the second process, each of the plurality of time series is a time series of a plurality of waveform periods CY to which the above-described optimization processes (that is, the first optimization process to the J-th optimization process) are applied.

[0085] The high frequency power supply 31 also generates a time series of a plurality of consecutive waveform periods CY, each of which has an overlap period OP. Ka+1 ~ Waveform period CY within each of the final overlap periods Mb+1 ~Waveform period CY M The first process described above is applied to

[0086] According to the plasma processing apparatus 1 described above, it is possible to reduce the degree of reflection of the source high frequency power HF in the waveform cycle CY. Furthermore, according to the plasma processing apparatus 1, the source frequency f S can be smoothly varied.

[0087] A frequency control method according to one exemplary embodiment will be described below with reference to Figs. 12 to 14. Fig. 12 is a flowchart of a frequency control method according to one exemplary embodiment. Figs. 13 and 14 are each a flowchart showing an example of step STA of a frequency control method according to one exemplary embodiment. The frequency control method shown in Fig. 12 (hereinafter referred to as "method MT") can be performed using a plasma processing apparatus 1. In method MT, each part of the plasma processing apparatus 1 can be controlled by a control unit 2.

[0088] The method MT begins with step STA, in which a source radio frequency power HF is supplied from the radio frequency power supply 31 to generate plasma from the gas in the chamber 10. In step STB, an electrical bias EB is supplied to the bias electrode of the substrate support 11. Step STA is performed while step STB is being performed.

[0089] As shown in FIGS. 13 and 14, in step STa of the process STA, in one or several initial waveform periods CY in the time series of a plurality of waveform periods CY, the above-mentioned initial time pattern is S It is used as a time pattern.

[0090] Next, in steps STb to STc of the process STA, a first optimization process is performed. In the first optimization process, as described above, the source frequencies f S While the source frequency f is changed at each of the plurality of first time points, S and the interpolated source frequency in each of the plurality of first division periods DP1 are used.

[0091] In step STb, as described above in the first optimization process, the waveform period CY m The source frequency f S The time change pattern of the preceding waveform period CY m-M1 Source frequency f within S The time-varying pattern of the

[0092] In the subsequent step STJa, it is determined whether the reflection degree of the source high frequency power HF satisfies the first condition described above. If the first condition is not satisfied, step STb is performed again. If the first condition is satisfied, the time change pattern finally obtained in the first optimization process is identified as the first time change pattern described above in step STc.

[0093] The method MT may include step STd, which is performed after the first optimization process and before the second optimization process, in which, as described above, a time-varying pattern that best suppresses the degree of reflection of the source high frequency power HF is identified as a first derived time pattern from a plurality of time-varying patterns obtained by shifting the first time-varying pattern in the time direction.

[0094] In steps STe to STf of the method MT, the second optimization process is performed. In the second optimization process, as described above, the source frequency f S While the source frequency f is changed, S and the interpolated source frequency in each of the plurality of second division periods DP2 are used.

[0095] In step STe, as described above in the second optimization process, the waveform period CY m The source frequency f S The time change pattern of the preceding waveform period CY m-M2 Source frequency f within S At the beginning of the second optimization process, the source frequency f of the waveform period CY is changed from the time-varying pattern of S The time-varying pattern is obtained by modifying the first reference pattern.

[0096] Step STe may be followed by step STJb, in which the changed source frequency f S The time change pattern of the waveform period CY mBy using the STJb, it is determined whether the degree of reflection of the source high frequency power HF has become so large that it does not satisfy the predetermined condition. S The time change pattern of the waveform period CY m If it is determined that the degree of reflection of the source high frequency power HF has become so large that it does not satisfy the predetermined condition, the process returns to step STa. On the other hand, if the result of the determination in step STb is that the changed source frequency f S The time change pattern of the waveform period CY m If the degree of reflection of the source high frequency power HF does not become so large as to not satisfy the predetermined condition due to the use of the filter in step STJc, the process proceeds to step STJc.

[0097] In the subsequent step STJc, it is determined whether the reflection degree of the source high frequency power HF satisfies the second condition described above. If the second condition is not satisfied, step STe is performed again. If the second condition is satisfied, the time change pattern finally obtained in the second optimization process is identified as the second time change pattern described above in step STf.

[0098] The method MT may further include steps STg to STh. In steps STg to STh, a third optimization process is performed. In the third optimization process, as described above, the source frequency f S While the source frequency f is changed, S and the interpolated source frequency in each of the plurality of third division periods DP3 are used.

[0099] In the step STg, as described above in the third optimization process, the waveform period CY m The source frequency f S The time change pattern of the preceding waveform period CY m-M3 Source frequency f within S In the initial stage of the third optimization process, the source frequency f of the waveform period CY is changed from the time-varying pattern of SThe time-varying pattern of is obtained by modifying the second reference pattern.

[0100] Step STg may be followed by step STJd, in which the modified source frequency f S The time change pattern of the waveform period CY m By using STJd, it is determined whether the degree of reflection of the source high frequency power HF has become so large that it does not satisfy the predetermined condition. S The time change pattern of the waveform period CY m If it is determined that the degree of reflection of the source high frequency power HF has become so large that it does not satisfy the predetermined condition, the process returns to step STa. On the other hand, if the result of the determination in step STJd is that the changed source frequency f S The time change pattern of the waveform period CY m If the degree of reflection of the source high frequency power HF does not become so large as to not satisfy the predetermined condition by using the filter 100 in step STJe, the process proceeds to step STJe.

[0101] In the subsequent step STJe, it is determined whether the reflection degree of the source high frequency power HF satisfies the third condition described above. If the third condition is not satisfied, step STg is performed again. If the third condition is satisfied, the time change pattern finally obtained in the third optimization process is identified as the third time change pattern described above in step STh.

[0102] The method MT may end after step STh. Alternatively, the method MT may further include the fourth to Jth optimization processes as described above. For the fourth to Jth optimization processes, see the description of the jth optimization process described above.

[0103] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0104] In other embodiments, the plasma processing apparatus may be an inductively coupled plasma processing apparatus, an ECR plasma processing apparatus, a helicon wave excited plasma processing apparatus, or a surface wave plasma processing apparatus. In any of these plasma processing apparatuses, a source high frequency power HF is used to generate the plasma.

[0105] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E16] below.

[0106] [E1] a chamber; a substrate support disposed within the chamber; a radio frequency power source configured to provide a source radio frequency power to generate a plasma from the gas within the chamber; a bias power supply configured to supply an electrical bias having a waveform period to the substrate support; Equipped with The high frequency power source is While changing the source frequency of the source high frequency power at each of a plurality of first time points within the waveform period, a first time-varying pattern of the source frequency in the waveform period that most effectively suppresses the degree of reflection of the source high frequency power is identified using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first divided periods of the waveform period divided by the plurality of first time points; changing the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period relative to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern, and using the source frequency at each of the plurality of second time points and an interpolated source frequency within each of a plurality of second divided periods of the waveform period divided by the plurality of second time points, identifying a second time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power. It is structured as follows: the number of the plurality of second divided periods is greater than the number of the plurality of first divided periods; Plasma processing equipment.

[0107] [E2] The high frequency power source is optimizing the source frequency at each of the plurality of first time points in sequence to reduce a degree of reflection of the source high frequency power to identify the first time-varying pattern; optimizing the source frequency at each of the plurality of second time points in sequence to reduce the degree of reflection of the source high frequency power in order to identify the second time-varying pattern; It is configured as follows: The plasma processing apparatus according to E1.

[0108] [E3] The high frequency power source is repeatedly adjusting the source frequency at each of the plurality of first time points in sequence to identify the first time-varying pattern; repeating the step of sequentially adjusting the source frequency for each of the plurality of second time points to identify the second time-varying pattern. It is configured as follows: The plasma processing apparatus according to E1.

[0109] [E4] The plasma processing apparatus according to any one of E1 to E3, wherein the plurality of first points in time and the plurality of second points in time are determined in advance.

[0110] [E5] the plurality of first time points are set so that each of the plurality of first divided periods has a first change amount as a change amount of the load impedance of the high frequency power supply with respect to a time change pattern of the source frequency in the waveform period initially used to identify the first time change pattern; the plurality of second time points are set so that each of the plurality of second divided periods has a second change amount as a change amount of the load impedance of the high frequency power supply with respect to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern. The plasma processing apparatus according to any one of E1 to E3.

[0111] [E6] The plasma processing apparatus according to E5, wherein the second change amount is smaller than the first change amount.

[0112] [E7] the plurality of first time points are set so that each of the plurality of first divided periods has a first change amount as a change amount of the source frequency with respect to a time change pattern of the source frequency in the waveform period initially used to identify the first time change pattern; the plurality of second time points are set so that each of the plurality of second divided periods has a second change amount as the change amount of the source frequency with respect to the first time change pattern or the time change pattern created from the first time change pattern; The plasma processing apparatus according to any one of E1 to E3.

[0113] [E8] The plasma processing apparatus according to E7, wherein the second change amount is smaller than the first change amount.

[0114] [E9] The plurality of first time points and the plurality of second time points are set so that the greater the load impedance of the high frequency power source or the degree of reflection of the source high frequency power within the waveform period, the greater the number of divided periods. The plasma processing apparatus according to any one of E1 to E3.

[0115] [E10] The electrical bias is a bias high frequency power having the waveform period, or includes a voltage pulse generated at a time interval equal to the time length of the waveform period. The plasma processing apparatus according to any one of E1 to E9.

[0116] [E11] the electrical bias includes voltage pulses generated at time intervals equal to the time length of the waveform period; the plurality of first time points and the plurality of second time points are set such that a section within the waveform period is divided into a greater number of divided periods as the amount of change in voltage at the substrate support part in response to the voltage pulse increases. The plasma processing apparatus according to any one of E1 to E3.

[0117] [E12] the electrical bias includes voltage pulses generated at time intervals equal to the time length of the waveform period; one of the plurality of first divided periods includes a period during which the voltage pulse is supplied to the substrate support; The plasma processing apparatus according to any one of E1 to E4.

[0118] [E13] The plasma processing apparatus of any one of E1 to E12, wherein the high-frequency power supply is configured to use a time change pattern obtained by shifting the first time change pattern in the time direction while changing the amount of shift in the time direction to identify a time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high-frequency power, and to use the identified time change pattern as the time change pattern of the source frequency created from the first time change pattern.

[0119] [E14] The plasma processing apparatus of any one of E1 to E13, wherein the high-frequency power supply is configured to, when identifying the second time-varying pattern, re-determine the first time-varying pattern if the degree of reflection of the source high-frequency power becomes so large that it does not satisfy a predetermined standard.

[0120] [E15] a radio frequency power supply configured to generate a source radio frequency power used to generate the plasma; a bias power supply configured to generate an electrical bias used to attract ions from the plasma, the electrical bias having a waveform period; Equipped with The high frequency power source is While changing the source frequency of the source high frequency power at each of a plurality of first time points within the waveform period, a first time-varying pattern of the source frequency in the waveform period that most effectively suppresses the degree of reflection of the source high frequency power is identified using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first divided periods of the waveform period divided by the plurality of first time points; changing the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period relative to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern, and using the source frequency at each of the plurality of second time points and an interpolated source frequency within each of a plurality of second divided periods of the waveform period divided by the plurality of second time points, identifying a second time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power. It is structured as follows: the number of the plurality of second divided periods is greater than the number of the plurality of first divided periods; Power supply system.

[0121] [E16] providing a source radio frequency power from a radio frequency power source to generate a plasma from the gas within a chamber of the plasma processing device; applying an electrical bias having a waveform period to a substrate support disposed within the chamber; Including, The step of supplying source radio frequency power includes: While changing the source frequency of the source high frequency power at each of a plurality of first time points within the waveform period, using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first divided periods of the waveform period divided by the plurality of first time points, identify a first time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power; changing the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period relative to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern, and using the source frequency at each of the plurality of second time points and an interpolated source frequency within each of a plurality of second divided periods of the waveform period divided by the plurality of second time points to identify a second time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power; Including, the number of the plurality of second divided periods is greater than the number of the plurality of first divided periods; Frequency control method.

[0122] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0123] 1... plasma processing apparatus, 10... chamber, 11... substrate support part, 31... high frequency power supply, 32... bias power supply

Claims

1. a chamber; a substrate support disposed within the chamber; a radio frequency power source configured to provide a source radio frequency power to generate a plasma from the gas within the chamber; a bias power supply configured to supply an electrical bias having a waveform period to the substrate support; Equipped with The high frequency power source is While changing the source frequency of the source high frequency power at each of a plurality of first time points within the waveform period, a first time-varying pattern of the source frequency in the waveform period that most effectively suppresses the degree of reflection of the source high frequency power is identified using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first divided periods of the waveform period divided by the plurality of first time points; changing the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period with respect to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern, and using the source frequency at each of the plurality of second time points and an interpolated source frequency within each of a plurality of second divided periods of the waveform period divided by the plurality of second time points, identifying a second time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power. It is structured as follows: the number of the plurality of second divided periods is greater than the number of the plurality of first divided periods; Plasma processing equipment.

2. The high frequency power source is optimizing the source frequency at each of the plurality of first time points in sequence to reduce a degree of reflection of the source high frequency power to identify the first time-varying pattern; optimizing the source frequency at each of the plurality of second time points in sequence to reduce the degree of reflection of the source high frequency power in order to identify the second time-varying pattern; It is configured as follows: The plasma processing apparatus according to claim 1 .

3. The high frequency power source is repeatedly adjusting the source frequency at each of the plurality of first time points in sequence to identify the first time-varying pattern; repeating the step of sequentially adjusting the source frequency for each of the plurality of second time points to identify the second time-varying pattern; It is configured as follows: The plasma processing apparatus according to claim 1 .

4. 4. The plasma processing apparatus according to claim 1, wherein the plurality of first points in time and the plurality of second points in time are determined in advance.

5. the plurality of first time points are set such that each of the plurality of first divided periods has a first change amount as a change amount of the load impedance of the high frequency power supply with respect to a time change pattern of the source frequency in the waveform period initially used to identify the first time change pattern; the plurality of second time points are set so that each of the plurality of second divided periods has a second change amount as a change amount of the load impedance of the high frequency power supply with respect to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern. The plasma processing apparatus according to any one of claims 1 to 3.

6. The plasma processing apparatus of claim 5 , wherein the second change amount is smaller than the first change amount.

7. the plurality of first time points are set so that each of the plurality of first divided periods has a first change amount as a change amount of the source frequency with respect to a time change pattern of the source frequency in the waveform period initially used to identify the first time change pattern; the plurality of second time points are set so that each of the plurality of second divided periods has a second change amount as the change amount of the source frequency with respect to the first time change pattern or the time change pattern created from the first time change pattern; The plasma processing apparatus according to any one of claims 1 to 3.

8. The plasma processing apparatus of claim 7 , wherein the second change amount is smaller than the first change amount.

9. the plurality of first time points and the plurality of second time points are set so that the waveform period is divided into a greater number of divided periods as the load impedance of the high frequency power source or the degree of reflection of the source high frequency power increases. The plasma processing apparatus according to any one of claims 1 to 3.

10. The electrical bias is a bias high frequency power having the waveform period, or includes a voltage pulse generated at a time interval equal to the time length of the waveform period. The plasma processing apparatus according to any one of claims 1 to 3.

11. the electrical bias includes voltage pulses generated at time intervals equal to the time length of the waveform period; the plurality of first time points and the plurality of second time points are set such that a section within the waveform period is divided into a greater number of divided periods as the amount of change in voltage at the substrate support part in response to the voltage pulse increases. The plasma processing apparatus according to any one of claims 1 to 3.

12. the electrical bias includes voltage pulses generated at time intervals equal to the time length of the waveform period; one of the plurality of first divided periods includes a period during which the voltage pulse is supplied to the substrate support; The plasma processing apparatus according to any one of claims 1 to 3.

13. The plasma processing apparatus according to any one of claims 1 to 3, wherein the high frequency power supply is configured to use a time change pattern obtained by shifting the first time change pattern in the time direction while changing the amount of shift in the time direction to identify a time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power, and to use the identified time change pattern as the time change pattern of the source frequency created from the first time change pattern.

14. The plasma processing apparatus according to any one of claims 1 to 3, wherein the high frequency power supply is configured to, when identifying the second time change pattern, re-determine the first time change pattern if the degree of reflection of the source high frequency power becomes so large that it does not satisfy a predetermined standard.

15. a radio frequency power supply configured to generate a source radio frequency power used to generate the plasma; a bias power supply configured to generate an electrical bias used to attract ions from the plasma, the electrical bias having a waveform period; Equipped with The high frequency power source is While changing the source frequency of the source high frequency power at each of a plurality of first time points within the waveform period, a first time-varying pattern of the source frequency in the waveform period that most effectively suppresses the degree of reflection of the source high frequency power is identified using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first divided periods of the waveform period divided by the plurality of first time points; changing the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period with respect to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern, and using the source frequency at each of the plurality of second time points and an interpolated source frequency within each of a plurality of second divided periods of the waveform period divided by the plurality of second time points, identifying a second time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power. It is structured as follows: the number of the plurality of second divided periods is greater than the number of the plurality of first divided periods; Power supply system.

16. providing a source radio frequency power from a radio frequency power source to generate a plasma from the gas within a chamber of the plasma processing device; applying an electrical bias having a waveform period to a substrate support disposed within the chamber; Including, The step of supplying source radio frequency power includes: While changing the source frequency of the source high frequency power at each of a plurality of first time points within the waveform period, using the source frequency at each of the plurality of first time points and an interpolated source frequency within each of a plurality of first divided periods of the waveform period divided by the plurality of first time points, a first time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power is identified; changing the source frequency of the source high frequency power at each of a plurality of second time points within the waveform period relative to the first time change pattern or a time change pattern of the source frequency created from the first time change pattern, and using the source frequency at each of the plurality of second time points and an interpolated source frequency within each of a plurality of second divided periods of the waveform period divided by the plurality of second time points to identify a second time change pattern of the source frequency in the waveform period that most suppresses the degree of reflection of the source high frequency power; Including, the number of the plurality of second divided periods is greater than the number of the plurality of first divided periods; Frequency control method.

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