Plasma processing apparatus, power supply system, and method for controlling source frequency

Abstract

Disclosed is a plasma processing device in which a bias power supply supplies an electric bias having a waveform period to a substrate support unit. A high-frequency power supply sets a time series of the source frequency of a source high-frequency power in a frequency adjustment period to a maximum frequency in a first specific phase, a minimum frequency in a second specific phase, and an interpolated frequency in a phase other than at least two specific phases including the first specific phase and the second specific phase. The phase difference between the frequency adjustment period and the waveform period is set so as to suppress the degree of reflection of the source high-frequency power. The high-frequency power supply causes the maximum frequency in the first specific phase and the minimum frequency in the second specific phase in the time series of the source frequency in the frequency adjustment period to change in mutually opposite directions so as to suppress the degree of reflection of the source high-frequency power.

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 generate source radio frequency power having a source frequency to generate plasma from a gas within the chamber. The bias power source is configured to supply an electrical bias to the substrate support to attract ions from the plasma within the chamber. The electrical bias has a waveform period. The radio frequency power source is configured to set a time series of source frequencies within a frequency adjustment period having a time length equal to the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at at least two specific phases, including the first specific phase and the second specific phase. The radio frequency power source and the bias power source are configured to set a phase difference between the waveform period and the frequency adjustment period, in which the source frequency is changed according to an initial frequency set specifying initial source frequencies at the at least two specific phases, to suppress reflection of the source radio frequency power. After setting the phase difference, the high frequency power supply is configured to specify a source frequency at a first specific phase and a source frequency at a second specific phase that suppress the degree of reflection of the source high frequency power, while changing the maximum frequency at a first specific phase and the minimum frequency at a second specific phase in opposite directions in the time series of the source frequency within the frequency adjustment period. [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] Each of (a) to (c) of FIG. 5 is a diagram showing an example of a time series of the source frequency in a plasma processing apparatus according to one exemplary embodiment. [Figure 6] Each of (a) and (b) of FIG. 6 is a diagram showing an example of a time series of a source frequency in a plasma processing apparatus according to one exemplary embodiment. [Figure 7] 1A and 1B show examples of pulses of source radio frequency power and pulses of electrical bias. [Figure 8] Each of (a) to (d) of FIG. 8 is a diagram showing an example of a time series of the source frequency in a plasma processing apparatus according to one exemplary embodiment. [Figure 9] FIG. 9 is a flow diagram of a method for controlling a source frequency 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 or more and 150 MHz or less.

[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 and an amplifier 31a. The signal generator 31g generates a source frequency f S The signal generator 31g may be configured from a programmable processor or a programmable logic device such as a field-programmable gate array (FPGA).

[0025] The output of the signal generator 31g is connected to the input of the amplifier 31a. The amplifier 31a amplifies the high frequency signal from the signal generator 31g 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.

[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 electric 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 and attract ions from the plasma to the substrate W. The voltage pulse VP may be a negative voltage pulse or a negative DC voltage pulse. Note that when the electric bias EB is a voltage pulse VP, the plasma processing apparatus 1 does not need to include a matching device 34. In this case, the bias power supply 32 may include a power supply (e.g., a DC power supply) and a waveform generator that generates the voltage pulse VP by generating a waveform for the voltage from the power supply.

[0030] 2 and 3, each of FIGS. 5(a) to 5(c) and 6(a) to 6(b) is a diagram showing an example of a time series of the source frequency in a plasma processing apparatus according to one exemplary embodiment. The high frequency power supply 31 adjusts the source frequency f within a frequency adjustment period (hereinafter referred to as "period FC") to suppress the degree of reflection of the source high frequency power HF. S The source frequency f of the high frequency power supply 31 described below is adjusted. S The process including the adjustment may be performed by the signal generator 31g. Alternatively, the process adjustment in the high frequency power supply 31 may be performed by another control unit (for example, the control unit 2).

[0031] The period FC has the same time length as the waveform period CY and is repeated in the same manner as the waveform period CY. The period FC includes a plurality of phases. The plurality of phases may be set discretely within the period FC. The plurality of phases within the period FC includes at least two specific phases. The at least two specific phases are a specific phase α a (first specific phase) and specific phase α b (Second specific phase) Specific phase α b is a specific phase α within the period FCa The specific phase α a and the specific phase α b The phase difference between the two is predetermined.

[0032] The high frequency power supply 31 has a source frequency f within a period FC. S The time series of a specific phase α a Frequency at specific phase α b and an interpolated frequency at a phase other than at least two specific phases. S A specific phase α in the time series a The frequency at is the source frequency f within a period FC. S is the maximum frequency in the time series of the source frequency f within the period FC. S A specific phase α in the time series b The frequency at is the source frequency f within a period FC. S The high frequency power source 31 generates a source frequency f at a phase other than at least two specific phases within the period FC. S The frequency f is obtained by linearly interpolating the source frequencies of at least two specific phases. The high frequency power supply 31 generates a source frequency f at each of the phases between the first phase and the first specific phase and the phase between the last specific phase and the last phase in the cycle FC. S For example, when a period FC is rotated, the source frequency f S Interpolation is performed to ensure continuity or linearity of the

[0033] The plasma processing apparatus 1 may further include a sensor 35 for determining the degree of reflection of the source high frequency power HF (see FIG. 3). The plasma processing apparatus 1 may further include an envelope detector 36 and an AD converter (analog-to-digital converter) 37. The plasma processing apparatus 1 may further include an envelope detector 38 and an AD converter (analog-to-digital converter) 39.

[0034] The sensor 35 may include a directional coupler. The directional coupler branches a reflected wave of the source high frequency power HF from the load. The directional coupler inputs the branched reflected wave to the envelope detector 36. The envelope detector 36 detects the envelope of the input reflected wave. The AD converter 37 performs analog-to-digital conversion (AD conversion) on the envelope detected by the envelope detector 36. The sampling frequency in the AD converter 37 is set to the source frequency f S For example, the sampling frequency in the AD converter 37 may be 20 MHz or less.

[0035] The directional coupler may branch a traveling wave of the source high frequency power HF. The directional coupler may input the branched traveling wave to an envelope detector 38. The envelope detector 38 detects the envelope of the input traveling wave. The AD converter 39 performs analog-to-digital conversion (AD conversion) on the envelope detected by the envelope detector 38. The sampling frequency in the AD converter 39 is set to a value equal to the source frequency f S For example, the sampling frequency in the AD converter 39 may be 20 MHz or less.

[0036] The high frequency power source 31 determines the average value Prave of the power level of the reflected wave of the source high frequency power HF within the period FC by averaging the values sampled by the AD converter 37 within the period FC. The high frequency power source 31 may use the average value Prave as the degree of reflection within the period FC. Alternatively, the high frequency power source 31 may use the average value of the reflectivity within the period FC as the degree of reflection within the period FC. The reflectivity is the ratio of the value sampled by the AD converter 37 to the value sampled by the AD converter 39. The high frequency power source 31 may also use the degree of reflection of the source high frequency power HF calculated from measurements acquired by another sensor.

[0037] The high frequency power supply 31 and the bias power supply 32 set a phase difference θ between the period FC in which the source frequency is changed according to the initial frequency set and the waveform period CY so as to suppress the degree of reflection of the source high frequency power HF. The initial frequency set is set to a specific phase α a and specific phase α b The data set specifies an initial source frequency at at least two specific phases, such as: θ = 1 / 2 , ...

[0038] In one embodiment, the high frequency power supply 31 changes the phase difference θ between the period FC and the waveform period CY, and selects the phase difference θ that most effectively suppresses the degree of reflection of the source high frequency power HF. A The high frequency power supply 31 may determine the phase difference θ A may be set as the phase difference θ between the period FC and the waveform period CY. In one example, the high frequency power source 31 sets the phase difference θ between the period FC and the waveform period CY as the initial phase difference. Next, the high frequency power source 31 changes the phase difference θ. Specifically, the high frequency power source 31 sets the phase difference θ to a value obtained by adding a change amount Δθ to the previously used phase difference θ. Note that the high frequency power source 31 initially sets the change amount Δθ to a predetermined initial change amount. If the change in the phase difference θ reduces the degree of reflection of the source high frequency power HF, the high frequency power source 31 sets the phase difference θ to be used next to a value obtained by further adding the change amount Δθ to the current phase difference θ. On the other hand, if the change in the phase difference θ increases the degree of reflection of the source high frequency power HF, the high frequency power source 31 updates the change amount Δθ to the product of the current change amount Δθ and (−½), and sets the phase difference θ to be used next to a value obtained by adding the updated change amount Δθ to the current phase difference θ. The high frequency power supply 31 sets the phase difference θ when the absolute value of the change amount Δθ becomes smaller than a predetermined value to the phase difference θ that most effectively suppresses the degree of reflection of the source high frequency power HF. AOn the other hand, when the absolute value of the amount of change Δθ is equal to or greater than the predetermined value, the high frequency power supply 31 further changes the phase difference θ.

[0039] In another embodiment, the high frequency power supply 31 is a coincides with the first timing, and the specific phase α b The phase difference between the period FC and the waveform period CY may be set to a predetermined phase difference so that the period FC coincides with a second time point after the first time point. The first time point is the time point when the voltage on the substrate support 11 in response to the electrical bias EB switches from negative to positive. The second time point is the time point after the first time point and is within the period when the voltage on the substrate support 11 in response to the electrical bias EB changes from negative to positive.

[0040] After setting the phase difference between the period FC and the waveform period CY, the high frequency power supply 31 adjusts the source frequency f S Specifically, the high frequency power supply 31 adjusts the source frequency f within the period FC. S In the time series of a The maximum frequency and specific phase α b That is, the high frequency power supply 31 changes the minimum frequency at the source frequency f S The high frequency power source 31 widens and / or narrows the bandwidth between the maximum and minimum frequencies in the time series of periods FC. The high frequency power source 31 narrows and widens the bandwidth in the sequence of periods FC while narrowing and widening the bandwidth at a specific phase α that reduces or most suppresses the degree of reflection of the source high frequency power HF. a and specific phase α b Identify each source frequency.

[0041] The source frequency f of each phase within the period FC by expanding and / or reducing the bandwidth as described above S The adjustment of the source frequency f when the sequence of periods FC consists of several consecutive periods FC can be a sequential or pulse-to-pulse process. SThe adjustment of the source frequency f is a sequential process. On the other hand, when the pulses of the source high frequency power HF are periodically supplied, S This adjustment includes inter-pulse processing, which will be described later. First to third embodiments relating to the sequential processing and inter-pulse processing will be described below.

[0042] In the first embodiment, the period FC has at least two specific phases, namely, a specific phase α a and specific phase α b In this case, the high frequency power supply 31 may include only a specific phase α a and specific phase α b Source frequency f at a phase within the period FC other than S As shown in (b) of FIG. 5, the specific phase α a Maximum frequency and specific phase α a Alternatively, the frequency may be set to a frequency obtained by linear interpolation from the minimum frequency in the range.

[0043] In the second embodiment, the period FC may include at least three specific phases as the at least two specific phases. For example, the at least three specific phases may include a specific phase α a and specific phase α b In addition, a specific phase α c The specific phase α c is the specific phase α within the period FC b may be a phase after the specific phase α a and the specific phase α b The phase may be between

[0044] In the second embodiment, the high frequency power supply 31 controls the specific phase α a and specific phase α b The initial frequency is used as the source frequency for a specific phase other than . Note that the initial frequency is the specific phase α a and specific phase α bIn the second embodiment, the high frequency power supply 31 sets the source frequency f at a phase other than the at least three specific phases in the period FC in each of the sequential process and the inter-pulse process. S As the phases, frequencies linearly interpolated from the source frequencies at at least three specific phases are used.

[0045] In the second embodiment, the high frequency power supply 31 generates a specific phase α a and specific phase α b While fixing the initial frequency at a specific phase other than a and specific phase α b Each source frequency f S After that, the high frequency power supply 31 fixes the specific phase α a and specific phase α b Source frequency f of other specific phases within period FC other than S 6(b), the source frequency f of the other specific phase that reduces or most suppresses the degree of reflection of the source high frequency power HF is changed. S A specific phase α a and specific phase α b When there are multiple other specific phases other than the source frequency f of multiple other specific phases that reduce or most suppress the degree of reflection of the source high frequency power HF, S To identify the source frequency f S may be changed in sequence or may be changed simultaneously.

[0046] In the third embodiment, the high frequency power supply 31 generates a specific phase α a and specific phase α b Identify the frequency at other phases of the period FC other than phase α a and specific phase α bThe above-mentioned bandwidth expansion and / or narrowing is performed while being set by linear interpolation for each source frequency. Then, the high frequency power supply 31 outputs the specific phase α a and specific phase α b Each source frequency f S After that, the high frequency power supply 31 is turned on at a specific phase α a and specific phase α b At least one other phase other than (for example, the specific phase α in (c) of FIG. 5) d ) to reduce or most effectively suppress the reflection of the source high frequency power HF at the at least one other phase. S A specific phase α a and specific phase α b When there are multiple other specific phases other than the source frequency f of multiple other specific phases that reduce or most suppress the degree of reflection of the source high frequency power HF, S To identify the source frequency f S In the third embodiment, the high frequency power supply 31 changes the specific phase α a and specific phase α b Each source frequency f S After fixing, a specific phase α a , specific phase α b , and the source frequency f at a phase other than the at least one other phase S As a specific phase α a , specific phase α b , and a frequency linearly interpolated from the source frequency of each of the at least one other phase.

[0047] Reference is now made to FIG. 7, which shows examples of source RF power pulses and electrical bias pulses. In FIG. 7, "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 electric bias EB indicates that electric bias EB is being applied to the bias electrode, and "OFF" for electric bias EB indicates that electric bias EB is not being applied to the bias electrode.

[0048] 7, the high frequency power supply 31 may be configured to periodically supply pulses HFP of source high frequency power HF. Also, the bias power supply 32 may be configured to periodically supply pulses EBP of electrical bias EB. The pulses HFP and EBP are divided into a plurality of pulse periods PP, i.e., pulse periods PP1, PP2, . . . , PP K That is, the pulse HFP and the pulse EBP may be supplied simultaneously in a plurality of overlapping periods OP (i.e., overlapping periods OP1, OP2, . . . , OP K ) may be identical to each of the multiple pulse periods PP. Alternatively, the period in which the pulse HFP is supplied and the period in which the pulse EBP is supplied may partially overlap each other but be shifted from each other. In this case, each of the multiple overlapping periods OP is part of the period in which the pulse HFP is supplied and part of the period in which the pulse EBP is supplied.

[0049] Each of the multiple overlapping periods OP is a first period P a and the second period P b The first period P a is the period that includes the start of the corresponding overlap period OP. b is the first period P a The first period P is the period following the first period P and includes the end of the corresponding overlap period OP. a and the second period P bEach of the overlapping periods OP includes a repetition of the period FC and a repetition of the waveform period CY. That is, each of the multiple overlapping periods OP includes N periods FC, that is, periods FC1 to FC N In the following description, the period FC n is the n-th period FC among the multiple periods FC in each of the multiple overlapping periods OP.

[0050] Hereinafter, reference will be made to Figures 8(a) to 8(d), each of which is a diagram showing an example of a time series of the source frequency in a plasma processing apparatus according to one example embodiment.

[0051] Even when the pulses HFP and EBP are supplied periodically, the high frequency power supply 31 first sets the phase difference between the period FC and the waveform period CY as described above. When setting the phase difference between the period FC and the waveform period CY, as described above, the source frequency f S The time series of the first period P is set according to the initial frequency set. a Cycle FC n The initial frequency set applied to the second period P b The high frequency power supply 31 may be different from or the same as the initial frequency set applied to the period FC included in the second period P b The phase difference between the period FC and the waveform period CY may be determined solely depending on the degree of reflection at each period FC in the waveform.

[0052] After setting the phase difference between the period FC and the waveform period CY, the high frequency power supply 31 adjusts the source frequency f within the period FC so as to suppress the degree of reflection of the source high frequency power HF in the period FC. S When the pulses HFP and EBP are supplied periodically, the first period P of each of the multiple overlap periods OP is adjusted. a Cycle FC n is the period FC n Compose a sequence of

[0053] The high frequency power supply 31 is a Cycle FCn Source frequency f within S As a time series of the second period P b The source frequency f is specified by the initial frequency set used in S A time series of a frequency that is offset to the lower frequency side with respect to the time series of the first period P may be used. a Cycle FC n Source frequency f within S The time series of the second period P b Cycle FC n Source frequency f within S Alternatively, as shown in (a) and (b) of FIG. 8, the high frequency power supply 31 may generate a first period P of the multiple overlap periods OP. a Each cycle FC n In the sequence, the source frequency f S The time series of the above may be offset to the lower frequency side by different offset amounts to identify the frequency offset amount that most effectively suppresses the degree of reflection of the source high frequency power HF.

[0054] Thereafter, the high frequency power supply 31 generates a second period P b The above-described sequential process is applied to a plurality of consecutive periods FC in the overlapping periods OP. a The inter-pulse processing described above is applied to a number of consecutive periods FC in the period FC. n The inter-pulse processing is applied to the sequence of the first period P a Source frequency f within a period FC S The time series is adjusted, for example, as shown in FIG. 8(c) and / or FIG. 8(d).

[0055] As described above, according to the plasma processing apparatus 1, the source frequency f of the source high frequency power HF that suppresses the degree of reflection of the source high frequency power HF within the period FC having the same time length as the time length of the waveform period CY is STherefore, the degree of reflection of the source high frequency power HF is reduced in accordance with the change in the impedance of the load of the high frequency power supply 31 within the period of the electric bias EB. Furthermore, according to the plasma processing apparatus 1, the phase difference between the period FC and the waveform period CY is adjusted, and the specific phase α a The source frequency f S and the specific phase α b The source frequency f S By adjusting the bandwidth between S Therefore, according to the plasma processing apparatus 1, the source frequency f of the source high frequency power HF that suppresses the degree of reflection of the source high frequency power HF within the period FC can be set by a relatively simple process. S In one embodiment, the degree of reflection of the source high frequency power HF can be determined by analog-to-digital conversion with a relatively slow sampling rate.

[0056] A method for controlling a source frequency according to one exemplary embodiment will now be described with reference to Figure 9. Figure 9 is a flow diagram of a method for controlling a source frequency according to one exemplary embodiment. The method for controlling a source frequency shown in Figure 9 (hereinafter referred to as "method MT") begins with step STa.

[0057] In step STa, the phase difference between the period FC and the waveform period CY is set as described above.

[0058] In one embodiment, the method MT may include a step STb. The step STb may be performed when the pulse HFP and the pulse EBP are supplied periodically. In the step STb, a first period P a FC n Source frequency f within S The frequency offset amount for the time series is set as described above.

[0059] In the method MT, step STc is then performed. In step STc, a specific phase α a Source frequency f at S [α a] and specific phase α b Source frequency f at S [α b ], the degree of reflection of the source high frequency power HF is suppressed as a result of adjusting the bandwidth between the source frequency f S [α a ] and source frequency f S [α b For details of step STc, see the above description of sequential processing and inter-pulse processing.

[0060] The method MT may further comprise a step STd, which is carried out after step STc, in which the specific phase α a and specific phase α b Source frequency f at other specific phases other than S is changed to suppress the degree of reflection of the source high frequency power HF at the source frequency f S Alternatively, in step STd, the specific phase α a and specific phase α b The source frequency f at at least one other phase within the period FC other than S is changed to suppress the degree of reflection of the source high frequency power HF at the at least one other phase. S is identified.

[0061] Various exemplary embodiments included in the present disclosure are described below in [E1] to [E13].

[0062] [E1] a chamber; a substrate support disposed within the chamber; a radio frequency power source configured to generate source radio frequency power having a source frequency to generate a plasma from the gas in the chamber; a bias power supply configured to provide an electrical bias to the substrate support to attract ions from the plasma in the chamber, the electrical bias having a waveform period; and Equipped with the high frequency power supply is configured to set the time series of the source frequency within a frequency adjustment period having a time length equal to the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at a phase other than at least two specific phases including the first specific phase and the second specific phase; the high frequency power supply and the bias power supply are configured to set a phase difference between the frequency adjustment period, in which the source frequency is changed according to an initial frequency set that specifies an initial source frequency at the at least two specific phases, and the waveform period, so as to suppress a degree of reflection of the source high frequency power; the high frequency power supply is configured to, after setting the phase difference, specify the source frequency at the first specific phase and the source frequency at the second specific phase that suppress a degree of reflection of the source high frequency power, while changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other in the time series of the source frequency within the frequency adjustment period. Plasma processing equipment.

[0063] [E2] The plasma processing apparatus described in E1, wherein the high-frequency power supply is configured to identify the phase difference that most suppresses the degree of reflection of the source high-frequency power while changing the phase difference, and set the identified phase difference as the phase difference between the frequency adjustment period and the waveform period.

[0064] [E3] The plasma processing apparatus of E1, wherein the phase difference is set so that a first timing at which the voltage at the substrate support part in response to the electrical bias switches from negative to positive coincides with the first specific phase, and the second specific phase coincides with a second timing after the first timing at which the voltage at the substrate support part in response to the electrical bias changes from negative to positive.

[0065] [E4] The plasma processing apparatus according to any one of E1 to E3, wherein the high-frequency power supply is configured to set the source frequency at phases other than the first specific phase and the second specific phase within the frequency adjustment period to a frequency linearly interpolated from the maximum frequency at the first specific phase and the minimum frequency at the second specific phase.

[0066] [E5] the at least two specific phases include at least three specific phases, The high frequency power source is using an initial frequency as the source frequency at specific phases other than the first specific phase and the second specific phase among the at least three specific phases, and using a frequency linearly interpolated from the source frequency at the at least three specific phases as the source frequency at phases other than the at least three specific phases within the frequency adjustment period; after fixing the source frequency at the first specific phase and the source frequency at the second specific phase at respective frequencies specified by changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in mutually opposite directions, changing the source frequency at specific phases other than the first specific phase and the second specific phase among the at least three specific phases so as to reduce a degree of reflection of the source high frequency power; The plasma processing apparatus according to any one of E1 to E3, configured as described above.

[0067] [E6] The high frequency power source is setting the source frequency at phases other than the first specific phase and the second specific phase within the frequency adjustment period to a frequency linearly interpolated from the maximum frequency at the first specific phase and the minimum frequency at the second specific phase; fixing the source frequency at the first specific phase and the source frequency at the second specific phase at respective frequencies specified by changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other, and then changing the source frequency at phases other than the first specific phase and the second specific phase within the frequency adjustment period so as to reduce a degree of reflection of the source high frequency power; The plasma processing apparatus according to any one of E1 to E3, configured as described above.

[0068] [E7] The plasma processing apparatus includes: a directional coupler connected between the high frequency power supply and a load of the high frequency power supply; an envelope detection circuit that detects an envelope of a reflected wave of the source high frequency power output from the directional coupler; an AD conversion circuit that performs analog-to-digital conversion of the envelope; Equipped with The plasma processing apparatus according to any one of E1 to E6, wherein the high-frequency power supply is configured to determine the degree of reflection based on an average value within the frequency adjustment period of the amplitude of the envelope digitized by the AD conversion circuit.

[0069] [E8] The plasma processing apparatus according to E7, wherein the sampling frequency of the AD conversion circuit is lower than the source frequency of the source high frequency power.

[0070] [E9] the radio frequency power source is configured to periodically provide pulses of the source radio frequency power; the bias power supply is configured to periodically provide pulses of the electrical bias; the period during which the pulse of the source radio frequency power and the pulse of the electrical bias are simultaneously supplied includes a first period and a second period following the first period; the high frequency power supply is configured to use, as the time series of source frequencies in the frequency adjustment cycle within the first time period, a time series of frequencies that is offset toward a lower frequency direction relative to the time series of source frequencies specified by the initial frequency set used in the second time period. The plasma processing apparatus according to any one of E1 to E8.

[0071] [E10] The plasma processing apparatus described in E9, wherein the high-frequency power supply is configured to change the phase difference and identify the phase difference that best suppresses the degree of reflection of the source high-frequency power based only on the degree of reflection during the second period.

[0072] [E11] The plasma processing apparatus of any one of E1 to E10, wherein the electrical bias is a bias high frequency power having a bias frequency that is the inverse of the time length of the waveform period, or includes a voltage pulse that is supplied periodically at a time interval equal to the time length of the waveform period.

[0073] [E12] a radio frequency power source configured to generate a source radio frequency power having a source frequency to generate a plasma from the gas in a chamber of the plasma processing apparatus; a bias power supply configured to provide an electrical bias to a substrate support in the chamber to attract ions from the plasma in the chamber, the electrical bias having a waveform period; Equipped with the high frequency power supply is configured to set the time series of the source frequency within a frequency adjustment period having a time length equal to the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at a phase other than at least two specific phases including the first specific phase and the second specific phase; the high frequency power supply and the bias power supply are configured to set a phase difference between the frequency adjustment period, in which the source frequency is changed according to an initial frequency set that specifies an initial source frequency at the at least two specific phases, and the waveform period, so as to suppress a degree of reflection of the source high frequency power; the high frequency power supply is configured to, after setting the phase difference, specify the source frequency at the first specific phase and the source frequency at the second specific phase that suppress a degree of reflection of the source high frequency power, while changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other in the time series of the source frequency within the frequency adjustment period. Power supply system.

[0074] [E13] 1. A method for controlling a source frequency, comprising: (a) providing source radio frequency power having a source frequency from a radio frequency power source to generate plasma from a gas in a chamber of a plasma processing device; (b) applying an electrical bias from a bias power supply to a substrate support in the chamber to attract ions from a plasma in the chamber, the electrical bias having a waveform period; Including, In the step (a), the high frequency power supply sets the time series of the source frequency within a frequency adjustment period having the same time length as the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at a phase other than at least two specific phases including the first specific phase and the second specific phase; The method comprises: (c) setting a phase difference between the frequency adjustment period and the waveform period during which the source frequency is changed according to an initial frequency set that specifies an initial source frequency at the at least two specific phases, so as to suppress a degree of reflection of the source high frequency power; (d) after setting the phase difference, specifying the source frequency at the first specific phase and the source frequency at the second specific phase that suppress a degree of reflection of the source high frequency power while changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other in the time series of the source frequency within the frequency adjustment period; Further comprising: A method for controlling the source frequency.

[0075] 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]

[0076] 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 generate source radio frequency power having a source frequency to generate a plasma from the gas in the chamber; a bias power supply configured to provide an electrical bias to the substrate support to attract ions from the plasma in the chamber, the electrical bias having a waveform period; and Equipped with the high frequency power supply is configured to set the time series of the source frequency within a frequency adjustment period having a time length equal to the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at a phase other than at least two specific phases including the first specific phase and the second specific phase; the high frequency power supply and the bias power supply are configured to set a phase difference between the frequency adjustment period, in which the source frequency is changed according to an initial frequency set that specifies an initial source frequency at the at least two specific phases, and the waveform period, so as to suppress a degree of reflection of the source high frequency power; the high frequency power supply is configured to, after setting the phase difference, specify the source frequency at the first specific phase and the source frequency at the second specific phase that suppress a degree of reflection of the source high frequency power, while changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other in the time series of the source frequency within the frequency adjustment period. Plasma processing equipment.

2. 2. The plasma processing apparatus according to claim 1, wherein the high frequency power supply is configured to change the phase difference to identify the phase difference that most effectively suppresses the degree of reflection of the source high frequency power, and to set the identified phase difference as the phase difference between the frequency adjustment period and the waveform period.

3. 2. The plasma processing apparatus of claim 1, wherein the phase difference is set so that a first timing at which a voltage at the substrate support part in response to the electrical bias switches from negative to positive coincides with the first specific phase, and the second specific phase coincides with a second timing after the first timing at which the voltage at the substrate support part in response to the electrical bias changes from negative to positive.

4. 4. The plasma processing apparatus according to claim 1, wherein the high frequency power supply is configured to set the source frequency at phases other than the first specific phase and the second specific phase within the frequency adjustment period to a frequency linearly interpolated from the maximum frequency at the first specific phase and the minimum frequency at the second specific phase.

5. the at least two specific phases include at least three specific phases, The high frequency power source is an initial frequency is used as the source frequency at specific phases other than the first specific phase and the second specific phase among the at least three specific phases, and a frequency linearly interpolated from the source frequency at the at least three specific phases is used as the source frequency at phases other than the at least three specific phases within the frequency adjustment period; after fixing the source frequency at the first specific phase and the source frequency at the second specific phase at respective frequencies specified by changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in mutually opposite directions, changing the source frequency at specific phases other than the first specific phase and the second specific phase among the at least three specific phases so as to reduce a degree of reflection of the source high frequency power; 4. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is configured as described above.

6. The high frequency power source is setting the source frequency at phases other than the first specific phase and the second specific phase within the frequency adjustment period to a frequency linearly interpolated from the maximum frequency at the first specific phase and the minimum frequency at the second specific phase; after fixing the source frequency at the first specific phase and the source frequency at the second specific phase at respective frequencies specified by changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other, changing the source frequency at phases other than the first specific phase and the second specific phase within the frequency adjustment period so as to reduce a degree of reflection of the source high frequency power; 4. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is configured as described above.

7. The plasma processing apparatus includes: a directional coupler connected between the high frequency power supply and a load of the high frequency power supply; an envelope detection circuit that detects an envelope of a reflected wave of the source high frequency power output from the directional coupler; an AD conversion circuit for performing analog-to-digital conversion of the envelope; Equipped with The plasma processing apparatus according to any one of claims 1 to 3, wherein the high frequency power supply is configured to determine the degree of reflection based on an average value within the frequency adjustment period of the amplitude of the envelope digitized by the AD conversion circuit.

8. 8. The plasma processing apparatus according to claim 7, wherein the sampling frequency of the AD conversion circuit is lower than the source frequency of the source high frequency power.

9. the radio frequency power source is configured to periodically provide pulses of the source radio frequency power; the bias power supply is configured to periodically provide pulses of the electrical bias; the period during which the pulse of the source radio frequency power and the pulse of the electrical bias are simultaneously supplied includes a first period and a second period following the first period; the high frequency power supply is configured to use, as the time series of the source frequencies in the frequency adjustment cycle within the first time period, a time series of frequencies that is offset in a lower frequency direction relative to the time series of the source frequencies specified by the initial frequency set used in the second time period. The plasma processing apparatus according to any one of claims 1 to 3.

10. 10. The plasma processing apparatus of claim 9, wherein the high frequency power supply is configured to change the phase difference and identify the phase difference that most effectively suppresses the degree of reflection of the source high frequency power, based only on the degree of reflection during the second period.

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

12. a radio frequency power source configured to generate a source radio frequency power having a source frequency to generate a plasma from the gas in a chamber of the plasma processing apparatus; a bias power supply configured to provide an electrical bias to a substrate support in the chamber to attract ions from the plasma in the chamber, the electrical bias having a waveform period; Equipped with the high frequency power supply is configured to set the time series of the source frequency within a frequency adjustment period having a time length equal to the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at a phase other than at least two specific phases including the first specific phase and the second specific phase; the high frequency power supply and the bias power supply are configured to set a phase difference between the frequency adjustment period, in which the source frequency is changed according to an initial frequency set that specifies an initial source frequency at the at least two specific phases, and the waveform period, so as to suppress a degree of reflection of the source high frequency power; the high frequency power supply is configured to, after setting the phase difference, specify the source frequency at the first specific phase and the source frequency at the second specific phase that suppress a degree of reflection of the source high frequency power, while changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other in the time series of the source frequency within the frequency adjustment period. Power supply system.

13. 1. A method for controlling a source frequency, comprising: (a) providing source radio frequency power having a source frequency from a radio frequency power source to generate a plasma from a gas in a chamber of a plasma processing apparatus; (b) applying an electrical bias from a bias power supply to a substrate support in the chamber to attract ions from a plasma in the chamber, the electrical bias having a waveform period; Including, In the method (a), the high frequency power supply sets the time series of the source frequency within a frequency adjustment period having the same time length as the time length of the waveform period to a maximum frequency at a first specific phase, a minimum frequency at a second specific phase, and an interpolated frequency at a phase other than at least two specific phases including the first specific phase and the second specific phase; The method comprises: (c) setting a phase difference between the frequency adjustment period and the waveform period during which the source frequency is changed according to an initial frequency set that specifies an initial source frequency at the at least two specific phases, so as to suppress a degree of reflection of the source high frequency power; (d) after setting the phase difference, specifying the source frequency at the first specific phase and the source frequency at the second specific phase that suppress a degree of reflection of the source high frequency power while changing the maximum frequency at the first specific phase and the minimum frequency at the second specific phase in directions opposite to each other in the time series of the source frequency within the frequency adjustment period; Further comprising: A method for controlling the source frequency.

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