Plasma processing apparatus and method of controlling frequency of source high frequency power

Abstract

A plasma processing apparatus disclosed in the present invention has a chamber, a substrate support section, a high-frequency power source, and a bias power source. The high-frequency power source generates source high-frequency power for generating plasma in the chamber. The bias power source applies a pulse of bias energy to a bias electrode in each of a plurality of pulse periods. The high-frequency power source sets a source frequency of the source high-frequency power in each of a plurality of phase periods in each of a plurality of overlap periods overlapping the plurality of pulse periods, respectively, in accordance with a change in a degree of reflection. The degree of reflection is determined by using mutually different source frequencies in the same phase period within two or more preceding overlap periods.

Description

Technical Field

[0001] The exemplary embodiments of the present invention relate to a plasma processing apparatus and a method for controlling the source frequency of a high-frequency power source. Background Technology

[0002] Plasma processing apparatuses are used in the plasma processing of substrates. To introduce ions from the plasma generated within a chamber into the substrate, the plasma processing apparatus uses bias high-frequency power. Patent Document 1 below discloses a plasma processing apparatus that modulates the power level and frequency of the bias high-frequency power.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-246091 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] This invention provides a technique for reducing the reflection of high-frequency power sources in a plasma processing device.

[0008] Methods for solving problems

[0009] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a high-frequency power supply, and a bias power supply. The substrate support has bias electrodes disposed within the chamber. The high-frequency power supply is configured to generate source high-frequency power for generating plasma within the chamber. The bias power supply is configured to apply pulses of bias energy to bias electrodes in each of a plurality of pulse periods. The bias power supply is configured to periodically apply bias energy having a waveform period to bias electrodes in each of the plurality of pulse periods. The high-frequency power supply is configured to set the source frequency of the source high-frequency power in each of the plurality of phase periods of the waveform period of bias energy included in each of the plurality of overlapping periods. The plurality of overlapping periods overlap with the plurality of pulse periods. The high-frequency power supply is configured to perform inter-pulse feedback. The inter-pulse feedback includes adjusting the source frequency f(k, m, n) according to changes in the degree of reflection of the source high-frequency power. f(k, m, n) is the source frequency in the nth phase period of the mth waveform period within the kth overlapping period of the plurality of overlapping periods. The variation in the degree of reflection is determined by using mutually different source frequencies during the nth phase period within the mth waveform period of each of the two or more overlapping periods preceding the kth overlapping period.

[0010] Invention Effects

[0011] According to one exemplary embodiment, the degree of reflection of source high-frequency power can be reduced in a plasma processing apparatus. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating an exemplary embodiment of a plasma processing apparatus.

[0013] Figure 2 This is a schematic diagram illustrating an exemplary embodiment of a plasma processing apparatus.

[0014] Figure 3 (a) and Figure 3 (b) are timing diagrams of an example of source high-frequency power and bias energy, respectively.

[0015] Figure 4 (a) and Figure 4 (b) are timing diagrams of an example of source high-frequency power and bias energy, respectively.

[0016] Figure 5 This is a timing diagram of an example of bias energy versus the source frequency of the source high-frequency power.

[0017] Figure 6 This is another example of a timing diagram showing the bias energy and the source frequency of the source high-frequency power.

[0018] Figure 7 This is a timing diagram for another example of bias energy.

[0019] Figure 8 This is a timing diagram of an example of bias energy versus the source frequency of the source high-frequency power.

[0020] Figure 9 This is a flowchart illustrating an exemplary implementation of a method for controlling the source frequency of a high-frequency power source.

[0021] Figure 10 (a)~ Figure 10 (d) are timing diagrams for another example of bias energy. Detailed Implementation

[0022] The following describes various illustrative implementation methods.

[0023] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a high-frequency power supply, and a bias power supply. The substrate support has bias electrodes disposed within the chamber. The high-frequency power supply is configured to generate source high-frequency power for generating plasma within the chamber. The bias power supply is configured to apply pulses of bias energy to the bias electrodes in each of a plurality of pulse periods. The bias power supply is configured to periodically apply bias energy having a waveform period to the bias electrodes in each of the plurality of pulse periods. The high-frequency power supply is configured to set the source frequency of the source high-frequency power in each of the plurality of phase periods of the waveform period of the bias energy contained in each of the plurality of overlapping periods. The plurality of overlapping periods overlap with the plurality of pulse periods. The high-frequency power supply is configured to perform inter-pulse feedback. The inter-pulse feedback includes adjusting the source frequency f(k, m, n) according to changes in the degree of reflection of the source high-frequency power. f(k, m, n) is the source frequency in the nth phase period of the mth waveform period within the kth overlapping period of the plurality of overlapping periods. The variation in the degree of reflection is determined by using mutually different source frequencies during the nth phase period within the mth waveform period of each of the two or more overlapping periods preceding the kth overlapping period.

[0024] By using different source frequencies during the same phase period within the same waveform cycle in two or more overlapping periods, the relationship between the change in source frequency (frequency shift) and the change in the degree of reflection of the source high-frequency power can be determined. Therefore, according to the above embodiment, the source frequency used during the nth phase period within the mth waveform cycle in the kth overlapping period can be adjusted to reduce the degree of reflection based on the change in the degree of reflection. Furthermore, according to the above embodiment, the degree of reflection can be rapidly reduced in each of the multiple waveform cycles within the multiple overlapping periods.

[0025] In one exemplary implementation, two or more overlapping periods may include the (k-K1)th overlapping period and the (k-K2)th overlapping period. Here, K1 and K2 are natural numbers that satisfy K1>K2.

[0026] In one exemplary embodiment, inter-pulse feedback may include applying a frequency shift from one of the source frequencies f(k-K1, m, n) to the source frequency f(k-K2, m, n). The frequency shift is either a decrease or an increase in frequency. If the reflection level is reduced by using f(k-K2, m, n) obtained through the frequency shift, inter-pulse feedback may set f(k, m, n) to a frequency with a frequency shift relative to f(k-K2, m, n). If the reflection level is increased by using f(k, m, n) obtained through the frequency shift, inter-pulse feedback may set the source frequency f(k+K3, m, n) to an intermediate frequency. The intermediate frequency is the frequency between f(k-K2, m, n) and the source frequency f(k, m, n). Furthermore, K3 is a natural number.

[0027] In one exemplary implementation, there exists a situation where the aforementioned intermediate frequency is used during the nth phase period of the mth waveform cycle within the (k+K3)th overlap period, and the reflection level is greater than a threshold. In this case, inter-pulse feedback can set the source frequency f(k+K4, m, n) to a frequency with a frequency shift relative to the intermediate frequency of the other. In this case, the other frequency shift has an absolute value greater than the absolute value of the frequency shift of the first frequency. Furthermore, K4 is a natural number satisfying K4>K3.

[0028] In one exemplary implementation, the absolute value of the amount of frequency shift used to obtain f(k, m, n) can be greater than the absolute value of the amount of frequency shift used to obtain f(k-K2, m, n).

[0029] In one exemplary implementation, inter-pulse feedback may include applying a frequency shift from one of f(k-K1, m, n) to f(k-K2, m, n). The frequency shift is either a decrease or an increase in frequency. If the degree of reflection increases when f(k-K2, m, n) is obtained by using the frequency shift of one, inter-pulse feedback may set f(k, m, n) to a frequency with the other frequency shift relative to f(k-K2, m, n).

[0030] In one exemplary embodiment, the bias energy can be a bias high-frequency power having a bias frequency that is the reciprocal of the duration of the waveform period. The bias energy can include voltage pulses applied to the bias electrodes in each of a plurality of waveform periods having a duration that is the reciprocal of the bias frequency.

[0031] In one exemplary implementation, the multiple overlapping periods include the first to the Kth. a There are overlapping periods. Here, K a It is a natural number greater than 2. High-frequency power supplies can operate during the overlap period OP(1)~OP(K).a The waveform periods CY(1) to CY(M) contained in each of them a In each of the multiple phase periods, initial processing is performed to set the source frequency in each of the multiple phase periods to multiple frequencies contained in a pre-prepared frequency set. Here, OP(k) is the k-th overlapping period among the multiple overlapping periods. CY(m) is the m-th waveform period in each overlapping period. The high-frequency power supply can be used during the overlapping periods OP(1) to OP(k). a In each of the waveform periods CY(M) a Intra-pulse feedback is performed in the waveform period following the initial pulse. Intra-pulse feedback involves adjusting the source frequency f(k, m, n) based on the changes in the degree of reflection of the source high-frequency power during the nth phase of each of two or more waveform periods preceding the waveform period CY(m) in each overlapping period.

[0032] In one exemplary implementation, the plurality of overlapping periods may further include an overlapping period OP(K). a +1) ~ Overlapping period OP(K) b Here, K b Yes (K) a Natural numbers greater than or equal to +1. High-frequency power supplies can operate during overlap periods of OP(K). a +1) ~ Overlapping period OP(K) b The waveform periods CY(1) and CY(M) contained in each waveform are respectively b1 The above initial processing is performed in each of the ) . In addition, the high-frequency power supply can be used during the overlap period OP(K a +1) ~ Overlapping period OP(K) b The waveform period CY(M) contained in each b1 +1) ~ Waveform period CY(M) b2 The aforementioned inter-pulse feedback can be performed during the overlap period (OP(K)). Furthermore, the high-frequency power supply can perform this inter-pulse feedback during the overlap period (OP(K)). a +1) ~ Overlapping period OP(K) b In each of the waveform periods CY(M) b2 Then, the above-mentioned intra-pulse feedback is performed. Here, M b1 and M a It can satisfy M b1 <M a .

[0033] In one exemplary implementation, the high-frequency power supply can OP(K) during the overlap period. b +1) ~ The waveform period CY(1) contained in each of the final overlapping periods ~ the waveform period CY(M) c The aforementioned inter-pulse feedback can be performed during the overlap period (OP(K)). Furthermore, the high-frequency power supply can perform this inter-pulse feedback during the overlap period (OP(K)). b+1) ~ During the final overlap period, in each of the waveform periods CY(M) c Then, the above-mentioned intra-pulse feedback is performed.

[0034] In one exemplary embodiment, the high-frequency power supply may be configured such that, during at least one overlap period from the second to the last overlap period among a plurality of overlap periods, the source frequency in the nth phase period of the waveform period in which the initial intra-pulse feedback is applied in a plurality of waveform cycles is set to the source frequency of the nth phase period in the last waveform period among a plurality of waveform cycles included in the preceding overlap period of the at least one overlap period, or the average of the source frequencies of the nth phase periods of two or more waveform cycles including the last waveform period.

[0035] In one exemplary embodiment, the high-frequency power supply may be configured to terminate the initial processing when a monitoring value reflecting the degree of reflection enters a specified range during the initial processing described above.

[0036] In another exemplary embodiment, a method for controlling the source frequency of a source high-frequency power is provided. The method includes the step (a): applying a pulse of bias energy to a bias electrode disposed within a cavity of a plasma processing apparatus during each of a plurality of pulse periods. The bias energy has a waveform period and is periodically applied to the bias electrode during each of the plurality of pulse periods. The method further includes the step of supplying source high-frequency power from a high-frequency power source to generate plasma within the cavity. The method further includes the step of setting the source frequency of the source high-frequency power during each of a plurality of phase periods within each of the plurality of waveform periods of the bias energy contained in each of the plurality of overlapping periods. The plurality of overlapping periods overlap with the plurality of pulse periods respectively. The source frequency f(k, m, n) is adjusted according to a change in the degree of reflection of the source high-frequency power. The change in the degree of reflection is determined by using mutually different source frequencies during the nth phase period within the mth waveform period of each of two or more overlapping periods preceding the kth overlapping period.

[0037] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts will be given the same reference numerals in each drawing.

[0038] Figure 1 and Figure 2 This is a diagram that schematically illustrates a plasma processing apparatus of an exemplary embodiment.

[0039] In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. Furthermore, the plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to the gas supply unit 20 (described later), and the gas outlet is connected to the exhaust system 40 (described later). The substrate support 11 is disposed within the plasma processing space and has a substrate support surface for supporting a substrate.

[0040] The plasma generation unit 12 is configured to generate plasma from at least one process gas supplied to the plasma processing space. The plasma generated in the plasma processing space can be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR), helicon wave plasma (HWP), or surface wave plasma (SWP), etc. Furthermore, various types of plasma generation units, including AC (alternating current) plasma generation units and DC (direct current) plasma generation units, can be used.

[0041] The control unit 2 processes computer-executable commands that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control various elements of the plasma processing apparatus 1, causing the various processes described herein to be performed. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may, for example, include a computer 2a. The computer 2a may, for example, include a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control actions based on a program stored in the storage unit 2a2. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read-Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or combinations thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0042] The following describes a configuration example of a capacitively coupled plasma processing apparatus 1, which is an example of a plasma processing apparatus 1. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. Furthermore, the plasma processing apparatus 1 includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a spray head 13. The substrate support 11 is disposed within the plasma processing chamber 10. The spray head 13 is disposed above the substrate support 11. In one embodiment, the spray head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the spray head 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The sidewall 10a is grounded. The spray head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0043] The substrate support portion 11 includes a body portion 111 and a ring assembly 112. The body portion 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W and an annular region (ring support surface) 111b for supporting the ring assembly 112. The annular region 111b of the body portion 111 surrounds the central region 111a of the body portion 111 when viewed from above. The substrate W is disposed on the central region 111a of the body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the body portion 111 such that it surrounds the substrate W on the central region 111a of the body portion 111. In one embodiment, the body portion 111 includes a base 111e and an electrostatic chuck 111c. The base 111e includes conductive components. The conductive components of the base 111e serve as a lower electrode. The electrostatic chuck 111c is disposed on the base 111e. The upper surface of the electrostatic chuck 111c has a substrate support surface 111a. The ring assembly 112 includes one or more annular components. At least one of the one or more annular components is an edge ring. Furthermore, although not shown in the figures, the substrate support 11 may include a temperature control module configured to adjust at least one of the electrostatic chuck 111c, the ring assembly 112, and the substrate W to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. Additionally, the substrate support 11 may include a heat transfer gas supply section configured to supply heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0044] The spray head 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The spray head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlets 13c. The process gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s through the gas diffusion chamber 13b and the plurality of gas inlets 13c. Furthermore, the spray head 13 includes a conductive component. The conductive component of the spray head 13 serves as an upper electrode. In addition to the spray head 13, the gas inlet may also include one or more side gas injectors (SGIs) mounted on one or more openings formed in the sidewall 10a.

[0045] The gas supply unit 20 may include one or more gas sources 21 and at least one or more flow controllers 22. In one embodiment, the gas supply unit 20 is configured to supply one or more processing gases from their respective gas sources 21 to the spray head 13 via their respective flow controllers 22. Each flow controller 22 may, for example, include a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulation devices for modulating or pulsedizing the flow rate of the one or more processing gases.

[0046] The exhaust system 40 may, for example, be connected to a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space 10s is adjusted via the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0047] The plasma processing apparatus 1 also includes a high-frequency power supply 31 and a bias power supply 32. The plasma processing apparatus 1 may also include a sensor 31s and a control unit 30c.

[0048] The high-frequency power supply 31 is configured to generate source high-frequency power RF for generating plasma within the chamber (plasma processing chamber 10). The source high-frequency power RF has, for example, a source frequency of 13 MHz or higher and 150 MHz or lower. In one embodiment, the high-frequency power supply 31 may include a high-frequency signal generator 31g and an amplifier 31a. The high-frequency signal generator 31g generates a high-frequency signal. The amplifier 31a generates the source high-frequency power RF by amplifying the high-frequency signal input from the high-frequency signal generator 31g and outputs the source high-frequency power RF. Furthermore, the high-frequency signal generator 31g may be constructed from a programmable processor or a programmable logic device such as an FPGA. Additionally, a D / A converter may be connected between the high-frequency signal generator 31g and the amplifier 31a.

[0049] The high-frequency power supply 31 is connected to the high-frequency electrode via a matching adapter 31m. In one embodiment, the base 111e constitutes the high-frequency electrode. In another embodiment, the high-frequency electrode may be an electrode disposed in an electrostatic chuck 111c. The high-frequency electrode may be an electrode shared with the bias electrode described later. Alternatively, the high-frequency electrode may be an upper electrode. The matching adapter 31m includes a matching circuit. The matching circuit of the matching adapter 31m has a variable impedance. The matching circuit of the matching adapter 31m is controlled by a control unit 30c. The impedance of the matching circuit of the matching adapter 31m is adjusted to match the impedance on the load side of the high-frequency power supply 31 with the output impedance of the high-frequency power supply 31.

[0050] Sensor 31s is configured to output the reflected wave of the source high-frequency power RF returned from the load of the high-frequency power supply 31 to the control unit 30c. Sensor 31s can be connected between the high-frequency power supply 31 and the matching unit 31m. Sensor 31s can also be connected between the matching unit 31m and the high-frequency electrode. For example, sensor 31s can be connected between the point where the electrical path extending from the matching unit 31m towards the bias electrode and the electrical path extending from the matching unit 32m towards the bias electrode (described later) converge and the bias electrode. Alternatively, sensor 31s can also be connected between this convergence point and the matching unit 31m. Sensor 31s includes, for example, a directional coupler. The directional coupler outputs the reflected wave returned from the load of the high-frequency power supply 31. The reflected wave output from the directional coupler is converted into a digital signal by an A / D converter, and the digitized reflected wave is utilized in the control unit 30c. Alternatively, sensor 31s can be a sensor separate from the matching unit 31m, or it can be part of the matching unit 31m.

[0051] The bias power supply 32 is electrically connected to the bias electrode. In one embodiment, the base 111e constitutes a bias electrode. In another embodiment, the bias electrode may be an electrode disposed in the electrostatic chuck 111c. The bias power supply 32 is configured to apply a pulse BEP of bias energy BE to the bias electrode during each of the plurality of pulse periods PP. The bias power supply 32 can determine the timing of each of the plurality of pulse periods PP by means of a signal applied from the pulse controller 34. Additionally, the control unit 2 can be used as the pulse controller 34.

[0052] Here, refer to Figure 3 of (a), Figure 3 (b) Figure 4 (a) and Figure 4 (b) Figure 3 of (a), Figure 3 (b) Figure 4 (a) and Figure 4(b) are timing diagrams for an example of source high-frequency power RF and bias energy BE. In these diagrams, "ON" for source high-frequency power RF indicates that source high-frequency power RF is supplied, and "OFF" for source high-frequency power RF indicates that the supply of source high-frequency power RF is stopped. Furthermore, in these diagrams, "ON" for bias energy BE indicates that bias energy BE is applied to the bias electrode, and "OFF" for bias energy BE indicates that bias energy BE is not applied to the bias electrode. Additionally, in these diagrams, "HIGH" for bias energy BE indicates that a level of bias energy BE higher than that shown by "LOW" is applied to the bias electrode.

[0053] Multiple pulse periods PP occur sequentially in time. These multiple pulse periods PP can occur sequentially at time intervals (periods) equal to the reciprocal of the pulse frequency. Furthermore, in the following description, pulse period PP(k) represents the k-th pulse period among the multiple pulse periods PP. That is, pulse period PP(k) represents any pulse period among the multiple pulse periods PP. The pulse frequency is lower than the bias frequency described later, for example, a frequency of 1 kHz or higher and 100 kHz or lower. As described above, the pulse BEP of the bias energy BE is applied to the bias electrode in each of the multiple pulse periods PP. During periods other than the multiple pulse periods PP, the bias energy BE may not be applied to the bias electrode. Alternatively, during periods other than the multiple pulse periods PP, a bias energy BE with a level lower than the level of the bias energy BE in the multiple pulse periods PP may be applied to the bias electrode.

[0054] like Figure 3 As shown in (a), the source high-frequency power RF can be used as a continuous wave supply. Figure 3 In the example shown in (a), the multiple overlapping periods of the high-frequency power RF supplied by PP during multiple pulse periods coincide with the multiple pulse periods of PP.

[0055] Or, such as Figure 3 (b) Figure 4 (a) and Figure 4 As shown in (b), pulses can be supplied to the source high-frequency power RF. The high-frequency power supply 31 can determine the timing of the pulses supplied to the source high-frequency power RF by a signal applied from the pulse controller 34. Figure 3 As shown in (b), pulses of high-frequency power RF can be supplied to the source during each of the multiple periods that coincide with the multiple pulse periods PP. Figure 3 In the example shown in (b), the multiple overlapping periods OP of the high-frequency power RF supplied by PP during multiple pulse periods coincide with the multiple pulse periods of PP. Figure 4 (a) and Figure 4As shown in (b), pulses of high-frequency power RF can be supplied in each of the multiple periods that partially overlap with the multiple pulse periods PP. Figure 4 (a) and Figure 4 In the examples shown in (b), each of the multiple overlapping periods OP of the high-frequency power RF supplied by the PP during the multiple pulse periods is a portion of the corresponding pulse period PP among the multiple pulse periods PP. Furthermore, in the following description, the overlapping period OP(k) represents the k-th overlapping period among the multiple overlapping periods OP. That is, the overlapping period OP(k) represents any overlapping period among the multiple overlapping periods OP.

[0056] The bias energy BE is applied to the bias electrode during each of the multiple waveform periods CY in the multiple pulse periods PP. That is, the bias energy BE is periodically applied to the bias electrode during each of the multiple pulse periods PP. Each of the multiple waveform periods CY is defined by a bias frequency. The bias frequency is, for example, a frequency of 50 kHz or higher and 27 MHz or lower. The duration of each of the multiple waveform periods CY is the reciprocal of the bias frequency. The multiple waveform periods CY appear sequentially in time. In the following explanation, the waveform period CY(m) represents the m-th waveform period among the multiple waveform periods CY in the multiple overlapping periods OP. Furthermore, the waveform period CY(k,m) represents the m-th waveform period within the k-th overlapping period. That is, the waveform period CY(m) represents any waveform period among the multiple waveform periods CY.

[0057] Here, refer to Figure 5 and Figure 6 . Figure 5 This is a timing diagram of an example of bias energy and the source frequency of the source high-frequency power. Figure 6 This is another example of a timing diagram for bias energy and the source frequency of the source high-frequency power. For example... Figure 5 and Figure 6 As shown, in one embodiment, the bias energy BE can be a bias high-frequency power having a bias frequency. The bias high-frequency power has a sinusoidal waveform, one period of which is the waveform period CY. In this case, as... Figure 2 As shown, the bias power supply 32 may include a high-frequency signal generator 32g and an amplifier 32a. The high-frequency signal generator 32g generates a high-frequency signal. The amplifier 32a amplifies the high-frequency signal input from the high-frequency signal generator 32g to generate bias high-frequency power, which is then supplied to the bias electrode as bias energy BE. Furthermore, the high-frequency signal generator 32g may be constructed from a programmable processor or a programmable logic device such as an FPGA. Additionally, a D / A converter may be connected between the high-frequency signal generator 32g and the amplifier 32a.

[0058] When the bias energy BE is a bias high-frequency power supply, the bias power supply 32 is connected to the bias electrode via a matching converter 32m. The matching converter 32m includes a matching circuit. The matching circuit of the matching converter 32m has a variable impedance. The matching circuit of the matching converter 32m is controlled by the control unit 30c. The impedance of the matching circuit of the matching converter 32m is adjusted to match the impedance on the load side of the bias power supply 32 with the output impedance of the bias power supply 32.

[0059] Figure 7 This is a timing diagram for another example of bias energy. For example... Figure 7 As shown, in another embodiment, the bias energy BE may include pulses of voltage applied to the bias electrode at various times of a plurality of waveform periods CY. The pulses of voltage used as the bias energy BE may be as follows: Figure 7 The example shown is a negative voltage pulse, but it can also be a pulse of other voltages. The voltage pulse used as the bias energy BE can have waveforms such as triangular waves or rectangular waves. The voltage pulse can also have any other arbitrary pulse waveform. When using a voltage pulse as the bias energy BE, instead of... Figure 2 The matching unit 32m shown can be connected between the bias power supply 32 and the bias electrode to a filter that cuts off the high-frequency power RF source.

[0060] The bias power supply 32 is synchronized with the high-frequency power supply 31. The synchronization signal used for this purpose can be applied from the bias power supply 32 to the high-frequency power supply 31. Alternatively, the synchronization signal can be applied from the high-frequency power supply 31 to the bias power supply 32. Alternatively, the synchronization signal can be applied to both the high-frequency power supply 31 and the bias power supply 32 from another device such as the control unit 30c.

[0061] The control unit 30c is configured to control the high-frequency power supply 31. The control unit 30c can be a processor such as a CPU. The control unit 30c can be part of the matching unit 31m, part of the high-frequency power supply 31, or a control unit separate from the matching unit 31m and the high-frequency power supply 31. Alternatively, the control unit 2 can also serve as the control unit 30c.

[0062] The control unit 30c is configured to set the source frequency of the source high-frequency power RF in each of the multiple phase periods SP within each of the multiple waveform periods CY included in each of the multiple overlapping periods OP. The source frequency of the source high-frequency power RF supplied during periods other than the multiple overlapping periods OP can be set using a time series of frequencies registered in a pre-prepared table. Hereinafter, an embodiment of the control unit 30c setting the source frequency will be described. However, when the control unit 30c is part of the high-frequency power supply 31, the high-frequency power supply 31 can set the source frequency.

[0063] [Setting the source frequency of the source high-frequency power RF during the overlap period OP(1)~OP(T-1) (intra-pulse feedback)]

[0064] First, the setting of the source frequency of the source high-frequency power RF in the first overlap period OP, i.e., overlap period OP(1), will be explained. The control unit 30c is configured to set the source frequency of the source high-frequency power RF in each of the multiple phase periods SP of each of the multiple waveform periods CY within the overlap period OP(1). Figure 5 and Figure 6 In the example shown, each of the multiple waveform periods CY within the overlapping period OP(1) comprises N phase periods SP(1) to SP(N). N is an integer greater than or equal to 2. The N phase periods SP(1) to SP(N) divide each of the multiple waveform periods CY into N phase periods. In each of the multiple waveform periods CY, the multiple phase periods SP can have the same time length or different time lengths. Furthermore, in the following explanation, phase period SP(n) represents the nth phase period among the phase periods SP(1) to SP(N). That is, phase period SP(n) represents any phase period among the multiple waveform periods CY within each of the multiple overlapping periods OP. In addition, phase period SP(m, n) represents the nth phase period among the waveform period CY(m). Furthermore, phase period SP(k, m, n) represents the nth phase period among the waveform period CY(m) within the kth overlapping period OP(k).

[0065] During the overlap period OP(1), the control unit 30c sets the source frequency of the source high-frequency power RF in the phase period SP(m,n) through intra-pulse feedback. Hereinafter, for generalization, the intra-pulse feedback applicable to the overlap period OP(k) will be explained. In the case of the overlap period OP(1), k is 1 in the intra-pulse feedback described below.

[0066] In intra-pulse feedback, the control unit 30c adjusts the source frequency of the source high-frequency power RF during the phase period SP(k,m,n) based on the change in the reflection level of the source high-frequency power RF. In one example, the reflection level of the source high-frequency power RF is represented by the power level Pr of the reflected wave of the source high-frequency power RF output from the sensor 31s. In intra-pulse feedback, the change in the reflection level is determined by using mutually different source frequencies of the source high-frequency power RF in the corresponding phase periods SP(n) of two or more waveform periods CY preceding the waveform period CY(k,m) within the overlap period OP(k).

[0067] In intra-pulse feedback, by using different source frequencies during the phase periods SP(n) of two or more waveform cycles CY, the relationship between the change in source frequency (frequency shift) and the change in the degree of reflection of the source high-frequency power can be determined. Therefore, according to intra-pulse feedback, the source frequency used in the phase periods SP(k,m,n) can be adjusted to reduce the degree of reflection based on the change in the degree of reflection. Furthermore, according to intra-pulse feedback, during the overlap period OP(k), the degree of reflection can be rapidly reduced in each of the multiple waveform cycles CY in which bias energy BE is applied to the bias electrode of the substrate support 11.

[0068] In one embodiment, the two or more waveform periods CY preceding the waveform period CY(k,m) include waveform period CY(k,m-M1) and waveform period CY(k,m-M2). Here, M1 and M2 are any natural numbers satisfying M1>M2. That is, waveform period CY(k,m-M2) is the waveform period following waveform period CY(k,m-M1).

[0069] In one embodiment, the waveform period CY(k, m-M1) can be the waveform period CY(k, m-2Q), and the waveform period CY(k, m-M2) can be the waveform period CY(k, mQ). Furthermore, Q is a natural number. Figure 5 In the example shown, "Q" and "M2" are "1", and "2Q" and "M1" are "2". "Q" can be an integer greater than 2.

[0070] In the intra-pulse feedback, the control unit 30c applies a frequency shift from one of the source frequencies f(k,m-M1,n) to the source frequency f(k,m-M2,n). Here, f(k,m,n) represents the source frequency of the source high-frequency power RF used by SP(k,m,n) during the phase period. f(k,m,n) is represented by f(k,m,n) = f(k,m-M2,n) + Δ(k,m,n). Δ(k,m,n) represents the amount of frequency shift. One of the frequency shifts is either a decrease in frequency or an increase in frequency. If one of the frequency shifts is a decrease in frequency, then Δ(k,m,n) has a negative value. If one of the frequency shifts is an increase in frequency, then Δ(k,m,n) has a positive value.

[0071] In addition, Figure 5 and Figure 6 In the waveform period CY(k, m-M1), the source frequencies in SP during multiple phase periods are the same, f0, but can be different. Furthermore, in Figure 5 and Figure 6 In the waveform period CY(k, m-M2), the source frequencies in each of the multiple phase periods SP are the same, set to decrease from the frequency f0, but can increase from the frequency f0.

[0072] In intra-pulse feedback, when the reflection level is reduced by using a source frequency f(k, m-M2, n) obtained through a frequency shift in one direction, the control unit 30c sets the source frequency f(k, m, n) to a frequency with a frequency shift in one direction relative to the source frequency f(k, m-M2, n). For example, when the power level Pr(k, m-M2, n) decreases from the power level Pr(k, m-M1, n) through a frequency shift in one direction, the control unit 30c sets the source frequency f(k, m, n) to a frequency with a frequency shift in one direction relative to the source frequency f(k, m-M2, n). Furthermore, Pr(k, m, n) represents the power level Pr of the reflected wave of the source high-frequency power RF during the phase period SP(k, m, n).

[0073] In one embodiment, the amount of frequency shift Δ(m,n) of one of the phase periods SP(k,m,n) can be the same as the amount of frequency shift Δ(m-M2,n) of the other of the phase periods SP(k,m-M2,n). That is, the absolute value of the amount of frequency shift Δ(k,m,n) can be the same as the absolute value of the amount of frequency shift Δ(k,m-M2,n). Alternatively, the absolute value of the amount of frequency shift Δ(k,m,n) can be greater than the absolute value of the amount of frequency shift Δ(k,m-M2,n). Alternatively, the absolute value of the amount of frequency shift Δ(k,m,n) can be set such that the greater the degree of reflection in the phase period SP(k,m-M2,n) (e.g., the power level Pr(k,m-M2,n) of the reflected wave), the larger it is. For example, the absolute value of the frequency shift Δ(k, m, n) can be determined as a function of the degree of reflection (e.g., the power level of the reflected wave Pr(k, m-M2, n)).

[0074] In intra-pulse feedback, the degree of reflection may increase by using a source frequency f(k, m-M2, n) obtained through a frequency shift of one of the sources. For example, the power level Pr(k, m-M2, n) of the reflected wave may increase from the power level Pr(k, m-M1, n) of the reflected wave due to a frequency shift of one source frequency. In this case, the control unit 30c can set the source frequency f(k, m, n) to a frequency with a frequency shift of the other source frequency f(k, m-M2, n). Furthermore, the source frequency of the phase period SP(n) of two or more waveform periods preceding the waveform period CY(k, m) can be updated to have a frequency shift of the source frequency of SP(n) relative to the phase period of the previous waveform period. In this case, if the degree of reflection (e.g., the power level Pr of the reflected wave) or their average value of SP(n) during the phase periods of the two or more waveform periods tends to increase, a frequency shift of the other source frequency can be applied to the source frequency of SP(n) during the phase period of the waveform period CY(k, m). For example, the source frequency of the phase period SP(n) of the waveform period CY(k,m) can be set to a frequency that has a frequency shift relative to the source frequency of the earliest waveform period among the two or more waveform periods.

[0075] Furthermore, in intra-pulse feedback, when using a source frequency f(k, m, n) obtained by frequency shifting one of the components, the degree of reflection may increase. For example, the power level Pr(k, m, n) of the reflected wave may increase from the power level Pr(k, m - M2, n) of the reflected wave due to the frequency shift of one component. In this case, the control unit 30c can set the source frequency in the phase period SP(n) within the waveform period CY(k, m + M3) as the intermediate frequency. The waveform period CY(k, m + M3) is the period following the waveform period CY(k, m). M3 is a natural number that can satisfy M3 = M2. The intermediate frequency that can be set in the phase period SP(k, m + M3, n) is the frequency between f(k, m - M2, n) and f(k, m, n), or it can be the average value of f(k, m - M2, n) and f(k, m, n).

[0076] Furthermore, in intra-pulse feedback, it is possible that the degree of reflection (e.g., power level Pr) may be greater than a predetermined threshold when an intermediate frequency is used in the phase period SP(k, m+M3, n). In this case, the control unit 30c can set the source frequency in the phase period SP(n) within the waveform period CY(k, m+M4) to a frequency with a frequency shift relative to the intermediate frequency. The waveform period CY(k, m+M4) is the period following the waveform period CY(k, m+M3). M4 is a natural number that satisfies M4 = M1. The threshold is predetermined. The absolute value of the frequency shift Δ(1, m+M4, n) is greater than the absolute value of the frequency shift Δ(1, m, n). In this case, it is possible to prevent the degree of reflection (e.g., the power level Pr of the reflected wave) from failing to decrease from a local minimum. In addition, the thresholds used for the multiple phase periods SP in each of the multiple waveform periods CY within the overlapping period OP(k) can be the same or different from each other.

[0077] The setting of the source frequency in the overlapping period OP(k) (where k is 2 or more and T-1 or less, and T is an integer of 3 or more) will be explained below. The source frequency of the multiple phase periods SP in the multiple waveform periods CY within the overlapping period OP(k) can be set by the pulse feedback described above. In addition, in setting the source frequency of the multiple phase periods SP in the waveform period CY(1) within the overlapping period OP(k), the waveform period CY(M-1) and the waveform period CY(M) within the overlapping period OP(k-1) can be used as the waveform period CY(k, m-M1) and the waveform period CY(k, m-M2). In addition, the waveform period CY(M) is the last waveform period in each overlapping period. In addition, in setting the source frequency of the source high-frequency power RF in the multiple phase periods SP in the waveform period CY(2) within the overlapping period OP(k), the waveform period CY(M) within the overlapping period OP(k-1) and the waveform period CY(1) within the overlapping period OP(k) can be used as the waveform period CY(k, m-M1) and the waveform period CY(k, m-M2).

[0078] In another embodiment, the source frequency of the multiple phase periods SP in the multiple waveform periods CY within the overlapping period OP(k) (k is 1 or more and T-1 or less, T is an integer of 3 or more) can be set using the individual frequencies registered in a pre-prepared table.

[0079] [Setting the source frequency of the source high-frequency power RF during the overlap period after OP(T) (inter-pulse feedback)]

[0080] The following is for reference Figure 8 The setting of the source frequency of the source high-frequency power RF in the Tth (T is an integer greater than or equal to 3) overlap period OP(k) is explained. Figure 8 This is a timing diagram of an example of bias energy and the source frequency of the source high-frequency power.

[0081] The control unit 30c is configured to set the source frequency of the source high-frequency power RF in each of the multiple waveform periods CY and multiple phase periods SP of the multiple overlapping periods OP after the second overlapping period by means of inter-pulse feedback.

[0082] In inter-pulse feedback, the control unit 30c adjusts the source frequency f(k, m, n) based on the change in the reflection level of the source high-frequency power RF. In one example, the reflection level of the source high-frequency power RF is represented by the power level Pr of the reflected wave of the source high-frequency power RF output from the sensor 31s. In inter-pulse feedback, the change in the reflection level is determined by using the source frequencies of the source high-frequency power RF with different values ​​for the corresponding phase periods SP(n) within the waveform period CY(m) within two or more overlap periods OP preceding the overlap period OP(k).

[0083] In inter-pulse feedback, by using different source frequencies during the same phase period within the same waveform cycle in each of two or more overlapping periods of OP, the relationship between the change in source frequency (frequency shift) and the change in the degree of reflection of the source high-frequency power can be determined. Therefore, according to inter-pulse feedback, the source frequency used in the phase period SP(k,m,n) can be adjusted to reduce the degree of reflection based on the change in the degree of reflection. Furthermore, according to intra-pulse feedback, the degree of reflection can be rapidly reduced in each of the multiple waveform cycles CY in each of the multiple overlapping periods of OP.

[0084] In one embodiment, the two or more overlapping periods OP preceding the overlapping period OP(k) include the (k-K1)th overlapping period OP(k-K1) and the (k-K2)th overlapping period OP(k-K2). Here, K1 and K2 are natural numbers that satisfy K1>K2.

[0085] In one embodiment, the overlap period OP(k-K1) is the overlap period OP(k-2). The overlap period OP(k-K2) is the overlap period following the overlap period OP(k-K1), and in one embodiment, it is the overlap period OP(k-1). That is, in one embodiment, K2 and K1 are 1 and 2, respectively.

[0086] The control unit 30c applies a frequency shift of one of the source frequencies from the phase period SP(k-K1, m, n) to the source frequency f(k-K2, m, n) in the phase period SP(k-K2, m, n). Here, f(k, m, n) represents the source frequency of the source high-frequency power RF used in the phase period SP(k, m, n). f(k, m, n) is represented by f(k, m, n) = f(k-K2, m, n) + Δ(k, m, n). Δ(k, m, n) represents the amount of frequency shift. One of the frequency shifts is either a decrease in frequency or an increase in frequency. If one of the frequency shifts is a decrease in frequency, then Δ(k, m, n) has a negative value. If one of the frequency shifts is an increase in frequency, then Δ(k, m, n) has a positive value.

[0087] In addition, Figure 8 In the waveform period CY(2,1), the source frequencies in each of the multiple phase periods SP are the same, set to decrease from the frequency f0, but can also increase from the frequency f0.

[0088] In inter-pulse feedback, when the reflection level decreases when using a source frequency f(k-K2, m, n) obtained by a frequency shift of one side, the control unit 30c sets the source frequency f(k, m, n) to a frequency with a frequency shift of one side relative to the source frequency f(k-K2, m, n). For example, when the power level Pr(k-K2, m, n) decreases from the power level Pr(k-K1, m, n) due to a frequency shift of one side, the control unit 30c sets the source frequency f(k, m, n) to a frequency with a frequency shift of one side relative to the source frequency f(k-K2, m, n). Furthermore, Pr(k, m, n) represents the power level Pr of the reflected wave of the source high-frequency power RF in the phase period SP(k, m, n). Additionally, the source frequency of the phase period SP(m, n) of each of two or more overlapping periods preceding the overlapping period OP(k) can be updated to have a frequency shift of one side relative to the source frequency of the phase period SP(m, n) of the previous overlapping period. In this case, if the reflection levels (e.g., the power level Pr of the reflected wave) or their average values ​​during the phase periods SP(m,n) of the two or more overlapping periods tend to increase, a frequency shift of the other can be applied to the source frequency of the phase period SP(m,n) of the overlapping period OP(k). For example, the source frequency of the phase period SP(m,n) of the overlapping period OP(k) can be set to a frequency with a frequency shift of the other relative to the source frequency of the earliest overlapping period among the two or more overlapping periods.

[0089] In one embodiment, the amount of frequency shift Δ(m,n) of one of the phase periods SP(k,m,n) can be the same as the amount of frequency shift Δ(k-K2,m,n) of the other of the phase periods SP(k-K2,m,n). That is, the absolute value of the amount of frequency shift Δ(k,m,n) can be the same as the absolute value of the amount of frequency shift Δ(k-K2,m,n). Alternatively, the absolute value of the amount of frequency shift Δ(k,m,n) can be greater than the absolute value of the amount of frequency shift Δ(k-K2,m,n). Alternatively, the absolute value of the amount of frequency shift Δ(k,m,n) can be set such that the greater the degree of reflection in the phase period SP(k-K2,m,n) (e.g., the power level Pr(k-K2,m,n) of the reflected wave), the greater it is. For example, the absolute value of the amount of frequency shift Δ(k,m,n) can be determined as a function of the degree of reflection (the power level Pr(k-1,m,n) of the reflected wave).

[0090] In inter-pulse feedback, the degree of reflection may increase by using a source frequency f(k-K2, m, n) obtained through a frequency shift of one of the sources. For example, the power level Pr(k-1, m, n) of the reflected wave may increase from the power level Pr(k-2, m, n) of the reflected wave due to a frequency shift of one source. In this case, the control unit 30c can set the source frequency f(k, m, n) to a frequency that has a frequency shift of the other source frequency f(k-K2, m, n).

[0091] Furthermore, in inter-pulse feedback, when using a source frequency f(k, m, n) obtained by frequency shifting one of the pulses, the degree of reflection may increase. For example, the power level Pr(k, m, n) of the reflected wave may increase from the power level Pr(k-K2, m, n) of the reflected wave due to the frequency shift of one pulse. In this case, the control unit 30c can set the source frequency in the phase period SP(k+K3, m, n) to an intermediate frequency. That is, in this case, the source frequency in the phase period SP(n) within the waveform period CY(m) within the overlap period OP(k+K3) can be set to an intermediate frequency. The overlap period OP(k+K3) is the period after the overlap period OP(k). K3 is a natural number that can satisfy K3=K2. The intermediate frequency that can be set in the phase period SP(k+K3,m,n) is the frequency between f(k-K2,m,n) and f(k,m,n), or it can be the average value of f(k-K2,m,n) and f(k,m,n).

[0092] Furthermore, in inter-pulse feedback, it is possible that the degree of reflection (e.g., power level Pr) may exceed a predetermined threshold when the aforementioned intermediate frequency is used during the phase period SP(k+K3, m, n). In this case, the control unit 30c can set the source frequency in the phase period SP(k+K4, m, n) to a frequency with a frequency shift relative to the intermediate frequency. That is, in this case, the other frequency shift can be applied to the source frequency in the phase period SP(n) within the waveform period CY(m) within the overlap period OP(k+K4). The overlap period OP(k+K4) is the period following the overlap period OP(k+K3). K4 is a natural number that satisfies K4>K3, or K4=K1. The threshold is predetermined. The absolute value of the other frequency shift Δ(k+K4, m, n) is greater than the absolute value of the first frequency shift Δ(k, m, n). In this case, it is possible to prevent the degree of reflection (e.g., the power level Pr of the reflected wave) from failing to decrease from a local minimum. In addition, the thresholds used for the multiple phase periods SP within the multiple waveform periods CY of the multiple overlapping periods OP can be the same or different.

[0093] The plasma processing apparatus 1 can use a representative value of the measured values ​​during each phase period as the degree of reflection during each phase period. The representative value can be the average or maximum value of the measured values ​​during each phase period. In addition, the plasma processing apparatus 1 can use at least one of the following as measured values: the power level Pr of the reflected wave, the ratio of the power level Pr of the reflected wave to the output power level of the source high-frequency electrical power RF (hereinafter referred to as "reflectivity"), the phase difference θ between voltage V and current I, and the impedance Z of the load side of the high-frequency power supply 31.

[0094] The plasma processing apparatus 1 may include, in addition to or replacing, the aforementioned sensor 31s, a VI sensor. The VI sensor measures the voltage V and current I in the power supply path of the source high-frequency power RF between the high-frequency power supply 31 and the high-frequency electrode. The VI sensor may be connected between the high-frequency power supply 31 and the matching transformer 31m. Alternatively, the VI sensor may be connected between the matching transformer 31m and the high-frequency electrode. For example, the VI sensor may be connected between the junction of the electrical path extending from the matching transformer 31m towards the bias electrode and the electrical path extending from the matching transformer 32m towards the bias electrode, and the bias electrode. Alternatively, the VI sensor may be connected between this junction point and the matching transformer 31m. The VI sensor may also be part of the matching transformer 31m.

[0095] The source frequencies used for respective phases SP during each waveform period CY can be varied according to the voltage V, the current I, and the phase difference θ between the voltage V and the current I, such that the impedance on the load side of the high-frequency power supply 31 approaches the matching point. Further, the variable impedance of the matcher 31m can be adjusted according to the voltage V, the current I, and the phase difference θ, such that the impedance Z on the load side of the high-frequency power supply 31 approaches the matching point. Additionally, when the characteristic impedance of the power supply path of the source high-frequency power RF is 50 Ω, the real resistance component of the matching point is 50 Ω, and the phase difference θ is 0°.

[0096] Hereinafter, referring to Figure 9 , a method for controlling the source frequency of the source high-frequency power in an exemplary embodiment will be described. Figure 9 is a flowchart of a method for controlling the source frequency of the source high-frequency power in an exemplary embodiment. Figure 9 The method MT shown starts at step STa or step STb. At step STa, a pulse BEP of the bias energy BE is applied to the bias electrode of the substrate support portion 11 of the plasma processing apparatus 1. The pulse BEP of the bias energy BE is applied to the bias electrode during each of the plurality of pulse periods PP.

[0097] At step STb, in order to generate plasma in the chamber, source high-frequency power RF is supplied from a high-frequency power supply (e.g., high-frequency power supply 31). As Figure 3 shown in (a) of Figure 3 shown in (b) of Figure 4 shown in (a) of Figure 4 shown in (b) of

[0098] At step STc, the source frequencies of the source high-frequency power RF used during each of the plurality of phase periods SP included in each of the plurality of waveform periods CY included in each of the plurality of overlap periods OP are set. In the inter-pulse feedback, the source frequency in the phase period SP(k, m, n) within the waveform period CY(m) in the overlap period OP(k) is adjusted according to the change in the reflection degree of the source high-frequency power. In the inter-pulse feedback, the change in the reflection degree (e.g., the power level Pr of the reflected wave) is determined by using mutually different source frequencies in the corresponding phase periods SP(n) within the waveform period CY(m) in two or more overlap periods before the overlap period OP(k). Regarding the inter-pulse feedback, refer to the above description.

[0099] Hereinafter, referring to Figure 10 shown in (a) to Figure 10 shown in (d) of Figure 10 shown in (a) to Figure 10 shown in (d) of aThe overlapping periods are OP(1)~OP(K) a Here, K a It is a natural number greater than 2.

[0100] High-frequency power supply 31 can operate during overlap from OP(1) to OP(K). a Each contains the first to the Mth waveform periods CY. a Each waveform period CY(1)~CY(M) a Initial processing is performed on each of the components. Here, M... a It is a natural number. In the initial processing, a waveform period CY(1) to CY(M) can be used. a Each frequency set can be a frequency set group containing multiple frequency sets, and these frequency sets can be different from each other. Furthermore, overlap periods OP(1) to OP(K) can be used. a Each frequency set can be a different set than the others. Furthermore, the multiple frequency sets and frequency groups can be stored in the storage unit of control unit 2 or control unit 30c.

[0101] High-frequency power supply 31 can operate during overlap from OP(1) to OP(K). a In each of the multiple waveform periods CY, the waveform period CY(M) is... a Then, the above-mentioned intra-pulse feedback is performed. That is, the high-frequency power supply 31 can perform OP(1)~OP(K) during the overlap period. a The waveform period CY(M) contained in each a The above-mentioned intra-pulse feedback is performed in +1)~CY(M).

[0102] In one embodiment, the multiple overlapping periods OP may further include from the (K)th a +1) to the Kth b OP(K) during the overlapping period a +1)~OP(K b Here, K b Yes (K) a Natural numbers greater than or equal to +1 can also satisfy K. b =K a +1.

[0103] High-frequency power supply 31 can OP(K) during overlap. a +1)~OP(K b Each contains the first to the Mth waveform periods CY. b1 Each waveform period CY(1)~CY(M) b1 The initial processing described above is performed on each of M. Here, M b1 It is a natural number. M b1 and Ma It can satisfy M b1 <M a .

[0104] High-frequency power supply 31 can OP(K) during overlap. a +1)~OP(K b The Mth wave of each of the multiple waveform periods CY contained in each b1 +1) of the Mth b2 Each waveform period CY(M) b1 +1)~CY(M b2 The above-mentioned inter-pulse feedback is performed in ). Here, M b2 Is it satisfying M? b2 >M b1 The natural number.

[0105] High-frequency power supply 31 can OP(K) during overlap. a +1)~OP(K b In each of the waveform periods CY(M) b2 Then, the aforementioned intra-pulse feedback is performed. That is, the high-frequency power supply 31 can perform OP(K) feedback during the overlap period. a +1)~OP(K b The waveform period CY(M) contained in each b2 The above-mentioned intra-pulse feedback is performed in +1)~CY(M).

[0106] In addition, the high-frequency power supply 31 can be used in the (K)th... b +1) during the final overlap period OP(K) b +1)~OP(K) each contain the first~Mth c Each waveform period CY(1)~CY(M) c The above-mentioned inter-pulse feedback is performed in ). Here, M c It is a natural number. Furthermore, the high-frequency power supply 31 can OP(K) during the overlap period. b In each of +1)~OP(K), within the waveform period CY(M) c Then, the aforementioned intra-pulse feedback is performed. That is, the high-frequency power supply 31 can perform OP(K) feedback during the overlap period. b The waveform periods CY(M) contained in each of +1)~OP(K) c The above-mentioned intra-pulse feedback is performed in +1)~CY(M).

[0107] In one embodiment, the high-frequency power supply 31 can, during at least one overlap period from the second to the last overlap period OP(2) to OP(K), convert the waveform period CY(M) to M. FThe source frequency in the phase period SP(n) within the at least one overlapping period is set to the source frequency of the same phase period SP(n) within the last waveform period CY(M) contained in the preceding overlapping period. Waveform period CY(M) F The waveform period CY(M) is the initial waveform period for applying intra-pulse feedback among a plurality of waveform periods CY within the at least one overlapping period. Alternatively, the high-frequency power supply 31 may, during the at least one overlapping period, apply waveform period CY(M) to the waveform period CY(M). F The source frequency in the phase period SP(n) within the at least one overlapping period is set to the average of the source frequencies of the same phase period SP(n) of two or more waveform periods containing the last waveform period CY(M) of the preceding overlapping period. These two or more waveform periods can be the waveform periods CY(MM) contained in the preceding overlapping period. L +1)~CY(M). Here, M L It is the number of cycles of the two or more waveforms.

[0108] In one embodiment, the above-mentioned M a M b1 M b2 and M c These can be preset values. That is, the number of waveform periods to be processed initially, M. a and M b1 And the number of waveform periods, M, used for inter-pulse feedback. b2 and M c It can be preset.

[0109] Alternatively, the high-frequency power supply 31 can be configured to terminate the initial processing when the monitoring value reflecting the degree of reflection enters a specified range during the initial processing. Furthermore, the high-frequency power supply 31 can be configured to terminate the initial processing when the monitoring value reflecting the degree of reflection enters a specified range during inter-pulse feedback.

[0110] As a monitoring value, more than one measured value can be used. Alternatively, as a monitoring value, the change (rate of change or difference) of the average value of more than one measured value during the same phase period of the waveform cycle can be used. Alternatively, as a monitoring value, the change (rate of change or difference) of the average value of several waveform cycles of more than one measured value during the same phase period of the waveform cycle can be used. Alternatively, as a monitoring value, the change (rate of change or difference) of the average value of more than one measured value during the same phase period of the waveform cycle can be used. Alternatively, as a monitoring value, the deviation of more than one measured value during one or more waveform cycles or the deviation of several waveform cycles of more than one measured value during the same phase period of the waveform cycle can be used. More than one measured value may include one or more of the power level Pr of the reflected wave, the aforementioned reflectivity, the phase difference θ between voltage V and current I, impedance Z, Vpp (peak-to-peak voltage) of the bias electrode, the self-bias voltage Vdc of the bias electrode, and the luminescence state of the plasma.

[0111] The above descriptions illustrate various illustrative embodiments, but are not limited to those described above. Various additions, omissions, substitutions, and modifications can be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

[0112] As described above, in another embodiment, the plasma processing apparatus can be an inductively coupled plasma processing apparatus, an ECR plasma processing apparatus, a helical wave excited plasma processing apparatus, or a surface wave plasma processing apparatus. In any plasma processing apparatus, a source high-frequency power RF is used for plasma generation, and the source frequency used in the SP during multiple phases of multiple waveform periods CY is adjusted as described above with respect to plasma processing apparatus 1.

[0113] Furthermore, in intra-pulse feedback, the source frequency of the source high-frequency power RF in the phase period SP(k,m,n) can be determined as the frequency that minimizes the reflection degree, based on two or more reflection degrees (e.g., power levels Pr) obtained by using the source frequencies of the source high-frequency power RF in the corresponding phase periods SP(n) of two or more waveform periods CY(k,m) before the overlapping period OP(k). The frequency that minimizes the reflection degree can also be determined by using the least squares method of each of these different frequencies and their corresponding reflection degrees.

[0114] Furthermore, in inter-pulse feedback, the source frequency f(k, m, n) can be determined as the frequency that minimizes the reflection degree, based on two or more reflection degrees (e.g., power levels Pr) obtained by using the source frequencies of mutually different source high-frequency power RFs within the corresponding phase periods SP(n) of the waveform period CY(m) within two or more overlapping periods OP preceding the overlapping period OP(k). The frequency that minimizes the reflection degree can also be determined by using the least squares method of each of these mutually different frequencies and their corresponding reflection degrees.

[0115] In addition, this disclosure includes the following further embodiments E1-E9.

[0116] [E1]

[0117] A plasma processing device, characterized in that it comprises:

[0118] chamber;

[0119] A substrate support portion, having a bias electrode, is disposed within the cavity;

[0120] The high-frequency power supply is configured to generate high-frequency electricity in order to generate plasma within the aforementioned chamber;

[0121] The bias power supply is configured to apply a pulse of bias energy to the bias electrode during each of a plurality of pulses.

[0122] The sensor is configured to output the reflected wave of the aforementioned high-frequency power returned from the load of the aforementioned high-frequency power source; and

[0123] The control unit is configured to control the aforementioned high-frequency power supply.

[0124] The aforementioned bias power supply is configured such that, during each of the multiple cycles within the aforementioned plurality of pulses, the aforementioned bias energy is applied to the aforementioned bias electrode.

[0125] The aforementioned control unit is configured to set the frequency of the aforementioned high-frequency power during the period in which the aforementioned high-frequency power is supplied during the aforementioned plurality of pulses, i.e., during the multiple phase periods of each of the multiple overlapping periods.

[0126] The aforementioned control unit is configured to adjust the frequency of the aforementioned high-frequency power in the nth phase period of the mth period within the aforementioned multiple overlapping periods based on the change in the power level of the aforementioned reflected wave output from the aforementioned sensor when different frequencies of the aforementioned high-frequency power are used in the corresponding phase periods within the mth cycle of each of the two or more overlapping periods preceding the kth overlapping period.

[0127] [E2]

[0128] The plasma processing apparatus according to embodiment E1 is characterized in that:

[0129] The aforementioned two or more overlapping periods include a first overlapping period and a second overlapping period following the first overlapping period.

[0130] The aforementioned control unit is configured such that, when the power level of the reflected wave is reduced by applying a frequency shift, which is either a decrease or an increase in the frequency of the high-frequency power in the nth phase period of the mth period within the first overlap period, to the frequency of the high-frequency power in the nth phase period of the mth period within the second overlap period, the aforementioned frequency of the high-frequency power in the nth phase period of the mth period within the kth overlap period is set to a frequency with a frequency shift relative to the frequency of the high-frequency power in the nth phase period of the mth period within the second overlap period.

[0131] [E3]

[0132] The plasma processing apparatus according to embodiment E2 is characterized in that:

[0133] The aforementioned control unit is configured such that, when the power level of the reflected wave is increased by setting the frequency of the high-frequency power in the nth phase period of the mth cycle within the kth overlapping period to a frequency that has a frequency shift relative to the frequency of the high-frequency power in the nth phase period of the mth cycle within the second overlapping period, the frequency of the high-frequency power in the nth phase period of the mth cycle within the third overlapping period after the kth overlapping period is set to an intermediate frequency between the frequency of the high-frequency power in the nth phase period of the mth cycle within the second overlapping period and the frequency of the high-frequency power in the nth phase period of the mth cycle within the kth overlapping period.

[0134] [E4]

[0135] The plasma processing apparatus according to embodiment E3 is characterized in that:

[0136] The aforementioned control unit is configured such that, when the power level of the reflected wave is greater than a threshold during the nth phase period of the mth cycle within the third overlap period, if the aforementioned intermediate frequency is used, the frequency of the aforementioned high-frequency power during the nth phase period of the mth cycle within the fourth overlap period after the third overlap period is set to a frequency with a frequency shift relative to the aforementioned intermediate frequency, wherein the frequency shift has an absolute value greater than the absolute value of the frequency shift.

[0137] [E5]

[0138] The plasma processing apparatus according to embodiment E2 is characterized in that:

[0139] The absolute value of the frequency shift of the aforementioned frequency of the aforementioned high-frequency power during the aforementioned nth phase period within the aforementioned mth period of the aforementioned kth overlap period is greater than the absolute value of the frequency shift of the aforementioned frequency of the aforementioned high-frequency power during the aforementioned nth phase period within the aforementioned mth period of the aforementioned second overlap period.

[0140] [E6]

[0141] The plasma processing apparatus according to embodiment E1 is characterized in that:

[0142] The aforementioned two or more overlapping periods include a first overlapping period and a second overlapping period following the first overlapping period.

[0143] The aforementioned control unit is configured such that, when the power level of the reflected wave is increased by applying a frequency shift, either a decrease or an increase in the frequency of the high-frequency power in the nth phase period of the mth period within the first overlap period, to the frequency of the high-frequency power in the nth phase period of the mth period within the second overlap period, the aforementioned frequency of the high-frequency power in the nth phase period of the mth period within the kth overlap period is set to a frequency with a frequency shift relative to the frequency of the high-frequency power in the nth phase period of the mth period within the second overlap period.

[0144] [E7]

[0145] The plasma processing apparatus according to any one of embodiments E1-E6 is characterized in that:

[0146] The aforementioned bias energy is high-frequency power having a bias frequency that defines the aforementioned plurality of cycles, including pulses of voltage applied to the aforementioned bias electrode in each of the aforementioned plurality of cycles defined by the bias frequency.

[0147] [E8]

[0148] A method for controlling the frequency of high-frequency power, characterized by comprising the following steps:

[0149] In each of the multiple pulse periods, a pulse of bias energy is applied to a bias electrode disposed in a substrate support within the cavity of the plasma processing apparatus. The pulse of bias energy includes bias energy applied to the bias electrode in each of the multiple cycles in each of the multiple pulse periods.

[0150] High-frequency power is supplied from a high-frequency power source to generate plasma within the aforementioned chamber; and

[0151] The frequency of the high-frequency power supplied during the aforementioned multiple pulse periods is set to the frequency of the multiple phase periods within each of the multiple periods contained in the multiple overlapping periods.

[0152] The frequency of the aforementioned high-frequency power in the nth phase period of the mth cycle within the kth overlapping period of the aforementioned plurality of overlapping periods is adjusted according to the change in the power level of the reflected wave of the aforementioned high-frequency power when the corresponding phase periods of the mth cycle in each of the two or more overlapping periods preceding the kth overlapping period of the aforementioned plurality of overlapping periods use mutually different frequencies of the aforementioned high-frequency power.

[0153] As can be understood from the above description, various embodiments of this disclosure have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are indicated by the appended claims.

[0154] Symbol Explanation

[0155] 1…Plasma processing device, 10…Plasma processing chamber, 11…Substrate support, 31…High-frequency power supply, 32…Bias power supply, 31s…Sensor, 30c…Control unit.

Claims

1. A plasma processing device, characterized in that, include: chamber; A substrate support portion, having a bias electrode, is disposed within the cavity; The high-frequency power supply is configured to generate high-frequency power for generating plasma within the cavity; and The bias power supply is configured to apply a pulse of bias energy to the bias electrode during each of a plurality of pulses. The bias power supply is configured such that, in each of the plurality of pulse periods, bias energy having a waveform period is periodically applied to the bias electrode. The high-frequency power supply is configured as follows: The source frequency of the source high-frequency power is set in each of the multiple phase periods of the multiple waveform periods of the bias energy contained in the multiple overlap periods that overlap with the multiple pulse periods. The high-frequency power supply is configured to perform inter-pulse feedback: The source frequency of the bias energy in the nth phase period of the mth waveform period is adjusted based on the change in the degree of reflection of the source high-frequency power in the case where different source frequencies are used in the nth phase period of the mth waveform period of each of the two or more overlapping periods preceding the kth overlapping period.

2. The plasma processing apparatus according to claim 1, characterized in that: The two or more overlapping periods include the (k-K1)th overlapping period and the (k-K2)th overlapping period, where K1 and K2 are natural numbers satisfying K1>K2. The inter-pulse feedback includes: When the reflection degree is reduced by applying a frequency shift, either a decrease or an increase in the source frequency during the nth phase period of the m-th waveform period within the (k-K1)-th overlap period, to the source frequency during the nth phase period of the m-th waveform period within the (k-K2)-th overlap period, the source frequency during the nth phase period of the m-th waveform period within the k-th overlap period is set to a frequency having a frequency shift of said one relative to the source frequency during the nth phase period of the m-th waveform period within the (k-K2)-th overlap period.

3. The plasma processing apparatus according to claim 2, characterized in that: The inter-pulse feedback also includes: When the reflection degree is increased by setting the source frequency in the nth phase period of the mth waveform period within the kth overlap period to a frequency having a frequency shift relative to the source frequency in the nth phase period of the mth waveform period within the (k-K2)th overlap period, the source frequency in the nth phase period of the mth waveform period within the (k+K3)th overlap period after the kth overlap period is set to an intermediate frequency between the source frequency in the nth phase period of the mth waveform period within the (k-K2)th overlap period and the source frequency in the nth phase period of the mth waveform period within the kth overlap period.

4. The plasma processing apparatus according to claim 3, characterized in that: The inter-pulse feedback also includes: If the degree of reflection is greater than a threshold when the intermediate frequency is used during the nth phase period of the mth waveform period within the (k+K3)th overlap period, the source frequency during the nth phase period of the mth waveform period within the overlap period after the (k+K3)th overlap period is set to a frequency with a frequency shift relative to the intermediate frequency, wherein the frequency shift has an absolute value greater than the absolute value of the frequency shift.

5. The plasma processing apparatus according to claim 2, characterized in that: The absolute value of the frequency shift of one of the source frequencies in the nth phase period within the mth waveform period during the kth overlap period is greater than the absolute value of the frequency shift of one of the source frequencies in the nth phase period within the mth waveform period during the (k-K2)th overlap period.

6. The plasma processing apparatus according to claim 1, characterized in that: The two or more overlapping periods include the (k-K1)th overlapping period and the (k-K2)th second overlapping period, where K1 and K2 are natural numbers and K1 > K2. The inter-pulse feedback includes: When the degree of reflection is increased by applying a frequency shift, either a decrease or an increase of the source frequency in the nth phase period of the m-th waveform period within the (k-K1)-th overlap period, to the source frequency in the nth phase period of the m-th waveform period within the (k-K2)-th overlap period, the source frequency in the nth phase period of the m-th waveform period within the k-th overlap period is set to a frequency with a frequency shift relative to the source frequency in the nth phase period of the m-th waveform period within the (k-K2)-th overlap period.

7. The plasma processing apparatus according to any one of claims 1 to 6, characterized in that: The bias energy is a bias high-frequency power having a bias frequency that is the reciprocal of the time length of the waveform period, including pulses of voltage applied to the bias electrode in each of the plurality of waveform periods having a time length that is the reciprocal of the bias frequency.

8. The plasma processing apparatus according to any one of claims 1 to 7, characterized in that: The multiple overlapping periods include the first to the Kth period. a During the overlapping period, here, K a For natural numbers greater than 2, The high-frequency power supply is further configured as follows: In the first to the Kth a The first to the Mth of the plurality of waveform periods contained in each overlapping period a In each of the waveform cycles, an initial process is performed to set the source frequency during the plurality of phase periods to a plurality of frequencies contained in a pre-prepared frequency set. In the first to the Kth a In each of the overlapping periods, in the Mth wave of the plurality of waveform periods a After a waveform cycle, an intra-pulse feedback is performed to adjust the source frequency in the nth phase of the m-th waveform cycle based on the change in the degree of reflection of the source high-frequency power during the nth phase of each of the two or more waveform cycles preceding the m-th waveform cycle when different source frequencies are used.

9. The plasma processing apparatus according to claim 8, characterized in that: The multiple overlapping periods also include the (K)th a +1) of the Kth generation b During the overlapping period, here, K b Yes (K) a Natural numbers greater than or equal to 1, The high-frequency power supply is configured as follows: In the (K)th a +1) of the Kth terms b The first to the Mth of the plurality of waveform periods contained in each overlapping period b1 The initial processing is performed in each of the waveform cycles. In the (K)th a +1) of the Kth terms b The (M)th of the plurality of waveform periods contained in each of the overlapping periods b1 +1) of the Mth b2 The inter-pulse feedback is performed during each waveform cycle. In the (K)th a +1) of the Kth terms b In each of the overlapping periods, in the Mth period b2 The intra-pulse feedback is performed after one waveform cycle. Here, the M b1 and the M a Satisfy M b1 <M a .

10. The plasma processing apparatus according to claim 9, characterized in that: The high-frequency power supply is configured as follows: The (K)th during the plurality of overlapping periods b +1) the first to Mth of the plurality of waveform periods contained in each of the last overlapping periods. c The inter-pulse feedback is performed within each waveform cycle. In the (K)th b +1) of the last overlapping periods, in the Mth period c The intra-pulse feedback is performed after one waveform cycle.

11. The plasma processing apparatus according to any one of claims 8 to 10, characterized in that: The high-frequency power supply is configured as follows: In at least one of the second to last overlapping periods among the plurality of overlapping periods, the source frequency in the nth phase period within the waveform period in which the intra-pulse feedback is initially applied among the plurality of waveform periods is set to the source frequency of the nth phase period within the last waveform period of the plurality of waveform periods included in the preceding overlapping period of the at least one overlapping period among the plurality of overlapping periods, or the average of the source frequencies of the nth phase periods of two or more waveform periods including the last waveform period.

12. The plasma processing apparatus according to any one of claims 8 to 11, characterized in that: The high-frequency power supply is configured as follows: The initial processing ends when the monitoring value reflecting the degree of reflection enters a specified range during the initial processing.

13. A method for controlling the source frequency of high-frequency power, characterized in that, Includes the following steps: In each of the plurality of pulses, a pulse of bias energy is applied to a bias electrode disposed in a substrate support within a cavity of a plasma processing apparatus. The bias energy has a waveform period and is periodically applied to the bias electrode in each of the plurality of pulses. In order to generate plasma in the chamber, high-frequency power is supplied from the source power supply; as well as The source frequency of the source high-frequency power is set in each of the multiple phase periods of the multiple waveform periods of the bias energy contained in the multiple overlap periods that overlap with the multiple pulse periods. The source frequency of the bias energy in the nth phase period of the mth waveform period within the kth overlap period of the plurality of overlap periods is adjusted according to the change in the degree of reflection of the source high-frequency power when the nth phase period of the mth waveform period in each of the two or more overlap periods preceding the kth overlap period uses mutually different source frequencies.

Images