Plasma processing equipment

Abstract

To provide a technique of reducing the level of reflection of a source high-frequency power in a plasma processing apparatus.SOLUTION: A plasma processing apparatus comprises a chamber, a substrate support part, a high-frequency power supply, and a bias power supply. The high-frequency power supply generates a source high-frequency power for generating a plasma in the chamber. The bias power supply applies a pulse of a bias energy to a bias electrode in each of a plurality of pulse periods. The high-frequency power supply sets a source frequency of the source high-frequency power in each of a plurality of phase periods of a plurality of overlapping periods that is overlapped to each of the plurality of pulse periods according to a change in the level of reflection of the source high-frequency power. The level of reflection is specified by using source frequencies different from each other in the same phase period in two or more previous overlapping periods.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to a plasma processing apparatus and a method for controlling the source frequency of source radio frequency power. [Background technology]

[0002] A plasma processing apparatus is used in plasma processing of a substrate. The plasma processing apparatus uses bias high frequency power to attract ions from plasma generated in a 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 source RF power reflection in plasma processing equipment. [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 has a bias electrode and is disposed within the chamber. The radio frequency power source is configured to generate a source radio frequency power to generate plasma within the chamber. The bias power source is configured to provide a pulse of bias energy to the bias electrode during each of a plurality of pulse periods. The bias power source is configured to periodically provide bias energy having a waveform period to the bias electrode during each of the plurality of pulse periods. The radio frequency power source is configured to set a source frequency of the source radio frequency power during each of a plurality of phase periods within each of a plurality of waveform periods of the bias energy included in each of a plurality of overlap periods. The plurality of overlap periods overlap with the plurality of pulse periods. The radio frequency power source is configured to perform pulse-to-pulse feedback. The pulse-to-pulse feedback includes adjusting a source frequency f(k,m,n) in response to a change in the degree of reflection of the source radio frequency power. f(k,m,n) is the source frequency during an nth phase period within an mth waveform period within a kth overlap period among the plurality of overlap periods. The change in the degree of reflection is determined by using different source frequencies in the nth phase period within the mth waveform period in each of two or more overlap periods before the kth overlap period. [Effects of the Invention]

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

[0007] [Figure 1] 1 is a diagram illustrating a schematic diagram of a plasma processing apparatus according to an exemplary embodiment; [Figure 2] 1 is a diagram illustrating a schematic diagram of a plasma processing apparatus according to an exemplary embodiment; [Figure 3]Each of (a) of FIG. 3 and (b) of FIG. 3 is a timing chart showing an example of the source high frequency power and the bias energy. [Figure 4] Each of (a) of FIG. 4 and (b) of FIG. 4 is a timing chart showing an example of the source high frequency power and the bias energy. [Figure 5] 10 is a timing chart showing an example of bias energy and source frequency of source high frequency power. [Figure 6] 10 is a timing chart of another example of bias energy and source frequency of source high frequency power. [Figure 7] 10 is a timing chart of another example of bias energy. [Figure 8] 10 is a timing chart showing an example of bias energy and source frequency of source high frequency power. [Figure 9] 1 is a flow diagram of a method for controlling a source frequency of source radio frequency power according to an exemplary embodiment. [Figure 10] Each of (a) to (d) of FIG. 10 is a timing chart of yet another example of bias energy. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various exemplary embodiments are described below.

[0009] 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 has a bias electrode and is disposed within the chamber. The radio frequency power source is configured to generate a source radio frequency power to generate plasma within the chamber. The bias power source is configured to provide a pulse of bias energy to the bias electrode during each of a plurality of pulse periods. The bias power source is configured to periodically provide bias energy having a waveform period to the bias electrode during each of the plurality of pulse periods. The radio frequency power source is configured to set a source frequency of the source radio frequency power during each of a plurality of phase periods within each of a plurality of waveform periods of the bias energy included in each of a plurality of overlap periods. The plurality of overlap periods overlap with the plurality of pulse periods. The radio frequency power source is configured to perform pulse-to-pulse feedback. The pulse-to-pulse feedback includes adjusting a source frequency f(k,m,n) in response to a change in the degree of reflection of the source radio frequency power. f(k,m,n) is the source frequency during an nth phase period within an mth waveform period within a kth overlap period among the plurality of overlap periods. The change in the degree of reflection is determined by using different source frequencies in the nth phase period within the mth waveform period in each of two or more overlap periods before the kth overlap period.

[0010] By using different source frequencies in the same phase period within the same waveform cycle in each of two or more overlap periods, it is possible to identify the relationship between a change in source frequency (frequency shift) and a change in the degree of reflection of the source high-frequency power. Therefore, according to the above embodiment, it is possible to adjust the source frequency used in the nth phase period within the mth waveform cycle within the kth overlap period in response to a change in the degree of reflection so as to reduce the degree of reflection. Furthermore, according to the above embodiment, it is possible to quickly reduce the degree of reflection in each of multiple waveform cycles within each of multiple overlap periods.

[0011] In one exemplary embodiment, the two or more overlapping periods may include a (k-K1)th overlapping period and a (k-K2)th overlapping period, where K1 and K2 are natural numbers satisfying K1>K2.

[0012] In one exemplary embodiment, the inter-pulse feedback may include imparting a source frequency f(k-K2,m,n) with one of two frequency shifts from the source frequency f(k-K1,m,n). The one of two frequency shifts may be one of a frequency decrease or an frequency increase. If the one of two frequency shifts results in a decrease in reflection, the inter-pulse feedback may set f(k,m,n) to a frequency with one of two frequency shifts relative to f(k-K2,m,n). If the one of two frequency shifts results in an increase in reflection, the inter-pulse feedback may set the source frequency f(k+K3,m,n) to an intermediate frequency. The intermediate frequency is a frequency between f(k-K2,m,n) and the source frequency f(k,m,n), where K3 is a natural number.

[0013] In one exemplary embodiment, the degree of reflection may be greater than a threshold when the intermediate frequency is used during the nth phase period in the mth waveform cycle within the (k+K3)th overlap period. In this case, the inter-pulse feedback may set the source frequency f(k+K4,m,n) to a frequency having another frequency shift relative to the intermediate frequency, where the other frequency shift has an absolute value greater than the absolute value of the one frequency shift, where K4 is a natural number satisfying K4>K3.

[0014] In one exemplary embodiment, the absolute value of one of the frequency shift amounts used to obtain f(k,m,n) may be greater than the absolute value of one of the frequency shift amounts used to obtain f(k-K2,m,n).

[0015] In one exemplary embodiment, the inter-pulse feedback may include imparting f(k-K2,m,n) with one frequency shift from f(k-K1,m,n). The one frequency shift may be one of a decrease and an increase in frequency. If using f(k-K2,m,n) resulting from one frequency shift results in an increased degree of reflection, the inter-pulse feedback may set f(k,m,n) to a frequency having the other frequency shift relative to f(k-K2,m,n).

[0016] In one exemplary embodiment, the bias energy may be bias radio frequency power having a bias frequency that is the inverse of the time length of a waveform period, and may include pulses of voltage applied to the bias electrode in each of a plurality of waveform periods, each having a time length that is the inverse of the bias frequency.

[0017] In one exemplary embodiment, the multiple overlapping periods are numbered from 1 to K a Contains the Kth overlapping period, where a is a natural number equal to or greater than 2. The high frequency power supply operates during the overlap period OP(1) to OP(K a ) are included in each of the waveform periods CY(1) to CY(M a In each of the overlap periods OP(1) to OP(K), an initial process may be performed to set the source frequencies in the multiple phase periods to multiple frequencies included in a frequency set prepared in advance. Here, OP(k) is the k-th overlap period among the multiple overlap periods. CY(m) is the m-th waveform period in each overlap period. The high frequency power source is a ) for each waveform period CY(M a Intra-pulse feedback may be performed in waveform periods after CY(m). The intra-pulse feedback may include adjusting the source frequency f(k,m,n) in response to changes in the degree of reflection of source RF power when different source frequencies are used in the nth phase period in each of two or more waveform periods before waveform period CY(m) in each overlap period.

[0018] In one exemplary embodiment, the multiple overlapping periods are overlapping periods OP(K a +1)~Overlap Period OP(K b ) where K b is (K a +1). The high frequency power supply is a natural number equal to or greater than the overlap period OP(K a +1)~Overlap Period OP(K b ) are included in each of the waveform periods CY(1) to CY(M b1 ) may perform the above-described initial processing. a +1)~Overlap Period OP(K b ) contained in each waveform period CY(M b1 +1)~Waveform period CY(M b2 ) the pulse-to-pulse feedback may be performed. a +1)~Overlap Period OP(K b ) for each waveform period CY(M b2 ) followed by the intra-pulse feedback. b1 and M a is M b1 <M a may be satisfied.

[0019] In one exemplary embodiment, the RF power source operates during the overlap period OP(K b +1) ~ waveform period CY(1) ~ waveform period CY(M c ) the pulse-to-pulse feedback may be performed. b +1) to the last overlap period, the waveform period CY(M c ) may be followed by the intra-pulse feedback.

[0020] In one exemplary embodiment, the radio frequency generator may be configured to set the source frequency in an nth phase period in a waveform period of the plurality of waveform periods in which intra-pulse feedback is first applied, during at least one overlapping period from the second to the last overlapping period of the plurality of overlapping periods, to the source frequency in the nth phase period in the last waveform period of the plurality of waveform periods included in the overlapping period immediately preceding the at least one overlapping period, or to an average of the source frequencies in the nth phase periods of two or more waveform periods including the last waveform period.

[0021] In one exemplary embodiment, the high frequency power source may be configured to terminate the initial process when a monitor value reflecting the degree of reflection falls within a specified range during the initial process.

[0022] In another exemplary embodiment, a method for controlling a source frequency of source radio frequency power is provided. The method includes (a) applying a pulse of bias energy to a bias electrode of a substrate support disposed within a chamber 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 supplying source radio frequency power from a radio frequency power source to generate a plasma within the chamber. The method further includes setting a source frequency of the source radio frequency power during each of a plurality of phase periods within each of a plurality of waveform periods of the bias energy included in each of a plurality of overlap periods. The plurality of overlap periods overlap each of the plurality of pulse periods. The source frequency f(k,m,n) is adjusted in response to a change in the degree of reflection of the source radio frequency power. The change in the degree of reflection is determined by using a different source frequency during an nth phase period within an mth waveform period in each of two or more overlap periods prior to the kth overlap period among the plurality of overlap periods.

[0023] 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.

[0024] 1 and 2 are diagrams schematically illustrating a plasma processing apparatus according to an exemplary embodiment.

[0025] In one embodiment, the plasma processing system includes a plasma processing device 1 and a controller 2. 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.

[0026] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generating units may be used, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units.

[0027] 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, for example, a computer 2a. The computer 2a may include, for example, 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 operations based on programs stored in the storage unit 2a2. 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).

[0028] An exemplary configuration of a capacitively coupled plasma processing apparatus is described below as an example of the 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. 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 processing 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 sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0029] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 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 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. In one embodiment, the main body 111 includes a base 111e and an electrostatic chuck 111c. The base 111e includes a conductive member. The conductive member of the base 111e functions 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 members, at least one of which is an edge ring. Although not shown, the substrate support 11 may also 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. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0030] 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 a conductive member. The conductive member of the showerhead 13 functions as an 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.

[0031] The gas supply unit 20 may include one or more gas sources 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply one or more process gases from corresponding gas sources 21 to the showerhead 13 via corresponding flow controllers 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 one or more flow modulation devices that modulate or pulse the flow rate of one or more process gases.

[0032] 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.

[0033] The plasma processing apparatus 1 further includes a high-frequency power supply 31 and a bias power supply 32. The plasma processing apparatus 1 may further include a sensor 31s and a control unit 30c.

[0034] The high frequency power supply 31 is configured to generate source high frequency power RF to generate plasma in the chamber (plasma processing chamber 10). The source high frequency power RF has a source frequency of, for example, 13 MHz or more and 150 MHz or less. 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 amplifies the high frequency signal input from the high frequency signal generator 31g to generate the source high frequency power RF and output the source high frequency power RF. The high frequency signal generator 31g may be configured by a programmable processor or a programmable logic device such as an FPGA. A D / A converter may be connected between the high frequency signal generator 31g and the amplifier 31a.

[0035] The high-frequency power supply 31 is connected to the high-frequency electrode via a matching box 31m. In one embodiment, the base 111e constitutes the high-frequency electrode. In another embodiment, the high-frequency electrode may be an electrode provided in the electrostatic chuck 111c. The high-frequency electrode may be a common electrode with a bias electrode, which will be described later. Alternatively, the high-frequency electrode may be an upper electrode. The matching box 31m includes a matching circuit. The matching circuit of the matching box 31m has a variable impedance. The matching circuit of the matching box 31m is controlled by the control unit 30c. The impedance of the matching circuit of the matching box 31m is adjusted so as to match the impedance on the load side of the high-frequency power supply 31 to the output impedance of the high-frequency power supply 31.

[0036] The sensor 31s is configured to output a reflected wave of the source radio frequency power RF returned from the load of the radio frequency power supply 31 to the control unit 30c. The sensor 31s may be connected between the radio frequency power supply 31 and the matching box 31m. The sensor 31s may be connected between the matching box 31m and the radio frequency electrode. For example, the sensor 31s may be connected between the bias electrode and a junction of an electrical path extending from the matching box 31m toward the bias electrode and an electrical path extending from a matching box 32m (described later) toward the bias electrode. Alternatively, the sensor 31s may be connected between the junction and the matching box 31m. The sensor 31s includes, for example, a directional coupler. The directional coupler outputs a reflected wave returned from the load of the radio frequency power supply 31. The reflected wave output from the directional coupler is converted into a digital signal by A / D conversion, and the digitized reflected wave is used in the control unit 30c. The sensor 31s may be a sensor separated from the matching device 31m, or may be a part of the matching device 31m.

[0037] The bias power supply 32 is electrically connected to the bias electrode. In one embodiment, the base 111e constitutes the bias electrode. In another embodiment, the bias electrode may be an electrode provided 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 in each of a plurality of pulse periods PP. The bias power supply 32 may specify the timing of each of the plurality of pulse periods PP by a signal provided from a pulse controller 34. Note that the control unit 2 may function as the pulse controller 34.

[0038] Here, reference is made to Figures 3(a), 3(b), 4(a), and 4(b). Figures 3(a), 3(b), 4(a), and 4(b) are timing charts of examples of source radio frequency power RF and bias energy BE. In these figures, "ON" for source radio frequency power RF indicates that source radio frequency power RF is being supplied, and "OFF" for source radio frequency power RF indicates that the supply of source radio frequency power RF is stopped. Also, in these figures, "ON" for bias energy BE indicates that bias energy BE is being applied to the bias electrode, and "OFF" for bias energy BE indicates that bias energy BE is not being applied to the bias electrode. Also, in these figures, "HIGH" for bias energy BE indicates that bias energy BE having a level higher than the level of bias energy BE indicated by "LOW" is being applied to the bias electrode.

[0039] The multiple pulse periods PP appear sequentially in time. The multiple pulse periods PP may appear sequentially at time intervals (periods) that are the inverse of the pulse frequency. In the following description, pulse period PP(k) represents the kth 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 below, and is, for example, a frequency of 1 kHz or more and 100 kHz or less. As described above, a pulse BEP of bias energy BE is applied to the bias electrode in each of the multiple pulse periods PP. In periods other than the multiple pulse periods PP, bias energy BE does not have to be applied to the bias electrode. Alternatively, bias energy BE having a level lower than the level of bias energy BE in the multiple pulse periods PP may be applied to the bias electrode in periods other than the multiple pulse periods PP.

[0040] As shown in Figure 3(a), the source radio frequency power RF may be supplied as a continuous wave. In the example shown in Figure 3(a), multiple overlapping periods OP in which the source radio frequency power RF is supplied during multiple pulse periods PP each coincide with multiple pulse periods PP.

[0041] Alternatively, as shown in FIGS. 3(b), 4(a), and 4(b), pulses of source radio frequency power RF may be supplied. The radio frequency power source 31 may determine the timing of the period during which pulses of source radio frequency power RF are supplied by a signal provided by the pulse controller 34. As shown in FIG. 3(b), pulses of source radio frequency power RF may be supplied in each of multiple periods that respectively coincide with multiple pulse periods PP. In the example shown in FIG. 3(b), multiple overlap periods OP in which source radio frequency power RF is supplied in the multiple pulse periods PP each coincide with the multiple pulse periods PP. As shown in FIGS. 4(a) and 4(b), pulses of source radio frequency power RF may be supplied in each of multiple periods that partially overlap with the multiple pulse periods PP. In the examples shown in FIGS. 4(a) and 4(b), each of the multiple overlap periods OP in which source radio frequency power RF is supplied in the multiple pulse periods PP is a part of the corresponding pulse period PP among the multiple pulse periods PP. In the following description, overlap period OP(k) represents the kth overlap period among the multiple overlap periods OP. That is, the overlapping period OP(k) represents any overlapping period among the multiple overlapping periods OP.

[0042] Bias energy BE is applied to the bias electrode in each of multiple waveform periods CY within each of multiple pulse periods PP. That is, bias energy BE is applied to the bias electrode periodically within each of multiple pulse periods PP. Each of the multiple waveform periods CY is defined by a bias frequency. The bias frequency is, for example, 50 kHz or more and 27 MHz or less. The time length of each of the multiple waveform periods CY is the reciprocal of the bias frequency. The multiple waveform periods CY appear in temporal order. In the following description, waveform period CY(m) represents the mth waveform period among the multiple waveform periods CY within each of multiple overlap periods OP. Furthermore, waveform period CY(k,m) represents the mth waveform period within the kth overlap period. That is, waveform period CY(m) represents any waveform period among the multiple waveform periods CY.

[0043] Reference is now made to FIGS. 5 and 6. FIG. 5 is a timing chart showing an example of bias energy and the source frequency of the source RF power. FIG. 6 is a timing chart showing another example of bias energy and the source frequency of the source RF power. As shown in FIGS. 5 and 6, in one embodiment, the bias energy BE may be bias RF power having a bias frequency. The bias RF power has a sinusoidal waveform, one cycle of which is a waveform period CY. In this case, as shown in FIG. 2, the bias power supply 32 may include a RF signal generator 32g and an amplifier 32a. The RF signal generator 32g generates a RF signal. The amplifier 32a amplifies the RF signal input from the RF signal generator 32g to generate bias RF power and supplies the generated bias RF power to the bias electrode as bias energy BE. The RF signal generator 32g may be configured from a programmable processor or a programmable logic device such as an FPGA. A D / A converter may be connected between the RF signal generator 32g and the amplifier 32a.

[0044] When the bias energy BE is bias radio frequency power, the bias power supply 32 is connected to the bias electrode via a matching device 32m. The matching device 32m includes a matching circuit. The matching circuit of the matching device 32m has a variable impedance. The matching circuit of the matching device 32m is controlled by the control unit 30c. The impedance of the matching circuit of the matching device 32m is adjusted so as to match the impedance on the load side of the bias power supply 32 to the output impedance of the bias power supply 32.

[0045] FIG. 7 is a timing chart of another example of bias energy. As shown in FIG. 7, in another embodiment, the bias energy BE may include a voltage pulse applied to the bias electrode in each of a plurality of waveform periods CY. The voltage pulse used as the bias energy BE may be a negative voltage pulse as in the example shown in FIG. 7, or may be another voltage pulse. The voltage pulse used as the bias energy BE may have a waveform such as a triangular wave or a square wave. The voltage pulse may also have any other pulse waveform. When a voltage pulse is used as the bias energy BE, a filter that blocks the source radio frequency power RF may be connected between the bias power supply 32 and the bias electrode instead of the matching box 32m shown in FIG. 2.

[0046] The bias power supply 32 is synchronized with the high frequency power supply 31. A synchronization signal used for this purpose may be provided from the bias power supply 32 to the high frequency power supply 31. Alternatively, the synchronization signal may be provided from the high frequency power supply 31 to the bias power supply 32. Alternatively, the synchronization signal may be provided to the high frequency power supply 31 and the bias power supply 32 from another device such as the control unit 30c.

[0047] The control unit 30c is configured to control the high-frequency power supply 31. The control unit 30c may be configured with a processor such as a CPU. The control unit 30c may be part of the matching device 31m, may be part of the high-frequency power supply 31, or may be a control unit separated from the matching device 31m and the high-frequency power supply 31. Alternatively, the control unit 2 may also function as the control unit 30c.

[0048] The control unit 30c is configured to set the source frequency of the source radio frequency power RF in each of the multiple phase periods SP in each of the multiple waveform periods CY included in each of the multiple overlap periods OP. The source frequency of the source radio frequency power RF supplied in periods other than the multiple overlap periods OP may be set using a time series of frequencies registered in a pre-prepared table. The following describes an embodiment in which the control unit 30c sets the source frequency. However, if the control unit 30c is part of the radio frequency power source 31, the radio frequency power source 31 may set the source frequency.

[0049] [Setting the source frequency of the source radio frequency power RF during the overlap period OP(1) to OP(T-1) (intra-pulse feedback)]

[0050] First, the setting of the source frequency of the source radio frequency power RF in the first overlap period OP, i.e., overlap period OP(1), will be described. The control unit 30c is configured to set the source frequency of the source radio frequency power RF in each of the multiple phase periods SP in each of the multiple waveform periods CY in the overlap period OP(1). In the example shown in FIGS. 5 and 6, each of the multiple waveform periods CY in the overlap period OP(1) includes N phase periods SP(1) to SP(N), where N is an integer equal to or greater than 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 may have the same time length or different time lengths. In the following description, phase period SP(n) refers to the nth phase period among phase periods SP(1) to SP(N). In other words, phase period SP(n) refers to any phase period in each of the multiple waveform periods CY in each of the multiple overlap periods OP. Furthermore, phase period SP(m,n) represents the nth phase period in waveform period CY(m), and phase period SP(k,m,n) represents the nth phase period in waveform period CY(m) within kth overlap period OP(k).

[0051] In the overlap period OP(1), the control unit 30c sets the source frequency of the source radio frequency power RF in the phase period SP(m,n) by intra-pulse feedback. For generalization, the following describes intra-pulse feedback applied to the overlap period OP(k). In the case of the overlap period OP(1), k is 1 in the intra-pulse feedback described below.

[0052] In intra-pulse feedback, the control unit 30c adjusts the source frequency of the source radio frequency power RF in the phase period SP(k,m,n) according to changes in the degree of reflection of the source radio frequency power RF. The degree of reflection of the source radio frequency power RF is represented, for example, by the power level Pr of the reflected wave of the source radio frequency power RF output from the sensor 31s. In intra-pulse feedback, changes in the degree of reflection are identified by using different source frequencies of the source radio frequency power RF in corresponding phase periods SP(n) in two or more waveform periods CY prior to the waveform period CY(k,m) within the overlap period OP(k).

[0053] Intra-pulse feedback allows for the use of different source frequencies in the phase periods SP(n) of two or more waveform periods CY, thereby identifying the relationship between a change in source frequency (frequency shift) and a change in the degree of reflection of the source RF power. Therefore, intra-pulse feedback allows for the source frequency used in the phase periods SP(k,m,n) to be adjusted to reduce the degree of reflection in response to changes in the degree of reflection. Intra-pulse feedback also allows for the rapid reduction of the degree of reflection in each of the waveform periods CY in which bias energy BE is applied to the bias electrode of the substrate support 11 during the overlap period OP(k).

[0054] In one embodiment, the two or more waveform periods CY before waveform period CY(k,m) include waveform period CY(k,m-M1) and waveform period CY(k,m-M2), where M1 and M2 are any natural numbers such that M1 > M2. That is, waveform period CY(k,m-M2) is the waveform period after waveform period CY(k,m-M1).

[0055] In one embodiment, the waveform period CY(k,m-M1) may be a waveform period CY(k,m-2Q), and the waveform period CY(k,m-M2) may be a waveform period CY(k,mQ). Note that Q is a natural number. In the example shown in FIG. 5, "Q" and "M2" are "1", and "2Q" and "M1" are "2". "Q" may be an integer equal to or greater than 2.

[0056] In intra-pulse feedback, the control unit 30c applies one frequency shift from the source frequency 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 radio frequency power RF used in the phase period SP(k,m,n). f(k,m,n) is expressed as f(k,m,n) = f(k,m-M2,n) + Δ(k,m,n). Δ(k,m,n) represents the amount of frequency shift. One frequency shift is either a frequency decrease or a frequency increase. If one frequency shift is a frequency decrease, Δ(k,m,n) has a negative value. If one frequency shift is a frequency increase, Δ(k,m,n) has a positive value.

[0057] 5 and 6, the source frequencies in the phase periods SP in the waveform period CY(k,m-M1) are the same and are set to f0, but may be different from each other. Also, in FIG. 5 and 6, the source frequencies in the phase periods SP in the waveform period CY(k,m-M2) are the same and are set to frequencies decreased from frequency f0, but may be increased from frequency f0.

[0058] In intra-pulse feedback, if the degree of reflection is reduced by using a source frequency f(k,m-M2,n) obtained by one frequency shift, the control unit 30c sets the source frequency f(k,m,n) to a frequency having one frequency shift relative to the source frequency f(k,m-M2,n). For example, if the power level Pr(k,m-M2,n) is reduced from the power level Pr(k,m-M1,n) by one frequency shift, the control unit 30c sets the source frequency f(k,m,n) to a frequency having one frequency shift relative to the source frequency f(k,m-M2,n). Note that Pr(k,m,n) represents the power level Pr of the reflected wave of the source radio frequency power RF in the phase period SP(k,m,n).

[0059] In one embodiment, the amount of one frequency shift Δ(m,n) in the phase period SP(k,m,n) may be the same as the amount of one frequency shift Δ(m-M2,n) in the phase period SP(k,m-M2,n). That is, the absolute value of the amount of frequency shift Δ(k,m,n) may 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) may 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) may be set to increase as 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) increases. For example, the absolute value of the amount of frequency shift Δ(k,m,n) may be determined as a function of the degree of reflection (for example, the power level Pr(k,m−M2,n) of the reflected wave).

[0060] In intra-pulse feedback, the degree of reflection may increase when the source frequency f(k,m-M2,n) obtained by one of the frequency shifts is used. 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 one of the frequency shifts. In this case, the control unit 30c may set the source frequency f(k,m,n) to a frequency having the other frequency shift relative to the source frequency f(k,m-M2,n). Note that the source frequency for each phase period SP(n) of two or more waveform periods prior to the waveform period CY(k,m) may be updated to have one of the frequency shifts relative to the source frequency for the phase period SP(n) of the previous waveform period. In this case, if the degree of reflection (e.g., the power level Pr of the reflected wave) or the average value thereof in each of the phase periods SP(n) of the two or more waveform periods is on the rise, the other frequency shift may be imparted to the source frequency in phase period SP(n) of waveform period CY(k,m). For example, the source frequency in phase period SP(n) of waveform period CY(k,m) may be set to a frequency having the other frequency shift relative to the source frequency of the earliest waveform period of the two or more waveform periods.

[0061] Furthermore, in intra-pulse feedback, the degree of reflection may increase when the source frequency f(k,m,n) obtained by one frequency shift is used. For example, one frequency shift may cause the power level Pr(k,m,n) of the reflected wave to increase from the power level Pr(k,m-M2,n). In this case, the control unit 30c may set the source frequency in the phase period SP(n) within the waveform period CY(k,m+M3) to an intermediate frequency. The waveform period CY(k,m+M3) is the period after the waveform period CY(k,m). M3 may be a natural number and may satisfy M3=M2. The intermediate frequency that may be set in the phase period SP(k,m+M3,n) is a frequency between f(k,m-M2,n) and f(k,m,n), and may be the average value of f(k,m-M2,n) and f(k,m,n).

[0062] Furthermore, in intra-pulse feedback, the degree of reflection (e.g., power level Pr) may exceed a predetermined threshold when an intermediate frequency is used in phase period SP(k,m+M3,n). In this case, the control unit 30c may set the source frequency in phase period SP(n) within waveform period CY(k,m+M4) to a frequency having the other frequency shift relative to the intermediate frequency. Waveform period CY(k,m+M4) is the period following waveform period CY(k,m+M3). M4 may be a natural number and may satisfy M4=M1. The threshold is predetermined. The absolute value of the amount of the other frequency shift Δ(1,m+M4,n) is greater than the absolute value of the amount of one frequency shift Δ(1,m,n). In this case, it is possible to prevent the degree of reflection (e.g., power level Pr of the reflected wave) from being unable to decrease from a local minimum value. The threshold values ​​for the respective phase periods SP in each of the waveform periods CY within the overlap period OP(k) may be the same as or different from one another.

[0063] The setting of the source frequency in the overlap period OP(k) (k is 2 or more and T-1 or less, T is an integer 3 or more) will be described below. The source frequencies for the multiple phase periods SP in the multiple waveform periods CY in the overlap period OP(k) may be set by the intra-pulse feedback described above. Note that when setting the source frequencies for the multiple phase periods SP in the waveform period CY(1) in the overlap period OP(k), the waveform periods CY(M-1) and CY(M) in the overlap period OP(k-1) may be used as the waveform periods CY(k,m-M1) and CY(k,m-M2). Note that the waveform period CY(M) is the last waveform period in each overlap period. Furthermore, when setting the source frequency of the source radio frequency power RF for multiple phase periods SP in the waveform period CY(2) within the overlap period OP(k), the waveform period CY(M) within the overlap period OP(k-1) and the waveform period CY(1) within the overlap period OP(k) may be used as the waveform period CY(k,m-M1) and the waveform period CY(k,m-M2).

[0064] In another embodiment, the source frequencies of multiple phase periods SP in multiple waveform periods CY within an overlap period OP(k) (k is 1 or more and T-1 or less, and T is an integer 3 or more) may be set using respective frequencies registered in a pre-prepared table.

[0065] [Setting of source frequency of source radio frequency power RF during overlap periods after overlap period OP(T) (pulse-to-pulse feedback)]

[0066] Setting of the source frequency of the source radio frequency power RF in the Tth (T is an integer equal to or greater than 3) overlap period OP(k) will be described below with reference to Fig. 8. Fig. 8 is a timing chart showing an example of the bias energy and the source frequency of the source radio frequency power.

[0067] The control unit 30c is configured to set the source frequency of the source radio frequency power RF in each of the multiple phase periods SP in each of the multiple waveform periods CY included in each of the multiple overlap periods OP after the second overlap period by pulse-to-pulse feedback.

[0068] In inter-pulse feedback, the control unit 30c adjusts the source frequency f(k,m,n) in accordance with changes in the degree of reflection of the source high frequency power RF. The degree of reflection of the source high frequency power RF is represented, for example, 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, changes in the degree of reflection are identified by using different source frequencies of the source high frequency power RF in corresponding phase periods SP(n) in waveform periods CY(m) in two or more overlap periods OP prior to the overlap period OP(k).

[0069] Inter-pulse feedback allows for the use of different source frequencies in the same phase period within the same waveform cycle in each of two or more overlap periods OP, thereby identifying the relationship between a change in source frequency (frequency shift) and a change in the degree of reflection of the source RF power. Therefore, inter-pulse feedback allows for the source frequency used in phase period SP(k,m,n) to be adjusted to reduce the degree of reflection in response to changes in the degree of reflection. Furthermore, intra-pulse feedback allows for the rapid reduction of the degree of reflection in each of multiple waveform periods CY within each of multiple overlap periods OP.

[0070] In one embodiment, the two or more overlapping periods OP before 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), where K1 and K2 are natural numbers satisfying K1>K2.

[0071] 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 after the overlap period OP(k-K1), which is the overlap period OP(k-1) in one embodiment. That is, in one embodiment, K2 and K1 are 1 and 2, respectively.

[0072] The control unit 30c applies one frequency shift from the source frequency in phase period SP(k-K1,m,n) to the source frequency f(k-K2,m,n) in phase period SP(k-K2,m,n). Here, f(k,m,n) represents the source frequency of the source radio frequency power RF used in phase period SP(k,m,n). f(k,m,n) is expressed as f(k,m,n)=f(k-K2,m,n)+Δ(k,m,n). Δ(k,m,n) represents the amount of frequency shift. One frequency shift is either a frequency decrease or a frequency increase. If one frequency shift is a frequency decrease, Δ(k,m,n) has a negative value. If one frequency shift is a frequency increase, Δ(k,m,n) has a positive value.

[0073] In FIG. 8, the source frequencies in the multiple phase periods SP within the waveform cycle CY(2,1) are the same and are set to frequencies decreased from frequency f0, but may also be increased from frequency f0.

[0074] In pulse-to-pulse feedback, if the degree of reflection decreases when using a source frequency f(k-K2,m,n) obtained by one frequency shift, the control unit 30c sets the source frequency f(k,m,n) to a frequency having one frequency shift relative to the source frequency f(k-K2,m,n). For example, if the power level Pr(k-K2,m,n) decreases from the power level Pr(k-K1,m,n) due to one frequency shift, the control unit 30c sets the source frequency f(k,m,n) to a frequency having one frequency shift relative to the source frequency f(k-K2,m,n). Note that Pr(k,m,n) represents the power level Pr of the reflected wave of the source radio frequency power RF in the phase period SP(k,m,n). Note that the source frequency of each phase period SP(m,n) of two or more overlap periods before the overlap period OP(k) may be updated to have one frequency shift relative to the source frequency of the phase period SP(m,n) of the previous overlap period. In this case, if the degree of reflection (e.g., the power level Pr of the reflected wave) or the average value thereof in each of the phase periods SP(m,n) of the two or more overlap periods is on the rise, the source frequency of the phase period SP(m,n) of the overlap period OP(k) may be given the other frequency shift. For example, the source frequency of the phase period SP(m,n) of the overlap period OP(k) may be set to a frequency having the other frequency shift relative to the source frequency of the earliest overlap period among the two or more overlap periods.

[0075] In one embodiment, the amount of one frequency shift Δ(m,n) in the phase period SP(k,m,n) may be the same as the amount of one frequency shift Δ(k-K2,m,n) in the phase period SP(k-K2,m,n). That is, the absolute value of the amount of frequency shift Δ(k,m,n) may 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) may 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) may be set to increase as 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) increases. For example, the absolute value of the amount of frequency shift Δ(k, m, n) may be determined as a function of the degree of reflection (power level Pr(k−1, m, n) of the reflected wave).

[0076] In pulse-to-pulse feedback, the degree of reflection may increase when the source frequency f(k-K2,m,n) obtained by one of the frequency shifts is used. 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 one of the frequency shifts. In this case, the control unit 30c may set the source frequency f(k,m,n) to a frequency having the other frequency shift relative to the source frequency f(k-K2,m,n).

[0077] Furthermore, in pulse-to-pulse feedback, when a source frequency f(k,m,n) obtained by one frequency shift is used, the degree of reflection may increase. For example, one frequency shift may cause the power level Pr(k,m,n) of the reflected wave to increase from the power level Pr(k-K2,m,n). In this case, the control unit 30c may 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) may be set to an intermediate frequency. The overlap period OP(k+K3) is the period after the overlap period OP(k). K3 may be a natural number, and may satisfy K3=K2. The intermediate frequency that can be set in phase period SP(k+K3,m,n) is a frequency between f(k-K2,m,n) and f(k,m,n), and may be the average value of f(k-K2,m,n) and f(k,m,n).

[0078] Furthermore, in pulse-to-pulse feedback, the degree of reflection (e.g., power level Pr) may exceed a predetermined threshold when the intermediate frequency is used in the phase period SP(k+K3,m,n). In this case, the control unit 30c may set the source frequency in the phase period SP(k+K4,m,n) to a frequency having the other frequency shift relative to the intermediate frequency. That is, in this case, the other frequency shift may 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 and may also satisfy K4=K1. The threshold is predetermined. The absolute value of the amount of the other frequency shift Δ(k+K4,m,n) is greater than the absolute value of the amount of one frequency shift Δ(k,m,n). In this case, it is possible to avoid the situation where the degree of reflection (for example, the power level Pr of the reflected wave) cannot be reduced from a local minimum value. Note that the thresholds for the multiple phase periods SP in each of the multiple waveform periods CY within the multiple overlap periods OP may be the same as or different from each other.

[0079] The plasma processing apparatus 1 may use a representative value of the measurements for each phase period as the degree of reflection for that phase period. The representative value may be the average or maximum value of the measurements for that phase period. The plasma processing apparatus 1 may also use at least one of the above-mentioned reflected wave power level Pr, the ratio of the reflected wave power level Pr to the output power level of the source high frequency power RF (hereinafter referred to as "reflectivity"), the phase difference θ between the voltage V and the current I, and the load-side impedance Z of the high frequency power supply 31 as the measurement value.

[0080] The plasma processing apparatus 1 may include a VI sensor in addition to or instead of the sensor 31s. The VI sensor measures the voltage V and current I in the power supply path of the source radio frequency power RF between the radio frequency power supply 31 and the radio frequency electrode. The VI sensor may be connected between the radio frequency power supply 31 and the matching box 31m. The VI sensor may be connected between the matching box 31m and the radio frequency electrode. For example, the VI sensor may be connected between the bias electrode and a junction of an electrical path extending from the matching box 31m toward the bias electrode and an electrical path extending from the matching box 32m toward the bias electrode. Alternatively, the VI sensor may be connected between the junction and the matching box 31m. The VI sensor may be part of the matching box 31m.

[0081] The source frequency for each of the multiple phase periods SP of each waveform cycle CY may be changed according to the voltage V, the current I, and the phase difference θ between the voltage V and the current I so as to bring the impedance on the load side of the high frequency power supply 31 closer to the matching point. Also, the variable impedance of the matching box 31m may be adjusted according to the voltage V, the current I, and the phase difference θ so as to bring the impedance Z on the load side of the high frequency power supply 31 closer to the matching point. Note that 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°.

[0082] A method for controlling the source frequency of source radio frequency power according to one exemplary embodiment will now be described with reference to FIG. 9. FIG. 9 is a flowchart of a method for controlling the source frequency of source radio frequency power according to one exemplary embodiment. The method MT shown in FIG. 9 starts with step STa or step STb. In step STa, a pulse BEP of bias energy BE is applied to a bias electrode of a substrate support 11 of a plasma processing apparatus 1. The pulse BEP of bias energy BE is applied to the bias electrode in each of a plurality of pulse periods PP.

[0083] In step STb, a source radio frequency power RF is supplied from a radio frequency power supply (e.g., radio frequency power supply 31) to generate plasma in the chamber. The source radio frequency power RF is supplied as shown in FIGS. 3(a), 3(b), 4(a), and 4(b).

[0084] In step STc, the source frequency of the source radio frequency power RF used in each of the multiple phase periods SP in each of the multiple waveform periods CY included in each of the multiple overlap periods OP is set. In inter-pulse feedback, the source frequency in the phase periods SP(k,m,n) in the waveform period CY(m) within the overlap period OP(k) is adjusted in response to changes in the degree of reflection of the source radio frequency power. In inter-pulse feedback, changes in the degree of reflection (e.g., the power level Pr of the reflected wave) are identified by using different source frequencies in the corresponding phase periods SP(n) in the waveform period CY(m) in each of two or more overlap periods before the overlap period OP(k). See the above description for details of inter-pulse feedback.

[0085] Hereinafter, reference will be made to (a) to (d) of FIG. 10. Each of (a) to (d) of FIG. 10 is a timing chart of yet another example of bias energy. In one embodiment, the multiple overlap periods OP are divided into 1 to K a The overlapping period OP(1)~OP(K a ) where K a is a natural number greater than or equal to 2.

[0086] The high frequency power supply 31 operates during the overlapping periods OP(1) to OP(K a ) the first to Mth waveform periods CY included in each of a The waveform period CY(1)~CY(M a ) may be initialized. a is a natural number. In the initial processing, the waveform periods CY(1) to CY(M a ) may be used, and the frequency sets included in the frequency set group may be different from each other. a ) may be used, and these frequency set groups may be different from each other. Note that the frequency sets and frequency set groups may be stored in a storage unit of the control unit 2 or the control unit 30c.

[0087] The high frequency power supply 31 operates during the overlapping periods OP(1) to OP(K a ), among the plurality of waveform periods CY, a ), the above-mentioned intra-pulse feedback may be performed after the overlapping periods OP(1) to OP(K). a ) contained in each waveform period CY(M a +1) to CY(M), the above-mentioned intra-pulse feedback may be performed.

[0088] In one embodiment, the multiple overlapping periods OP are (K a +1) to K b th overlap period OP(K a +1)~OP(K b ) where K b is (K a +1), and K b =K a +1 may be met.

[0089] The high frequency power supply 31 operates during the overlap period OP(Ka +1)~OP(K b ) the first to Mth waveform periods CY included in each of b1 The waveform period CY(1)~CY(M b1 ) may be subjected to the above initial processing. b1 is a natural number. M b1 and M a is M b1 <M a may be satisfied.

[0090] The high frequency power supply 31 operates during the overlap period OP(K a +1)~OP(K b ) among the multiple waveform periods CY included in each of (M b1 +1)th to M b2 th waveform period CY(M b1 +1)~CY(M b2 ), the pulse-to-pulse feedback may be performed. b2 is M b2 >M b1 is a natural number that satisfies

[0091] The high frequency power supply 31 operates during the overlap period OP(K a +1)~OP(K b ) for each waveform period CY(M b2 ), the above-mentioned intra-pulse feedback may be performed after the overlap period OP(K a +1)~OP(K b ) contained in each waveform period CY(M b2 +1) to CY(M), the above-mentioned intra-pulse feedback may be performed.

[0092] The high frequency power supply 31 is (K b +1)th to last overlapping period OP(K b +1) to OP(K) c The waveform period CY(1)~CY(M c ), the pulse-to-pulse feedback may be performed. cis a natural number. The high frequency power supply 31 operates during the overlap period OP(K b +1) to OP(K), the waveform period CY(M c ), the above-mentioned intra-pulse feedback may be performed after the overlap period OP(K b +1) to OP(K) c +1) to CY(M), the above-mentioned intra-pulse feedback may be performed.

[0093] In one embodiment, the high frequency power supply 31 generates a waveform period CY(M F The source frequency in a phase period SP(n) in the waveform period CY(M) may be set to the source frequency in the same phase period SP(n) in the last waveform period CY(M) included in the overlap period immediately preceding the at least one overlap period. F ) is a waveform period to which intra-pulse feedback is first applied among the multiple waveform periods CY in the at least one overlap period. Alternatively, the high frequency power supply 31 may apply the waveform period CY(M F The source frequency in a phase period SP(n) in the at least one overlap period may be set to the average value of the source frequencies in the same phase period SP(n) of two or more waveform periods including the last waveform period CY(M) included in the overlap period immediately preceding the at least one overlap period. The two or more waveform periods may be the waveform period CY(M) included in the overlap period immediately preceding the at least one overlap period. L +1) to CY(M), where M L is the number of the two or more waveform periods.

[0094] In one embodiment, the above-mentioned M a , M b1 , M b2 , and M c Each of the parameters may be a preset value, i.e., M a and M b1, and M, the number of waveform periods over which pulse-to-pulse feedback is applied. b2 and M c may be preset.

[0095] Alternatively, the RF power supply 31 may be configured to terminate the initial process when a monitor value reflecting the degree of reflection falls within a specified range during the initial process, or when a monitor value reflecting the degree of reflection falls within a specified range during inter-pulse feedback.

[0096] One or more measured values ​​may be used as the monitor value. Alternatively, the amount of change (rate of change or difference) between waveform periods of the average value of each of one or more measured values ​​in the same phase period may be used as the monitor value. Alternatively, the amount of change over time (rate of change or difference) between waveform periods of the average value of each of one or more measured values ​​in the same phase period for several waveform periods may be used as the monitor value. Alternatively, the amount of change (rate of change or difference) between waveform periods of the average value of each of one or more measured values ​​in the same phase period may be used as the monitor value. Alternatively, the variation in one or more waveform periods of each of one or more measured values ​​or the variation in several waveform periods of each of one or more measured values ​​in the same phase period may be used as the monitor value. The one or more measured values ​​may include one or more of the power level Pr of the reflected wave, the reflectance described above, the phase difference θ between the voltage V and the current I, the impedance Z, the peak-to-peak voltage Vpp (Vpp) of the bias electrode, the self-bias voltage Vdc of the bias electrode, and the light-emitting state of the plasma.

[0097] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0098] As described above, in other embodiments, the plasma processing apparatus may be an inductively coupled plasma processing apparatus, an ECR plasma processing apparatus, a helicon wave excited plasma processing apparatus, or a surface wave plasma processing apparatus. In any of these plasma processing apparatuses, source radio frequency power RF is used to generate the plasma, and the source frequency used in the multiple phase periods SP of the multiple waveform periods CY is adjusted as described above with respect to the plasma processing apparatus 1.

[0099] Furthermore, in intra-pulse feedback, the source frequency of the source radio frequency power RF in the phase period SP(k,m,n) may be determined as the frequency that minimizes the degree of reflection from two or more degrees of reflection (e.g., power levels Pr) obtained by using different source frequencies of the source radio frequency power RF in corresponding phase periods SP(n) in two or more waveform periods CY prior to the waveform period CY(k,m) within the overlap period OP(k). The frequency that minimizes the degree of reflection may be determined by a least squares method using each of the different frequencies and the corresponding degrees of reflection.

[0100] In addition, in inter-pulse feedback, the source frequency f(k,m,n) may be determined as the frequency that minimizes the degree of reflection from two or more degrees of reflection (e.g., power levels Pr) obtained by using different source frequencies of source radio frequency power RF in corresponding phase periods SP(n) in waveform periods CY(m) within two or more overlap periods OP before the overlap period OP(k). The frequency that minimizes the degree of reflection may be determined by a least-squares method using each of the different frequencies and the corresponding degrees of reflection.

[0101] The present disclosure also includes the following further embodiments E1 to E9. [E1] a chamber; a substrate support provided within the chamber and having a bias electrode; a radio frequency power source configured to generate radio frequency power to generate a plasma within the chamber; a bias power supply configured to provide a pulse of bias energy to the bias electrode during each of a plurality of pulse periods; a sensor configured to output a reflected wave of the high frequency power returned from a load of the high frequency power supply; a control unit configured to control the high frequency power source; Equipped with the bias power supply is configured to provide the bias energy to the bias electrode during each of a plurality of periods within each of the plurality of pulse periods; The control unit a frequency of the high frequency power in each of a plurality of phase periods in each of a plurality of cycles included in each of a plurality of overlap periods, which are periods during which the high frequency power is supplied in the plurality of pulse periods; a frequency of the high frequency power in an n-th phase period in an m-th cycle in a k-th overlap period among the plurality of overlap periods is adjusted in accordance with a change in the power level of the reflected wave output from the sensor when different frequencies of the high frequency power are used in corresponding phase periods in the m-th cycle in each of two or more overlap periods before the k-th overlap period among the plurality of overlap periods. Plasma processing equipment. [E2] the two or more overlapping periods include a first overlapping period and a second overlapping period that follows the first overlapping period; The plasma processing apparatus of embodiment E1, wherein the control unit is configured, when the power level of the reflected wave is reduced by imparting a frequency shift of either a decrease or an increase to the frequency of the high frequency power in the nth phase period in the mth period within the second overlap period from the frequency of the high frequency power in the nth phase period in the mth period within the first overlap period, to set the frequency of the high frequency power in the nth phase period in the mth period within the kth overlap period to a frequency having the one of the frequency shifts relative to the frequency of the high frequency power in the nth phase period in the mth period within the second overlap period. [E3] the control unit is configured to set the frequency of the high frequency power in the n-th phase period in the m-th cycle within the k-th overlap period to the frequency having the one frequency shift with respect to the frequency of the high frequency power in the n-th phase period in the m-th cycle within the second overlap period, so that when the power level of the reflected wave increases, the control unit is configured to set the frequency of the high frequency power in the n-th phase period in the m-th cycle within a third overlap period after the k-th overlap period among the multiple overlap periods to an intermediate frequency between the frequency of the high frequency power in the n-th phase period in the m-th cycle within the second overlap period and the frequency of the high frequency power in the n-th phase period in the m-th cycle within the k-th overlap period. The plasma processing apparatus of embodiment E2. [E4] The plasma processing apparatus of embodiment E3, wherein the control unit is configured to set the frequency of the high-frequency power in the n-th phase period in the m-th period within a fourth overlap period after the third overlap period among the multiple overlap periods to a frequency having another frequency shift with an absolute value greater than the absolute value of one of the frequency shift amounts relative to the intermediate frequency when the power level of the reflected wave is greater than a threshold value in the n-th phase period within the m-th period within the third overlap period. [E5] A plasma processing apparatus of embodiment E2, wherein the absolute value of the amount of one of the frequency shifts of the frequency of the high frequency power in the nth phase period in the mth cycle within the kth overlap period is greater than the absolute value of the amount of one of the frequency shifts of the frequency of the high frequency power in the nth phase period in the mth cycle within the second overlap period. [E6] the two or more overlapping periods include a first overlapping period and a second overlapping period that follows the first overlapping period; the control unit is configured, when the power level of the reflected wave increases by imparting one of a decrease and an increase in frequency shift from the frequency of the high frequency power in the n-th phase period in the m-th cycle within the first overlapping period to the frequency of the high frequency power in the n-th phase period in the m-th cycle within the second overlapping period, to set the frequency of the high frequency power in the n-th phase period in the m-th cycle within the k-th overlapping period to a frequency having the other frequency shift with respect to the frequency of the high frequency power in the n-th phase period in the m-th cycle within the second overlapping period. The plasma processing apparatus of embodiment E1. [E7] A plasma processing apparatus according to any one of embodiments E1 to E6, wherein the bias energy is high-frequency power having a bias frequency that defines the plurality of periods, or includes a voltage pulse applied to the bias electrode in each of the plurality of periods defined by the bias frequency. [E8] A method for controlling the frequency of radio frequency power, comprising: applying a pulse of bias energy to a bias electrode of a substrate support disposed within a chamber of a plasma processing apparatus during each of a plurality of pulse periods, the pulse of bias energy including bias energy applied to the bias electrode during each of a plurality of periods within each of the plurality of pulse periods; providing the radio frequency power from a radio frequency power source to generate a plasma in the chamber; setting a frequency of the high frequency power in each of a plurality of phase periods in each of a plurality of cycles included in each of a plurality of overlap periods, which are periods during which the high frequency power is supplied in the plurality of pulse periods; Including, A method in which the frequency of the high-frequency power in the n-th phase period in the m-th cycle within the k-th overlapping period among the plurality of overlapping periods is adjusted according to a change in the power level of the reflected wave of the high-frequency power when different frequencies of the high-frequency power are used in corresponding phase periods within the m-th cycle in each of two or more overlapping periods prior to the k-th overlapping period among the plurality of overlapping periods.

[0102] 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]

[0103] 1...plasma processing apparatus, 10...plasma processing chamber, 11...substrate support portion, 31...high frequency power supply, 32...bias power supply, 31s...sensor, 30c...control portion.

Claims

1. A plasma processing chamber; a substrate support disposed within the plasma processing chamber; a bias electrode provided within the substrate support; a first radio frequency power source coupled to the plasma processing chamber and configured to generate a first radio frequency power, the first radio frequency power including a plurality of periodically repeated first states; a bias power supply configured to provide bias energy to the bias electrode, the bias energy including a plurality of periodically repeated second states, the plurality of second states having a plurality of overlapping periods that respectively overlap with the plurality of first states, each of the plurality of overlapping periods having a plurality of cycles; a sensor configured to output a parameter related to at least one degree of reflection in a power supply path of the first high frequency power; A control unit; Equipped with The control unit a frequency of the first high frequency power is set in each of a plurality of periods within each cycle of the bias energy; The frequency in an n-th period in an m-th cycle among the plurality of cycles in a k-th overlapping period among the plurality of overlapping periods is adjusted based on an output of the sensor in an n-th period in the m-th cycle among the plurality of cycles in one or more overlapping periods before the k-th overlapping period among the plurality of overlapping periods. Plasma processing equipment.

2. A plasma processing apparatus as described in claim 1, wherein the sensor is a directional coupler configured to output a reflected wave returned from a load of the first high-frequency power supply.

3. The plasma processing apparatus described in claim 1, wherein the sensor is a VI sensor configured to measure the voltage and current in the power supply path of the first high-frequency power.

4. A plasma processing apparatus as described in claim 1, wherein the at least one parameter related to the degree of reflection includes at least one of the power level of the reflected wave of the first high-frequency power, the ratio of the power level of the reflected wave to the output power level of the first high-frequency power, the phase difference θ between the voltage and current of the first high-frequency power, and the impedance on the load side of the first high-frequency power source.

5. A plasma processing apparatus described in any one of claims 1 to 4, wherein the first high-frequency power has multiple frequency components simultaneously in one or more cycles prior to the mth cycle.

6. A plasma processing apparatus described in any one of claims 1 to 4, wherein the first high-frequency power has a frequency that is different from each other in two or more cycles prior to the mth cycle.

7. A plasma processing apparatus as described in claim 1, wherein the bias energy has a second high-frequency power.

8. The plasma processing apparatus of claim 1, wherein the bias energy comprises a voltage pulse.

9. A plasma processing apparatus as described in any one of claims 1 to 8, wherein the multiple periods in each of the multiple cycles have the same number and length across the multiple cycles.

10. A plasma processing apparatus described in any one of claims 1 to 9, wherein the first high-frequency power has a frequency of 13 MHz to 150 MHz, and the multiple cycles are defined by a frequency of 50 kHz to 27 MHz.

11. A plasma processing chamber; a substrate support disposed within the plasma processing chamber; a bias electrode provided within the substrate support; a first radio frequency power source coupled to the plasma processing chamber and configured to generate a first radio frequency power; a second radio frequency power source configured to apply a second radio frequency power having a plurality of cycles to the bias electrode; a sensor configured to output at least one parameter of the first high frequency power supply line; a control unit configured to individually set the frequency of the first high frequency power for each of a plurality of periods within each cycle of the second high frequency power based on the output of the sensor; A plasma processing apparatus comprising:

12. A plasma processing apparatus as described in claim 11, wherein the sensor is a directional coupler configured to output a reflected wave returned from a load of the first high-frequency power supply.

13. A plasma processing apparatus as described in claim 11, wherein the sensor is a VI sensor configured to measure the voltage and current in the power supply path of the first high frequency power.

14. A plasma processing apparatus as described in claim 11, wherein the at least one parameter includes at least one of the power level of the reflected wave of the first high-frequency power, the ratio of the power level of the reflected wave to the output power level of the first high-frequency power, the phase difference θ between the voltage and current of the first high-frequency power, and the impedance on the load side of the first high-frequency power source.

15. A plasma processing apparatus described in any one of claims 11 to 14, wherein the first high-frequency power has a frequency of 13 MHz to 150 MHz, and the multiple cycles are defined by a frequency of 50 kHz to 27 MHz.

16. A plasma processing chamber; a substrate support disposed within the plasma processing chamber; a bias electrode provided within the substrate support; a radio frequency power source coupled to the plasma processing chamber and configured to generate radio frequency power; a voltage pulse generator configured to apply a voltage pulse signal having a plurality of cycles to the bias electrode; a sensor configured to output at least one parameter of the high frequency power supply line; a control unit configured to individually set the frequency of the high frequency power in each of a plurality of periods within each cycle of the voltage pulse signal based on an output of the sensor; A plasma processing apparatus comprising:

17. A plasma processing apparatus as described in Claim 16, wherein the sensor is a directional coupler configured to output a reflected wave returned from a load of the high-frequency power supply.

18. A plasma processing apparatus as described in claim 16, wherein the sensor is a VI sensor configured to measure the voltage and current in the power supply path of the high-frequency power.

19. A plasma processing apparatus as described in claim 16, wherein the at least one parameter includes at least one of the power level of the reflected wave of the high-frequency power, the ratio of the power level of the reflected wave to the output power level of the high-frequency power, the phase difference θ between the voltage and current of the high-frequency power, and the impedance on the load side of the high-frequency power source.

20. A plasma processing apparatus described in any one of claims 16 to 19, wherein the high-frequency power has a frequency of 13 MHz to 150 MHz, and the multiple cycles are defined by a frequency of 50 kHz to 27 MHz.

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