Plasma processing apparatus and matching method

Abstract

A technique capable of reducing reflection from a load after switching of electric power supplied to an electrode of a plasma processing apparatus from one of a modulated wave and a continuous wave of high-frequency electric power to the other is provided. A plasma processing apparatus of one example embodiment includes a chamber, a high-frequency power source, an electrode, and a matcher. The high-frequency power source is electrically connected to the electrode. The matcher is connected between the high-frequency power source and the electrode. The high-frequency power source supplies a continuous wave and a modulated wave of high-frequency electric power to the electrode. The modulated wave is generated by alternately increasing and decreasing a power level of the high-frequency electric power. The matcher stepwise changes a load impedance to a target impedance during a period in which the continuous wave is supplied before or after the electric power supplied from the high-frequency power source to the electrode is switched from one of the modulated wave and the continuous wave to the other.

Description

TECHNICAL FIELD

[0001] An example embodiment of the present application relates to a plasma processing apparatus and a matching method. BACKGROUND

[0002] In the manufacture of electronic devices, a plasma processing apparatus is used. The plasma processing apparatus includes a chamber, an electrode, a high-frequency power source, and a matcher. In order to excite a gas in the chamber to generate plasma, high-frequency electric power can be applied from the high-frequency power source to the electrode. The matcher can match the impedance on the load side of the high-frequency power source, i.e., the load impedance, to the output impedance of the high-frequency power source.

[0003] A technique has been proposed in which, in a plasma processing apparatus, a high-frequency electric power whose power is alternately increased and decreased, i.e., a modulation wave of high-frequency electric power, is supplied to an electrode. This technique is described in, for example, Patent Documents 1 and 2 below.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-90770

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-186099 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] The present application provides a technique that reduces reflection from a load after switching electric power supplied to an electrode of a plasma processing apparatus from one of a modulation wave and a continuous wave of high-frequency electric power to the other.

[0010] MEANS OF SOLVING THE PROBLEMS

[0011] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, electrodes, a high-frequency power supply, and a matching device. The high-frequency power supply is electrically connected to the electrodes. The high-frequency power supply is configured to generate high-frequency electrical power to be supplied to the electrodes for plasma processing within the chamber. The matching device is connected between the high-frequency power supply and the electrodes. The matching device is configured to set a load impedance that serves as the load side impedance of the high-frequency power supply. The high-frequency power supply is configured to supply a power wave of either a modulated wave or a continuous wave to the electrodes in an earlier period of two consecutive periods, and to supply the other power wave of either the modulated wave or the continuous wave to the electrodes in a later period of the two consecutive periods. The high-frequency power supply generates the modulated wave in an alternating manner, such that the power level of the high-frequency electrical power in the first period is higher than the power level of the high-frequency electrical power in the second period. The matching device is configured to stepwise change the load impedance to a target impedance for the later period during the period of supplying the continuous wave in the two consecutive periods.

[0012] Invention Effects

[0013] According to one exemplary embodiment, it is possible to reduce reflections from the load after switching the electrical power supplied to the electrodes of the plasma processing device from one of a modulated wave and a continuous wave of high-frequency electrical power to the other. Attached Figure Description

[0014] Figure 1 This is a diagram that schematically illustrates a plasma processing apparatus of an exemplary embodiment.

[0015] Figure 2 This is an example of a timing diagram representing the first high-frequency electrical power and the second high-frequency electrical power.

[0016] Figure 3 This is another example of a timing diagram representing the first high-frequency electrical power and the second high-frequency electrical power.

[0017] Figure 4 This is an example Figure 1 A diagram showing an example of the structure of the first high-frequency power supply and the first matcher of the plasma processing apparatus.

[0018] Figure 5 It means Figure 1 A diagram showing an example of the structure of the sensor of the first matcher in the plasma processing device.

[0019] Figure 6 It means Figure 1 A diagram showing an example of the structure of the second high-frequency power supply and the second matching unit of the plasma processing device.

[0020] Figure 7 It meansFigure 1 FIG. 1 is a diagram showing an example of a sensor structure of a second matcher of a plasma processing apparatus.

[0021] Figure 8 FIG. 2 is a diagram showing an example of a change in an absolute value of a reflection coefficient.

[0022] Figure 9 FIG. 3 is a diagram showing another example of a change in an absolute value of a reflection coefficient.

[0023] Figure 10 FIG. 4 is a flowchart of a matching method of an example embodiment.

[0024] LEGEND

[0025] 1... plasma processing apparatus, 10... chamber, 16... susceptor, 36... high-frequency power supply, 38... high-frequency power supply, 40... matcher, 42... matcher. DETAILED DESCRIPTION

[0026] Hereinafter, various example embodiments will be described.

[0027] In one example embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, an electrode, a high-frequency power supply, and a matcher. The high-frequency power supply is electrically connected to the electrode. The high-frequency power supply is configured to be able to generate high-frequency electric power to be supplied to the electrode for plasma processing in the chamber. The matcher is connected between the high-frequency power supply and the electrode. The matcher is configured to be able to set a load impedance that is an impedance on a load side of the high-frequency power supply. The high-frequency power supply is configured to be able to supply, to the electrode, a power wave of one of a continuous wave and a modulated wave in an earlier period of two consecutive periods, and a power wave of the other of the continuous wave and the modulated wave in a later period of the two consecutive periods. The high-frequency power supply generates the modulated wave in such a manner that a power level of the high-frequency electric power in a first sub-period of first and second sub-periods is higher than a power level of the high-frequency electric power in the second sub-period. The matcher is configured to be able to stepwise change the load impedance to a target impedance for the later period in the period in which the continuous wave is supplied of the two consecutive periods.

[0028] In the above-described embodiment, the matcher stepwise changes the load impedance to the target impedance for the later period in the period in which the continuous wave is supplied before or after the electric power supplied from the high-frequency power supply to the electrode is switched from the power wave of one to the power wave of the other. Therefore, the matcher is able to track the load impedance to be set after the electric power supplied from the high-frequency power supply to the electrode is switched from the power wave of one to the power wave of the other. Therefore, it is possible to reduce the reflection after the electric power supplied from the high-frequency power supply to the electrode is switched from one of the modulated wave and the continuous wave to the other.

[0029] In one illustrative embodiment, the matching device can be configured to change the step of the load impedance during the period in which the high-frequency electric power is supplied as the continuous wave so that the absolute value of the reflection coefficient of the high-frequency electric power changes stepwise to a set target value for the subsequent period.

[0030] In one illustrative embodiment, the matching device can be configured to change the step of the load impedance after the electric power supplied from the high-frequency power source to the electrode is switched from the modulated wave to the continuous wave so that the absolute value of the reflection coefficient of the high-frequency electric power decreases stepwise to zero.

[0031] In one illustrative embodiment, the matching device can be configured to change the step of the load impedance before the electric power supplied to the electrode is switched from the continuous wave to the modulated wave so that the absolute value of the reflection coefficient of the high-frequency electric power increases stepwise to a set target value that is greater than zero. The set target value can be 0.3 or more and 0.5 or less.

[0032] In one illustrative embodiment, the matching device can be configured to change the step of the load impedance during the period in which the high-frequency electric power is supplied as the continuous wave so that the absolute value of the reflection coefficient of the high-frequency electric power changes stepwise to a set target value for the subsequent period. The length of each of the plurality of sub-periods can be set to 0.5 seconds or more, and the difference between the target value of the absolute value of the reflection coefficient in one of any two consecutive sub-periods included in the plurality of sub-periods and the target value of the absolute value of the reflection coefficient in the other sub-period can be set to 0.2 or less. Alternatively, the length can be set to 0.2 seconds or more, and the difference can be set to 0.1 or less. Alternatively, the length can be set to 0.5 seconds or more, and the difference can be set to 0.05 or less.

[0033] In one illustrative embodiment, the matching device can be configured to adjust the load impedance of the high-frequency power source in the period in which the modulated wave is supplied among the two consecutive periods to a target impedance that is different from the output impedance of the high-frequency power source. The load impedance of the high-frequency power source can be determined from the measured value of the load impedance in the monitoring period within the first sub-period. According to this embodiment, the reflection from the load to the modulated wave can be reduced in the period in which the modulated wave is supplied.

[0034] In one illustrative embodiment, the monitoring period can be a period that starts after a prescribed length of time has elapsed from the start time of the first sub-period.

[0035] In one illustrative embodiment, the matching device can be configured to determine the target impedance in accordance with a set target value of the absolute value of the reflection coefficient of the modulated wave in the period in which the modulated wave is supplied. In one illustrative embodiment, the set target value can be 0.3 or more and 0.5 or less.

[0036] In one example embodiment, the high-frequency power source can also be configured to adjust a power level of the high-frequency electric power so that a load power level during a period in which the modulated wave is supplied approaches or coincides with a target power level. The load power level is a difference between a power level of a forward wave of the modulated wave and a power level of a reflected wave of the modulated wave. Reflection occurs when the target impedance is different from an output impedance of the high-frequency power source. According to this embodiment, the modulated wave of the target power level can be coupled to the plasma even if reflection occurs.

[0037] In another example embodiment, a matching method is provided. The matching method is executed in a plasma processing apparatus. The plasma processing apparatus includes a chamber, an electrode, a high-frequency power source, and a matcher. The high-frequency power source is electrically connected to the electrode. The high-frequency power source is configured to generate high-frequency electric power to be supplied to the electrode for plasma processing in the chamber. The matcher is connected between the high-frequency power source and the electrode and is configured to set a load impedance as an impedance on a load side of the high-frequency power source. The matching method includes a step of supplying, by the high-frequency power source, a power wave of one of a modulated wave and a continuous wave of the high-frequency electric power to the electrode in an earlier period of two consecutive periods. The modulated wave is generated in such a manner that a power level of the high-frequency electric power in a first sub-period of alternating first and second sub-periods is higher than a power level of the high-frequency electric power in the second sub-period. The matching method also includes a step of supplying a power wave of the other of the modulated wave and the continuous wave of the high-frequency electric power to the electrode in a later period of the two consecutive periods. The matching method also includes a step of stepwise changing the load impedance to a target impedance for the later period in the period in which the continuous wave is supplied of the two consecutive periods.

[0038] In one example embodiment, in the step of stepwise changing the load impedance, the load impedance can be stepwise changed so that an absolute value of a reflection coefficient of the high-frequency electric power stepwise changes to a set target value for the later period.

[0039] In one example embodiment, after the electric power to be supplied to the electrode is switched from the modulated wave to the continuous wave, the load impedance can be stepwise changed so that the absolute value of the reflection coefficient of the high-frequency electric power stepwise decreases to zero.

[0040] In one example embodiment, before the electric power to be supplied to the electrode is switched from the continuous wave to the modulated wave, the load impedance can be stepwise changed so that the absolute value of the reflection coefficient of the high-frequency electric power stepwise increases to a set target value greater than zero. The set target value can be 0.3 or more and 0.5 or less.

[0041] In one example embodiment, the load impedance can also be changed stepwise over a plurality of sub-periods during the period in which the continuous wave is supplied, so that the absolute value of the reflection coefficient changes stepwise to a set target value for the subsequent period. The length of each of the plurality of sub-periods is set to 0.5 seconds or more, and the difference between the target value of the absolute value of the reflection coefficient in one of any two consecutive sub-periods included in the plurality of sub-periods and the target value of the absolute value of the reflection coefficient in the other sub-period is set to 0.2 or less. Alternatively, the length is set to 0.2 seconds or more, and the difference is set to 0.1 or less. The length can also be set to 0.5 seconds or more, and the difference can be set to 0.05 or less.

[0042] Various embodiments will be described in detail below with reference to the attached drawings. In the drawings, like or corresponding elements are denoted by like reference numerals.

[0043] Figure 1 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to one example embodiment. Figure 1 The plasma processing apparatus 1 shown is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 has a chamber 10. The chamber 10 has an internal space provided therein.

[0044] The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space of the chamber 10 is provided at the inner side of the chamber body 12. The chamber body 12 is formed of a material such as aluminum. A film having plasma resistance is formed on the inner wall surface of the chamber body 12. The film can be a film formed by an anodization treatment or a ceramic film such as a film formed of yttrium oxide. The chamber body 12 is grounded. An opening 12p is formed in the side wall of the chamber body 12. The substrate W is transported between the internal space of the chamber 10 and the outside of the chamber 10 through the opening 12p. The opening 12p is openable and closable by a gate valve 12g. The gate valve 12g is disposed along the side wall of the chamber body 12.

[0045] An insulating plate 13 is provided on the bottom of the chamber body 12. The insulating plate 13 is formed of, for example, ceramic. A support table 14 is provided on the insulating plate 13. The support table 14 has a substantially disc shape. The support table 14 supports a susceptor 16 disposed thereon. The susceptor 16 is disposed in the chamber 10. The susceptor 16 is formed of an electrically conductive material such as aluminum. The susceptor 16 constitutes a lower electrode.

[0046] The pedestal 16 supports an electrostatic chuck 18 provided thereon. The electrostatic chuck 18 is provided in the chamber 10. The electrostatic chuck 18 is capable of holding a substrate W placed thereon. The electrostatic chuck 18 has a main body and an electrode 20. The main body of the electrostatic chuck 18 is formed of a dielectric and has a substantially disc shape. The electrode 20 is a conductive film provided in the main body of the electrostatic chuck 18. The electrode 20 is electrically connected to a direct current power source 24 via a switch 22. When a direct current voltage from the direct current power source 24 is applied to the electrode 20, electrostatic attraction is generated between the substrate W and the electrostatic chuck 18. With the generated electrostatic attraction, the substrate W is attracted to the electrostatic chuck 18 and held thereby.

[0047] The pedestal 16 and the electrostatic chuck 18 constitute a substrate support. The substrate support supports a peripheral ring 26 mounted thereon. The peripheral ring 26 is disposed so as to surround the periphery of the substrate W. That is, the substrate W is disposed in an area surrounded by the peripheral ring 26 and on the electrostatic chuck 18. The outer peripheral surfaces of the pedestal 16 and the support table 14 are each covered with a cylindrical inner wall member 28. The inner wall member 28 is formed of, for example, quartz.

[0048] A flow path 14f is formed in the inside of the support table 14. The flow path 14f extends, for example, spirally with respect to a central axis extending in the vertical direction. The flow path 14f is supplied with a heat exchange medium cw (e.g., a refrigerant such as cooling water) from a supply device (e.g., a cooling unit) provided outside the chamber 10 via a pipe 32a. The heat exchange medium supplied to the flow path 14f is recovered to the supply device via a pipe 32b. By adjusting the temperature of the heat exchange medium with the supply device, the temperature of the substrate W can be adjusted. Also, the plasma processing apparatus 1 is provided with a gas supply line 34. The gas supply line 34 is provided in order to supply a heat transfer gas (e.g., He gas) to a gap between the upper surface of the electrostatic chuck 18 and the back surface of the substrate W.

[0049] The plasma processing apparatus 1 can have one or more high frequency power sources. In an embodiment, the plasma processing apparatus 1 has a first high frequency power source (i.e., a high frequency power source 36) and a second high frequency power source (i.e., a high frequency power source 38). The high frequency power source 36 is connected to the pedestal 16 (i.e., a lower electrode) via a conductor 44 (e.g., a power supply rod) and a first matcher (i.e., a matcher 40). The high frequency power source 38 is connected to the pedestal 16 (i.e., a lower electrode) via the conductor 44 and a second matcher (i.e., a matcher 42). Further, the high frequency power source 36 can not be connected to the lower electrode but connected to an upper electrode described later via the matcher 40. The plasma processing apparatus 1 can not have one of the group of the high frequency power source 36 and the matcher 40 and the group of the high frequency power source 38 and the matcher 42.

[0050] The high-frequency power supply 36 is capable of generating a first high-frequency electric power (i.e., high-frequency electric power RF1) for plasma processing in the chamber 10. The high-frequency electric power RF1 is mainly used for generation of plasma. The fundamental frequency f B1 for example, 100 MHz. The high-frequency power supply 38 is capable of generating a second high-frequency electric power (i.e., high-frequency electric power RF2) for plasma processing in the chamber 10. The frequency of the high-frequency electric power RF2 is lower than the frequency of the high-frequency electric power RF1. The fundamental frequency f B2 for example, 13.56 MHz.

[0051] The matcher 40 has a circuit for setting the impedance of the load side (e.g., the lower electrode side) of the high-frequency power supply 36, i.e., the load impedance. The matcher 42 has a circuit for setting the impedance of the load side (the lower electrode side) of the high-frequency power supply 38, i.e., the load impedance. The matcher 40 and the matcher 42 can each be an electronically controlled matcher. Details of the matcher 40 and the matcher 42 are described later.

[0052] The matcher 40 and the conductor 44 constitute a part of a power supply line 43. The high-frequency electric power RF1 is supplied to the susceptor 16 via the power supply line 43. The matcher 42 and the conductor 44 constitute a part of a power supply line 45. The high-frequency electric power RF2 is supplied to the susceptor 16 via the power supply line 45.

[0053] The plasma processing apparatus 1 further has an upper electrode 46. The upper electrode 46 constitutes the top of the chamber 10. The upper electrode 46 is provided in a manner capable of closing the opening of the upper end of the chamber main body 12. The internal space of the chamber 10 contains a processing region PS. The processing region PS is the space between the upper electrode 46 and the susceptor 16. The plasma processing apparatus 1 generates plasma in the processing region PS using the high-frequency electric field generated between the upper electrode 46 and the susceptor 16. The upper electrode 46 is grounded. Further, in the case where the high-frequency power supply 36 is not connected to the lower electrode but is connected to the upper electrode 46 via the matcher 40, the upper electrode 46 is not grounded, and the upper electrode 46 is electrically separated from the chamber main body 12.

[0054] The upper electrode 46 has a top plate 48 and a support body 50. A plurality of gas ejection holes 48a are formed in the top plate 48. The top plate 48 is formed of, for example, a silicon-based material such as Si, SiC. The support body 50 is a member that supports the top plate 48 in a detachable manner, is formed of a conductor such as aluminum, and has a film having plasma resistance formed on the surface thereof.

[0055] In the inside of the support body 50, a gas buffer chamber 50b is formed. Further, in the support body 50, a plurality of gas holes 50a are formed. The plurality of gas holes 50a respectively extend from the gas buffer chamber 50b to communicate with the plurality of gas ejection holes 48a. The gas buffer chamber 50b is connected with a gas supply pipe 54. The gas supply pipe 54 is connected with a gas source 56 via a flow controller 58 (for example, a mass flow controller) and an on-off valve 60. The gas from the gas source 56 is supplied to the inside space of the chamber 10 via the flow controller 58, the on-off valve 60, the gas supply pipe 54, the gas buffer chamber 50b, and the plurality of gas ejection holes 48a. The flow rate of the gas supplied from the gas source 56 to the inside space of the chamber 10 is adjusted by the flow controller 58.

[0056] Below the space between the susceptor 16 and the side wall of the chamber body 12, an exhaust port 12e is provided at the bottom of the chamber body 12. The exhaust port 12e is connected with an exhaust pipe 64. The exhaust pipe 64 is connected with an exhaust device 66. The exhaust device 66 has a pressure regulator such as an automatic pressure control valve and a vacuum pump such as a turbo molecular pump. The exhaust device 66 depressurizes the inside space of the chamber 10 to a specified pressure.

[0057] The plasma processing device 1 further has a main control section 70. The main control section 70 includes one or more microcomputers. The main control section 70 can have a processor, a storage device such as a memory, an input device such as a keyboard, a display device, an input / output structure of a signal, and the like. The processor of the main control section 70 executes software (program) stored in the storage device, and controls the operation of each of the sections of the plasma processing device 1 and the operation (flow) of the entire device of the plasma processing device 1 according to recipe data. The main control section 70, for example, controls the high frequency power source 36, the high frequency power source 38, the matcher 40, the matcher 42, the flow controller 58, the on-off valve 60, the exhaust device 66, and the like.

[0058] In the case where the plasma processing is performed in the plasma processing device 1, first, the gate valve 12g is opened. Next, the wafer W is carried into the chamber 10 via the opening 12p, and is placed on the electrostatic chuck 18. Then, the gate valve 12g is closed. Next, the processing gas is supplied from the gas source 56 to the inside space of the chamber 10, and the exhaust device 66 is operated to set the pressure in the inside space of the chamber 10 to a specified pressure. Then, the high frequency electric power RF1 and / or the high frequency electric power RF2 is supplied to the susceptor 16. Also, the direct current voltage from the direct current power source 24 is applied to the electrode 20 of the electrostatic chuck 18, and the wafer W is held by the electrostatic chuck 18. Then, the processing gas is excited by the high frequency electric field formed between the susceptor 16 and the upper electrode 46. As a result, the plasma is generated in the processing region PS.

[0059] Hereinafter, the plasma processing device 1 will be described with reference to Figure 1 and the like.Figure 2 and Figure 3 . Figure 2 is a graph showing one example of a time chart of the first high-frequency electric power and the second high-frequency electric power. Figure 3 is a graph showing another example of a time chart of the first high-frequency electric power and the second high-frequency electric power. The plasma processing apparatus 1 can utilize at least one of the modulated wave MW1 of the high-frequency electric power RF1 or the modulated wave MW2 of the high-frequency electric power RF2 in the period P1 for plasma processing within the chamber 10. The modulated wave MW1 is generated by the high-frequency power source 36. The modulated wave MW2 is generated by the high-frequency power source 38. As Figure 2 and Figure 3 indicated by the dotted line in the period P1, the continuous wave CW1 of the high-frequency electric power RF1 or the continuous wave CW2 of the high-frequency electric power RF2 can also be utilized. The continuous wave CW1 is generated by the high-frequency power source 36. The continuous wave CW2 is generated by the high-frequency power source 38. The mode of utilizing the modulated wave MW1 and the modulated wave MW2 in the period P1 is a first mode. The mode of utilizing the modulated wave MW1 and the continuous wave CW2 in the period P1 is a second mode. The mode of utilizing the continuous wave CW1 and the modulated wave MW2 in the period P1 is a third mode.

[0060] The period P1 includes the first sub-period SP11 and the second sub-period SP12 alternately. The modulated wave MW1 is generated by the high-frequency power source 36 in such a manner that the power level of the high-frequency electric power RF1 in the first sub-period SP11 is higher than the power level of the high-frequency electric power RF1 in the second sub-period SP12. The power level of the high-frequency electric power RF1 in the second sub-period SP12 can also be 0 [W]. The modulated wave MW2 is generated by the high-frequency power source 38 in such a manner that the power level of the high-frequency electric power RF2 in the first sub-period SP11 is higher than the power level of the high-frequency electric power RF2 in the second sub-period SP12. The power level of the high-frequency electric power RF2 in the second sub-period SP12 can also be 0 [W].

[0061] The first sub-period SP11 and the second sub-period SP12 following it constitute one cycle CP. The ratio of the first sub-period SP11 in one cycle CP, i.e., the duty ratio can be an arbitrary value. For example, the duty ratio can be controlled to a value within a range of 10% or more and 90% or less. Further, the reciprocal of one cycle CP, i.e., the modulation frequency can be controlled to an arbitrary frequency. However, the modulation frequency is lower than the fundamental frequency f B1 and the fundamental frequency f B2 . The modulation frequency can be, for example, a frequency within a range of 0.1 kHz or more and 100 kHz or less.

[0062] In addition, the plasma processing apparatus 1 can continuously the continuous wave CW1 and the continuous wave CW2 in the period P2. That is, the high-frequency electric power RF1 and the high-frequency electric power RF2 are continuously supplied between the start time of the period P2 and the end time of the period P2. The length of the period P2 is longer than the length of one cycle CP.

[0063] The period P1 and the period P2 are two consecutive periods. As shown in Figure 2 , the period P1 of the two consecutive periods can be a preceding period PA, and the period P2 can be a succeeding period PB. Alternatively, as shown in Figure 3 , the period P2 of the two consecutive periods can be the preceding period PA, and the period P1 can be the succeeding period PB. The period P1 and the period P2 can be alternately repeated. That is, the high-frequency power source 36 supplies the power wave W11 in the preceding period PA. The power wave W11 is one of the modulation wave MW1 and the continuous wave CW1. The high-frequency power source 36 supplies the power wave W11 or the power wave W12 in the succeeding period PB. The power wave W12 is the other of the modulation wave MW1 and the continuous wave CW1. The high-frequency power source 38 supplies the power wave W21 in the preceding period PA. The power wave W21 is one of the modulation wave MW2 and the continuous wave CW2. The high-frequency power source 38 supplies the power wave W21 or the power wave W22 in the succeeding period PB. The power wave W22 is the other of the modulation wave MW2 and the continuous wave CW2. In the succeeding period PB, at least one of the power wave W12 or the power wave W22 is supplied.

[0064] Hereinafter, the high-frequency power source 36, the matching device 40, the high-frequency power source 38, and the matching device 42 will be described in detail with reference to Figures 4-7 . Figure 4 is a view showing one example of the structure of the first high-frequency power source and the first matching device of the plasma processing apparatus shown in Figure 1 Figure 5 is a view showing one example of the structure of the first matching device of the plasma processing apparatus shown in Figure 1 Figure 6 is a view showing one example of the structure of the second high-frequency power source and the second matching device of the plasma processing apparatus shown in Figure 1 Figure 7 is a view showing one example of the structure of the second matching device of the plasma processing apparatus shown in Figure 1

[0065] As shown in Figure 4 ​​​​As shown, in one embodiment, the high-frequency power source 36 has an oscillator 36a, a power amplifier 36b, a power sensor 36c, and a power source control section 36e. The power source control section 36e is constituted by a processor such as a CPU. The power source control section 36e applies control signals to the oscillator 36a, the power amplifier 36b, and the power sensor 36c, respectively, and controls the oscillator 36a, the power amplifier 36b, and the power sensor 36c. The power source control section 36e generates the control signals to be applied to the oscillator 36a, the power amplifier 36b, and the power sensor 36c, respectively, using a signal applied from the main control section 70 and a signal applied from the power sensor 36c.

[0066] The signal applied from the main control section 70 to the power source control section 36e contains a first frequency setting signal and a mode setting signal. The first frequency setting signal is a signal that specifies a set frequency of the high-frequency electric power RF1. The mode setting signal is a signal that specifies a selected mode among the first to third modes. In the case where the first mode or the second mode is specified, the signal applied from the main control section 70 to the power source control section 36e further contains a first modulation setting signal. The first modulation setting signal is a signal that specifies a modulation frequency and a duty ratio of the modulation wave MW1. Further, the first modulation setting signal is also a signal that specifies a power level of the modulation wave MW1 in the first sub-period SP11 and a power level of the modulation wave MW1 in the second sub-period SP12. In the case where the third mode is specified, the signal applied from the main control section 70 to the power source control section 36e further contains a first power level setting signal that specifies a power of the continuous wave CW1.

[0067] The power source control section 36e controls the oscillator 36a to output a high-frequency signal having a set frequency (for example, a fundamental frequency f B1 ) specified by the first frequency setting signal. The output of the oscillator 36a is connected to the input of the power amplifier 36b. The power amplifier 36b generates the high-frequency electric power RF1 by amplifying the high-frequency signal output from the oscillator 36a. The power amplifier 36b is controlled by the power source control section 36e.

[0068] In the case where the first mode or the second mode is specified, the power source control section 36e controls the power amplifier 36b to generate the modulation wave MW1 from the high-frequency signal according to the first modulation setting signal in the period P1. In the case where the first mode or the second mode is specified, the power source control section 36e controls the power amplifier 36b to generate the continuous wave CW1 from the high-frequency signal according to the first power level setting signal in the period P2. Further, in the case where the third mode is specified, the power source control section 36e controls the power amplifier 36b to generate the continuous wave CW1 from the high-frequency signal according to the first power level setting signal in the period P1 and in the period P2.

[0069] A power sensor 36c is provided at a stage subsequent to the power amplifier 36b. The power sensor 36c has a directional coupler, a forward wave detector, and a reflected wave detector. The directional coupler applies a portion of a forward wave of the high-frequency electric power RF1 to the forward wave detector, and applies a reflected wave to the reflected wave detector. A first frequency-determination signal that determines a set frequency of the high-frequency electric power RF1 is applied from the power source control section 36e to the power sensor 36c. The forward wave detector generates a measurement value of a power level of a component having the same frequency as the set frequency determined by the first frequency-determination signal among full frequency components of the forward wave, i.e., a measurement value P f11 of a power level of the forward wave. The measurement value P f11 is applied to the power source control section 36e.

[0070] The first frequency-determination signal is also applied from the power source control section 36e to the reflected wave detector. The reflected wave detector generates a measurement value of a power level of a component having the same frequency as the set frequency determined by the first frequency-determination signal among full frequency components of the reflected wave, i.e., a measurement value P r11 of a power level of the reflected wave. The measurement value P r11 is applied to the power source control section 36e. In addition, the reflected wave detector generates a measurement value of a total power level of the full frequency components of the reflected wave, i.e., a measurement value P r12 of a power level of the reflected wave. The measurement value P r12 is applied to the power source control section 36e for protecting the power amplifier 36b.

[0071] In one embodiment, the high-frequency power source 36 can also perform load power control in the period P1. That is, the high-frequency power source 36 can also adjust the power level of the high-frequency electric power RF1 so that the load power level of the high-frequency electric power RF1 in the period P1 approaches or coincides with the designated target power level. The power source control section 36e can control the power amplifier 36b in the load power control of the high-frequency power source 36.

[0072] In the load power control in the case where the first mode or the second mode is designated, the power source control section 36e can control the power amplifier 36b to adjust the power level of the modulated wave MW1 in the first sub-period SP11. The power level of the modulated wave MW1 in the first sub-period SP11 can be adjusted so that the load power level P L11 in the monitoring period MP1 approaches or coincides with the designated target power level.

[0073] The monitoring period MP1 is a period within the first sub-period SP11. The monitoring period MP1 can be a period that starts after a prescribed time length elapses from the start time of the first sub-period SP11. The monitoring period MP1 is designated by the main control section 70. The load power level P L11is the difference between the power level of the forward wave of the high-frequency electric power RF1 in the monitoring period MP1 and the power level of the reflected wave of the high-frequency electric power RF1 in the monitoring period MP1. The load power level P L11 is taken as the difference between the measured value P f11 and the measured value P r11 . The load power level P L11 may also be taken as the difference between the average value of the measured value P f11 and the average value of the measured value P r11 . Alternatively, the load power level P L11 may also be taken as the difference between the moving average value of the measured value P f11 and the moving average value of the measured value P r11 .

[0074] In the case where the power level of the modulated wave MW1 in the second sub-period SP12 is not 0 [W], the high-frequency power source 36 can also perform load power control of the modulated wave MW1 in the second sub-period SP12. In this load power control, the power source control section 36e can control the power amplifier 36b to adjust the power level of the modulated wave MW1 in the second sub-period SP12. The power level of the modulated wave MW1 in the second sub-period SP12 can be adjusted so that the load power level P L12 in the monitoring period MP2 approaches or coincides with the specified target power level.

[0075] The monitoring period MP2 can also be a period coinciding with the second sub-period SP12. Alternatively, the monitoring period MP2 can also be a period within the second sub-period SP12, which is a period starting after a prescribed time length has elapsed from the start time of the second sub-period SP12. The monitoring period MP2 is specified by the main control section 70. The load power level P L12 is the difference between the power level of the forward wave of the high-frequency electric power RF1 in the monitoring period MP2 and the power level of the reflected wave of the high-frequency electric power RF1 in the monitoring period MP2. The load power level P L12 is taken as the difference between the measured value P f11 and the measured value P r11 . The load power level P L12 may also be taken as the difference between the average value of the measured value P f11 and the average value of the measured value P r11 . Alternatively, the load power level P L12 may also be taken as the difference between the moving average value of the measured value P f11 and the moving average value of the measured value P r11 .

[0076] In the case where the third mode is designated, the high-frequency power source 36 can also perform load power control. In the load power control in the case where the third mode is designated, the power source control section 36e can control the power amplifier 36b to adjust the power level of the continuous wave CW1 in the period P1. The power level of the continuous wave CW1 in the period P1 can be adjusted so that the average value of the load power level P L11 in the monitoring period MP2 coincides with or is close to the designated target power level. L12

[0077] The matching section 40 can set the impedance on the load side of the high-frequency power source 36, i.e., the load impedance. The matching section 40 can also set the load impedance of the high-frequency power source 36 in the period P1 to a target impedance different from the output impedance of the high-frequency power source 36 in each of the first and second modes. The load impedance of the high-frequency power source 36 in the period P1 can also be determined from the measured value of the load impedance of the high-frequency power source 36 in the monitoring period MP1.

[0078] The matching section 40 can also match the load impedance of the high-frequency power source 36 in the period P1 to the output impedance of the high-frequency power source 36 in the third mode. Alternatively, the matching section 40 can also set the load impedance of the high-frequency power source 36 in the period P1 to a target impedance different from the output impedance of the high-frequency power source 36 in the third mode, as in the first and second modes.

[0079] The matching section 40 can stepwise change the load impedance of the high-frequency power source 36 in the period P2 to the target impedance for the subsequent period PB in each of the first and second modes. That is, the matching section 40 can stepwise change the load impedance of the high-frequency power source 36 in the period P2 before or after the switching of the electric power generated by the high-frequency power source 36 from the power wave W11 to the power wave W12 to the target impedance for the subsequent period PB.

[0080] The matching section 40 can stepwise change the load impedance of the high-frequency power source 36 in the period P2 to the target impedance for the subsequent period PB in each of the first and second modes, as shown in Figure 8 and Figure 9 The matching section 40 can stepwise change the load impedance of the high-frequency power source 36 in the period P2 to the target impedance for the subsequent period PB in each of the first and second modes, as shown in Figure 8 The matching section 40 can stepwise change the load impedance of the high-frequency power source 36 in the period P2 to the target impedance for the subsequent period PB in each of the first and second modes, as shown in Figure 9 The matching section 40 can stepwise change the load impedance of the high-frequency power source 36 in the period P2 to the target impedance for the subsequent period PB in each of the first and second modes, as shown in ​

[0081] Period P2 contains multiple consecutive sub-periods SP. These sub-periods SP include sub-periods SP1, SP2, ..., SP. N Matcher 40 is able to proceed through sub-periods SP1, SP2, ..., SP during period P2. N The load impedance of the high-frequency power supply 36 is changed in a stepped manner so that the absolute value of the reflection coefficient Γ1, “Γ1”, is changed in a stepped manner to the target value set for PB in the later period. Figure 8 As shown, when the subsequent period PB is period P2, the matcher 40, after the subsequent period PB (period P2) begins, proceeds through the sub-periods SP1, SP2, ..., SP within period P2. N The load impedance of the high-frequency power supply 36 is changed in stages. For example... Figure 9 As shown, when the later period PB is period P1, the matcher 40 proceeds through the sub-periods SP1, SP2, ..., SP2 within the period P2 before the start of the later period PB (period P1). N The load impedance of the high-frequency power supply 36 is changed in stages. During this period, P2 also includes the secondary period SP. (N+1) During the secondary period, SP (N+1) It is with the secondary period SP N Continuous period. Matching unit 40 sets the load impedance of high-frequency power supply 36 to match the secondary period SP. (N+1) The absolute value of the reflection coefficient Γ1, |Γ1|, is set as the target value for the subsequent period PB. Hereinafter, the sub-periods SP1, SP2, ..., SP... N SP (N+1) Each of the sub-periods is called a sub-period SP. i "i" is the index of an integer greater than or equal to 1 and less than N+1.

[0082] Matching unit 40 can also, in the third mode, match the load impedance of the high-frequency power supply 36 in period P2 with the output impedance of the high-frequency power supply 36. Similarly to the first and second modes, in the third mode, matching unit 40 can also, in the third mode, stepwise change the load impedance of the high-frequency power supply 36 in period P2 to the target impedance used in the later period PB.

[0083] In one embodiment, the matcher 40 is as follows: Figure 4 As shown, the device includes a matching circuit 40a, a sensor 40b, a controller 40c, an actuator 40d, and an actuator 40e. The matching circuit 40a may include a variable reactance element 40g and a variable reactance element 40h. Each of the variable reactance elements 40g and 40h is, for example, a variable capacitor. Furthermore, the matching circuit 40a may also include an inductor, etc.

[0084] The controller 40c operates under the control of the main control section 70. The controller 40c adjusts the load impedance of the high-frequency power source 36 in accordance with the measured value of the impedance on the load side of the high-frequency power source 36, i.e., the load impedance, applied from the sensor 40b. The controller 40c controls the actuators 40d and 40e to adjust the reactance of each of the variable reactance elements 40g and 40h, thereby adjusting the load impedance of the high-frequency power source 36. The actuators 40d and 40e are, for example, electric motors.

[0085] The sensor 40b is capable of acquiring the measured value of the load impedance of the high-frequency power source 36. In an embodiment, the measured value of the load impedance of the high-frequency power source 36 is acquired as a moving average. As shown in FIG. 6, the sensor 40b can also have a current detector 102A, a voltage detector 104A, filters 106A and 108A, average value operators 110A and 112A, a moving average operator 114A, and an impedance operator 118A. Figure 5

[0086] The voltage detector 104A detects the voltage waveform of the high-frequency electric power RF1 transmitted on the supply line 43, and outputs a voltage waveform analog signal representing the voltage waveform. The voltage waveform analog signal is input to the filter 106A. The filter 106A generates a voltage waveform digital signal by digitizing the input voltage waveform analog signal. The filter 106A receives the above-mentioned first frequency determination signal from the power source control section 36e, extracts only the frequency component corresponding to the frequency determined by the first frequency determination signal from the voltage waveform digital signal, thereby generating a filtered voltage waveform signal. The filter 106A can be constituted by an FPGA (Field Programmable Gate Array).

[0087] The filtered voltage waveform signal generated by the filter 106A is output to the average value operator 110A. The average value operator 110A receives a monitoring period setting signal from the main control section 70. The average value operator 110A calculates the average value of the voltage within the period determined by the monitoring period setting signal from the filtered voltage waveform signal. The average value operator 110A calculates the average value V A11 of the voltage in each monitoring period MP1 as the voltage average. In the case where the third mode is designated, the average value operator 110A can also calculate the average value V A12 of the voltage in each monitoring period MP2 as the voltage average. Further, the average value operator 110A can be constituted by, for example, an FPGA (Field Programmable Gate Array).

[0088] The moving average operator 114A calculates the average value V A11 of the voltage of the high-frequency electric power RF1 in the adjacent and prescribed number of monitoring periods MP1 from the plurality of average values V A11 ​moving average value V MA11 moving average value V MA11 is output to the impedance calculator 118A.

[0089] In the third mode, the moving average calculator 114A can further calculate a moving average value V A12 of the voltage of the high-frequency electric power RF1 in the adjacent and prescribed number of monitoring periods MP2 A12 moving average value V MA12 moving average value V MA12 is output to the impedance calculator 118A.

[0090] The current detector 102A detects a current waveform of the high-frequency electric power RF1 transmitted on the power supply line 43, and outputs a current waveform analog signal representing the current waveform. The current waveform analog signal is input to the filter 108A. The filter 108A generates a current waveform digital signal by digitizing the input current waveform analog signal. The filter 108A receives the above-described first frequency determination signal from the power source control section 36e, and extracts only a frequency component corresponding to the frequency determined by the first frequency determination signal from the current waveform digital signal, thereby generating a filtered current waveform signal. The filter 108A can be constituted by, for example, an FPGA (Field Programmable Gate Array).

[0091] The filtered current waveform signal generated by the filter 108A is output to the average calculator 112A. The average calculator 112A receives a monitoring period setting signal from the main control section 70. The average calculator 112A calculates an average value of the current in a period determined by the monitoring period setting signal from the filtered current waveform signal. The average calculator 112A calculates an average value I A11 of the current in the monitoring period MP1 in each period P1 as the average value of the current. In the case where the third mode is designated, the average calculator 112A can further calculate an average value I A12 of the current in each monitoring period MP2 as the average value of the current. Further, the average calculator 112A can be constituted by, for example, an FPGA (Field Programmable Gate Array).

[0092] The moving average calculator 116A calculates a moving average value I A11 of the current of the high-frequency electric power RF1 in the adjacent and prescribed number of monitoring periods MP1 A11 moving average value I MA11 moving average value I MA11 is output to the impedance calculator 118A.

[0093] In the third mode, the moving average calculator 116A can further calculate a moving average value IA12 the average value I of the current of the high-frequency electric power RF1 in the monitoring period MP2 according to the adjacent and prescribed number A12 the moving average value I MA12 . The moving average value I MA12 is output to the impedance calculator 118A.

[0094] The impedance calculator 118A calculates the moving average value Z of the load impedance of the high-frequency power source 36 according to the moving average value I MA11 and the moving average value V MA11 MA11 . The moving average value Z MA11 is a measured value of the load impedance of the high-frequency power source 36 in the monitoring period MP1. In the third mode, the impedance calculator 118A can also calculate the moving average value Z of the load impedance of the high-frequency power source 36 according to the moving average value I MA12 and the moving average value V MA12 MA12 . The moving average value Z MA12 is a measured value of the load impedance of the high-frequency power source 36 in the monitoring period MP2.

[0095] The controller 40c controls the matching circuit 40a to set the load impedance of the high-frequency power source 36. In one embodiment, the controller 40c adjusts the respective reactances of the variable reactance elements 40g and 40h by means of the actuator 40d and the actuator 40e, thereby setting the load impedance of the high-frequency power source 36.

[0096] The controller 40c adjusts the load impedance of the high-frequency power source 36 in the period PI determined by the moving average value Z MA11 to a target impedance different from the output impedance of the high-frequency power source 36 in each of the first and second modes.

[0097] In one embodiment, the controller 40c can determine the target impedance according to a set target value of the absolute value |Γ1| of the reflection coefficient Γ1 of the high-frequency electric power RF1 in the period PI. The set target value of the absolute value |Γ1| in the period PI can be a value larger than 0. For example, the set target value of the absolute value |Γ1| in the period PI is 0.3 or more and 0.5 or less. The reflection coefficient Γ1 is defined by the following (1) formula.

[0098] Γ1 = (Z1 - Z 01 ) / (Z1 + Z 01 )... (1)

[0099] In the (1) formula, Z 01 ​​is a characteristic impedance of the power supply line 43, and is generally 50 Ω. In equation (1), Z1 is a target impedance. The controller 40c determines the target impedance Z1 corresponding to the set target value of the absolute value |Γ1| in the period P1, based on equation (1). The controller 40c sets the load impedance of the high-frequency power source 36 so that the load impedance of the high-frequency power source 36 determined by the moving average value Z MA11 The load impedance of the high-frequency power source 36 in the period P1 is determined so as to be close to or identical to the target impedance Z1.

[0100] In the case where the third mode is designated, the controller 40c can also match the load impedance of the high-frequency power source 36 to the output impedance (matching point) of the high-frequency power source 36 in the period P1. The load impedance of the high-frequency power source 36 can be determined by the average of the moving average value Z MA11 and the moving average value Z MA12 Alternatively, the controller 40c can also adjust the load impedance of the high-frequency power source 36 in the period P1 to a target impedance different from the output impedance of the high-frequency power source 36 in the third mode, as in the first and second modes.

[0101] As described above, the matching device 40 can stepwise change the load impedance of the high-frequency power source 36 in each of the first and second modes so that the absolute value |Γ1| of the reflection coefficient Γ1 stepwise changes to the set target value for the subsequent period PB. As described above, the matching device 40 stepwise changes the load impedance of the high-frequency power source 36 via a plurality of sub-periods SP within the period P2. The time length of each of the plurality of sub-periods SP (i.e., SP1, SP2,..., SP N ) is TL.

[0102] The target values of the absolute value |Γ1| of the reflection coefficient Γ1 of the high-frequency electric power RF1 in the plurality of sub-periods SP1, SP2,..., SP N are different from each other. The difference between the target value of the absolute value |Γ1| of the reflection coefficient Γ1 in one of any two consecutive sub-periods included in the plurality of sub-periods SP2 and the target value of the absolute value |Γ1| of the reflection coefficient Γ1 in the other period is ΔΓ1. Further, in Figure 8 and Figure 9 , ΔΓ1 is denoted as ΔΓ. As Figure 8 indicated, the target value of the absolute value |Γ1| of the reflection coefficient Γ1 in the sub-period SP (N+1) , i.e., the set target value, is zero in the case where the subsequent period PB is the period P2. As Figure 9 indicated, the target value of the absolute value |Γ1| of the reflection coefficient Γ1 in the sub-period SP (N+1)The target value of the absolute value |Γ1| of the reflection coefficient Γ1 is set to be greater than zero, for example, 0.3 or more and 0.5 or less. In one embodiment, TL can be set to 0.5 seconds or more and ΔΓ1 can be set to 0.2 or less. Alternatively, TL can be set to 0.2 seconds or more and ΔΓ1 can be set to 0.1 or less. Alternatively, TL can be set to 0.5 seconds or more and ΔΓ1 can be set to 0.05 or less.

[0103] Controller 40c sets the load impedance of the high-frequency power supply 36. Specifically, controller 40c during the secondary period SP i In the middle, the load impedance of the high-frequency power supply 36 is changed from the secondary period SP. i The target value of the absolute value |Γ1| of the reflection coefficient Γ1 of the high-frequency power RF1 is adjusted to the target impedance Z1 determined based on equation (1). Furthermore, the controller 40c can determine the sub-period SP based on the measured value of the load impedance of the high-frequency power supply 36 obtained in the sensor 40b. i The load impedance of the high-frequency power supply 36 is measured. The sensor 40b can determine the measured value of the load impedance of the high-frequency power supply 36 based on the aforementioned filtered voltage waveform signal and filtered current waveform signal.

[0104] When the third mode is specified, the controller 40c can also match the load impedance of the high-frequency power supply 36 to the output impedance (matching point) of the high-frequency power supply 36 during period P2. Similarly to the first and second modes, the controller 40c can also, in the third mode, during period P2, stepwise change the load impedance of the high-frequency power supply 36 to the target impedance for the subsequent period PB.

[0105] like Figure 6 As shown, in one embodiment, the high-frequency power supply 38 includes an oscillator 38a, a power amplifier 38b, a power sensor 38c, and a power control unit 38e. The power control unit 38e is a processor such as a CPU. The power control unit 38e applies control signals to the oscillator 38a, the power amplifier 38b, and the power sensor 38c respectively, thereby controlling the oscillator 38a, the power amplifier 38b, and the power sensor 38c. The power control unit 38e generates control signals to be applied to the oscillator 38a, the power amplifier 38b, and the power sensor 38c respectively using signals applied from the main control unit 70 and signals applied from the power sensor 38c.

[0106] The signal applied from the main control section 70 to the power control section 38e contains the second frequency setting signal and the above-mentioned mode setting signal. The second frequency setting signal is a signal that specifies the set frequency of the high-frequency electric power RF2. In the case where the first mode or the third mode is specified, the signal applied from the main control section 70 to the power control section 38e further contains the second modulation setting signal. The second modulation setting signal is a signal that specifies the modulation frequency and the duty ratio of the modulation wave MW2. Further, the second modulation setting signal is also a signal that specifies the power level of the modulation wave MW2 in the first sub-period SP11 and the power level of the modulation wave MW2 in the second sub-period SP12. Further, in the first mode, the modulation frequency of the modulation wave MW1 and the modulation frequency of the modulation wave MW2 can be the same as each other. In the case where the second mode is specified, the signal applied from the main control section 70 to the power control section 38e further contains the second power level setting signal that specifies the power of the continuous wave CW2.

[0107] The power control section 38e controls the oscillator 38a to output a high-frequency signal having a set frequency (for example, a fundamental frequency f B2 ) specified by the second frequency setting signal. The output of the oscillator 38a is connected to the input of the power amplifier 38b. The power amplifier 38b generates the high-frequency electric power RF2 by amplifying the high-frequency signal output from the oscillator 38a. The power amplifier 38b is controlled by the power control section 38e.

[0108] In the case where the first mode or the third mode is specified, the power control section 38e controls the power amplifier 38b to generate the modulation wave MW2 from the high-frequency signal in the period P1 in accordance with the second modulation setting signal. In the case where the first mode or the third mode is specified, the power control section 38e controls the power amplifier 38b to generate the continuous wave CW2 from the high-frequency signal in the period P2 in accordance with the second power level setting signal. Further, in the case where the second mode is specified, the power control section 38e controls the power amplifier 38b to generate the continuous wave CW2 from the high-frequency signal in the period P1 and in the period P2 in accordance with the second power level setting signal.

[0109] A power sensor 38c is provided at the rear stage of the power amplifier 38b. The power sensor 38c has a directional coupler, a forward wave detector, and a reflected wave detector. The directional coupler applies a part of the forward wave of the high-frequency electric power RF2 to the forward wave detector and applies the reflected wave to the reflected wave detector. A second frequency determination signal that determines the set frequency of the high-frequency electric power RF2 is applied from the power control section 38e to the power sensor 38c. The forward wave detector generates a measured value of the power level of the component having the same frequency as the set frequency determined by the second frequency determination signal among the full frequency components of the forward wave, that is, a measured value P f21 of the power level of the forward wave. The measured value P f21is applied to the power control section 38e.

[0110] The second frequency-determination signal is also applied to the reflected-wave detector from the power control section 38e. The reflected-wave detector generates a measurement value of a power level of a component in the full frequency component of the reflected wave that has the same frequency as the set frequency determined by the second frequency-determination signal, i.e., a measurement value P r21 of the power level of the reflected wave. The measurement value P r21 is applied to the power control section 38e. In addition, the reflected-wave detector generates a measurement value of the total power level of the full frequency component of the reflected wave, i.e., a measurement value P r22 of the power level of the reflected wave. The measurement value P r22 is applied to the power control section 38e.

[0111] In one embodiment, the high-frequency power source 38 can also perform load power control in the period P1. That is, the high-frequency power source 38 can adjust the power level of the high-frequency electric power RF2 so that the load power level of the high-frequency electric power RF2 in the period P1 approaches or coincides with the designated target power level. In the load power control in the high-frequency power source 38, the power control section 38e can control the power amplifier 38b.

[0112] In the load power control in the case where the first mode or the third mode is designated, the power control section 38e can control the power amplifier 38b to adjust the power level of the modulated wave MW2 in the first sub-period SP11. The power level of the modulated wave MW2 in the first sub-period SP11 can be adjusted so that the load power level P L21 in the monitoring period MP1 approaches or coincides with the designated target power level.

[0113] As described above, the monitoring period MP1 is a period within the first sub-period SP11. The monitoring period MP1 can be a period that starts after a prescribed length of time has elapsed from the start time of the first sub-period SP11. The monitoring period MP1 is designated by the main control section 70. The load power level P L21 is the difference between the power level of the traveling wave of the high-frequency electric power RF2 in the monitoring period MP1 and the power level of the reflected wave of the high-frequency electric power RF2 in the monitoring period MP1. The load power level P L21 is obtained as the difference between the measurement value P f21 and the measurement value P r21 . The load power level P L21 may also be obtained as the difference between the average of the measurement value P f21 in the monitoring period MP1 and the average of the measurement value P r21 . Alternatively, the load power level P L21 may also be obtained as the difference between the measurement value P f21The moving average and the measured value P r21 It is obtained by the difference of the moving averages.

[0114] Even when the power level of the modulated wave MW2 in the second sub-period SP12 is 0 [W], the high-frequency power supply 38 can still perform load power control of the modulated wave MW2 in the second sub-period SP12. In this load power control, the power supply control unit 38e can control the power amplifier 38b to adjust the power level of the modulated wave MW2 in the second sub-period SP12. The power level of the modulated wave MW2 in the second sub-period SP12 can be adjusted so that the load power level P in the monitoring period MP2 is... L22 It is close to or consistent with the specified target power level.

[0115] As described above, the monitoring period MP2 can also be the same as the second auxiliary period SP12. Alternatively, the monitoring period MP2 can also be a period within the second auxiliary period SP12, starting after a predetermined duration has elapsed from the start time of the second auxiliary period SP12. The monitoring period MP2 is specified by the main control unit 70. Load power level P L22 It is the difference between the power level of the traveling wave of the high-frequency electrical power RF2 in MP2 during the monitoring period and the power level of the reflected wave of the high-frequency electrical power RF2 in MP2 during the monitoring period. Load power level P L22 The measured value P in MP2 during the monitoring period f21 With the measured value P r21 The difference is used to determine the load power level P. L22 It can also be used as the measurement value P in MP2 during monitoring. f21 The average value and the measured value P r21 The difference is used to determine the value. Alternatively, the load power level P L22 It can also be used as the measurement value P in MP2 during multiple monitoring periods. f21 The moving average and the measured value P r21 It is obtained by the difference of the moving averages.

[0116] When the second mode is specified, the high-frequency power supply 38 can also perform load power control. Under load power control in the second mode, the power supply control unit 38e can control the power amplifier 38b to adjust the power level of the continuous wave CW2 during period P1. The power level of the continuous wave CW2 during period P1 can be adjusted to monitor the load power level P during period MP1. L21 During monitoring, the load power level P in MP2 L22 The average value is consistent with or close to the specified target power level.

[0117] The matcher 42 can set the impedance on the load side of the high-frequency power source 38, that is, the load impedance. The matcher 42 can also set the load impedance of the high-frequency power source 38 during the period P1 to a target impedance different from the output impedance of the high-frequency power source 38 in each of the first and third modes. The load impedance of the high-frequency power source 38 during the period P1 can also be determined from a measured value of the load impedance of the high-frequency power source 38 during the monitoring period MP1.

[0118] The matcher 42 can also match the load impedance of the high-frequency power source 38 during the period P1 to the output impedance of the high-frequency power source 38 in the second mode. Alternatively, the matcher 42 can also set the load impedance of the high-frequency power source 38 during the period P1 to a target impedance different from the output impedance of the high-frequency power source 38 in the second mode as in the first and third modes.

[0119] The matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 in each of the first and third modes. That is, the matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 before or after the switching of the electric power generated by the high-frequency power source 38 from the power wave W21 to the power wave W22.

[0120] The matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 in each of the first and third modes as shown in Figure 8 and Figure 9 The matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 in each of the first and third modes as shown in Figure 8 Figure 9 The matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 in each of the first and third modes as shown in

[0121] As described above, the subsequent period PB includes a plurality of sub-periods SP. As described above, the plurality of sub-periods SP include sub-periods SP1, SP2,..., SP N The matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 as the sub-periods SP1, SP2,..., SP N The matcher 42 can stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 as the sub-periods SP1, SP2,..., SP Figure 8 ​As shown, when the later period PB is period P2, the matcher 42, after starting the later period PB (period P2), proceeds through the sub-periods SP1, SP2, ..., SP within period P2. N The load impedance of the high-frequency power supply 38 is changed in stages. For example... Figure 9 As shown, when the later period PB is period P1, the matcher 42 proceeds through the sub-periods SP1, SP2, ..., SP2 within the period P2 before the start of the later period PB (period P1). N The load impedance of the high-frequency power supply 38 is changed in stages. The matching unit 42 sets the load impedance of the high-frequency power supply 38 to adjust the load impedance during the secondary period SP. (N+1) The absolute value of the reflection coefficient Γ2, |Γ2|, is set as the target value for setting PB in the later period.

[0122] Matching unit 42 can also, in the second mode, match the load impedance of the high-frequency power supply 38 during period P2 with the output impedance of the high-frequency power supply 38. Alternatively, similar to the first and third modes, in the second mode, matching unit 42 can stepwise change the load impedance of the high-frequency power supply 38 during period P2 to the target impedance used in the later period PB.

[0123] In one embodiment, the matcher 42 is as follows Figure 6 The device shown includes a matching circuit 42a, a sensor 42b, a controller 42c, an actuator 42d, and an actuator 42e. The matching circuit 42a may include a variable reactance element 42g and a variable reactance element 42h. Each of the variable reactance elements 42g and 42h is, for example, a variable capacitor. Furthermore, the matching circuit 42a may also include an inductor, etc.

[0124] The controller 42c operates under the control of the main control unit 70. The controller 42c adjusts the load impedance of the high-frequency power supply 38 based on the measured value of the impedance (i.e., load impedance) applied from the sensor 42b to the load side of the high-frequency power supply 38. The controller 42c controls actuators 42d and 42e to adjust the reactance of the variable reactance elements 42g and 42h, thereby adjusting the load impedance of the high-frequency power supply 38. Actuators 42d and 42e are, for example, electric motors.

[0125] Sensor 42b is capable of acquiring a measured value of the load impedance of the high-frequency power supply 38. In one embodiment, a moving average value is acquired as the measured value of the load impedance of the high-frequency power supply 38. Figure 7 As shown, sensor 42b may also include current detector 102B, voltage detector 104B, filters 106B and 108B, averaging processors 110B and 112B, moving average processors 114B and 116B, and impedance processor 118B.

[0126] The voltage detector 104B detects a voltage waveform of the high-frequency electric power RF2 transmitted on the power supply line 45, and outputs a voltage waveform analog signal representing the voltage waveform. The voltage waveform analog signal is input to the filter 106B. The filter 106B generates a voltage waveform digital signal by digitizing the input voltage waveform analog signal. The filter 106B receives the second frequency determination signal described above from the power source control section 38e, extracts only a frequency component corresponding to the frequency determined by the second frequency determination signal from the voltage waveform digital signal, and thereby generates a filtered voltage waveform signal. The filter 106B can be constituted by an FPGA (Field Programmable Gate Array).

[0127] The filtered voltage waveform signal generated by the filter 106B is output to the average value calculator 110B. The average value calculator 110B receives a monitoring period setting signal from the main control section 70. The average value calculator 110B calculates an average value of the voltage in a period determined by the monitoring period setting signal from the filtered voltage waveform signal. The average value calculator 110B calculates an average value V B11 of the voltage in the monitoring period MP1 as the average value of the voltage. In the case where the second mode is designated, the average value calculator 110B can also calculate an average value V B12 of the voltage in the monitoring period MP2 as the average value of the voltage. Further, the average value calculator 110B can be constituted by an FPGA (Field Programmable Gate Array), for example.

[0128] The moving average calculator 114B calculates a moving average V B11 of the average values V B11 of the voltage of the high-frequency electric power RF2 in the adjacent and prescribed number of monitoring periods MP1 from among the plurality of average values V MB11 that have been obtained. The moving average V MB11 is output to the impedance calculator 118B.

[0129] In the second mode, the moving average calculator 114B can also calculate a moving average V B12 of the average values V B12 of the voltage of the high-frequency electric power RF2 in the adjacent and prescribed number of monitoring periods MP2 from among the plurality of average values V MB12 that have been obtained. The moving average V MB12 is output to the impedance calculator 118B.

[0130] The current detector 102B detects a current waveform of the high-frequency electric power RF2 transmitted on the power supply line 45, and outputs a current waveform analog signal representing the current waveform. The current waveform analog signal is output to the filter 108B. The filter 108B generates a current waveform digital signal by digitizing the input current waveform analog signal. The filter 108B receives the above-mentioned second frequency determination signal from the power source control section 38e, extracts only a frequency component corresponding to the frequency determined by the second frequency determination signal from the current waveform digital signal, and thereby generates a filtered current waveform signal. The filter 108B can be constituted by, for example, an FPGA (Field Programmable Gate Array).

[0131] The filtered current waveform signal generated by the filter 108B is output to the average value calculator 112B. The average value calculator 112B receives a monitoring period setting signal from the main control section 70. The average value calculator 112B calculates an average value of the current in a period determined by the monitoring period setting signal from the filtered current waveform signal. The average value calculator 112B calculates an average value I B11 of the current in the monitoring period MP1 in each period PI as the average value of the current. In the case where the second mode is designated, the average value calculator 112B can also calculate an average value I B12 of the current in each monitoring period MP2 as the average value of the current. Further, the average value calculator 112B can be constituted by, for example, an FPGA (Field Programmable Gate Array).

[0132] The moving average calculator 116B calculates a moving average I B11 of the average values I B11 of the current of the high-frequency electric power RF2 in the adjacent and prescribed number of monitoring periods MP1 from the obtained plurality of average values I MB11 . The moving average I MB11 is output to the impedance calculator 118B.

[0133] In the second mode, the moving average calculator 116B can also calculate a moving average I B12 of the average values I B12 of the current of the high-frequency electric power RF2 in the adjacent and prescribed number of monitoring periods MP2 from the obtained plurality of average values I MB12 . The moving average I MB12 is output to the impedance calculator 118B.

[0134] The impedance calculator 118B calculates a moving average Z MB11 of the load impedance of the high-frequency power source 38 from the moving average I MB11 and the moving average V MB11 . The moving average Z MB11is a measured value of the load impedance of the high-frequency power source 38 in the monitoring period MP1. In the second mode, the impedance calculator 118B can also calculate the moving average value I MB12 and the moving average value V MB12 of the load impedance of the high-frequency power source 38. MB12 The moving average value Z MB12 is a measured value of the load impedance of the high-frequency power source 38 in the monitoring period MP2.

[0135] The controller 42c controls the matching circuit 42a to set the load impedance of the high-frequency power source 38. In one embodiment, the controller 42c adjusts the respective reactances of the variable reactance elements 42g and 42h by means of the actuators 42d and 42e, thereby setting the load impedance of the high-frequency power source 38.

[0136] The controller 42c adjusts the load impedance of the high-frequency power source 38 in the period PI determined by the moving average value Z MB11 to a target impedance different from the output impedance of the high-frequency power source 38 in each of the first and third modes.

[0137] In one embodiment, the controller 42c can determine the target impedance in accordance with a set target value of the absolute value |Γ2| of the reflection coefficient Γ2 of the high-frequency power RF2 in the period PI. The set target value of the absolute value |Γ2| in the period PI can be a value larger than 0. For example, the set target value of the absolute value |Γ2| in the period PI is 0.3 or more and 0.5 or less. The reflection coefficient Γ2 is defined by the following (2) formula.

[0138] Γ2 = (Z2 - Z 02 ) / (Z2 + Z 02 )... (2)

[0139] In the (2) formula, Z 02 is the characteristic impedance of the supply line 45, which is generally 50 Ω. In the (2) formula, Z2 is the target impedance. The controller 42c determines the target impedance Z2 corresponding to the set target value of the absolute value |Γ2| in the period PI on the basis of the (2) formula. The controller 42c sets the load impedance of the high-frequency power source 38 so that the load impedance of the high-frequency power source 38 in the period PI determined by the moving average value Z MB11 is close to or identical to the target impedance Z2.

[0140] In the case where the second mode is specified, the controller 42c can also match the load impedance of the high-frequency power source 38 to the output impedance (matching point) of the high-frequency power source 38 in the period PI. The load impedance of the high-frequency power source 38 can be determined by the moving average value Z MB11 and the moving average value Z MB12The average value is determined. Alternatively, similar to the first and third modes, in the second mode, the controller 42c also adjusts the load impedance of the high-frequency power supply 38 in P1 to a target impedance that is different from the output impedance of the high-frequency power supply 38.

[0141] As described above, in each of the first and third modes, the matching unit 42 is capable of stepwise changing the load impedance of the high-frequency power supply 38 so that the absolute value of the reflection coefficient Γ2, |Γ2|, changes stepwise to the set target value for the subsequent period PB. As described above, the matching unit 42 stepwise changes the load impedance of the high-frequency power supply 38 as multiple sub-periods SP pass through period P2.

[0142] Multiple sub-periods SP1, SP2, ..., SP N The target values ​​of the absolute value |Γ2| of the reflection coefficient Γ2 of the high-frequency electrical power RF2 in the multiple sub-periods SP2 are different from each other. The difference between the target value of the absolute value |Γ2| of the reflection coefficient Γ2 in one of the two consecutive sub-periods contained in SP2 and the target value of the absolute value |Γ2| of the reflection coefficient Γ2 in the other sub-period is ΔΓ2. Furthermore, in Figure 8 and Figure 9 In this context, ΔΓ2 is represented as ΔΓ. For example... Figure 8 As shown, when the subsequent period PB is period P2, the secondary period SP (N+1) The target value of the absolute value of the reflection coefficient Γ2, |Γ2|, is set to zero. For example... Figure 9 As shown, when the subsequent period PB is period P1, the secondary period SP (N+1) The target value of the absolute value of the reflection coefficient Γ2, |Γ2|, is set to be greater than zero, for example, 0.3 or more and 0.5 or less. In one embodiment, TL can be set to 0.5 seconds or more and ΔΓ2 can be set to 0.2 or less. Alternatively, TL can be set to 0.2 seconds or more and ΔΓ2 can be set to 0.1 or less. Or, TL can be set to 0.5 seconds or more and ΔΓ2 can be set to 0.05 or less.

[0143] Controller 42c sets the load impedance of the high-frequency power supply 38. Specifically, controller 42c during the secondary period SP i In the process, the load impedance of the high-frequency power supply 38 is adjusted to the target impedance Z2, which is based on the secondary period SP. i The target value of the absolute value |Γ2| of the reflection coefficient Γ2 of the high-frequency power RF2 is determined based on equation (2). Furthermore, the controller 42c can determine the sub-period SP based on the measured value of the load impedance of the high-frequency power supply 38 obtained from the sensor 42b. iThe sensor 42b is able to calculate a measured value of the load impedance of the high-frequency power source 38 from the filtered voltage waveform signal and the filtered current waveform signal described above.

[0144] In the case where the second mode is designated, the controller 42c can also match the load impedance of the high-frequency power source 38 to the output impedance (matching point) of the high-frequency power source 38 in the period P2. As in the first and third modes, the controller 42c can also stepwise change the load impedance of the high-frequency power source 38 to the target impedance for the subsequent period PB in the period P2 in the second mode.

[0145] In the plasma processing apparatus 1, the matcher 40 stepwise changes the load impedance to the target impedance for the subsequent period in the period in which the continuous wave CW1 is supplied before or after the electric power supplied from the high-frequency power source 36 is switched from the power wave W11 to the power wave W12. Therefore, the matcher 40 is able to track the change in the load impedance to be set after the electric power from the high-frequency power source 36 is switched from the power wave W11 to the power wave W12. Therefore, it is possible to reduce the reflection after the electric power supplied from the high-frequency power source 36 is switched from the power wave W11 to the power wave W12. Further, the matcher 42 stepwise changes the load impedance to the target impedance for the subsequent period in the period in which the continuous wave CW2 is supplied before or after the electric power supplied from the high-frequency power source 38 is switched from the power wave W21 to the power wave W22. Therefore, the matcher 42 is able to track the change in the load impedance to be set after the electric power from the high-frequency power source 38 is switched from the power wave W21 to the power wave W22. Therefore, it is possible to reduce the reflection after the electric power supplied from the high-frequency power source 38 is switched from the power wave W21 to the power wave W22.

[0146] In one embodiment, the matcher 40 adjusts the load impedance of the high-frequency power source 36 in the period PI to a target impedance different from the output impedance of the high-frequency power source 36. In accordance with this embodiment, it is possible to reduce the reflection from the load to the modulation wave MW1 in the period PI. In one embodiment, the matcher 42 adjusts the load impedance of the high-frequency power source 38 in the period PI to a target impedance different from the output impedance of the high-frequency power source 38 in each of the first and third modes. In accordance with this embodiment, it is possible to reduce the reflection from the load to the modulation wave MW2 in the period PI.

[0147] In one embodiment, load power control of the modulated wave MW1 can be performed during period P1. According to this embodiment, even if reflection occurs during period P1 due to the difference between the target impedance and the output impedance of the high-frequency power supply 36, the modulated wave MW1 of the target power level can still be coupled to the plasma. In one embodiment, load power control of the modulated wave MW2 can be performed during period P1. According to this embodiment, even if reflection occurs during period P1 due to the difference between the target impedance and the output impedance of the high-frequency power supply 38, the modulated wave MW2 of the target power level can still be coupled to the plasma.

[0148] The following is for reference Figure 10 . Figure 10 This is a flowchart illustrating a matching method in an exemplary implementation. Figure 10 In the matching method (hereinafter referred to as "Method MT"), the electrical power supplied by at least one of the high-frequency power supply 36 and high-frequency power supply 38 is switched from the power wave of one of the continuous wave and the modulated wave to the power wave of the other. That is, in Method MT, power wave W11 is supplied by high-frequency power supply 36, and power wave W21 is supplied by high-frequency power supply 38. Then, at least one of power wave W12 from high-frequency power supply 36 or power wave W22 from high-frequency power supply 38 is supplied. Power wave W11 can be supplied by high-frequency power supply 36 in two consecutive periods, or power wave W21 can be supplied by high-frequency power supply 36 in two consecutive periods. In Method MT, the electrical power supplied by at least one of the high-frequency power supply 36 and high-frequency power supply 38 is alternately switched from the power wave of one of the continuous wave and the modulated wave to the power wave of the other.

[0149] Method MT begins at step ST1. In step ST1, a power wave W11 is supplied by high-frequency power supply 36, and a power wave W21 is supplied by high-frequency power supply 38. During the execution of step ST1, the load impedance of high-frequency power supply 36 is set by matching device 40. When the power wave W11 is a modulation wave MW1, during the execution of step ST1, the load impedance of high-frequency power supply 36 can also be adjusted to a target impedance different from the output impedance of high-frequency power supply 36 as described above. Furthermore, when the power wave W11 is a modulation wave MW1, during the execution of step ST1, load power control can also be performed by high-frequency power supply 36 as described above.

[0150] When the power wave W11 is a continuous wave CW1, during the execution of step ST1, the load impedance of the high-frequency power supply 36 can also be matched with the output impedance of the high-frequency power supply 36. Alternatively, when the power wave W11 is a continuous wave CW1, similarly to the case where the power wave W11 is a modulated wave MW1, during the execution of step ST1, the load impedance of the high-frequency power supply 36 can also be adjusted to a target impedance different from the output impedance of the high-frequency power supply 36.

[0151] During the execution of the step ST1, the load impedance of the high-frequency power source 38 is set by the matcher 42. In the case where the power wave W21 is the modulated wave MW2, during the execution of the step ST1, the load impedance of the high-frequency power source 38 can also be adjusted to a target impedance different from the output impedance of the high-frequency power source 38 as described above. Further, in the case where the power wave W21 is the modulated wave MW2, during the execution of the step ST1, the load power control can also be executed by the high-frequency power source 38 as described above.

[0152] In the case where the power wave W21 is the continuous wave CW2, during the execution of the step ST1, the load impedance of the high-frequency power source 38 can also be matched to the output impedance of the high-frequency power source 38. Alternatively, in the case where the power wave W21 is the continuous wave CW2, during the execution of the step ST1, the load impedance of the high-frequency power source 38 can also be adjusted to a target impedance different from the output impedance of the high-frequency power source 36 as in the case where the power wave W21 is the modulated wave MW2.

[0153] In the step STJa, it is judged whether the power wave supplied in the preceding period PA of the two consecutive periods is a continuous wave. In the case where no continuous wave CW1 is supplied in the preceding period PA, i.e., a modulated wave MW1 is supplied, the step STA2 is supplied in the succeeding period PB of the two consecutive periods. In the case where the modulated wave MW1 is supplied in the preceding period PA and the continuous wave CW1 is supplied in the succeeding period PB, the step STA3 is executed in the succeeding period PB. On the other hand, in the case where the continuous wave CW1 is supplied in the preceding period PA, the step STB3 is executed in the succeeding period PB. In the case where the continuous wave CW1 is supplied in the preceding period PA and the modulated wave MW1 is supplied in the succeeding period PB, the step STB2 is executed in the preceding period PA.

[0154] Further, in the case where no continuous wave CW2 is supplied in the preceding period PA, i.e., a modulated wave MW2 is supplied, the step STA2 is executed in the succeeding period PB. In the case where the modulated wave MW2 is supplied in the preceding period PA and the continuous wave CW2 is supplied in the succeeding period PB, the step STA3 is executed in the succeeding period PB. In the case where the continuous wave CW2 is supplied in the preceding period PA, the step STB3 is executed in the succeeding period PB. In the case where the continuous wave CW2 is supplied in the preceding period PA and the modulated wave MW2 is supplied in the succeeding period PB, the step STB2 is executed in the preceding period PA.

[0155] In the case where the modulated wave MW1 is supplied in the preceding period PA, step STA2 is executed. In step STA2, the power wave of the succeeding period PB is supplied by the high-frequency power source 36. In the case where the power wave supplied by the high-frequency power source 36 in step STA2 is the continuous wave CW1, the load impedance of the high-frequency power source 36 is changed to the target impedance for the succeeding period PB in step STA3 after the start of the succeeding period PB, as described above. In the case where the power wave supplied by the high-frequency power source 36 in step STA2 is the modulated wave MW1, the load impedance of the high-frequency power source 36 can be set to the target impedance different from the output impedance of the high-frequency power source 36.

[0156] In addition, in the case where the modulated wave MW2 is supplied in the preceding period PA, step STA2 is executed. In step STA2, the power wave of the succeeding period PB is supplied by the high-frequency power source 38. In the case where the power wave supplied by the high-frequency power source 38 in step STA2 is the continuous wave CW2, the load impedance of the high-frequency power source 38 is changed to the target impedance for the succeeding period PB in step STA3 after the start of the succeeding period PB, as described above. In the case where the power wave supplied by the high-frequency power source 38 in step STA2 is the modulated wave MW2, the load impedance of the high-frequency power source 38 can be set to the target impedance different from the output impedance of the high-frequency power source 38.

[0157] In the case where the continuous wave CW1 is supplied in the preceding period PA, step STB3 is executed in the succeeding period PB. In step STB3, the power wave of the succeeding period PB is supplied by the high-frequency power source 36. In the case where the power wave supplied by the high-frequency power source 36 in step STB3 is the modulated wave MW1, step STB2 is executed in the preceding period PA before the start of the succeeding period PB. In step STB2, the load impedance of the high-frequency power source 36 is changed to the target impedance for the succeeding period PB, as described above. In the case where the power wave supplied by the high-frequency power source 36 in step STB3 is the continuous wave CW1, the load impedance of the high-frequency power source 36 can be matched to the output impedance of the high-frequency power source 36.

[0158] In the case where the continuous wave CW2 is supplied in the preceding period PA, step STB3 is executed in the succeeding period PB. In step STB3, the power wave of the succeeding period PB is supplied by the high-frequency power source 38. In the case where the power wave supplied by the high-frequency power source 38 in step STB3 is the modulated wave MW2, step STB2 is executed in the preceding period PA before the start of the succeeding period PB. In step STB2, the load impedance of the high-frequency power source 38 is changed to the target impedance for the succeeding period PB, as described above. In the case where the power wave supplied by the high-frequency power source 38 in step STB3 is the continuous wave CW2, the load impedance of the high-frequency power source 38 can be matched to the output impedance of the high-frequency power source 38.

[0159] In step STJb, it is determined whether or not an end condition is satisfied. In Figure 10 The end condition is satisfied in a case where the number of times of execution of the loop CY shown in FIG. 6 reaches a prescribed number of times. In a case where the end condition is not satisfied, the loop CY is repeatedly executed from step STJa. In a case where the end condition is satisfied, the method MT ends.

[0160] The above describes various exemplified embodiments, but is not limited to the above-described exemplified embodiments, and various additions, omissions, substitutions, and changes can be made. Furthermore, elements in different embodiments can be combined to form other embodiments.

[0161] For example, the plasma processing apparatus 1 is a capacitively coupled type plasma processing apparatus, but the idea of the present application can be applied to any plasma processing apparatus that can supply modulated high-frequency electric power from a high-frequency power source to an electrode. As such a plasma processing apparatus, for example, an inductively coupled type plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, a plasma processing apparatus that generates plasma using a surface wave such as a microwave can be cited.

[0162] In addition, with respect to the plasma processing apparatus 1, it is shown that both the high-frequency electric power RF1 and the high-frequency electric power RF2 are used for plasma processing, but only one of the high-frequency electric power RF1 and the high-frequency electric power RF2 can be used for plasma processing.

[0163] Next, experiments using the plasma processing apparatus 1 will be described. In the experiments, plasma was generated in the third mode in the plasma processing apparatus 1. In the experiments, as the power level of the high-frequency electric power RF2, both 400 W and 1000 W of power were used. Furthermore, in the experiments, values different from each of the above-described TL and ΔΓ2 were set. Other conditions in the experiments are shown below.

[0164] <Conditions>

[0165] Frequency of the high-frequency electric power RF1: 60 MHz

[0166] Power of the continuous wave CW1: 300 W

[0167] Frequency of the high-frequency electric power RF2: 40.68 MHz

[0168] Power of the modulated wave MW2 in the first sub-period SP11 and power of the continuous wave CW2 in the period P2: 400 W or 1000 W

[0169] Power of the modulated wave MW2 in the second sub-period SP12: 0 W

[0170] The modulation frequency of the modulated wave MW2 is 1kHz.

[0171] Duty cycle of modulated wave MW2: 90%

[0172] In the experiment, the V of the base 16 corresponding to the high-frequency electrical power RF2 was measured. PP V PP This is the peak-to-peak value of the voltage at base 16 corresponding to the high-frequency electrical power RF2. In the experiment, the voltage V produced by changing the electrical power supplied to base 16 from the modulated wave MW2 to the continuous wave CW2 was determined. PP The reduction in V relative to when no reflection was actually observed PP The percentage (%) (hereinafter referred to as the "reduction rate"). Table 1 shows the reduction rate when the power of the modulated wave MW2 in the first period SP11 and the power of the continuous wave CW2 in period P2 are set to 400W. Table 2 shows the reduction rate when the power of the modulated wave MW2 in the first period SP11 and the power of the continuous wave CW2 in period P2 are set to 1000W.

[0173] Table 1

[0174]

[0175] Table 2

[0176]

[0177] As shown in Tables 1 and 2, the experimental results show that when TL is set to 0.5 seconds or more and ΔΓ2 is set to 0.2 seconds or less, or when TL is set to 0.2 seconds or more and ΔΓ2 is set to 0.1 seconds or less, the reduction rate is less than 10%. Therefore, it is confirmed that reflection can be effectively suppressed when TL is set to 0.5 seconds or more and ΔΓ2 is set to 0.2 seconds or less, or when TL is set to 0.2 seconds or more and ΔΓ2 is set to 0.1 seconds or less. Furthermore, when TL is set to 0.5 seconds or more and ΔΓ2 is set to 0.05 seconds or less, the reduction rate is 0%. Therefore, it is confirmed that reflection is essentially non-existent when TL is set to 0.5 seconds or more and ΔΓ2 is set to 0.05 seconds or less.

[0178] Based on the above description, various embodiments of the invention have been described in this specification for illustrative purposes. It should be understood that various changes can be made without departing from the scope and spirit of the invention. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are given by the scope of the appended claims.

Claims

1. A plasma processing apparatus characterized by comprising: comprises: a chamber; an electrode; a high-frequency power source electrically connected to the electrode and configured to generate high-frequency electric power to be supplied to the electrode for plasma processing in the chamber; and a matcher connected between the high-frequency power source and the electrode and configured to set a load impedance as an impedance on a load side of the high-frequency power source, the high-frequency power source is configured to supply, in a preceding period of two consecutive periods, a power wave of one of a continuous wave having a stable and constant power level and a modulated wave in which two power levels are alternately and periodically repeatedly changed, to the electrode, and supply, in a succeeding period of the two consecutive periods, a power wave of the other of the continuous wave and the modulated wave to the electrode, the high-frequency power source generates the modulated wave in such a manner that a power level of the high-frequency electric power in a first sub-period of alternating first and second sub-periods is higher than a power level of the high-frequency electric power in the second sub-period, the matcher is configured to stepwise change the load impedance to a target impedance for the succeeding period by stepwise changing the load impedance in the period during which the continuous wave is supplied in the two consecutive periods, the matcher is configured to stepwise change the load impedance in the period during which the continuous wave is supplied so that an absolute value of a reflection coefficient of the high-frequency electric power is stepwise changed to a set target value for the succeeding period, the matcher is configured to stepwise change the load impedance so that the absolute value of the reflection coefficient of the high-frequency electric power is stepwise reduced to zero after the electric power supplied from the high-frequency power source to the electrode is switched from the modulated wave to the continuous wave.

2. The plasma processing apparatus according to claim 1, wherein: the matcher is configured to stepwise change the load impedance so that the absolute value of the reflection coefficient of the high-frequency electric power is stepwise increased to the set target value greater than zero before the electric power supplied from the high-frequency power source to the electrode is switched from the continuous wave to the modulated wave.

3. The plasma processing apparatus according to claim 2, wherein: the set target value is 0.3 or more and 0.5 or less.

4. The plasma processing apparatus according to any one of claims 1 to 3, wherein: the matcher is configured to stepwise change the absolute value of the reflection coefficient to the set target value for the succeeding period over consecutive multiple sub-periods in the period during which the continuous wave is supplied, a time length of each of the multiple sub-periods is set to be 0.5 seconds or more, and a difference between a target value of the absolute value of the reflection coefficient in one of any two consecutive sub-periods included in the multiple sub-periods and a target value of the absolute value of the reflection coefficient in the other sub-period is set to be 0.2 or less, or the time length is set to be 0.2 seconds or more, and the difference is set to be 0.1 or less. ​ 5. The plasma processing apparatus according to claim 4, wherein: the time length is set to 0.5 seconds or more, and the difference is set to 0.05 or less.

6. The plasma processing apparatus according to claim 1, wherein: the matcher is configured to be capable of adjusting a load impedance of the high-frequency power source in a period in which the modulated wave is supplied among the two successive periods to a target impedance different from an output impedance of the high-frequency power source, the load impedance being determined using a measured value of the load impedance in a monitoring period within the first sub-period.

7. The plasma processing apparatus according to claim 6, wherein: the monitoring period is a period that starts after a prescribed time length has elapsed from a start time of the first sub-period.

8. The plasma processing apparatus according to claim 6 or 7, wherein: the matcher is configured to be capable of determining the target impedance in accordance with a set target value of an absolute value of a reflection coefficient of the modulated wave in the period in which the modulated wave is supplied.

9. The plasma processing apparatus according to claim 8, wherein: the set target value of the absolute value of the reflection coefficient is 0.3 or more and 0.5 or less.

10. The plasma processing apparatus according to claim 6 or 7, wherein: the high-frequency power source is configured to be capable of adjusting a power level of the modulated wave so that a load power level and a target power level are close to or identical to each other, the load power being a difference between a power level of a traveling wave of the modulated wave and a power level of a reflected wave of the modulated wave.

11. A matching method executed in a plasma processing apparatus, the plasma processing apparatus including: a chamber; an electrode; a high-frequency power source electrically connected to the electrode, configured to be capable of generating high-frequency electric power to be supplied to the electrode for plasma processing in the chamber; and a matcher connected between the high-frequency power source and the electrode, configured to be capable of setting a load impedance as an impedance on a load side of the high-frequency power source, the matching method comprising: a step of supplying, in a preceding period among two successive periods, a power wave of one of a modulated wave and a continuous wave of the high-frequency electric power from the high-frequency power source to the electrode, the continuous wave being a wave having a stable and constant power level, the modulated wave being a wave in which two power levels are alternately and periodically changed, the modulated wave being generated in such a manner that a power level of the high-frequency electric power in a first sub-period among the first and second sub-periods is higher than a power level of the high-frequency electric power in a second sub-period; a step of supplying, in a succeeding period among the two successive periods, a power wave of the other of the modulated wave and the continuous wave of the high-frequency electric power to the electrode; and a step of stepwisely changing the load impedance to a target impedance for the succeeding period in a period in which the continuous wave is supplied among the two successive periods. ​ ​ ​ ​ ​ ​ ​ ​ ​ In the step of stepwise changing the load impedance, the load impedance is stepwise changed so that the absolute value of the reflection coefficient of the high-frequency electric power is stepwise changed to a set target value for the succeeding period, In the step of stepwise changing the load impedance after the electric power supplied from the high-frequency electric power source to the electrode is switched from the continuous wave to the modulated wave, the load impedance is stepwise changed so that the absolute value of the reflection coefficient of the high-frequency electric power is stepwise decreased to zero.

12. The matching method according to claim 11, wherein: In the step of stepwise changing the load impedance before the electric power supplied from the high-frequency electric power source to the electrode is switched from the continuous wave to the modulated wave, the load impedance is stepwise changed so that the absolute value of the reflection coefficient of the high-frequency electric power is stepwise increased to the set target value which is larger than zero.

13. The matching method according to claim 12, wherein: The set target value is 0.3 or more and 0.5 or less.

14. The matching method according to any one of claims 11 to 13, wherein: In the period during which the continuous wave is supplied, the load impedance is stepwise changed over a plurality of consecutive sub-periods so that the absolute value of the reflection coefficient is stepwise changed to the set target value for the succeeding period, a length of each of the sub-periods is set to be 0.5 seconds or more, and a difference between a target value of the absolute value of the reflection coefficient in one of any two consecutive sub-periods included in the plurality of sub-periods and a target value of the absolute value of the reflection coefficient in the other sub-period is set to be 0.2 or less, or the length is set to be 0.2 seconds or more, and the difference is set to be 0.1 or less.

15. The matching method according to claim 14, wherein: the length is set to be 0.5 seconds or more, and the difference is set to be 0.05 or less.

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