Plasma processing apparatus and matching method

Abstract

The present invention provides a technology for reducing reflection from a load after switching the power supplied to the electrode of a plasma processing device from one of a high-frequency modulated wave and a continuous wave to the other. A plasma processing apparatus according to one exemplary embodiment comprises a chamber, a high-frequency power source, an electrode, and a matching device. The high-frequency power source is electrically connected to the electrode. The matching device 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 power to the electrode. The modulated wave is generated by alternately increasing or decreasing the power level of the high-frequency power. The matching device changes the load impedance in steps up to a target impedance during the period when the continuous wave is supplied, either before or after the 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

Technology Field

[0001] An exemplary embodiment of the present disclosure relates to a plasma processing apparatus and a matching method. Background Technology

[0002] In the manufacture of electronic devices, a plasma processing apparatus is utilized. The plasma processing apparatus comprises a chamber, electrodes, a high-frequency power supply, and a matching unit. To generate plasma by exciting the gas inside the chamber, high-frequency power is applied to the electrodes from the high-frequency power supply. The matching unit is configured to match the impedance on the load side of the high-frequency power supply—that is, the load impedance—to the output impedance of the high-frequency power supply.

[0003] In a plasma processing apparatus, a technique has been proposed to supply high-frequency power, that is, a modulated wave of high-frequency power, to an electrode in which the power is alternately increased or decreased. Such a technique is described, for example, in the following patent documents 1 and 2. Prior art literature

[0004] Patent Document 1: Japanese Patent Publication No. 2015-90770 Patent Document 2: Japanese Patent Publication No. 2019-186099 The problem to be solved

[0005] The present disclosure provides a technique for reducing reflection from a load after switching the power supplied to the electrode of a plasma processing device from one of a high-frequency modulated wave and a continuous wave to the other. means of solving the problem

[0006] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus comprises a chamber, an electrode, a high-frequency power source, and a matching device. The high-frequency power source is electrically connected to the electrode. The high-frequency power source is configured to generate high-frequency power supplied to the electrode for plasma processing within the chamber. The matching device is connected between the high-frequency power source and the electrode. The matching device is configured to set a load impedance, which is the impedance on the load side of the high-frequency power source. The high-frequency power source is configured to supply a power wave of either a modulated wave or a continuous wave of high-frequency power to the electrode during the preceding period of two consecutive periods, and to supply a power wave of either a modulated wave or a continuous wave to the electrode during the subsequent period of two consecutive periods. The high-frequency power source generates a modulated wave such that the power level of the high-frequency power during the first period of alternating first and second periods is higher than the power level of the high-frequency power during the second period. The matching device is configured to gradually change the load impedance to the target impedance for the subsequent period during the period in which a continuous wave is supplied during two consecutive periods. Effects of the invention

[0007] According to one exemplary embodiment, it is possible to reduce reflection from the load after switching the power supplied to the electrode of the plasma processing device from one of the high-frequency power modulation wave and continuous wave to the other. Brief explanation of the drawing

[0008] FIG. 1 is a schematic drawing showing a plasma processing apparatus according to one exemplary embodiment. FIG. 2 is a diagram showing an example of a timing chart of a first high-frequency power and a second high-frequency power. FIG. 3 is a drawing showing a separate example of a timing chart of the first high-frequency power and the second high-frequency power. FIG. 4 is a drawing illustrating an example of the configuration of the first high-frequency power supply and the first matching unit of the plasma processing device shown in FIG. 1. FIG. 5 is a drawing showing an example of the configuration of a sensor of the first matching unit of the plasma processing device shown in FIG. 1. FIG. 6 is a drawing showing an example of the configuration of the second high-frequency power supply and the second matching unit of the plasma processing device shown in FIG. 1. FIG. 7 is a drawing showing an example of the configuration of a sensor of the second matching unit of the plasma processing device shown in FIG. 1. FIG. 8 is a diagram showing an example of a change in the absolute value of the reflection coefficient. FIG. 9 is a diagram showing a separate example of a change in the absolute value of the reflection coefficient. FIG. 10 is a flowchart of a matching method according to one exemplary embodiment. Specific details for implementing the invention

[0009] Various exemplary embodiments are described below.

[0010] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus comprises a chamber, an electrode, a high-frequency power source, and a matching device. The high-frequency power source is electrically connected to the electrode. The high-frequency power source is configured to generate high-frequency power supplied to the electrode for plasma processing within the chamber. The matching device is connected between the high-frequency power source and the electrode. The matching device is configured to set a load impedance, which is the impedance on the load side of the high-frequency power source. The high-frequency power source is configured to supply a power wave of either a modulated wave or a continuous wave of high-frequency power to the electrode during the preceding period of two consecutive periods, and to supply a power wave of either a modulated wave or a continuous wave to the electrode during the subsequent period of two consecutive periods. The high-frequency power source generates a modulated wave such that the power level of the high-frequency power during the first period of alternating first and second periods is higher than the power level of the high-frequency power during the second period. The matching device is configured to gradually change the load impedance to the target impedance for the subsequent period during the period in which a continuous wave is supplied during two consecutive periods.

[0011] In the above embodiment, the matching device gradually changes the load impedance to a target impedance for a subsequent period during the period when a continuous wave is supplied before or after the power supplied to the electrode from the high-frequency power source is switched from one power wave to another. Accordingly, the matching device can track the load impedance that must be set after the power supplied to the electrode from the high-frequency power source is switched from one power wave to another. Accordingly, it is possible to reduce reflection after the power supplied to the electrode from the high-frequency power source is switched from one of the modulated wave and the continuous wave to the other.

[0012] In one exemplary embodiment, the matching device may perform a stepwise change of the load impedance during the period in which a continuous wave is supplied by changing the absolute value of the reflection coefficient of the high-frequency power stepwise to a set target value for a subsequent period.

[0013] In one exemplary embodiment, the matching device may be configured to change the load impedance in steps so that, after the power supplied to the electrode from the high-frequency power source is converted from a modulated wave to a continuous wave, the absolute value of the reflection coefficient of the high-frequency power is reduced in steps to zero.

[0014] In one exemplary embodiment, the matching device may perform a stepwise change of the load impedance before the power supplied to the electrode is switched from a continuous wave to a modulated wave by gradually increasing the absolute value of the reflection coefficient of the high-frequency power to a set target value greater than zero. The set target value may be 0.3 or higher and 0.5 or lower.

[0015] In one exemplary embodiment, the matching device may be configured to gradually change the absolute value of the reflection coefficient during the period in which the continuous wave is supplied to a set target value for a subsequent period. The time 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 time length may be set to 0.2 seconds or more, and the difference may be set to 0.1 or less. The time length may be set to 0.5 seconds or more, and the difference may be set to 0.05 or less.

[0016] In one exemplary embodiment, the matching device may be configured to adjust the load impedance of the high-frequency power supply to a target impedance different from the output impedance of the high-frequency power supply during the period in which the modulation wave is supplied during two consecutive periods. The load impedance of the high-frequency power supply is determined by the measured value of the load impedance during the monitoring period within the first period. According to this embodiment, reflection from the load to the modulation wave can be reduced during the period in which the modulation wave is supplied.

[0017] In one exemplary embodiment, the monitoring period may be a period that begins after a predetermined length of time has elapsed from the start of the first part period.

[0018] In one exemplary embodiment, the matching device may be configured to specify the target impedance from a set target value of the absolute value of the reflection coefficient of the modulation wave during the period in which the modulation wave is supplied. In one exemplary embodiment, this set target value may be 0.3 or more and 0.5 or less.

[0019] In one exemplary embodiment, the high-frequency power supply may be configured to adjust the power level of the high-frequency power so that the load power level during the period in which the modulation wave is supplied approaches or matches the target power level. The load power level is the difference between the power level of the propagating wave of the modulation wave and the power level of the reflected wave of the modulation wave. If the target impedance is different from the output impedance of the high-frequency power supply, reflection occurs. According to this embodiment, even if reflection occurs, the modulation wave of the target power level can be coupled to the plasma.

[0020] In a separate exemplary embodiment, a matching method is provided. The matching method is performed in a plasma processing apparatus. The plasma processing apparatus comprises a chamber, an electrode, a high-frequency power source, and a matching device. The high-frequency power source is electrically connected to the electrode. The high-frequency power source is configured to generate high-frequency power supplied to the electrode for plasma processing within the chamber. The matching device is connected between the high-frequency power source and the electrode and is configured to set a load impedance, which is the impedance on the load side of the high-frequency power source. The matching method includes a process of supplying a power wave of either a modulated wave or a continuous wave of high-frequency power from the high-frequency power source to the electrode during a preceding period among two consecutive periods. The modulated wave is generated such that the power level of the high-frequency power during the first period among alternating first and second periods is higher than the power level of the high-frequency power during the second period. The matching method further includes a process of supplying the other power wave of either a modulated wave or a continuous wave of high-frequency power to the electrode during a subsequent period among two consecutive periods. The matching method further includes a process of gradually changing the load impedance to a target impedance for a subsequent period during the period in which a continuous wave is supplied during two consecutive periods.

[0021] In one exemplary embodiment, in a process of changing the load impedance in steps, the load impedance may be changed in steps such that the absolute value of the reflection coefficient of high-frequency power is changed in steps to a set target value for a subsequent period.

[0022] In one exemplary embodiment, after the power supplied to the electrode is switched from a modulated wave to a continuous wave, the load impedance may be changed in steps to gradually reduce the absolute value of the reflection coefficient of the high-frequency power to zero.

[0023] In one exemplary embodiment, before the power supplied to the electrode is switched from a continuous wave to a modulated wave, the load impedance may be changed stepwise to increase the absolute value of the reflection coefficient of the high-frequency power stepwise to a set target value greater than zero. The set target value may be 0.3 or greater and 0.5 or less.

[0024] In one exemplary embodiment, during the period in which a continuous wave is supplied, the load impedance may be changed stepwise so as to change the absolute value of the reflection coefficient stepwise through a plurality of consecutive sub-periods to a set target value for a subsequent period. The time 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 time length may be set to 0.2 seconds or more, and the difference may be set to 0.1 or less. The time length may be set to 0.5 seconds or more, and the difference may be set to 0.05 or less.

[0025] Hereinafter, various embodiments will be described in detail with reference to the drawings. In addition, identical or equivalent parts in each drawing are denoted by the same reference numeral.

[0026] FIG. 1 is a schematic drawing of a plasma processing apparatus according to one exemplary embodiment. The plasma processing apparatus (1) shown in FIG. 1 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus (1) is equipped with a chamber (10). The chamber (10) provides an internal space therein.

[0027] The chamber (10) includes a chamber body (12). The chamber body (12) has a roughly cylindrical shape. The internal space of the chamber (10) is provided on the inside of the chamber body (12). The chamber body (12) is formed of a material called aluminum. A plasma-resistant film is formed on the inner wall surface of the chamber body (12). This film may be a ceramic film formed by an anodic oxidation treatment or a film formed of yttrium oxide. The chamber body (12) is grounded. An opening (12p) is formed on the side wall of the chamber body (12). A substrate (W) passes through the opening (12p) when being transported between the internal space of the chamber (10) and the outside of the chamber (10). The opening (12p) can be opened and closed by a gate valve (12g). The gate valve (12g) is provided along the side wall of the chamber body (12).

[0028] An insulating plate (13) is provided on the bottom portion of the chamber body (12). The insulating plate (13) is formed of, for example, ceramic. A support (14) is provided on the insulating plate (13). The support (14) has a roughly disc shape. The support (14) supports a susceptor (16) provided thereon. The susceptor (16) is provided within the chamber (10). The susceptor (16) is formed of a conductive material called aluminum. The susceptor (16) constitutes a lower electrode.

[0029] The susceptor (16) supports the electrostatic chuck (18) provided thereon. The electrostatic chuck (18) is provided within the chamber (10). The electrostatic chuck (18) is configured to hold a substrate (W) placed thereon. The electrostatic chuck (18) has a body and an electrode (20). The body of the electrostatic chuck (18) is formed of a dielectric material and has a roughly disc shape. The electrode (20) is a conductive film and is provided within the body of the electrostatic chuck (18). A DC power source (24) is electrically connected to the electrode (20) through a switch (22). When a DC voltage from the DC power source (24) is applied to the electrode (20), an electrostatic attraction is generated between the substrate (W) and the electrostatic chuck (18). Due to the generated electrostatic attraction, the substrate (W) is pulled toward the electrostatic chuck (18) and held by the electrostatic chuck (18).

[0030] The susceptor (16) and the electrostatic chuck (18) constitute a substrate support. The substrate support supports an edge ring (26) mounted thereon. The edge ring (26) is positioned to surround the edge of the substrate (W). That is, the substrate (W) is placed on the electrostatic chuck (18) within the area surrounded by the edge ring (26). The outer surface of each of the susceptor (16) and the support (14) is covered by a cylindrical inner wall member (28). The inner wall member (28) is formed of, for example, quartz.

[0031] A flow path (14f) is formed inside the support (14). The flow path (14f) extends spirally with respect to a central axis extending vertically, for example. A heat exchange medium (cw) (e.g., a refrigerant called cooling water) is supplied to the flow path (14f) through a pipe (32a) from a supply device (e.g., a chiller unit) provided outside the chamber (10). The heat exchange medium supplied to the flow path (14f) is returned to the supply device through a pipe (32b). The temperature of the substrate (W) is adjusted by adjusting the temperature of the heat exchange medium by the supply device. Additionally, the plasma processing device (1) provides a gas supply line (34). The gas supply line (34) is provided to supply a heat transfer gas (e.g., He gas) to the gap between the upper surface of the electrostatic chuck (18) and the lower surface of the substrate (W).

[0032] The plasma processing device (1) may be equipped with one or more high-frequency power sources. In one embodiment, the plasma processing device (1) is equipped with a first high-frequency power source [i.e., high-frequency power source (36)] and a second high-frequency power source [i.e., high-frequency power source (38)]. The high-frequency power source (36) is connected to the susceptor (16) (i.e., lower electrode) through a conductor (44) (e.g., a feed rod) and a first matching device [i.e., a matching device (40)]. The high-frequency power source (38) is connected to the susceptor (16) (i.e., lower electrode) through a conductor (44) and a second matching device [i.e., a matching device (42)]. Additionally, the high-frequency power source (36) may be connected to the upper electrode, which will be described later, through the matching device (40), rather than to the lower electrode. The plasma processing device (1) does not need to have one of the sets of the high-frequency power supply (36) and the matching device (40) and the high-frequency power supply (38) and the matching device (42).

[0033] The high-frequency power supply (36) is configured to generate a first high-frequency power [i.e., high-frequency power (RF1)] for plasma processing within the chamber (10). The high-frequency power (RF1) is primarily used for generating plasma. The fundamental frequency (f) of the high-frequency power (RF1) B1 ) is, for example, 100 MHz. The high-frequency power supply (38) is configured to generate a second high-frequency power [i.e., high-frequency power (RF2)] for plasma processing within the chamber (10). The frequency of the high-frequency power (RF2) is lower than the frequency of the high-frequency power (RF1). The fundamental frequency (f) of the high-frequency power (RF2) B2 ) is, for example, 13.56 MHz.

[0034] The matching unit (40) has a circuit for setting a load impedance, which is the impedance of the load side (e.g., lower electrode side) of the high-frequency power source (36). The matching unit (42) has a circuit for setting a load impedance, which is the impedance of the load side (lower electrode side) of the high-frequency power source (38). Each of the matching unit (40) and the matching unit (42) may be an electronically controlled matching unit. Details regarding each of the matching unit (40) and the matching unit (42) will be described later.

[0035] The matching unit (40) and the conductor (44) form part of the power supply line (43). High-frequency power (RF1) is supplied to the susceptor (16) through the power supply line (43). The matching unit (42) and the conductor (44) form part of the power supply line (45). High-frequency power (RF2) is supplied to the susceptor (16) through the power supply line (45).

[0036] The plasma processing device (1) further comprises an upper electrode (46). The upper electrode (46) forms the ceiling portion of the chamber (10). The upper electrode (46) is provided to close the opening at the top of the chamber body (12). The internal space of the chamber (10) includes a processing area (PS). The processing area (PS) is the space between the upper electrode (46) and the susceptor (16). The plasma processing device (1) generates plasma in the processing area (PS) by means of a high-frequency electric field generated between the upper electrode (46) and the susceptor (16). The upper electrode (46) is grounded. Additionally, if the high-frequency power supply (36) is connected to the upper electrode (46) rather than the lower electrode through a matching device (40), the upper electrode (46) is not grounded, and the upper electrode (46) and the chamber body (12) are electrically separated.

[0037] The upper electrode (46) has a ceiling plate (48) and a support (50). A plurality of gas ejection holes (48a) are formed in the ceiling plate (48). The ceiling plate (48) is formed of a silicon-based material, such as Si or SiC. The support (50) is a member that detachably supports the ceiling plate (48), is formed of a conductor called aluminum, and has a plasma-resistant film formed on its surface.

[0038] A gas buffer chamber (50b) is formed inside the support body (50). Additionally, a plurality of gas holes (50a) are formed in the support body (50). Each of the plurality of gas holes (50a) extends from the gas buffer chamber (50b) and communicates with a plurality of gas ejection holes (48a). A gas supply pipe (54) is connected to the gas buffer chamber (50b). A gas source (56) is connected to the gas supply pipe (54) through a flow controller (58) (e.g., a mass flow controller) and an opening / closing valve (60). Gas from the gas source (56) is supplied to the internal space of the chamber (10) through the flow controller (58), the opening / closing valve (60), the gas supply pipe (54), the gas buffer chamber (50b), and the plurality of gas ejection holes (48a). The flow rate of gas supplied from the gas source (56) to the internal space of the chamber (10) is controlled by a flow rate controller (58).

[0039] Below the side wall between the susceptor (16) and the chamber body (12), an exhaust port (12e) is provided in the bottom portion of the chamber body (12). An exhaust pipe (64) is connected to the exhaust port (12e). The exhaust pipe (64) is connected to an exhaust device (66). The exhaust device (66) has a pressure regulator called an automatic pressure control valve and a vacuum pump called a turbo molecular pump. The exhaust device (66) reduces the internal space of the chamber (10) to a specified pressure.

[0040] The plasma processing device (1) further comprises a main control unit (70). The main control unit (70) includes one or more microcomputers. The main control unit (70) may have a processor, a memory device called memory, an input device called a keyboard, a display device, a signal input / output interface, etc. The processor of the main control unit (70) executes software (program) stored in the memory device and controls the individual operation of each part of the plasma processing device (1) and the operation (sequence) of the entire plasma processing device (1) according to recipe data. The main control unit (70) controls, for example, a high-frequency power supply (36), a high-frequency power supply (38), a matching device (40), a matching device (42), a flow rate controller (58), an opening / closing valve (60), an exhaust device (66), etc.

[0041] When plasma processing is performed in the plasma processing device (1), first, the gate valve (12g) is opened. Subsequently, the substrate (W) is introduced into the chamber (10) via the opening (12p) and placed on the electrostatic chuck (18). Then, the gate valve (12g) is closed. Subsequently, processing gas is supplied from the gas source (56) to the internal space of the chamber (10), and the exhaust device (66) is operated so that the pressure in the internal space of the chamber (10) is set to a specified pressure. In addition, high-frequency power (RF1) and / or high-frequency power (RF2) is supplied to the susceptor (16). In addition, a DC voltage from the DC power source (24) is applied to the electrode (20) of the electrostatic chuck (18), and the substrate (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, plasma is generated within the processing area (PS).

[0042] Hereinafter, reference is made to FIG. 2 and FIG. 3 together with FIG. 1. FIG. 2 is a diagram showing an example of a timing chart of a first high-frequency power and a second high-frequency power. FIG. 3 is a diagram showing a separate example of a timing chart of a first high-frequency power and a second high-frequency power. A plasma processing apparatus (1) is configured to use at least one of a modulation wave (MW1) of high-frequency power (RF1) or a modulation wave (MW2) of high-frequency power (RF2) for plasma processing within a chamber (10) during a period (P1). The modulation wave (MW1) is generated by a high-frequency power source (36). The modulation wave (MW2) is generated by a high-frequency power source (38). As indicated by the dotted line in FIG. 2 and FIG. 3, a continuous wave (CW1) of high-frequency power (RF1) or a continuous wave (CW2) of high-frequency power (RF2) may be used during a period (P1). The continuous wave (CW1) is generated by the high-frequency power supply (36). The continuous wave (CW2) is generated by the high-frequency power supply (38). The mode in which the modulation wave (MW1) and the modulation wave (MW2) are used during the period (P1) is the first mode. The mode in which the modulation wave (MW1) and the continuous wave (CW2) are used during the period (P1) is the second mode. The mode in which the continuous wave (CW1) and the modulation wave (MW2) are used during the period (P1) is the third mode.

[0043] The period (P1) includes an alternating first sub-period (SP11) and a second sub-period (SP12). A modulated wave (MW1) is generated by a high-frequency power source (36) such that the power level of the high-frequency power (RF1) in the first sub-period (SP11) is higher than the power level of the high-frequency power (RF1) in the second sub-period (SP12). The power level of the high-frequency power (RF1) in the second sub-period (SP12) may be 0[W]. A modulated wave (MW2) is generated by a high-frequency power source (38) such that the power level of the high-frequency power (RF2) in the first sub-period (SP11) is higher than the power level of the high-frequency power (RF2) in the second sub-period (SP12). The power level of the high-frequency power (RF2) in the second sub-period (SP12) may be 0[W].

[0044] The first sub-period (SP11) and the subsequent second sub-period (SP12) constitute a cycle (CP). The ratio that the first sub-period (SP11) occupies in the cycle (CP), i.e., the duty cycle, may be any value. For example, the duty cycle can be controlled to a value within the range of 10% or more and 90% or less. In addition, the reciprocal of the cycle (CP), i.e., the modulation frequency, can be controlled to any frequency. However, the modulation frequency is the fundamental frequency (f B1 ) and fundamental frequency (f B2 It is lower than ). The modulation frequency may be, for example, a frequency within the range of 0.1 kHz or higher and 100 kHz or lower.

[0045] Additionally, the plasma processing device (1) is configured to use a continuous wave (CW1) and a continuous wave (CW2) during a period (P2). That is, high-frequency power (RF1) and high-frequency power (RF2) are supplied continuously between the start time of the period (P2) and the end time of the period (P2). The time length of the period (P2) is longer than the time length of the cycle (CP).

[0046] Periods (P1) and (P2) are two consecutive periods. As shown in FIG. 2, among the two consecutive periods, period (P1) may be the preceding period (PA) and period (P2) may be the subsequent period (PB). Alternatively, as shown in FIG. 3, among the two consecutive periods, period (P2) may be the preceding period (PA) and period (P1) may be the subsequent period (PB). Periods (P1) and (P2) may be repeated alternately. That is, the high-frequency power source (36) supplies a power wave (W11) during the preceding period (PA). The power wave (W11) is either a modulated wave (MW1) or a continuous wave (CW1). The high-frequency power source (36) supplies either the power wave (W11) or the power wave (W12) during the subsequent period (PB). The power wave (W12) is the other of the modulated wave (MW1) and the continuous wave (CW1). The high-frequency power source (38) supplies the power wave (W21) during the preceding period (PA). The power wave (W21) is one of the modulated wave (MW2) and the continuous wave (CW2). The high-frequency power source (38) supplies the power wave (W21) or the power wave (W22) during the subsequent period (PB). The power wave (W22) is the other of the modulated wave (MW2) and the continuous wave (CW2). During the subsequent period (PB), at least one of the power wave (W12) or the power wave (W22) is supplied.

[0047] Hereinafter, with reference to FIGS. 4 to 7, the high-frequency power supply (36), the matching unit (40), the high-frequency power supply (38), and the matching unit (42) will be described in detail. FIG. 4 is a drawing showing an example of the configuration of the first high-frequency power supply and the first matching unit of the plasma processing device shown in FIG. 1. FIG. 5 is a drawing showing an example of the configuration of the sensor of the first matching unit of the plasma processing device shown in FIG. 1. FIG. 6 is a drawing showing an example of the configuration of the second high-frequency power supply and the second matching unit of the plasma processing device shown in FIG. 1. FIG. 7 is a drawing showing an example of the configuration of the sensor of the second matching unit of the plasma processing device shown in FIG. 1.

[0048] As shown in FIG. 4, in one embodiment, the high-frequency power supply (36) has an oscillator (36a), a power amplifier (36b), a power sensor (36c), and a power control unit (36e). The power control unit (36e) is composed of a processor called a CPU. The power control unit (36e) controls the oscillator (36a), the power amplifier (36b), and the power sensor (36c) by applying a control signal to each of the oscillator (36a), the power amplifier (36b), and the power sensor (36c). The power control unit (36e) generates a control signal applied to each of the oscillator (36a), the power amplifier (36b), and the power sensor (36c) using a signal applied from the main control unit (70) and a signal applied from the power sensor (36c).

[0049] The signal provided from the main control unit (70) to the power control unit (36e) includes a first frequency setting signal and a mode setting signal. The first frequency setting signal is a signal that specifies the setting frequency of the high frequency power (RF1). The mode setting signal is a signal that specifies a selected mode among the first to third modes. When the first mode or the second mode is specified, the signal provided from the main control unit (70) to the power control unit (36e) further includes a first modulation setting signal. The first modulation setting signal is a signal that specifies the modulation frequency and duty ratio of the modulation wave (MW1). Additionally, the first modulation setting signal is also a signal that specifies the power level of the modulation wave (MW1) in the first sub-period (SP11) and the power level of the modulation wave (MW1) in the second sub-period (SP12). When a third mode is specified, the signal given from the main control unit (70) to the power control unit (36e) further includes a first power level setting signal that specifies the power of the continuous wave (CW1).

[0050] The power control unit (36e) is a set frequency [e.g., basic frequency (f)] specified by the first frequency setting signal. B1The oscillator (36a) is controlled to output a high-frequency signal having )]. The output of the oscillator (36a) is connected to the input of the power amplifier (36b). The power amplifier (36b) generates high-frequency power (RF1) by amplifying the high-frequency signal output from the oscillator (36a). The power amplifier (36b) is controlled by the power control unit (36e).

[0051] When the first mode or the second mode is specified, the power control unit (36e) controls the power amplifier (36b) to generate a modulated wave (MW1) from a high-frequency signal according to the first modulation setting signal during the period (P1). When the first mode or the second mode is specified, the power control unit (36e) controls the power amplifier (36b) to generate a continuous wave (CW1) from a high-frequency signal according to the first power level setting signal during the period (P2). Additionally, when the third mode is specified, the power control unit (36e) controls the power amplifier (36b) to generate a continuous wave (CW1) from a high-frequency signal according to the first power level setting signal during the periods (P1) and (P2).

[0052] A power sensor (36c) is provided at the rear end of the power amplifier (36b). The power sensor (36c) has a directional coupler, a traveling wave detector, and a reflected wave detector. The directional coupler provides a portion of the traveling wave of the high-frequency power (RF1) to the traveling wave detector and provides the reflected wave to the reflected wave detector. A first frequency-specific signal specifying the set frequency of the high-frequency power (RF1) is provided to the power sensor (36c) from the power control unit (36e). The traveling wave detector is a measured value of the power level of the component having the same frequency as the set frequency specified by the first frequency-specific signal among the total frequency components of the traveling wave, that is, a measured value of the power level of the traveling wave (P f11 Generates ). Measurement value (P f11 ) is assigned to the power control unit (36e).

[0053] The first frequency-specific signal is also applied to the reflected wave detector from the power control unit (36e). The reflected wave detector is a measured value of the power level of a component having the same frequency as the set frequency specified by the first frequency-specific signal among the total frequency components of the reflected wave, i.e., a measured value of the power level of the reflected wave (P r11 Generates ). Measurement value (P r11 ) is assigned to the power control unit (36e). In addition, the reflected wave detector is a measured value of the total power level of the entire frequency component of the reflected wave, i.e., a measured value of the power level of the reflected wave (P r12 Generates ). Measurement value (P r12 ) is provided to the power control unit (36e) for protection of the power amplifier (36b).

[0054] In one embodiment, the high-frequency power supply (36) may perform load power control during the period (P1). That is, the high-frequency power supply (36) may adjust the power level of the high-frequency power (RF1) so that the load power level of the high-frequency power (RF1) during the period (P1) approaches or matches a specified target power level. The power control unit (36e) may control the power amplifier (36b) in the load power control of the high-frequency power supply (36).

[0055] In load power control when a first mode or a second mode is specified, the power control unit (36e) can control the power amplifier (36b) to adjust the power level of the modulation wave (MW1) in the first sub-period (SP11). The power level of the modulation wave (MW1) in the first sub-period (SP11) is adjusted to bring the load power level (PL11) in the monitor period (MP1) closer to or match the specified target power level.

[0056] The monitoring period (MP1) is a period within the first sub-period (SP11). The monitoring period (MP1) may be a period that begins after a predetermined length of time has elapsed from the start of the first sub-period (SP11). The monitoring period (MP1) is specified by the main control unit (70). Load power level (P L11 ) is the difference between the power level of the traveling wave of the high-frequency power (RF1) during the monitor period (MP1) and the power level of the reflected wave of the high-frequency power (RF1) during the monitor period (MP1). Load power level (P L11 ) is the measured value (P) during the monitor period (MP1). f11 ) and measured value (P r11 It is obtained as the difference of ). Load power level (P L11 ) is the measured value (P) during the monitor period (MP1). f11 The average value and measured value (P r11 It may be calculated as the difference in the average values ​​of ). Or, load power level (P L11 ) is a measured value (P) during multiple monitor periods (MP1). f11 The moving average of ) and the measured value (P r11 It may be calculated as the difference of the moving average values ​​of ).

[0057] If the power level of the modulated wave (MW1) in the second sub-period (SP12) is not 0[W], the high-frequency power supply (36) may perform load power control of the modulated wave (MW1) in the second sub-period (SP12). In this load power control, the power control unit (36e) may 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) is the load power level (P) in the monitor period (MP2). L12 ) is adjusted to approach or match the specified target power level.

[0058] The monitor period (MP2) may be a period that coincides with the second sub-period (SP12). Alternatively, the monitor period (MP2) may be a period within the second sub-period (SP12) and may be a period that begins after a predetermined length of time has elapsed from the start of the second sub-period (SP12). The monitor period (MP2) is specified by the main control unit (70). Load power level (P L12 ) is the difference between the power level of the traveling wave of the high-frequency power (RF1) during the monitor period (MP2) and the power level of the reflected wave of the high-frequency power (RF1) during the monitor period (MP2). Load power level (P L12 ) is the measured value (P) during the monitor period (MP2). f11 ) and measured value (P r11 It is obtained as the difference of ). Load power level (P L12 ) is the measured value (P) during the monitor period (MP2). f11 The average value and measured value (P r11 It may be calculated as the difference in the average values ​​of ). Or, load power level (P L12 ) is a measured value (P) during multiple monitor periods (MP2). f11 The moving average of ) and the measured value (P r11 It may be calculated as the difference of the moving average values ​​of ).

[0059] Even when the third mode is specified, the high-frequency power supply (36) may perform load power control. In load power control when the third mode is specified, the power control unit (36e) may control the power amplifier (36b) to adjust the power level of the continuous wave (CW1) during the period (P1). The power level of the continuous wave (CW1) during the period (P1) is the load power level (P1) during the monitor period (MP1). L11 Load power level (P) during ) and monitor period (MP2) L12 The average value of ) is adjusted to match or approach a specified target power level.

[0060] The matching device (40) is configured to set the load impedance of the high-frequency power supply (36), i.e., the load impedance. In each of the first and second modes, the matching device (40) may set the load impedance of the high-frequency power supply (36) during the period (P1) to a target impedance different from the output impedance of the high-frequency power supply (36). The load impedance of the high-frequency power supply (36) during the period (P1) may be determined by the measured value of the load impedance of the high-frequency power supply (36) during the monitoring period (MP1).

[0061] In the third mode, the matching device (40) may match the load impedance of the high-frequency power supply (36) during the period (P1) to the output impedance of the high-frequency power supply (36). Alternatively, the matching device (40) may, in the third mode as in the first and second modes, set the load impedance of the high-frequency power supply (36) during the period (P1) to a target impedance different from the output impedance of the high-frequency power supply (36).

[0062] The matching device (40) changes the load impedance of the high-frequency power source (36) in stages to the target impedance for the subsequent period (PB) during the period (P2) in each of the first mode and the second mode. That is, the matching device (40) is configured to change the load impedance of the high-frequency power source (36) in stages to the target impedance for the subsequent period (PB) during the period (P2) before or after the power generated by the high-frequency power source (36) is switched from the power wave (W11) to the power wave (W12).

[0063] The matching device (40) changes the load impedance of the high-frequency power supply (36) in stages so that, in each of the first and second modes, as shown in FIG. 8 and FIG. 9, the absolute value (|Γ1|) of the reflection coefficient (Γ1) in the period (P2) is changed in stages to a set target value for the subsequent period (PB). As shown in FIG. 8, when the subsequent period (PB) in each of the first and second modes is the period (P2), the set target value of the absolute value (|Γ1|) of the reflection coefficient (Γ1) for the subsequent period (PB) may be zero. As shown in FIG. 9, when the subsequent period (PB) in each of the first and second modes is the period (P1), the set target value of the absolute value (|Γ1|) of the reflection coefficient (Γ1) for the subsequent period (PB) is greater than zero, for example, 0.3 or greater and 0.5 or less.

[0064] Period (P2) includes a plurality of consecutive sub-periods (SP). The plurality of sub-periods (SP) include sub-periods (SP1, SP2, ····, SP N ...includes ). The matching device (40) includes sub-periods (SP1, SP2, ..., SP2) in the period (P2). N The load impedance of the high-frequency power supply (36) can be changed stepwise so that the absolute value (|Γ1|) of the reflection coefficient (Γ1) is changed stepwise to a target value for the subsequent period (PB). As shown in FIG. 8, when the subsequent period (PB) is period (P2), the matching device (40) [initiates] the sub-periods (SP1, SP2, ····, SP1) within period (P2) after the start of the subsequent period (PB) [period (P2)]. N The load impedance of the high-frequency power supply (36) is changed stepwise through ). As shown in FIG. 9, when the subsequent period (PB) is period (P1), the matching device (40) has a sub-period (SP1, SP2, ····, SP2) within the period (P2) prior to the start of the subsequent period (PB) [period (P1)]. NThe load impedance of the high-frequency power supply (36) is changed stepwise through ). The period (P2) is the sub-period [SP (N+1) Includes ] additionally. Sub-period [SP (N+1) ] is, bookkeeping period (SP N It is a period continuous with ). The matching device (40) is, sub-period [SP (N+1) The load impedance of the high-frequency power supply (36) is set so that the absolute value (|Γ1|) of the reflection coefficient (Γ1) in ] is set as the target value for the subsequent period (PB). Below, the sub-periods [SP1, SP2, ····, SP N , SP (N+1) Each of ] is the book period (SP i There are cases where it is called ). "i" is an index that is an integer greater than or equal to 1 and less than or equal to N+1.

[0065] In the third mode, the matching device (40) may match the load impedance of the high-frequency power supply (36) during the period (P2) to the output impedance of the high-frequency power supply (36). In the third mode, just as in the first and second modes, the matching device (40) may also change the load impedance of the high-frequency power supply (36) during the period (P2) in stages up to the target impedance for the subsequent period (PB).

[0066] In one embodiment, the matching device (40) has a matching circuit (40a), a sensor (40b), a controller (40c), an actuator (40d), and an actuator (40e), as shown in FIG. 4. The matching circuit (40a) may include a variable reactance element (40g) and a variable reactance element (40h). Each of the variable reactance element (40g) and the variable reactance element (40h) is, for example, a variable capacitor. Additionally, the matching circuit (40a) may further include an inductor, etc.

[0067] The controller (40c) operates under the control of the main control unit (70). The controller (40c) adjusts the load impedance of the high-frequency power supply (36) according to the measured value of the load side impedance (i.e., load impedance) of the high-frequency power supply (36) provided by the sensor (40b). The controller (40c) adjusts the load impedance of the high-frequency power supply (36) by controlling the actuator (40d) and the actuator (40e) to adjust the reactance of the variable reactance element (40g) and the variable reactance element (40h), respectively. The actuator (40d) and the actuator (40e) are, for example, motors.

[0068] The sensor (40b) is configured to acquire a measured value of the load impedance of the high-frequency power supply (36). In one embodiment, the measured value of the load impedance of the high-frequency power supply (36) is acquired as a moving average value. As shown in FIG. 5, the sensor (40b) may have a current detector (102A), a voltage detector (104A), filters (106A and 108A), an average value calculator (110A and 112A), a moving average value calculator (114A and 116A), and an impedance calculator (118A).

[0069] The voltage detector (104A) detects the voltage waveform of the high-frequency power (RF1) transmitted over the power supply line (43) and outputs a voltage waveform analog signal representing the voltage waveform. This voltage waveform analog signal is input to a filter (106A). The filter (106A) generates a voltage waveform digital signal by digitizing the input voltage waveform analog signal. The filter (106A) receives the first frequency specification signal from the power control unit (36e) and generates a filtered voltage waveform signal by extracting only the frequency component corresponding to the frequency specified by the first frequency specification signal from the voltage waveform digital signal. The filter (106A) may be configured as an FPGA (Field Programmable Gate Array).

[0070] The filtered voltage waveform signal generated by the filter (106A) is output to the average value calculator (110A). The average value calculator (110A) receives a monitor period setting signal from the main control unit (70). The average value calculator (110A) calculates the average value of the voltage within the period specified by the monitor period setting signal from the filtered voltage waveform signal. The average value calculator (110A) calculates the average value of the voltage (V) for each monitor period (MP1) as the average value of the voltage. A11 ) is calculated. When a third mode is specified, the average value calculator (110A) calculates the average value of the voltage for each monitor period (MP2) as the average value of the voltage (V A12 It is also possible to obtain more ). In addition, the average value calculator (110A) may be configured, for example, as an FPGA (Field Programmable Gate Array).

[0071] The moving average value calculator (114A) is a plurality of already obtained average values ​​(V A11 The average value (V) obtained from the voltage of the high-frequency power (RF1) during the closest and predetermined number of monitor periods (MP1) among ) A11 The moving average value of ) (V MA11 Calculate the moving average value (V MA11 ) is output to the impedance calculator (118A).

[0072] In the third mode, the moving average value calculator (114A) has a plurality of already obtained average values ​​(V A12 The average value (V) obtained from the voltage of the high-frequency power (RF1) during the closest and predetermined number of monitor periods (MP2) among ) A12 The moving average value of ) (V MA12 You may calculate more ). Moving average value (V MA12 ) is output to the impedance calculator (118A).

[0073] The current detector (102A) detects the current waveform of the high-frequency power (RF1) transmitted over the power supply line (43) and outputs a current waveform analog signal representing the current waveform. This current waveform analog signal is input to a filter (108A). The filter (108A) generates a current waveform digital signal by digitizing the input current waveform analog signal. The filter (108A) receives the first frequency specification signal from the power control unit (36e) and generates a filtered current waveform signal by extracting only the frequency component corresponding to the frequency specified by the first frequency specification signal from the current waveform digital signal. The filter (108A) may be configured, for example, as an FPGA (Field Programmable Gate Array).

[0074] The filtered current waveform signal generated by the filter (108A) is output to the average value calculator (112A). The average value calculator (112A) receives a monitor period setting signal from the main control unit (70). The average value calculator (112A) calculates the average value of the current within the period specified by the monitor period setting signal from the filtered current waveform signal. The average value calculator (112A) calculates the average value of the current as the average value of the current, specifically the average value (I) of the current in the monitor period (MP1) within each period (P1). A11 ) is calculated. When a third mode is specified, the average value calculator (112A) calculates the average value of the current (I) for each monitor period (MP2) as the average value of the current. A12 It is also possible to obtain more ). In addition, one average value calculator (112A) may be configured, for example, as an FPGA (Field Programmable Gate Array).

[0075] The moving average value calculator (116A) is a plurality of already obtained average values ​​(I A11 The average value (I) obtained from the current of the high-frequency power (RF1) during the closest and predetermined number of monitor periods (MP1) among ) A11 The moving average value of ) (I MA11Calculate the moving average value (I MA11 ) is output to the impedance calculator (118A).

[0076] In the third mode, the moving average value calculator (116A) has a plurality of already obtained average values ​​(I A12 The average value (I) obtained from the current of the high-frequency power (RF1) during the closest and predetermined number of monitor periods (MP2) among ) A12 The moving average value of ) (I MA12 You may calculate more ). Moving average value (I MA12 ) is output to the impedance calculator (118A).

[0077] The impedance calculator (118A) is a moving average value (I MA11 ) and moving average value (V MA11 From ), the moving average value (Z) of the load impedance of the high-frequency power supply (36) MA11 Calculate the moving average value (Z MA11 ) is a measured value of the load impedance of the high-frequency power supply (36) during the monitor period (MP1). In the third mode, the impedance calculator (118A) is the moving average value (I MA12 ) and moving average value (V MA12 From ), the moving average value (Z) of the load impedance of the high-frequency power supply (36) MA12 You may calculate more ). Moving average value (Z MA12 ) is the measured value of the load impedance of the high-frequency power supply (36) during the monitoring period (MP2).

[0078] The controller (40c) controls the matching circuit (40a) to set the load impedance of the high-frequency power supply (36). In one embodiment, the controller (40c) sets the load impedance of the high-frequency power supply (36) by adjusting the reactance of each of the variable reactance element (40g) and the variable reactance element (40h) through the actuator (40d) and the actuator (40e).

[0079] The controller (40c) has, in each of the first and second modes, a moving average value (Z MA11 The load impedance of the high-frequency power supply (36) during the period (P1) specified by ) is adjusted to a target impedance different from the output impedance of the high-frequency power supply (36).

[0080] In one embodiment, the controller (40c) can determine the target impedance from the set target value of the absolute value (|Γ1|) of the reflection coefficient (Γ1) of the high-frequency power (RF1) during the period (P1). The set target value of the absolute value (|Γ1|) during the period (P1) may be a value greater than 0. For example, the set target value of the absolute value (|Γ1|) during the period (P1) is 0.3 or greater and 0.5 or less. The reflection coefficient (Γ1) is defined by the following equation (1).

[0081] Γ1=(Z1-Z 01 ) / (Z1+Z 01 )… (1)

[0082] (1) In equation, Z 01 Ω is the characteristic impedance of the power supply line (43), and is generally 50 Ω. In equation (1), Z1 is the target impedance. Based on equation (1), the controller (40c) determines the target impedance (Z1) corresponding to the set target value of the absolute value (|Γ1|) during the period (P1). The controller (40c) determines the moving average value (Z MA11 The load impedance of the high-frequency power source (36) is set so that the load impedance of the high-frequency power source (36) in the period (P1) specified by ) is brought close to or matched to the target impedance (Z1).

[0083] When the third mode is specified, the controller (40c) may 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 the period (P1). The load impedance of the high-frequency power supply (36) is a moving average value (Z MA11 ) and moving average value (Z MA12It can be specified by the average value of ). Alternatively, the controller (40c) may adjust the load impedance of the high-frequency power supply (36) in the third mode, just as in the first and second modes, to a target impedance different from the output impedance of the high-frequency power supply (36).

[0084] As described above, the matching device (40) can stepwise change the load impedance of the high-frequency power supply (36) so that, in each of the first and second modes, the absolute value (|Γ1|) of the reflection coefficient (Γ1) is stepwise changed to a 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 supply (36) through a plurality of sub-periods (SP) within the period (P2). A plurality of sub-periods (SP) (i.e., SP1, SP2, ····, SP N The time length of each ) is TL.

[0085] Multiple period (SP1, SP2, ····, SP N The target values ​​of the absolute value (|Γ1|) of the reflection coefficient (Γ1) of the high-frequency power (RF1) in ) are different. 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 a 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. Furthermore, in FIGS. 8 and 9, ΔΓ1 is represented as ΔΓ. As shown in FIG. 8, when the subsequent period (PB) is period (P2), the sub-period [SP (N+1) The target value of the absolute value (|Γ1|) of the reflection coefficient (Γ1) in ], that is, the set target value, is zero. As shown in FIG. 9, when the subsequent period (PB) is period (P1), the sub-period [SP (N+1)The target value of the absolute value (|Γ1|) of the reflection coefficient (Γ1) in ], i.e., the set target value, is greater than zero and, for example, 0.3 or greater and 0.5 or less. In one embodiment, TL may be set to 0.5 seconds or more, and ΔΓ1 may be set to 0.2 or less. Alternatively, TL may be set to 0.2 seconds or more, and ΔΓ1 may be set to 0.1 or less. Alternatively, TL may be set to 0.5 seconds or more, and ΔΓ1 may be set to 0.05 or less.

[0086] The controller (40c) sets the load impedance of the high-frequency power supply (36). Specifically, the controller (40c) sets the load impedance of the sub-terminal (SP i In ), the load impedance of the high-frequency power supply (36) is the sub-period (SP i The target impedance (Z1) is adjusted based on equation (1) from the target value of the absolute value (|Γ1|) of the reflection coefficient (Γ1) of the high-frequency power (RF1) in ). In addition, the controller (40c) is adjusted to the target impedance (Z1) specified based on equation (1) from the target value of the reflection coefficient (Γ1). Furthermore, the controller (40c) is a sub-terminal (SP i The load impedance of the high-frequency power supply (36) in the above can be determined from the measured value of the load impedance of the high-frequency power supply (36) obtained from the sensor (40b). The sensor (40b) can obtain the measured value of the load impedance of the high-frequency power supply (36) from the aforementioned filtered voltage waveform signal and filtered current waveform signal.

[0087] When a third mode is specified, the controller (40c) may 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 the period (P2). In the third mode, just as in the first and second modes, the controller (40c) may also change the load impedance of the high-frequency power supply (36) in stages during the period (P2) up to the target impedance for the subsequent period (PB).

[0088] As shown in FIG. 6, in one embodiment, the high-frequency power supply (38) has an oscillator (38a), a power amplifier (38b), a power sensor (38c), and a power control unit (38e). The power control unit (38e) is composed of a processor called a CPU. The power control unit (38e) controls the oscillator (38a), the power amplifier (38b), and the power sensor (38c) by applying a control signal to each of the oscillator (38a), the power amplifier (38b), and the power sensor (38c). The power control unit (38e) generates a control signal applied to each of the oscillator (38a), the power amplifier (38b), and the power sensor (38c) using a signal applied from the main control unit (70) and a signal applied from the power sensor (38c).

[0089] The signal provided from the main control unit (70) to the power control unit (38e) includes a second frequency setting signal and the aforementioned mode setting signal. The second frequency setting signal is a signal that specifies the setting frequency of the high frequency power (RF2). When the first mode or the third mode is specified, the signal provided from the main control unit (70) to the power control unit (38e) further includes a second modulation setting signal. The second modulation setting signal is a signal that specifies the modulation frequency and duty ratio of the modulation wave (MW2). Additionally, 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). Furthermore, in the first mode, the modulation frequency of the modulation wave (MW1) and the modulation frequency of the modulation wave (MW2) may be the same. When a second mode is specified, the signal given from the main control unit (70) to the power control unit (38e) further includes a second power level setting signal that specifies the power of the continuous wave (CW2).

[0090] The power control unit (38e) is a set frequency [e.g., basic frequency (f)] specified by the second frequency setting signal. B2The oscillator (38a) is controlled to output a high-frequency signal having )]. The output of the oscillator (38a) is connected to the input of the power amplifier (38b). The power amplifier (38b) generates high-frequency power (RF2) by amplifying the high-frequency signal output from the oscillator (38a). The power amplifier (38b) is controlled by the power control unit (38e).

[0091] When the first mode or the third mode is specified, the power control unit (38e) controls the power amplifier (38b) to generate a modulated wave (MW2) from a high-frequency signal according to the second modulation setting signal during the period (P1). When the first mode or the third mode is specified, the power control unit (38e) controls the power amplifier (38b) to generate a continuous wave (CW2) from a high-frequency signal according to the second power level setting signal during the period (P2). Additionally, when the second mode is specified, the power control unit (38e) controls the power amplifier (38b) to generate a continuous wave (CW2) from a high-frequency signal according to the second power level setting signal during the periods (P1) and (P2).

[0092] A power sensor (38c) is provided at the rear end of the power amplifier (38b). The power sensor (38c) has a directional coupler, a traveling wave detector, and a reflected wave detector. The directional coupler provides a portion of the traveling wave of the high-frequency power (RF2) to the traveling wave detector and provides the reflected wave to the reflected wave detector. A second frequency-specific signal, which specifies the set frequency of the high-frequency power (RF2), is provided to the power sensor (38c) from the power control unit (38e). The traveling wave detector is a measured value of the power level of a component having the same frequency as the set frequency specified by the second frequency-specific signal among the total frequency components of the traveling wave, i.e., a measured value of the power level of the traveling wave (P f21 Generates ). Measurement value (P f21 ) is assigned to the power control unit (38e).

[0093] The second frequency-specific signal is also applied to the reflected wave detector from the power control unit (38e). The reflected wave detector is a measured value of the power level of a component having the same frequency as the set frequency specified by the second frequency-specific signal among the total frequency components of the reflected wave, i.e., a measured value of the power level of the reflected wave (P r21 Generates ). Measurement value (P r21 ) is assigned to the power control unit (38e). In addition, the reflected wave detector is a measured value of the total power level of the entire frequency component of the reflected wave, i.e., a measured value of the power level of the reflected wave (P r22 Generates ). Measurement value (P r22 ) is provided to the power control unit (38e) for protection of the power amplifier (38b).

[0094] In one embodiment, the high-frequency power supply (38) may perform load power control during the period (P1). That is, the high-frequency power supply (38) may adjust the power level of the high-frequency power (RF2) so that the load power level of the high-frequency power (RF2) during the period (P1) approaches or matches a specified target power level. The power control unit (38e) may control the power amplifier (38b) in the load power control of the high-frequency power supply (38).

[0095] In load power control when a first mode or a third mode is specified, the power control unit (38e) can control the power amplifier (38b) to adjust the power level of the modulation wave (MW2) in the first sub-period (SP11). The power level of the modulation wave (MW2) in the first sub-period (SP11) is the load power level (P11) in the monitor period (MP1). L21 ) is adjusted to approach or match the specified target power level.

[0096] As described above, the monitor period (MP1) is a period within the first sub-period (SP11). The monitor period (MP1) may be a period that begins after a predetermined length of time has elapsed from the start of the first sub-period (SP11). The monitor period (MP1) is specified by the main control unit (70). Load power level (P L21 ) is the difference between the power level of the traveling wave of the high-frequency power (RF2) during the monitor period (MP1) and the power level of the reflected wave of the high-frequency power (RF2) during the monitor period (MP1). Load power level (P L21 ) is the measured value (P) during the monitor period (MP1). f21 ) and measured value (P r21 It is obtained as the difference of ). Load power level (P L21 ) is the measured value (P) during the monitor period (MP1). f21 The average value and measured value (P r21 It may be calculated as the difference in the average values ​​of ). Or, load power level (P L21 ) is a measured value (P) during multiple monitor periods (MP1). f21 The moving average of ) and the measured value (P r21 It may be calculated as the difference of the moving average values ​​of ).

[0097] If the power level of the modulated wave (MW2) in the second sub-period (SP12) is not 0[W], the high-frequency power supply (38) may perform load power control of the modulated wave (MW2) in the second sub-period (SP12). In this load power control, the power control unit (38e) may 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) is the load power level (P) in the monitor period (MP2). L22 ) is adjusted to approach or match the specified target power level.

[0098] As described above, the monitor period (MP2) may be a period that coincides with the second sub-period (SP12). Alternatively, the monitor period (MP2) may be a period within the second sub-period (SP12) and may be a period that begins after a predetermined length of time has elapsed from the start of the second sub-period (SP12). The monitor period (MP2) is specified by the main control unit (70). Load power level (P L22 ) is the difference between the power level of the traveling wave of the high-frequency power (RF2) during the monitor period (MP2) and the power level of the reflected wave of the high-frequency power (RF2) during the monitor period (MP2). The load power level (PL22) is the measured value (P) during the monitor period (MP2). f21 ) and measured value (P r21 It is obtained as the difference of ). Load power level (P L22 ) is the measured value (P) during the monitor period (MP2). f21 The average value and measured value (P r21 It may also be calculated as the difference of the average values ​​of ). In addition, the load power level (P L22 ) is a measured value (P) during multiple monitor periods (MP2). f21 The moving average of ) and the measured value (P r21 It may be calculated as the difference of the moving average values ​​of ).

[0099] Even when the second mode is specified, the high-frequency power supply (38) may perform load power control. In load power control when the second mode is specified, the power control unit (38e) may control the power amplifier (38b) to adjust the power level of the continuous wave (CW2) during the period (P1). The power level of the continuous wave (CW2) during the period (P1) is the load power level (P1) during the monitor period (MP1). L21 Load power level (P) during ) and monitor period (MP2) L22 The average value of ) is adjusted to match or approach a specified target power level.

[0100] The matching device (42) is configured to set the load impedance of the high-frequency power supply (38), i.e., the load impedance. In each of the first and third modes, the matching device (42) may set the load impedance of the high-frequency power supply (38) during the period (P1) to a target impedance different from the output impedance of the high-frequency power supply (38). The load impedance of the high-frequency power supply (38) during the period (P1) may be determined by the measured value of the load impedance of the high-frequency power supply (38) during the monitoring period (MP1).

[0101] In the second mode, the matching device (42) may match the load impedance of the high-frequency power supply (38) during the period (P1) to the output impedance of the high-frequency power supply (38). Alternatively, the matching device (42) may, in the second mode as in the first and third modes, set the load impedance of the high-frequency power supply (38) during the period (P1) to a target impedance different from the output impedance of the high-frequency power supply (38).

[0102] The matching device (42) changes the load impedance of the high-frequency power source (38) in stages during the period (P2) in each of the first mode and the third mode to the target impedance for the subsequent period (PB). That is, the matching device (42) is configured to change the load impedance of the high-frequency power source (38) in stages during the period (P2) before or after the power generated by the high-frequency power source (38) is switched from the power wave (W21) to the power wave (W22) to the target impedance for the subsequent period (PB).

[0103] The matching device (42) changes the load impedance of the high-frequency power supply (38) in stages so that, in each of the first and third modes, as shown in FIG. 8 and FIG. 9, the absolute value (|Γ2|) of the reflection coefficient (Γ2) in the period (P2) is changed in stages to a set target value for the subsequent period (PB). As shown in FIG. 8, when the subsequent period (PB) in each of the first and third modes is the period (P2), the set target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) for the subsequent period (PB) may be zero. As shown in FIG. 9, when the subsequent period (PB) in each of the first and third modes is the period (P1), the set target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) for the subsequent period (PB) is greater than zero and, for example, 0.3 or greater and 0.5 or less.

[0104] As previously mentioned, the subsequent period (PB) includes a plurality of consecutive period (SP). As previously mentioned, the plurality of period (SP) includes period (SP1, SP2, ..., SP N ...includes ). The matching device (42) includes sub-periods (SP1, SP2, ..., SP2) in the period (P2). N The load impedance of the high-frequency power supply (38) can be changed stepwise so that the absolute value (|Γ2|) of the reflection coefficient (Γ2) is changed stepwise to a target value for the subsequent period (PB). As shown in FIG. 8, when the subsequent period (PB) is period (P2), the matching device (42) [after the start of the subsequent period (PB)], the sub-periods (SP1, SP2, ····, SP1) within period (P2) N The load impedance of the high-frequency power supply (38) is changed stepwise through ). As shown in FIG. 9, when the subsequent period (PB) is period (P1), the matching device (42) has a sub-period (SP1, SP2, ····, SP2) within the period (P2) prior to the start of the subsequent period (PB) [period (P1)]. NThe load impedance of the high-frequency power supply (38) is changed stepwise through ). The matching unit (42) is, between [SP (N+1) The load impedance of the high-frequency power supply (38) is set so that the absolute value (|Γ2|) of the reflection coefficient (Γ2) in ] is set as the target value for the subsequent period (PB).

[0105] In the second mode, the matching device (42) may match the load impedance of the high-frequency power supply (38) during the period (P2) to the output impedance of the high-frequency power supply (38). Alternatively, the matching device (42) may, in the second mode as in the first and third modes, gradually change the load impedance of the high-frequency power supply (38) during the period (P2) to the target impedance for the subsequent period (PB).

[0106] In one embodiment, the matching device (42) has a matching circuit (42a), a sensor (42b), a controller (42c), an actuator (42d), and an actuator (42e), as shown in FIG. 6. The matching circuit (42a) may include a variable reactance element (42g) and a variable reactance element (42h). Each of the variable reactance element (42g) and the variable reactance element (42h) is, for example, a variable capacitor. Additionally, the matching circuit (42a) may further include an inductor, etc.

[0107] 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) according to the measured value of the load side impedance (i.e., load impedance) of the high-frequency power supply (38) provided by the sensor (42b). The controller (42c) adjusts the load impedance of the high-frequency power supply (38) by controlling the actuator (42d) and the actuator (42e) to adjust the reactance of each of the variable reactance element (42g) and the variable reactance element (42h). The actuator (42d) and the actuator (42e) are, for example, motors.

[0108] The sensor (42b) is configured to acquire a measured value of the load impedance of the high-frequency power supply (38). In one embodiment, the measured value of the load impedance of the high-frequency power supply (38) is acquired as a moving average value. As shown in FIG. 7, the sensor (42b) may have a current detector (102B), a voltage detector (104B), filters (106B and 108B), an average value calculator (110B and 112B), a moving average value calculator (114B and 116B), and an impedance calculator (118B).

[0109] The voltage detector (104B) detects the voltage waveform of the high-frequency power (RF2) transmitted over the power supply line (45) and outputs a voltage waveform analog signal representing the voltage waveform. This voltage waveform analog signal is input to a 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 specific signal from the power control unit (38e) and generates a filtered voltage waveform signal by extracting only the frequency component corresponding to the frequency specified by the second frequency specific signal from the voltage waveform digital signal. The filter (106B) may be configured as an FPGA (Field Programmable Gate Array).

[0110] 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 monitor period setting signal from the main control unit (70). The average value calculator (110B) calculates the average value of the voltage within the period specified by the monitor period setting signal from the filtered voltage waveform signal. The average value calculator (110B) calculates the average value of the voltage as the average value of the voltage, specifically the average value of the voltage (V) during the monitor period (MP1). B11 ) is calculated. When the second mode is specified, the average value calculator (110B) calculates the average value of the voltage during the monitor period (MP2) as the average value of the voltage (VB12 It is also possible to obtain more ). In addition, the average value calculator (110B) may be configured, for example, as an FPGA (Field Programmable Gate Array).

[0111] The moving average value calculator (114B) is a plurality of already obtained average values ​​(V B11 The average value (V) obtained from the voltage of the high-frequency power (RF2) during the closest and predetermined number of monitor periods (MP1) among ) B11 The moving average value of ) (V MB11 Calculate the moving average value (V MB11 ) is output to the impedance calculator (118B).

[0112] In the second mode, the moving average value calculator (114B) has a plurality of already obtained average values ​​(V B12 The average value (V) obtained from the voltage of the high-frequency power (RF2) during the closest and predetermined number of monitor periods (MP2) among ) B12 The moving average value of ) (V MB12 You may calculate more ). Moving average value (V MB12 ) is output to the impedance calculator (118B).

[0113] The current detector (102B) detects the current waveform of the high-frequency power (RF2) transmitted over the power supply line (45) and outputs a current waveform analog signal representing the current waveform. This current waveform analog signal is input to a filter (108B). The filter (108B) generates a current waveform digital signal by digitizing the input current waveform analog signal. The filter (108B) receives the second frequency specification signal from the power control unit (38e) and generates a filtered current waveform signal by extracting only the frequency component corresponding to the frequency specified by the second frequency specification signal from the current waveform digital signal. The filter (108B) may be configured, for example, as an FPGA (Field Programmable Gate Array).

[0114] 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 monitor period setting signal from the main control unit (70). The average value calculator (112B) calculates the average value of the current within the period specified by the monitor period setting signal from the filtered current waveform signal. The average value calculator (112B) calculates the average value of the current as the average value of the current, specifically the average value (I) of the current during the monitor period (MP1) within each period (P1). B11 ) is calculated. When the second mode is specified, the average value calculator (112B) calculates the average value of the current (I) for each monitor period (MP2) as the average value of the current. B12 It is also possible to obtain more ). In addition, the average value calculator (112B) may be configured, for example, as an FPGA (Field Programmable Gate Array).

[0115] The moving average value calculator (116B) is a plurality of already obtained average values ​​(I B11 The average value (I) obtained from the current of the high-frequency power (RF2) during the closest and predetermined number of monitor periods (MP1) among ) B11 The moving average value of ) (I MB11 Calculate the moving average value (I MB11 ) is output to the impedance calculator (118B).

[0116] In the second mode, the moving average value calculator (116B) has a plurality of already obtained average values ​​(I B12 The average value (I) obtained from the current of the high-frequency power (RF2) during the closest and predetermined number of monitor periods (MP2) among ) B12 The moving average value of ) (I MB12 You may calculate more ). Moving average value (I MB12 ) is output to the impedance calculator (118B).

[0117] The impedance calculator (118B) is a moving average value (I MB11 ) and moving average value (VMB11 From ), the moving average value (Z) of the load impedance of the high-frequency power supply (38) MB11 Calculate the moving average value (Z MB11 ) is a measured value of the load impedance of the high-frequency power supply (38) during the monitor period (MP1). In the second mode, the impedance calculator (118B) is a moving average value (I MB12 ) and moving average value (V MB12 From ), the moving average value (Z) of the load impedance of the high-frequency power supply (38) MB12 You may calculate more ). Moving average value (Z MB12 ) is the measured value of the load impedance of the high-frequency power supply (38) during the monitoring period (MP2).

[0118] The controller (42c) controls the matching circuit (42a) to set the load impedance of the high-frequency power supply (38). In one embodiment, the controller (42c) sets the load impedance of the high-frequency power supply (38) by adjusting the reactance of each of the variable reactance element (42g) and the variable reactance element (42h) through the actuator (42d) and the actuator (42e).

[0119] The controller (42c) has, in each of the first and third modes, a moving average value (Z MB11 The load impedance of the high-frequency power supply (38) during the period (P1) specified by ) is adjusted to a target impedance different from the output impedance of the high-frequency power supply (38).

[0120] In one embodiment, the controller (42c) can determine the target impedance from the set target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) of the high-frequency power (RF2) during the period (P1). The set target value of the absolute value (|Γ2|) during the period (P1) may be a value greater than 0. For example, the set target value of the absolute value (|Γ2|) during the period (P1) is 0.3 or greater and 0.5 or less. The reflection coefficient (Γ2) is defined by the following equation (2).

[0121] Γ2=(Z2-Z 02 ) / (Z2+Z 02 )… (2)

[0122] (2) In equation, Z 02 Ω is the characteristic impedance of the power supply line (45), and is generally 50 Ω. In equation (2), Z2 is the target impedance. Based on equation (2), the controller (42c) determines the target impedance (Z2) corresponding to the set target value of the absolute value (|Γ2|) during the period (P1). The controller (42c) determines the moving average value (Z MB11 The load impedance of the high-frequency power source (38) is set so that the load impedance of the high-frequency power source (38) in the period (P1) specified by ) approaches or matches the target impedance (Z2).

[0123] When the second mode is specified, the controller (42c) may match the load impedance of the high-frequency power supply (38) to the output impedance (matching point) of the high-frequency power supply (38) during the period (P1). The load impedance of the high-frequency power supply (38) is a moving average value (Z MB11 ) and moving average value (Z MB12 It can be specified by the average value of ). Alternatively, the controller (42c) may adjust the load impedance of the high-frequency power supply (38) in the second mode, just as in the first and third modes, to a target impedance different from the output impedance of the high-frequency power supply (38).

[0124] As described above, the matching unit (42) can change the load impedance of the high-frequency power supply (38) in stages so that, in each of the first and third modes, the absolute value (|Γ2|) of the reflection coefficient (Γ2) is changed in stages to a set target value for the subsequent period (PB). As described above, the matching unit (42) changes the load impedance of the high-frequency power supply (38) in stages through a plurality of sub-periods (SP) within the period (P2).

[0125] Multiple period (SP1, SP2, ····, SP N The target values ​​of the absolute value (|Γ2|) of the reflection coefficient (Γ2) of the high-frequency power (RF2) in ) are different. The difference between the target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) in one of any two consecutive sub-periods included in a plurality of sub-periods (SP2) and the target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) in the other period is ΔΓ2. Furthermore, in FIGS. 8 and 9, ΔΓ2 is represented as ΔΓ. As shown in FIG. 8, when the subsequent period (PB) is period (P2), the sub-period [SP (N+1) The target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) in ], that is, the set target value, is zero. As shown in FIG. 9, when the subsequent period (PB) is period (P1), the sub-period [SP (N+1) The target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) in ], i.e., the set target value, is greater than zero and, for example, 0.3 or greater and 0.5 or less. In one embodiment, TL may be set to 0.5 seconds or more, and ΔΓ2 may be set to 0.2 or less. Alternatively, TL may be set to 0.2 seconds or more, and ΔΓ2 may be set to 0.1 or less. Alternatively, TL may be set to 0.5 seconds or more, and ΔΓ2 may be set to 0.05 or less.

[0126] The controller (42c) sets the load impedance of the high-frequency power supply (38). Specifically, the controller (42c) sets the load impedance of the sub-terminal (SP i In ), the load impedance of the high-frequency power supply (38) is the sub-period (SP i The target impedance (Z2) is adjusted based on equation (2) from the target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) of the high-frequency power (RF2) in ). In addition, the controller (42c) is adjusted to the target impedance (Z2) specified from the target value of the absolute value (|Γ2|) of the reflection coefficient (Γ2) of the high-frequency power (RF2) in ). Also, the controller (42c) is, the sub-period (SP iThe load impedance of the high-frequency power supply (38) in the above can be determined from the measured value of the load impedance of the high-frequency power supply (38) obtained from the sensor (42b). The sensor (42b) can obtain the measured value of the load impedance of the high-frequency power supply (38) from the aforementioned filtered voltage waveform signal and filtered current waveform signal.

[0127] When the second mode is specified, the controller (42c) may match the load impedance of the high-frequency power supply (38) to the output impedance (matching point) of the high-frequency power supply (38) during the period (P2). In the second mode, just as in the first and third modes, the controller (42c) may also change the load impedance of the high-frequency power supply (38) in stages during the period (P2) up to the target impedance for the subsequent period (PB).

[0128] In the plasma processing device (1), the matching device (40) gradually changes the load impedance to a target impedance for a subsequent period during the period when a continuous wave (CW1) is supplied before or after the power supplied from the high-frequency power source (36) is switched from a power wave (W11) to a power wave (W12). Accordingly, the matching device (40) is able to follow the change in load impedance that must be set after the power from the high-frequency power source (36) is switched from a power wave (W11) to a power wave (W12). Accordingly, it is possible to reduce reflection after the power supplied from the high-frequency power source (36) is switched from a power wave (W11) to a power wave (W12). Additionally, the matching device (42) gradually changes the load impedance to a target impedance for a subsequent period during the period when a continuous wave (CW2) is supplied before or after the power supplied from the high-frequency power source (38) is converted from a power wave (W21) to a power wave (W22). Accordingly, the matching device (42) is able to follow the change in load impedance that must be set after the power from the high-frequency power source (38) is converted from a power wave (W21) to a power wave (W22). Accordingly, it is possible to reduce reflection after the power supplied from the high-frequency power source (38) is converted from a power wave (W21) to a power wave (W22).

[0129] In one embodiment, the matching unit (40) adjusts the load impedance of the high-frequency power supply (36) during the period (P1) to a target impedance different from the output impedance of the high-frequency power supply (36). According to this embodiment, reflection from the load for the modulation wave (MW1) during the period (P1) can be reduced. In one embodiment, in each of the first and third modes, the matching unit (42) adjusts the load impedance of the high-frequency power supply (38) during the period (P1) to a target impedance different from the output impedance of the high-frequency power supply (38). According to this embodiment, reflection from the load for the modulation wave (MW2) during the period (P1) can be reduced.

[0130] In one embodiment, load power control of the modulation wave (MW1) can be performed during the period (P1). According to this embodiment, even if reflection occurs during the period (P1) due to the target impedance being different from the output impedance of the high-frequency power source (36), the modulation wave (MW1) of the target power level can be coupled to the plasma. In one embodiment, load power control of the modulation wave (MW2) can be performed during the period (P1). According to this embodiment, even if reflection occurs during the period (P1) due to the target impedance being different from the output impedance of the high-frequency power source (38), the modulation wave (MW2) of the target power level can be coupled to the plasma.

[0131] Refer to FIG. 10 below. FIG. 10 is a flowchart of a matching method according to one exemplary embodiment. In the matching method shown in FIG. 10 (hereinafter referred to as "method (MT)"), power supplied from at least one of a high-frequency power source (36) and a high-frequency power source (38) is converted from a power wave of one type, such as a continuous wave or a modulated wave, to a power wave of the other type. That is, in the method (MT), a power wave (W11) is supplied from the high-frequency power source (36), and a power wave (W21) is supplied from the high-frequency power source (38). Subsequently, at least one of a power wave (W12) from the high-frequency power source (36) or a power wave (W22) from the high-frequency power source (38) is supplied. The power wave (W11) may be supplied from the high-frequency power source (36) over two consecutive periods, or the power wave (W21) may be supplied from the high-frequency power source (36) over two consecutive periods. In the method (MT), the power supplied from at least one of the high-frequency power source (36) and the high-frequency power source (38) may be alternately switched from one power wave of the continuous wave and the modulated wave to the other power wave.

[0132] The method (MT) begins with process ST1. In process ST1, a power wave (W11) is supplied from a high-frequency power source (36), and a power wave (W21) is supplied from a high-frequency power source (38). During the execution of process ST1, the load impedance of the high-frequency power source (36) is set by a matching device (40). If the power wave (W11) is a modulated wave (MW1), during the execution of process ST1, the load impedance of the high-frequency power source (36) may be adjusted to a target impedance different from the output impedance of the high-frequency power source (36), as described above. Additionally, if the power wave (W11) is a modulated wave (MW1), load power control may be performed by the high-frequency power source (36), as described above.

[0133] When the power wave (W11) is a continuous wave (CW1), the load impedance of the high-frequency power supply (36) may be matched to the output impedance of the high-frequency power supply (36) during the execution of process ST1. Alternatively, even when the power wave (W11) is a continuous wave (CW1), the load impedance of the high-frequency power supply (36) may be adjusted to a target impedance different from the output impedance of the high-frequency power supply (36) during the execution of process ST1, just as when the power wave (W11) is a modulated wave (MW1).

[0134] During the execution of process ST1, the load impedance of the high-frequency power supply (38) is set by the matching device (42). When the power wave (W21) is a modulated wave (MW2), during the execution of process ST1, the load impedance of the high-frequency power supply (38) may be adjusted to a target impedance different from the output impedance of the high-frequency power supply (38), as described above. Additionally, when the power wave (W21) is a modulated wave (MW2), load power control may be performed by the high-frequency power supply (38) as described above during the execution of process ST1.

[0135] When the power wave (W21) is a continuous wave (CW2), the load impedance of the high-frequency power supply (38) may be matched to the output impedance of the high-frequency power supply (38) during the execution of process ST1. Alternatively, even when the power wave (W21) is a continuous wave (CW2), the load impedance of the high-frequency power supply (38) may be adjusted to a target impedance different from the output impedance of the high-frequency power supply (36) during the execution of process ST1, just as when the power wave (W21) is a modulated wave (MW2).

[0136] In process STJa, it is determined whether the power wave supplied during the preceding period (PA) among two consecutive periods is a continuous wave. If the continuous wave (CW1) is not supplied during the preceding period (PA), that is, if the modulated wave (MW1) is supplied, process STA2 is executed during the subsequent period (PB) among two consecutive periods. If the modulated wave (MW1) is supplied during the preceding period (PA) and the continuous wave (CW1) is supplied during the subsequent period (PB), process STA3 is executed during the subsequent period (PB). On the other hand, if the continuous wave (CW1) is supplied during the preceding period (PA), process STB3 is executed during the subsequent period (PB). If the continuous wave (CW1) is supplied during the preceding period (PA) and the modulated wave (MW1) is supplied during the subsequent period (PB), process STB2 is executed during the preceding period (PA).

[0137] In addition, if the continuous wave (CW2) is not supplied during the preceding period (PA), that is, if the modulated wave (MW2) is supplied, process STA2 is executed during the subsequent period (PB). If the modulated wave (MW2) is supplied during the preceding period (PA) and the continuous wave (CW2) is supplied during the subsequent period (PB), process STA3 is executed during the subsequent period (PB). If the continuous wave (CW2) is supplied during the preceding period (PA), process STB3 is executed during the subsequent period (PB). If the continuous wave (CW2) is supplied during the preceding period (PA) and the modulated wave (MW2) is supplied during the subsequent period (PB), process STB2 is executed during the preceding period (PA).

[0138] Process STA2 is executed when a modulated wave (MW1) is supplied during the preceding period (PA). In process STA2, a power wave for the subsequent period (PB) is supplied from the high-frequency power source (36). In process STA2, if the power wave supplied from the high-frequency power source (36) is a continuous wave (CW1), the load impedance of the high-frequency power source (36) is changed stepwise in process STA3 after the start of the subsequent period (PB) to the target impedance for the subsequent period (PB) as described above. In process STA2, if the power wave supplied from the high-frequency power source (36) is a modulated wave (MW1), the load impedance of the high-frequency power source (36) can be set to a target impedance different from the output impedance of the high-frequency power source (36).

[0139] Additionally, process STA2 is executed when a modulated wave (MW2) is supplied during the preceding period (PA). In process STA2, the power wave of the subsequent period (PB) is supplied from the high-frequency power source (38). In process STA2, if the power wave supplied from the high-frequency power source (38) is a continuous wave (CW2), the load impedance of the high-frequency power source (38) is changed stepwise in process STA3 after the start of the subsequent period (PB) to the target impedance for the subsequent period (PB) as described above. In process STA2, if the power wave supplied from the high-frequency power source (38) is a modulated wave (MW2), the load impedance of the high-frequency power source (38) can be set to a target impedance different from the output impedance of the high-frequency power source (38).

[0140] Process STB3 is executed in the subsequent period (PB) when a continuous wave (CW1) is supplied during the preceding period (PA). In Process STB3, the power wave of the subsequent period (PB) is supplied from the high-frequency power source (36). In Process STB3, if the power wave supplied from the high-frequency power source (36) is a modulated wave (MW1), Process STB2 is executed in the preceding period (PA) before the start of the subsequent period (PB). In Process STB2, the load impedance of the high-frequency power source (36) is changed stepwise up to the target impedance for the subsequent period (PB) as described above. In Process STB3, if the power wave supplied from the high-frequency power source (36) is a 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).

[0141] Process STB3 is executed in the subsequent period (PB) when a continuous wave (CW2) is supplied during the preceding period (PA). In Process STB3, the power wave of the subsequent period (PB) is supplied from the high-frequency power source (38). In Process STB3, if the power wave supplied from the high-frequency power source (38) is a modulated wave (MW2), Process STB2 is executed in the preceding period (PA) before the start of the subsequent period (PB). In Process STB2, the load impedance of the high-frequency power source (38) is changed stepwise up to the target impedance for the subsequent period (PB) as described above. In Process STB3, if the power wave supplied from the high-frequency power source (38) is a 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).

[0142] In process STJb, it is determined whether the termination condition is satisfied. The termination condition is satisfied when the number of executions of the cycle (CY) shown in FIG. 10 reaches a predetermined number. If the termination condition is not satisfied, the cycle (CY) is repeated from process STJa. If the termination condition is satisfied, the method (MT) terminates.

[0143] Although various exemplary embodiments have been described above, various additions, omissions, substitutions, and changes may be made without being limited to the aforementioned exemplary embodiments. In addition, it is possible to form other embodiments by combining elements from other embodiments.

[0144] For example, the plasma processing device (1) was a capacitively coupled plasma processing device, but the concept of the present disclosure can be applied to any plasma processing device configured to supply modulated high-frequency power from a high-frequency power source to an electrode. Examples of such plasma processing devices include, for instance, an inductively coupled plasma processing device, an electron cyclotron resonance (ECR) plasma processing device, and a plasma processing device that uses surface waves called microwaves to generate plasma.

[0145] Additionally, the plasma processing device (1) is shown to use both high-frequency power (RF1) and high-frequency power (RF2) for plasma processing, but for plasma processing, only one of the high-frequency power (RF1) and high-frequency power (RF2) may be used.

[0146] The following describes an experiment conducted using a plasma processing device (1). In the experiment, plasma was generated in the third mode of the plasma processing device (1). In the experiment, two types of power were used as the power levels of the high-frequency power (RF2): 400 W and 1000 W. Additionally, in the experiment, different values ​​were set for each of the aforementioned TL and ΔΓ2. Other conditions in the experiment are as follows.

[0147] <Condition>

[0148] Frequency of high-frequency power (RF1): 60 MHz

[0149] Continuous Wave (CW1) Power: 300 W

[0150] Frequency of high-frequency power (RF2): 40.68 MHz

[0151] Power of the modulated wave (MW2) in the first period (SP11) and power of the continuous wave (CW2) in the period (P2): 400 W or 1000 W

[0152] Power of the modulation wave (MW2) in the second period (SP12): 0 W

[0153] Modulation frequency of the modulated wave (MW2): 1 kHz

[0154] Duty cycle of modulated wave (MW2): 90%

[0155] In the experiment, the VPP of the susceptor (16) according to the high-frequency power (RF2) was measured. VPP is the peak-to-peak value of the voltage of the susceptor (16) according to the high-frequency power (RF2). In the experiment, the ratio (%) of the VPP at which reflection is not substantially observed (hereinafter referred to as the "decrease rate") of the amount of VPP reduction caused by changing the power supplied to the susceptor (16) from a modulation wave (MW2) to a continuous wave (CW2) was calculated. Table 1 shows the decrease rate when the power of the modulation wave (MW2) in the first period (SP11) and the power of the continuous wave (CW2) in the period (P2) are set to 400 W. Table 2 shows the degradation rate when the power of the modulation wave (MW2) in the first period (SP11) and the power of the continuous wave (CW2) in the period (P2) are set to 1000 W.

[0156]

[0157]

[0158] As shown in Tables 1 and 2, the experimental results showed that when TL was set to 0.5 seconds or more and ΔΓ2 was set to 0.2 or less, or when TL was set to 0.2 seconds or more and ΔΓ2 was set to 0.1 or less, the degradation rate was 10% or less. Therefore, it was confirmed that reflection is effectively suppressed when TL is set to 0.5 seconds or more and ΔΓ2 is set to 0.2 or less, or when TL is set to 0.2 seconds or more and ΔΓ2 is set to 0.1 or less. In addition, when TL was set to 0.5 seconds or more and ΔΓ2 was set to 0.05 or less, the degradation rate was 0%. Therefore, it was confirmed that almost no reflection occurs when TL is set to 0.5 seconds or more and ΔΓ2 is set to 0.05 or less.

[0159] From the foregoing description, it will be understood that various embodiments of the present disclosure are described herein for illustrative purposes only, and that various modifications may be made without departing from the scope and common knowledge of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, and the actual scope and common knowledge are indicated by the appended claims. Explanation of the symbols

[0160] 1 : Plasma processing device 10: Chamber 16 : Susceptor 36: High-frequency power supply 38: High-frequency power supply 40 : Matching unit 42 : Matching unit

Claims

Claim 1 The apparatus comprises a chamber, an electrode, a high-frequency power source electrically connected to the electrode and configured to generate high-frequency power supplied to the electrode for plasma processing within the chamber, and a matching device connected between the high-frequency power source and the electrode and configured to set a load impedance, which is the impedance of the load side of the high-frequency power source; wherein the high-frequency power source is configured to supply one power wave, either a modulated wave or a continuous wave of the high-frequency power, to the electrode during a preceding period among two consecutive periods, and to supply the other power wave, either the modulated wave or the continuous wave, to the electrode during a subsequent period among two consecutive periods, wherein the continuous wave is a wave having a stable and unchanging power level, and the modulated wave is a wave in which two power levels alternately and periodically repeat, and wherein the high-frequency power source generates the modulated wave such that the power level of the high-frequency power during the first period among the alternating first and second periods is higher than the power level of the high-frequency power during the second period, and the matching device comprises the two consecutive During the period in which the continuous wave is supplied, the load impedance is changed in stages to gradually change the load impedance to a target impedance for the subsequent period, and the matching unit is configured to gradually change the load impedance to gradually change the absolute value of the reflection coefficient of the high-frequency power to a set target value for the subsequent period during the period in which the continuous wave is supplied, and the matching unit is configured to gradually change the load impedance to gradually decrease the absolute value of the reflection coefficient of the high-frequency power to zero after the power supplied to the electrode from the high-frequency power source is switched from the modulated wave to the continuous wave, and the matching unit is configured to gradually change the load impedance to gradually decrease the absolute value of the reflection coefficient of the high-frequency power to zero during the period in which the continuous wave is supplied,A plasma processing apparatus configured to gradually change the absolute value of the reflection coefficient through a plurality of consecutive sub-periods to a set target value for a subsequent period, wherein the time 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, or the time length is set to 0.2 seconds or more and the difference is set to 0.1 or less. Claim 2 delete Claim 3 delete Claim 4 A plasma processing apparatus according to claim 1, wherein the matching device is configured to change the load impedance in steps so as to increase the absolute value of the reflection coefficient of the high-frequency power in steps to a set target value greater than zero before the power supplied to the electrode from the high-frequency power source is switched from the continuous wave to the modulated wave. Claim 5 In paragraph 4, the plasma processing device wherein the set target value is 0.3 or more and 0.5 or less. Claim 6 delete Claim 7 A plasma processing apparatus according to claim 1, wherein the time length is set to 0.5 seconds or more and the difference is set to 0.05 or less. Claim 8 A plasma processing apparatus according to claim 1, wherein the matching device is configured to adjust the load impedance of the high-frequency power source, which is the load impedance of the high-frequency power source during the period in which the modulation wave is supplied during the two consecutive periods and is specified by the measured value during the monitoring period within the first period, to a target impedance different from the output impedance of the high-frequency power source. Claim 9 A plasma processing device, wherein, in paragraph 8, the monitor period is a period that begins after a predetermined length of time has elapsed from the start of the first sub-period. Claim 10 A plasma processing apparatus according to claim 8 or 9, wherein the matching device is configured to determine the target impedance from the set target value of the absolute value of the reflection coefficient of the modulation wave during the period in which the modulation wave is supplied. Claim 11 A plasma processing apparatus according to claim 10, wherein the set target value of the absolute value of the reflection coefficient is 0.3 or more and 0.5 or less. Claim 12 A plasma processing apparatus according to claim 8 or 9, wherein the high-frequency power source is configured to adjust the power level of the modulation wave so as to bring the load power level, which is the difference between the power level of the propagating wave of the modulation wave and the power level of the reflected wave of the modulation wave, closer to or match the target power level. Claim 13 A matching method performed in a plasma processing apparatus, wherein the plasma processing apparatus comprises a chamber, an electrode, a high-frequency power source electrically connected to the electrode and configured to generate high-frequency power supplied to the electrode for plasma processing within the chamber, and a matching device connected between the high-frequency power source and the electrode and configured to set a load impedance, which is the impedance of the load side of the high-frequency power source, wherein the matching method comprises, in a preceding period among two consecutive periods, a power wave of either a modulated wave or a continuous wave of the high-frequency power from the high-frequency power source to the electrode, wherein the continuous wave is a wave having a stable and unchanging power level, and the modulated wave is a wave in which two power levels alternately and periodically repeat, and wherein the modulated wave is generated such that the power level of the high-frequency power in the first period among the alternating first and second periods is higher than the power level of the high-frequency power in the second period, and wherein, in a subsequent period among the two consecutive periods, the modulated wave and the continuous wave of the high-frequency power are supplied to the electrode The method comprises a process of supplying a power wave on the other side, and a process of gradually changing the load impedance to a target impedance for a subsequent period during the period in which the continuous wave is supplied among the two consecutive periods, wherein in the process of gradually changing the load impedance, the load impedance is gradually changed so as to gradually change the absolute value of the reflection coefficient of the high-frequency power to a set target value for the subsequent period, and after the power supplied to the electrode from the high-frequency power source is switched from the modulated wave to the continuous wave, in the process of gradually changing the load impedance, the load impedance is gradually changed so as to gradually reduce the absolute value of the reflection coefficient of the high-frequency power to zero, and during the period in which the continuous wave is supplied,A matching method wherein the load impedance is changed stepwise so as to change the absolute value of the reflection coefficient stepwise through a plurality of consecutive sub-periods to a set target value for a subsequent period, wherein the time length of each of the plurality of sub-periods is set to 0.5 seconds or more, and furthermore, 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, or wherein the time length is set to 0.2 seconds or more and the difference is set to 0.1 or less. Claim 14 delete Claim 15 delete Claim 16 A matching method according to claim 13, wherein, in the process of changing the load impedance in steps before the power supplied to the electrode from the high-frequency power source is switched from the continuous wave to the modulated wave, the load impedance is changed in steps such that the absolute value of the reflection coefficient of the high-frequency power is increased in steps to the set target value greater than zero. Claim 17 In Clause 16, the above-mentioned target value is a matching method in which the setting target value is 0.3 or more and 0.5 or less. Claim 18 delete Claim 19 A matching method according to claim 13, wherein the time length is set to 0.5 seconds or more, and the difference is also set to 0.05 or less.

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