Control method and plasma processing apparatus

Abstract

The invention provides a control method and a plasma processing apparatus. A method for controlling a plasma processing apparatus having a first electrode on which an object to be processed is placed includes: supplying bias power to the first electrode; and a step of supplying a generation source power having a frequency higher than the bias power to the plasma processing space, the generation source power having a first state and a second state, the control method including a first control step, and a first control step in which the first state and the second state are alternately applied in synchronization with a phase within one cycle of a reference electrical state indicating any one of a voltage, a current, or an electromagnetic field measured by the bias power supply system.

Description

[0001] This case is a divisional application of the application entitled “Control method and plasma processing device” with an application date of June 12, 2019 and application number 201980017588.2 (international application number PCT / JP2019 / 023238). Technical Field

[0002] The invention relates to a control method and a plasma processing device. Background Art

[0003] A technology is known in which, during etching, the etching rate of the polycrystalline silicon layer is made uniform by synchronizing the on and off (ON / OFF) of the high-frequency power applied for ion attraction and the high-frequency power for plasma generation so that ions reach the polycrystalline silicon layer (for example, refer to Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-64915 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] In Patent Document 1, two high-frequency powers of different frequencies, namely, source power for plasma generation and bias power for ion attraction, are applied into a processing container to control the etching rate.

[0009] The present invention provides a technique for controlling the quantity and quality of free radicals and ions.

[0010] Technical solutions for solving technical problems

[0011] According to one embodiment of the present invention, there is provided a control method for a plasma processing device having a first electrode for carrying a processed object, the method comprising: a step of supplying bias power to the first electrode; and a step of supplying a generated source power having a frequency higher than the bias power to a plasma processing space, the generated source power having a first state and a second state, the control method comprising a first control step of alternately applying the first state and the second state in phase synchronization with a period of a reference electrical state, wherein the reference electrical state represents a signal synchronized with a period of the biased high frequency, or any one of a voltage, a current or an electromagnetic field measured by a power supply system of the bias power.

[0012] Effects of the Invention

[0013] According to one aspect, the amount and quality of free radicals and ions can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. 1 is a diagram showing an example of a plasma processing apparatus according to an embodiment.

[0015] Figure 2A It is a diagram showing an example of the configuration of a control unit according to one embodiment.

[0016] Figure 2B This is a diagram showing a case where control is performed using a phase signal of a sensor installed in a power supply system, or a case where control is performed using a signal synchronized with a high frequency cycle of bias power according to an embodiment.

[0017] Figure 3 This is a diagram showing an example of the timing of supplying HF according to the phase within one cycle of LF according to one embodiment.

[0018] Figure 4 This is a diagram showing an example of the timing of supplying HF according to the phase within one cycle of LF according to one embodiment.

[0019] Figure 5 This is a diagram showing an example of the relationship between the phase within one cycle of LF, the plasma density Ne, and the self-bias Vdc according to one embodiment.

[0020] Figure 6 This is a diagram showing an example of reflected wave power according to one embodiment.

[0021] Figure 7 This is a diagram showing an example of reflected wave power according to one embodiment.

[0022] Figure 8 It is a diagram for explaining a control method according to Modification 1 of one embodiment.

[0023] Fig. 9 It is a diagram for explaining a control method according to a second modification of an embodiment.

[0024] Fig.10 It is a diagram for explaining a control method according to a third modification of one embodiment.

[0025] Fig.11 It is a diagram for explaining a control method according to a fourth modification of an embodiment.

[0026] Fig.12 This is a diagram showing an example of IMD (intermodulation distortion) according to one embodiment.

[0027] Fig.13A It is a timing chart showing a control method according to a modification example 5-1 of one embodiment.

[0028] Fig. 13B It is a timing chart showing a control method according to a variation 5-2 of one embodiment.

[0029] Fig. 13C It is a timing chart showing a control method according to a variation 5-3 of one embodiment.

[0030] Fig.13D It is a timing chart showing a control method according to a variation 5-4 of one embodiment.

[0031] Fig.14 It is a timing chart showing a control method according to a sixth variation of an embodiment.

[0032] Fig.15A It is a timing chart showing a control method according to a variation 7-1 of one embodiment.

[0033] Fig. 15B It is a timing chart showing a control method of a variation 7-2 of an embodiment.

[0034] Fig. 15C It is a timing chart showing a control method of a variation 7-3 of an embodiment.

[0035] Fig.15D It is a timing chart showing a control method of a variation 7-4 of an embodiment.

[0036] Fig.16 This is a diagram showing an example of reflected wave power of generated source power according to one embodiment.

[0037] Fig.17 This is a timing chart for explaining a control method according to Modification 8 of one embodiment.

[0038] Fig.18 This is a timing chart for explaining a control method according to a ninth modification of an embodiment.

[0039] Fig.19 This is a timing chart for explaining a control method according to a tenth modification of an embodiment.

[0040] Fig. 20 This is a timing chart for explaining a control method according to Modification 11 of one embodiment.

[0041] Fig.21 A timing chart showing a control method according to Modification 12 of an embodiment.

[0042] Fig. 22 It is a timing chart showing a control method according to Modification 13 of one embodiment. DETAILED DESCRIPTION

[0043] Hereinafter, the mode for implementing the present invention will be described with reference to the accompanying drawings. In addition, in this specification and the accompanying drawings, the same reference numerals are attached to substantially the same structures, and repeated descriptions are omitted.

[0044] Hereinafter, the frequency (high frequency) of the generated source power is referred to as “HF” (High Frequency), and the generated source power is referred to as “HF power”. Furthermore, the frequency (high frequency) of the bias power lower than the frequency of the generated source power is referred to as “LF” (Low Frequency), and the bias power is referred to as “LF power”.

[0045] [Preface]

[0046] When two high-frequency powers of different frequencies, namely, source power for plasma generation and bias power for ion attraction, are applied into a processing chamber, IMD (Intermodulation distortion) may occur to generate reflected wave power.

[0047] IMD not only causes poor matching, but also requires a high-frequency power supply with a capacity that can output a higher high-frequency power than originally required for reflection tolerance and plasma maintenance. Therefore, in order to reduce the generation of IMD, research has been conducted on optimizing the cable length of the coaxial cable used in the power supply line of the high-frequency power supply.

[0048] However, IMD is generated as a frequency of the sum and / or difference of the fundamental wave and / or harmonics of HF power and the fundamental wave and / or harmonics of LF power. Therefore, in the method of optimizing the cable length of the coaxial cable, even if the reflected wave power of the high frequency power of a specific frequency can be reduced, the reflected wave power of other frequencies generated by the sum and / or difference of the fundamental wave and / or harmonics of HF power and LF power included in the IMD cannot be eliminated.

[0049] In addition, the lower the frequency of the LF power, the more IMD will be generated at the frequency close to the fundamental wave of the HF power, so it is considered to increase the frequency of the LF power as much as possible to suppress the generation of IMD at the frequency close to the fundamental wave of the HF power. However, in recent years, especially in the etching process of high aspect ratio, the processing results are better when the frequency of the LF power is reduced. That is, the deeper the hole with a high aspect ratio is etched, the lower the etching rate, so the frequency of the LF power is made lower and the power is increased. As a result, the etching rate can be increased in the etching of high aspect ratio. However, under this processing condition, IMD further increases, so since the LF power tends to develop towards high power and low frequency in recent years, the reflected wave power of the high frequency power has been increasing. In particular, when the LF power and the HF power are applied to the same electrode, the reflected wave power of the high frequency power increases.

[0050] For example, Fig.12 This shows an example of the reflected wave power generated when HF power of a predetermined frequency is applied to an electrode to which LF power is applied. The IMD is synchronized with the phase of the Vpp (Peak to Peak) of the LF and the intensity changes periodically. Fig.12 In the example, when the potential of LF is near the maximum positive value, IMD is approximately 0W, that is, it becomes a state where no reflection occurs. In addition, when the potential of LF is in the negative range, IMD becomes relatively low. When the potential of LF exceeds the maximum positive value and then becomes negative, the maximum reflected wave power is generated and IMD becomes maximum.

[0051] Therefore, the inventors proposed a control method for suppressing the generation of IMD according to the phase of LF in consideration of the time when IMD is generated, and a plasma processing apparatus implementing the control method. In addition, the inventors proposed a control method for controlling the high frequency power of two different frequencies, LF and HF, to control the quantity and quality of free radicals and ions.

[0052] [Overall structure of plasma processing device]

[0053] First, refer to Figure 1 , an example of a plasma processing apparatus 1 according to an embodiment will be described. Figure 1 FIG. 1 is a diagram showing an example of a plasma processing apparatus according to an embodiment.

[0054] A plasma processing apparatus 1 according to one embodiment is a capacitive coupling type parallel plate plasma processing apparatus, and includes, for example, a cylindrical processing container 10 formed of aluminum having an anodized surface. The processing container 10 is grounded.

[0055] A cylindrical support table 14 is disposed at the bottom of the processing container 10 via an insulating plate 12 made of ceramic or the like, and a mounting table 16 made of, for example, aluminum is disposed on the support table 14. The mounting table 16 constitutes a lower electrode, and a wafer W as an example of a processing object is mounted thereon via an electrostatic chuck 18.

[0056] An electrostatic chuck 18 for holding the wafer W by electrostatic force is provided on the upper surface of the mounting table 16. The electrostatic chuck 18 has a structure in which an electrode 20 made of a conductive film is sandwiched between a pair of insulating layers or insulating sheets. The electrode 20 is connected to a DC power supply 22. A DC voltage output from the DC power supply 22 is applied to the electrode 20. The wafer W is held by electrostatic force such as Coulomb force generated thereby.

[0057] On the upper surface of the mounting table 16, a conductive edge ring 24 made of, for example, silicon is disposed around the wafer W. The edge ring 24 is also called a focus ring. On the side surfaces of the mounting table 16 and the support table 14, a cylindrical inner wall member 26 made of, for example, quartz is provided.

[0058] A refrigerant chamber 28 is provided in a ring shape, for example, inside the support table 14. A refrigerant such as cooling water at a predetermined temperature is circulated and supplied to the refrigerant chamber 28 from a cooling unit provided outside through pipes 30a and 30b, and the processing temperature of the wafer W on the mounting table 16 is controlled by the temperature of the refrigerant. The refrigerant is an example of a temperature regulating medium circulated and supplied to the pipes 30a and 30b, and the temperature regulating medium can not only cool the mounting table 16 and the wafer W, but can also heat them in some cases.

[0059] In addition, a heat-conducting gas such as He gas is supplied from a heat-conducting gas supply mechanism to between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W via the gas supply passage 32 .

[0060] An upper electrode 34 is provided above the mounting table 16 in parallel to face the mounting table 16. A plasma processing space is formed between the upper electrode 34 and the lower electrode. The upper electrode 34 forms a surface that faces the wafer W on the mounting table 16 and contacts the plasma processing space, that is, an opposing surface.

[0061] The upper electrode 34 is supported on the upper part of the processing container 10 via an insulating shielding member 42. The upper electrode 34 includes an electrode plate 36 and an electrode support 38. The electrode plate 36 constitutes an opposite surface to the mounting table 16 and has a plurality of gas release holes 37. The electrode support 38 supports the electrode plate 36 in a manner that the electrode plate 36 can be detached and is formed of a conductive material such as aluminum with an anodized surface. The electrode plate 36 can be formed of, for example, silicon or SiC. A gas diffusion chamber 40 is provided inside the electrode support 38, and a plurality of gas flow holes 41 connected to the gas release holes 37 extend from the gas diffusion chamber 40 from below.

[0062] A gas inlet 62 for introducing a processing gas into the gas diffusion chamber 40 is formed in the electrode support 38, and a gas supply pipe 64 is connected to the gas inlet 62, and a processing gas supply source 66 is connected to the gas supply pipe 64. A mass flow controller (MFC) 68 and an on-off valve 70 are sequentially arranged in the gas supply pipe 64 from the upstream side. In this way, the processing gas for etching can be supplied from the processing gas supply source 66. The processing gas reaches the gas diffusion chamber 40 from the gas supply pipe 64, and is released into the plasma processing space in a shower shape from the gas release hole 37 through the gas flow hole 41. In this way, the upper electrode 34 acts as a shower head for supplying the processing gas.

[0063] The upper electrode 34 is connected to the variable DC power supply 50, and a DC voltage from the variable DC power supply 50 can be applied to the upper electrode 34. The polarity, current and voltage of the variable DC power supply 50, and the control of the electronic switch that turns on and off the current and / or voltage are controlled by the control unit 200.

[0064] The mounting table 16 is connected to a first high frequency power source 48 via a power supply rod 47 and a matching device 46. The first high frequency power source 48 applies LF power to the mounting table 16. Thus, ions are attracted to the wafer W on the mounting table 16. The first high frequency power source 48 outputs LF power with a frequency in the range of 200 kHz to 13.56 MHz. The matching device 46 matches the internal impedance of the first high frequency power source 48 with the load impedance.

[0065] The stage 16 is connected to the second high frequency power supply 90 via the power supply rod 89 and the matching device 88. The second high frequency power supply 90 applies HF power to the stage 16. The frequency of HF is higher than the frequency of LF, and HF power with a frequency of 13.56 MHz or more is output from the second high frequency power supply 90. For example, HF power of 100 MHz, which is higher than the LF power of 400 kHz, can be output. The matching device 88 matches the internal impedance of the second high frequency power supply 90 with the load impedance. The stage 16 can be connected to a filter 94 for grounding a specified high frequency. In addition, the HF power supplied from the second high frequency power supply 90 can also be applied to the upper electrode 34.

[0066] An exhaust port 80 is provided at the bottom of the processing container 10, and the exhaust port 80 is connected to an exhaust device 84 via an exhaust pipe 82. The exhaust device 84 has a vacuum pump such as a turbomolecular pump, which can reduce the pressure in the processing container 10 to a desired vacuum degree. In addition, a wafer W delivery port 85 is provided on the side wall of the processing container 10, and the delivery port 85 can be opened and closed by a gate valve 86. In addition, a sediment shield 11 is provided along the inner wall of the processing container 10 in a detachable manner, and the sediment shield 11 is used to prevent the etching byproduct (sediment) from adhering to the processing container 10. That is, the sediment shield 11 constitutes the wall of the processing container. In addition, the sediment shield 11 is also provided on the outer periphery of the inner wall member 26. An exhaust plate 83 is provided between the sediment shield 11 on the processing container wall side of the bottom of the processing container 10 and the sediment shield 11 on the inner wall member 26 side. As the deposit shielding member 11 and the exhaust plate 83, a member obtained by coating an aluminum material with ceramic such as Y2O3 can be used.

[0067] When etching is performed in the plasma processing apparatus of the above structure, first, the gate valve 86 is opened, and the wafer W to be etched is introduced into the processing container 10 through the introduction and delivery port 85 and placed on the mounting table 16. Then, the processing gas used for etching is supplied from the processing gas supply source 66 to the gas diffusion chamber 40 at a prescribed flow rate, and is supplied into the processing container 10 through the gas flow hole 41 and the gas release hole 37. In addition, the processing container 10 is exhausted by the exhaust device 84 so that the pressure therein is set to a value within the range of, for example, 0.1 to 150 Pa. Here, various gases that have been used so far can be used as the processing gas, for example, gases containing halogen elements such as C4F8 gas can be preferably used. In addition, other gases such as Ar gas and O2 gas can also be contained.

[0068] In the state where the etching gas is introduced into the processing container 10 as described above, HF power is applied to the mounting table 16 from the second high frequency power supply 90. In addition, LF power is applied to the mounting table 16 from the first high frequency power supply 48. In addition, a DC voltage is applied to the upper electrode 34 from the variable DC power supply 50. In addition, a DC voltage is applied to the electrode 20 from the DC power supply 22, and the wafer W is adsorbed and held on the mounting table 16.

[0069] The processing gas released from the gas release hole 37 of the upper electrode 34 is mainly dissociated and ionized by the HF power to generate plasma. The free radicals and ions in the plasma are used to etch the processing surface of the wafer W. In addition, by applying LF power to the mounting table 16, the ions in the plasma are controlled, so that etching of holes with a high aspect ratio can be performed, etc., and the control margin of the plasma can be expanded.

[0070] The plasma processing device 1 is provided with a control unit 200 for controlling the operation of the entire device. The control unit 200 performs the desired plasma processing such as etching according to the scheme stored in a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory). In the scheme, control information of the device corresponding to the processing conditions is set, that is, the processing time, pressure (gas exhaust), high frequency power and / or voltage, various gas flow rates, the temperature in the processing container (upper electrode temperature, side wall temperature of the processing container, wafer W temperature, electrostatic chuck temperature, etc.), the temperature of the refrigerant output from the cooler, etc. In addition, the above-mentioned program and the scheme for giving the processing conditions can be stored in a hard disk or a semiconductor memory. In addition, the scheme can also be set at a predetermined position in a state where it is stored in a storage medium readable by a mobile computer such as a CD-ROM or DVD so that it can be read.

[0071] It is also possible to control the on / off or high / low of the HF power to be synchronized with the phase of a signal synchronized with the high frequency cycle of the bias power, or any one of the voltage, current or electromagnetic field measured in the bias power supply system within one cycle. For example, the control unit 200 may control the on / off or high / low of the HF power to be synchronized with the phase of a voltage or current within one cycle of the LF. In this way, the quantity and quality of ions and free radicals can be controlled. In addition, the generation of IMD can be reduced.

[0072] The bias power supply system refers to the first high-frequency power supply 48 → matching box 46 → power supply rod 47 → mounting table 16 → (plasma) → upper electrode 34 → (ground). Any of the voltage, current or electromagnetic field measured in the bias power supply system refers to the voltage, current or electromagnetic field measured in the portion from the first high-frequency power supply 48 through the inside of the matching box 46 and the power supply rod 47 to the mounting table 16 and the upper electrode 34.

[0073] In addition, the state of the signal synchronized with the high frequency cycle of the bias power, or any of the voltage, current, or electromagnetic field measured in the bias power supply system is also referred to as the "reference electrical state". The HF power (generated source power) is controlled to be applied alternately in the first state and the second state described later in synchronization with the phase within one cycle of the reference electrical state.

[0074] However, when any one of the voltage, current or electromagnetic field measured in the bias power supply system is used as the "reference electrical state", the reference electrical state is preferably any one of the voltage, current or electromagnetic field measured in any component from the lower electrode 16 to the inside of the matching device connected via the power supply rod 47.

[0075] As a method for measuring a reference electrical state in a bias power supply system, a method can be cited in which a voltage probe, a current probe, or a BZ probe (a probe for measuring an induced magnetic field) is set near any component of the bias power supply system to measure the voltage, current, or induced magnetic field of each component.

[0076] For example, Figure 2B (a) is an example of a case where any one of the voltage, current or electromagnetic field measured by the bias power supply system is used as the "reference electrical state". Figure 2BIn (a), the processor 100 inputs any one of the HF voltage or current, the LF voltage or current, the HF phase signal, or the LF phase signal from a sensor such as a VI probe installed in the power supply system. The processor 100 applies the generated source power alternately in the first state and the second state in synchronization with the phase within one cycle of the reference electrical state, and the reference electrical state represents any one of the input HF voltage or current, the LF voltage or current, the HF phase signal, or the LF phase signal.

[0077] The processor 100 may generate a signal synchronized with the high frequency cycle of the bias power output from the first high frequency power supply 48 instead of the signal from the sensor. In this case, the state of the signal can be used as the reference electrical state. In addition, the step of measuring the reference electrical state in the bias power supply system can be omitted. For example, Figure 2B In (b), the processor 100 inputs the phase signal (low power waveform) of LF or the signal related to the information of the bias power from the first high frequency power source 48, and generates a signal synchronized with the period of the high frequency of the bias power based on the input signal. The processor 100 outputs the generated signal to the second high frequency power source 90. The second high frequency power source 90 generates source power alternately in the first state and the second state based on the signal.

[0078] In addition, the processor 100 may generate a signal synchronized with the high frequency cycle of the bias power instead of the signal from the first high frequency power source 48. In this case, the processor 100 generates a signal having, for example, Figure 3 A signal with a period shown in LF is generated synchronously with the signal, for example Figure 3 The processor 100 outputs the generated signal to the first high frequency power supply 48 and the second high frequency power supply 90. The first high frequency power supply 48 outputs bias power based on the signal. The second high frequency power supply 90 applies the generated source power alternately in the first state and the second state based on the signal.

[0079] In addition, the mounting table 16 is an example of a first electrode on which the wafer W is mounted. The upper electrode is an example of a second electrode opposite to the first electrode. The first high-frequency power supply 48 is an example of a bias power supply for supplying LF power to the first electrode. The second high-frequency power supply 90 is an example of a generating source power supply for supplying HF power having a frequency higher than LF power to the first electrode or the second electrode. The control unit 200 is an example of a control unit for controlling the bias power supply and the generating source power supply. The potential of the lower electrode (mounting table 16) to which the bias power is applied is also referred to as the lower electrode potential.

[0080] [Structure of the control unit]

[0081] Reference Figure 2A, the specific structure of the control unit 200 is described. The control unit 200 includes a processor 100, a signal generating circuit 102, directional couplers 105, 108, a reflection detector 111, and an oscilloscope 112.

[0082] A directional coupler 105 is connected between the first high frequency power source 48 and the matching device 46 in the power supply line of the first high frequency power source 48. A directional coupler 108 is connected between the second high frequency power source 90 and the matching device 88 in the power supply line of the second high frequency power source 90.

[0083] The directional coupler 105 transmits a part of the traveling wave power (Pf) of LF to the oscilloscope 112. In addition, the directional coupler 108 transmits a part of the traveling wave power and the reflected wave power of HF to the oscilloscope 112.

[0084] In one embodiment, the LF frequency shown by the oscilloscope 112 is, for example, 400 kHz, and the HF frequency is, for example, 100 MHz. Thus, the oscilloscope 112 can observe the waveforms of the LF traveling wave power, the HF traveling wave power, and the HF reflected wave power.

[0085] In addition, the directional coupler 108 separates a certain proportion of the reflected wave of HF and sends it to the reflection detector 111. The reflection detector 111 is composed of, for example, a spectrum analyzer, a power meter, etc., and measures how much IMD (Inter modulation distortion) of what wavelength is generated and whether it is a certain degree of reflected wave power. IMD is the reflected wave power from the plasma side generated according to the frequency of the sum or difference of the fundamental wave and / or harmonics of LF and the fundamental wave and / or harmonics of HF, and the fundamental wave and / or harmonics of LF and the fundamental wave and / or harmonics of HF are generated by applying HF power to the upper electrode or the lower electrode of the plasma processing device 1 (in one embodiment, the lower electrode) and applying LF power to the lower electrode.

[0086] The directional coupler 105 sends a part of the traveling wave power of the LF to the processor 100. The processor 100 generates a synchronization signal for HF that is synchronized with the traveling wave power of the LF. For example, the processor 100 may also generate a synchronization signal for HF in synchronization with the period when the traveling wave of the LF is positive. In addition, instead of the directional coupler 105, the waveform of the LF detected by a sensor such as a VI probe may be sent to the processor 100.

[0087] The processor 100 sends the generated synchronization signal to the signal generating circuit 102. The signal generating circuit 102 generates a control signal synchronized with the LF traveling wave power according to the sent synchronization signal, and sends it to the second high frequency power source 90 and the first high frequency power source 48.

[0088] There are two methods for generating the control signal. When the first high frequency power supply 48 is a normal power supply, the directional coupler 105 takes out a part of the voltage or current of the LF output from the first high frequency power supply 48 as a waveform and inputs it to the processor 100. However, this is not limited to this, and the processor 100 can directly input a part of the LF power, etc. from the first high frequency power supply 48. The processor 100 generates a connection signal with an arbitrary delay and an arbitrary amplitude based on the input waveform signal, and sends it to the signal generating circuit 102. The connection signal is an example of a synchronization signal.

[0089] The signal generating circuit 102 issues a command signal to the second high frequency power source 90 to generate HF power while receiving the on signal. The command signal may be a control signal for generating HF power during the on signal according to the input form of the high frequency power source 48, or the on signal itself.

[0090] In the case where the first high-frequency power source 48 is an amplifier that amplifies LF power, voltage, or current, the signal from the directional coupler 105 may not be used, and the signal generating circuit 102 may extract a portion of the LF power outputted from the first high-frequency power source 48 as a waveform, and generate an on signal having an arbitrary delay and an arbitrary amplitude based on the signal of the waveform. The signal generating circuit 102 transmits the signal of the waveform and the on signal to the second high-frequency power source 90.

[0091] However, the above control signal generation method is only an example and is not limited to this. As long as such a control signal can be generated, that is, a control signal that controls the HF power to be alternately applied in synchronization with the phase within one cycle of the reference electrical state (the phase within one cycle of the LF voltage or current, the electrode potential, etc.), is not limited to Figure 2A The circuit of the control unit 200 shown may be implemented using other hardware or software.

[0092] The amplifier of the first high frequency power source 48 amplifies the amplitude (AM: amplitude modulation) of the 400 kHz LF modulation signal and supplies it to the lower electrode. The amplifier of the second high frequency power source 90 amplifies the amplitude of the 100 MHz HF modulation signal and supplies it to the lower electrode.

[0093] Figure 3This is a diagram showing an example of the voltage or current of HF applied in accordance with the waveform of the voltage or current of LF and the period when the voltage or current of LF is positive. When the electrode potential shown in the second waveform from the bottom is positive, the voltage or current of HF is controlled (turned on) to a positive value. When the electrode potential is negative, the voltage or current of HF is controlled (turned off) to 0. Basically, the electrode potential is determined by the voltage or current of LF, so the voltage or current of HF is turned off when the voltage or current of LF is negative, and the voltage or current of HF is turned on when the voltage or current of LF is positive.

[0094] The processor 100 may generate a synchronization signal for controlling HF power in a time period including a period when the electrode potential is positive. However, the processor 100 is not limited thereto and may generate a synchronization signal for controlling HF power in a short time period including a moment when the electrode potential becomes most negative.

[0095] [HF power supply period]

[0096] Below, refer to Figure 4 , a supply period of HF power according to one embodiment is described. Figure 4 This is a diagram showing an example of the supply period of HF power according to one embodiment.

[0097] Figure 4 The vertical axis of (a) to (c) represents the potential of the electrode. The potential of the electrode is roughly the same as the potential of the chip. The potential of the electrode is the potential when the voltages of LF and HF are superimposed. Here, the Vpp of the LF voltage with a frequency of 400kHz is significantly greater than the Vpp of the HF voltage with a frequency of 100MHz. Therefore, basically, the electrode potential is determined by the voltage of LF and vibrates with the amplitude (amplitude) of the Vpp of the HF voltage.

[0098] Regarding the sheath layer above the electrode, the thickness of the sheath layer is basically determined by the voltage of LF. When the voltage of LF is negative, the electrode potential becomes deeper in the negative direction than when the voltage of LF is positive due to the so-called self-bias voltage Vdc. When the electrode potential is positive relative to the ground potential, it is close to the plasma potential, so some high-speed electrons can flow into the electrode, and when the electrode potential is negative relative to the ground potential, ions flow in.

[0099] The electrode is floated on the ground by means of a blocking capacitor (a matching device in one embodiment), so that the electrons flowing into the electrode do not flow to the ground. Thus, in the period (half cycle) when the surface of the electrode is at a positive potential relative to the plasma, electrons flow into the electrode and accumulate therein. However, due to the accumulated electrons, the surface of the electrode is negatively charged, and a negative bias is generated relative to the plasma. Due to the negative bias, ions can flow into the surface of the electrode. Thus, a sheath can be formed on the surface of the electrode.

[0100] Eventually, the surface of the electrode approaches the plasma potential. When the electrons flowing in at this time are balanced with the ions flowing in steadily due to the negative bias, the DC component of the electrode potential becomes the self-bias voltage Vdc.

[0101] Figure 3 The electrode potential corresponding to the phase of LF, the plasma potential corresponding to the phase of LF, the sheath thickness, and the impedance Z are schematically shown. The plasma potential is slightly higher than the highest potential in the processing container 10. Therefore, when the electrode voltage is positive, the plasma potential becomes slightly higher than the electrode potential, and when the electrode potential is negative, if the potential of the wall of the processing container 10 is set to 0, the plasma potential is slightly higher than the potential of the wall surface 0.

[0102] When the voltage of LF is negative due to the self-bias voltage Vdc, the electrode potential becomes deeper in the negative direction. The thickness of the sheath is proportional to the voltage, so when the electrode potential is negative, a larger voltage is applied to the electrode, and the thickness of the sheath becomes thicker. On the other hand, when the electrode voltage is positive, a smaller voltage is applied to the electrode than when the electrode potential is negative, so the thickness of the sheath becomes thinner.

[0103] In one embodiment, since LF power and HF power are applied to the mounting table 16 (lower electrode), Figure 4 The electrode potential shown becomes the potential of the lower electrode. Corresponding to the phase of LF, there are periods when the thickness of the sheath above the mounting table 16 is in a roughly flat and thin state, and periods when the sheath is in a thick state. Therefore, if the sheath is assumed to be a capacitor, the capacitance of the capacitor becomes larger when the sheath is thinner, and according to the impedance Z=1 / ωC, it can be seen that the impedance Z of the sheath becomes lower. That is, when the electrode voltage is positive, the sheath is thinner, so the impedance Z is low and is roughly constant. On the other hand, when the electrode potential is negative, the sheath is thicker, so the impedance Z is high and changes more. Moreover, the impedance Z is roughly determined by the voltage of LF. Based on the above, impedance matching of HF power becomes difficult. In particular, when the electrode potential is negative, that is, when the voltage of LF is negative, the impedance is high and changes greatly, so impedance matching of HF power becomes difficult.

[0104] With respect to such a change in impedance Z, the matching device 88 that performs impedance matching on the HF power can track a frequency up to about 1 Hz by operating the motor, but it is difficult to track and obtain matching at frequencies above this, and it matches at one moment in the impedance that changes from time to time according to the phase of the LF. In this state, the matching device 88 cannot match at other phases other than the one moment that has been matched, so the reflected wave power of the IMD is large.

[0105] Therefore, in one embodiment, if Figure 4 (a) and Figure 4 As shown in (b), when the electrode potential is positive, the HF power is controlled to be turned on or at a high level (High), and when the electrode potential is negative, the HF power is controlled to be turned off or at a low level (Low).

[0106] In one embodiment, when the electrode voltage is positive, the impedance Z is substantially constant, so it is easy to obtain matching if HF power is supplied during this period. Therefore, the HF power is controlled to be turned on or at a high level during this period. On the other hand, when the electrode potential is negative, the impedance is high and varies greatly, so it is difficult to obtain matching even if HF power is supplied during this period. Therefore, the supply of HF power is controlled to be turned off or at a low level during this period. Thus, the generation of IMD can be reduced.

[0107] like Figure 4 As shown in (b), when the HF power is controlled to a high level or a low level, the HF power is not turned off during the period when the electrode potential is negative but is kept at a low level, so that the plasma density can be suppressed compared to the case where the HF power is controlled to be turned on or off. In addition, by making the HF power applied during the period when the electrode potential is negative smaller than the HF power applied during the period when the electrode voltage is positive, the generation of IMD can be suppressed.

[0108] However, the control method of controlling the HF power to be turned on or at a high level in accordance with the period when the electrode voltage is positive is only an example and is not limited to this. The HF power can also be controlled to be turned on or at a high level when at least a part of the phase of the reference electrical state is positive. In addition, the HF power can also be controlled to be turned on or at a high level when at least a part of the phase of the reference electrical state is negative. That is, the HF power (generated source power) has a first state and a second state smaller than the first state, and the period of the first state can include the moment when the phase of the reference electrical state becomes a peak. The peak in this case can be a positive peak or a negative peak. In addition, the period of the first state can include a period when at least a part of the phase of the reference electrical state is positive. In addition, the period of the first state can include a period when at least a part of the phase of the reference electrical state is negative. In addition, with respect to the HF power, not only a rectangular wave consistent with the period when the phase of the reference electrical state is positive can be applied, but also a roughly rectangular wave including at least one of a slow rise (slow up) of the rising part and a slow fall (slowdown) of the falling part can be applied. Alternatively, the HF power may be applied at least at one of a period shifted backward by a predetermined time or a period shifted forward by a predetermined time from the period when the phase of the reference electrical state is positive.

[0109] As an application example of a control method for shifting the HF power by a predetermined time from the period when the phase of the reference electrical state is positive, the following situation can be cited. If the HF power is applied only when the phase of the reference electrical state is positive, the ion energy becomes small. Depending on the type of etching, sometimes a larger ion energy treatment is desired. In this case, the reference electrical state of the LF changes from positive to negative, and the HF power is applied until the desired ion energy is obtained. Thus, a treatment with large ion energy can be achieved.

[0110] In addition, the duration of HF power supply may be adjusted by reducing or increasing a predetermined time based on the period when the phase of the reference electrical state is positive. For example, in addition to the period when the phase of the reference electrical state is positive, a predetermined time is added before or after the period, and HF power is supplied during this period.

[0111] HF power may also be supplied during the period when the phase of the reference electrical state is negative. However, during the period when the phase of the reference electrical state is negative, the impedance is high and changes with time. Therefore, in this case, it is preferred to control the HF power to be turned on for a shorter time width during the period when the phase of the reference electrical state is negative. For example, it is preferred to adjust the period and amplitude of applying HF power by a circuit having a window function or a delay function. In advance, the reflection intensity in one cycle of the reference electrical state is measured, and based on the measurement result, a circuit having an automatic adjustment function is used to control the application of HF power during the period when the reflection of LF power is small.

[0112] For example Figure 4 As shown in (c), when the electrode potential is negative, the HF power may be turned on or made high in a short time width including the time when the electrode self-bias Vdc becomes maximum in the negative direction, and the HF power may be turned off or made low in other time periods. In addition, the reflected wave power may be detected in advance, and according to its size, the HF power may be turned off or made low in a time period with a large reflected wave power, and the HF power may be turned on or made high in a time period with a small reflected wave power. Figure 4 By applying HF power for a short time during the time width when the electrode potential shown in (c) becomes the most negative, strong ion implantation can be achieved in specific etching such as HARC (High Aspect Ratio Contact), thereby improving the etching speed and etching shape.

[0113] As described above, according to the control method of the plasma processing device 1 of one embodiment, the on / off or high / low of the HF power is controlled synchronously with the phase within one cycle of the reference electrical state. Thus, the generation of IMD can be reduced. In addition, the ion energy can be controlled, and the quantity and quality of free radicals and ions can be controlled.

[0114] In addition, if Figure 3 and Figure 4 (a)~ Figure 4 As shown in an example of (c), the state in which the HF power is controlled to be on or a high level is an example of the first state, and the state in which the HF power is controlled to be off or a low level is an example of the second state.

[0115] In a control method of a plasma processing apparatus 1 according to an embodiment, a first control step is included in which a first state and a second state are alternately applied in synchronization with a phase within a period of a reference electrical state. The second state may be smaller than the first state, and the power of the second state may be 0 or a value other than 0 and smaller than the first state.

[0116] [An example of the effect]

[0117] Below, refer to Figure 5 to Figure 7 , an example of the effect of controlling the on / off or high / low of HF power in synchronization with the phase within one cycle of the reference electrical state is described. Figure 5 The graph of FIG. 1 is a diagram showing an example of the relationship among the phase of LF, the plasma density Ne, and the absolute value |Vdc| of the self-bias according to one embodiment. Figure 6 and Figure 7 This is a diagram showing an example of reflected wave power according to one embodiment.

[0118] Figure 5 The graph shows the actual measurement results obtained by changing the phase and periodically applying HF power in a time width of about 40% of one cycle relative to one cycle of the reference electrical state. The left vertical axis of the graph shows the plasma density Ne (cm -3 ), and the right vertical axis represents the absolute value of the self-bias |Vdc| (V). When HF power and LF power are superimposed on the lower electrode of the plasma processing device 1, the sheath of the lower electrode changes according to the period of LF, resulting in a change in impedance Z, and a change in plasma density Ne and self-bias Vdc.

[0119] When the HF power is turned on during the period when the electrode potential is positive and the HF power is turned off during the period when the electrode potential is negative (refer to Figure 5 ), such as Figure 5 As shown in region a of the lower graph, the plasma density Ne becomes high, and the plasma generation efficiency can be improved. In region a, the absolute value |Vdc| of the self-bias becomes low, and the generation of IMD can be effectively suppressed.

[0120] In addition, when the HF power is turned off during the period when the electrode voltage is positive, and the HF power is turned on for a short period including when the electrode potential becomes the maximum in the negative direction (see Figure 5 ), such as Figure 5 As shown in area b of the lower graph, the plasma density Ne becomes medium to high, and the plasma generation efficiency becomes medium or above. This is because when the electrode potential is negative, a large voltage is applied to the electrode, the thickness of the sheath increases, and the HF electric field decreases when the HF power is turned on, which reduces the plasma generation efficiency.

[0121] In addition, in region b, the absolute value |Vdc| of the self-bias becomes high, and ions with monochromatic ion energy, i.e., ions with uniform ion energy, can be attracted to the wafer W. In particular, in high aspect ratio processing, monochromatic high-energy ions can be attracted to the wafer W. At this time, IMD is likely to occur, but by applying HF power for a short time when the potential of the lower electrode becomes the maximum in the negative direction, the occurrence of IMD can be reduced as a whole compared to the case where HF power is applied all the time.

[0122] As described above, according to the plasma processing apparatus 1 of one embodiment, for example, the HF power is controlled to be turned on or at a high level based on the period when the electrode voltage is positive, so that the generation of IMD can be reduced. In addition, the sheath becomes thicker and the plasma generation efficiency decreases during the period when the electrode potential is negative as a technical problem, and the plasma generation efficiency can be improved by applying the HF power during the period when the electrode potential is positive.

[0123] In addition, by applying HF power for a short time at the time when the electrode potential is the deepest negative, the monochromated high-energy ions can be attracted to the wafer W.

[0124] For example Figure 6 The up and down charts on the left and Figure 6 The waveforms of the screens (a) and (b) on the right side show an example of the detection results of the reflection detector 111 of the control unit 200 and the display results of the oscilloscope 112. The lower left graph shows the Vpp and Vdc of one cycle of LF. The deeper the Vdc is in the negative direction, the thicker the sheath becomes, and the plasma generation efficiency when the HF power is applied decreases. The upper graph shows the HF traveling wave power (Pf) and the reflected wave power (Pr) corresponding to the Vpp and Vdc of one cycle of LF.

[0125] Figure 6 An example of the display of the oscilloscope 112 of (a) shows the waveform A of the LF traveling wave power measured when the phase of LF is 180° shown in area c, and the amplitude B of the high frequency power on the chip (i.e., the total value of the LF power and the HF power). In addition, the waveform of the HF traveling wave power is represented by C, and the waveform of the HF reflected wave power is represented by D. In addition, Figure 6 (b) is an example of the display of the oscilloscope 112, showing the waveform A of the LF traveling wave power, the amplitude B of the high-frequency power on the chip, the waveform C of the HF traveling wave power and the waveform D of the HF reflected wave power measured when the phase of the LF shown in area d is 0° (= 360°).

[0126] Accordingly, in region d, the reflected wave power is smaller than that in region c. It can be seen that the generation of IMD can be suppressed by alternately applying HF power in a manner that makes the HF power a first state (e.g., turned on or a high level state) and a second state (e.g., turned off or a low level state) in synchronization with the phase within one cycle of the reference electrical state, wherein the reference electrical state is a signal synchronized with the cycle of the high frequency of the bias power in a manner that the phase of the LF includes 0°, or a signal measured by the power supply system of the bias power. For example, as described above, the HF power is set to the first state corresponding to the period when the electrode voltage is positive, and the HF power is set to the second state corresponding to the period when the electrode potential is negative, thereby performing control corresponding to the absolute value |Vdc| of the self-bias, which can suppress IMD and improve plasma generation efficiency. In addition, by controlling the HF power to the first state and the second state at any period according to the electrode potential, it is possible to attract high-energy ions to the wafer W using the region with a high plasma density Ne and the region with a large absolute value |Vdc| of the self-bias. In addition, in this case, by applying the HF power in a pulsed state, the generation of IMD can be reduced as a whole.

[0127] Figure 7An example of LF Vpp, LF|Vdc|, HF traveling wave power (Pf), and HF reflected wave power (Pr) is shown. According to this, the maximum change of HF reflected wave power (Pr) in the phase of one cycle of LF voltage is about 5 times (about 10W to about 50W). According to the above, by controlling the HF power in synchronization with the phase within one cycle of the reference electrical state, it is possible to reduce IMD to 1 / 5. In addition, it can be seen that for LF Vpp and LF|Vdc|, by controlling the HF power in synchronization with the phase within one cycle of the reference electrical state, it can be changed within a range of about 1.6 times the minimum value.

[0128] [Modifications]

[0129] Below, refer to Figure 8 to Figure 11 , a control method of Modifications 1 to 4 of one embodiment is described. Figure 8 It is a diagram for explaining a control method according to Modification 1 of one embodiment. Fig. 9 It is a diagram for explaining a control method according to a second modification of an embodiment. Fig.10 It is a diagram for explaining a control method according to a third modification of one embodiment. Fig.11 It is a diagram for explaining a control method according to a fourth modification of an embodiment.

[0130] (Variant 1)

[0131] In the above-described embodiment, when the HF power is pulse-modulated in synchronization with the phase within one cycle of the reference electrical state (see Figure 3 When HF AM modulation is used, an HF power supply that performs pulse modulation at the same frequency as the LF frequency is required, which may increase the cost.

[0132] Therefore, in the plasma processing apparatus 1 of the modification example 1, as Figure 8 As shown in (a), an additional circuit 250 constituting a bypass line is installed on the power supply line or the lower electrode connected to the first high frequency power supply 48 and the second high frequency power supply 90. In the additional circuit 250, the power supply rod connected to the lower electrode is connected in series with the coil 252 and the variable capacitor 251, and the variable capacitor 251 is connected to the processing container 10 and grounded.

[0133] The additional circuit 250 can increase the ratio of the impedance on the processing container 10 side to the load impedance on the plasma side. Therefore, even if the impedance changes, the additional circuit 250 can alleviate the situation where the impedance Z obtained by adding the additional circuit 250 and the impedance on the processing container 10 side changes significantly compared to the case where the additional circuit 250 is not provided. Figure 8As shown in (b), by using an additional circuit 250 to reduce the change in the total impedance Z, when the HF power is applied in phase synchronization with one cycle of the reference electrical state, the generation of IMD can be further suppressed. In addition, by simply installing the additional circuit 250, a structure for suppressing IMD can be simply and inexpensively constructed. In addition, when the additional circuit 250 is inserted into the second high-frequency power supply 90 side after the power supply pole branches, the HF power is not easily affected by the LF power, so it is preferred. If a filter is provided between the first high-frequency power supply 48 and the second high-frequency power supply 90, the HF power is less susceptible to the LF power, the change in the total impedance Z can be reduced, and the generation of IMD can be further suppressed. The additional circuit 250 may include at least any one element of a coil, a capacitor, or a diode.

[0134] (Variant 2)

[0135] In the plasma processing apparatus 1 of the second modification, as Fig. 9 As shown in (a), an impedance changing circuit 300 is installed on the power supply line or the lower electrode connected to the first high frequency power supply 48 and the second high frequency power supply 90. The impedance changing circuit 300 can change the impedance so that the combined impedance of the load impedance on the plasma side and the impedance of the impedance changing circuit 300 becomes constant. Alternatively, the impedance changing circuit 300 changes the impedance according to the phase of LF to suppress the change of impedance observed from the matching device 88. In this way, the reflected wave power can be suppressed and the generation of IMD can be reduced. The impedance changing circuit 300 changes the impedance within one cycle of the reference electrical state according to the phase (or impedance) of LF, the Vdc of LF, or the reflected wave power, etc., so that IMD can be suppressed.

[0136] As an example of the impedance varying circuit 300 , a configuration in which capacitors are arranged in a matrix and connections of the capacitors are switched using electronic switches can be cited. The control unit 200 controls the electronic switches to vary the impedance of the impedance varying circuit 300 .

[0137] The control unit 200 switches the connection of the capacitor of the impedance changing circuit 300 so that, for example, Fig. 9 As shown in (b), the change in impedance Z, which is the sum of the load impedance on the plasma side and the impedance of the impedance changing circuit 300, is reduced. Thus, when HF power is applied in phase synchronization with one cycle of the reference electrical state, impedance matching becomes good, and the generation of IMD can be further suppressed.

[0138] The impedance changing circuit 300 can be inserted inside the matching device 88 and integrated with the matching device 88. When the impedance changing circuit 300 is inserted into the second high frequency power supply 90 side after the power supply rod is branched, the HF power is not easily affected by the LF power, so it is preferred. If a filter is provided between the first high frequency power supply 48 and the second high frequency power supply 90, the HF power is less likely to be affected by the LF power, the change of the total impedance Z can be reduced, and the generation of IMD can be further suppressed.

[0139] (Variant 3)

[0140] In variation 3, if Fig.10 As shown in (a), an electromagnet 350 is provided on the upper portion of the processing container 10. The position of the electromagnet 350 is not limited to Fig.10 The position of (a) can be any part of the processing container 10, for example, it can be inside the processing container 10. The control unit 200 controls the strength of the electromagnet 350 according to the phase (or impedance) of the reference electrical state, the phase of LF, the electrode potential to which the bias power is applied, LF Vdc or the reflected wave power of HF, thereby changing the characteristics of the magnetic field. Fig.10 As shown in (b), the magnetic field is enhanced when the LF Vdc is negative when the sheath becomes thicker, and the magnetic field is weakened or eliminated when the LF Vdc is positive when the sheath becomes thinner, so as to reduce the change in impedance Z. As a result, the generation of IMD can be further suppressed. In addition, the electromagnet 350 can use a multi-pole electromagnet or a fixed magnet, and is an example of a magnetic field generating unit that generates a magnetic field. The control performed by the electromagnet 350 shown in Modification Example 3 can be combined with the control performed by the additional circuit 250 of Modification Example 1 or the impedance change circuit 300 of Modification Example 2.

[0141] (Variant 4)

[0142] When the thickness of the sheath changes, it seems that the electrostatic capacitance changes, and the resonance frequency of HF changes. The matching device 88 sums up all L components and C components of the inductance (inductance, such as the power supply rod, etc.) and conductance (conductance, such as the sheath, etc.) in the processing container 10 to obtain matching so that resonance can be achieved at the frequency of HF.

[0143] Therefore, when the thickness of the sheath changes, the C component changes. Therefore, if the matching device 88 cannot re-match the C component due to the change in the thickness of the sheath, the reflected wave power increases. However, since the matching device 88 needs to take about 1 second to change the variable capacitor, it may not be able to track the change in the thickness of the sheath and may not be able to correctly match.

[0144] Therefore, in Modification 4, the control unit 200 changes the frequency of HF according to the amount of change in the C component caused by the change in the sheath thickness. That is, based on the formula of the supply frequency of f(supply frequency)∝1 / √LC, the frequency f of HF is changed according to the change in the C component corresponding to the thickness of the sheath.

[0145] For example, assuming that the capacitance of the sheath on the electrode is C, when the capacitance C changes by 4 times due to the change in the thickness of the sheath, the frequency of HF changes by about 2 times. This allows a state in which the matching is substantially achieved due to the change in the thickness of the sheath.

[0146] In addition, when the capacitance C changes by 10 times according to the change in the thickness of the sheath layer, the frequency of HF changes by about 3.3 times. Thus, it is possible to obtain a state of approximately matching according to the change in the thickness of the sheath layer. That is, in the modification example 4, Fig.11 As shown in (a), the frequency of HF is changed based on the above-mentioned formula of the resonant frequency so as to match the change in the thickness of the sheath corresponding to the change in the voltage of LF for one cycle. As a result, a state of approximately matching is obtained according to the change in the thickness of the sheath, which can reduce the reflected wave power of HF and suppress the generation of IMD. In addition, in Modification 4, the second high-frequency power supply 90 uses a frequency variable power supply that can change the frequency of HF. In addition, the control shown in Modification 4 can also use at least any one of the additional circuit 250 of Modification 1, the impedance change circuit 300 of Modification 2, or the electromagnet 350 of Modification 3.

[0147] In addition, for all examples of the above-mentioned embodiments and the above-mentioned variations, the shift time and delay width can be adjusted based on any original signal or measurement signal such as the phase of LF, electrode potential, potential of the power supply system, Vdc, thickness of the electrode sheath, luminescence of plasma, reflection intensity of HF power, etc., using a circuit with a window function or a delay function.

[0148] Alternatively, the period of applying the HF power may be controlled not in synchronization with the phase of the LF voltage within one cycle, but in a manner such as Fig.11 (b) As shown, a pulsed power (hereinafter also referred to as "LF pulse") corresponding to the peak value of the LF voltage is applied, and the period of applying the HF power is controlled in accordance with the LF pulse. That is, for example, an LF pulse based on the 400 kHz LF may be applied in an on-off manner, and the HF power may be controlled in a pulsed form (HF pulse) in accordance with the LF pulse. Alternatively, a LF pulsed power corresponding to the peak value of the phase of the reference electrical state may be applied, and the period of applying the HF power may be controlled in accordance with the LF pulse.

[0149] As described above, the intensity of IMD varies depending on the LF power. Therefore, according to the control method of the plasma processing device 1 of the above embodiment and each of the above modifications, the generation of IMD can be reduced by selecting a period when the reflected wave power of HF is low and applying HF power during this period. By reducing the generation of IMD, the stability of the processing and plasma processing device 1 can be improved and the device cost can be reduced. In addition, the plasma density, self-bias Vdc, etc. can be controlled.

[0150] However, when the time of applying HF power becomes shorter, there is a possibility that the absolute amount of HF power decreases and the plasma density Ne becomes lower. Therefore, LF power and HF power may be applied at two moments including when the reference electrical state reaches two peaks within one cycle. In addition, the control method of applying HF power can be freely changed. In addition, the application of HF power is not limited to the lower electrode, and can be the upper electrode.

[0151] [Control method]

[0152] As described above, a control method of a parallel plate type plasma processing apparatus 1 according to an embodiment includes: a step of supplying bias power to a lower electrode on which a wafer W is mounted; and a step of supplying the generated source power to a plasma processing space by applying a generated source power having a frequency higher than the bias power to the lower electrode or the upper electrode. In the control method, the generated source power has a first state and a second state, and the control method includes a first control step of alternately applying the first state and the second state in synchronization with a phase within a cycle of a reference electrical state, the reference electrical state representing a signal synchronized with a cycle of the high frequency of the bias power, or any one of a voltage, a current, or an electromagnetic field measured by a bias power supply system.

[0153] The control method can also be performed by a plasma processing apparatus other than a parallel plate type plasma processing apparatus. The control method for a plasma processing apparatus other than a parallel plate type plasma processing apparatus includes: a step of supplying bias power to a lower electrode; and a step of supplying a generated source power having a frequency higher than the bias power to a plasma processing space. In the control method, the generated source power also has a first state and a second state, and the control method includes a first control step of alternately applying the first state and the second state in synchronization with the phase within one cycle of the reference electrical state.

[0154] [Variations 5-1 to 5-4]

[0155] Next, a control method of the plasma processing apparatus 1 according to Modifications 5-1 to 5-4 of one embodiment will be described. In Modifications 5-1 to 5-4, control is performed to intermittently stop the generation of source power and / or bias power. FIG. 13A to FIG. 13D It is a timing chart showing a control method of Modifications 5-1 to 5-4 of one embodiment.

[0156] exist Fig.13A In the modification 5-1, in addition to the first control step, a second control step is included, which intermittently stops the generated source power at a cycle independent of the cycle of the reference electrical state represented by the LF voltage as an example. The first control step and the second control step are repeatedly performed.

[0157] In Modification 5-1, the LF voltage is applied at the same cycle in the first control step and the second control step. On the other hand, regarding the generation source power, the first state and the second state are alternately repeated once or more in the first control step, and the generation source power is intermittently stopped between the first control steps in the second control step.

[0158] In the first control step and the second control step, the frequency of LF may be, for example, 0.1 Hz to 100 Hz. Also, the duty ratio (= fourth state / (third state+fourth state)) of the generated source power may be in the range of 1% to 90%.

[0159] The state of generating source power in synchronization with the cycle of the reference electrical state in the first control step is an example of the third state. The state of generating source power irrelevant to the cycle of the reference electrical state in the second control step is an example of the fourth state different from the third state.

[0160] Fig. 13B The control method of modification 5-2 includes, in addition to the first control step that is the same as modification 5-1, a third control step of intermittently stopping the bias power at a cycle that is independent of the cycle of the HF voltage or current. The state of the bias power in the third control step is an example of the fourth state.

[0161] In the modification 5-2, the first control step and the third control step are repeatedly performed. In the modification 5-2, the generated source power in the third control step repeatedly becomes the first state and the second state in the same cycle as the first control step.

[0162] Furthermore, in the first control step, the frequency of LF may be, for example, 0.1 Hz to 100 Hz. Furthermore, the duty ratio of the bias power (= fourth state / (third state+fourth state)) may be in the range of 1% to 90%.

[0163] Fig. 13CIn the control method of the modification 5-3, in addition to the first control step which is the same as the modification 5-1, the control of the source power of the second control step of the modification 5-1 and the control of the bias power of the third control step of the modification 5-2 are further performed. That is, the state in which both the source power and the bias power are intermittently stopped in the modification 5-3 is an example of the fourth state.

[0164] The period in which the bias power is intermittently stopped and the period in which the generated source power is intermittently stopped may be synchronized. In this case, the period in which the generated source power and the bias power are intermittently stopped may be synchronized as follows: Fig. 13C As shown, it can also be Fig.13D The generated source power is shown to be staggered backwards than the bias power, but it can also be staggered forwards than the bias power. The stop time of the generated source power can be longer or shorter than the stop time of the bias power.

[0165] [Effects of the control methods of Modifications 5-1 to 5-4]

[0166] As described above, in the control methods of Modifications 5-1 to 5-4, the quality and quantity of free radicals and ions can be controlled. Specifically, when HF is turned off, the ions in the plasma are almost completely eliminated, but the life of free radicals is relatively long, so they do not disappear but exist for a certain period of time. Thus, for example, during the period when HF is turned off, the free radicals can be uniformly diffused. In addition, during the period when HF is controlled to be turned off or at a low level, the ratio of ions to free radicals in the plasma can be changed. Thus, the quantity of free radicals and ions can be controlled.

[0167] In addition, when the gas is dissociated, free radicals corresponding to the progress of the dissociation are generated. For example, C4F8 gas is dissociated according to C4F8→C4F7*→····→CF2, and different free radicals (C4F7*, etc.) are generated according to the degree of dissociation. As parameters for the progress of dissociation, there are ion energy and reaction time. Therefore, by controlling the bias power, the application period of the source power, and the application time to control the ion energy and / or reaction time, it is possible to promote the generation of free radicals suitable for the treatment and control the quality of free radicals and ions.

[0168] In addition, during the period when the bias power is turned off, etching does not progress due to the reduction of ion energy, and byproducts deposited at the bottom of the hole or the like can be removed outside the hole and deposited on the mask. In addition, during the period when the bias power is turned off, free radicals can be attached to the pattern surface on the wafer W. Thus, the free radicals attached to the mask protect the mask, and the mask selectivity can be improved. Therefore, etching can be promoted, the etching rate can be increased, and the etching shape can be made good.

[0169] The above describes an example of the effect of stopping the power of the generating source intermittently, but the invention is not limited thereto. For example, there is a case where plasma can be generated by using bias power, and there is a case where the same effect can be obtained by stopping the bias power intermittently. That is, by stopping the bias power intermittently, the quality and quantity of free radicals and ions can be controlled. Thus, the etching rate can be increased and the etching shape can be improved.

[0170] In addition, FIG. 13A to FIG. 13D In the third state, the source power is turned on during the period when the LF Vdc is deeply negative, but the present invention is not limited thereto, and the source power may be turned on during the period when the LF Vdc is positive or during other periods. In addition, instead of periodically turning the source power on and off, the source power may be periodically controlled to be high and low.

[0171] [Variation 6]

[0172] Below, refer to Fig.14 , a control method of a variation example 6 of an embodiment is described. Fig.14 It is a timing chart showing a control method according to a sixth variation of an embodiment.

[0173] For example, in the control method of variation 6, Fig.14 As shown, a LF pulse is applied to the stage 16. The positive value of the LF pulse coincides with the positive peak value of the LF voltage, and the negative value of the LF pulse coincides with the negative peak value of the LF voltage.

[0174] In this case, in the control method of Modification 6, the first state and the second state of HF are applied alternately in synchronization with the phase within one cycle of the LF pulse. This makes it possible to control the quantity and quality of radicals and ions.

[0175] Specifically, the power of the generating source may be controlled to be off or low level in part or all of the period when the LF pulse is positive, and the power of the generating source may be controlled to be on or high level in part or all of the period when the LF pulse is negative. In this way, the LF pulse is binary-valued, and the power of the generating source is controlled in binary-valued manner accordingly, so that the control becomes easy. In addition, Fig.14 In, with Fig.13A The LF voltage pulse obtained by pulsing the LF pulse correspondingly controls Fig.13A The HF state shown in FIG. 1 is not limited to this. For example, Figures 13B to 13D The LF voltage is pulsed to obtain the LF pulse corresponding to the control Figures 13B to 13D The status of HF is shown.

[0176] [Variation 7-1 to Variation 7-4]

[0177] Below, refer to Figures 15A to 15D , a control method of variant examples 7-1 to 7-4 of one embodiment is described. Fig.15A It is a timing chart showing a control method according to a variation 7-1 of one embodiment. Fig. 15B It is a timing chart showing a control method of a variation 7-2 of an embodiment. Fig. 15C It is a timing chart showing a control method of a variation 7-3 of an embodiment. Fig.15D It is a timing chart showing a control method of a variation 7-4 of an embodiment.

[0178] exist Fig.15A and Fig. 15B In the control method of the modification 7-1 and modification 7-2 shown, in the first control step, the first state and the second state of the source power are alternately applied in synchronization with the phase within one cycle of the reference electrical state taking the LF voltage or the electrode potential as an example. In modification 7-1, the first state of the source power has two or more states in a stepwise manner in synchronization with the period when the electrode potential is negative. In addition, in modification 7-2, the first state of the source power has two or more states smoothly in synchronization with the period when the electrode potential is negative. However, the first state of the source power may also be synchronized with the period when the electrode potential is positive.

[0179] exist Fig. 15C and Fig.15D In the control method of the modification 7-3 and modification 7-4 shown, in addition to the first control step, there is also a second control step, in which the first state and the second state of the source power are alternately applied in synchronization with the phase within one cycle of the reference electrical state taking the LF voltage as an example. In modification 7-3, the first state of the source power has more than two states in a stepwise manner in synchronization with the period when the electrode potential is positive. In addition, in modification 7-4, the first state of the source power has more than two states smoothly in synchronization with the period when the electrode potential is positive. However, the first state of the source power may also be synchronized with the period when the electrode potential is negative.

[0180] In Modifications 7-1 to 7-4, by controlling the power of the generating source in the first state to a plurality of values, the amount and quality of the radicals and ions can be controlled with higher precision. Fig. 15C and Fig.15D In addition to the first control step shown, it is also possible to replace Fig. 15C and Fig.15D The second control step has Fig. 13B The third control step shown can also be replaced by Fig. 15C and Fig.15D The second control step has Fig. 13C and Fig.13D The second control step and the third control step are shown.

[0181] In the control method of variant 3 of one embodiment, the strength of the electromagnet 350 is controlled according to the phase (or impedance) of the reference electrical state, the phase of LF, the electrode potential to which the bias power is applied, LF Vdc or the reflected wave power of HF, etc. Thus, the change in impedance observed from the matching devices 46 and 88 is reduced, and the generation of IMD can be suppressed. In addition, in the control method of variant 4 of one embodiment, the frequency of HF is changed according to the amount of change in the C component caused by the change in the sheath thickness. That is, based on the formula of the supply frequency of f (supply frequency) ∝ 1 / √LC, the frequency f of HF is changed according to the change in the C component corresponding to the thickness of the sheath. Thus, a state in which matching is roughly obtained according to the change in the thickness of the sheath can be achieved, the reflected wave power of HF can be reduced, and the generation of IMD can be suppressed. In addition, in variant 4, the second high-frequency power supply 90 uses a frequency variable power supply that can change the frequency of HF.

[0182] The variable frequency power supply is controlled so that the frequency is continuously changed when the load impedance is constant, and the reflected wave power of the generated source power becomes very small. However, when the generated source power is controlled synchronously with the phase of the voltage or current of the LF within one cycle, the load of the HF changes greatly periodically within one cycle of the voltage or current of the LF. Therefore, the second high frequency power supply 90 needs to change the frequency according to the sheath thickness, which changes greatly periodically according to the phase of the LF within one cycle, and more preferably according to the impedance corresponding to the sheath thickness.

[0183] For example, Fig.16 : is a diagram showing an example of HF reflected wave power (HF-Pr) according to one embodiment. HF reflected wave power varies depending on the type of gas and the phase of LF. For example, Fig.16 (a) shows an example of HF reflected wave power (see B) when argon gas is supplied into the processing container 10, 500 W of HF traveling wave power (HF-Pf) is applied (see A), and 1000 W of LF power is applied. Fig.16 (b) shows an example of HF reflected wave power (see B) when SF6 gas is supplied into the processing container 10, HF traveling wave power of 500W is applied (see A), and LF power of 1000W is applied. In addition, C shows the potential of the wafer mounted on the mounting table 16. The potential of the wafer is substantially equal to the LF voltage Vpp when the LF frequency is, for example, 400kHz, and the amplitude (amplitude) of the HF voltage Vpp when the HF frequency is, for example, 100MHz is added, and the wafer vibrates at the potentials of both.

[0184] observe Fig.16 As can be seen from B in (a) and (b), the distribution of the reflected wave power of HF with respect to the phase within one cycle of LF is different between the case where argon gas is supplied and the case where SF6 gas is supplied.

[0185] Regarding the process of changing the output frequency of HF output from the second high-frequency power supply 90 to the most appropriate frequency in real time according to the difference in the distribution of the reflected wave power of HF, it is not realistic because it takes time for the second high-frequency power supply 90 to determine the most appropriate frequency. For example, an ordinary variable frequency power supply can measure the reflected wave power by shifting the frequency at a maximum of 1kHz to 10kHz. On the other hand, for example, for a 400kHz LF, when one cycle is divided into 10, it becomes 4MHz, and the wavelength is shifted 10 times within the divided parts. For this purpose, it is necessary to change the wavelength by 40MHz, and synchronously determine the reflected amount of HF and the direction of change of the frequency in real time. This operation cannot be performed at the operating frequency of an ordinary variable frequency power supply, and is not realistic.

[0186] Therefore, in the control method of variant examples 8 to 11 of one embodiment, when the reflected wave power of HF is controlled synchronously with the phase within one cycle of the reference electrical state (the phase of LF in this variant), the frequency with less reflection of HF is obtained in each phase obtained by dividing one cycle of LF, and the reflected wave power of HF is suppressed to a minimum. In variant examples 8 to 11, each phase of LF represents each phase when one cycle of LF is divided into 10 at least. However, the number of divisions of one cycle of LF is not limited to this, and it can also be any one of 10 divisions to 100 divisions. The more the number of divisions of the phase of one cycle of LF is, the higher the control accuracy is, and the reflected wave power of HF can be further reduced. The control of variant examples 8 to 11 is performed by the processor 100.

[0187] [Variation 8]

[0188] First, refer to Fig.17 , a control method of a variant example 8 of an embodiment is described. Fig.17 This is a timing diagram for explaining a control method of a modified example 8 of an embodiment. In the control method of the modified example 8 of an embodiment, the frequency of HF is changed synchronously with each phase obtained by dividing one cycle of LF into a plurality of phases. Moreover, the reflected wave power of HF at this time is monitored, and the frequency of HF of the second high-frequency power supply 90 is controlled according to the monitoring result so that the reflected wave power of HF at each phase becomes smaller. Then, before processing and during processing, a process of finding a new frequency of HF output from the second high-frequency power supply 90 is implemented at a prescribed time, and based on the result, the frequency of HF controlled by the second high-frequency power supply 90 is determined.

[0189] Fig.17 The horizontal axis represents time, the left side of the vertical axis represents the HF traveling wave power (HF-Pf) and the reflected wave power (HF-Pr), and the right side of the vertical axis represents the chip potential.

[0190] exist Fig.17 In the first cycle of , it shows the reflected wave power of HF when the frequency controlled by the second high frequency power supply 90 is set to the initial frequency in the first cycle of LF (the first cycle of C) (refer to B). The initial frequency is an arbitrary value, for example, it is set to a basic frequency (for example, 40MHz).

[0191] exist Fig.17 In the second cycle of LF (the second cycle of C), the frequency controlled by the second high-frequency power supply 90 is changed from the initial frequency to another frequency. However, in the second cycle, the frequency is not reduced for each phase corresponding to the number of divisions in the phase of the cycle of LF, but is set to either increase or decrease the frequency, and the relationship between the reflection amount and the phase is obtained. Fig.17 In the second example, an example of increasing the frequency (second frequency) is given, but it can also be reduced.

[0192] The result is that Fig.17 The power of the second reflected wave of HF shown by the solid line B is sometimes reduced and sometimes increased compared to the power of the first reflected wave of HF shown by the dotted line B, depending on the phase. Fig.17 There is a time period in which the reflected wave power of HF decreases when LF is in a positive phase and increases when LF is in a negative phase. However, the reflected wave power at this time is only an example and is not limited to this.

[0193] exist Fig.17 In the third cycle of LF, the shift direction and amount of the frequency controlled by the second high-frequency power source 90 in the third cycle of LF are determined based on the increase or decrease in the reflected wave power of HF in each phase in the previous cycle. Fig.17 The third frequency shown is an example of the determined shift direction and shift amount. In addition, the reflected wave power at this time is only an example and is not limited to this.

[0194] The frequency shift amount and the initial shift direction (the direction of the arrow of the third frequency) temporarily controlled by the second high-frequency power supply 90 can be determined based on past data. The frequency shift amount and the initial shift direction controlled based on past data can be set in advance according to a plan, or can be controlled based on a plan. The past data can be the reflected wave power of the last HF, the reflected wave power of the HF the day before, or the reflected wave power of the HF the day before. For example, based on the state of the last reflected wave power, the frequency shift direction and the shift amount of each phase obtained by dividing one cycle of the next LF can be determined, so that for each phase obtained by dividing one cycle of LF, the reflected wave power of the HF of each phase is reduced. The shift direction and the shift amount can also be determined based on the state of the reflected wave power of the last time, or instead of the state of the reflected wave power of the last time, based on the state of the reflected wave power of the past before the last time.

[0195] The frequency of the third control of the second high frequency power source 90 is shifted in the direction of reducing reflections. However, in this control period, when one cycle of LF is divided into 10, for example, the frequency is changed at a time interval obtained by dividing one cycle of LF into 10.

[0196] After the fourth time, the second high frequency power supply 90 oscillates the HF at the optimal frequency based on the data of the third time or the data obtained before that. The frequency controlled by the second high frequency power supply 90 is repeated within the range of the allowable frequency until a predetermined number of times is reached or the reflected wave power of the HF reaches a predetermined specified amount, thereby reducing the frequency at which the reflected wave power of the HF is small in each phase of one cycle of the LF.

[0197] In the control method of variation 8 of one embodiment, the above-described process is performed at a specified period. As a result, the reflected wave power of HF that changes due to the phase of LF and the type of gas can be reduced as much as possible. In addition, as an example of the specified period, the synchronization pulse period of the time interval when dividing one period n (n≧10) of LF, the time specified in the processing scheme, the predetermined time interval, etc. can be cited.

[0198] [Variation 9]

[0199] Below, refer to Fig.18 , a control method of a variation example 9 of an embodiment is described. Fig.18 1 is a timing chart for explaining a control method of a variation example 9 of an embodiment. In the control method of variation example 9 of an embodiment, similarly to variation example 8, the second high frequency power source 90 controls the value of the generated source power output by the second high frequency power source 90 in addition to controlling the frequency of HF synchronously with each phase within one cycle of LF.

[0200] For example Fig.18 As shown, in the time period near B1 where the reflected wave power of HF is small, the second high frequency power source 90 controls the frequency of HF (refer to Fig.17 ), and the output of the HF power (generated source power) shown in D increases as shown in D1. On the contrary, in the time period B2 when the reflected wave power of HF is large, the second high frequency power supply 90 changes the frequency of HF, and reduces the output of the generated source power as shown in D2.

[0201] In the control method of variation 9 of one embodiment, the reflected wave power of HF that changes due to the phase of LF and the type of gas can be reduced as much as possible, and when the reflected wave power of HF is small, the reduction in plasma density can be suppressed by increasing the source power. In addition, when LF is in a positive phase, the source power can be controlled within the range of the first source power to the second source power, and when LF is in a negative phase, the source power can be controlled within the range of the third source power to the fourth source power. The range of the first source power to the second source power and the range of the third source power to the fourth source power can be different ranges or the same range, and the range of one can be included in the range of the other or partially overlap.

[0202] [Variation 10]

[0203] Below, refer to Fig.19 , a control method of a variation 10 of an embodiment is described. Fig.19 This is a timing chart for explaining a control method according to a tenth modification of an embodiment.

[0204] Fig.19 The horizontal axis represents an example of one cycle of LF and one cycle of RF pulse. One cycle of RF pulse can be 0.1 to 100 kHz, can be longer or shorter than this, but is set to a time period longer than one cycle of LF. In the control method of variation 10 of one embodiment, the second high-frequency power supply 90 can, for example, control the frequency of HF in accordance with each phase obtained by dividing the phase of one cycle of RF pulse into a plurality of phases. The frequency of HF and the generated source power can also be controlled in accordance with each phase obtained by dividing the phase of one cycle of RF pulse into a plurality of phases.

[0205] In particular, immediately after the RF pulse is turned on and off, the plasma density Ne and the electrode potential change greatly, and the reflected wave power of HF tends to change differently from when the RF pulse is stable. Fig.19As shown, after the moment V when the RF pulse is turned on in each cycle, the rise of LF takes time and the sheath thickness is thin (that is, the capacitance of the sheath is large). Therefore, after the moment V when the RF pulse is turned on, the second high frequency power supply 90 controls the frequency of HF to be higher (see E).

[0206] in addition, Fig.19 In the second half of the RF pulse, the bias power is turned off (see C1). During this period, the reflected wave power of HF is close to 0 and constant as shown in B3. That is, during the period when the bias power is turned off and the generating source power is turned on, the impedance of the sheath is always constant because the bias power is turned off. Therefore, the reflected wave power of HF becomes constant. Therefore, during the period when the bias power is turned off, the frequency is determined so that the reflected wave power of HF becomes the minimum, and the second high-frequency power supply 90 outputs the generating source power of the determined frequency.

[0207] During the period when the bias power is turned off, the generated source power can be controlled to be turned off or on. Fig.19 As shown in C1, during the period when the bias power is turned off, the frequency of HF is set to frequency E1 in the first half, and the generated source power is controlled to a high level (or turned on), and the frequency of HF is changed to frequency E2 in the second half, and the generated source power is controlled to a low level (or turned off). In addition, the period of intermittently stopping the generated source power and the bias power can be consistent, or the generated source power can be staggered backward compared to the bias power, or the generated source power can be staggered forward compared to the bias power. The stop time of the generated source power can be longer or shorter than the stop time of the bias power.

[0208] In addition, the control method of Modification 8 to Modification 10 is as follows: Figure 2A The processor 100 executes and sends a control signal for controlling the frequency and power of HF to the second high frequency power source 90 via the signal generating circuit 102. The second high frequency power source 90 changes the frequency and power of HF to be output according to the control signal.

[0209] [Variation 11]

[0210] Below, refer to Fig. 20 , a control method of a variant example 11 of an embodiment is described. Fig. 20 This is a timing chart for explaining a control method according to Modification 11 of one embodiment.

[0211] As described in Modification 10, immediately after the RF pulse is turned on, the rise of LF takes time and the sheath thickness is thin (ie, the sheath capacitance is large). Therefore, during the rise of the RF pulse, the plasma density Ne changes greatly, and the impedance changes greatly.

[0212] Therefore, in the control method of Modification 11, the second high frequency power source 90 is in the period of RF pulse rise in one cycle of LF, that is, Fig. 20 The E3 makes a synthesized wave of multiple frequencies oscillate. Figure 2A The reflection detector 111 detects the reflected wave power of HF corresponding to each of the plurality of frequencies. The detected reflected wave power of HF of each frequency is sent to the processor 100.

[0213] For example, when the second high frequency power source 90 can increase the frequency to 35 MHz to 45 MHz, the synthetic wave of five frequencies of 41, 42, 43, 44, and 45 MHz is oscillated. Here, the reflection detector 111 detects the reflected wave power corresponding to the generated source power of each of the five frequencies and sends it to the processor 100. The processor 100 selects the frequency with the least reflected wave power.

[0214] For example, when the frequency with the least reflected wave power is 41 MHz, the frequency is determined to be 41 MHz during the period when the RF pulse rises in one cycle of the next LF, which can be the frequency of the HF output from the second high frequency power supply 90. Fig. 20 In E4, for example, the generated source powers of five frequencies, namely 39, 40, 41, 42, and 43 MHz, can be output with the frequency of 41 MHz, where the power of the last reflected wave is the least, as the center.

[0215] Thus, the frequency of HF outputted from the second high frequency power source 90 can be made to reach the target frequency with the least HF reflected wave power as soon as possible. As a result, the generated source power outputted from the second high frequency power source 90 can have the frequency with less HF reflected wave power earlier, and the plasma can be ignited earlier.

[0216] In addition, when the processor 100 executes the control method of the modification example 11, based on Figure 2A The reflected wave powers of HF corresponding to the plurality of frequencies detected by the reflection detector 111 are transmitted to the second high frequency power source 90 via the signal generating circuit 102 as a control signal for controlling the frequency of HF.

[0217] However, the present invention is not limited thereto, and the second high frequency power source 90 may also have the function of the processor 100. In this case, the reflected wave powers of HF corresponding to a plurality of frequencies detected by the reflection detector 111 are directly transmitted from the reflection detector 111 to the second high frequency power source 90.

[0218] In this case, the second high frequency power supply 90 can be implemented as a variable frequency power supply including a control unit having the function of the processor 100. That is, in this case, the control unit of the variable frequency power supply obtains the reflected wave power of the HF corresponding to each of the frequencies of the plurality of HFs from the reflection detector 111, and selects the frequency with the least reflected wave power based on the obtained reflected wave power of the HF. Then, the control unit determines to output the generated source power of the selected frequency from the variable frequency power supply. The variable frequency power supply changes the frequency of the generated source power to the determined frequency and outputs it at a specified power. Thus, the second high frequency power supply 90 can control the frequency and generated source power of the HF to be output without using the processor 100 and the signal generating circuit 102. Thus, the second high frequency power supply 90 can execute the control methods of variants 8 to 11 without using the processor 100.

[0219] In the control method of modification 11, a high frequency synthesized by multiple frequencies is used, but a high frequency synthesized by multiple frequencies can also be used in the control methods of modifications 8 to 10. In addition, in the control methods of modifications 8 to 10, the mixing ratio of the high frequencies of multiple frequencies can be freely changed, or there can be a process for optimizing it.

[0220] The control method of variant examples 8 to 11 described above is a control method for a plasma processing device having a first electrode for carrying a processed body, which includes: a step of supplying bias power to the above-mentioned first electrode; and a step of supplying a generated source power having a frequency higher than the above-mentioned bias power to a plasma processing space, the above-mentioned generated source power having a first state and a second state, and the above-mentioned control method includes a first control step, which controls the above-mentioned first state and the above-mentioned second state to more than two frequencies in accordance with each phase when the phase within one cycle of a reference electrical state is divided into multiple phases, wherein the reference electrical state represents a signal synchronized with the cycle of the high frequency of the above-mentioned bias power, or any one of the voltage, current or electromagnetic field measured by the power supply system of the above-mentioned bias power.

[0221] [Variation 12]

[0222] In Modification 12, the first state of the HF voltage takes a pulsed voltage value that repeats two or more voltage values. Fig.21 In the example of , the first state of the HF voltage repeats the positive voltage value and the voltage value 0. However, this is not limited to this, and the voltage value may be repeated for example, three voltage values, or two or more voltage values.

[0223] [Variation 13]

[0224] The bias power may be a power of a sine waveform or a pulse waveform, or a power of a tailored waveform. That is, the bias voltage or current may be a sine waveform, or a LF pulse waveform, or a Fig. 22 The custom waveform shown. In the custom waveform, Fig. 22 The HF shown can modulate the bias power when it is in the second state, and can also modulate the bias power when it is in the first state.

[0225] In addition, similarly, when the first state of HF takes two or more voltage values, the waveform of HF has Figures 15A to 15D , Fig.21 In addition to the waveform shown, Fig. 22 Custom waveform shown.

[0226] The plasma processing device and control method of one embodiment disclosed in the present invention are illustrative in all aspects and should not be considered as restrictive. The above-mentioned embodiments can be deformed and improved in various ways without departing from the scope and gist of the attached claims. Other structures can be added to the contents described in the above-mentioned multiple embodiments within the scope of non-contradiction. In addition, the contents described in the above-mentioned multiple embodiments can be combined within the scope of non-contradiction.

[0227] The plasma processing device of the present invention can also be applied to any type of device including Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP).

[0228] For example, a control method for a plasma processing device, wherein the plasma processing device includes a first electrode for carrying a processed object and a second electrode opposite to the first electrode, the control method for the plasma processing device includes: a step of supplying bias power to the first electrode; and a step of supplying a generated source power having a frequency higher than the bias power to a plasma processing space, the generated source power having a first state and a second state, the control method includes a first control step, the first control step alternately applying the first state and the second state in synchronization with the phase within a cycle of the reference electrical state.

[0229] A control method for a plasma processing device having a first electrode for carrying a processed object, comprising: a step of supplying bias power to the first electrode; and a step of supplying a generated source power having a frequency higher than the bias power to a plasma processing space, wherein the generated source power has a first state and a second state, and the control method comprises a first control step of alternately applying the first state and the second state in synchronization with the phase within a cycle of the reference electrical state.

[0230] The step of supplying source power having a frequency higher than the bias power to the plasma processing space may be performed by supplying source power such as microwave energy or high-frequency electric energy to the plasma processing space through a plasma generating source for generating plasma.

[0231] In this specification, a wafer W is described as an example of a processed object. However, the substrate is not limited thereto, and may be various substrates used for LCD (Liquid Crystal Display), FPD (Flat Panel Display), CD substrate, printed circuit board, etc.

[0232] This international application claims the priority based on Japanese Patent Application No. 2018-119344 filed on June 22, 2018 and Japanese Patent Application No. 2019-105708 filed on June 5, 2019, the entire contents of which are incorporated herein by reference.

[0233] Description of Reference Numerals

[0234] 1……Plasma treatment device

[0235] 10...Disposal Container

[0236] 16……Placement table (lower electrode)

[0237] 34...Upper electrode

[0238] 47...Power supply pole

[0239] 46……Matcher

[0240] 48...The first high frequency power supply

[0241] 50...Variable DC power supply

[0242] 66...Processing gas supply source

[0243] 84...Exhaust

[0244] 88……Matcher

[0245] 89...Power supply pole

[0246] 90... Second high frequency power supply

[0247] 91...GND module

[0248] 100...Processor

[0249] 102...Signal generating circuit

[0250] 105, 108...Directional coupler

[0251] 111...Reflection detector

[0252] 112……Oscilloscope

[0253] 200……Control Department

[0254] 250...Additional circuit

[0255] 300... Impedance variation circuit

[0256] 350…Electromagnet.

Claims

1. A method for controlling a plasma processing device having a first electrode for carrying a processed object, characterized in that: include: The step of supplying bias power to the first electrode; and a step of supplying a generated source power having a higher frequency than the bias power to the plasma processing space, The generated source power has a first state and a second state, The control method includes a first control step of alternately applying the first state and the second state in phase synchronization with a cycle of a reference electrical state, wherein the reference electrical state represents a signal synchronized with a cycle of the high frequency of the bias power, or any one of a voltage, a current or an electromagnetic field measured by a power supply system of the bias power.

2. The control method according to claim 1, characterized in that: The plasma processing device has a second electrode opposite to the first electrode, The step of supplying the generated source power to the plasma processing space applies the generated source power to the first electrode or the second electrode.

3. The control method according to claim 1 or 2, characterized in that: The period of the first state includes a time when the phase of the reference electrical state reaches a positive peak.

4. The control method according to claim 1 or 2, characterized in that: The period of the first state includes a time when the phase of the reference electrical state reaches a negative peak.

5. The control method according to any one of claims 1 to 4, characterized in that: The first state is greater than the second state.

6. The control method according to any one of claims 1 to 5, characterized in that: A second control step is included of intermittently stopping the generation source power at a cycle that is independent of a cycle of the reference electrical state.

7. The control method according to any one of claims 1 to 6, characterized in that: A third control step is included which causes the bias power to be intermittently stopped at a cycle that is independent of the cycle of the voltage or current of the HF.

8. The control method according to any one of claims 1 to 7, characterized in that: include: a second control step of causing the generation source power to be intermittently stopped at a cycle independent of a cycle of the reference electrical state; and a third control step of causing the bias power to be intermittently stopped at a cycle independent of the cycle of the voltage or current of the HF, The second control step and the third control step are synchronized.

9. The control method according to any one of claims 1 to 8, characterized in that: A pulsed power corresponding to a peak value of the phase of the reference electrical state is applied.

10. The control method according to any one of claims 1 to 9, characterized in that: The first state has two or more states.

11. The control method according to any one of claims 1 to 10, characterized in that: The value of the generated source power in the second state is 0.

12. The control method according to any one of claims 1 to 11, characterized in that: The reference electrical state is a state of a signal synchronized with a high-frequency period of the bias power, or any one of a voltage, a current or an electromagnetic field measured in any component in the bias power supply system from the first electrode to the inside of a matching device connected via a power supply rod of the bias power.

13. A plasma processing device, characterized in that: include: A first electrode for carrying a processed object; a plasma generating source for generating plasma; a bias power supply for supplying bias power to the first electrode; a generation source power supply for supplying a generation source power having a frequency higher than the bias power to the plasma generation source; as well as a control unit for controlling the bias power supply and the generating source power supply, The generated source power has a first state and a second state, The control unit controls to alternately apply the first state and the second state in phase synchronization with one cycle of a reference electrical state, wherein the reference electrical state represents a signal synchronized with a high frequency cycle of the bias power, or any one of a voltage, current or electromagnetic field measured by a power supply system of the bias power.

14. A plasma processing device, characterized in that: include: A first electrode for carrying a processed object; a second electrode opposite to the first electrode; a bias power supply for supplying bias power to the first electrode; a generating source power supply for supplying a generating source power having a frequency higher than the bias power to the first electrode or the second electrode; as well as a control unit for controlling the bias power supply and the generating source power supply, The generated source power has a first state and a second state, The control unit controls to alternately apply the first state and the second state in phase synchronization with one cycle of a reference electrical state, wherein the reference electrical state represents a signal synchronized with a high frequency cycle of the bias power, or any one of a voltage, current or electromagnetic field measured by a power supply system of the bias power.

15. The plasma processing device according to claim 13 or 14, characterized in that: The control unit generates a synchronization signal synchronized with the phase of the reference electrical state, generates a control signal for a generation source power supply that outputs generation source power based on the synchronization signal, and transmits the control signal to the generation source power supply.

16. The plasma processing apparatus according to any one of claims 13 to 15, characterized in that: An additional circuit having at least any one of a coil, a variable capacitor, or a diode is installed on the supply line of the bias power and the generated source power or the first electrode.

17. The plasma processing apparatus according to any one of claims 13 to 16, wherein: An impedance varying circuit having a variable impedance is installed on the bias power and the source power supply line or the first electrode, The control unit changes the impedance of the impedance changing circuit.

18. The plasma processing apparatus according to any one of claims 13 to 17, wherein: having a magnetic field generating unit for applying a magnetic field, The control unit controls the strength of the magnetic field generated by the magnetic field generating unit according to the bias power, the phase of the reference electrical state, the potential of the first electrode to which the bias power is applied, self-bias, or the measured reflected wave power of the generated source power.

19. The plasma processing apparatus according to any one of claims 13 to 18, wherein: The generating source power supply is a variable frequency power supply, The control unit changes the frequency of the generated source power output from the generated source power supply according to the phase of the reference electrical state.

20. A method for controlling a plasma processing device having a first electrode for carrying a processed object, characterized in that: include: The step of supplying bias power to the first electrode; and a step of supplying a generated source power having a higher frequency than the bias power to the plasma processing space, The generated source power has a first state and a second state, The control method includes a first control step, wherein the first control step controls the first state and the second state to two or more frequencies corresponding to each phase when the phase within a cycle of the reference electrical state is divided into multiple phases, wherein the reference electrical state represents a signal synchronized with the high-frequency cycle of the bias power, or any one of the voltage, current or electromagnetic field measured by the power supply system of the bias power.

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