Plasma processing apparatus, processor, control method, non-transitory computer-readable recording medium, and power supply system

Abstract

To control the quantity and quality of radicals and ions.SOLUTION: A plasma processing apparatus includes: a stage; a first radio frequency power supply that supplies a bias waveform oscillating at a first frequency, a cycle of the bias waveform lasting for a predetermined period of time, the bias waveform being applied to the stage; a second radio frequency power supply that supplies a source waveform oscillating at a second frequency higher than the first frequency, the second frequency being variable during the cycle of the bias waveform; and a control unit that controls the second radio frequency power supply to change the second frequency during the cycle of the bias waveform such that a reflected wave power is reduced and to have a period in which the power level of the source waveform is increased.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a plasma processing apparatus, a processor, a control method, a non-transitory computer-readable recording medium, and a power supply system. [Background technology]

[0002] A technique is known in which, during etching, the high-frequency power applied for attracting ions is synchronized with the on / off switching of the high-frequency power for generating plasma to allow ions to reach the polycrystalline silicon layer, thereby making the etching rate of the polycrystalline silicon layer uniform (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-64915 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the etching rate is controlled by applying high frequency powers of two different frequencies into a processing chamber, that is, source power, which is high frequency power for generating plasma, and bias power, which is high frequency power for attracting ions.

[0005] The present disclosure provides techniques for controlling the quantity and quality of radicals and ions. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a plasma processing apparatus having a stage, a first high frequency power supply supplying a bias waveform oscillating at a first frequency, where a cycle of the bias waveform lasts for a predetermined period of time, the bias waveform being applied to the stage, a second high frequency power supply supplying a source waveform oscillating at a second frequency higher than the first frequency, where the second frequency is variable during the cycle of the bias waveform, and a controller controlling the second high frequency power supply to control a power level of the source waveform during the cycle of the bias waveform. Effect of the Invention

[0007] According to one aspect, the quantity and quality of radicals and ions can be controlled. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a plasma processing apparatus according to an embodiment. [Figure 2A] FIG. 4 is a diagram showing an example of the configuration of a control unit according to an embodiment. [Figure 2B] 11A and 11B are diagrams showing a case where control is performed using a phase signal of a sensor attached to a power supply system according to an embodiment, or a case where control is performed using a signal synchronized with the high frequency period of the bias power. [Diagram 3] FIG. 11 is a diagram showing an example of HF supply timing according to a phase within one LF period according to an embodiment. [Figure 4] FIG. 11 is a diagram showing an example of HF supply timing according to a phase within one LF period according to an embodiment. [Diagram 5] FIG. 13 is a diagram showing an example of the relationship between the phase of an LF within one period and the plasma density Ne and the self-bias Vdc according to an embodiment. [Figure 6] FIG. 4 is a diagram showing an example of reflected wave power according to an embodiment. [Figure 7] FIG. 4 is a diagram showing an example of reflected wave power according to an embodiment. [Figure 8] FIG. 11 is a diagram for explaining a control method according to a first modified example of an embodiment. [Figure 9]FIG. 11 is a diagram for explaining a control method according to a second modified example of an embodiment. [Figure 10] FIG. 11 is a diagram for explaining a control method according to a third modified example of an embodiment. [Figure 11] FIG. 11 is a diagram for explaining a control method according to a fourth modified example of an embodiment. [Figure 12] FIG. 2 is a diagram showing an example of IMD (intermodulation distortion) according to an embodiment. [Figure 13A] 13 is a timing chart showing a control method according to Modification 5-1 of the embodiment. [Figure 13B] 13 is a timing chart showing a control method according to Modification 5-2 of the embodiment. [Figure 13C] 13 is a timing chart showing a control method according to Modification 5-3 of the embodiment. [Figure 13D] 13 is a timing chart showing a control method according to Modification 5-4 of the embodiment. [Figure 14] 13 is a timing chart showing a control method according to a sixth modified example of the embodiment. [Figure 15A] 13 is a timing chart showing a control method according to Modification 7-1 of the embodiment. [Figure 15B] 13 is a timing chart showing a control method according to Modification 7-2 of the embodiment. [Figure 15C] 13 is a timing chart showing a control method according to Modification 7-3 of an embodiment. [Figure 15D] 13 is a timing chart showing a control method according to Modification 7-4 of the embodiment. [Figure 16] FIG. 4 is a diagram showing an example of reflected wave power of source power according to an embodiment. [Figure 17] 13 is a timing chart for explaining a control method according to Modification 8 of the embodiment. [Figure 18] 13 is a timing chart for explaining a control method according to a ninth modified example of the embodiment. [Figure 19] 13 is a timing chart for explaining a control method according to a tenth modification of the embodiment. [Figure 20]13 is a timing chart for explaining a control method according to the eleventh modification of the embodiment. [Figure 21] 23 is a timing chart showing a control method according to a twelfth modification of the embodiment. [Figure 22] 23 is a timing chart showing a control method according to a thirteenth modification of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components are designated by the same reference numerals, and redundant description will be omitted.

[0010] Hereinafter, the frequency (high frequency) of the source power is also referred to as "HF" (High Frequency), and the source power is also referred to as "HF power." Also, the frequency (high frequency) of the bias power, which is lower than the frequency of the source power, is also referred to as "LF" (Low Frequency), and the bias power is also referred to as "LF power."

[0011] [Introduction] When two different frequency radio frequency powers, that is, source power for generating plasma and bias power for attracting ions, are applied to a processing chamber, IMD (Intermodulation Distortion) may occur as reflected wave power.

[0012] IMD not only causes mismatching, but also requires a high-frequency power source with a capacity capable of inputting a higher-frequency power than is actually required in order to resist reflections and maintain the plasma. For this reason, the cable length of the coaxial cable used in the power supply line of the high-frequency power source has traditionally been optimized to reduce the occurrence of IMD.

[0013] However, IMD occurs at the frequency of the sum or difference between the fundamental wave and / or harmonics of the HF power and the fundamental wave and / or harmonics of the LF power. Therefore, the method of optimizing the cable length of the coaxial cable can reduce the reflected wave power of high frequency power of a specific frequency, but cannot eliminate the reflected wave power of other frequencies that are generated from the sum or difference between the fundamental wave and / or harmonics of the HF power and the LF power included in the IMD.

[0014] In addition, the lower the frequency of the LF power, the closer the IMD occurs to the fundamental frequency of the HF power, so it is possible to increase the frequency of the LF power as much as possible to suppress the occurrence of IMD at frequencies close to the fundamental frequency of the HF power. However, in recent years, particularly in etching processes with high aspect ratios, the lower the frequency of the LF power, the better the process results. In other words, the deeper the hole with a high aspect ratio is etched, the lower the etching rate becomes, so the frequency of the LF power is made lower and the power is increased. This makes it possible to increase the etching rate in etching with a high aspect ratio. However, this process condition further increases IMD, so the reflected wave power of the high frequency power has become higher due to the recent trend toward higher power and lower frequency of the LF power. In particular, the reflected wave power of the high frequency power increases when LF power and HF power are applied to the same electrode.

[0015] For example, Figure 12 shows an example of the reflected wave power generated when HF power of a specified frequency is applied to an electrode to which LF power has also been applied. The intensity of IMD changes periodically in synchronization with the phase of the LF Vpp (Peak to Peak). For example, in the example of Figure 12, when the LF potential is near the maximum positive value, the IMD is almost 0 W, meaning that no reflection occurs. Also, when the LF potential is in the negative range, the IMD is relatively low. When the LF potential exceeds the maximum positive value and then turns negative, the maximum reflected wave power occurs and the IMD is at its maximum.

[0016] Therefore, the inventors propose a control method for suppressing the occurrence of IMD according to the phase of LF, taking into consideration the timing of the occurrence of IMD, and a plasma processing apparatus for executing the control method. Furthermore, the inventors propose a control method for controlling the quantity and quality of radicals and ions by controlling high frequency powers of two different frequencies, LF and HF.

[0017] [Overall configuration of plasma processing device] First, an example of a plasma processing apparatus 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of a plasma processing apparatus according to an embodiment.

[0018] The plasma processing apparatus 1 according to one embodiment is a capacitively coupled parallel plate plasma processing apparatus, and includes a cylindrical processing vessel 10 made of, for example, aluminum whose surface is anodized. The processing vessel 10 is grounded.

[0019] A cylindrical support table 14 is disposed on the bottom of the processing vessel 10 via an insulating plate 12 made of ceramics or the like, and a mounting table 16 made of, for example, aluminum is provided on the support table 14. The mounting table 16 constitutes a lower electrode, and a wafer W, which is an example of an object to be processed, is mounted on the mounting table 16 via an electrostatic chuck 18.

[0020] An electrostatic chuck 18 that attracts and holds 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. A DC power supply 22 is connected to the electrode 20. A DC voltage output from the DC power supply 22 is applied to the electrode 20. The wafer W is attracted and held by the electrostatic chuck 18 by the electrostatic force such as a Coulomb force generated thereby.

[0021] A conductive edge ring 24 made of, for example, silicon is disposed on the mounting table 16 around the wafer W. The edge ring 24 is also called a focus ring. A cylindrical inner wall member 26 made of, for example, quartz is provided on the side surfaces of the mounting table 16 and the support table 14.

[0022] A coolant chamber 28 is provided inside the support table 14, for example, in a ring shape. A coolant, for example, cooling water, at a predetermined temperature is circulated and supplied to the coolant chamber 28 from an externally provided chiller unit via pipes 30a, 30b, and the processing temperature of the wafer W on the mounting table 16 is controlled by the temperature of the coolant. Note that the coolant is an example of a temperature adjustment medium circulated and supplied to the pipes 30a, 30b, and the temperature adjustment medium may not only cool the mounting table 16 and the wafer W, but may also heat them.

[0023] Furthermore, a heat transfer gas, for example, He gas, is supplied from a heat transfer gas supply mechanism to between the upper surface of the electrostatic chuck 18 and the rear surface of the wafer W via a gas supply line 32 .

[0024] 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 faces the wafer W on the mounting table 16 and forms a surface in contact with the plasma processing space, i.e., a facing surface.

[0025] The upper electrode 34 is supported on the upper part of the processing chamber 10 via an insulating shielding member 42. The upper electrode 34 includes an electrode plate 36 that forms a surface facing the mounting table 16 and has a number of gas discharge holes 37, and an electrode support 38 that detachably supports the electrode plate 36 and is made of a conductive material, for example, aluminum whose surface has been anodized. The electrode plate 36 may be made of, for example, silicon or SiC. A gas diffusion chamber 40 is provided inside the electrode support 38, and a number of gas flow holes 41 that communicate with the gas discharge holes 37 extend downward from the gas diffusion chamber 40.

[0026] The electrode support 38 is formed with a gas inlet 62 for introducing a processing gas into the gas diffusion chamber 40. 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 opening / closing valve 70 are provided in the gas supply pipe 64, in this order from the upstream side. Processing gas for etching is supplied from the processing gas supply source 66. The processing gas flows from the gas supply pipe 64 to the gas diffusion chamber 40, and is discharged from the gas discharge holes 37 in a shower-like manner into the plasma processing space via the gas flow holes 41. In this way, the upper electrode 34 functions as a shower head for supplying the processing gas.

[0027] A variable DC power supply 50 is connected to the upper electrode 34, and a DC voltage from the variable DC power supply 50 is applied to the upper electrode 34. The polarity, current, and voltage of the variable DC power supply 50, and the control of the electronic switches that turn the current and voltage on and off are controlled by a control unit 200.

[0028] A first high frequency power supply 48 is connected to the mounting table 16 via a power feed rod 47 and a matching device 46. The first high frequency power supply 48 applies LF power to the mounting table 16. This causes ions to be attracted to the wafer W on the mounting table 16. The first high frequency power supply 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 supply 48 with the load impedance.

[0029] A second high frequency power supply 90 is connected to the mounting table 16 via a power feed rod 89 and a matching device 88. The second high frequency power supply 90 applies HF power to the mounting table 16. The HF frequency is higher than the LF frequency, and the second high frequency power supply 90 outputs HF power with a frequency of 13.56 MHz or more. For example, HF power with a higher frequency of 100 MHz may be outputted in comparison with LF power of 400 kHz. The matching device 88 matches the internal impedance of the second high frequency power supply 90 with the load impedance. A filter 94 for passing a predetermined high frequency to the ground may be connected to the mounting table 16. The HF power supplied from the second high frequency power supply 90 may be applied to the upper electrode 34.

[0030] An exhaust port 80 is provided at the bottom of the processing vessel 10, and an exhaust device 84 is connected to the exhaust port 80 via an exhaust pipe 82. The exhaust device 84 has a vacuum pump such as a turbo molecular pump, and the inside of the processing vessel 10 can be depressurized to a desired vacuum level. A transfer port 85 for the wafer W is provided at the side wall of the processing vessel 10, and the transfer port 85 can be opened and closed by a gate valve 86. A deposit shield 11 is detachably provided along the inner wall of the processing vessel 10 to prevent etching by-products (deposits) from adhering to the processing vessel 10. That is, the deposit shield 11 constitutes the wall of the processing vessel. The deposit shield 11 is also provided on the outer periphery of the inner wall member 26. An exhaust plate 83 is provided between the deposit shield 11 on the wall side of the processing vessel at the bottom of the processing vessel 10 and the deposit shield 11 on the inner wall member 26 side. The deposit shield 11 and the exhaust plate 83 are made of an aluminum material such as Y. 2 O 3 For example, a ceramic-coated ceramic material such as fluorine may be used.

[0031] When performing an etching process in the plasma processing apparatus 1 having such a configuration, first, the gate valve 86 is opened, and the wafer W to be etched is loaded into the processing chamber 10 through the loading / unloading port 85 and placed on the mounting table 16. Then, a processing gas for etching is supplied from the processing gas supply source 66 to the gas diffusion chamber 40 at a predetermined flow rate, and is supplied into the processing chamber 10 through the gas flow hole 41 and the gas discharge hole 37. The processing chamber 10 is then evacuated by the exhaust device 84, and the pressure therein is set to a set value within a range of, for example, 0.1 to 150 Pa. Here, various conventionally used processing gases can be used, for example, C 4 F 8 Gases containing halogen elements such as Ar gas and O 2 Other gases such as gas may also be included.

[0032] With the etching gas introduced into the processing vessel 10 in this manner, HF power is applied to the mounting table 16 from the second high frequency power supply 90. Also, LF power is applied to the mounting table 16 from the first high frequency power supply 48. Also, a DC voltage is applied to the upper electrode 34 from the variable DC power supply 50. Also, a DC voltage is applied to the electrode 20 from the DC power supply 22, and the wafer W is attracted and held on the mounting table 16.

[0033] The processing gas discharged from the gas discharge holes 37 of the upper electrode 34 is dissociated and ionized mainly by the HF power to generate plasma. The surface to be processed of the wafer W is etched by radicals and ions in the plasma. In addition, by applying LF power to the mounting table 16, the ions in the plasma can be controlled, making it possible to etch holes with a high aspect ratio, and the plasma control margin can be widened.

[0034] The plasma processing apparatus 1 is provided with a control unit 200 that controls the operation of the entire apparatus. The control unit 200 executes a desired plasma process such as etching according to a recipe stored in a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The recipe includes control information for the apparatus with respect to process conditions, such as process time, pressure (exhaust of gas), high frequency power and voltage, various gas flow rates, temperature inside the processing vessel (upper electrode temperature, side wall temperature of the processing vessel, wafer W temperature, electrostatic chuck temperature, etc.), and temperature of the coolant output from the chiller. Note that these programs and recipes indicating the processing conditions may be stored in a hard disk or a semiconductor memory. Also, the recipe may be set at a predetermined position while being stored in a portable computer-readable storage medium such as a CD-ROM or DVD, and read out.

[0035] The on / off or high / low of the HF power may be controlled to be synchronized with a signal synchronized with the high frequency cycle of the bias power, or with the phase within one cycle of the voltage, current, or electromagnetic field measured in the bias power supply system. For example, the control unit 200 may control the on / off or high / low of the HF power to be synchronized with the phase within one cycle of the LF voltage or current. This makes it possible to control the quantity and quality of ions and radicals. Also, the occurrence of IMD can be reduced.

[0036] The bias power feed system refers to the first high frequency power supply 48 → matching box 46 → power feed rod 47 → mounting table 16 → (plasma) → upper electrode 34 → (ground). Either the voltage, current or electromagnetic field measured in the bias power feed system refers to the voltage, current or electromagnetic field measured in the parts from the first high frequency power supply 48 to the mounting table 16 via the inside of the matching box 46 and the power feed rod 47, and in the upper electrode 34.

[0037] In addition, the state of a signal synchronized with the high frequency period of the bias power, or any of the voltage, current, or electromagnetic field measured in the bias power power supply system is also called the “reference electrical state.” The HF power (source power) is controlled so as to be applied alternately between a first state and a second state, which will be described later, in synchronization with the phase within one period of the reference electrical state.

[0038] However, when any of the voltage, current, or electromagnetic field measured in the bias power supply system is taken as the “reference electrical state”, it is preferable that the reference electrical state is any of the voltage, current, or electromagnetic field measured in any component from the mounting table 16 to the inside of the matching unit connected via the power supply rod 47.

[0039] One example of a method for measuring the reference electrical state in a bias power supply system is to measure the voltage, current, or induced magnetic field of each part by placing a voltage probe, a current probe, or a BZ probe (a probe that measures an induced magnetic field) near one of the parts in the bias power supply system.

[0040] For example, Fig. 2B(a) shows an example in which any one of the voltage, current, or electromagnetic field measured in the bias power supply system is set as the "reference electrical state". For example, in Fig. 2B(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 attached to the power supply system. The processor 100 applies the source power alternately between the first state and the second state in synchronization with the phase within one period of the reference electrical state indicating any one of the input HF voltage or current, the LF voltage or current, the HF phase signal, or the LF phase signal.

[0041] The processor 100 may generate a signal synchronized with the high frequency period of the bias power output from the first high frequency power supply 48, not based on a signal from the sensor. In this case, the state of the signal can be set as the reference electrical state. Also, the step of measuring the reference electrical state in the bias power supply system can be omitted. For example, in FIG. 2B(b), the processor 100 inputs an LF phase signal (low power waveform) or a signal related to information on the bias power from the first high frequency power supply 48, and generates a signal synchronized with the high frequency period of the bias power based on this input signal. The processor 100 outputs the generated signal to the second high frequency power supply 90. The second high frequency power supply 90 applies the source power alternately between the first state and the second state based on this signal.

[0042] The processor 100 may generate a signal synchronized with the high frequency period of the bias power, not based on the signal from the first high frequency power supply 48. In this case, the processor 100 generates a signal having a period, for example, as shown in LF in FIG. 3, and generates an on / off signal, for example, as shown in HF in FIG. 3, synchronized with this signal. 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 the bias power based on this signal. The second high frequency power supply 90 applies the source power alternately between the first state and the second state based on this signal.

[0043] 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 facing the first electrode. The first high frequency power supply 48 is an example of a bias power supply that supplies LF power to the first electrode. The second high frequency power supply 90 is an example of a source power supply that supplies HF power with a higher frequency than the LF power to the first electrode or the second electrode. The control unit 200 is an example of a control unit that controls the bias power supply and the 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 electrode potential.

[0044] [Control Unit Configuration] 2A, a specific configuration of the control unit 200 will be described. The control unit 200 includes a processor 100, a signal generating circuit 102, directional couplers 105 and 108, a reflection detector 111, and an oscilloscope 112.

[0045] A directional coupler 105 is connected to the power supply line of the first high frequency power supply 48 between the first high frequency power supply 48 and the matching box 46. A directional coupler 108 is connected to the power supply line of the second high frequency power supply 90 between the second high frequency power supply 90 and the matching box 88.

[0046] The directional coupler 105 provides a portion of the LF forward wave power (Pf) to the oscilloscope 112. In addition, the directional coupler 108 provides the oscilloscope 112 with a portion of the HF forward wave power and reflected wave power.

[0047] In one embodiment, the LF frequency displayed on the oscilloscope 112 is, for example, 400 kHz, and the HF frequency is, for example, 100 MHz. This allows the oscilloscope 112 to observe the waveform of the LF forward wave power, the waveform of the HF forward wave power, and the waveform of the HF reflected wave power.

[0048] Further, the directional coupler 108 separates a certain percentage of the reflected HF wave and provides it to a reflection detector 111. The reflection detector 111 is composed of, for example, a spectrum analyzer, a power meter, etc., and measures the amount of IMD (Intermodulation Distortion) occurring at what wavelength and how much of it is occurring and the reflected wave power. IMD refers to the reflected wave power from the plasma side that is generated according to the frequency of the sum or difference between the LF fundamental wave and / or harmonics and the HF fundamental wave and / or harmonics, which is generated by applying HF power to the upper electrode or lower electrode (lower electrode in one embodiment) of the plasma processing apparatus 1 and applying LF power to the lower electrode.

[0049] The directional coupler 105 provides a portion of the LF traveling wave power to the processor 100. The processor 100 creates a synchronization signal for HF that is synchronized with the LF traveling wave power. For example, the processor 100 may create a synchronization signal for HF in synchronization with the positive timing of the LF traveling wave. Note that instead of the directional coupler 105, an LF waveform detected using a sensor such as a VI probe may be provided to the processor 100.

[0050] The processor 100 provides the created synchronization signal to a signal generating circuit 102. The signal generating circuit 102 generates a control signal synchronized with the LF traveling wave power from the provided synchronization signal, and provides the control signal to the second high frequency power supply 90 and the first high frequency power supply 48.

[0051] There are two methods for generating the control signal. When the first high frequency power supply 48 is a general power supply, the directional coupler 105 extracts part of the LF voltage or current 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 the above, and the processor 100 may input part of the LF power or the like directly from the first high frequency power supply 48. The processor 100 creates an ON signal having an arbitrary delay and an arbitrary width from the input waveform signal and transmits it to the signal generating circuit 102. The ON signal is an example of a synchronization signal.

[0052] The signal generating circuit 102 sends a command signal to the second high frequency power supply 90 to generate HF power during the on signal. Depending on the input form of the second high frequency power supply 90, the command signal may be a control signal for generating HF power during the on signal or the on signal itself.

[0053] When the first high frequency power supply 48 is an amplifier that amplifies LF power, voltage, or current, the signal from the directional coupler 105 is not used, and the signal generating circuit 102 may extract a part of the LF power or the like output from the first high frequency power supply 48 as a waveform, and create an ON signal having an arbitrary delay and an arbitrary width from 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 supply 90.

[0054] However, the above method of generating the control signal is merely an example and is not limiting. As long as a control signal can be generated from a given synchronization signal to control the HF power to be turned on and off or to be alternately applied between high and low 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.), other hardware or software can be used, without being limited to the circuit of the control unit 200 shown in FIG. 2A.

[0055] The amplifier of the first high frequency power supply 48 amplifies the amplitude of the 400 kHz LF modulation signal (AM) and supplies it to the lower electrode. The amplifier of the second high frequency power supply 90 amplifies the amplitude of the 100 MHz HF modulation signal and supplies it to the lower electrode.

[0056] 3 is a diagram showing an example of an LF voltage or current waveform and an HF voltage or current applied in response to the timing when the LF voltage or current is positive. When the electrode potential shown in the second waveform from the bottom is positive, the HF voltage or current is controlled to a positive value (ON). When the electrode potential is negative, the HF voltage or current is controlled to 0 (OFF). Basically, since the electrode potential is determined by the LF voltage or current, the HF voltage or current is turned off when the LF voltage or current is negative, and is turned on when the LF voltage or current is positive.

[0057] The processor 100 may generate a synchronization signal that controls the HF power during a time period that includes the timing when the electrode potential is positive. However, the processor 100 is not limited to this, and may generate a synchronization signal that controls the HF power during a short period that includes the timing when the electrode potential is most negative.

[0058] [HF power supply timing] Next, the supply timing of HF power in one embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of the supply timing of HF power in one embodiment.

[0059] The vertical axis in Figures 4(a) to (c) indicates the electrode potential. The electrode potential is almost the same as the wafer potential. The electrode potential is the potential when the LF and HF voltages are superimposed. Here, the Vpp of the LF voltage when the LF frequency is 400 kHz is much greater than the Vpp of the HF voltage when the HF frequency is 100 MHz. Therefore, basically, the electrode potential is determined by the LF voltage, and oscillates with the width (amplitude) of the Vpp of the HF voltage.

[0060] The thickness of the sheath on the electrode is also basically determined by the LF voltage. When the LF voltage is negative, the electrode potential becomes more negative than when the LF voltage is positive, due to the so-called self-bias voltage Vdc. When the electrode potential is positive with respect to the ground potential, it becomes close to the plasma potential, allowing some high-speed electrons to flow into the electrode, and when it is negative with respect to the ground potential, ions flow in.

[0061] Since the electrode is floated from the ground by a blocking capacitor (a matching device in one embodiment), electrons that flow into the electrode do not flow to the ground. Therefore, electrons flow into the electrode and accumulate during a period (half cycle) when the surface of the electrode is at a positive potential with respect to the plasma. However, due to the accumulated electrons, the surface of the electrode becomes negatively charged, generating a negative bias with respect to the plasma. This negative bias causes ions to flow into the surface of the electrode. This forms a sheath on the surface of the electrode.

[0062] Ultimately, the surface of the electrode approaches the plasma potential, and the DC component of the electrode potential when the inflowing electrons and the steadily inflowing ions due to the negative bias are in equilibrium is the self-bias voltage Vdc.

[0063] 3 shows a schematic diagram of the electrode potential corresponding to the LF phase, the plasma potential corresponding to the LF phase, the sheath thickness, and the impedance Z. The plasma potential is slightly higher than the highest potential in the processing vessel 10. Therefore, when the electrode potential is positive, the plasma potential is slightly higher than the electrode potential, and when the electrode potential is negative, the plasma potential is slightly higher than the potential 0 of the wall surface, assuming that the potential of the wall of the processing vessel 10 is 0.

[0064] When the LF voltage is negative due to the self-bias voltage Vdc, the electrode potential becomes deeper toward the negative side, and the sheath thickness becomes thicker because the sheath thickness is proportional to the voltage. On the other hand, when the electrode potential is positive, a smaller voltage is applied to the electrode than when the electrode potential is negative, and the sheath thickness becomes thinner.

[0065] In one embodiment, since LF power and HF power are applied to the mounting table 16 (lower electrode), the electrode potential shown in FIG. 4 is the potential of the lower electrode. The thickness of the sheath on the mounting table 16 has a timing when it is almost flat and thin, and a timing when it is thick, corresponding to the phase of the LF. For this reason, if the sheath is assumed to be a capacitor, when the sheath is thin, the capacitance of the capacitor becomes large, and the impedance Z of the sheath becomes lower than impedance Z=1 / ωC. In other words, when the electrode potential is positive, the impedance Z is low and almost constant because the sheath is thin. On the other hand, when the electrode potential is negative, the impedance Z is high and changes greatly because the sheath is thick. Furthermore, the impedance Z is almost determined by the LF voltage. From the above, impedance matching of the HF power becomes difficult. In particular, when the electrode potential is negative, that is, when the LF voltage is negative, the impedance is high and changes greatly, so impedance matching of the HF power becomes difficult.

[0066] In response to such fluctuations in impedance Z, the matching device 88 that performs impedance matching for HF power can track up to a maximum frequency of about 1 Hz due to the operation of the motor, but at frequencies higher than this, it becomes difficult to track and match, and matching is performed at one timing of the impedance that changes moment by moment depending on the phase of the LF. In this state, the matching device 88 cannot match at phases other than the one timing at which it matches, so the reflected wave power of the IMD is large.

[0067] Therefore, in one embodiment, as shown in Figures 4(a) and 4(b), the HF power is controlled to be on or high when the electrode potential is positive, and the HF power is controlled to be off or low when the electrode potential is negative.

[0068] In one embodiment, when the electrode potential is positive, the impedance Z is almost constant, so matching is easy to achieve by supplying HF power at this timing. For this reason, the HF power is controlled to ON or High at this timing. On the other hand, when the electrode potential is negative, the impedance is high and changes greatly, so matching is difficult to achieve even if HF power is supplied at this timing. For this reason, the supply of HF power is controlled to OFF or Low at this timing. This makes it possible to reduce the occurrence of IMD.

[0069] As shown in Fig. 4(b), when the HF power is controlled to High or Low, the HF power is not turned off but is kept low when the electrode potential is negative, so that the decrease in plasma density can be suppressed compared to when the HF power is controlled to On or Off. In addition, the occurrence of IMD can be suppressed by making the HF power applied when the electrode potential is negative smaller than the HF power applied when the electrode potential is positive.

[0070] However, the control method of turning on or high the HF power by matching it with the timing when the electrode potential is positive is an example, and is not limited thereto. The HF power may be controlled to be on or high when at least a part of the phase of the reference electrical state is positive. Also, the HF power may be controlled to be on or high when at least a part of the phase of the reference electrical state is negative. That is, the HF power (source power) has a first state and a second state smaller than the first state, and the period of the first state may include a timing when the phase of the reference electrical state is at a peak. In this case, the peak may be a positive peak or a negative peak. Also, the period of the first state may include a timing when at least a part of the phase of the reference electrical state is positive. Also, the period of the first state may include a timing when at least a part of the phase of the reference electrical state is negative. Also, the HF power may be applied not only as a rectangular wave matched with the timing when the phase of the reference electrical state is positive, but also as a substantially rectangular wave including at least one of a rising slow-up or a falling slow-down. Furthermore, the HF power may be applied at least either at a timing shifted a predetermined time later than or a predetermined time earlier than the timing when the phase of the reference electrical state is positive.

[0071] The following is an example of the use of the control method of shifting the HF power by a predetermined time from the timing when the phase of the reference electrical state is positive. If HF power is applied only when the phase of the reference electrical state is positive, the ion energy will be small. Depending on the type of etching, a process with a larger ion energy may be desired. In that case, HF power is applied until the timing when the LF reference electrical state goes from positive to negative and the desired amount of ion energy is obtained. This makes it possible to realize a process with a large ion energy.

[0072] Also, the duration of the supply of HF power may be adjusted so as to shorten or lengthen the HF power by a predetermined time with respect to the timing when the phase of the reference electrical state is positive. For example, the HF power may be supplied not only at the timing when the phase of the reference electrical state is positive, but also before and after that, with a predetermined time added.

[0073] HF power may be supplied when the phase of the reference electrical state is negative. However, when the phase of the reference electrical state is negative, the impedance is high and changes with time. Therefore, in this case, it is preferable to control the HF power to be turned on for a shorter time width when the phase of the reference electrical state is negative. For example, it is preferable to adjust the timing and width of the application of HF power using a circuit having a gate function or a delay function. The reflection intensity in one period of the reference electrical state may be measured in advance, and based on the measurement results, a circuit having an automatic adjustment function may be used to control the application of HF power at a timing when there is little reflection of LF power.

[0074] For example, as shown in FIG. 4(c), when the electrode potential is negative, the HF power may be turned on or high for a short time period including the time when the electrode self-bias Vdc is most negative, and the HF power may be turned off or low during other time periods. Also, the reflected wave power may be detected in advance, and depending on the magnitude of the detected power, the HF power may be turned off or low during time periods when the reflected wave power is high, and turned on or high during time periods when the reflected wave power is low. By applying the HF power for a short time period including the time when the electrode potential is most negative as shown in FIG. 4(c), strong ion implantation can be achieved in specific etching such as HARC (High Aspect Ratio Contact). This can improve the etching speed and the etching shape.

[0075] As described above, according to the control method of the plasma processing apparatus 1 of the embodiment, the HF power is controlled to be on / off or high / low in synchronization with the phase within one period of the reference electrical state. This makes it possible to reduce the occurrence of IMD. In addition, it becomes possible to control the ion energy and the quantity and quality of radicals and ions.

[0076] As shown in FIG. 3 and FIG. 4(a) to FIG. 4(c), the state in which the HF power is controlled to ON or HIGH is an example of the first state, and the state in which the HF power is controlled to OFF or LOW is an example of the second state.

[0077] The control method for the plasma processing apparatus 1 according to the embodiment includes a first control step of alternately applying a first state and a second state in synchronization with a phase within one period of a reference electrical state. The second state only needs to be lower than the first state, and the power of the second state may be 0 or may be a value other than 0 that is lower than the first state.

[0078] [Example of effect] Next, an example of the effect of controlling the HF power on / off or high / low in synchronization with the phase within one cycle of the reference electrical state will be described with reference to Fig. 5 to Fig. 7. The graph in Fig. 5 is a diagram showing an example of the relationship between the LF phase, plasma density Ne, and absolute value of self-bias |Vdc| according to one embodiment. Figs. 6 and 7 are diagrams showing an example of reflected wave power according to one embodiment.

[0079] The graph in Figure 5 shows the actual measurement results obtained by periodically applying HF power with a phase change for a time width of about 40% of one cycle of the reference electrical state. The vertical axis on the left of the graph shows the plasma density Ne (cm -3 ), and the absolute value of the self-bias |Vdc| (V) is shown on the right vertical axis. When HF power and LF power are superimposed and applied to the lower electrode of the plasma processing apparatus 1, the sheath of the lower electrode fluctuates with the LF period, and as a result, the impedance Z changes, causing the plasma density Ne and the self-bias Vdc to fluctuate.

[0080] When the HF power is turned on when the electrode potential is positive and turned off when the electrode potential is negative (see the upper left diagram in Fig. 5), the plasma density Ne is high, and the plasma generation efficiency can be increased, as shown in region a in the lower graph in Fig. 5. Also, in region a, the absolute value of the self-bias |Vdc| is low, and the occurrence of IMD can be effectively suppressed.

[0081] Furthermore, if the HF power is turned off when the electrode potential is positive and then turned on for a short period of time including when the electrode potential is most negative (see the upper right diagram in Fig. 5), the plasma density Ne will be medium to high, and the plasma generation efficiency will be medium or higher, as shown in region b in the lower graph in Fig. 5. This is because when the electrode potential is negative, a large voltage is applied to the electrode, the sheath becomes thicker, the HF electric field decreases when the HF power is turned on, and the plasma generation efficiency decreases.

[0082] Furthermore, in region b, the absolute value of the self-bias |Vdc| is high, and the ion energy can be monochromatized, that is, ions with uniform ion energy can be attracted to the wafer W. Particularly in a high aspect ratio process, monochromatized high-energy ions can be attracted to the wafer W. At this time, the occurrence of IMD increases, but by applying HF power for a short period of time when the potential of the lower electrode becomes most negative, the occurrence of IMD can be reduced overall compared to the case of applying HF power all the time.

[0083] As described above, according to the plasma processing apparatus 1 of one embodiment, the occurrence of IMD can be reduced by controlling the HF power to ON or High based on the timing when the electrode potential is positive, for example. In addition, the plasma generation efficiency can be improved by applying the HF power when the electrode potential is positive, since the sheath becomes thicker when the electrode potential is negative, which is an issue in that the plasma generation efficiency decreases.

[0084] Moreover, monochromatic high-energy ions can be attracted to the wafer W by applying HF power for a short period of time when the electrode potential is negative and at its deepest potential.

[0085] For example, the upper and lower graphs on the left side of Fig. 6 and the waveforms on the screens in (a) and (b) on the right side of Fig. 6 show an example of the detection results by the reflection detector 111 of the control unit 200 and the display results of the oscilloscope 112. The graph on the lower left shows Vpp and Vdc in one LF cycle. The deeper Vdc is negative, the thicker the sheath becomes, and the lower the plasma generation efficiency when HF power is applied. The graph on the upper side shows the HF forward wave power (Pf) and reflected wave power (Pr) versus Vpp and Vdc in one LF cycle.

[0086] An example of the display of oscilloscope 112 in Fig. 6(a) shows waveform A of LF forward wave power measured when the LF phase shown in area c is 180°, and amplitude B of high frequency power on the wafer (i.e., the combined value of LF power and HF power). Also, the waveform of the HF forward wave power is shown in C, and the waveform of the HF reflected wave power is shown in D. Also, an example of the display of oscilloscope 112 in Fig. 6(b) shows waveform A of LF forward wave power measured when the LF phase shown in area d is 0° (=360°), amplitude B of the high frequency power on the wafer, waveform C of HF forward wave power, and waveform D of HF reflected wave power.

[0087] According to this, the reflected wave power is smaller in the region d than in the region c. Therefore, it can be seen that the occurrence of IMD can be suppressed by alternately applying the HF power to a first state (e.g., on or high state) and a second state (e.g., off or low state) in synchronization with a signal synchronized with the cycle of the high frequency of the bias power so that the phase of the LF includes 0°, or in synchronization with the phase within one cycle of the reference electrical state measured in the power supply system of the bias power. For example, as described above, by setting the HF power to the first state in accordance with the timing when the electrode potential is positive and setting the HF power to the second state in accordance with the timing when the electrode potential is negative, control according to the absolute value |Vdc| of the self-bias can be performed to suppress IMD and increase the plasma generation efficiency. In addition, by controlling the HF power to the first state and the second state at any timing according to the electrode potential, high energy ions can be attracted to the wafer W by utilizing the region where the plasma density Ne is high and the region where the absolute value |Vdc| of the self-bias is large. In addition, in this case, the occurrence of IMD can be reduced overall by applying the HF power in a pulsed manner.

[0088] FIG. 7 shows an example of LF Vpp, LF |Vdc|, HF forward wave power (Pf), and HF reflected wave power (Pr). According to this, the HF reflected wave power (Pr) changes up to about 5 times (about 10W to about 50W) in the phase of one cycle of the LF voltage. From the above, it is possible to reduce IMD to about 1 / 5 by controlling the HF power in synchronization with the phase in one cycle of the reference electrical state. It is also found that the LF Vpp and LF |Vdc| can be changed within a range of up to about 1.6 times the minimum value by controlling the HF power in synchronization with the phase in one cycle of the reference electrical state.

[0089] [Variations] Next, control methods according to Modifications 1 to 4 of an embodiment will be described with reference to Figs. 8 to 11. Fig. 8 is a diagram for explaining a control method according to Modification 1 of an embodiment. Fig. 9 is a diagram for explaining a control method according to Modification 2 of an embodiment. Fig. 10 is a diagram for explaining a control method according to Modification 3 of an embodiment. Fig. 11 is a diagram for explaining a control method according to Modification 4 of an embodiment.

[0090] (Variation 1) In the embodiment described above, if it is desired to pulse modulate the HF power in synchronization with the phase within one period of the reference electrical state (see HF AM modulation in FIG. 3), an HF power supply that pulse modulates at the same frequency as the LF frequency is required, which may increase costs.

[0091] 8(a), in the plasma processing apparatus 1 according to the first modification, an additional circuit 250 constituting a bypass line is attached to 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, a coil 252 and a variable capacitor 251 are connected in series to a power supply rod connected to the lower electrode, and the variable capacitor 251 is connected to the processing vessel 10 and grounded.

[0092] By making the ratio of the impedance on the processing vessel 10 side to the load impedance on the plasma side appear larger by the additional circuit 250, even if the impedance changes compared to when the additional circuit 250 is not present, the additional circuit 250 can mitigate a large change in the impedance Z obtained by combining the impedances on the additional circuit 250 and the processing vessel 10 side. For example, as shown in FIG. 8(b), the additional circuit 250 reduces the change in the combined impedance Z, so that the occurrence of IMD can be further suppressed when HF power is applied in synchronization with the phase within one period of the reference electrical state. In addition, by simply installing the additional circuit 250, a mechanism for suppressing IMD can be constructed simply and inexpensively. Note that, when the additional circuit 250 is inserted on the second high frequency power source 90 side after the branching of the power feed rod, the HF power is less susceptible to the influence of the LF power, which is preferable. If a filter is provided between the first high frequency power source 48 and the second high frequency power source 90, the HF power is further less susceptible to the influence of the LF power, the fluctuation of the combined impedance Z can be reduced, and the occurrence of IMD can be further suppressed. The additional circuit 250 may include at least one of an element of a coil, a capacitor, or a diode.

[0093] (Variation 2) In the plasma processing apparatus 1 according to the second modification, as shown in FIG. 9(a), an impedance change circuit 300 is attached to a power supply line or a lower electrode connected to a first high frequency power supply 48 and a second high frequency power supply 90. The impedance change circuit 300 functions to change the impedance so that a composite impedance of the load impedance on the plasma side and the impedance of the impedance change circuit 300 becomes constant. Alternatively, the impedance change circuit 300 changes the impedance according to the phase of the LF so as to suppress a change in the impedance seen from the matching device 88. This suppresses the reflected wave power and reduces the occurrence of IMD. The impedance change circuit 300 changes the impedance within one period of the reference electrical state according to the phase (or impedance) of the LF, the Vdc or the reflected wave power of the LF, etc., thereby suppressing IMD.

[0094] An example of the impedance change circuit 300 is a configuration in which capacitors are provided in an array and connections of the capacitors are switched by electronic switches. The control unit 200 controls the electronic switches to change the impedance of the impedance change circuit 300.

[0095] 9(b), the control unit 200 switches the connection of the capacitor of the impedance change circuit 300 so as to reduce the change in the combined impedance Z of the load impedance on the plasma side and the impedance of the impedance change circuit 300. This improves impedance matching and further suppresses the occurrence of IMD when HF power is applied in synchronization with the phase within one cycle of the reference electrical state.

[0096] The impedance change circuit 300 may be inserted inside the matching unit 88 and integrated with the matching unit 88. It is preferable that the impedance change circuit 300 is inserted on the second high frequency power source 90 side after the power feed rod branches, because the HF power is less susceptible to the influence of the LF power. If a filter is provided between the first high frequency power source 48 and the second high frequency power source 90, the HF power is further less susceptible to the influence of the LF power, the fluctuation of the combined impedance Z can be reduced, and the occurrence of IMD can be further suppressed.

[0097] (Variation 3) In the third modification, as shown in FIG. 10(a), an electromagnet 350 is provided on the upper part of the processing vessel 10. The position of the electromagnet 350 is not limited to the position shown in FIG. 10(a) and may be any part of the processing vessel 10, for example, inside the processing vessel 10. The control unit 200 changes the characteristics of the magnetic field by controlling the strength of the electromagnet 350 according to the phase (or impedance) of the reference electric state, the phase of the LF, the electrode potential to which the bias power is applied, the LF Vdc or the reflected wave power of the HF, and the like. For example, as shown in FIG. 10(b), when the LF Vdc at which the sheath becomes thick is negative, the magnetic field is strengthened, and when the LF Vdc at which the sheath becomes thin is positive, the magnetic field is weakened or eliminated to reduce the change in impedance Z. This can further suppress the occurrence of IMD. The electromagnet 350 may be 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 by the electromagnet 350 shown in the third modification may be used in combination with the control by the additional circuit 250 of the first modification or the impedance changing circuit 300 of the second modification.

[0098] (Variation 4) When the thickness of the sheath changes, the apparent capacitance changes, and the HF resonance frequency changes. The matching device 88 functions to sum all L components and C components of the inductance (e.g., the power supply rod, etc.) and conductance (e.g., the sheath, etc.) in the processing vessel 10 to resonate at the HF frequency and achieve matching.

[0099] Therefore, if the sheath thickness changes, the C component changes, and so the reflected wave power would increase unless the matching device 88 re-matches the C component in response to the change in the sheath thickness. However, since it takes about one second for the matching device 88 to move the variable capacitor, it may not be able to follow the change in the sheath thickness and may not be able to match accurately.

[0100] Therefore, in the fourth modification, the control unit 200 changes the HF frequency by the change in the C component caused by the change in the sheath thickness. That is, based on the supply frequency equation f(supply frequency) ∝ 1 / √LC, the HF frequency f is changed according to the change in the C component caused by the sheath thickness.

[0101] For example, if the capacitance of the sheath on the electrode is assumed to be C, and the capacitance C changes by a factor of four in response to the change in the sheath thickness, the HF frequency will change by a factor of about two, which will provide a roughly matched state in response to the change in the sheath thickness.

[0102] Moreover, when the capacitance C changes tenfold in response to the change in the sheath thickness, the HF frequency is changed by about 3.3 times. This allows the frequency to be roughly matched in response to the change in the sheath thickness. That is, in the fourth modification, as shown in FIG. 11(a), the HF frequency is changed based on the above-mentioned equation for the resonance frequency so as to match the change in the sheath thickness in response to the change in one cycle of the LF voltage. This allows the frequency to be roughly matched in response to the change in the sheath thickness, and the reflected wave power of the HF can be reduced, thereby suppressing the occurrence of IMD. In the fourth modification, the second high-frequency power supply 90 uses a variable frequency power supply capable of changing the HF frequency. The control shown in the fourth modification may be used in combination with at least one of the additional circuit 250 in the first modification, the impedance change circuit 300 in the second modification, or the electromagnet 350 in the third modification.

[0103] Furthermore, for all the examples of the above embodiments and modified examples, the shift time or delay width may be adjusted by a circuit having a gate function or a delay function based on any of the original signals or measurement signals, such as the LF phase, electrode potential, power supply system potential, Vdc, electrode sheath thickness, plasma light emission, and HF power reflection intensity.

[0104] Also, instead of controlling the timing of applying the HF power in synchronization with the phase within one cycle of the LF voltage, as shown in FIG. 11(b), it is possible to apply pulsed power (hereinafter also referred to as "LF pulse") corresponding to the peak of the LF voltage, and control the timing of applying the HF power in response to the LF pulse. That is, for example, an LF pulse corresponding to a 400 kHz LF may be applied by turning it on and off, and the HF power may be controlled in pulsed form (HF pulse) in response to this. It is also possible to apply LF pulse power corresponding to the peak of the phase of the reference electrical state, and control the timing of applying the HF power in response to the LF pulse.

[0105] As described above, the intensity of IMD generation varies depending on the LF power. Therefore, according to the control method of the plasma processing apparatus 1 according to the above embodiment and each of the above modifications, the generation of IMD can be reduced by selecting a timing when the HF reflected wave power is low and applying the HF power at that timing. By reducing the generation of IMD, the stability of the process and the plasma processing apparatus 1 can be improved, and the cost of the apparatus can be reduced. Furthermore, it is possible to control the plasma density, the self-bias Vdc, and the like.

[0106] However, if the time for applying HF power is reduced, there is a concern that the absolute amount of HF power will decrease, resulting in a lower plasma density Ne. Therefore, LF power and HF power may be applied at each of two timings including the time when the reference electrical state reaches a peak twice in one cycle. In addition, the method of controlling the application of HF power can be freely changed. Note that the application of HF power is not limited to the lower electrode, and may be the upper electrode.

[0107] [Control method] As described above, the control method of the parallel plate plasma processing apparatus 1 according to one embodiment includes a step of supplying bias power to a lower electrode on which a wafer W is placed, and a step of supplying source power having a higher frequency than the bias power to a plasma processing space by applying the source power having a first state and a second state to the lower electrode or the upper electrode. In the control method, the control method includes a first control step of alternately applying the source power having a first state and a second state in synchronization with a signal synchronized with a high frequency period of the bias power, or with a phase within one period of a reference electrical state indicating any one of a voltage, a current, or an electromagnetic field measured in a bias power supply system.

[0108] The above control method can also be performed by a plasma processing apparatus other than the parallel plate type plasma processing apparatus. The control method for the plasma processing apparatus other than the parallel plate type plasma processing apparatus includes a step of supplying a bias power to the lower electrode and a step of supplying a source power having a frequency higher than that of the bias power to the plasma processing space. The control method also includes a first control step in which the source power has a first state and a second state, and the first state and the second state are alternately applied in synchronization with the phase within one period of the reference electrical state.

[0109] [Variations 5-1 to 5-4] Next, a control method of the plasma processing apparatus 1 according to Modifications 5-1 to 5-4 of an embodiment will be described. In Modifications 5-1 to 5-4, the source power and / or the bias power is intermittently stopped. Figures 13A to 13D are timing charts showing the control method according to Modifications 5-1 to 5-4 of an embodiment.

[0110] 13A includes, in addition to the first control step, a second control step of intermittently stopping the source power at a cycle independent of the cycle of the reference electrical state, as shown by way of example, the LF voltage. The first control step and the second control step are repeatedly executed.

[0111] In the modification 5-1, the LF voltage is applied in the same cycle in the first control step and the second control step, while the source power alternates between the first state and the second state at least once in the first control step, and is intermittently stopped between the first control steps in the second control step.

[0112] In the first and second control steps, the LF frequency may be, for example, 0.1 Hz to 100 Hz. The source power duty ratio (=fourth state / (third state+fourth state)) may be within a range of 1% to 90%.

[0113] The state of the source power synchronized with the period of the reference electrical state in the first control step is an example of a third state. The state of the source power independent of the period of the reference electrical state in the second control step is an example of a fourth state different from the third state.

[0114] The control method according to the modification 5-2 of Fig. 13B includes, in addition to the first control step as in the modification 5-1, a third control step of intermittently stopping the bias power at a cycle 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.

[0115] In the modification 5-2, the first control step and the third control step are repeatedly executed. In the modification 5-2, the source power in the third control step is alternately switched between the first state and the second state in the same cycle as the first control step.

[0116] In the first control step, the LF frequency may be, for example, 0.1 Hz to 100 Hz. The duty ratio of the bias power (=fourth state / (third state+fourth state)) may be within a range of 1% to 90%.

[0117] 13C, in addition to the first control step as in Modification 5-1, the control method of Modification 5-3 performs source power control in the second control step of Modification 5-1 and bias power control in the third control step of Modification 5-2. In other words, the state in Modification 5-3 where both the source power and the bias power are intermittently stopped is an example of the fourth state.

[0118] The period during which the bias power is intermittently stopped and the period during which the source power is intermittently stopped may be synchronized. In this case, the periods during which the source power and the bias power are intermittently stopped may be the same as shown in Fig. 13C, or the source power may be shifted behind the bias power or the source power may be shifted ahead of the bias power as shown in Fig. 13D. The stop time of the source power may be longer or shorter than the stop time of the bias power.

[0119] [Effects of the control methods according to the modified examples 5-1 to 5-4] As described above, the control methods according to Modifications 5-1 to 5-4 can control the quality and quantity of radicals and ions. Specifically, when HF is turned off, most of the ions in the plasma are annihilated, but radicals have a long life span and therefore exist for a certain period of time without being annihilated. Therefore, for example, while HF is turned off, the radicals can be uniformly diffused. Also, while HF is controlled to be off or low, the ratio of ions to radicals in the plasma can be changed. This allows the amount of radicals and ions to be controlled.

[0120] In addition, as the gas dissociates, radicals are generated according to the progress of dissociation. For example, C 4 F 8 Gas is C 4 F 8 →C 4 F 7 * →···→CF 2 Depending on the degree of dissociation, different radicals (C 4 F 7 *The parameters that advance the dissociation include ion energy and reaction time. Therefore, by controlling the application timing and application time of the bias power and source power, the ion energy and / or reaction time can be controlled, and the quality of the radicals and ions can be controlled by promoting the generation of radicals suitable for the process.

[0121] Furthermore, while the bias power is off, the ion energy is reduced and etching does not proceed, so by-products deposited at the bottom of holes etc. can be removed outside the holes and deposited on the mask. Furthermore, while the bias power is off, radicals can be attached to the pattern surface on the wafer W. As a result, the radicals attached to the mask protect the mask and the mask selectivity can be improved. This promotes etching, increases the etching rate, and improves the etching shape.

[0122] An example of the effect of intermittently stopping the source power has been described above, but the effect is not limited to this. For example, plasma may be generated by the bias power, and the same effect may be obtained when the bias power is intermittently stopped. In other words, the quality and quantity of radicals and ions can be controlled by intermittently stopping the bias power. This increases the etching rate and improves the etching shape.

[0123] 13A to 13D, in the third state, the source power is turned on when the LF Vdc is deeply negative, but this is not limiting, and the source power may be turned on when the LF Vdc is positive or at other times. Moreover, instead of turning the source power on and off periodically, it may be controlled to be periodically High and Low.

[0124] [Variation 6] Next, a control method according to the sixth modification of the embodiment will be described with reference to Fig. 14. Fig. 14 is a timing chart showing the control method according to the sixth modification of the embodiment.

[0125] For example, in the control method according to the sixth modification, an LF pulse is applied to the mounting table 16 as shown in Fig. 14. The positive value of the LF pulse coincides with the positive peak of the LF voltage, and the negative value of the LF pulse coincides with the negative peak of the LF voltage.

[0126] In this case, in the control method according to the sixth modification, the first and second HF states are applied alternately in synchronization with the phase within one cycle of the LF pulse, which also makes it possible to control the quantity and quality of radicals and ions.

[0127] Specifically, the source power may be controlled to be off or low during a part or all of the positive period of the LF pulse, and may be controlled to be on or high during a part or all of the negative period of the LF pulse. This makes it easier to control since the LF pulse is binarized and the source power is binarized and controlled accordingly. Note that, although FIG. 14 shows that the HF state shown in FIG. 13A is controlled in response to the LF pulse obtained by pulsing the LF voltage in FIG. 13A, this is not limiting. For example, the HF state shown in FIG. 13B to FIG. 13D may be controlled in response to the LF pulse obtained by pulsing the LF voltage in FIG. 13B to FIG. 13D.

[0128] [Modifications 7-1 to 7-4] Next, control methods according to Modifications 7-1 to 7-4 of an embodiment will be described with reference to Figs. 15A to 15D. Fig. 15A is a timing chart showing a control method according to Modification 7-1 of an embodiment. Fig. 15B is a timing chart showing a control method according to Modification 7-2 of an embodiment. Fig. 15C is a timing chart showing a control method according to Modification 7-3 of an embodiment. Fig. 15D is a timing chart showing a control method according to Modification 7-4 of an embodiment.

[0129] In the control methods according to Modifications 7-1 and 7-2 shown in FIG. 15A and FIG. 15B, in the first control step, the first and second states of the source power are applied alternately in synchronization with the phase within one period of a reference electrical state, for example, an LF voltage or an electrode potential. In Modification 7-1, the first state of the source power has two or more states in a stepped manner in synchronization with the negative timing of the electrode potential. Also, in Modification 7-2, the first state of the source power smoothly has two or more states in synchronization with the negative timing of the electrode potential. However, the first state of the source power may be synchronized with the positive timing of the electrode potential.

[0130] The control methods according to Modifications 7-3 and 7-4 shown in Fig. 15C and Fig. 15D have a second control step in addition to the first control step, and in the first control step, the first state and the second state of the source power are applied alternately in synchronization with the phase within one period of a reference electrical state, for example, an LF voltage. In Modification 7-3, the first state of the source power has two or more states in a stepwise manner in synchronization with the positive timing of the electrode potential. Also, in Modification 7-4, the first state of the source power has two or more states smoothly in synchronization with the positive timing of the electrode potential. However, the first state of the source power may be synchronized with the negative timing of the electrode potential.

[0131] In the modified examples 7-1 to 7-4, the source power in the first state is controlled to a plurality of values, thereby enabling more accurate control of the quantity and quality of radicals and ions. Note that in addition to the first control step shown in Fig. 15C and Fig. 15D, the third control step shown in Fig. 13B may be provided instead of the second control step shown in Fig. 15C and Fig. 15D, or the second and third control steps shown in Fig. 13C and Fig. 13D may be provided.

[0132] In the control method according to the third modification of the embodiment, the strength of the electromagnet 350 is controlled according to the phase (or impedance) of the reference electrical state, the phase of the LF, the electrode potential to which the bias power is applied, the LF Vdc or the reflected wave power of the HF, and the like. This reduces the change in impedance seen from the matching devices 46 and 88, thereby suppressing the occurrence of IMD. In addition, in the control method according to the fourth modification of the embodiment, the frequency of the HF is changed by the change in the C component due to the change in the sheath thickness. That is, based on the equation of the supply frequency f(supply frequency) ∝ 1 / √LC, the frequency f of the HF is changed according to the change in the C component for the sheath thickness. This results in a state where the frequency is roughly matched according to the change in the sheath thickness, and the reflected wave power of the HF can be reduced, thereby suppressing the occurrence of IMD. In addition, in the fourth modification, the second high frequency power source 90 uses a frequency variable power source capable of changing the frequency of the HF.

[0133] When the load impedance is constant, the variable frequency power supply continuously changes the frequency and controls the reflected wave power of the source power to be as small as possible. However, when the source power is controlled in synchronization with the phase within one cycle of the LF voltage or current, the HF load fluctuates greatly and periodically within one cycle of the LF voltage or current. Therefore, the second high frequency power supply 90 needs to change the frequency in response to the sheath thickness, which fluctuates greatly and periodically according to the LF phase within one cycle, or more preferably, the impedance according to the sheath thickness.

[0134] For example, FIG. 16 is a diagram showing an example of HF reflected wave power (HF-Pr) according to one embodiment. The HF reflected wave power varies depending on the gas type and LF phase. For example, FIG. 16(a) shows an example of HF reflected wave power (see B) when argon gas is supplied into the processing vessel 10, 500 W of HF forward wave power (HF-Pf) is applied (see A), and 1000 W of LF power is applied. FIG. 16(b) shows an example of SF 6An example of the HF reflected wave power (see B) is shown when gas is supplied, a HF forward wave power of 500 W is applied (see A), and an LF power of 1000 W is applied. Note that C indicates the potential of the wafer mounted on the mounting table 16. The wafer potential is approximately equal to the LF voltage Vpp when the LF frequency is, for example, 400 kHz, and the width (amplitude) of the HF voltage Vpp when the HF frequency is, for example, 100 MHz is added to it, so that the wafer oscillates between both potentials.

[0135] Looking at Fig. 16(a) and (b)(B), the difference between the case where argon gas was supplied and the case where SF 6 It can be seen that the HF reflected wave power output with respect to the phase within one LF cycle is different when gas is supplied and when gas is not supplied.

[0136] It is not realistic to change the number of HF waves output from the second high frequency power supply 90 to an optimal frequency in real time according to the difference in the output of the reflected wave power of the HF, because it takes time for the second high frequency power supply 90 to determine the optimal frequency. For example, a normal variable frequency power supply can perform the work of shifting the frequency and measuring the reflected wave power at a maximum of 1 kHz to 10 kHz. On the other hand, for example, for a 400 kHz LF, if one period is divided into 10, it becomes 4 MHz, and in order to shift the wavelength 10 times within the division, it is necessary to change the wavelength by 40 MHz and determine the amount of reflection of the HF and the direction of change in frequency in real time in synchronization with this. This work is not realistic because the operating frequency of a normal variable frequency power supply is not enough.

[0137] Therefore, in the control method according to Modifications 8 to 11 of the embodiment, when controlling the reflected HF power in synchronization with the phase within one cycle of the reference electrical state (the phase of the LF in this modification), a frequency with less HF reflection is found in each phase into which one LF cycle is divided, and the reflected HF power is minimized. In Modifications 8 to 11, each LF phase indicates each phase when one LF cycle is divided into at least 10 parts. However, the number of divisions of one LF cycle is not limited to this, and may be any of 10 to 100 parts. The greater the number of divisions of the phase of one LF cycle, the higher the accuracy of control, and the more the reflected HF power can be reduced. The control of Modifications 8 to 11 is executed by the processor 100.

[0138] [Variation 8] First, a control method according to the eighth modification of an embodiment will be described with reference to FIG. 17. FIG. 17 is a timing chart for explaining the control method according to the eighth modification of an embodiment. In the control method according to the eighth modification of an embodiment, the HF frequency is changed in synchronization with each phase obtained by dividing one LF cycle into a plurality of phases. Then, the reflected HF power at that time is monitored, and the HF frequency of the second high frequency power supply 90 is controlled so that the reflected HF power in each phase is reduced based on the monitoring result. Then, a sequence for finding a new HF frequency to be output from the second high frequency power supply 90 is performed at predetermined time intervals before or during the process, and the HF frequency controlled by the second high frequency power supply 90 is determined based on the result.

[0139] The horizontal axis of FIG. 17 indicates time, the left vertical axis indicates HF forward wave power (HF-Pf) and reflected wave power (HF-Pr), and the right vertical axis indicates the wafer potential.

[0140] 17 shows the HF reflected wave power (see B) when the frequency controlled by the second high frequency power supply 90 is set to an initial frequency in the first LF cycle (first cycle of C). The initial frequency is an arbitrary value, and is set to one fundamental frequency (e.g., 40 MHz), for example.

[0141] In the second period in Fig. 17, the frequency controlled by the second high frequency power supply 90 is changed from the initial frequency to another frequency in the second period of the LF (the second period of C). However, in the second period, the frequency is not increased or decreased for each phase according to the number of divisions of the phase of one period of the LF, but is set to either increase or decrease, and the phase dependency result of the reflection amount is obtained. In the second example in Fig. 17, an example in which the frequency (second period frequency) is increased is shown, but it may be decreased.

[0142] As a result, it can be seen that the second HF reflected wave power shown by solid line B in Fig. 17 has some areas where reflection is reduced and some areas where reflection is increased depending on the phase compared to the first HF reflected wave power shown by dashed line B. In Fig. 17, there are time periods where the HF reflected wave power is reduced when the LF is in a positive phase and where the HF reflected wave power is increased when the LF is in a negative phase. However, the reflected wave power at this time is merely an example and is not limited to this.

[0143] In the third period of Fig. 17, the shift direction and shift amount of the frequency controlled by the second high frequency power supply 90 in the third LF period are determined based on the increase or decrease in the reflected wave power of the HF for each previous phase. The third frequency shown in Fig. 17 is an example of the determined shift direction and shift amount. The reflected wave power at this time is merely an example and is not limited thereto.

[0144] The shift amount and the initial shift direction of the frequency controlled by the second high frequency power source 90 at one time (the direction of the arrow of the third frequency) may be determined based on past data. The shift amount and the initial shift direction of the frequency controlled based on past data may be set in advance in a recipe and controlled based on the recipe. The past data may be the previous HF reflected wave power, the HF reflected wave power before the previous one, or the previous and previous HF reflected wave powers. For example, based on the state of the previous reflected wave power, the frequency shift direction and shift amount for each phase into which one LF cycle is divided may be determined so that the HF reflected wave power at each phase into which one LF cycle is divided is reduced. The shift direction and shift amount may be determined based on the state of the previous reflected wave power or the state of the previous reflected wave power before the previous one.

[0145] The frequency controlled by the second high frequency power supply 90 for the third time is shifted in the direction to reduce reflection, and the control timing at that time is such that, for example, if one LF cycle is divided into 10, the frequency is changed at a time interval obtained by dividing one LF cycle by 10.

[0146] From the fourth time onwards, the second high frequency power supply 90 oscillates the HF at an optimal frequency based on the data from the third time or data previously obtained before that. The frequency controlled by the second high frequency power supply 90 is repeated within the range of the allowable frequency a predetermined number of times or until the reflected wave power of the HF reaches a predetermined designated amount, thereby narrowing down the frequencies with small reflected wave power of the HF in each phase of one LF cycle.

[0147] In the control method according to the eighth modification of the embodiment, the above-described sequence is performed at a specified timing. This makes it possible to minimize the HF reflected wave power that varies depending on the LF phase and gas type. Examples of the specified timing include a synchro pulse period that is a time interval when one LF period is divided into n (n≧10), a time specified in a recipe, a predetermined time interval, etc.

[0148] [Variation 9] Next, a control method according to a ninth modification of an embodiment will be described with reference to Fig. 18. Fig. 18 is a timing chart for explaining a control method according to the ninth modification of an embodiment. In the control method according to the ninth modification of an embodiment, similarly to the eighth modification, the second high frequency power supply 90 controls the HF frequency in synchronization with each phase in one cycle of the LF, and also controls the value of the source power output by the second high frequency power supply 90.

[0149] For example, as shown in Fig. 18, in a time period around B1 where the reflected HF wave power is small, as shown at B, the second high frequency power supply 90 controls the HF frequency (see Fig. 17) and increases the output of the HF power (source power) as shown at D1. Conversely, in a time period B2 where the reflected HF wave power is large, the second high frequency power supply 90 changes the HF frequency and decreases the output of the source power as shown at D2.

[0150] In the control method according to the ninth modification of the embodiment, the reflected wave power of the HF, which varies depending on the phase of the LF and the type of gas, can be minimized, and the reduction in plasma density can be suppressed by increasing the source power when the reflected wave power of the HF is small. If the LF has a positive phase, the source power may be controlled in the range of the first source power to the second source power, and if the LF has a negative phase, the source power may be controlled in 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 may be different ranges or may be the same range, or one range may be included in the other range, or may partially overlap.

[0151] [Variation 10] Next, a control method according to the tenth modification of the embodiment will be described with reference to Fig. 19. Fig. 19 is a timing chart for explaining the control method according to the tenth modification of the embodiment.

[0152] The horizontal axis in FIG. 19 shows an example of one cycle of LF and one cycle of RF pulse. One cycle of RF pulse may be 0.1 to 100 kHz, may be longer or shorter than this, but is set to a time period longer than one cycle of LF. In the control method according to the tenth modification of the embodiment, the second high frequency power supply 90 may control the HF frequency according to each phase obtained by dividing one cycle of RF pulse into a plurality of phases. The HF frequency and the source power may be controlled according to each phase obtained by dividing one cycle of RF pulse into a plurality of phases.

[0153] In particular, immediately after the RF pulse is turned on and off, the plasma density Ne and the electrode potential change significantly, and the HF reflected wave power is likely to change differently from when the RF pulse is stationary. Therefore, as shown in Fig. 19, immediately after the time V when the RF pulse is turned on for each cycle, it takes time for the LF to rise, and the sheath thickness is thin (i.e., the sheath capacity is large). Therefore, immediately after the time V when the RF pulse is turned on, the second high frequency power supply 90 controls the HF frequency to be high (see E).

[0154] Also, in FIG. 19, the bias power is turned off during the latter half of the RF pulse (see C1). During this time, the HF reflected wave power is constant and close to 0, as shown by B3. That is, at the timing when the bias power is turned off and the source power is turned on, the bias power is turned off, so the sheath impedance is always constant. For this reason, the HF reflected wave power is constant. Therefore, while the bias power is turned off, the frequency is determined so that the HF reflected wave power is minimized, and the second high frequency power supply 90 outputs source power of the determined frequency.

[0155] While the bias power is off, the source power may be controlled to be off or on. For example, as shown in C1 of FIG. 19, while the bias power is off, in the first half, the HF frequency may be set to the frequency of E1, and the source power may be controlled to be High (or on), and in the second half, the HF frequency may be changed to the frequency of E2, and the source power may be controlled to be Low (or off). The periods for intermittently stopping the source power and the bias power may be the same, or the source power may be shifted behind the bias power, or the source power may be shifted ahead of the bias power. The stop time of the source power may be longer or shorter than the stop time of the bias power.

[0156] The control methods according to Modifications 8 to 10 are executed by the processor 100 in Fig. 2A, and a control signal for controlling the HF frequency and HF power is sent to the second high frequency power supply 90 via the signal generating circuit 102. The second high frequency power supply 90 changes the frequency and power of the HF to be output in accordance with the control signal.

[0157] [Variation 11] Next, a control method according to the eleventh modification of an embodiment will be described with reference to Fig. 20. Fig. 20 is a timing chart for explaining the control method according to the eleventh modification of an embodiment.

[0158] As described in the tenth modification, immediately after the RF pulse is turned on, it takes time for the LF to rise, and the sheath thickness is thin (i.e., the sheath capacity is large). Therefore, at the rise of the RF pulse, the plasma density Ne changes significantly, and the impedance fluctuates greatly.

[0159] Therefore, in the control method according to the eleventh modification, the second high frequency power supply 90 oscillates a composite wave of multiple frequencies at the rising timing of an RF pulse in one LF cycle, that is, at E3 in Fig. 20. The reflection detector 111 in Fig. 2A detects the reflected HF wave power for each of the multiple frequencies. The detected reflected HF wave power for each frequency is sent to the processor 100.

[0160] For example, assume that the second high frequency power supply 90 can amplify frequencies from 35 MHz to 45 MHz and oscillates composite waves of five frequencies, 41, 42, 43, 44, and 45 MHz. The reflection detector 111 detects the reflected wave power relative to the source power of each of the five frequencies and sends the results to the processor 100. The processor 100 selects the frequency with the smallest reflected wave power from among these frequencies.

[0161] For example, if the frequency with the least reflected wave power is 41 MHz, the frequency may be determined to be 41 MHz at the timing of the rise of the RF pulse in the next LF cycle, and may be set as the HF frequency output from the second high frequency power supply 90. Also, at E4 in Fig. 20, for example, source power may be output at five frequencies of 39, 40, 41, 42, and 43 MHz, with the center being the frequency of 41 MHz, which had the least reflected wave power in the previous cycle.

[0162] This allows the HF frequency output from the second high frequency power supply 90 to quickly reach the target frequency at which the reflected HF wave power is the lowest. As a result, the source power output from the second high frequency power supply 90 can be brought to a frequency at which the reflected HF wave power is the lowest more quickly, and plasma can be ignited more quickly.

[0163] When the processor 100 executes the control method according to the eleventh modification, a control signal for controlling the HF frequency is sent to the second high frequency power supply 90 via the signal generating circuit 102 based on the HF reflected wave power corresponding to the multiple frequencies detected by the reflection detector 111 in FIG. 2A.

[0164] However, without being limited thereto, the second high frequency power supply 90 may have the function of the above-mentioned processor 100. In this case, the HF reflected wave power corresponding to the multiple frequencies detected by the reflection detector 111 is sent directly from the reflection detector 111 to the second high frequency power supply 90.

[0165] In this case, the second high frequency power supply 90 can be realized as a variable frequency power supply having a control unit having the function of the processor 100. That is, in this case, the control unit of the variable frequency power supply acquires the HF reflected wave power corresponding to each of the multiple HF frequencies from the reflection detector 111, and selects the frequency with the least reflected wave power based on the acquired HF reflected wave power. Then, the control unit determines to output source power of the selected frequency from the variable frequency power supply. The variable frequency power supply changes the frequency of the source power to the determined frequency and outputs it with a predetermined power. This allows the second high frequency power supply 90 to control the frequency and source power of the output HF without using the processor 100 and the signal generating circuit 102. This allows the second high frequency power supply 90 to execute the control methods of Modifications 8 to 11 without using the processor 100.

[0166] Although the control method of Modification 11 uses a high frequency wave obtained by combining multiple frequencies, a high frequency wave obtained by combining multiple frequencies can also be used in the control methods of Modifications 8 to 10. In addition, the mixing ratio of the high frequency waves of multiple frequencies can be freely changed or optimized in the control methods of Modifications 8 to 10.

[0167] The control methods of variants 8 to 11 described above provide a control method for a plasma processing apparatus having a first electrode on which a workpiece is placed, the control method comprising the steps of supplying bias power to the first electrode and supplying a source power having a higher frequency than the bias power to a plasma processing space, the source power having a first state and a second state, and including a first control step of controlling the first state and the second state to two or more frequencies according to each phase obtained by dividing a phase within one period of a reference electrical state indicating any one of a voltage, a current or an electromagnetic field measured in a power supply system of the bias power into a plurality of phases.

[0168] [Variation 12] In the twelfth modification, the first state of the HF voltage has a pulsed voltage value that repeats two or more voltage values. In the example of Fig. 21, the first state of the HF voltage repeats a positive voltage value and a voltage value of 0. However, this is not limited to this, and two or more voltage values ​​may be repeated, such as repeating three voltage values.

[0169] [Variation 13] The bias power may be a sine wave or pulse wave, or may be a tailored waveform. That is, the bias voltage or current may be a sine wave, an LF pulse wave, or a tailored waveform as shown in FIG. 22. In the tailored waveform, the bias power may be modulated when the HF shown in FIG. 22 is in the second state, or the bias power may be modulated when the HF is in the first state.

[0170] Similarly, when the first state of HF has two or more voltage values, the waveform of HF may be a tailored waveform as shown in FIG. 22, in addition to the waveforms shown in FIGS. 15A to 15D and FIG. 21.

[0171] The plasma processing apparatus and control method according to the presently disclosed embodiment should be considered as illustrative and not restrictive in all respects. The above-described embodiment can be modified and improved in various forms without departing from the scope and spirit of the appended claims. The matters described in the above-described embodiments can be configured in other ways as long as they are not inconsistent. Furthermore, the matters described in the above-described embodiments can be combined as long as they are not inconsistent.

[0172] The plasma processing apparatus according to the present disclosure can be applied to any type of plasma processing apparatus, including Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP).

[0173] For example, a control method for a plasma processing apparatus having a first electrode on which a workpiece is placed and a second electrode opposite the first electrode may include a step of supplying a bias power to the first electrode and a step of supplying a source power having a frequency higher than the bias power to a plasma processing space, the source power having a first state and a second state, and a first control step of alternately applying the first state and the second state in synchronization with a phase within one period of the reference electrical state.

[0174] The present invention may include a control method for a plasma processing apparatus having a first electrode on which a workpiece is placed, the control method comprising the steps of: supplying a bias power to the first electrode; and supplying a source power having a frequency higher than the bias power to a plasma processing space, the source power having a first state and a second state, the control method including a first control step of alternately applying the first state and the second state in synchronization with a phase within one period of the reference electrical state.

[0175] The step of supplying a source power having a higher frequency than the bias power to the plasma processing space may be performed by a plasma generation source for generating plasma supplying source power such as a microwave source, a high frequency power source, or the like to the plasma processing space.

[0176] In this specification, the wafer W has been described as an example of the object to be processed, but the substrate is not limited to this and may be various substrates used in LCDs (Liquid Crystal Displays) and FPDs (Flat Panel Displays), CD substrates, printed circuit boards, etc. [Explanation of symbols]

[0177] 1...Plasma processing device 10...Treatment vessel 16...Placement table (lower electrode) 34…Top electrode 47...Power rod 46…matching box 48…First high frequency power source 50...Variable DC power supply 66…Processing gas supply source 84…Exhaust system 88…matching box 89…Power supply rod 90…Second high frequency power source 91...GND block 100…Processor 102...signal generating circuit 105,108...Directional coupler 111...Reflection detector 112…Oscilloscope 200...Control unit 250…Additional circuit 300…Impedance change circuit 350…Electromagnet

Claims

1. A chamber, a stage configured to support a substrate within the chamber; a first power supply configured to provide a bias to the stage; a second power source configured to supply high frequency power having an oscillation frequency that is the inverse of a period shorter than the period of the waveform of the bias; A control unit; Equipped with The control unit is (a) controlling the first power supply to supply the bias to the stage; (b) controlling the second power source to supply the high frequency power; (c) setting the oscillation frequency of the high frequency power in each phase of an n-th cycle (n is an integer) of the waveform of the bias based on a degree of reflection of the high frequency power in the same phase of a cycle of the waveform of the bias prior to the n-th cycle; (d) changing the value of n and executing (c); The plasma processing apparatus is configured to perform the steps of:

2. A plasma processing apparatus as described in claim 1, wherein in (c), the period of the waveform of the bias prior to the nth period is the (n-N)th period, where N is a constant and is an integer greater than or equal to 1.

3. A plasma processing apparatus as described in claim 1 or 2, wherein the control unit is configured to perform (a), (b), (c), and (d) during a process.

4. A first electrode provided on the stage; a second electrode facing the first electrode; Further comprising: the first power supply supplies the bias to the first electrode; The second power supply supplies the high frequency power to the first electrode or the second electrode. The plasma processing apparatus according to any one of claims 1 to 3.

5. The second power source supplies the high frequency power to the stage. The plasma processing apparatus according to any one of claims 1 to 4.

6. A plasma processing device comprising: an electromagnet disposed above or within a plasma processing space in the chamber; The control unit is configured to control the electromagnet to control a magnetic field in the plasma processing space. The plasma processing apparatus according to any one of claims 1 to 5.

7. The first power supply supplies the bias with the period of the waveform of the bias being the inverse of a frequency in the range of 0.1 kHz to 13.56 MHz. The plasma processing apparatus according to any one of claims 1 to 6.

8. The vibration frequency is 13.56 MHz or more. The plasma processing apparatus according to any one of claims 1 to 7.

9. The control unit is configured to control the second power source to change the vibration frequency in each of time intervals obtained by dividing the n-th period by 10 or more. The plasma processing apparatus according to any one of claims 1 to 8.

10. A plasma processing apparatus as described in any one of claims 1 to 9, wherein the waveform of the bias is a sine wave, a pulse wave, or a tailored waveform.

11. The degree of reflection is a reflected wave power of the high frequency power. The plasma processing apparatus according to any one of claims 1 to 10.

12. The control unit is configured to adjust the vibration frequency so that the degree of reflection is reduced. The plasma processing apparatus according to any one of claims 1 to 11.

13. The control unit is configured to repeatedly execute (d) until a predetermined designated number of times. The plasma processing apparatus according to any one of claims 1 to 12.

14. The control unit is configured to repeatedly execute (d) until the degree of reflection of the high frequency power reaches a predetermined designated amount. The plasma processing apparatus according to any one of claims 1 to 12.

15. A plasma processing apparatus comprising: a first power supply configured to provide a bias to a stage configured to support a substrate within a chamber of the plasma processing apparatus; a second power source configured to supply high frequency power having an oscillation frequency that is the inverse of a period shorter than the period of the waveform of the bias; Equipped with (a) providing the bias from the first power supply to the stage; (b) supplying the high frequency power from the second power source; (c) setting the oscillation frequency of the high frequency power in each phase of an n-th cycle (n is an integer) of the waveform of the bias based on a degree of reflection of the high frequency power in the same phase of a cycle of the waveform of the bias prior to the n-th cycle; (d) changing the value of n and executing (c); A power system configured to:

16. The method of claim 1, further comprising: (a) providing a bias from a first power supply to a stage configured to support a substrate within a chamber of a plasma processing apparatus; (b) supplying high frequency power from a second power source having an oscillation frequency that is the reciprocal of a period shorter than the period of the waveform of the bias; (c) setting the oscillation frequency of the high frequency power in each phase of an n-th cycle (n is an integer) of the waveform of the bias based on a degree of reflection of the high frequency power in the same phase of a cycle of the waveform of the bias prior to the n-th cycle; (d) changing the value of n and executing (c); A control method comprising:

17. A program for causing a plasma processing apparatus to execute the control method described in claim 16.

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