Plasma processing apparatus, power supply system, control method, and program

Abstract

To control the quantity and quality of radicals and ions.SOLUTION: A plasma processing apparatus includes a stage, a first high frequency power supply for supplying a bias waveform oscillating at a first frequency, the cycle of the bias waveform lasting for a predetermined period, and the bias waveform being applied to the stage, a second high frequency power supply for supplying 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 for changing the second frequency during the cycle of the bias waveform such that the reflected wave power is reduced, and controlling the second high frequency power supply 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 Art

[0002] There is known a technique of making ions reach a polycrystalline silicon layer by synchronizing high-frequency power for ion drawing applied during etching with the on / off of high-frequency power for plasma generation, and 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

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, etching rate is controlled by applying high-frequency power of two different frequencies, that is, source power which is high-frequency power for plasma generation and bias power which is high-frequency power for ion drawing, into a processing chamber.

[0005] The present disclosure provides a technique for controlling the quantity and quality of radicals and ions.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, there is provided a plasma processing apparatus including: a stage; a first high-frequency power supply configured to supply a bias waveform oscillating at a first frequency, a cycle of the bias waveform lasting for a predetermined period, and the bias waveform being applied to the stage; a second high-frequency power supply configured to supply 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 configured to control the second high-frequency power supply so as to control a power level of the source waveform during the cycle of the bias waveform.

Advantages of the Invention

[0007] According to one aspect, it is possible to control the quantity and quality of radicals and ions.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Embodiments for carrying out the present invention will be described with reference to the drawings. In the present specification and the drawings, substantially the same configurations are denoted by the same reference numerals, and redundant descriptions are 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". Further, the frequency (high frequency) of the bias power having a frequency 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] [First] When two high-frequency powers with different frequencies, namely the source power which is high-frequency power for plasma generation and the bias power which is high-frequency power for ion drawing, are applied into the processing container, IMD (Intermodulation distortion) may occur as reflected wave power.

[0012] IMD not only causes impedance mismatch, but also requires a high-frequency power supply with a capacity capable of inputting power greater than the originally required high-frequency power for the sake of reflection resistance and plasma maintenance. For this reason, conventionally, in order to reduce the generation of IMD, the cable length of the coaxial cable used in the power supply line of the high-frequency power supply has been optimized.

[0013] However, IMD occurs at the frequencies of the sum or difference between the fundamental wave and / or harmonics of HF power and the fundamental wave and / or harmonics of LF power. Therefore, in a method of optimizing the cable length of a coaxial cable, although the reflected wave power of high-frequency power at a specific frequency can be reduced, the reflected wave power at other frequencies resulting from the sum or difference between the fundamental wave and / or harmonics of HF power and LF power included in IMD cannot be eliminated.

[0014] Also, the lower the frequency of LF power, the more likely IMD is to occur at a frequency close to the fundamental wave of HF power. Therefore, it is conceivable to increase the frequency of LF power as much as possible to suppress the occurrence of IMD at frequencies close to the fundamental wave of HF power. However, in recent years, especially in high aspect ratio etching processes, better process results are obtained when the frequency of LF power is lowered. That is, the etching rate decreases as the depth of etching of high aspect ratio holes increases. Therefore, the frequency of LF power is set to a lower frequency and the power is increased. As a result, the etching rate can be increased in high aspect ratio etching. However, under these process conditions, IMD further increases. Therefore, due to the high power and low frequency of LF power in recent years, the reflected wave power of high-frequency power has become high. In particular, the reflected wave power of high-frequency power increases when LF power and HF power are applied to the same electrode.

[0015] For example, FIG. 12 shows an example of the reflected wave power generated when HF power of a predetermined frequency is applied to an electrode to which LF power is applied. The intensity of IMD changes periodically in synchronization with the phase of LF's Vpp (Peak to Peak). For example, in the example of FIG. 12, IMD is almost 0 W, that is, there is no reflection, when the LF potential is near the positive maximum value. Also, IMD is relatively low when the LF potential is in the negative range. After the LF potential exceeds the positive maximum value and becomes negative, the maximum reflected wave power is generated and IMD is at its maximum.

[0016] Therefore, the inventors propose a control method for suppressing the generation of IMD according to the phase of LF in consideration of the timing at which IMD occurs, and a plasma processing apparatus that executes the control method. Further, the inventors propose a control method for controlling the high-frequency power of two different frequencies of LF and HF to control the quantity and quality of radicals and ions.

[0017] [Overall Configuration of Plasma Processing Apparatus] 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 an embodiment is a capacitively coupled parallel plate plasma processing apparatus, and has, for example, a cylindrical processing container 10 made of aluminum whose surface is anodized. The processing container 10 is grounded.

[0019] At the bottom of the processing container 10, a cylindrical support base 14 is disposed 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 base 14. The mounting table 16 constitutes a lower electrode, and a wafer W, which is an example of a workpiece, is placed thereon via an electrostatic chuck 18.

[0020] An electrostatic chuck 18 for adsorbing and holding the wafer W by electrostatic force is provided on the upper surface of the mounting table 16. The electrostatic chuck 18 has a structure in which an electrode 20 made of a conductive film is sandwiched between a pair of insulating layers or insulating sheets. A DC power supply 22 is connected to the electrode 20. The DC voltage output from the DC power supply 22 is applied to the electrode 20. The wafer W is adsorbed and held by the electrostatic chuck 18 by the electrostatic force such as the Coulomb force generated thereby.

[0021] A conductive edge ring 24 made of, for example, silicon is disposed on the mounting table 16 and around the wafer W. The edge ring 24 is also referred to as 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 base 14.

[0022] Inside the support table 14, for example, a refrigerant chamber 28 is provided in an annular shape. In the refrigerant chamber 28, a refrigerant at a predetermined temperature, for example, cooling water, is circulated and supplied from a chiller unit provided outside through pipes 30a and 30b, and the processing temperature of the wafer W on the mounting table 16 is controlled by the temperature of the refrigerant. Note that the refrigerant is an example of a temperature-adjusting medium circulated and supplied through the pipes 30a and 30b, and the temperature-adjusting medium may not only cool the mounting table 16 and the wafer W but also heat them.

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

[0024] Above the mounting table 16, an upper electrode 34 is provided in parallel so as to face the mounting table 16. The space between the upper electrode 34 and the lower electrode becomes a plasma processing space. The upper electrode 34 forms a surface that faces the wafer W on the mounting table 16 and is in contact with the plasma processing space, that is, a facing surface.

[0025] The upper electrode 34 is supported by the upper part of the processing container 10 through an insulating shielding member 42. The upper electrode 34 includes an electrode plate 36 that constitutes a facing surface with the mounting table 16 and has a large 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 is anodized. The electrode plate 36 may be formed of, for example, silicon or SiC. Inside the electrode support 38, a gas diffusion chamber 40 is provided, and a large number of gas flow holes 41 communicating 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 guiding the processing gas to 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. The gas supply pipe 64 is provided with a mass flow controller (MFC) 68 and an on-off valve 70 in order from the upstream side. Then, the processing gas for etching is supplied from the processing gas supply source 66. The processing gas reaches the gas diffusion chamber 40 from the gas supply pipe 64 and is discharged shower-like into the plasma processing space from the gas discharge holes 37 through 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 switch for turning on and off the current and voltage are controlled by the control unit 200.

[0028] A first high-frequency power supply 48 is connected to the mounting table 16 via a power supply rod 47 and a matcher 46. The first high-frequency power supply 48 applies LF power to the mounting table 16. Thereby, ions are drawn into the wafer W on the mounting table 16. The first high-frequency power supply 48 outputs LF power having a frequency in the range of 200 kHz to 13.56 MHz. The matcher 46 matches the internal impedance of the first high-frequency power supply 48 and the load impedance.

[0029] A second high-frequency power supply 90 is connected to the mounting table 16 via a power supply rod 89 and a matcher 88. The second high-frequency power supply 90 applies HF power to the mounting table 16. The frequency of the HF is higher than that of the LF, and HF power with a frequency of 13.56 MHz or higher is output from the second high-frequency power supply 90. For example, HF power with a frequency of 100 MHz, which is higher in frequency, may be output with respect to LF power of 400 kHz. The matcher 88 matches the internal impedance of the second high-frequency power supply 90 and the load impedance. A filter 94 for passing a predetermined high frequency to the ground may be connected to the mounting table 16. Note that 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 container 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 container 10 can be depressurized to a desired degree of vacuum. In addition, a carry-in / carry-out port 85 for the wafer W is provided on the side wall of the processing container 10, and the carry-in / carry-out port 85 can be opened and closed by a gate valve 86. Further, a deposition shield 11 for preventing etching by-products (deposits) from adhering to the processing container 10 is detachably provided along the inner wall of the processing container 10. That is, the deposition shield 11 constitutes the wall of the processing container. In addition, the deposition shield 11 is also provided on the outer periphery of the inner wall member 26. An exhaust plate 83 is provided between the deposition shield 11 on the wall side of the bottom of the processing container 10 and the deposition shield 11 on the inner wall member 26 side. As the deposition shield 11 and the exhaust plate 83, those obtained by coating an aluminum material with ceramics such as Y2O3 can be used.

[0031] When performing an etching process with the plasma processing apparatus 1 having such a configuration, first, the gate valve 86 is opened, and the wafer W to be etched is carried into the processing container 10 through the carry-in / outlet 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 supplied into the processing container 10 through the gas flow holes 41 and the gas discharge holes 37. Further, the inside of the processing container 10 is 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, as the processing gas, various conventionally used ones can be adopted, and for example, a gas containing a halogen element such as C4F8 gas can be preferably used. Further, other gases such as Ar gas and O2 gas may be included.

[0032] In a state where the etching gas is introduced into the processing container 10 in this way, HF power is applied from the second high-frequency power source 90 to the mounting table 16. Also, LF power is applied from the first high-frequency power source 48 to the mounting table 16. Further, a DC voltage is applied from the variable DC power source 50 to the upper electrode 34. Also, a DC voltage is applied from the DC power source 22 to the electrode 20 to adsorb and hold the wafer W on the mounting table 16.

[0033] The processing gas discharged from the gas discharge holes 37 of the upper electrode 34 is mainly dissociated and ionized by the HF power to generate plasma. The surface of the wafer W to be processed is etched by radicals and ions in the plasma. Also, by applying LF power to the mounting table 16, the ions in the plasma can be controlled, and the control margin of the plasma can be widened, such as enabling the etching of high aspect ratio holes.

[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 is set with process time, pressure (gas exhaust), high-frequency power and voltage, various gas flow rates, temperature inside the processing chamber (upper electrode temperature, side wall temperature of the processing chamber, wafer W temperature, electrostatic chuck temperature, etc.), temperature of the refrigerant output from the chiller, etc., which are control information of the apparatus for process conditions. Note that the recipe indicating these programs and processing conditions may be stored in a hard disk or a semiconductor memory. Further, the recipe may be set at a predetermined position in a state of being accommodated in a portable computer-readable storage medium such as a CD-ROM or a 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 any of the voltage, current, or electromagnetic field measured in the power supply system of the bias power. 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. Thereby, the amount and quality of ions and radicals can be controlled. Also, the generation of IMD can be reduced.

[0036] The power supply system of the bias power refers to the first high-frequency power source 48 → matcher 46 → power supply rod 47 → stage 16 → (plasma) → upper electrode 34 → (ground). Any of the voltage, current, or electromagnetic field measured in the power supply system of the bias power refers to the voltage, current, or electromagnetic field measured by the parts from the first high-frequency power source 48 to the inside of the matcher 46 and through the power supply rod 47 to the stage 16 and the upper electrode 34.

[0037] Also, the state of a signal synchronized with the high-frequency period of the bias power supply, or any one of the voltage, current, or electromagnetic field measured in the power supply system of the bias power supply, is also referred to as the "reference electrical state". The HF power (source power) is controlled to be alternately applied to the first state and the second state described below in synchronization with the phase within one period of the reference electrical state.

[0038] However, when any one of the voltage, current, or electromagnetic field measured in the power supply system of the bias power supply is defined as the "reference electrical state", the reference electrical state is preferably any one of the voltage, current, or electromagnetic field measured in any member up to the inside of the matcher connected from the mounting table 16 via the power supply rod 47.

[0039] As a method for measuring the reference electrical state in the power supply system of the bias power supply, an example is a method of measuring the voltage, current, or induced magnetic field of each part by installing a voltage probe, current probe, or BZ probe (probe for measuring the induced magnetic field) near any part of the power supply system of the bias power supply.

[0040] For example, FIG. 2B(a) is an example when any one of the voltage, current, or electromagnetic field measured in the power supply system of the bias power supply is defined as the "reference electrical state". For example, in FIG. 2B(a), the processor 100 inputs any one of the HF voltage or current, LF voltage or current, HF phase signal, or LF phase signal from a sensor such as a VI probe attached to the power supply system. The processor 100 alternately applies the source power to 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, LF voltage or current, HF phase signal, or LF phase signal.

[0041] Processor 100 may generate a signal synchronized with the high-frequency period of the bias power output from the first high-frequency power source 48 without relying on the signal from the sensor. In this case, the state of this signal can be used as the reference electrical state. Also, the step of measuring the reference electrical state in the power supply system of the bias power 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 the information of the bias power from the first high-frequency power source 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 source 90. The second high-frequency power source 90 alternately applies the source power between the first state and the second state based on this signal.

[0042] Note that the processor 100 may generate a signal synchronized with the high-frequency period of the bias power without relying on the signal from the first high-frequency power source 48. In this case, the processor 100 generates a signal having a period shown as LF in FIG. 3, for example, and generates an on-off signal shown as HF in FIG. 3, for example, synchronized with this signal. The processor 100 outputs the generated signal to the first high-frequency power source 48 and the second high-frequency power source 90. The first high-frequency power source 48 outputs the bias power based on this signal. The second high-frequency power source 90 alternately applies the source power between the first state and the second state based on this signal.

[0043] Note that the mounting table 16 is an example of the first electrode for mounting the wafer W. The upper electrode is an example of the second electrode facing the first electrode. The first high-frequency power source 48 is an example of a bias power source that supplies LF power to the first electrode. The second high-frequency power source 90 is an example of a source power source that supplies HF power with a frequency higher than that of 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 source and the source power source. 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] [Configuration of the control unit] The specific configuration of the control unit 200 will be described with reference to FIG. 2A. The control unit 200 includes a processor 100, a signal generation circuit 102, directional couplers 105 and 108, a reflection detector 111, and an oscilloscope 112.

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

[0046] The directional coupler 105 supplies a part of the LF traveling wave power (Pf) to the oscilloscope 112. The directional coupler 108 supplies a part of the HF traveling wave power and the reflected wave power to the oscilloscope 112.

[0047] In one embodiment, the frequency of the LF displayed on the oscilloscope 112 is, for example, 400 kHz, and the frequency of the HF is, for example, 100 MHz. Thus, on the oscilloscope 112, the waveform of the LF traveling wave power, the waveform of the HF traveling wave power, and the waveform of the HF reflected wave power can be observed.

[0048] Also, the directional coupler 108 separates a certain ratio of the HF reflected wave and supplies it to the reflection detector 111. The reflection detector 111 is composed of, for example, a spectrum analyzer, a power meter, etc., and measures the IMD (Intermodulation distortion) of any wavelength and its magnitude, and the magnitude of the reflected wave power. The IMD refers to the reflected wave power from the plasma side generated by applying HF power to the upper electrode or the lower electrode of the plasma processing apparatus 1 (in one embodiment, the lower electrode) and applying LF power to the lower electrode, which occurs according to the sum or difference frequency of the fundamental wave and / or harmonic wave of LF and the fundamental wave and / or harmonic wave of HF.

[0049] The directional coupler 105 supplies a part 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 synchronized with the positive timing of the LF traveling wave. Instead of the directional coupler 105, the waveform of LF detected using a sensor such as a VI probe may be supplied to the processor 100.

[0050] The processor 100 supplies the created synchronization signal to the signal generation circuit 102. The signal generation circuit 102 generates a control signal synchronized with the LF traveling-wave power from the supplied synchronization signal and supplies it 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 a part of the voltage or current of LF output from the first high-frequency power supply 48 as a waveform and inputs it to the processor 100. However, it is not limited to this, and the processor 100 may directly input a part of the power of LF or the like 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 generation circuit 102. The on-signal is an example of a synchronization signal.

[0052] The signal generation 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, a control signal for generating HF power during the on-signal or the on-signal itself is used for the command signal.

[0053] When the first high-frequency power supply 48 is an amplifier that amplifies the power, voltage, or current of LF, the signal from the directional coupler 105 is not used, and the signal generation circuit 102 may extract a part of the power of LF 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 waveform signal. The signal generation circuit 102 transmits the waveform signal and the on-signal to the second high-frequency power supply 90.

[0054] However, the above method for generating the control signal is only an example and is not limited thereto. As long as a control signal can be generated that controls the on / off of the HF power or alternately applies High / Low in synchronization with the phase within one cycle of the reference electrical state (such as the phase within one cycle of the LF voltage or current, the electrode potential, etc.) from the given synchronization signal, it is not limited to the circuit of the control unit 200 shown in FIG. 2A, and other hardware or software can be used.

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

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

[0057] The processor 100 may create a synchronization signal that controls the HF power during a time period including the positive timing of the electrode potential. However, the processor 100 is not limited thereto, and may also create a synchronization signal that controls the HF power during a short time period including the timing when the electrode potential is most negative.

[0058] [Timing of HF Power Supply] Next, the timing of HF power supply in an embodiment will be described with reference to FIG. 4. FIG. 4 is a diagram showing an example of the timing of HF power supply according to an embodiment.

[0059] The vertical axes in FIGS. 4(a) to 4(c) indicate the potential of the electrode. The potential of the electrode is almost the same as that of the wafer. The potential of the electrode is the potential when the LF and HF voltages are superimposed. Here, the Vpp of the LF voltage with an LF frequency of 400 kHz is much larger than the Vpp of the HF voltage with an HF frequency of 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] Regarding the sheath on the electrode, basically, the thickness of the sheath is determined according to the LF voltage. The electrode potential when the LF voltage is negative becomes deeper negative than the electrode potential when the LF voltage is positive due to the so-called self-bias voltage Vdc. When the electrode potential is at a positive potential with respect to the ground potential, it approaches the plasma potential, so some high-speed electrons can flow into the electrode. When it is at a negative potential with respect to the ground potential, ions flow in.

[0061] Since the electrode is floating from the ground by a blocking capacitor (a matcher in one embodiment), the electrons flowing into the electrode do not flow to the ground. Therefore, electrons flow into and accumulate on the electrode during the 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 and a negative bias is generated with respect to the plasma. Due to that negative bias, ions start to flow into the surface of the electrode. Thereby, a sheath is formed on the surface of the electrode.

[0062] Finally, the surface of the electrode approaches the plasma potential, and the DC component of the electrode potential when the electrons flowing in at that time and the ions constantly flowing in due to the negative bias are in equilibrium is the self-bias voltage Vdc.

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

[0064] When the electrode potential becomes deeply negative when the voltage of LF is negative due to the self-bias voltage Vdc, since the thickness of the sheath is proportional to the voltage, a large voltage is applied to the electrode when the electrode potential is negative, and the thickness of the sheath becomes thick. On the other hand, when the electrode potential is positive, a smaller voltage is applied to the electrode compared to when the electrode potential is negative, so the thickness of the sheath becomes thin.

[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. Corresponding to the phase of LF, there are a timing when the thickness of the sheath on the mounting table 16 is in a substantially flat and thin state and a timing when the sheath is thick. Therefore, assuming the sheath as a capacitor, when the sheath is thin, the capacitance of the capacitor becomes large, and from the impedance Z = 1 / ωC, the impedance Z of the sheath becomes low. That is, when the electrode potential is positive, since the sheath is thin, the impedance Z is low and almost constant. On the other hand, when the electrode potential is negative, since the sheath is thick, the impedance Z is high and the change becomes large. Furthermore, the impedance Z is almost determined by the voltage of LF. From the above, impedance matching of HF power becomes difficult. In particular, when the electrode potential is negative, that is, when the voltage of LF is negative, since the impedance is high and the change is large, impedance matching of HF power becomes difficult.

[0066] In response to such variations in impedance Z, the matcher 88 that performs impedance matching for HF power can follow up to a frequency of about 1 Hz at most due to the operation of the motor. However, at frequencies higher than that, it becomes difficult to follow up and achieve matching, and it will match at one timing among the impedances that change moment by moment according to the LF phase. In this state, since the matcher 88 cannot achieve matching at phases other than the one timing at which matching has been achieved, the reflected wave power of the IMD is large.

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

[0068] In one embodiment, when the electrode potential is positive, since the impedance Z is substantially constant, it is easy to achieve matching by supplying HF power at this timing. Therefore, at this timing, the HF power is controlled to be on or High. On the other hand, when the electrode potential is negative, since the impedance is high and the change is large, it is difficult to achieve matching even if HF power is supplied at this timing. Therefore, at this timing, the supply of HF power is controlled to be off or Low. This can reduce the generation of IMD.

[0069] As shown in FIG. 4(b), when controlling the HF power to be High or Low, since the HF power is held at Low instead of being turned off at the timing when the electrode potential is negative, a decrease in plasma density can be suppressed compared to the case of controlling the HF power to be on or off. Also, by making the HF power applied at the timing when the electrode potential is negative smaller than the HF power applied at the timing when the electrode potential is positive, the generation of IMD can be suppressed.

[0070] However, the control method of turning on or setting the HF power to High in accordance with the timing when the electrode potential is positive is just an example and is not limited thereto. The HF power may be controlled to be turned on or set to High when at least a part of the phase of the reference electrical state is positive. Further, the HF power may be controlled to be turned on or set to 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 the timing at which the phase of the reference electrical state peaks. The peak in this case may be a positive peak or a negative peak. Further, the period of the first state may include the timing at which at least a part of the phase of the reference electrical state is positive. Further, the period of the first state may include the timing at which at least a part of the phase of the reference electrical state is negative. Further, the HF power may be applied not only as a rectangular wave synchronized 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 slow ramp-up at the rising edge or a slow ramp-down at the falling edge. Further, the HF power may be applied at least one of the timings shifted by a predetermined time after or before the timing when the phase of the reference electrical state is positive.

[0071] Examples 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 include the following cases. When the HF power is applied only when the phase of the reference electrical state is positive, the ion energy becomes small. Depending on the type of etching, a process with a larger ion energy may be desired. In that case, the HF power is applied until the timing at which the reference electrical state of LF changes from positive to negative and the desired ion energy is obtained. Thereby, a process with a large ion energy can be realized.

[0072] Further, based on the timing when the phase of the reference electrical state is positive, the time width for supplying the HF power may be adjusted so that the HF power is made shorter or longer for a predetermined time. For example, the HF power may be supplied by adding a predetermined time before and after the timing when the phase of the reference electrical state is positive.

[0073] HF power may be supplied at a timing when the phase of the reference electrical state is negative. However, at a timing 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 to turn on the HF power within a shorter time width at a timing when the phase of the reference electrical state is negative. For example, it is preferable to adjust the timing and width of applying the HF power in a circuit having a gate function or a delay function. In advance, measure the reflection intensity in one cycle of the reference electrical state, and control using a circuit having an automatic adjustment function to apply the HF power at a timing when the reflection of the LF power is small based on the measurement result.

[0074] For example, as shown in FIG. 4(c), at a timing when the electrode potential is negative, turn on or set the HF power to High within a short time width including the time when the self-bias Vdc of the electrode becomes most negative, and turn off or set the HF power to Low in other time zones. Also, detect the reflected wave power in advance and, according to its magnitude, turn off or set the HF power to Low in a time zone with a large reflected wave power, and turn on or set the HF power to High in a time zone with a small reflected wave power. By applying the HF power for a short time within the time width including the time when the electrode potential shown in FIG. 4(c) becomes most negative, strong ion implantation can be realized in a specific etching such as HARC (High Aspect Ratio Contact). Thereby, improvement in etching speed and improvement in etching shape can be realized.

[0075] As described above, according to the control method of the plasma processing apparatus 1 according to one embodiment, the on / off or High / Low of the HF power is controlled in synchronization with the phase within one cycle of the reference electrical state. Thereby, the generation of IMD can be reduced. Also, it becomes possible to control the ion energy and control the quantity and quality of radicals and ions.

[0076] Note that, as shown in an example in FIGS. 3 and 4(a) to 4(c), the state in which the power of HF is controlled to be on or High is an example of the first state, and the state in which the power of HF is controlled to be off or Low is an example of the second state.

[0077] In the control method of the plasma processing apparatus 1 according to an embodiment, there is a first control step of alternately applying the first state and the second state in synchronization with the phase within one cycle of the reference electrical state. The second state may be smaller than the first state, and the power of the second state may be 0, or may be a value smaller than the first state other than 0.

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

[0079] The graph of FIG. 5 is the measured result obtained by periodically applying and measuring the power of HF with a time width of about 40% of one cycle of the reference electrical state while changing the phase. The left vertical axis of the graph indicates the plasma density Ne (cm -3 ), and the right vertical axis indicates the absolute value |Vdc| (V) of the self-bias. When the power of HF and the power of LF are superimposed and applied to the lower electrode of the plasma processing apparatus 1, the sheath of the lower electrode fluctuates with the cycle of LF, and as a result, the impedance Z changes, and the plasma density Ne and the self-bias Vdc fluctuate.

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

[0081] Also, when the power of HF is turned off at the timing when the electrode potential is positive and the power of HF is turned on for a short time including the time when the electrode potential becomes most negative (see the upper right figure in FIG. 5), as shown in region b of the lower graph in FIG. 5, the plasma density Ne becomes medium to high, and the plasma generation efficiency becomes medium or higher. This is because when the electrode potential is negative, a large voltage is applied to the electrode, the sheath thickness becomes thick, the electric field of HF when the power of HF is turned on decreases, and the plasma generation efficiency decreases.

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

[0083] As described above, according to the plasma processing apparatus 1 according to one embodiment, for example, by controlling the power of HF to be turned on or set to High based on the timing when the electrode potential is positive, the generation of IMD can be reduced. Also, as an issue that the plasma generation efficiency decreases due to the thickening of the sheath at the timing when the electrode potential is negative, the plasma generation efficiency can be increased by applying the power of HF at the timing when the electrode potential is positive.

[0084] Also, by applying the power of HF only for a short time at the timing when the electrode potential is negative and deepest, monochromatized high-energy ions can be drawn into the wafer W.

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

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

[0087] According to this, in region d, the reflected wave power is smaller than that in region c. Therefore, by synchronizing a signal with the high-frequency period of the bias power so that the phase of LF includes 0°, or synchronizing with the phase within one period of the reference electrical state measured in the power supply system of the bias power, and alternately applying the HF power to the first state (e.g., on or High state) and the second state (e.g., off or Low state), it can be understood that the generation of IMD can be suppressed. For example, as described above, by setting the HF power to the first state at the timing when the electrode potential is positive and setting the HF power to the second state at 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. Also, by controlling the HF power to the first state and the second state at an arbitrary timing according to the electrode potential, high-energy ions can be drawn into the wafer W using the region where the plasma density Ne is high and the region where the absolute value |Vdc| of the self-bias is large. Also, in this case, by applying the HF power in a pulsed manner, the generation of IMD can be reduced as a whole.

[0088] Figure 7 shows an example of LF Vpp, LF |Vdc|, the traveling wave power (Pf) of HF, and the reflected wave power (Pr) of HF. According to this, the reflected wave power (Pr) of HF varies up to about 5 times (about 10 W to about 50 W) at most in the phase of one period of the LF voltage. From the above, there is a possibility that the IMD can be reduced to about 1 / 5 by controlling the HF power in synchronization with the phase within one period of the reference electrical state. Also, it can be understood that for LF Vpp and LF |Vdc| as well, they can be varied in a range up to about 1.6 times the minimum value by controlling the HF power in synchronization with the phase within one period of the reference electrical state.

[0089] [Modification Example] Next, the 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 the control method according to Modification 1 of an embodiment. FIG. 9 is a diagram for explaining the control method according to Modification 2 of an embodiment. FIG. 10 is a diagram for explaining the control method according to Modification 3 of an embodiment. FIG. 11 is a diagram for explaining the control method according to Modification 4 of an embodiment.

[0090] (Modification 1) In the embodiment described above, when attempting to pulse-modulate the HF power in synchronization with the phase within one cycle 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] Therefore, in the plasma processing apparatus 1 according to Modification 1, as shown in FIG. 8(a), an additional circuit 250 that constitutes 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 and grounded to the processing container 10.

[0092] By increasing the ratio of the impedance on the processing container 10 side to the load impedance on the plasma side by the additional circuit 250, even if the impedance changes compared to the case where the additional circuit 250 is not present, the additional circuit 250 can mitigate the large change in the combined impedance Z of the additional circuit 250 and the impedance on the processing container 10 side. For example, as shown in FIG. 8(b), by reducing the change in the combined impedance Z by the additional circuit 250, the generation of IMD can be more effectively suppressed when HF power is applied in synchronization with the phase within one cycle of the reference electrical state. Also, simply by installing the additional circuit 250, a mechanism for suppressing IMD can be constructed simply and inexpensively. Note that it is preferable to insert the additional circuit 250 on the second high-frequency power supply 90 side after the branching of the power supply rod because the HF power is less likely to be affected by the LF power. If a filter is provided between the first high-frequency power supply 48 and the second high-frequency power supply 90, the HF power is even less likely to be affected by the LF power, the variation in the combined impedance Z can be reduced, and the generation of IMD can be more effectively suppressed. The additional circuit 250 may include at least one of an element such as a coil, a capacitor, or a diode.

[0093] (Modification 2) In the plasma processing apparatus 1 according to Modification 2, as shown in FIG. 9(a), an impedance change circuit 300 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. The impedance change circuit 300 functions to change the impedance so that the combined 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 LF phase so as to suppress the change in the impedance seen from the matching unit 88. Thereby, the reflected wave power can be suppressed and the generation of IMD can be reduced. The impedance change circuit 300 changes the impedance within one cycle of the reference electrical state according to the LF phase (or impedance), LF Vdc, reflected wave power, etc., thereby suppressing IMD.

[0094] As an example of the impedance change circuit 300, a configuration in which capacitors are provided in an array and the connection of the capacitors is switched by an electronic switch can be mentioned. The control unit 200 controls the electronic switch to change the impedance of the impedance change circuit 300.

[0095] For example, as shown in FIG. 9(b), the control unit 200 switches the connection of the capacitors 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. Thereby, when HF power is applied in synchronization with the phase within one cycle of the reference electrical state, impedance matching becomes good and the generation of IMD can be further suppressed.

[0096] The impedance change circuit 300 may be inserted inside the matcher 88 and integrated with the matcher 88. It is preferable that the impedance change circuit 300 is inserted on the second high-frequency power supply 90 side after the branching of the power supply rod because the HF power is less likely to be affected by the LF power. If a filter is provided between the first high-frequency power supply 48 and the second high-frequency power supply 90, the HF power is even less likely to be affected by the LF power, the variation of the combined impedance Z can be reduced, and the generation of IMD can be further suppressed.

[0097] (Modification 3) In Modification 3, as shown in Fig. 10(a), an electromagnet 350 is provided above the processing container 10. The position of the electromagnet 350 is not limited to the position shown in Fig. 10(a), and it may be a part of the processing container 10, for example, it may be inside the processing container 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 electrical state, the phase of the LF, the electrode potential to which the bias power is applied, the reflected wave power of the LF Vdc or HF, etc. 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 the impedance Z. Thereby, the generation of IMD can be further suppressed. Note that the electromagnet 350 can use a multipole electromagnet or a fixed magnet, and is an example of a magnetic field generation unit that generates a magnetic field. The control by the electromagnet 350 shown in Modification 3 may be used in combination with the control by the additional circuit 250 of Modification 1 or the impedance change circuit 300 of Modification 2.

[0098] (Modification 4) When the thickness of the sheath changes, the apparent capacitance changes, and the resonance frequency of the HF changes. The matching unit 88 functions to sum all the L components and C components of the inductance (for example, the feeding rod, etc.) and the conductance (for example, the sheath, etc.) in the processing container 10 so as to resonate at the HF frequency and achieve matching.

[0099] Therefore, when the thickness of the sheath changes, the C component changes, so originally, the matching unit 88 should re-match according to the change in the C component due to the change in the thickness of the sheath, otherwise the reflected wave power will increase. However, since it takes about 1 second for the matching unit 88 to move the variable capacitor, it cannot follow the change in the thickness of the sheath and may not be able to achieve accurate matching.

[0100] Therefore, in Modification 4, the control unit 200 changes the HF frequency by the amount of change in the C component due to the change in the sheath thickness. That is, based on the supply frequency formula of f (supply frequency) ∝ 1 / √LC, the HF frequency f is changed according to the change in the C component corresponding to the thickness of the sheath.

[0101] For example, assuming that the capacitance of the sheath on the electrode is C, if the capacitance C changes by a factor of 4 in response to a change in the thickness of the sheath, the HF frequency is changed by approximately a factor of 2. Thereby, it is possible to achieve a state of generally being in agreement with the change in the thickness of the sheath.

[0102] Also, if the capacitance C changes by a factor of 10 in response to a change in the thickness of the sheath, the HF frequency is changed by approximately a factor of 3.3. Thereby, it is possible to achieve a state of generally being in agreement with the change in the thickness of the sheath. That is, in Modification 4, as shown in FIG. 11(a), the HF frequency is changed based on the above resonance frequency formula so as to match the change in the thickness of the sheath corresponding to the change in one cycle of the LF voltage. Thereby, a state of generally being in agreement with the change in the thickness of the sheath is achieved, the reflected wave power of the HF can be reduced, and the generation of IMD can be suppressed. In Modification 4, the second high-frequency power supply 90 uses a frequency-variable power supply capable of changing the HF frequency. Note that the control shown in Modification 4 may be used in combination with at least any one of the additional circuit 250 of Modification 1, the impedance change circuit 300 of Modification 2, or the electromagnet 350 of Modification 3.

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

[0104] Alternatively, 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), pulsed power (hereinafter also referred to as "LF pulse") corresponding to the peak of the LF voltage may be applied, and the timing of applying the HF power may be controlled according to the LF pulse. That is, for example, an LF pulse corresponding to an LF of 400 kHz may be turned on and off and applied, and accordingly, the HF power may be controlled in a pulsed manner (HF pulse). The power of the LF pulse corresponding to the peak of the phase of the reference electrical state may be applied, and the timing of applying the HF power may be controlled according to the LF pulse.

[0105] As described above, the intensity of generation of the IMD varies according to 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 modification examples, by selecting the timing with a low HF reflected wave power and applying the HF power at that timing, the generation of the IMD can be reduced. By reducing the generation of the IMD, the stability of the process and the plasma processing apparatus 1 can be improved, and further, the device cost can be reduced. Furthermore, it is possible to control the plasma density, the self-bias Vdc, etc.

[0106] However, when the time for applying the HF power decreases, there is a concern that the absolute amount of the HF power decreases and the plasma density Ne decreases. Therefore, the LF power and the HF power may be applied at each of the two timings including the time when the reference electrical state peaks twice within one cycle. In addition, the control method of applying the HF power can be freely changed. Note that the application of the 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 type 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 frequency higher than that of the bias power to the plasma processing space by applying the source power to the lower electrode or the upper electrode. In this control method, the source power has a first state and a second state, and includes a first control step of alternately applying the first state and the second state in synchronization with a signal synchronized with the high-frequency cycle of the bias power, or with the phase within one cycle of a reference electrical state indicating any one of voltage, current, or electromagnetic field measured in the power supply system of the bias power.

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

[0109] [Modification Examples 5-1 to 5-4] Next, the control method of the plasma processing apparatus 1 according to modification examples 5-1 to 5-4 of one embodiment will be described. In modification examples 5-1 to 5-4, control is performed to intermittently stop the source power and / or the bias power. FIGS. 13A to 13D are timing charts showing the control method according to modification examples 5-1 to 5-4 of one embodiment.

[0110] In modification example 5-1 of FIG. 13A, in addition to the first control step, it includes a second control step of intermittently stopping the source power in a cycle independent of the cycle of the reference electrical state shown by an example with an LF voltage. The first control step and the second control step are repeatedly executed.

[0111] In Modification Example 5-1, the LF voltage is applied in the same cycle in the first control step and the second control step. On the other hand, the source power alternately repeats the first state and the second state one or more times in the first control step and is intermittently stopped during the first control step in the second control step.

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

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

[0114] The control method according to Modification Example 5-2 of FIG. 13B includes, in addition to the same first control step as in Modification Example 5-1, a third control step of intermittently stopping the bias power in 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 Modification Example 5-2, the first control step and the third control step are repeatedly executed. In Modification Example 5-2, the source power in the third control step repeats the first state and the second state in the same cycle as the first control step.

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

[0117] The control method according to Modification Example 5-3 of FIG. 13C, in addition to the same first control step as in Modification Example 5-1, controls the source power in the second control step of Modification Example 5-1 and the bias power in the third control step of Modification Example 5-2. That is, the state in which both the source power and the bias power in Modification Example 5-3 are intermittently stopped is an example of the fourth state.

[0118] The cycle of intermittently stopping the bias power and the cycle of intermittently stopping the source power may be synchronized. In this case, the cycles of intermittently stopping the source power and the bias power may coincide as shown in FIG. 13C, or as shown in FIG. 13D, 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.

[0119] [Effects of the control methods according to Modification Examples 5-1 to 5-4] As described above, in the control methods according to Modification Examples 5-1 to 5-4, the quality and quantity of radicals and ions can be controlled. Specifically, when HF is turned off, the ions in the plasma almost disappear, but since the radicals have a long lifetime, they exist without disappearing for a certain period of time. Therefore, for example, the radicals can be uniformly diffused while HF is turned off. Also, the ratio of ions to radicals in the plasma can be changed while HF is turned off or controlled to Low. Thereby, the quantity of radicals and ions can be controlled.

[0120] Also, as the dissociation of the gas proceeds, radicals corresponding to the progress of the dissociation are generated. For example, C4F8 gas dissociates as C4F8 → C4F7 * → ···· → CF2, and different radicals (C4F7 * etc.) are generated according to the degree of dissociation. Parameters for promoting the dissociation include ion energy and reaction time. Therefore, by controlling the application timing and application time of the bias power and the source power, the ion energy and / or the reaction time can be controlled, and the quality of radicals and ions can be controlled by promoting the generation of radicals suitable for the process.

[0121] Also, while the bias power is off, the etching does not progress because the ion energy decreases, and the by-products deposited at the bottom of the hole or the like can be removed outside the hole and deposited on the mask. Further, while the bias power is off, radicals can be attached to the pattern surface on the wafer W. Thereby, the radicals attached on the mask protect the mask, and the mask selectivity can be improved. Thereby, the etching can be promoted, the etching rate can be increased, and the etching shape can be improved.

[0122] In the above, an example of the effect when the source power is intermittently stopped has been described, but it is not limited thereto. For example, plasma may be generated by the bias power, and the same effect may be obtained when the bias power is intermittently stopped. That is, by intermittently stopping the bias power, the quality and quantity of radicals and ions can be controlled. Thereby, the etching rate can be increased and the etching shape can be improved.

[0123] Note that in FIGS. 13A to 13D, in the third state, the source power is on at the timing when the LF Vdc is deeply negative, but it is not limited thereto, and the source power may be on at the timing when the LF Vdc is positive or other timings. Further, instead of periodically turning on and off the source power, it may be periodically controlled to High and Low.

[0124] [Modification Example 6] Next, a control method according to Modification Example 6 of an embodiment will be described with reference to FIG. 14. FIG. 14 is a timing chart showing the control method according to Modification Example 6 of an embodiment.

[0125] For example, in the control method according to Modification Example 6, as shown in FIG. 14, an LF pulse is applied to the mounting table 16. 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 Modification 6, the first state and the second state of the HF are alternately applied in synchronization with the phase within one cycle of the LF pulse. Also by this, the amount and quality of radicals and ions can be controlled.

[0127] Specifically, the source power may be controlled to be off or low during part or all of the period when the LF pulse is positive, and the source power may be controlled to be on or high during part or all of the period when the LF pulse is negative. According to this, the LF pulse is binary, and accordingly, the source power is binarized and controlled, so that the control becomes easy. Although FIG. 14 shows the control of the HF state shown in FIG. 13A corresponding to the LF pulse obtained by pulsing the LF voltage in FIG. 13A, the present invention is not limited to this. For example, the HF states shown in FIGS. 13B to 13D may be controlled corresponding to the LF pulses obtained by pulsing the LF voltages in FIGS. 13B to 13D.

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

[0129] In the control methods according to Modifications 7-1 and 7-2 shown in FIGS. 15A and 15B, in the first control step, the first state and the second state of the source power are alternately applied in synchronization with the phase within one cycle of a reference electrical state using the LF voltage or the electrode potential as an example. In Modification 7-1, the first state of the source power has two or more states stepwise in synchronization with the negative timing of the electrode potential. Also, in Modification 7-2, the first state of the source power has two or more states smoothly 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] In the control methods according to Modification Examples 7-3 and 7-4 shown in FIGS. 15C and 15D, in addition to the first control step, there is a second control step. In the first control step, the first state and the second state of the source power are alternately applied in synchronization with the phase within one cycle of the reference electrical state using the LF voltage as an example. In Modification Example 7-3, in synchronization with the positive timing of the electrode potential, the first state of the source power has two or more states stepwise. Also, in Modification Example 7-4, in synchronization with the positive timing of the electrode potential, the first state of the source power has two or more states smoothly. However, the first state of the source power may be synchronized with the negative timing of the electrode potential.

[0131] In Modification Examples 7-1 to 7-4, by controlling the source power in the first state to a plurality of values, the amounts and qualities of radicals and ions can be controlled more accurately. In addition to the first control step shown in FIGS. 15C and 15D, instead of the second control step of FIGS. 15C and 15D, it may have the third control step shown in FIG. 13B, or may have the second and third control steps shown in FIGS. 13C and 13D.

[0132] In the control method according to Modification Example 3 of an 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, etc. Thereby, by reducing the change in impedance seen from the matching units 46, 88, the generation of IMD can be suppressed. Also, in the control method according to Modification Example 4 of an embodiment, the frequency of the HF is changed by the amount of change in the C component due to the change in the sheath thickness. That is, based on the formula of the supply frequency of f (supply frequency) ∝ 1 / √LC, the frequency f of the HF is changed according to the change in the C component corresponding to the thickness of the sheath. Thereby, it becomes a state where generally matching is achieved according to the change in the thickness of the sheath, the reflected wave power of the HF can be reduced, and the generation of IMD can be suppressed. In Modification Example 4, the second high-frequency power supply 90 uses a frequency-variable power supply 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 it so that the reflected power of the source power is minimized. However, when controlling the source power in synchronization with the phase within one cycle of the LF voltage or current, the HF load varies periodically and significantly within one cycle of the LF voltage or current. Therefore, the second high-frequency power supply 90 needs to change the frequency corresponding to the sheath thickness that varies periodically and significantly according to the LF phase within one cycle, more preferably, the impedance corresponding to the sheath thickness.

[0134] For example, FIG. 16 is a diagram showing an example of the HF reflected power (HF-Pr) according to an embodiment. The HF reflected power varies depending on the gas type and the LF phase. For example, FIG. 16(a) shows an example of the HF reflected power (see B) when argon gas is supplied into the processing chamber 10, a traveling-wave power (HF-Pf) of 500 W of HF is applied (see A), and an LF power of 1000 W is applied. FIG. 16(b) shows an example of the HF reflected power (see B) when SF6 gas is supplied into the processing chamber 10, a traveling-wave power of 500 W of HF 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 stage 16. The potential of the wafer is approximately equal to the Vpp of the LF voltage when the LF frequency is, for example, 400 kHz, and the width (amplitude) of the Vpp of the HF voltage when the HF frequency is, for example, 100 MHz is added, and it oscillates with both potentials.

[0135] Looking at B in FIGS. 16(a) and (b), it can be seen that the way the HF reflected power appears with respect to the phase within one cycle of the LF is different between the case where argon gas is supplied and the case where SF6 gas is supplied.

[0136] Changing the output frequency of HF output from the second high-frequency power supply 90 in real time according to the difference in the direction of the reflected wave power of HF is not practical because it takes time for the second high-frequency power supply 90 to determine the optimal frequency. For example, a normal frequency variable power supply can measure the reflected wave power by shifting the frequency at a maximum of 1 kHz to 10 kHz. On the other hand, for example, for an LF of 400 kHz, when one cycle is divided into 10 parts, it becomes 4 MHz. Furthermore, in order to shift the wavelength 10 times within the division, the wavelength needs to be changed at 40 MHz, and it is necessary to determine the change direction of the reflected amount and frequency of HF in real time in synchronization with this. This operation cannot be achieved with the operating frequency of a normal frequency variable power supply and is not practical.

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

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

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

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

[0141] In the second cycle of 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 cycle of C). However, in the second time, the frequency is not increased or decreased for each phase corresponding to the number of divisions in one period of the LF. Instead, the frequency is set to either increase or decrease, and the phase-dependent result of the reflection amount is obtained. In the example of the second time in FIG. 17, an example in which the frequency (the second frequency) is increased is shown, but it may be decreased.

[0142] As a result, it can be seen that the power of the second reflected wave of HF indicated by the solid line B in FIG. 17 has areas where the reflection decreases and areas where it increases depending on the phase, compared to the power of the first reflected wave of HF indicated by the dashed line B. In FIG. 17, there is a time period when the reflected wave power of HF decreases when LF has a positive phase, and the reflected wave power of HF increases when LF has a negative phase. However, the reflected wave power at this time is only an example and is not limited to this.

[0143] In the third cycle of FIG. 17, within the third one-cycle period of LF, the shift direction and shift amount of the frequency controlled by the second high-frequency power source 90 are determined based on the increase and decrease of the reflected wave power of HF for each previous phase. The third frequency shown in FIG. 17 is an example of the determined shift direction and shift amount. Also, the reflected wave power at this time is only an example and is not limited to this.

[0144] The shift amount of the frequency and the initial shift direction (the direction of the arrow of the third frequency) that the second high-frequency power source 90 controls at one time may be determined based on past data. The shift amount of the frequency and the initial shift direction controlled based on past data may be set in a recipe in advance and controlled based on the recipe. The past data may be the previous reflected wave power of HF, or the reflected wave power of HF from the time before the previous time, or the reflected wave power of HF from the previous time and before that. For example, based on the state of the previous reflected wave power, the shift direction and shift amount of the frequency for each phase obtained by dividing one cycle of LF may be determined so that the reflected wave power of HF in each phase decreases for each phase obtained by dividing one cycle of the next LF. In addition to the state of the previous reflected wave power, or instead of the state of the previous reflected wave power, the shift direction and shift amount may be determined based on the state of the past reflected wave power before the previous time.

[0145] The frequency controlled by the second high-frequency power source 90 in the third time is shifted in the direction where the reflection decreases. At that time of control timing, for example, when one cycle of LF is divided into 10, the frequency is changed at time intervals obtained by dividing one cycle of LF into 10.

[0146] After the fourth time, the second high-frequency power supply 90 oscillates HF at an optimal frequency based on the data from the third time or the data obtained in advance before that. The frequency controlled by the second high-frequency power supply 90 is within the allowable frequency range and is repeated until a predetermined number of times or until the reflected wave power of HF reaches a predetermined specified amount, so that the frequency at which the reflected wave power of HF is small at each phase of one cycle of LF can be narrowed down.

[0147] In the control method according to Modification Example 8 of an embodiment, the sequence described above is performed at a specified timing. Thereby, the reflected wave power of HF that changes according to the phase of LF and the gas species can be minimized as much as possible. As an example of the specified timing, a sync pulse period of a time interval when one cycle of LF is divided into n (n≥10) parts, a time specified in a recipe, a predetermined time interval, etc. can be mentioned.

[0148] [Modification Example 9] Next, with reference to FIG. 18, a control method according to Modification Example 9 of an embodiment will be described. FIG. 18 is a timing chart for explaining the control method according to Modification Example 9 of an embodiment. In the control method according to Modification Example 9 of an embodiment, similar to Modification Example 8, in addition to the second high-frequency power supply 90 controlling the frequency of HF in synchronization with each phase within one cycle of LF, the value of the source power output by the second high-frequency power supply 90 is also controlled.

[0149] For example, as shown in FIG. 18, in the time zone near B1 where the reflected wave power of HF indicated by B is small, the second high-frequency power supply 90 controls the frequency of HF (see FIG. 17) and increases the output of the HF power (source power) indicated by D to D1. Conversely, in the time zone of B2 where the reflected wave power of HF is large, the second high-frequency power supply 90 changes the frequency of HF and decreases the output of the source power to D2 as shown.

[0150] In the control method according to Modification Example 9 of an embodiment, the reflected wave power of HF that changes according to the phase of LF or the gas type can be minimized as much as possible, and when the reflected wave power of HF is small, the source power can be increased to suppress the decrease in plasma density. If LF has a positive phase, the source power may be controlled within the range of the first source power to the second source power, and if LF has a negative phase, the source power may be controlled within the range of the third source power to the fourth source power. The range of the first source power to the second source power and the range of the third source power to the fourth source power may be different ranges, the same range, one range may be included in the other range, or they may overlap partially.

[0151] [Modification Example 10] Next, with reference to FIG. 19, a control method according to Modification Example 10 of an embodiment will be described. FIG. 19 is a timing chart for explaining the control method according to Modification Example 10 of an embodiment.

[0152] On the horizontal axis of FIG. 19, an example of one cycle of LF and one cycle of RF pulses is shown. One cycle of the RF pulse may be 0.1 to 100 kHz, longer than this, or shorter than this, but is set to a time period longer than one cycle of LF. In the control method according to Modification Example 10 of an embodiment, the second high-frequency power supply 90 may control the frequency of HF according to each phase obtained by dividing the phase of one cycle of the RF pulse into a plurality of phases, for example. The frequency and source power of HF may be controlled according to each phase obtained by dividing the phase of one cycle of the RF pulse into a plurality of phases.

[0153] In particular, immediately after the RF pulse is turned on and off, the change in plasma density Ne and the change in electrode potential are large, and the reflected wave power of HF is likely to change differently from that during the steady state of the RF pulse. Therefore, as shown in FIG. 19, immediately after the time V when the RF pulse of each cycle is turned on, it takes time for LF to rise, and the sheath thickness is thin (that is, the capacitance of the sheath is large). For this reason, immediately after the time V when the RF pulse is turned on, the second high-frequency power supply 90 controls the frequency of HF to be high (see E).

[0154] Also, in FIG. 19, the bias power is off during the latter half of the RF pulse (see C1). During this period, the HF reflected wave power is nearly constant and close to 0 as shown at B3. That is, at the timing when the bias power is off and the source power is on, since the bias power is off, the impedance of the sheath is always constant. For this reason, the HF reflected wave power becomes constant. Therefore, while the bias power is off, the frequency is determined so that the HF reflected wave power is minimized, and the second high-frequency power supply 90 outputs the 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 at C1 in FIG. 19, while the bias power is off, the HF frequency is set to the frequency of E1 in the first half, and the source power is controlled to be High (or on), and in the second half, the HF frequency is changed to the frequency of E2, and the source power may be controlled to be Low (or off). Note that the periods for intermittently stopping the source power and the bias power may coincide, 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] Note that 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 the HF power via the signal generation circuit 102 is sent to the second high-frequency power supply 90. The second high-frequency power supply 90 changes the output HF frequency and power according to the control signal.

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

[0158] As described in Modification Example 10, 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 capacitance of the sheath is large). Therefore, at the rise of the RF pulse, the plasma density Ne changes greatly, and the impedance fluctuates greatly.

[0159] Therefore, in the control method according to Modification Example 11, the second high-frequency power supply 90 oscillates a composite wave of a plurality of frequencies at the rising timing of the RF pulse in one cycle of the LF, that is, at the time of E3 in FIG. 20. The reflection detector 111 in FIG. 2A detects the HF reflection wave power for each of the plurality of frequencies. The detected HF reflection wave power for each frequency is sent to the processor 100.

[0160] For example, when the second high-frequency power supply 90 can amplify the frequency from 35 MHz to 45 MHz, and it is assumed that a composite wave of five frequencies of 41, 42, 43, 44, and 45 MHz is oscillated. Among these, the reflection detector 111 detects the reflection wave power for the source power of the five frequencies respectively and sends it to the processor 100. The processor 100 selects the frequency with the least reflection wave power from among these.

[0161] For example, when the frequency with the least reflection wave power is 41 MHz, at the rising timing of the RF pulse in the next one cycle of the LF, the frequency may be determined to be 41 MHz and used as the HF frequency output from the second high-frequency power supply 90. Also, at E4 in FIG. 20, for example, the source power of five frequencies of 39, 40, 41, 42, and 43 MHz may be output centered on the frequency of 41 MHz, which had the least reflection wave power last time.

[0162] Thereby, the frequency of the HF output from the second high-frequency power supply 90 can reach the target frequency with the least HF reflection wave power at the fastest speed. As a result, the source power output from the second high-frequency power supply 90 can be brought to a frequency with less HF reflection wave power earlier, and the plasma can be ignited earlier.

[0163] In addition, when the processor 100 executes the control method according to the first modification example 11, a control signal for controlling the frequency of HF is sent to the second high-frequency power supply 90 via the signal generation circuit 102 based on the HF reflected wave power corresponding to a plurality of frequencies detected by the reflection detector 111 in FIG. 2A.

[0164] However, it is not limited to this, and 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 a plurality of frequencies detected by the reflection detector 111 is directly sent 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 with 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 a plurality of HF frequencies from the reflection detector 111, and selects the frequency with the lowest reflected wave power based on the acquired HF reflected wave power. Then, the control unit determines to output the 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. Thereby, the second high-frequency power supply 90 can control the output HF frequency and source power without using the processor 100 and the signal generation circuit 102. Thereby, the second high-frequency power supply 90 can execute the control methods of the eighth to eleventh modification examples without using the processor 100.

[0166] In the control method of the eleventh modification example, a high frequency obtained by synthesizing a plurality of frequencies is used. However, in the control methods of the eighth to tenth modification examples, a high frequency obtained by synthesizing a plurality of frequencies can also be used. Further, the mixing ratio of the high frequencies of the plurality of frequencies may be freely changed or may have a sequence for optimizing in the control methods of the eighth to tenth modification examples.

[0167] In the control methods of Modification Examples 8 to 11 described above, there is provided a control method for a plasma processing apparatus having a first electrode on which an object to be processed is placed, the method including a step of supplying a bias power to the first electrode and a step of supplying a source power having a frequency higher than that of 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 source power to two or more frequencies according to each phase when a cycle of a reference electrical state indicating any one of a signal synchronized with a high-frequency cycle of the bias power, or a voltage, a current, or an electromagnetic field measured in a power supply system of the bias power is divided into a plurality of phases.

[0168] [Modification Example 12] In Modification Example 12, the first state of the HF voltage takes 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, the present invention is not limited to this, and two or more voltage values may be repeated, such as repeating three voltage values.

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

[0170] Similarly, when the first state of HF takes two or more voltage values, the waveform of HF may be a tapered waveform 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 one embodiment disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiment can be modified and improved in various forms without departing from the scope and gist of the appended claims. Matters described in the above plurality of embodiments can also adopt other configurations within a non - conflicting range. Also, matters described in the above plurality of embodiments can be combined within a non - conflicting range.

[0172] The plasma processing apparatus according to the present disclosure is applicable to any type of 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 facing the first electrode, the method including 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, wherein the source power has a first state and a second state, and may include a first control step of alternately applying the first state and the second state in synchronization with the phases within one cycle of the reference electrical state.

[0174] A control method for a plasma processing apparatus having a first electrode on which a workpiece is placed, the method including 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, wherein the source power has a first state and a second state, and includes a first control step of alternately applying the first state and the second state in synchronization with the phases within one cycle of the reference electrical state.

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

[0176] In this specification, the wafer W has been described as an example of the object to be processed. However, the substrate is not limited to this, and may be various substrates used for LCD (Liquid Crystal Display), FPD (Flat Panel Display), CD substrates, printed circuit boards, etc.

Explanation of Signs

[0177] 1…Plasma processing apparatus 10…Processing container 16…Mounting table (lower electrode) 34…Upper electrode 47…Power feeding rod 46…Matcher 48…First high-frequency power source 50…Variable DC power source 66…Processing gas supply source 84…Exhaust device 88…Matcher 89…Power feeding rod 90…Second high-frequency power source 91…GND block 100…Processor 102…Signal generation 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. 2. The plasma processing apparatus of claim 1, wherein in (c), a period of the waveform of the bias prior to the nth period is the (n-N)th period, where N is a constant and an integer equal to or greater than 1.

3. The plasma processing apparatus according to claim 1 , wherein the control unit is configured to execute the steps (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. 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 source supplies the bias with the period of the waveform of the bias being an 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 so as 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. 10. The plasma processing apparatus according to claim 1, wherein the waveform of the bias is a sine wave, a pulse wave, or a tailored waveform.

11. The degree of reflection is the 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 first power supply configured to provide a bias to a stage configured to support a substrate within a chamber of the plasma processing device; 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. (a) providing a bias from a first power supply to a stage configured to support a substrate within a chamber of a plasma processing device; (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. 17. A program for causing a plasma processing apparatus to execute the control method according to claim 16.

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