Plasma processing apparatus and processing method

Abstract

To provide a technology that removes unnecessary components from a signal which reflects a matching state of impedance of a load of a high frequency power source, in a plasma processing apparatus.SOLUTION: In a plasma processing apparatus disclosed, a high frequency power source supplies high-frequency power for generating plasma. A bias power supply supplies electric bias energy having a bias frequency for drawing of ions to an electrode of a substrate support part. The high frequency power source adjusts a frequency of high-frequency power in each of a plurality of phase periods within a period of electric bias energy. A sensor detects an electric signal that reflects a deviation from a matching state of impedance of a load of the high frequency power source. A filter removes mutual modulation distortion components between the high-frequency power and the electric bias energy from the electric signal detected by the sensor in each of the plurality of phase periods.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Exemplary embodiments of the present disclosure relate to plasma processing apparatus and methods. [Background technology]

[0002] A plasma processing apparatus is used in plasma processing of a substrate. In the plasma processing apparatus, a high frequency bias power is used to attract ions from a plasma generated in a chamber to the substrate. The following Patent Document 1 discloses a plasma processing apparatus that modulates the power level and frequency of the high frequency bias power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-246091 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for removing unnecessary components from a signal reflecting the impedance matching state of a load of a high frequency power supply in a plasma processing apparatus that uses a high frequency power supply to generate high frequency power having a variable frequency for generating plasma. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a bias power supply, a matcher, a radio frequency power supply, a sensor, and a filter. The substrate support is disposed within the chamber. The bias power supply is configured to supply electrical bias energy to an electrode of the substrate support to attract ions from a plasma generated within the chamber to a substrate placed on the substrate support. The electrical bias energy has a bias frequency. A period of the electrical bias energy has a time length that is the inverse of the bias frequency. The matcher has a matching circuit. The radio frequency power supply is configured to supply radio frequency power having a variable frequency through the matcher to generate a plasma from a gas within the chamber. The radio frequency power supply is configured to adjust a frequency of the radio frequency power in each of a plurality of phase periods within a period of the electrical bias energy. The sensor is configured to detect an electrical signal reflecting a deviation of an impedance of a load of the radio frequency power supply from a matched state. The filter is configured to generate a filtered signal by removing intermodulation distortion components of the radio frequency power and the electrical bias energy from the electrical signal detected by the sensor in each of the plurality of phase periods. Effect of the Invention

[0006] According to one exemplary embodiment, in a plasma processing apparatus using a high frequency power supply that generates high frequency power having a variable frequency in generating plasma, it is possible to remove unnecessary components from a signal that reflects the impedance matching state of the load of the high frequency power supply. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment; [Diagram 2] 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment; [Diagram 3] FIG. 1 is a diagram showing an example of the configuration of a high-frequency power supply in a plasma processing apparatus according to an exemplary embodiment. [Figure 4] 4 is a timing chart of an example of frequencies of electrical bias energy and high frequency power. [Diagram 5] FIG. 2 is a diagram illustrating an example of a frequency spectrum of an electrical signal. [Figure 6] 1 is a flow diagram of a processing method according to one exemplary embodiment. [Figure 7] FIG. 13 is a diagram showing another example filter configuration that may be employed in a plasma processing apparatus according to an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a bias power supply, a matcher, a radio frequency power supply, a sensor, and a filter. The substrate support is disposed within the chamber. The bias power supply is configured to supply electrical bias energy to an electrode of the substrate support to attract ions from a plasma generated within the chamber to a substrate placed on the substrate support. The electrical bias energy has a bias frequency. A period of the electrical bias energy has a time length that is the inverse of the bias frequency. The matcher has a matching circuit. The radio frequency power supply is configured to supply radio frequency power having a variable frequency through the matcher to generate a plasma from a gas within the chamber. The radio frequency power supply is configured to adjust a frequency of the radio frequency power in each of a plurality of phase periods within a period of the electrical bias energy. The sensor is configured to detect an electrical signal reflecting a deviation of an impedance of a load of the radio frequency power supply from a matched state. The filter is configured to generate a filtered signal by removing intermodulation distortion components of the radio frequency power and the electrical bias energy from the electrical signal detected by the sensor in each of the plurality of phase periods.

[0010] In the above embodiment, the frequency of the high frequency power is adjusted in a plurality of phase periods within the period of the electrical bias energy. In each of the plurality of phase periods, intermodulation distortion components are removed from the electrical signal reflecting the deviation of the impedance of the load of the high frequency power source from the matching state according to the frequency of the high frequency power. Therefore, in a plasma processing apparatus using a high frequency power source that generates high frequency power having a variable frequency in generating plasma, it is possible to remove unnecessary components from the electrical signal reflecting the matching state of the impedance of the load of the high frequency power source.

[0011] In one exemplary embodiment, the high frequency power source may be configured to adjust the frequency of the high frequency power during each of a plurality of phase periods based on the filtered signal to bring the impedance of a load of the high frequency power source closer to a matching state.

[0012] In one exemplary embodiment, the electrical signal detected by the sensor may include a signal representative of the power of a reflected wave from a high frequency power load.

[0013] In one exemplary embodiment, the electrical signals detected by the sensor may include signals representative of the voltages and currents measured on the transmission line of the RF power.

[0014] In one exemplary embodiment, the high frequency power source may include an oscillator and an amplifier. The oscillator is configured to generate a high frequency signal. The amplifier is configured to amplify the high frequency signal to generate high frequency power. The plasma processing apparatus may further include a mixer. The mixer is configured to mix the high frequency signal and the electrical signal together to generate a mixed signal. The filter is configured to generate a filtered signal from the mixed signal, and has a pass band whose center frequency is zero. The width of the pass band of the filter is less than the bias frequency.

[0015] In one exemplary embodiment, the filter may include a plurality of filters having different passbands, and a filter among the plurality of filters, the passband of which includes the frequency of the high frequency power in each of the plurality of phase periods, may be applied to the electrical signal.

[0016] In one exemplary embodiment, the electrical bias energy may be a bias radio frequency power having a bias frequency, or the electrical bias energy may include pulses of voltage periodically generated at time intervals having a time length that is the inverse of the bias frequency, or a periodically generated voltage of any waveform.

[0017] In one exemplary embodiment, the plasma processing apparatus may further include an upper electrode provided above the substrate support. The high frequency power source may be electrically connected to the electrode of the substrate support or the upper electrode via a matching box.

[0018] In one exemplary embodiment, the plasma processing apparatus may further include a voltage sensor configured to detect a voltage of the electrical bias energy on a transmission line of the electrical bias energy, and the RF power source may be configured to identify a period and a plurality of phase periods of the electrical bias energy based on the voltage detected by the voltage sensor.

[0019] In another exemplary embodiment, a signal processing method is provided. The signal processing method includes the step of (a) supplying high frequency power from a high frequency power source through a matcher to generate plasma from a gas in a chamber of a plasma processing apparatus. The plasma processing apparatus includes a substrate support disposed in the chamber. The signal processing method further includes the step of (b) supplying electrical bias energy to an electrode of the substrate support to attract ions from the plasma to a substrate placed on the substrate support. The signal processing method further includes the step of (c) detecting, with a sensor, an electrical signal reflecting a deviation of an impedance of a load of the high frequency power source from a matched state. The signal processing method further includes the step of (d) generating a filtered signal from the electrical signal using a filter. The electrical bias energy has a bias frequency, and a period of the electrical bias energy has a time length that is the reciprocal of the bias frequency. The frequency of the high frequency power is variable. In the step (a), the frequency of the high frequency power in each of a plurality of phase periods in a period of the electrical bias energy is adjusted. In step (d), a filtered signal is generated by removing intermodulation distortion components of the high frequency power and the electrical bias energy from the electrical signal in each of the multiple phase periods.

[0020] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0021] 1 and 2 are diagrams that illustrate a plasma processing apparatus according to an exemplary embodiment.

[0022] In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas exhaust port is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is disposed in the plasma processing space, and has a substrate support surface for supporting a substrate.

[0023] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR plasma), a helicon wave plasma (HWP), a surface wave plasma (SWP), or the like.

[0024] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on a program stored in the storage unit 2a2. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0025] A configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1 will be described below. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a shower head 13. The substrate support 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The sidewall 10a is grounded. The shower head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0026] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W, and an annular region (ring support surface) 111b for supporting the ring assembly 112. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. In one embodiment, the main body 111 includes a base 111e and an electrostatic chuck 111c. The base 111e includes a conductive member. The conductive member of the base 111e functions as a lower electrode. The electrostatic chuck 111c is disposed on the base 111e. The upper surface of the electrostatic chuck 111c has a substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Although not shown, the substrate support 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 111c, the ring assembly 112, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0027] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

[0028] The gas supply 20 may include one or more gas sources 21 and at least one or more flow controllers 22. In one embodiment, the gas supply 20 is configured to supply one or more process gases from respective gas sources 21 through respective flow controllers 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include one or more flow modulation devices to modulate or pulse the flow rate of one or more process gases.

[0029] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0030] The plasma processing apparatus 1 further includes a high-frequency power supply 31 and a bias power supply 32. Hereinafter, reference will be made to Fig. 3 and Fig. 4 in addition to Fig. 2. Fig. 3 is a diagram showing an example of the configuration of a high-frequency power supply in a plasma processing apparatus according to an exemplary embodiment. Fig. 4 is a timing chart showing an example of the frequencies of electrical bias energy and high-frequency power.

[0031] The high frequency power supply 31 is configured to supply high frequency power RF (i.e., source high frequency power) to the high frequency electrode via a matching device 31m in order to generate plasma from the gas in the chamber 10. The frequency of the high frequency power RF, i.e., the source frequency f RF The high frequency power RF has a source frequency f of, for example, 13 MHz or more and 150 MHz or less. RF has.

[0032] The high frequency power supply 31 is electrically connected to the high frequency electrode via the matching device 31m. In one embodiment, the high frequency electrode may be an electrode of the substrate support 11. The high frequency electrode may be the base 111e. The matching device 31m includes a matching circuit. The matching circuit of the matching device 31m has a variable impedance. The matching circuit of the matching device 31m is controlled by the control unit 2 or a control unit 36 ​​described later. The impedance of the matching circuit of the matching device 31m is adjusted so as to match the impedance of the load side of the high frequency power supply 31 to the output impedance of the high frequency power supply 31. The high frequency electrode may be an electrode provided in the substrate support 11, separate from the base 111e. Alternatively, the high frequency electrode may be an upper electrode.

[0033] The bias power supply 32 is configured to supply an electric bias energy BE to a bias electrode of the substrate support 11 to attract ions from the plasma generated in the chamber 10 to a substrate W placed on the substrate support 11. The bias electrode may be the base 111e. The bias electrode may be an electrode provided in the substrate support 11 separate from the base 111e. The electric bias energy BE is generated at a bias frequency f B The period CY of the electrical bias energy (i.e., the bias period) is a function of the bias frequency f B The bias frequency f B is, for example, a frequency greater than or equal to 100 kHz and less than or equal to 13.56 MHz.

[0034] In one embodiment, the electrical bias energy BE is determined by a bias frequency f B The bias high frequency power LF may be a high frequency power having a waveform of a sinusoidal waveform in a period CY, that is, a bias high frequency power LF. When the electrical bias energy BE is the bias high frequency power LF, the bias power supply 32 is connected to the bias electrode via a matching device 32m. The matching device 32m includes a matching circuit. The matching circuit of the matching device 32m has a variable impedance. The matching circuit of the matching device 32m is controlled by the control unit 2 or the control unit 36. The impedance of the matching circuit of the matching device 32m is adjusted so as to match the impedance of the load side of the bias power supply 32 to the output impedance of the bias power supply 32.

[0035] In another embodiment, the electrical bias energy BE is determined by a bias frequency f B The voltage pulse PV used as the electric bias energy BE may be a voltage pulse PV periodically generated at a time interval (i.e., a period CY) having a time length that is the reciprocal of , or a voltage of any waveform. The voltage pulse PV used as the electric bias energy BE may be a negative voltage pulse or a negative DC voltage pulse. The voltage pulse PV may have any waveform, such as a triangular wave or a rectangular wave. When the voltage pulse PV is used as the electric bias energy BE, a filter that blocks high frequency power RF may be connected between the bias power supply 32 and the bias electrode, instead of the matching device 32m.

[0036] In one embodiment, the high frequency power supply 31 may include an oscillator 31g, an amplifier 31a, a filter 33, a mixer 34, a filter 35, and a control unit 36. Note that the filter 33, the mixer 34, the filter 35, and the control unit 36 ​​may be elements separate from the high frequency power supply 31.

[0037] The oscillator 31g is configured to generate a high-frequency signal. The high-frequency signal has a source frequency f RFThe amplifier 31a amplifies the high-frequency signal generated by the oscillator 31g to generate high-frequency power RF. The gain of the amplifier 31a is controlled by the control unit .

[0038] The control unit 36 ​​is configured with a processor. The control unit 36 ​​is connected to the control unit 2 so as to be able to communicate with each other. The source frequency f RF The gain of the amplifier 31a may initially be specified by the control unit 2 to the control unit 36 ​​in accordance with recipe data stored in the memory unit 2a2. The control unit 36 ​​may transmit a synchronization signal to the bias power supply 32 for synchronization between the high frequency power supply 31 and the bias power supply 32.

[0039] In the plasma processing apparatus 1, as shown in FIG. 4, the period CY of the electric bias energy BE is divided into a plurality of phase periods SP, that is, N phase periods SP1 to SP2. N Phase periods SP1 to SP N The time length of each phase period SP1 to SP N The respective time lengths may be the same as each other or may be different from each other.

[0040] In the plasma processing apparatus 1, during a period in which high frequency power RF is supplied and electrical bias energy BE is supplied, the source frequency f RF That is, during the nth phase period SP n Source frequency f at RFn is adjusted, where “n” is an integer from 1 to N. The source frequency f RF , i.e. the source frequency f RFn are designated by the control unit 36. In the example shown in FIG. N Each source frequency f RF3 , f RF5、 f RFN f0, f B , f A The oscillator 31g generates a source frequency f designated by the control unit 36 ​​during each of the multiple phase periods SP.RF A high frequency signal having a frequency of

[0041] In the high frequency power supply 31, the period CY and the multiple phase periods SP may be determined by the control unit 36. In one embodiment, the control unit 36 ​​may determine the period CY from the power of the traveling wave of the electrical bias energy BE acquired in the directional coupler 32d, and determine the multiple phase periods SP by dividing the period CY. The directional coupler 32d may be connected between the bias power supply 32 and the matching unit 32m.

[0042] Alternatively, the control unit 36 ​​may determine the period CY based on the voltage detected by the voltage sensor 32v, and determine the multiple phase periods SP by dividing the period CY. The voltage sensor 32v is configured to detect the voltage of the electric bias energy BE on the transmission path of the electric bias energy BE. The voltage sensor 32v may detect the voltage of the electric bias energy BE on the transmission path between the matching device 32m and the bias electrode.

[0043] In the plasma processing apparatus 1, one or more electrical signals are acquired by a sensor on a transmission path of the high frequency power RF during each of the multiple phase periods SP. Then, impedance matching is performed based on the acquired one or more electrical signals during each of the multiple phase periods SP. The one or more electrical signals reflect a deviation of the impedance of the load of the high frequency power supply 31 from a matched state.

[0044] The one or more electrical signals may include a signal representing a power Pr of a reflected wave from the load of high frequency power. The one or more electrical signals may further include a signal representing a power Pf of a forward wave from the load of high frequency power. The signal representing the power Pr of the reflected wave and the signal representing the power Pf of the forward wave are acquired by the directional coupler 31d. The directional coupler 31d is connected between the high frequency power supply 31 and the matching device 31m. The directional coupler 31d may be a part of the amplifier 31a. Alternatively, the directional coupler 31d may be a part of the matching device 31m.

[0045] One or more electrical signals are measured along the RF transmission path, and the RF voltage V RF The signal and current I RF The signal may include a signal representing the voltage V RF The signal and current I RF A signal representative of is measured by a sensor 31e, which may be part of a matching device 31m.

[0046] Each of the one or more electrical signals includes a harmonic component. The frequency of the harmonic component is f RF ±k×f RF where k is a natural number and is 1, 2, 3, . . . Each of the one or more electrical signals includes an intermodulation distortion component between the radio frequency power RF and the electrical bias energy BE. FIG. 5 is a diagram showing an example of the frequency spectrum of the electrical signal. As shown in FIG. 5, the frequency of the intermodulation distortion component is f RF ±m×f B m is a natural number, 1, 2, 3, ….

[0047] In the plasma processing apparatus 1, one or more signals S are generated from one or more electrical signals acquired in each of the multiple phase periods SP. FI For this purpose, a filter 33, a mixer 34 and a filter 35 are used.

[0048] The filter 33 removes harmonic components from each of the one or more electrical signals. The filter 33 separates one or more signals S from the one or more electrical signals. PF One or more signals S PF Each of the electric signals is input to the mixer 34. Note that each of one or more electric signals may be input to the mixer 34. In this case, the plasma processing apparatus 1 does not need to include the filter 33.

[0049] The mixer 34 receives one or more signals S PF The mixer 34 mixes each of the one or more electrical signals S with a high-frequency signal generated by the oscillator 31g. PFor from one or more electrical signals, one or more mixed signals S MIX One or more mixed signals S MIX Each of the signals S PF or the frequency of the corresponding electrical signal, f RF The mixed signal S is an intermediate frequency signal shifted in the negative direction by MIX At source frequency f RF The corresponding intermediate frequency is 0.

[0050] The filter 35 filters one or more mixed signals S MIX The mutual distortion modulation components are removed from each of the mixed signals S MIX The frequency of the intermodulation distortion components is 0 ± m × f B m is a natural number, 1, 2, 3, 4, 5, . . . The filter 35 filters one or more mixed signals S MIX one or more filtered signals, i.e., one or more signals S FI The center frequency of the passband of the filter 35 is 0. The passband of the filter 35 is a band between the center frequency -Wf / 2 and the center frequency +Wf / 2. Wf is the width of the passband of the filter 35. Wf / 2 is the frequency of f B Wf is smaller than f B It may be smaller than.

[0051] In the plasma processing apparatus 1, each of the multiple phase periods SP, i.e., the phase periods SP n One or more signals S obtained at FIn The impedance matching is performed based on the following: FIn is the phase period SP n One or more signals S at FI where n is an integer between 1 and N. The impedance matching is performed during the phase period SP n In the FIn Alternatively, the signal may be acquired in real time based on one or more signals S acquired within a certain period CY. FIn The impedance matching based on the following is performed during the phase period SP of the following cycle CY: nIn impedance matching, the control unit 36 ​​controls each unit of the plasma processing apparatus 1.

[0052] In one embodiment, the radio frequency power source generates one or more signals S FIn In order to bring the impedance of the load of the high frequency power supply 31 closer to a matching state based on RFn Adjust the source frequency f RFn is designated by the control unit 36 ​​to the oscillator 31g.

[0053] In one embodiment, the phase period SP n In this embodiment, a signal representing the power Pr of the reflected wave is used as the electrical signal in the phase period SP n From the signal Pr representing the power of the reflected wave at FIn Then, the control unit 36 ​​acquires the signal S FIn From phase period SP n For example, the power Pr of the reflected wave in the passband of the filter 35 is calculated. FIn The integral value of the signal intensity during the phase period SP n The reflected wave power Pr is calculated as the reflected wave power Pr at the source frequency f RFn is designated by the control unit 36 ​​to the oscillator 31g.

[0054] In another embodiment, the phase period SP n In this embodiment, a signal representing the power Pr of the reflected wave and a signal representing the power Pf of the forward wave are used as the electrical signals in the phase period SP n The two signals S are obtained by dividing the reflected wave power Pr and the forward wave power Pf. FIn Two signals S FIn The first signal S1 FIn is generated from an electrical signal representing the power of the reflected wave Pr, and two signals S FIn The second signal S2 FIn is generated from an electrical signal representing the power Pf of the traveling wave. Then, the control unit 36 ​​divides the two signals SFIn From phase period SP n For example, the power Pr of the reflected wave and the power Pf of the forward wave in the first signal S1 in the passband of the filter 35 are calculated. FIn The integral value of the signal intensity during the phase period SP n The power Pr of the reflected wave in the pass band of the filter 35 is calculated as the power Pr of the second signal S2 FIn The integral value of the signal intensity during the phase period SP n The power of the reflected wave Pr is calculated as the power Pf of the forward wave at the source frequency f RFn is designated by the control unit 36 ​​to the oscillator 31g.

[0055] In yet another embodiment, during the phase period SP n The electrical signal at voltage V RF and current I RF In this embodiment, a signal representing the phase period SP n Voltage at V RF A signal representing the current I RF Two signals S FIn Two signals S FIn The first signal S1 FIn is the voltage V RF Two signals S are generated from the electrical signal representing FIn The second signal S2 FIn is the current I RF The control unit 36 ​​generates the two signals S FIn From phase period SP n Voltage at V RF , current I RF For example, the first signal S1 in the passband of the filter 35 is FIn The integral value of the signal intensity during the phase period SP n Voltage at V RF In addition, the second signal S2 in the passband of the filter 35 is calculated as follows: FIn The integral value of the signal intensity during the phase period SP n Current IRF And the voltage V RF and current I RF Then, the control unit 36 ​​controls the phase period SP n The impedance of the load of the high frequency power supply 31 at the source frequency f is calculated. Then, the impedance of the load of the high frequency power supply 31 is adjusted so as to approach the matching point. RFn is designated by the control unit 36 ​​to the oscillator 31g.

[0056] In each embodiment, the impedance of the matching circuit of the matching device 31m may be adjusted so that the impedance of the load of the high frequency power supply 31 approaches a matching state.

[0057] In the plasma processing apparatus 1, the source frequency f RF is adjusted in each of a plurality of phase periods SP in the period CY of the electrical bias energy BE. In each of the plurality of phase periods, the electrical signal reflecting the deviation of the impedance of the load of the high frequency power supply 31 from the matched state includes the source frequency f RF Intermodulation distortion components are removed according to the above. Therefore, in the plasma processing apparatus 1 using the high frequency power supply 31 that generates high frequency power RF having a variable frequency in generating plasma, it is possible to remove unnecessary components from the electric signal that reflects the impedance matching state of the load of the high frequency power supply 31. Furthermore, in the plasma processing apparatus 1, impedance matching is performed based on the signal obtained by removing the unnecessary components from the electric signal. Therefore, it is possible to effectively suppress the power of the reflected wave from the high frequency power RF in each of the multiple phase periods.

[0058] Hereinafter, a processing method according to one exemplary embodiment will be described with reference to Fig. 6. Fig. 6 is a flow chart of a processing method according to one exemplary embodiment. The processing method shown in Fig. 6 (hereinafter, referred to as "method MT") can be applied to a plasma processing apparatus 1. To perform method MT, each part of the plasma processing apparatus 1 is controlled by a control unit 2. Method MT is performed in a state where a substrate W to be processed is placed on a substrate support 11.

[0059] The method MT includes a step STa. In the step STa, high-frequency power is supplied from the high-frequency power supply 31 via a matching device 31m to generate plasma from the gas in the chamber 10. During the step STa, the gas supply unit 20 is controlled to supply gas into the chamber 10. During the step STa, the exhaust system 40 is controlled to set the pressure in the chamber 10 to a designated pressure. Also, in the step STa, the high-frequency power supply 31 is controlled to supply high-frequency power RF.

[0060] The method MT further includes a step STb, in which an electric bias energy BE is supplied to a bias electrode of the substrate support 11 to attract ions from the plasma to the substrate W placed on the substrate support 11. In the step STb, the bias power supply 32 is controlled to supply the electric bias energy BE.

[0061] The method MT further includes a step STc, in which one or more electrical signals reflecting deviations of the impedance of the load of the high frequency power supply 31 from a matched state are detected using a sensor (e.g., the directional coupler 31d and / or the sensor 31e). For the one or more electrical signals, please refer to the above description of the plasma processing apparatus 1.

[0062] The method MT further includes a step STd. In the step STd, each of the multiple phase periods SP, i.e., the phase periods SP n A signal that is filtered from one or more electrical signals in, i.e., one or more signals S FIn One or more signals S FIn To generate the signal, the filter 35 is used as described above.

[0063] In the step STa, the phase period SP n The frequency of the radio frequency power RF at RFn In step STd, one or more signals S FIn As mentioned above, during the phase period SPn The intermodulation distortion components of the radio frequency power RF and the electrical bias energy BE are removed from one or more electrical signals in the

[0064] The method MT further comprises a step STe, in which one or more signals S FIn Based on the phase period SP n For details of the impedance matching, please refer to the above description of the plasma processing apparatus 1.

[0065] FIG. 7 is a diagram showing the configuration of another example of a filter that can be employed in a plasma processing apparatus according to an exemplary embodiment. In the plasma processing apparatus 1, a filter 35B shown in FIG. 7 may be used in place of the filter 35. The filter 35B is made up of a plurality (J pieces) of filters 35f1 to 35f having different passbands. J Includes multiple filters 35f1-35f J The center frequencies of the filters 35f1 to 35f2 are the source frequencies that can be set in the high frequency power source 31. J Each passband of the filters 35 is between the center frequency −Wf / 2 and the center frequency +Wf / 2. Wf is the width of the passband of the filter 35. Wf / 2 is the frequency of the filter 35. B Less than.

[0066] The filter 35B further includes a selector 35s. The selector 35s includes a plurality of filters 35f1 to 35f J Of these, phase period SP n Source frequency f at RFn A filter having a center frequency of S is selected, and one or more mixed signals S are input to the selected filter. MIX This allows the phase period SP n In the above, one or more signals S are generated from the selected filter. FIn will be output.

[0067] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0068] In another embodiment, the plasma processing apparatus may be an inductively coupled plasma processing apparatus, an ECR plasma processing apparatus, a helicon wave excited plasma processing apparatus, or a surface wave plasma processing apparatus. In any of the plasma processing apparatuses, high frequency power RF is used to generate plasma.

[0069] Moreover, the plasma processing apparatus 1 includes one set of the filter 33, the mixer 34, and the filter 35 (or the filter 35B). In another embodiment, the plasma processing apparatus may include a plurality of sets of the filter 33, the mixer 34, and the filter 35. The number of sets is the same as the number of electrical signals acquired by the sensor.

[0070] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0071] 1...plasma processing apparatus, 10...chamber, 11...substrate support, 31...high frequency power supply, 31m...matching box, 32...bias power supply, 31d...directional coupler, 31e...sensor, 35...filter.

Claims

1. A chamber; a substrate support disposed within the chamber; a bias power supply configured to supply electrical bias energy to an electrode of the substrate support to draw ions from a plasma generated in the chamber to a substrate placed on the substrate support, the electrical bias energy having a bias frequency that is greater than or equal to 100 kHz and less than or equal to 13.56 MHz, the period of the electrical bias energy being a period of a waveform of the electrical bias energy and having a time length that is the reciprocal of the bias frequency; a matching box having a matching circuit; a radio frequency power supply configured to supply, through the matcher, radio frequency power having a variable frequency to generate the plasma from the gas in the chamber, the radio frequency power supply configured to adjust a frequency of the radio frequency power during each of a plurality of phase periods within the period of the electrical bias energy; a sensor configured to detect an electrical signal reflecting a deviation of the impedance of the load of the high frequency power source from a matched condition; a filter configured to generate a filtered signal by removing intermodulation distortion components of the radio frequency power and the electrical bias energy from the electrical signal in each of the plurality of phase periods; Equipped with The plasma processing apparatus is configured to adjust the frequency of the high frequency power during a same phase period in a second period of the period of the electrical bias energy after the first period based on the filtered signal acquired during each of the multiple phase periods in a first period of the period of the electrical bias energy, so as to bring the impedance of a load of the high frequency power supply closer to a matching state.

2. The plasma processing apparatus of claim 1 , wherein the electrical signal includes a signal representing a voltage and a current measured on a transmission path of the high frequency power.

3. The plasma processing apparatus according to claim 1 , wherein the electrical signal includes a signal representing a power of a reflected wave of the high frequency power from a load.

4. The high frequency power source is an oscillator configured to generate a high frequency signal; an amplifier configured to amplify the radio frequency signal to generate the radio frequency power; Including, The plasma processing apparatus further includes a mixer configured to mix the radio frequency signal and the electrical signal together to generate a mixed signal; the filter is configured to generate the filtered signal from the mixed signal, the filter having a passband whose center frequency is zero, the width of the passband being less than the bias frequency; The plasma processing apparatus according to any one of claims 1 to 3.

5. The plasma processing apparatus according to any one of claims 1 to 3, wherein the filter includes a plurality of filters having different passbands, and is configured to apply to the electrical signal a filter among the plurality of filters whose passband includes the frequency of the high-frequency power in each of the plurality of phase periods.

6. 6. The plasma processing apparatus according to claim 1, wherein the electrical bias energy is a high frequency bias power having the bias frequency.

7. 6. The plasma processing apparatus of claim 1, wherein the electrical bias energy comprises pulses of voltage periodically generated at time intervals having a time length that is the inverse of the bias frequency, or a voltage of any waveform periodically generated.

8. The semiconductor device further includes an upper electrode disposed above the substrate support, the high frequency power supply is electrically connected to the electrode of the substrate support part or the upper electrode via the matching box; The plasma processing apparatus according to any one of claims 1 to 7.

9. a voltage sensor configured to detect a voltage of the electrical bias energy on a transmission path of the electrical bias energy; the high frequency power source is configured to determine the period and the multiple phase periods of the electrical bias energy based on a voltage detected by the voltage sensor. The plasma processing apparatus according to any one of claims 1 to 8.

10. (a) supplying high frequency power from a high frequency power source through a matching box to generate plasma from a gas in a chamber of a plasma processing apparatus, the plasma processing apparatus including a substrate support disposed in the chamber; (b) providing electrical bias energy to an electrode of the substrate support to attract ions from the plasma to a substrate mounted on the substrate support; (c) detecting, with a sensor, an electrical signal reflecting a deviation of the impedance of the load of the high frequency power source from a matched condition; (d) generating a filtered signal from the electrical signal using a filter; Including, the electrical bias energy has a bias frequency that is equal to or greater than 100 kHz and equal to or less than 13.56 MHz, the period of the electrical bias energy being the period of the waveform of the bias energy and having a time length that is the reciprocal of the bias frequency; The frequency of the high frequency power is variable, In the method (a), a frequency of the high frequency power in a same phase period in a second period that is the period of the electrical bias energy after the first period is adjusted based on the filtered signal acquired in each of a plurality of phase periods in a first period that is the period of the electrical bias energy so as to bring an impedance of a load of the high frequency power source closer to a matching state; In (d), the filtered signal is generated by removing intermodulation distortion components of the high frequency power and the electrical bias energy from the electrical signal in each of the plurality of phase periods. Processing methods.

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