Plasma processing apparatus

Abstract

The present invention provides a kind of plasma processing device, the purpose is to control the power of the power with the bandwidth realized by multiple carriers after pulse modulation with high precision.The device includes the power supply unit that can generate the power with bandwidth, the power generated by power supply unit is implemented pulse modulation so that it has high level power and low level power, and, the pulse on time determined by setting pulse frequency and setting duty cycle has the power variation period of the power with bandwidth is long.

Description

Technical Field

[0001] This disclosure relates to plasma processing apparatus. Background Technology

[0002] Patent Document 1 discloses a plasma processing apparatus using microwaves. This plasma processing apparatus includes a microwave output device that outputs microwaves with a certain bandwidth. The microwave output device is capable of controlling the power of the pulse-modulated microwaves.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-36482 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] In the apparatus described in Patent Document 1, there is still room for improvement in order to control the pulse-modulated power of microwaves (electric power, an example of electrical power) having a bandwidth achieved by multiple carrier waves with high precision. This disclosure provides a plasma processing apparatus capable of controlling the pulse-modulated power of electrical power having a bandwidth achieved by multiple carrier waves with high precision.

[0008] Technical means to solve the problem

[0009] One aspect of the present invention provides a plasma processing apparatus. The plasma processing apparatus includes a chamber body and a power supply unit that outputs power for exciting a gas supplied to the chamber body. The power supplied by the power supply unit is microwave, having a center frequency and bandwidth corresponding to a set frequency, a set bandwidth, and a set carrier spacing indicated by a controller, respectively. The power of this power is pulse-modulated such that its pulse frequency, duty cycle, high-level power, and low-level power correspond to the set pulse frequency, set duty cycle, high-level set power, and low-level set power indicated by the controller, respectively. Furthermore, the pulse on-time determined by the set pulse frequency and set duty cycle is longer than the power variation period of the power with bandwidth. The duty cycle is a value obtained by dividing the pulse on-time by the pulse period (pulse on-time + pulse off-time).

[0010] Invention Effects

[0011] By employing various aspects and embodiments of this disclosure, it is possible to control the pulse-modulated power of a power supply with bandwidth achieved by multiple carriers with high precision. Attached Figure Description

[0012] Figure 1This is a diagram illustrating one example of a plasma processing apparatus according to one embodiment.

[0013] Figure 2 This is a diagram illustrating one example of a microwave output device.

[0014] Figure 3 This diagram illustrates the principle of microwave generation in the waveform generator.

[0015] Figure 4 This is an example of microwave power modulated by pulses.

[0016] Figure 5 This is a diagram illustrating one example of microwaves with different carrier spacing.

[0017] Figure 6 This is an example of a synchronization signal used for pulse modulation of microwaves.

[0018] Figure 7 This is a diagram illustrating one example of a structure related to microwave power feedback.

[0019] Figure 8 This is a diagram illustrating another example of a structure related to microwave power feedback.

[0020] Figure 9 This is a diagram showing the first example of a detailed structure related to power feedback in a microwave output device.

[0021] Figure 10 This is a second example of a detailed structure related to the power feedback of a microwave output device.

[0022] Figure 11 This is an example of a microwave (pulseless modulation) waveform with bandwidth achieved by multiple carriers.

[0023] Figure 12 It is based on the BB cycle. Figure 11 The image shows an example of a waveform obtained by averaging microwaves.

[0024] Figure 13 It is an example of a moving average of microwave (pulse-free modulation) power with bandwidth achieved by multiple carriers.

[0025] Figure 14 This is an example of a detector output with a bandwidth achieved by multiple carriers (carrier spacing 10kHz, with pulse modulation).

[0026] Figure 15 It is a table summarizing the power measurement results of microwaves (carrier spacing 10kHz, with pulse modulation) with bandwidth realized by multiple carriers.

[0027] Figure 16 This is a table representing one example of the pulse ON time.

[0028] Figure 17 This is a table representing one example of carrier spacing, BB period, and pulse ON time.

[0029] Figure 18 This is an example of a detector output with a bandwidth achieved by multiple carriers (carrier spacing 500.1 kHz, with pulse modulation).

[0030] Figure 19 This table summarizes the power measurements of microwaves with bandwidth achieved by multiple carriers (carrier spacing 500.1 kHz, with pulse modulation).

[0031] Figure 20 This is a diagram illustrating another example of a structure related to microwave power feedback.

[0032] Figure 21 This is a diagram illustrating the timing of the pulse ON signal and the BB cycle. Detailed Implementation

[0033] The following describes various illustrative implementation methods.

[0034] One aspect of the present invention provides a plasma processing apparatus. The plasma processing apparatus includes a chamber body and a microwave output device that outputs microwaves for exciting a gas supplied to the chamber body. The microwave output device includes a microwave generator, an output unit, a first directional coupler, and a measuring unit. The microwaves generated by the microwave generator have a center frequency and bandwidth corresponding to a set frequency, a set bandwidth, and a set carrier spacing indicated by a controller, respectively. The power of the microwaves is pulse-modulated such that their pulse frequency, duty cycle, high level power, and low level power correspond to the set pulse frequency, set duty cycle, high level set power, and low level set power indicated by the controller, respectively. The duty cycle is a value obtained by dividing the pulse ON time (pulse on-time) by the pulse period (pulse ON time + pulse OFF time (pulse off-time)). The output unit outputs microwaves propagating from the microwave generator. The first directional coupler outputs a portion of a traveling wave propagating from the microwave generator to the output unit. The measurement unit determines a first high measurement value and a first low measurement value, representing the high and low power levels of the traveling wave output from the first directional coupler, respectively. The pulse ON time, determined by the set pulse frequency and set duty cycle, is longer than the power variation period of the microwave with bandwidth. The microwave generator averages the first high measurement value and the first low measurement value according to a predetermined moving average time and a predetermined sampling interval. Based on the averaged first high measurement value and the set power for the high level, the microwave generator controls the high-level power of the pulse-modulated microwave, and based on the averaged first low measurement value and the set power for the low level, it controls the low-level power of the pulse-modulated microwave.

[0035] In this plasma processing apparatus, the power of microwaves with a bandwidth achieved by multi-carrier pulse modulation is performed. Specifically, the high-level power of the pulse-modulated microwaves is controlled based on an averaged first high measured value and a high-level set power. Furthermore, the low-level power of the pulse-modulated microwaves is controlled based on an averaged first low measured value and a low-level set power. Thus, by pulse-modulating the microwave power and controlling the high and low levels of power based on the set power, the pulse-modulated power of microwaves with a bandwidth achieved by multi-carrier pulse modulation can be controlled. Moreover, by satisfying the condition that "the pulse ON time, determined by the set pulse frequency and set duty cycle, is longer than the power fluctuation period of the microwave with bandwidth," the waveform of the high-level power can be extracted and appropriately averaged. Therefore, power fluctuations (differences from the set power) can be suppressed. As a result, this apparatus can control the power of pulse-modulated microwaves with bandwidth with high precision.

[0036] In one embodiment, the microwave output device may further include a second directional coupler that outputs a portion of the reflected wave returning to the output unit. Based on the portion of the reflected wave output from the second directional coupler, the measurement unit further determines a second high measurement value and a second low measurement value, representing high and low power levels of the reflected wave in the output unit, respectively. The microwave generating unit averages the second high measurement value and the second low measurement value according to a predetermined moving average time and a predetermined sampling interval. Based on the averaged first high measurement value, the averaged second high measurement value, and a set power for the high level, the unit controls the high-level power of the pulse-modulated microwave, and based on the averaged first low measurement value, the averaged second low measurement value, and a set power for the low level, the unit controls the low-level power of the pulse-modulated microwave.

[0037] By employing this structure, the plasma processing device can achieve power control based on the power of the reflected wave. Furthermore, even with the power of the reflected wave, the plasma processing device can extract the waveform of a high-level power and appropriately average it.

[0038] In one implementation, the pulse low time, determined by a set pulse frequency and a set duty cycle, can be longer than the power variation period of a microwave with bandwidth.

[0039] In one implementation, the low level can be 0. In this case, the plasma processing device is able to extract the waveform of the power under ON / OFF control for appropriate averaging.

[0040] Various embodiments will now be described in detail with reference to the accompanying drawings. In the drawings, the same or equivalent parts are labeled with the same reference numerals.

[0041] [Plasma Processing Device]

[0042] Figure 1 This is a diagram illustrating a plasma processing apparatus according to one embodiment. (See diagram below.) Figure 1 As shown, the plasma processing apparatus 1 includes a chamber body 12 and a microwave output device 16. The plasma processing apparatus 1 may also include a stage 14, an antenna 18, and a dielectric window 20.

[0043] The chamber body 12 provides a processing space S within it. The chamber body 12 has a side wall 12a and a bottom 12b. The side wall 12a is formed in a generally cylindrical shape. The central axis of the side wall 12a is approximately aligned with an axis Z extending in the vertical direction. The bottom 12b is located at the lower end of the side wall 12a. An exhaust port 12h for venting is provided at the bottom 12b. In addition, the upper end of the side wall 12a is open.

[0044] A dielectric window 20 is provided on the upper end of the side wall 12a. The dielectric window 20 has a lower surface 20a opposite to the processing space S. The dielectric window 20 closes the opening at the upper end of the side wall 12a. An O-ring 19 is provided between the dielectric window 20 and the upper end of the side wall 12a. The O-ring 19 reliably seals the chamber body 12.

[0045] The stage 14 is housed within the processing space S. The stage 14 is positioned so as to face the dielectric window 20 in the vertical direction. Furthermore, the stage 14 is positioned such that the processing space S is located between the dielectric window 20 and the stage 14. The stage 14 is configured to support the workpiece WP (e.g., a wafer) placed thereon.

[0046] In one embodiment, the stage 14 includes a base 14a and an electrostatic chuck 14c. The base 14a has a generally disc-shaped form and is made of a conductive material such as aluminum. The central axis of the base 14a is approximately aligned with axis Z. The base 14a is supported by a cylindrical support 48. The cylindrical support 48 is made of an insulating material and extends vertically upward from the bottom 12b. A conductive cylindrical support 50 is provided on the outer periphery of the cylindrical support 48. The cylindrical support 50 extends vertically upward from the bottom 12b of the chamber body 12 along the outer periphery of the cylindrical support 48. An annular exhaust path 51 is formed between the cylindrical support 50 and the sidewall 12a.

[0047] A baffle 52 is provided at the upper part of the exhaust path 51. The baffle 52 has an annular shape. The baffle 52 has a plurality of through holes extending through it in the thickness direction. The aforementioned exhaust port 12h is provided below the baffle 52. The exhaust port 12h is connected to the exhaust device 56 via an exhaust pipe 54. The exhaust device 56 has a vacuum pump such as an automatic pressure control valve (APC) and a turbomolecular pump. The exhaust device 56 can reduce the pressure of the processing space S to the desired vacuum level.

[0048] The base 14a also serves as a high-frequency electrode. The base 14a is electrically connected to a high-frequency power supply 58 for high-frequency bias via a power supply rod 62 and a matching unit 60. The high-frequency power supply 58 outputs high-frequency power at a set power level, suitable for controlling the energy of ions attracted to the workpiece WP, at a specific frequency, for example, 13.56 MHz.

[0049] Furthermore, the high-frequency power supply 58 may also include a pulse generator that applies high-frequency power (RF power) to the base 14a after pulse modulation. In this case, the high-frequency power supply 58 performs pulse modulation in a manner that periodically alternates between high-level and low-level power in the high-frequency power. The high-frequency power supply 58 performs pulse adjustment based on a synchronization signal PSS-R generated by the pulse generator. The synchronization signal PSS-R is a signal used to determine the period and duty cycle of the high-frequency power. As an example of the settings during pulse modulation, the pulse frequency is 10Hz to 250kHz, and the pulse duty cycle (the ratio of high-level power time to the pulse period) is 10% to 90%.

[0050] Matching unit 60 includes a matching device for achieving impedance matching between the high-frequency power supply 58 side and the load side, where the load is mainly an electrode, plasma, chamber body 12, etc. The matching device includes a blocking capacitor for generating a self-bias voltage. Matching unit 60 operates based on the synchronization signal PSS-R to achieve matching when the high-frequency power is pulse-modulated.

[0051] An electrostatic chuck 14c is provided on the upper surface of the base 14a. The electrostatic chuck 14c holds the workpiece WP by electrostatic attraction. The electrostatic chuck 14c includes an electrode 14d, an insulating film 14e, and an insulating film 14f, and is generally disk-shaped. The central axis of the electrostatic chuck 14c is approximately aligned with the axis Z. The electrode 14d of the electrostatic chuck 14c is made of a conductive film and is disposed between the insulating films 14e and 14f. The electrode 14d is electrically connected to a DC power supply 64 via a switch 66 and a covering wire 68. The electrostatic chuck 14c can hold the workpiece WP by the Coulomb force generated by the DC voltage applied from the DC power supply 64. In addition, a focusing ring 14b is provided on the base 14a. The focusing ring 14b is configured to surround the workpiece WP and the electrostatic chuck 14c.

[0052] A cooling medium chamber 14g is provided inside the base 14a. The cooling medium chamber 14g is formed, for example, extending around the axis Z. Cooling medium from the refrigeration unit is supplied to the cooling medium chamber 14g via piping 70. The cooling medium supplied to the cooling medium chamber 14g returns to the refrigeration unit via piping 72. By controlling the temperature of the cooling medium using the refrigeration unit, the temperature of the electrostatic chuck 14c and even the workpiece WP are controlled.

[0053] A gas supply line 74 is also formed on the stage 14. This gas supply line 74 is provided for supplying heat transfer gas, such as He gas, between the upper surface of the electrostatic chuck 14c and the back surface of the workpiece WP.

[0054] The microwave output device 16 outputs microwaves to excite the processing gas supplied to the chamber body 12. The microwave output device 16 is configured to variably adjust the frequency, power, and bandwidth of the microwaves. The microwave output device 16 can generate microwaves of a single frequency, for example, by setting the microwave bandwidth to approximately 0. Alternatively, the microwave output device 16 can generate microwaves with a certain bandwidth, including multiple frequency components. The power of these multiple frequency components can be the same, or only the center frequency component within the band can have a higher power than the other frequency components. In one example, the microwave output device 16 can adjust the microwave power within the range of 0W to 5000W. The microwave output device 16 can adjust the microwave frequency or center frequency within the range of 2400MHz to 2500MHz. The microwave output device 16 can adjust the microwave bandwidth within the range of 0MHz to 100MHz. Furthermore, the microwave output device 16 can adjust the frequency spacing (carrier spacing) of the multiple frequency components of the microwaves within the band within the range of 0 to 1MHz.

[0055] The microwave output device 16 may also include a pulse generator that pulse-modulates the microwave power before outputting it. In this case, the microwave output device 16 pulse-modulates the microwave in such a way that high-level power and low-level power in the microwave power periodically repeat. The microwave output device 16 performs pulse adjustment based on a synchronization signal PSS-M generated by the pulse generator. The synchronization signal PSS-M is a signal used to determine the period and duty cycle of the microwave power. As an example of the settings for pulse modulation, the pulse frequency is 1Hz to 20kHz, and the pulse duty cycle (the ratio of high-level power time to pulse period) is 10% to 90%. The microwave output device 16 may also pulse-modulate the microwave power in a manner synchronized with the pulse-modulated high-frequency power output from the high-frequency power supply 58.

[0056] The plasma processing apparatus 1 also includes a waveguide 21, a tuner 26, a mode converter 27, and a coaxial waveguide 28. The output of the microwave output device 16 is connected to one end of the waveguide 21. The other end of the waveguide 21 is connected to the mode converter 27. The waveguide 21 is, for example, a rectangular waveguide. The tuner 26 is disposed within the waveguide 21. The tuner 26 has stubs 26a, 26b, and 26c. The stubs 26a, 26b, and 26c are configured to adjust their protrusion relative to the internal space of the waveguide 21. By adjusting the protrusion positions of the stubs 26a, 26b, and 26c relative to a reference position, the tuner 26 matches the impedance of the microwave output device 16 with the impedance of the load, such as the impedance of the chamber body 12.

[0057] Mode converter 27 converts the mode of microwaves from waveguide 21 and supplies the mode-converted microwaves to coaxial waveguide 28. Coaxial waveguide 28 includes an outer conductor 28a and an inner conductor 28b. The outer conductor 28a has a generally cylindrical shape, with its central axis approximately aligned with axis Z. The inner conductor 28b has a generally cylindrical shape and extends inside the outer conductor 28a. The central axis of the inner conductor 28b is also approximately aligned with axis Z. The coaxial waveguide 28 transmits the microwaves from mode converter 27 to antenna 18.

[0058] Antenna 18 is disposed on surface 20b of dielectric window 20, opposite to the lower surface 20a. Antenna 18 includes slot plate 30, dielectric plate 32 and cooling jacket 34.

[0059] A slit plate 30 is disposed on the surface 20b of the dielectric window 20. The slit plate 30 is formed of a conductive metal and has a generally disc-shaped form. The central axis of the slit plate 30 is approximately aligned with the axis Z. A plurality of slit holes 30a are formed on the slit plate 30. In one example, the plurality of slit holes 30a constitute a plurality of slit pairs. Each slit pair comprises two slit holes 30a in a generally elongated shape extending in directions intersecting each other. The plurality of slit pairs are arranged along one or more concentric circles about the axis Z. Additionally, a through hole 30d, through which the guide tube 36 (described later) can pass, is formed in the central portion of the slit plate 30.

[0060] A dielectric plate 32 is disposed on the slot plate 30. The dielectric plate 32 is formed of a dielectric material such as quartz and is approximately disk-shaped. The central axis of the dielectric plate 32 is approximately aligned with the axis Z. A cooling sleeve 34 is disposed on the dielectric plate 32. The dielectric plate 32 is disposed between the cooling sleeve 34 and the slot plate 30.

[0061] The surface of the cooling jacket 34 is conductive. A flow path 34a is formed inside the cooling jacket 34. It is configured to supply a cooling medium to the flow path 34a. The upper surface of the cooling jacket 34 is electrically connected to the lower end of the outer conductor 28a. In addition, the lower end of the inner conductor 28b passes through a hole formed in the central portion of the cooling jacket 34 and the dielectric plate 32 and is electrically connected to the slot plate 30.

[0062] Microwaves from the coaxial waveguide 28 propagate within the dielectric plate 32 and are supplied to the dielectric window 20 through multiple slit holes 30a of the slit plate 30. The microwaves supplied to the dielectric window 20 are then directed into the processing space S.

[0063] The conduit 36 ​​passes through the inner bore of the inner conductor 28b of the coaxial waveguide 28. Additionally, as described above, a through hole 30d is formed in the center of the slit plate 30, through which the conduit 36 ​​can pass. The conduit 36 ​​extends through the inner bore of the inner conductor 28b and connects to the gas supply system 38.

[0064] The gas supply system 38 supplies processing gas for treating the workpiece WP to the conduit 36. The gas supply system 38 may include a gas source 38a, a valve 38b, and a flow controller 38c. The gas source 38a is the source of the processing gas. The valve 38b switches the supply of processing gas from the gas source 38a on and off. The flow controller 38c, for example, is a mass flow controller used to adjust the flow rate of the processing gas from the gas source 38a.

[0065] The plasma processing apparatus 1 may further include an ejector 41. The ejector 41 supplies gas from the conduit 36 ​​into the through-hole 20h formed in the dielectric window 20. The gas supplied to the through-hole 20h of the dielectric window 20 is then supplied to the processing space S. The processing gas is then excited by microwaves introduced from the dielectric window 20 into the processing space S. As a result, plasma is generated within the processing space S, and the workpiece WP is processed using active substances such as ions and / or free radicals from this plasma.

[0066] The plasma processing apparatus 1 also includes a controller 100. The controller 100 provides unified control over all parts of the plasma processing apparatus 1. The controller 100 may include a processor such as a CPU, a user interface, and a storage unit.

[0067] The processor controls the microwave output device 16, the stage 14, the gas supply system 38, the exhaust device 56, and other components by executing the programs and process plans stored in the storage unit.

[0068] The user interface includes a keyboard or touch panel, a display, etc. The keyboard or touch panel is used by the process manager to input commands to manage the plasma processing device 1, and the display is used to visually display the operating status of the plasma processing device 1.

[0069] The storage unit contains control programs (software) for implementing various processes executed by the plasma processing apparatus 1 under the control of the processor, as well as process plans including processing condition data. The processor, according to instructions from the user interface, calls and executes various control programs from the storage unit as needed. Under the control of this processor, the desired processes are executed in the plasma processing apparatus 1.

[0070] [Structural Example of Microwave Output Device 16]

[0071] Figure 2 This diagram illustrates an example of a microwave output device. (For example...) Figure 2 As shown, the microwave output device 16 is connected to the computing device 100a, which includes a controller 100 and a waveform generator 161.

[0072] Waveform generator 161 generates microwave waveforms. The microwave waveforms generated by waveform generator 161 have a center frequency and bandwidth corresponding to the set frequency and set bandwidth specified by controller 100, respectively. Waveform generator 161 outputs the microwave waveforms to microwave output device 16.

[0073] The microwave output device 16 pulse-modulates the waveform of the microwave generated by the waveform generator 161 according to the settings of the controller 100, and outputs it as microwave. The microwave output device 16 includes a microwave generator 16a, a waveguide 16b, a circulator 16c, waveguides 16d and 16e, a first directional coupler 16f, a second directional coupler 16h, a measurement unit 16k (an example of a measurement unit), and a virtual load 16j.

[0074] The microwave generator 16a generates microwaves with pulsed power modulation. This pulse modulation gives the microwaves a pulse frequency, duty cycle, high-level power, and low-level power corresponding to the set values ​​indicated by the controller 100. The set values ​​include the pulse frequency, set duty cycle, high-level set power, and low-level set power.

[0075] The microwave generator 16a includes a power control unit 162, an attenuator 163, an amplifier 164, an amplifier 165, and a mode converter 166.

[0076] Waveform generator 161 is connected to attenuator 163. As an example, attenuator 163 is a device capable of changing the attenuation amount (attenuation rate) according to the applied voltage value. Attenuator 163 is connected to power control unit 162. Power control unit 162 uses the applied voltage value to control the attenuation rate (attenuation amount) of the microwave in attenuator 163. Power control unit 162 controls the attenuation rate (attenuation amount) of the microwave in attenuator 163 so that the microwave output by waveform generator 161 becomes microwave with power corresponding to a set value. The set value includes the pulse frequency, set duty cycle, high level set power, and low level set power indicated by controller 100.

[0077] As an example, the power control unit 162 includes a control unit 162a and a pulse generator 162b. The control unit 162a may be a processor. The control unit 162a obtains a setting profile from the controller 100. The control unit 162a outputs the information required for pulse modulation (pulse frequency and duty cycle) from the setting profile to the pulse generator 162b. The pulse generator 162b generates a synchronization signal PSS-M based on the obtained information. The control unit 162a determines the microwave attenuation rate (attenuation amount) based on the synchronization signal PSS-M and the setting profile set by the controller 100.

[0078] The control unit 162a can also acquire the synchronization signal PSS-R generated by the pulse generator 58a of the high-frequency power supply 58. The pulse generator 162b can generate a synchronization signal PSS-M that is synchronized with the synchronization signal PSS-R. In this case, the pulse modulation of microwave power and the pulse modulation of high-frequency power can be synchronized.

[0079] The output of attenuator 163 is connected to mode converter 166 via amplifiers 164 and 165. Amplifiers 164 and 165 amplify the microwaves at a predetermined amplification rate. Mode converter 166 converts the propagation mode of the microwaves output from amplifier 165 from TEM to TE01. The output microwaves of microwave generator 16a are the microwaves generated by the mode conversion in mode converter 166.

[0080] The output of microwave generator 16a is connected to one end of waveguide 16b. The other end of waveguide 16b is connected to the first port 261 of circulator 16c. Circulator 16c has a first port 261, a second port 262A, and a third port 263A. Circulator 16c outputs microwaves input to the first port 261 from the second port 262A and outputs microwaves input to the second port 262A from the third port 263A. The second port 262A of circulator 16c is connected to one end of waveguide 16d. The other end of waveguide 16d is the output section 16t of microwave output device 16.

[0081] The third port 263A of the circulator 16c is connected to one end of the waveguide 16e. The other end of the waveguide 16e is connected to the dummy load 16j. The dummy load 16j receives and absorbs the microwaves propagating in the waveguide 16e. The dummy load 16j, for example, converts the microwaves into heat.

[0082] A first directional coupler 16f is disposed between one end and the other end of the waveguide 16b. The first directional coupler 16f is configured to branch a portion of the microwave (i.e., traveling wave) that is output from the microwave generator 16a and propagates toward the output unit 16t, and output a portion of the traveling wave.

[0083] The second directional coupler 16h is disposed between one end and the other end of the waveguide 16e. The second directional coupler 16h is configured to branch a portion of the reflected wave transmitted to the third port 263A of the circulator 16c and output a portion of the reflected wave for the microwave (i.e., the reflected wave) returning to the output section 16t.

[0084] The measurement unit 16k determines a first high measurement value pf(H) and a first low measurement value pf(L), representing the high and low power levels of the traveling wave output from the first directional coupler 16f, respectively. Additionally, the measurement unit 16k determines a second high measurement value pr(H) and a second low measurement value pr(L), representing the high and low power levels of the reflected wave output from the second directional coupler 16h, respectively.

[0085] The measuring unit 16k is connected to the power control unit 162. The measuring unit 16k outputs the measured value to the power control unit 162. The power control unit 162 controls the attenuator 163 so that the difference between the measured values ​​of the traveling wave and the reflected wave, i.e., the load power (effective power), is consistent with the set power specified by the controller 100 (power feedback control).

[0086] Tuner 26 includes a tuner control unit 260. The tuner control unit 260 adjusts the protruding positions of stubs 26a, 26b, and 26c based on signals from the controller 100, so that the impedance on the microwave output device 16 side matches the impedance on the antenna 18 side. The tuner control unit 260 uses a drive circuit and actuator (not shown) to operate the stubs 26a, 26b, and 26c.

[0087] The tuner control unit 260 can also obtain at least one of the microwave power synchronization signal PSS-M generated by the pulse generator 162b and the high-frequency power synchronization signal PSS-R generated by the pulse generator 58a of the high-frequency power supply 58. For example, the tuner control unit 260 obtains the synchronization signal PSS-M from the control unit 162a. The tuner control unit 260 can obtain the synchronization signal PSS-R from the control unit 162a or directly from the pulse generator 58a of the high-frequency power supply 58. The tuner control unit 260 can operate the stubs 26a, 26b, and 26c with consideration of the synchronization signal.

[0088] [Details of the waveform generation section]

[0089] Figure 3 This diagram illustrates the principle of microwave generation in the waveform generator. (For example...) Figure 3As shown, waveform generator 161 includes, for example, a PLL (Phase Locked Loop) oscillator and an IQ digital modulator connected to the PLL oscillator, wherein the PLL oscillator is capable of oscillating to generate microwaves with a phase synchronized with a reference frequency. Waveform generator 161 sets the frequency of the microwaves oscillating in the PLL oscillator to a set frequency specified by controller 100. Furthermore, waveform generator 161 uses the IQ digital modulator to modulate the microwaves from the PLL oscillator and microwaves having a 90° phase difference with the microwaves from the PLL oscillator. Thus, waveform generator 161 generates microwaves with multiple frequency components within a frequency band, or generates microwaves of a single frequency.

[0090] Waveform generator 161 can generate microwaves with multiple frequency components by generating a continuous signal through inverse discrete Fourier transform of N complex data symbols. The method for generating this signal can be the same as the OFDMA (Orthogonal Frequency-Division Multiple Access) modulation method used in digital television broadcasting, etc. (see, for example, Japanese Patent No. 5320260).

[0091] In one example, waveform generator 161 has waveform data represented as a sequence of pre-digitized codes. Waveform generator 161 quantizes the waveform data and applies an inverse Fourier transform to the quantized data to generate I and Q data. Then, waveform generator 161 applies a digital-to-analog (D / A) converter to the I and Q data respectively, obtaining two analog signals. Waveform generator 161 inputs this analog signal to an LPF (low-pass filter) that allows only low-frequency components to pass. Waveform generator 161 mixes the two analog signals output from the LPF with microwaves from a PLL oscillator and microwaves with a 90° phase difference from the microwaves from the PLL oscillator, respectively. Next, waveform generator 161 synthesizes the microwaves generated through mixing. Thus, waveform generator 161 generates microwaves with one or more frequency components.

[0092] [An example of microwave technology]

[0093] The microwave power output from the microwave generator 16a is modulated into a pulsed waveform, in which high-level power and low-level power alternate. Figure 4 This is an example of microwave power modulated by pulses. For example... Figure 4As shown, the microwave has a center frequency, bandwidth, and carrier spacing corresponding to the set frequency, set bandwidth, and set carrier spacing indicated by the controller 100, respectively. The microwave also has a pulse frequency, duty cycle, high-level power, and low-level power corresponding to the set values ​​indicated by the controller 100. The set values ​​include the pulse frequency, set duty cycle, high-level set power, and low-level set power. Low-level power is power lower than high-level power. Low-level power can be higher than the minimum power required to maintain the plasma generation state, or it can be 0. One waveform of the microwave is called a carrier wave. The carrier spacing is the interval between carrier waves, and the reciprocal of the carrier spacing is the longest period of power variation in a microwave with bandwidth.

[0094] Figure 5 (A) and (B) are examples of microwaves with different carrier spacing. Figure 5 (A) is a microwave with a set frequency of 2460MHz, a set bandwidth of 10MHz, and a set carrier spacing of 10kHz. The number of carriers can be obtained by dividing the set bandwidth by the set carrier spacing and adding 1. Here, the number of carriers is 1001. Figure 5 (B) is a microwave with a set frequency of 2460MHz, a set bandwidth of 10.1MHz, and a carrier spacing of 10.1kHz. The number of carriers is 1001. For example... Figure 5 As shown in (A) and (B), the power of any microwave is 1500W. That is, even with the same power, the carrier spacing and the set bandwidth can be set to different values.

[0095] [An example of a microwave synchronization signal]

[0096] Figure 6 This is an example of a synchronization signal used for pulse modulation of microwaves. For example... Figure 6 As shown, the synchronization signal PSS-M is a pulse signal that alternates between an ON state (high level) and an OFF state (low level). The pulse period PT1 of the synchronization signal PSS-M is defined by the interval between the moments when it reaches a high level. If the difference between the high and low levels is Δ, then the high-level time HT is defined as the period from the moment when 0.5Δ is reached during the rise period PU of the pulse to the moment when 0.5Δ is reached during the fall period PD of the pulse. The ratio of the high-level time HT to the pulse period PT1 is the duty cycle. The pulse generator 162b generates a pulse signal based on the pulse frequency (1 / PT1) and duty cycle (HT / PT1×100[%) specified by the controller 100, as shown. Figure 6 The synchronization signal shown.

[0097] [An example of power feedback]

[0098] Figure 7This is a diagram illustrating one example of a structure related to microwave power feedback. (Example) Figure 7 As shown, power feedback is achieved through the measurement unit 16k, the control unit 162a, and the attenuator 163.

[0099] like Figure 7 As shown, waveform generator 161 outputs microwaves with bandwidth achieved by multi-carrier operation. Control unit 162a and attenuator 163 pulse-modulate the bandwidth-bound microwaves. Microwave generator 16a outputs pulse-modulated microwaves. Measurement unit 16k measures the power of the traveling wave and reflected wave of the microwaves and outputs it to control unit 162a. Control unit 162a provides power feedback in such a way that the difference between the detected power value of the traveling wave and the detected power value of the reflected wave becomes a set value. Through such a feedback loop, the set value specified by controller 100 is achieved.

[0100] Here, when the microwave power is pulse-modulated, except when the low-level power is set to 0, separate feedback control is required for the high-level and low-level power. Specifically, the measurement unit 16k measures the first high measurement value pf(H), the first low measurement value pf(L), the second high measurement value pr(H), and the second low measurement value pr(L), and outputs the measurement results to the control unit 162a. The control unit 162a switches between high-level power feedback and low-level power feedback based on the synchronization signal PSS-M.

[0101] When providing feedback at a high power level, control unit 162a controls the high power level of the pulse-modulated microwave based on a first high measurement value pf(H), a second high measurement value pr(H), and a high-level set power. When providing feedback at a low power level, control unit 162a controls the low power level of the pulse-modulated microwave based on a first low measurement value pf(L), a second low measurement value pr(L), and a low-level set power.

[0102] More specifically, when providing feedback at a high level of power, control unit 162a controls the difference between the first high measured value pf(H) and the second high measured value pr(H). Control unit 162a controls the high-level power of the microwaves output from microwave output device 16 so that the difference is close to the set high power specified by controller 100. Similarly, when providing feedback at a low level of power, control unit 162a controls the difference between the first low measured value pf(L) and the second low measured value pr(L). Control unit 162a controls the low-level power of the microwaves output from microwave output device 16 so that the difference is close to the set low power specified by controller 100. This allows the load power of the microwaves supplied to the load coupled to output unit 16t to approach the set power. Furthermore, when the low-level power is set to 0, only high-level power feedback is required.

[0103] [Switching of feedback control modes]

[0104] The control unit 162a can also change the feedback operation according to the control mode. The control mode can be specified by the controller 100. For example, when the control mode indicated by the controller 100 is PL mode, the control unit 162a controls the microwave power using the power difference between the traveling wave and the reflected wave, as described above. When the control mode indicated by the controller 100 is Pf mode, the control unit 162a controls the microwave power using only the power of the traveling wave. As a more specific example, when the control mode indicated by the controller 100 is Pf mode, the control unit 162a operates as follows: The control unit 162a controls the high-level power of the pulse-modulated microwave in a manner that makes the first high measurement value pf(H) close to the high-level set power. And, the control unit 162a controls the low-level power of the pulse-modulated microwave in a manner that makes the first low measurement value pf(L) close to the low-level set power.

[0105] [Relationship between synchronization signals for microwave power and high-frequency power]

[0106] Both microwave power and high-frequency power are pulse-controlled. Figure 7 In the structure shown, the high-frequency power synchronization signal PSS-R is not input to the control unit 162a. Furthermore, the microwave synchronization signal PSS-M is not input to the high-frequency power supply 58. Therefore, the microwave power is not synchronized with the high-frequency power.

[0107] In one implementation, the microwave power can also be synchronized with the high-frequency power. In this case, the effect of pulse modulation of the high-frequency power on the reflected microwave wave can be reduced. Figure 8 This is another example of a structure related to microwave power feedback. (And...) Figure 7 Compared to the asynchronous power feedback structure shown, another example differs in that the microwaves generated by the microwave output device are pulse-modulated microwaves that are synchronized with the high-frequency power; otherwise, they are the same. The pulse generator 58a of the high-frequency power supply 58 outputs a synchronization signal PSS-R for the high-frequency power to the control unit 162a. The control unit 162a outputs a synchronization trigger to the pulse generator 162b for synchronization with the synchronization signal PSS-R. The pulse generator 162b generates a synchronization signal PSS-M for the microwave power synchronized with the synchronization signal PSS-R based on the synchronization trigger. The control unit 162a uses the synchronization signal PSS-M to control the attenuator 163. Thus, microwaves that are pulse-modulated with the power in a manner synchronized with the high-frequency power can be output.

[0108] [Detailed structure related to power feedback]

[0109] [First example of a detailed structure]

[0110] Figure 9 This is a diagram illustrating the first example of a detailed structure related to the power feedback of a microwave output device. (See diagram for example.) Figure 9 As shown, the control unit 162a of the microwave generator 16a obtains a setting configuration file from the controller 100. The setting configuration file includes at least a high-level setting power PfH, a low-level setting power PfL, a setting pulse frequency, a duty cycle, and a synchronization number. The synchronization number is an identifier used to select the synchronization category. For example, identifier "1" indicates that the time when the microwave power is at a high level is synchronized with the time when the high-frequency power is at a high level. Identifier "2" indicates that the time when the microwave power is at a low level is synchronized with the time when the high-frequency power is at a low level. Without a specified synchronization number, the microwave synchronization signal is not synchronized with the high-frequency synchronization signal. Alternatively, one of the synchronization numbers can be assigned to "asynchronous". The setting configuration file may also include settings for the center frequency, modulation waveform, setting carrier spacing, and PL / Pf mode. The modulation waveform is the setting bandwidth. The control unit 162a outputs the pulse frequency and duty cycle obtained from the controller 100 to the pulse generator 162b.

[0111] Control unit 162a includes a pulse input device 167a. Control unit 162a acquires a high-frequency power synchronization signal PSS-R via pulse input device 167a. Control unit 162a generates a synchronization trigger based on the synchronization signal PSS-R and a synchronization number. Furthermore, control unit 162a may not generate a synchronization trigger if no synchronization number is specified. Control unit 162a includes a pulse output device 167d. Control unit 162a outputs the synchronization trigger to pulse generator 162b via pulse output device 167d.

[0112] The pulse generator 162b generates a microwave synchronization signal PSS-M based on the pulse frequency, duty cycle, and synchronous triggering. The pulse generator 162b generates the microwave synchronization signal PSS-M based on the pulse frequency and duty cycle even when the microwave synchronization signal is not synchronized with the high-frequency synchronization signal.

[0113] The control unit 162a determines the applied voltage value to the attenuator 163 based on the synchronization signal PSS-M. The control unit 162a outputs the applied voltage value to the D / A converter 167f. The D / A converter 167f converts the digital signal of the output (set) voltage value into an analog signal. The control unit 162a applies voltage to the attenuator 163 via the D / A converter 167f. Thus, pulse-modulated microwaves can be output from the microwave generator 16a.

[0114] The measurement unit 16k outputs the traveling wave power and reflected wave power of the microwaves output from the first directional coupler 16f and the second directional coupler 16h as measured values ​​pf for traveling wave power and pr for reflected wave power.

[0115] The control unit 162a includes A / D converters 167b and 167c that convert analog signals into digital signals. The control unit 162a obtains the measured value pf of the traveling wave power and the measured value pr of the reflected wave power from the measurement unit 16k via the A / D converters 167b and 167c.

[0116] The control unit 162a is configured to refer to the storage unit 162c. The control unit 162a can refer to the definition data DA1 stored in the storage unit 162c to determine the data to be obtained from the measured values ​​(pf, pr). The definition data DA1, for example, contains a masking rule (filter / selection scheme) that limits the sampling period of the data points. The definition data DA1 is, for example, internally set by the control unit 162a and pre-stored in the storage unit 162c.

[0117] The control unit 162a refers to the definition data DA1. The control unit 162a detects the high-level measurement value pfH and the low-level measurement value pfL included in the measured power value pf of the traveling wave. Furthermore, the control unit 162a detects the high-level measurement value prH and the low-level measurement value prL included in the measured power value pr of the reflected wave. As an example, the definition data DA1 includes a definition that specifies that during the H-detection shielding time (first shielding period) from the moment it becomes high-level until a predetermined time has elapsed, the high-level measurement values ​​(pfH, prH) cannot be sampled. As an example, the definition data DA1 includes a definition that specifies that during the L-detection shielding time (second shielding period) from the moment it becomes low-level until a predetermined time has elapsed, the low-level measurement values ​​(pfL, prL) cannot be sampled. As an example, the definition data DA1 includes a definition that specifies that during the H-detection interval (first sampling period) from the end of the H-detection shielding time until the moment it becomes low-level, the high-level power can be measured. Furthermore, the definition data DA1 includes a definition that specifies that low-level power can be measured during the L-detection interval (second sampling period) from the end of the L-detection shielding time until the moment it becomes high-level.

[0118] The control unit 162a stores the detected measurement values ​​(pfH, pfL, prH, prL) in the storage unit 162c in chronological order. This generates time-series buffer data DA2. The time-series buffer data DA2 is used for averaging the measurement values. The control unit 162a calculates the moving average time for each measurement value (pfH, pfL, prH, prL) based on the time-series buffer data DA2. Using each moving average time, the control unit 162a calculates the averaged measurement values ​​(Pf(H), Pf(L), Pr(H), Pr(L)).

[0119] The control unit 162a uses averaged measured values ​​(Pf(H), Pf(L), Pr(H), Pr(L)), a high-level set power PfH, and a low-level set power PfL to determine the applied voltage value of the attenuator 163. The control unit 162a uses the averaged measured values, the high-level set power PfH, and the low-level set power PfL to determine the applied voltage value of the attenuator 163 in a manner that makes the output of the microwave generator 16a close to the set power. For example, the control unit 162a determines a first signal (the applied voltage value for high-level power) for imparting a first attenuation amount to the microwave power, and a second signal (the applied voltage value for low-level power) for imparting a second attenuation amount to the microwave power. Then, the control unit 162a applies a voltage to the attenuator 163 via the D / A converter 167f. This performs power feedback.

[0120] The control unit 162a can also output the averaged measurement value to the controller 100. The averaged measurement value may be stored in the storage unit of the controller 100 as operating information or log information of the device, or it may be output to the outside of the device.

[0121] [Second example of a detailed structure]

[0122] Figure 10 This is a second example of a detailed structure related to the power feedback of a microwave output device. (And...) Figure 9 Compared to the structure of the first example shown, in the structure of the second example, instead of D / A converter 167f, a D / A converter 167g for high-level signals and a D / A converter 167h for low-level signals are included. Furthermore, in the structure of the second example, the synchronization signal PSS-M is not output from the pulse output unit 167d to the control unit 162a. The first and second examples differ in these aspects, but are otherwise the same. Therefore, details related to... Figure 9 Repeated explanation.

[0123] The control unit 162a is connected to a D / A converter 167g (first converter) for D / A conversion of the applied voltage value for high-level power, and a D / A converter 167h (second converter) for D / A conversion of the applied voltage value for low-level power. D / A converter 167g is preset to output an analog signal corresponding to the applied voltage value for high-level power. D / A converter 167h is preset to output an analog signal corresponding to the applied voltage value for low-level power. A solid-state relay K1 (switch) is provided between D / A converters 167g and 167h and attenuator 163, which is used to switch the connection between D / A converters 167g and 163 and between D / A converters 167h and attenuator 163. The solid-state relay K1 switches the connection directly from the pulse output unit 167d with reference to the synchronization signal PSS-M. Therefore, compared to the structure of the first example, the second example can switch the applied voltage value for high-level power and the applied voltage value for low-level power at a higher speed. That is, compared with the structure of the first example, the structure of the second example can pulse modulate the power of microwaves with a shorter period.

[0124] [Microwave power averaging]

[0125] The power waveform of a microwave with a bandwidth achieved through multi-carrier modulation is periodic. For example, with a bandwidth of 10 MHz, a carrier spacing of 10 kHz, and no pulse modulation, one cycle of microwave power is 100 μs. Typically, the detector output is an amplitude-based output; when converting this to power, errors occur between the measured microwave having a bandwidth achieved through multi-carrier modulation and other conditions. Even with bandwidth, if averaging over one cycle of 100 μs, the measured power value matches the power calculated from the detector output. Furthermore, by repeatedly averaging over periods longer than one cycle, the detector output and the measured power value become consistent, improving power accuracy. Power feedback is based on this detector output, thus ensuring the power is consistent with the measured power value. The following explanation is based on a measurement example.

[0126] Figure 11 Images (A) through (C) are examples of microwave (pulse-free modulation) waveforms with bandwidth achieved through multi-carrier operation. The horizontal axis represents frequency (MHz), and the vertical axis represents power (dBm). The bandwidth (dBm width) is set to 10MHz, and the carrier spacing is set to 10kHz. Sampling is performed every 1μs between 0μs and 100μs. The frequency amplitude is between 2455MHz and 2465MHz, and the power is between 0 and 7000W. Figure 11 (A) is the waveform of the microwave at time t = 0 μs. Figure 11(B) is the waveform of the microwave at time t = 10 μs. Figure 11 (C) is the waveform of the microwave at time t = 70 μs. For example... Figure 11 As shown in (A) to (C), it can be confirmed that the instantaneous waveform shape of a microwave with bandwidth is different every 1 μs.

[0127] Figure 12 (A) and (B) are to Figure 11 The image shows an example of a microwave waveform obtained by averaging over the BB period. The horizontal axis represents frequency (MHz), and the vertical axis represents power (W). The BB period is the power variation period of a microwave with bandwidth; in this case, one period is 100 μs. Figure 12 As shown in (A), when the amount of one cycle of the BB period is averaged, it can be confirmed that the waveform becomes flat within the 10MHz portion of the BB waveform. Figure 12 (B) is with Figure 12 The example shown in (A) is an example of a case where the resolution of the frequency axis has been improved. For example... Figure 12 As shown in (B), when the resolution of the frequency axis is increased, a waveform with a carrier spacing of 10 kHz (1001 carriers) can be identified.

[0128] Figure 13 (A) and (B) are examples of moving averages of power for microwave (pulse-free modulation) with bandwidth achieved by multi-carrier operation. The horizontal axis represents time (μs), and the vertical axis represents power (W). Figure 13 (A) is a waveform obtained by sampling multiple carriers with a period of 100μs at 1μs intervals under power feedback control. The bandwidth is 10MHz, the carrier spacing is 10kHz, and the set power is 1000W. Figure 13 As shown in (A), with power feedback control implemented, power fluctuations repetitive according to the BB cycle occur. By analyzing... Figure 13 The waveform of (A) is averaged using a moving average to obtain... Figure 13 The waveform shown in (B) is an example. A moving average is performed on 100 (100μs) 1μs samples over a 100μs period multicarrier. (See diagram for example.) Figure 13 As shown in (B), it can be confirmed that the power becomes constant over time. On the other hand, by examining the details of the power variation, it can be confirmed that there are fluctuations in the microwave (without pulse modulation) with a bandwidth of 10 MHz (standard deviation of 68 W at 1 μs sampling).

[0129] Next, the waveform under pulse modulation will be explained. When pulse modulation is performed with a bandwidth of 10MHz, a carrier spacing of 10kHz, and a period of 100μs, the waveform is extracted based on the ON and OFF times of the waveform set by the pulse frequency and duty cycle, i.e., the waveform is extracted periodically, and only a specific interval within the 100μs period is detected. This will be explained in detail below.

[0130] Figure 14 Examples (A) to (E) are examples of detector outputs for microwaves with a bandwidth achieved through multi-carrier modulation (carrier spacing 10 kHz, pulse modulation). The horizontal axis represents time (μs), and the vertical axis represents power (W). The bandwidth is set to 10 MHz, the carrier spacing to 10 kHz, and the power to 1000 W. The pulse modulation conditions are a set frequency of 10 kHz and a set duty cycle of 50%. That is, the pulse ON time is 50 μs, and the pulse OFF time is 50 μs. Figure 14 Waveform extraction is performed during the pulse ON time in (A) to (E). Figure 14 (A) is the measurement result when pulse modulation starts at t = 0 μs. Figure 14 (B) is the waveform when pulse modulation begins at t = 20 μs. Figure 14 (C) is the waveform when pulse modulation begins at t = 40 μs. Figure 14 (D) is the waveform when pulse modulation begins at t = 60 μs. Figure 14 (E) is the waveform when pulse modulation begins at t = 80 μs. For example... Figure 14 As shown in (A) to (E), it can be confirmed that the shape of the waveform changes and the detector output changes depending on the start time of the pulse modulation.

[0131] Figure 15 This table summarizes the power measurements of microwaves (carrier spacing 10 kHz, pulse modulation) with bandwidth achieved through multi-carrier modulation. Average power, standard deviation (fluctuation), maximum power, and minimum power are measured at each pulse modulation start time. The pulse modulation start times range from 0 μs to 90 μs. Figure 15 As shown, it can be confirmed that the average power, standard deviation (fluctuation), maximum power, and minimum power vary at each start time of pulse modulation. This is because the waveform extracted at the pulse ON time is insufficient to represent one cycle of the BB period.

[0132] As a countermeasure against power fluctuations dependent on the start time of pulse modulation, the set ON time and BB period of the pulse modulation are set to satisfy the following conditions. Various parameters are set to satisfy the following relationship: the set pulse ON time > BB period, that is, the pulse ON time, determined by the set pulse frequency and set duty cycle, is longer than the power fluctuation period of the bandwidth microwave. This ensures a power fluctuation of one cycle for the bandwidth microwave. The pulse ON time can be adjusted by changing the set pulse frequency and set duty cycle. The BB period can be changed by adjusting the BB width and carrier spacing. Therefore, appropriate adjustments can be made to satisfy the above conditions. Furthermore, when the plasma processing apparatus can execute multiple set pulse ON times, it is necessary to satisfy the condition that the minimum set pulse ON time is longer than the BB period. Similarly, when the plasma processing apparatus can execute multiple BB periods, it is necessary to satisfy the condition that the maximum BB period is shorter than the pulse ON time.

[0133] Figure 16 This is a table representing one example of the pulse ON time. For example... Figure 16As shown, when the set pulse frequency is 1kHz and the set duty cycle is 10%, the pulse period is 1000μs and the pulse ON time is 100μs. When the set pulse frequency is 1kHz and the set duty cycle is 90%, the pulse period is 1000μs and the pulse ON time is 900μs. When the set pulse frequency is 5kHz and the set duty cycle is 10%, the pulse period is 200μs and the pulse ON time is 20μs. When the set pulse frequency is 5kHz and the set duty cycle is 90%, the pulse period is 200μs and the pulse ON time is 180μs. When the set pulse frequency is 10kHz and the set duty cycle is 10%, the pulse period is 100μs and the pulse ON time is 10μs. When the set pulse frequency is 10kHz and the set duty cycle is 90%, the pulse period is 100μs and the pulse ON time is 90μs. When the set pulse frequency is 15kHz and the set duty cycle is 10%, the pulse period is 66.6μs and the pulse ON time is 6.66μs. When the set pulse frequency is 15kHz and the set duty cycle is 90%, the pulse period is 66.6μs and the pulse ON time is 59.94μs. When the set pulse frequency is 20kHz and the set duty cycle is 10%, the pulse period is 50μs and the pulse ON time is 5μs. When the set pulse frequency is 20kHz and the set duty cycle is 90%, the pulse period is 50μs and the pulse ON time is 45μs. When the set pulse frequency is 50kHz and the set duty cycle is 10%, the pulse period is 20μs and the pulse ON time is 2μs. When the set pulse frequency is 50kHz and the set duty cycle is 90%, the pulse period is 20μs and the pulse ON time is 18μs. In this way, the pulse ON time can be adjusted by changing the set pulse frequency and the set duty cycle.

[0134] Figure 17 This is a table representing one example of carrier spacing, BB period, and pulse ON time. For example... Figure 17As shown, in the case of single peak (SP), the number of carriers is 1. When the set BB width is 10MHz and the set carrier spacing is 10kHz, the number of carriers is 1001 and the BB period is 100μs. When the set BB width is 10.1MHz and the set carrier spacing is 10.1kHz, the number of carriers is 1001 and the BB period is 99.0099μs. In this case, the minimum pulse ON time can be set to 100μs. When the set BB width is 10.01MHz and the set carrier spacing is 100.1kHz, the number of carriers is 101 and the BB period is 9.999μs. In this case, the minimum pulse ON time can be set to 10μs. When the set BB width is 10.005MHz and the set carrier spacing is 200.1kHz, the number of carriers is 51 and the BB period is 4.9975μs. In this case, the minimum pulse ON time can be set to 5μs. When the set BB width is 1.0002MHz and the set carrier spacing is 500.1kHz, the number of carriers is 3 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. When the set BB width is 2.5005MHz and the set carrier spacing is 500.1kHz, the number of carriers is 6 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. When the set BB width is 5.001MHz and the set carrier spacing is 500.1kHz, the number of carriers is 11 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. When the set BB width is 10.002MHz and the set carrier spacing is 500.1kHz, the number of carriers is 21 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. When the set BB width is 20.004MHz and the set carrier spacing is 500.1kHz, the number of carriers is 41 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. When the set BB width is 50.01MHz and the set carrier spacing is 500.1kHz, the number of carriers is 101 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. When the set BB width is 99.5199MHz and the set carrier spacing is 500.1kHz, the number of carriers is 200 and the BB period is 1.9996μs. In this case, the minimum pulse ON time can be set to 2μs. In this way, the BB period can be changed by adjusting the BB width and carrier spacing.That is, it is possible to adjust at least one of the following: the set pulse frequency, the set duty cycle, the BB width, and the carrier spacing, to change the setting pulse ON time to satisfy the relationship that the BB period is greater than the set pulse ON time.

[0135] Figure 18 Images (A) through (E) are examples of detector outputs for microwaves with a bandwidth achieved through multi-carrier modulation (carrier spacing of 500.1 kHz, pulse modulation). The horizontal axis represents time (μs), and the vertical axis represents power (W). The bandwidth is set to 10.002 MHz, the carrier spacing to 500.1 kHz, and the power to 1000 W. That is, the BB period is 1.9996 μs. The pulse modulation conditions are a pulse frequency of 10 kHz and a duty cycle of 50%. That is, the pulse ON time is 50 μs, and the pulse OFF time is 50 μs. The pulse ON time is approximately 25 times the BB period. Figure 18 Waveform extraction is performed during the pulse ON time in (A) to (E). Figure 18 (A) is the measurement result when pulse modulation starts at t = 0 μs. Figure 18 (B) is the waveform when pulse modulation begins at t = 20 μs. Figure 18 (C) is the waveform when pulse modulation begins at t = 40 μs. Figure 18 (D) is the waveform when pulse modulation begins at t = 60 μs. Figure 18 (E) is the waveform when pulse modulation begins at t = 80 μs. For example... Figure 18 As shown in (A) to (E), it can be confirmed that the waveform shape is uniform regardless of the start time of pulse modulation, and the detection output is stable.

[0136] Figure 19 This table summarizes the power measurements of microwaves with a bandwidth achieved through multi-carrier modulation (carrier spacing 500.1 kHz, pulse modulation). The average power, standard deviation (fluctuation), maximum power, and minimum power are measured at each start time of pulse modulation. The start times of pulse modulation range from 0 μs to 90 μs. Figure 19 As shown, it can be confirmed that regardless of the start time of pulse modulation, the average power, standard deviation (fluctuation), maximum power, and minimum power are constant. This is because the waveform extracted at the pulse ON time satisfies more than one cycle of the BB period. By comparison... Figure 15 and Figure 19 It can be confirmed that by ensuring the pulse ON time is longer than the power fluctuation period of a bandwidth microwave, stable microwave input for each pulse can be achieved. That is, it can be confirmed that the power input for each pulse can be stabilized while ensuring the robustness of the plasma generated by bandwidth microwaves.

[0137] [Improvements in microwave power averaging]

[0138] Figure 20 This is a diagram illustrating another example of a structure related to microwave power feedback. Figure 20 The structure shown is Figure 7 The difference between the structures shown is that the pulse generator 162b and the waveform generator 161 are communicatively connected via a cable or the like; otherwise, they are the same. The following explanation focuses on these differences, omitting repetitive details.

[0139] The synchronization signal PSS-M generated by pulse generator 162b is sent to waveform generator 161. Waveform generator 161 generates microwave waveforms according to the timing based on the synchronization signal PSS-M. This allows the microwave output with bandwidth to be synchronized with the pulse signal. As described above, if the relationship that the pulse ON time is longer than the BB period can be satisfied, stable microwave input for each pulse can be achieved. However, the closer the BB period is to the pulse ON time, the more likely the average power and fluctuations will become unstable. Figure 21 Figures (A) to (C) illustrate the timing of the pulse ON signal and the BB cycle. The horizontal axis represents time (μs), and the vertical axis represents power (W). The timing diagram below the curve shows the timing of the pulse ON time (high level) and the pulse OFF time (low level). Figure 21 The waveform shown in (A) is the case where the pulse ON time starts at the beginning of the BB cycle. Figure 21 The waveform shown in (B) is the case where the pulse ON time is shifted by 0.5μs from the beginning of the BB period. Figure 21 The waveform shown in (C) is the case where the pulse ON time is offset by 1.0 μs from the beginning of the BB period. Figure 21 As shown in (A) to (C), the waveform shape changes during the excess portion of the pulse ON time (dashed lines in the figure). Therefore, by synchronizing the bandwidth-bound microwave output with the pulse signal, the waveform of each pulse can be kept constant, thus making the average power and fluctuations more stable.

[0140] The above describes various implementation methods, but is not limited to the above implementation methods, and various variations are possible.

[0141] In the above embodiments, an example of microwave generator 16a being separated from waveform generator 161 has been described, but they can also be configured as a single device.

[0142] In the above embodiments, an example of generating a microwave power synchronization signal based on a high-frequency power synchronization signal was described, but it is also possible to generate a high-frequency power synchronization signal based on a microwave power synchronization signal.

[0143] When the plasma processing device 1 uses only the Pf mode, the measurement unit 16k may not include a structure for measuring reflected waves.

[0144] The above embodiments illustrate an example using an ON / OFF controlled pulse, but this can also be applied to cases using a High / Low controlled pulse. In this case, the ON (high level) pulse duration may be longer than the power variation period of a microwave with bandwidth, and the OFF (low level) pulse duration may be longer than the power variation period of a microwave with bandwidth.

[0145] Based on the above description, it can be understood that various modifications can be made to the various embodiments of this disclosure without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and their true scope and spirit are given by the technical solutions of the invention.

[0146] The aforementioned microwave power control can also be applied to the power control of pulse-modulated RF signals (RF power). For example, Figure 1 The plasma processing apparatus shown can be modified into a capacitively coupled plasma (CCP) or inductively coupled plasma (ICP) plasma processing apparatus. Figure 1 The microwave output device 16 for plasma formation shown (an example of a power supply unit) can be converted into a high-frequency power supply (an example of a power supply unit) that applies a high-frequency power source with an RF signal. The high-frequency power supply is coupled to the chamber body 12 via at least one impedance matching circuit. In one embodiment, the RF signal has a frequency in the range of 13MHz to 150MHz. This allows plasma to be formed from the process gas supplied to the processing space S. The RF signal from this high-frequency power supply and / or the high-frequency power supply 58 can be pulsed. The pulsed RF signal is set in the same way as the microwave described above, such that the pulse ON time, determined by the set pulse frequency and set duty cycle, is longer than the power variation period of the high-frequency power with bandwidth. This allows for the input of high-frequency power with stable pulses.

[0147] Explanation of reference numerals in the attached figures

[0148] 1…Plasma processing apparatus, 12…Cavity body, 14…Platform, 16…Microwave output device, 16a…Microwave generator, 16f…First directional coupler, 16h…Second directional coupler, 16k…Measuring section (an example of a measuring section), 16t…Output section, 18…Antenna, 20…Dielectric window, 26…Tuner, 27…Mode converter, 28…Coaxial waveguide, 30…Slit plate, 32…Dielectric plate, 34…Cooling jacket, 38…Gas supply system, 58…High-frequency power supply, 60…Matching unit, 100…Controller, 161…Waveform generator, 162…Power control section, 163…Attenuator, 164…Amplifier, 165…Amplifier, 166…Mode converter.

Claims

1. A plasma processing apparatus, comprising: The main body of the chamber; and A power supply unit for stimulating the gas supplied to the main body of the chamber. The power supply unit is used to supply power, which has a center frequency, bandwidth, and carrier spacing corresponding to a set frequency, a set bandwidth, and a set carrier spacing indicated by the controller, respectively. The power of the power is pulse-modulated such that its pulse frequency, duty cycle, high-level power, and low-level power correspond to the set pulse frequency, set duty cycle, high-level set power, and low-level set power indicated by the controller, respectively. Furthermore, the pulse on-time determined by the set pulse frequency and the set duty cycle is longer than the power variation period of the power with bandwidth.

2. The plasma processing apparatus as described in claim 1, wherein, The power supply department includes: A microwave generator that produces pulse-modulated microwaves as the power source; An output unit that outputs microwaves propagating from the microwave generator; A first directional coupler, the output of which is a portion of a traveling wave propagating from the microwave generator to the output; and The measurement unit, based on a portion of the traveling wave output from the first directional coupler, determines a first high measurement value and a first low measurement value, respectively representing a high level and a low level of the power of the traveling wave in the output unit. In the microwave generator, The first highest and first lowest measurements were averaged according to the specified moving average time and the specified sampling interval. Based on the averaged first high measured value and the set high level power, the high level power of the pulse-modulated microwave is controlled. Based on the averaged first low measurement value and the low-level set power, the low-level power of the pulse-modulated microwave is controlled.

3. The plasma processing apparatus as described in claim 2, wherein, The power supply unit also includes a second directional coupler that outputs a portion of the reflected wave returning to the output unit. The measurement unit further determines, based on a portion of the reflected wave output from the second directional coupler, a second high measurement value and a second low measurement value, respectively representing high and low levels of power of the reflected wave in the output unit. In the microwave generator, The second highest measurement and the second lowest measurement were averaged according to the specified moving average time and the specified sampling interval. Based on the averaged first high measured value, the averaged second high measured value, and the set high-level power, the high-level power of the pulse-modulated microwave is controlled. Based on the averaged first low measurement value, the averaged second low measurement value, and the low-level set power, the low-level power of the pulse-modulated microwave is controlled.

4. The plasma processing apparatus as described in claim 2 or 3, wherein, The low-level pulse time, determined by the set pulse frequency and the set duty cycle, is longer than the power variation period of a microwave with bandwidth.

5. The plasma processing apparatus according to any one of claims 1 to 3, wherein, The low level is 0.

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