Plasma processing equipment

Abstract

To easily adjust an output wave by the frequency of a microwave used for plasma generation.SOLUTION: In one exemplary embodiment, a plasma processing device is provided. A microwave output device of the plasma processing device is configured to output a microwave to be provided within a chamber, and a control device controls operation of the microwave output device. The microwave output by the microwave output device includes an output wave for transmitting power used for plasma generation and a group of broadband swept waves used for detecting a plasma state. In the microwave output device, a modulation unit modulates the microwave and transmits it to a waveguide, and a demodulation unit receives and demodulates a group of reflected waves in which the group of swept waves is reflected by plasma within the chamber. The control device determines a frequency of the output wave based on the group of reflected waves, and controls the microwave output device to output the output wave of this frequency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An exemplary embodiment of the present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] Plasma processing apparatuses are used in the manufacture of electronic devices such as semiconductor devices. There are several types of plasma processing apparatuses, including capacitively coupled types, but plasma processing apparatuses that generate plasma by exciting gas using microwaves are also used. Patent Document 1 discloses a plasma processing apparatus that uses microwaves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-194943 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for easily adjusting the output wave by adjusting the frequency of the microwave used to generate 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 microwave output device, and a control device. The microwave output device is configured to output microwaves that are provided into the chamber via a waveguide and an antenna. The control device is configured to control the operation of the microwave output device. The microwaves output by the microwave output device include an output wave that carries power used to generate plasma and a wideband sweep wave group that is used to detect the plasma state in the chamber. The microwave output device has a modulator and a demodulator. The modulator is configured to modulate the microwave and transmit it to the waveguide. The demodulator is configured to receive and demodulate a reflected wave group that is reflected by the plasma in the chamber and that is included in the microwaves transmitted to the waveguide by the modulator and provided into the chamber via the antenna. The control device can be configured to determine the frequency of the output wave based on the reflected wave group and control the microwave output device to output an output wave of this frequency. [Effects of the Invention]

[0006] According to one exemplary embodiment, the power wave can be easily adjusted by the frequency of the microwaves used to generate the plasma. [Brief explanation of the drawings]

[0007] [Figure 1] 1 illustrates a plasma processing apparatus according to an exemplary embodiment; [Figure 2] FIG. 2 illustrates an example modulation section. [Figure 3] FIG. 2 illustrates an example demodulation unit. [Figure 4] 2 is a diagram for explaining the operation of the plasma processing apparatus illustrated in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various exemplary embodiments are described below.

[0009] The output wave used to generate the plasma may be a microwave. In this case, the frequency of the output wave absorbed by the generated plasma may vary depending on the state of the plasma. The frequency of the output wave can be adjusted to accommodate such variations using a matching box. However, frequency adjustment using a matching box may not be able to timely follow the variations in the plasma state due to delays caused by the mechanical operation of the matching box.

[0010] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a microwave output device, and a control device. The microwave output device is configured to output microwaves that are provided into the chamber via a waveguide and an antenna. The control device is configured to control the operation of the microwave output device. The microwaves output by the microwave output device include an output wave that carries power used to generate plasma and a wideband sweep wave group that is used to detect the plasma state in the chamber. The microwave output device has a modulator and a demodulator. The modulator is configured to modulate the microwave and transmit it to the waveguide. The demodulator is configured to receive and demodulate a reflected wave group that is reflected by the plasma in the chamber and that is included in the microwaves transmitted to the waveguide by the modulator and provided into the chamber via the antenna. The control device can be configured to determine the frequency of the output wave based on the reflected wave group and control the microwave output device to output an output wave of this frequency.

[0011] The reflected waves generated when the broadband sweep waves are reflected by the plasma represent the microwave frequencies absorbed by the plasma. Therefore, by using the reflected waves, it is possible to easily generate output waves with frequencies effective for plasma excitation in a timely manner in response to fluctuations in the plasma state.

[0012] In one exemplary embodiment, the control device can be configured to obtain a first frequency of a sweep wave having the lowest reflectivity among the sweep waves based on the group of reflected waves, and control the microwave output device to output an output wave of the first frequency.

[0013] In one exemplary embodiment, the control device may determine that the first frequency acquired at the first timing is not within a preset bandwidth that includes the first frequency acquired at a second timing before the first timing. In this case, the control device may be configured to control the microwave output device to output an output wave of the first frequency acquired at the first timing.

[0014] In one exemplary embodiment, the control device may determine that the first frequency obtained at the first timing is not within the preset band, in which case the control device may be configured to control the microwave output device to output an output wave of the first frequency obtained at the first timing.

[0015] In one exemplary embodiment, the control device can be configured to control the microwave output device to output a plurality of output waves having a plurality of first frequencies obtained at a plurality of timings, respectively.

[0016] In one exemplary embodiment, the control device can be configured to acquire a frequency spectrum of the reflected waves and control the microwave output device to determine a frequency of an output wave such that a difference between the frequency spectrum and a previously acquired reference frequency spectrum is reduced.

[0017] In one exemplary embodiment, the power of the output wave may be 5000 W or less, and the frequency of the output wave may be 2400 to 2500 MHz.

[0018] In one exemplary embodiment, the power of the sweep waves included in the sweep wave group may be less than the power of the output wave, 50 W or less.

[0019] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0020] 1 is a diagram showing a plasma processing apparatus according to one embodiment. As shown in FIG. 1, the plasma processing apparatus 1 includes a chamber 12 and a microwave output device MW. The plasma processing apparatus 1 may further include a stage 14, an antenna 18, and a dielectric window 20.

[0021] The chamber 12 provides a processing space S therein. The chamber 12 has a sidewall 12a and a bottom 12b. The sidewall 12a is formed in a generally cylindrical shape. The central axis of the sidewall 12a generally coincides with an axis Z extending in the vertical direction. The bottom 12b is provided on the lower end side of the sidewall 12a. An exhaust hole 12h for exhausting air is provided in the bottom 12b. The upper end of the sidewall 12a is open.

[0022] A dielectric window 20 is provided on the upper end of the side wall 12a. The dielectric window 20 has a lower surface 20a facing 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 interposed between the dielectric window 20 and the upper end of the side wall 12a. The O-ring 19 more reliably seals the chamber 12.

[0023] The stage 14 is housed within the processing space S. The stage 14 is arranged so as to face the dielectric window 20 in the vertical direction. The stage 14 is arranged so as to sandwich the processing space S between the dielectric window 20 and the stage 14. The stage 14 is configured to support a wafer WP placed thereon.

[0024] In one embodiment, the stage 14 includes a base 14a and an electrostatic chuck 14c. The base 14a has a substantially disk shape and is made of a conductive material such as aluminum. The central axis of the base 14a substantially coincides with the 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 12 along the outer periphery of the cylindrical support 48. An annular exhaust path 51 is formed between the cylindrical support 50 and the side wall 12a.

[0025] A baffle plate 52 is provided above the exhaust path 51. The baffle plate 52 has a ring shape. A plurality of through holes are formed in the baffle plate 52, penetrating the baffle plate 52 in the thickness direction. The above-mentioned exhaust holes 12h are provided below the baffle plate 52. An exhaust device 56 is connected to the exhaust holes 12h via an exhaust pipe 54. The exhaust device 56 has an automatic pressure control valve (APC) and a vacuum pump such as a turbomolecular pump. The exhaust device 56 can reduce the pressure in the processing space S to a desired vacuum level.

[0026] The base 14a also serves as a radio-frequency electrode. A radio-frequency power supply 58 for radio-frequency bias is electrically connected to the base 14a via a power feed rod 62 and a matching unit 60. The radio-frequency power supply 58 outputs a constant frequency, for example, a 13.56 MHz radio-frequency wave, at a set power level, suitable for controlling the energy of ions attracted to the wafer WP.

[0027] Furthermore, the high-frequency power supply 58 may have a pulse generator and pulse-modulate the high-frequency power (RF power) before applying it to the base 14a. In this case, the high-frequency power supply 58 pulse-modulates the RF power so that the RF power periodically alternates between high-level power and low-level power. The high-frequency power supply 58 adjusts the pulse based on a synchronization signal PSS-R generated by the pulse generator. The synchronization signal PSS-R is a signal that determines the period and duty ratio of the high-frequency power. As an example of settings for pulse modulation, the pulse frequency is 10 Hz to 50 kHz, and the pulse duty ratio (ratio of high-level power time to pulse period) is 10% to 90%.

[0028] The matching unit 60 contains a matcher for matching the impedance on the high-frequency power supply 58 side with the impedance on the load side, mainly consisting of the electrodes, plasma, and chamber 12. This matcher includes a blocking capacitor for generating a self-bias. When the high-frequency power is pulse-modulated, the matching unit 60 operates to match based on the synchronization signal PSS-R.

[0029] An electrostatic chuck 14c is provided on the upper surface of the base 14a. The electrostatic chuck 14c holds the wafer 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 substantially coincides with axis Z. The electrode 14d of the electrostatic chuck 14c is made of a conductive film and is provided between the insulating films 14e and 14f. A DC power supply 64 is electrically connected to the electrode 14d via a switch 66 and a coated wire 68. The electrostatic chuck 14c can attract and hold the wafer WP by Coulomb force generated by a DC voltage applied from the DC power supply 64. A focus ring 14b is provided on the base 14a. The focus ring 14b is arranged to surround the wafer WP and the electrostatic chuck 14c.

[0030] A coolant chamber 14g is provided inside the base 14a. The coolant chamber 14g is formed, for example, to extend about the axis Z. A coolant is supplied to the coolant chamber 14g from a chiller unit via a pipe 70. The coolant supplied to the coolant chamber 14g is returned to the chiller unit via a pipe 72. The temperature of the coolant is controlled by the chiller unit, thereby controlling the temperature of the electrostatic chuck 14c and, ultimately, the temperature of the wafer WP.

[0031] A gas supply line 74 is formed in the stage 14. The gas supply line 74 is provided to supply a heat transfer gas, for example, He gas, between the upper surface of the electrostatic chuck 14c and the back surface of the wafer WP.

[0032] Returning to FIG. 1 , the plasma processing apparatus 1 further includes a waveguide 21, a tuner 26, and a coaxial waveguide 28. The microwave output device MW is connected to one end of the waveguide 21 (the microwave output device MW will be described in detail later). The other end of the waveguide 21 is connected to the coaxial waveguide 28. The waveguide 21 is, for example, a rectangular waveguide. The waveguide 21 is provided with a tuner 26. The tuner 26 has stubs 26a, 26b, and 26c. Each of the stubs 26a, 26b, and 26c is configured so that the amount of protrusion thereof into the internal space of the waveguide 21 can be adjusted. The tuner 26 adjusts the protruding positions of the stubs 26a, 26b, and 26c relative to a reference position, thereby matching the impedance of the microwave output device MW with the impedance of a load, for example, the chamber 12.

[0033] The coaxial waveguide 28 includes an outer conductor 28a and an inner conductor 28b. The outer conductor 28a has a generally cylindrical shape, and its central axis substantially coincides with the 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 substantially coincides with the axis Z. The coaxial waveguide 28 transmits the microwaves output from the microwave output device MW via the waveguide 21 to the antenna 18.

[0034] The antenna 18 is provided on a surface 20b opposite to the lower surface 20a of the dielectric window 20. The antenna 18 includes a slot plate 30, a dielectric plate 32, and a cooling jacket .

[0035] The slot plate 30 is provided on the surface 20b of the dielectric window 20. The slot plate 30 is made of a conductive metal and has a substantially disk shape. The central axis of the slot plate 30 substantially coincides with the axis Z. A plurality of slot holes 30a are formed in the slot plate 30. In one example, the plurality of slot holes 30a constitute a plurality of slot pairs. Each of the plurality of slot pairs includes two slot holes 30a that are substantially elongated and extend in directions that intersect each other. The plurality of slot pairs are arranged along one or more concentric circles around the axis Z. A through hole 30d is formed in the center of the slot plate 30, through which a conduit 36, described later, can pass.

[0036] The dielectric plate 32 is provided on the slot plate 30. The dielectric plate 32 is made of a dielectric material such as quartz and has a substantially disk shape. The central axis of the dielectric plate 32 substantially coincides with the axis Z. The cooling jacket 34 is provided on the dielectric plate 32. The dielectric plate 32 is provided between the cooling jacket 34 and the slot plate 30.

[0037] The surface of the cooling jacket 34 is electrically conductive. A flow path 34a is formed inside the cooling jacket 34. A refrigerant is supplied to the flow path 34a. The lower end of the outer conductor 28a is electrically connected to the upper surface of the cooling jacket 34. The lower end of the inner conductor 28b is electrically connected to the slot plate 30 through a hole formed in the center of the cooling jacket 34 and the dielectric plate 32.

[0038] The microwaves from the coaxial waveguide 28 propagate through the dielectric plate 32 and are supplied to the dielectric window 20 through the multiple slot holes 30a of the slot plate 30. The microwaves supplied to the dielectric window 20 are introduced into the processing space S.

[0039] A conduit 36 ​​passes through the inner hole of the inner conductor 28b of the coaxial waveguide 28. As described above, a through-hole 30d through which the conduit 36 ​​can pass is formed in the center of the slot plate 30. The conduit 36 ​​extends through the inner hole of the inner conductor 28b and is connected to a gas supply system 38.

[0040] The gas supply system 38 supplies a process gas for processing the wafer WP to the conduit 36. The gas supply system 38 may include a gas source 38a, a valve 38b, and a flow rate controller 38c. The gas source 38a is a source of the process gas. The valve 38b switches the supply of the process gas from the gas source 38a on and off. The flow rate controller 38c is, for example, a mass flow controller, and adjusts the flow rate of the process gas from the gas source 38a.

[0041] The plasma processing apparatus 1 may further include an injector 41. The injector 41 supplies gas from the conduit 36 ​​to 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 gas is excited by microwaves introduced into the processing space S from the dielectric window 20. This generates plasma in the processing space S, and the wafer WP is processed by active species such as ions and / or radicals from the plasma.

[0042] The plasma processing apparatus 1 further includes a control device 100. The control device 100 controls all parts of the plasma processing apparatus 1. In particular, the control device 100 is configured to control the operation of the microwave output device MW. The control device 100 may include a processor such as a CPU, a user interface, and a storage unit.

[0043] The processor executes the programs and process recipes stored in the storage unit to comprehensively control each part such as the microwave output device MW, the stage 14, the gas supply system 38, and the exhaust device 56.

[0044] The user interface includes a keyboard or touch panel through which the process manager inputs commands to manage the plasma processing apparatus 1, a display that visualizes the operating status of the plasma processing apparatus 1, and the like.

[0045] The storage unit stores control programs (software) for implementing various processes executed in the plasma processing apparatus 1 under the control of the processor, as well as process recipes including processing condition data, etc. The processor calls up and executes the various control programs from the storage unit as needed, such as in response to instructions from a user interface. Under the control of such a processor, the desired process is executed in the plasma processing apparatus 1.

[0046] The microwave output device MW outputs microwaves (output waves) for exciting the process gas supplied into the chamber 12. The microwave output device MW is configured to output microwaves that are provided into the chamber 12 via the waveguide 21 and the antenna 18. The microwave output device MW is configured to variably adjust the frequency, power, and bandwidth of the microwaves.

[0047] The microwave output device MW can output a microwave of a single frequency (for example, an output wave used for plasma generation) by, for example, setting the microwave bandwidth to approximately 0. The microwave output device MW can output a microwave having a bandwidth containing multiple frequency components therein (for example, a group of sweep waves used for detecting the plasma state).

[0048] The power of these multiple frequency components may be the same, or only the center frequency component within the band may have a power greater than the power of the other frequency components. In one example, the microwave output unit MW can adjust the microwave power within a range of 0 W to 5000 W.

[0049] The microwave output device MW can adjust the frequency or center frequency of the microwave within the range of 2400 MHz to 2500 MHz. The microwave output device MW can adjust the microwave bandwidth within the range of 0 MHz to 100 MHz. The microwave output device MW can adjust the frequency pitch (carrier pitch) of multiple frequency components of the microwave within the bandwidth within the range of 0 to 25 kHz.

[0050] Furthermore, the power of the sweep waves included in the sweep wave group can be less than the power of the output wave, 50 W or less.

[0051] Next, the microwave output device MW will be described in detail. The microwave output device MW has a signal wave control unit 15, a modulation unit 16, and a demodulation unit 17. The modulation unit 16 is configured to modulate microwaves and output them as traveling waves Pf to a waveguide 21. The microwaves (traveling waves Pf) output by the modulation unit 16 include an output wave that transmits power used to generate plasma and a wideband sweep wave group used to detect the plasma state in the chamber 12. The demodulation unit 17 is configured to receive and demodulate a reflected wave group (reflected waves Pr) that is formed when the sweep wave group is reflected by the plasma in the chamber 12 via the waveguide 21. The signal wave control unit 15 is configured to control the generation of microwaves by the modulation unit 16 based on the traveling wave Pf and the reflected wave Pr (by feeding back the traveling wave Pf and the reflected wave Pr).

[0052] The modulation unit 16 will be described with reference to Fig. 2. The modulation unit 16 includes a baseband signal generation unit 161, D / A converters 162a and 162b, low-pass filters 163a and 163b, an IQ modulator 164, a PLL oscillator 165, and a phase adjuster 166. The modulation unit 16 further includes an amplifier 167, a band-pass filter 168, and a directional coupler 169. The baseband signal generation unit 161 includes a sweep wave group output unit 161a, an output wave output unit 161b, and an inverse Fourier transform unit 161c.

[0053] The microwave output device MW includes a signal wave control unit 15. The sweep wave group output unit 161a uses digital data related to the sweep wave group provided by the signal wave control unit 15 of the microwave output device MW to send a signal group SGa related to the sweep wave group to an inverse Fourier transform unit 161c. The output wave output unit 161b uses digital data related to the output wave provided by the signal wave control unit 15 to send a signal group SGb related to the output wave to the inverse Fourier transform unit 161c. The inverse Fourier transform unit 161c combines the signal groups SGa and SGb, performs an inverse Fourier transform on the resulting signal wave, and sends the resultant signal wave to a D / A converter 162b for conversion into an analog signal. The inverse Fourier transform unit 161c combines the signal groups SGa and SGb, performs an inverse Fourier transform on the resulting signal wave, and sends the resultant signal wave to a D / A converter 162a for conversion into an analog signal.

[0054] IQ modulator 164 modulates the analog signals (I signal and Q signal) sent from D / A converter 162a and D / A converter 162b using a signal from PLL oscillator 165 and a signal whose phase is shifted by 90 degrees by phase adjuster 166. The signal (traveling wave Pf) modulated by IQ modulator 164 is sent to amplifier 167 where it is amplified, and after high-frequency and low-frequency components are removed by band-pass filter 168, it is sent to waveguide 21 via directional coupler 169. The traveling wave Pf sent to waveguide 21 includes an output wave and a group of sweep waves.

[0055] The demodulation unit 17 will be described with reference to Fig. 3. The demodulation unit 17 includes a band-pass filter 171a, a band-pass filter 171b, a PLL oscillator 172, a phase adjuster 173, an IQ demodulator 174a, and an IQ demodulator 174b. The demodulation unit 17 further includes a low-pass filter 175a1, a low-pass filter 175a2, a low-pass filter 175b1, and a low-pass filter 175b2. The demodulation unit 17 includes an A / D converter 176a1, an A / D converter 176a2, an A / D converter 176b1, an A / D converter 176b2, and a signal processing unit 177. The signal processing unit 177 includes a Fourier transform unit 177b and a Fourier transform unit 177a.

[0056] The bandpass filter 171a removes high-frequency and low-frequency components from the reflected wave Pr transmitted from the directional coupler 169 of the modulation unit 16. The bandpass filter 171b removes high-frequency and low-frequency components from the traveling wave Pf transmitted from the directional coupler 169.

[0057] IQ demodulator 174a demodulates the reflected wave Pr of the analog signal transmitted through bandpass filter 171a into a Q signal and an I signal using a signal from PLL oscillator 172 and a signal whose phase is shifted by 90 degrees by phase adjuster 173. The Q signal and I signal demodulated by IQ demodulator 174a are transmitted to lowpass filters 175a1 and 175a2, respectively, where high-frequency components are removed. The Q signal transmitted through lowpass filter 175a1 is converted into a digital signal by A / D converter 176a1. The I signal transmitted through lowpass filter 175a2 is converted into a digital signal by A / D converter 176a2.

[0058] IQ demodulator 174b demodulates the traveling wave Pf of the analog signal transmitted through bandpass filter 171b into a Q signal and an I signal using a signal from PLL oscillator 172 and a signal whose phase is shifted by 90 degrees by phase adjuster 173. The Q signal and I signal demodulated by IQ demodulator 174b are transmitted to lowpass filters 175b1 and 175b2, respectively, where high-frequency components are removed. The Q signal transmitted through lowpass filter 175b1 is converted into a digital signal by A / D converter 176b1. The I signal transmitted through lowpass filter 175b2 is converted into a digital signal by A / D converter 176b2.

[0059] The Fourier transform unit 177a performs a Fourier transform on the Q signal from the A / D converter 176a1 and the I signal from the A / D converter 176a2, and transmits the reflected wave spectrum data Pr-SD to the signal wave control unit 15. The Fourier transform unit 177b performs a Fourier transform on the Q signal from the A / D converter 176b1 and the I signal from the A / D converter 176b2, and transmits the traveling wave spectrum data Pf-SD to the signal wave control unit 15.

[0060] Thus, the microwave output device MW according to one embodiment outputs, in addition to the output wave used for plasma generation, a wideband sweep wave group used for detecting the plasma state, in other words, the plasma impedance, for each frequency. The sweep wave group includes multiple sweep waves with different frequencies. The power (intensity) of the sweep waves included in the sweep wave group is smaller than the power (intensity) of the output wave, and can be, for example, 50 W or less. The microwave output device MW outputs the sweep wave group continuously (for example, always) while the plasma processing apparatus 1 is in operation. Each of the multiple sweep waves included in the sweep wave group has the frequency of each of the multiple reflected waves included in the reflected wave group.

[0061] Among the reflected waves received by the microwave output device MW, the frequency of the reflected wave absorbed by the plasma is the frequency with the lowest power in a frequency spectrum showing the power (intensity) of the reflected wave group relative to the frequency of the reflected wave group. FIG. 4 shows an example of such a frequency spectrum. The vertical axis represents the power (intensity) of the reflected wave group (MW Pr), and the horizontal axis represents the frequency included in the reflected wave group. The frequency with the lowest value along the vertical axis is the frequency absorbed by the plasma. Curves G1, G2, and G3 show the frequency spectra of the reflected wave groups obtained from plasma in different states. In the plasma state corresponding to curve G1, microwaves of frequency FQ1 are absorbed by the plasma in that state (the impedance of the plasma in that state is lowest for microwaves of frequency FQ1; the same applies below). In the plasma state corresponding to curve G2, microwaves of frequency FQ2 are absorbed by the plasma in that state. In the plasma state corresponding to curve G3, microwaves of frequency FQ3 are absorbed by the plasma in that state.

[0062] The operation of the microwave output device MW described below can be realized by the control of the control device 100. Note that the operation of the microwave output device MW may also be realized by the signal wave control unit 15 of the microwave output device MW shown in FIG.

[0063] The control device 100 can determine the frequency of the output wave based on the group of reflected waves received by the microwave output device MW, and control the microwave output device MW to output the output wave of this determined frequency. In this case, specific examples of the control of the microwave output device MW executed by the control device 100 can be, for example, controls PR1 to PR5 described below.

[0064] (Control PR1) The control device 100 can obtain a first frequency of a sweep wave having the lowest reflectivity among the sweep waves based on the reflected waves (e.g., the frequency of a reflected wave having the lowest power (intensity) among the reflected waves), and control the microwave output device MW to output an output wave of the first frequency. For example, in the plasma states corresponding to the curves G1, G2, and G3 in FIG. 4, the frequencies FQ1, FQ2, and FQ3 correspond to the first frequencies, respectively. The reflectivity can be, for example, the ratio (%) of the power (intensity) of the reflected wave to the power (intensity) of the sweep wave for each frequency.

[0065] (Control PR2) The control device 100 may determine that the first frequency acquired at the first timing is not within a preset bandwidth that includes the first frequency acquired at the second timing before the first timing. In other words, the control device 100 may determine that the first frequency acquired at the first timing and the first frequency acquired at the second timing are different. In this case, the control device 100 may control the microwave output device MW to output an output wave of the first frequency acquired at the first timing. For example, consider a case where the plasma state at the first timing is the plasma state according to curve G3 and the plasma state at the second timing before the first timing is the plasma state according to curve G1. In this case, the control device 100 may determine that the frequency FQ3, which is the first frequency acquired at the first timing, is different from the frequency FQ1, which is the first frequency acquired at the second timing. Then, the control device 100 may control the microwave output device MW to output an output wave of frequency FQ3 acquired at the first timing.

[0066] (Control PR3) The control device 100 may determine that the first frequency acquired at the first timing is not within a preset band. In this case, the control device 100 may control the microwave output device MW to output an output wave of the first frequency acquired at the first timing. For example, consider a case where the plasma state at the first timing is a plasma state according to curve G3. In this case, the control device 100 determines that the frequency FQ3, which is the first frequency acquired at the first timing, is not within a preset band (for example, a band that includes frequency FQ1 but does not include frequency FQ3). As a result, the control device 100 may control the microwave output device MW to output an output wave of frequency FQ3 acquired at the first timing.

[0067] (Control PR4) The control device 100 can control the microwave output device MW to output a plurality of output waves having a plurality of first frequencies obtained at a plurality of timings. For example, consider a case where the plasma state at a first timing is the plasma state according to curve G3, and the plasma state at a second timing is the plasma state according to curve G1. Assume that the second timing occurs before the first timing. In this case, the control device 100 can control the microwave output device MW to simultaneously (or sequentially) output an output wave having a frequency FQ1 obtained at the first timing and a frequency FQ2 obtained at the second timing. The first timing and the second timing are the two most recent timings, and the number of such new timings is not limited to two and can be two or more (plural).

[0068] (Control PR5) The control device 100 acquires the frequency spectrum of the reflected wave group and can control the microwave output device MW to determine the frequency of the output wave so as to reduce the difference between the acquired frequency spectrum and a previously acquired reference frequency spectrum. For example, consider a case where the control device 100 acquires the frequency spectrum of the reflected wave group corresponding to curve G1 and has previously acquired a reference frequency spectrum corresponding to curve G3. In this case, the control device 100 can control the microwave output device MW to determine the frequency of the output wave so as to reduce the difference between the frequency spectrum corresponding to curve G1 and the reference frequency spectrum corresponding to curve G3. Reducing the difference between these two spectra can, for example, mean that the difference between the spectra for each frequency is within a preset range.

[0069] In the plasma processing apparatus 1, the reflected waves generated when the broadband sweep waves are reflected by the plasma indicate the frequency of the microwaves absorbed by the plasma. The plasma processing apparatus 1 determines the frequency of the output waves using the reflected waves, and therefore can easily generate output waves with a frequency effective for plasma excitation in a timely manner in response to fluctuations in the plasma state.

[0070] 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. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0071] 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]

[0072] 1...plasma processing apparatus, 100...controller, 12...chamber, 16...modulator, 17...demodulator, 18...antenna, 21...waveguide, MW...microwave output device.

Claims

1. a chamber; a microwave output device configured to output microwaves that are provided into the chamber via a waveguide and an antenna; a control device configured to control the operation of the microwave output device; Equipped with the microwaves output by the microwave output device include an output wave for transmitting power used for plasma generation and a broadband sweep wave group used for detecting a plasma state in the chamber; the microwave output device includes a modulation unit configured to modulate the microwaves and transmit them to the waveguide, and a demodulation unit configured to receive, via the waveguide, a reflected wave group formed by reflecting the sweep wave group, which is included in the microwaves transmitted to the waveguide by the modulation unit and provided into the chamber via the antenna, by plasma in the chamber, and to demodulate the reflected wave group; The control device obtaining a first frequency of a sweep wave having the lowest reflectivity among the sweep waves based on the reflected wave group, and controlling the microwave output device to output the output wave of the first frequency; and when it is determined that the first frequency acquired at a first timing is not within a preset bandwidth including the first frequency acquired at a second timing before the first timing, the microwave output device is controlled to output the output wave of the first frequency acquired at the first timing. Plasma processing equipment.

2. A chamber; a microwave output device configured to output microwaves that are provided into the chamber via a waveguide and an antenna; a control device configured to control the operation of the microwave output device; Equipped with the microwaves output by the microwave output device include an output wave for transmitting power used for plasma generation and a broadband sweep wave group used for detecting a plasma state in the chamber; the microwave output device includes a modulation unit configured to modulate the microwaves and transmit them to the waveguide, and a demodulation unit configured to receive, via the waveguide, a reflected wave group formed by reflecting the sweep wave group, which is included in the microwaves transmitted to the waveguide by the modulation unit and provided into the chamber via the antenna, by plasma in the chamber, and to demodulate the reflected wave group; The control device obtaining a first frequency of a sweep wave having the lowest reflectivity among the sweep waves based on the reflected wave group, and controlling the microwave output device to output the output wave of the first frequency; and when it is determined that the first frequency acquired at a first timing is not within a preset band, the microwave output device is controlled to output the output wave of the first frequency acquired at the first timing. Plasma processing equipment.

3. A chamber, a microwave output device configured to output microwaves that are provided into the chamber via a waveguide and an antenna; a control device configured to control the operation of the microwave output device; Equipped with the microwaves output by the microwave output device include an output wave for transmitting power used for plasma generation and a broadband sweep wave group used for detecting a plasma state in the chamber; the microwave output device includes a modulation unit configured to modulate the microwaves and transmit them to the waveguide, and a demodulation unit configured to receive, via the waveguide, a reflected wave group formed by reflecting the sweep wave group, which is included in the microwaves transmitted to the waveguide by the modulation unit and provided into the chamber via the antenna, by plasma in the chamber, and to demodulate the reflected wave group; The control device obtaining a first frequency of a sweep wave having the lowest reflectivity among the sweep waves based on the reflected wave group, and controlling the microwave output device to output the output wave of the first frequency; and controlling the microwave output device so as to output a plurality of output waves each having a plurality of first frequencies obtained at a plurality of timings. Plasma processing equipment.

4. The power of the output wave is 5000 W or less, and the frequency of the output wave is 2400 MHz to 2500 MHz. The plasma processing apparatus according to any one of claims 1 to 3.

5. The power of the sweep waves included in the sweep wave group is less than the power of the output wave and is 50 W or less. The plasma processing apparatus according to any one of claims 1 to 3.

6. The power of the output wave is 5000 W or less, and the frequency of the output wave is 2400 MHz to 2500 MHz, The power of the sweep waves included in the sweep wave group is less than the power of the output wave and is 50 W or less. The plasma processing apparatus according to any one of claims 1 to 3.

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