Plasma processing apparatus and resonance frequency measuring method

Abstract

To stably increase the density of plasma through resonance.SOLUTION: A plasma processing device includes a processing container, an electromagnetic wave generator, a resonant structure, a measurement unit, and a control unit. The processing container provides a processing space. The electromagnetic wave generator generates electromagnetic waves that are supplied to the processing space. The resonant structure is formed by arranging a plurality of resonators capable of resonating with the magnetic field component of the electromagnetic wave and whose size is smaller than the wavelength of the electromagnetic wave, and is located within the processing container. The measurement unit measures the power of the electromagnetic wave traveling from the electromagnetic wave generator to the resonant structure, and the power of the transmitted wave, reflected wave, or scattered wave of the electromagnetic wave in the resonant structure, for each frequency. The control unit executes a measurement process of measuring the power of the electromagnetic wave and the power of the transmitted wave, reflected wave or scattered wave by the measurement unit before execution of the plasma treatment, and a calculation process of calculating the resonant frequency of the resonant structure on the basis of the frequency distribution of the characteristic values of the resonant structure, which is calculated from the power of the electromagnetic wave and the power of the transmitted wave, reflected wave, or scattered wave.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a plasma processing apparatus and a method for measuring a resonant frequency. [Background technology]

[0002] Patent Document 1 discloses a plasma processing apparatus that generates plasma by supplying microwaves for plasma excitation into a processing chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-245593 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can stably increase the density of plasma through resonance. [Means for solving the problem]

[0005] A plasma processing apparatus according to one aspect of the present disclosure includes a processing vessel, an electromagnetic wave generator, a resonant structure, a measurement unit, and a control unit. The processing vessel provides a processing space where plasma processing is performed. The electromagnetic wave generator generates electromagnetic waves to be supplied to the processing space. The resonant structure is formed by arranging multiple resonators that can resonate with the magnetic field component of the electromagnetic waves and have a size smaller than the wavelength of the electromagnetic waves, and is located within the processing vessel. The measurement unit measures the power of the electromagnetic waves traveling from the electromagnetic wave generator to the resonant structure, and the power of transmitted, reflected, or scattered waves of the electromagnetic waves at the resonant structure for each frequency. Before performing plasma processing, the control unit performs a measurement process in which the measurement unit measures the power of the electromagnetic waves and the power of the transmitted, reflected, or scattered waves, and a calculation process in which the control unit calculates a resonant frequency of the resonant structure based on a frequency distribution of a characteristic value of the resonant structure calculated from the power of the electromagnetic waves and the power of the transmitted, reflected, or scattered waves. [Effects of the Invention]

[0006] According to the present disclosure, plasma density can be stably increased by resonance. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a microwave output device, a measuring instrument, and a tuner in the first embodiment. [Figure 3] FIG. 3 is a block diagram showing an example of the details of the waveform generating unit. [Figure 4] FIG. 4 is a plan view showing an example of the configuration of the dielectric window and the resonant structure according to the first embodiment, viewed from below. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of the first resonator according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the configuration of the second resonator according to the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of the configuration of the third resonator according to the first embodiment. [Figure 8] FIG. 8 is a diagram showing another example of the configuration of the third resonator according to the first embodiment. [Figure 9] FIG. 9 is a diagram showing an example of dimensions of a resonator of a resonant structure used in the verification. [Figure 10] FIG. 10 is a diagram showing an example of the relationship between the outer diameter of the ring member and the theoretical value of the resonant frequency of the resonator included in the resonant structure. [Figure 11] FIG. 11 is a diagram showing an example of the relationship between the thickness of the dielectric plate and the theoretical value of the resonance frequency of the resonator included in the resonance structure. [Figure 12] FIG. 12 is a diagram showing an example of the relationship between the relative dielectric constant of a dielectric plate and the theoretical value of the resonant frequency of a resonator included in a resonant structure. [Figure 13]FIG. 13 is a diagram showing an example of a frequency distribution of the transmission characteristic value (S21 value) of the resonant structure. [Figure 14] FIG. 14 is a diagram for explaining the deviation between the resonant frequency determined based on the design value and the actual resonant frequency in the processing chamber. [Figure 15] FIG. 15 is a flowchart showing the procedure of the process executed by the plasma processing apparatus according to the first embodiment. [Figure 16] FIG. 16 is a flowchart showing another example of the procedure of the process executed by the plasma processing apparatus according to the first embodiment. [Figure 17] FIG. 17 is a flowchart showing another example of the procedure of the process executed by the plasma processing apparatus according to the first embodiment. [Figure 18] FIG. 18 is a diagram showing an example of the configuration of a microwave output device, a measuring instrument, and a tuner in the second embodiment. [Figure 19] FIG. 19 is a flowchart illustrating an example of a procedure of a process performed by the plasma processing apparatus according to the second embodiment. [Figure 20] FIG. 20 is a diagram showing an example of the configuration of a microwave output device, a measuring instrument, and a tuner in the third embodiment. [Figure 21] FIG. 21 is a flowchart showing an example of a procedure of a process executed by the plasma processing apparatus according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the plasma processing apparatus and the resonant frequency measurement method disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed plasma processing apparatus and the resonant frequency measurement method are not limited to the present embodiments. Furthermore, each embodiment can be appropriately combined within a range that does not cause contradiction. Note that the same or equivalent parts in each drawing are assigned the same reference numerals.

[0009] In a plasma processing apparatus using microwaves for plasma excitation, the power of the microwaves supplied to the processing chamber may be increased to increase the electron density of the plasma. The higher the power of the microwaves supplied to the processing chamber, the higher the electron density of the plasma.

[0010] It is known that when the plasma electron density reaches a certain upper limit by increasing the microwave power supplied into the processing vessel, the dielectric constant of the space within the processing vessel becomes negative. This upper limit of electron density is appropriately referred to as the "cutoff density." The refractive index is also known as an index indicating whether microwaves propagate through space. The refractive index N is expressed by the following equation (1): N=√ε√μ (1) where ε is the permittivity and μ is the magnetic permeability

[0011] Since magnetic permeability is generally positive, if the dielectric constant of the space within the processing vessel becomes negative, the refractive index of the space within the processing vessel becomes a pure imaginary number according to the above formula (1). This causes microwaves to attenuate and become unable to propagate through the space within the processing vessel. When the plasma electron density reaches the cutoff density, microwaves cannot propagate through the space within the processing vessel, and therefore microwave power is not sufficiently absorbed by the plasma. As a result, there is a problem in that the plasma generated within the processing vessel is prevented from becoming highly dense over a wide area.

[0012] In response to this issue, a technology has been developed that uses a negative refractive index to increase plasma density by providing a resonant structure formed by arranging multiple resonators capable of resonating with microwaves within a processing vessel and resonating the resonant structure with microwaves. This technology allows microwaves to be efficiently supplied to the space within the processing vessel through the resonance of the resonant structure with microwaves, and also makes the magnetic permeability of the space within the processing vessel negative. When the magnetic permeability is negative, even if the electron density of the plasma generated in the space within the processing vessel reaches the cutoff density and the dielectric constant of the space within the processing vessel is negative, the refractive index becomes a negative real number according to the above equation (1), allowing microwaves to propagate within the space within the processing vessel. This allows microwaves to propagate beyond the plasma's skin depth even when the plasma's electron density reaches the cutoff density, and microwave power is efficiently absorbed by the plasma. As a result, high-density plasma can be generated over a wide area beyond the plasma's skin depth.

[0013] Resonance between the resonant structure and microwaves occurs when the frequency of the microwaves supplied into the processing vessel matches the resonant frequency of the resonant structure. Furthermore, resonance between the resonant structure and microwaves is maintained even in a predetermined frequency band higher than the resonant frequency of the resonant structure. Therefore, from the viewpoint of stably increasing the plasma density by resonance, it is important to accurately measure the resonant frequency of the resonant structure.

[0014] However, the resonant frequency of the resonant structure varies due to the influence of mechanical differences of the resonant structure (e.g., dimensional errors, assembly errors, etc.) and physical properties of the resonant structure (e.g., the dielectric constant of the dielectric material constituting the resonant structure). Furthermore, the resonant frequency of the resonant structure also varies depending on the environment in which the resonant structure is used (e.g., the temperature of the resonant structure). Therefore, even if the resonant frequency of the resonant structure is determined based on design values, the determined resonant frequency may differ from the actual resonant frequency of the resonant structure in the processing vessel. If the frequency of the microwaves supplied into the processing vessel deviates from the resonant frequency and a predetermined frequency band higher than the resonant frequency, the resonant structure and the microwaves do not resonate with each other, and therefore, the microwave power is not sufficiently absorbed by the plasma, which inhibits plasma densification.

[0015] Therefore, in the embodiment, the resonant frequency of the actual resonant structure installed in the processing vessel is measured before the plasma processing is performed in the processing vessel, which allows the resonant frequency of the resonant structure to be accurately measured without being affected by the mechanical difference of the resonant structure, thereby enabling stable plasma densification by resonance.

[0016] (First embodiment) [Configuration of plasma processing apparatus 1] 1 is a schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus 1 according to a first embodiment. The plasma processing apparatus 1 includes an apparatus main body 10 and a control device (an example of a control unit) 11. The apparatus main body 10 includes a processing vessel 12, a stage 14, a microwave output device (an example of an electromagnetic wave generator) 16, an antenna 18, a dielectric window 20, and a resonant structure 100.

[0017] The processing vessel 12 is formed in a substantially cylindrical shape from, for example, aluminum whose surface is anodized, and provides a substantially cylindrical processing space S therein. The processing vessel 12 is safety grounded. The processing vessel 12 has a sidewall 12a and a bottom 12b. The central axis of the sidewall 12a is defined as axis Z. The bottom 12b is provided on the lower end side of the sidewall 12a. The bottom 12b is provided with an exhaust port 12h for exhaust. The upper end of the sidewall 12a is open.

[0018] An opening 12c is formed in the side wall 12a for carrying in and out a substrate WP to be processed. The opening 12c is opened and closed by a gate valve G.

[0019] A dielectric window 20 is provided at the upper end of the side wall 12a, and the dielectric window 20 covers the opening at the upper end of the side wall 12a from above. A lower surface (an example of a first surface) 20a of the dielectric window 20 (an example of a dielectric) faces the processing space S. That is, the dielectric window 20 is provided with the lower surface 20a facing the processing space S. An O-ring 19 is arranged between the dielectric window 20 and the upper end of the side wall 12a.

[0020] The stage 14 is housed in the processing vessel 12. The stage 14 is disposed so as to face the dielectric window 20 in the direction of the axis Z. The space between the stage 14 and the dielectric window 20 is the processing space S. A substrate WP is placed on the stage 14.

[0021] The stage 14 includes a base 14a and an electrostatic chuck 14c. The base 14a is made of a conductive material such as aluminum and has a generally disk-like shape. The base 14a is disposed in the processing chamber 12 such that the central axis of the base 14a is generally aligned with the axis Z.

[0022] The base 14a is supported by a cylindrical support 48 made of an insulating material and extending in the direction of the axis Z. A conductive cylindrical support 50 is provided on the outer periphery of the cylindrical support 48. The cylindrical support 50 extends from the bottom 12b of the processing vessel 12 toward the dielectric window 20 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.

[0023] An annular baffle plate 52 having a plurality of through holes formed in the thickness direction is provided above the exhaust path 51. The above-mentioned exhaust port 12h is provided below the baffle plate 52. An exhaust device 56 having a vacuum pump such as a turbomolecular pump and an automatic pressure control valve is connected to the exhaust port 12h via an exhaust pipe 54. The exhaust device 56 can reduce the pressure in the processing space S to a desired vacuum level.

[0024] The base 14a functions as a radio-frequency electrode. A radio-frequency power supply 58 for RF 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 supplies, via the matching unit 60 and the power feed rod 62, to the base 14a, bias power of a predetermined frequency (e.g., 13.56 MHz) suitable for controlling the energy of ions attracted to the substrate WP.

[0025] The matching unit 60 contains a matching box 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 processing chamber 12. The matching box contains a blocking capacitor for generating a self-bias.

[0026] An electrostatic chuck 14c is provided on the upper surface of the base 14a. The electrostatic chuck 14c is disposed on the upper surface of the base 14a so that the central axis of the electrostatic chuck 14c substantially coincides with the axis Z. The electrostatic chuck 14c attracts and holds the substrate WP by electrostatic force. The electrostatic chuck 14c has a substantially disc-shaped outer shape and includes an electrode 14d, an insulating film (dielectric film) 14e, and an insulating film (dielectric film) 14f. The electrode 14d of the electrostatic chuck 14c is formed 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 coated wire 68 and a switch 66. The electrostatic chuck 14c can attract and hold the substrate WP on its upper surface by electrostatic force generated by a DC voltage applied from the DC power supply 64. An edge ring 14b is also provided on the base 14a. The edge ring 14b is disposed to surround the substrate WP and the electrostatic chuck 14c. The edge ring 14b is also called a focus ring.

[0027] A flow path 14g is provided inside the base 14a. A coolant is supplied to the flow path 14g from a chiller unit (not shown) via a pipe 70. The coolant supplied to the flow path 14g is returned to the chiller unit via a pipe 72. The coolant, whose temperature is controlled by the chiller unit, circulates through the flow path 14g of the base 14a, thereby controlling the temperature of the base 14a. By controlling the temperature of the base 14a, the temperature of the substrate WP on the electrostatic chuck 14c is controlled via the electrostatic chuck 14c on the base 14a.

[0028] Furthermore, the stage 14 is provided with a pipe 74 for supplying a heat transfer gas such as He gas between the upper surface of the electrostatic chuck 14c and the rear surface of the substrate WP.

[0029] The microwave output device 16 outputs microwaves (an example of electromagnetic waves) for exciting the processing gas supplied into the processing chamber 12. The microwave output device 16 is capable of adjusting the frequency, power, bandwidth, etc. of the microwaves. For example, the microwave output device 16 can generate microwaves containing a single frequency component (hereinafter referred to as "SP (Single Peak) microwaves") by setting the microwave bandwidth to approximately 0. The microwave output device 16 can also generate microwaves containing multiple frequency components belonging to a predetermined frequency bandwidth (hereinafter referred to as "BB (Broad Band) microwaves"). The power of these multiple frequency components may be the same, or only the central frequency component within the band may have a higher power than the power of the other frequency components. The microwave output device 16 can adjust the microwave power, for example, within a range of 0 W to 5000 W. The microwave output device 16 can adjust the frequency of the microwave or the central frequency of the BB microwave within a range of, for example, 2.3 GHz to 2.5 GHz, and can adjust the bandwidth of the BB microwave within a range of, for example, 0 MHz to 100 MHz. Furthermore, the microwave output device 16 can adjust the frequency pitch (carrier pitch) of the multiple frequency components of the BB microwave within a range of, for example, 0 to 25 kHz.

[0030] The device main body 10 also includes a waveguide 21, a measuring instrument (an example of a measuring unit) 22, a tuner 26, a mode converter 27, and a coaxial waveguide 28. The output unit 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.

[0031] Measuring instrument 22 is connected to waveguide 21 via directional coupler 22a provided in waveguide 21. Directional coupler 22a branches a portion of microwaves traveling from microwave output device 16 toward processing vessel 12 (i.e., traveling waves) and outputs the portion of the traveling waves to measuring instrument 22. Measuring instrument 22 measures the power of the traveling waves propagating through waveguide 21 for each frequency based on the portion of the traveling waves output from directional coupler 22a, and outputs the measurement results to control device 11. Measuring instrument 22 also measures the power of microwaves (i.e., transmitted waves) that pass through resonant structure 100 and return from the processing vessel 12 via waveguide 22b (see FIG. 2 ), which will be described later, for each frequency, and outputs the measurement results to control device 11.

[0032] Tuner 26 is provided in waveguide 21. Tuner 26 has movable plates 26a and 26b. By adjusting the amount of protrusion of each of movable plates 26a and 26b with respect to the internal space of waveguide 21, it is possible to match the impedance of microwave output device 16 with the impedance of the load.

[0033] The mode converter 27 converts the mode of the microwaves output from the waveguide 21 and supplies the mode-converted microwaves to the coaxial waveguide 28. The coaxial waveguide 28 includes an outer conductor 28a and an inner conductor 28b. The outer conductor 28a and the inner conductor 28b have a substantially cylindrical shape. The outer conductor 28a and the inner conductor 28b are arranged above the antenna 18 so that the central axes of the outer conductor 28a and the inner conductor 28b substantially coincide with the axis Z. The coaxial waveguide 28 transmits the microwaves whose mode has been converted by the mode converter 27 to the antenna 18.

[0034] The antenna 18 supplies microwaves into the processing chamber 12. The antenna 18 is an example of an electromagnetic wave supply unit. The antenna 18 is provided on the upper surface 20b of the dielectric window 20 and supplies microwaves to the processing space S through the dielectric window 20. The antenna 18 includes a slot plate 30, a dielectric plate 32, and a cooling jacket 34. The slot plate 30 is formed in a substantially circular plate shape using a conductive metal. The slot plate 30 is provided on the upper surface 20b of the dielectric window 20 so that the central axis of the slot plate 30 coincides with the axis Z. The slot plate 30 has multiple slot holes 30a formed therein. The multiple slot holes 30a form, for example, multiple slot pairs. Each of the multiple slot pairs includes two slot holes 30a each having an elongated shape extending in directions intersecting each other. The multiple slot pairs are arranged along one or more concentric circles around the central axis of the slot plate 30. In addition, a through hole 30d is formed in the center of the slot plate 30, through which a conduit 36 ​​(described later) can pass.

[0035] The dielectric plate 32 is formed in a substantially disk shape from a dielectric material such as quartz. The dielectric plate 32 is provided on the slot plate 30 so that 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.

[0036] The surface of the cooling jacket 34 is conductive. A flow path 34a is formed inside the cooling jacket 34. A refrigerant is supplied to the flow path 34a from a chiller unit (not shown). 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 openings formed in the center of the cooling jacket 34 and the dielectric plate 32.

[0037] The microwaves propagated through the coaxial waveguide 28 propagate through the dielectric plate 32 and are radiated into the processing space S from the plurality of slot holes 30 a of the slot plate 30 via the dielectric window 20 .

[0038] A conduit 36 ​​is provided inside the inner conductor 28b of the coaxial waveguide 28. 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 inside of the inner conductor 28b and is connected to a gas supply unit 38.

[0039] The gas supply unit 38 supplies a process gas for processing the substrate WP to the conduit 36. The gas supply unit 38 includes a gas supply source 38a, a valve 38b, and a flow rate controller 38c. The gas supply source 38a is a supply source of the process gas. The valve 38b controls the supply and stop of the process gas from the gas supply source 38a. The flow rate controller 38c is, for example, a mass flow controller, and controls the flow rate of the process gas supplied from the gas supply source 38a to the conduit 36.

[0040] An injector 41 is provided in the dielectric window 20. 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 sprayed into the processing space S and excited by microwaves radiated from the dielectric window 20 into the processing space S. As a result, the processing gas is converted into plasma in the processing space S, and the substrate WP on the electrostatic chuck 14c is processed by ions, radicals, and the like contained in the plasma.

[0041] The resonant structure 100 is formed by arranging a plurality of resonators that can resonate with the magnetic field component of microwaves and have a size smaller than the wavelength of the microwaves, and is located inside the processing vessel 12.

[0042] By positioning the resonant structure 100 within the processing vessel 12, microwaves supplied to the processing space S by the antenna 18 can be resonated with the resonant structure 100. Resonance between the microwaves and the resonant structure 100 allows the microwaves to be efficiently supplied to the processing space S of the processing vessel 12 and the magnetic permeability of the processing space S to be negative. When the magnetic permeability of the processing space S is negative, even if the electron density of the plasma generated in the processing space S reaches the cutoff density and the dielectric constant of the processing space S is negative, the refractive index becomes a real number according to the above formula (1), allowing the microwaves to propagate in the processing space S. This allows the microwaves to propagate beyond the skin depth of the plasma even when the electron density of the plasma generated in the processing space S reaches the cutoff density, and the microwave power is efficiently absorbed by the plasma. As a result, high-density plasma can be generated over a wide area beyond the skin depth of the plasma. That is, according to the plasma processing apparatus 1 of this embodiment, the positioning of the resonant structure 100 within the processing vessel 12 allows high-density plasma to be generated over a wide area. The detailed configuration of the resonant structure 100 will be described later.

[0043] The control device 11 has a processor, a memory, and an input / output interface. The memory stores programs, process recipes, etc. The processor reads and executes the programs from the memory, thereby controlling each part of the device main body 10 via the input / output interface based on the process recipes stored in the memory.

[0044] [Details of the microwave output device 16, measuring instrument 22, and tuner 26] 2 is a diagram showing an example of the configuration of the microwave output device 16, measuring device 22, and tuner 26 in the first embodiment. The microwave output device 16 has a microwave generating unit 16a, a waveguide 16b, a circulator 16c, a waveguide 16d, a waveguide 16e, a directional coupler 16f, a measuring device 16g, a directional coupler 16h, a measuring device 16i, and a dummy load 16j. The microwave generating unit 16a has a waveform generating unit 161, a power control unit 162, an attenuator 163, an amplifier 164, an amplifier 165, and a mode converter 166.

[0045] Waveform generating unit 161 generates SP microwaves or BB microwaves in a predetermined frequency range (for example, 2.4 GHz to 2.5 GHz). SP microwaves have a single peak (frequency component) at a specified frequency. BB microwaves have a specified bandwidth at a specified center frequency. Furthermore, waveform generating unit 161 can sweep the frequency of a single frequency component of the SP microwave from a specified frequency to a specified frequency at a specified sweep speed.

[0046] 3 is a block diagram showing an example of the details of the waveform generating unit 161. The waveform generating unit 161 includes, for example, a PLL (Phase Locked Loop) oscillator that outputs a microwave, and an IQ digital modulator connected to the PLL oscillator. The waveform generating unit 161 sets the frequency of the microwave output from the PLL oscillator to a frequency within a set frequency range specified by the control device 11. Then, the waveform generating unit 161 modulates the microwave output from the PLL oscillator and a microwave having a phase difference of 90° with respect to the microwave output from the PLL oscillator using the IQ digital modulator. In this way, the waveform generating unit 161 generates a microwave having a frequency within the set frequency range.

[0047] The waveform generating unit 161 can generate frequency-modulated microwaves by sequentially inputting N pieces of waveform data from a start frequency to an end frequency according to the scanning speed, and performing quantization and inverse Fourier transform.

[0048] In this embodiment, the waveform generating unit 161 has waveform data represented by a sequence of pre-digitized codes. The waveform generating unit 161 quantizes the waveform data and applies an inverse Fourier transform to the quantized data to generate I data and Q data. The waveform generating unit 161 then converts each of the I data and Q data, which are digital signals, into analog signals. The waveform generating unit 161 then extracts low-frequency components from each of the converted analog signals using an LPF (Low Pass Filter). The waveform generating unit 161 then mixes the I component analog signal with a microwave output from a PLL, and mixes the Q component analog signal with a microwave output from the PLL that has a phase difference of 90°. The waveform generating unit 161 then synthesizes the two mixed analog signals to generate a frequency-modulated microwave.

[0049] The method of generating microwaves by waveform generating section 161 is not limited to the method exemplified in FIG. 3, and microwaves may be generated using a DDS (Direct Digital Synthesizer) and a VCO (Voltage Controlled Oscillator).

[0050] Returning to FIG. 2 , the explanation will continue. The microwave output from the waveform generating unit 161 is input to the attenuator 163. The power control unit 162 is connected to the attenuator 163. The power control unit 162 may be, for example, a processor. The power control unit 162 controls the attenuation rate in the attenuator 163 so that microwaves having the power specified by the control device 11 are output from the microwave output device 16. The microwaves output from the attenuator 163 are output to the mode converter 166 via amplifiers 164 and 165. The amplifiers 164 and 165 amplify the microwaves at a set amplification rate. The mode converter 166 converts the mode of the microwaves amplified by the amplifier 165.

[0051] The output end of microwave generating unit 16a is connected to one end of waveguide 16b. The other end of waveguide 16b is connected to first port 261 of circulator 16c. A directional coupler 16f is provided in waveguide 16b. Note that directional coupler 16f may be provided in waveguide 16d. Directional coupler 16f branches a portion of the microwave (i.e., traveling wave) that is output from microwave generating unit 16a and propagates to circulator 16c, and outputs the portion of the traveling wave to measuring unit 16g. Measuring unit 16g measures the power of the traveling wave propagating through waveguide 16d based on the portion of the traveling wave output from directional coupler 16f, and outputs the measurement result to power control unit 162.

[0052] The circulator 16c has a first port 261, a second port 262, and a third port 263. The circulator 16c outputs microwaves input to the first port 261 from the second port 262, and outputs microwaves input to the second port 262 from the third port 263. One end of a waveguide 16d is connected to the second port 262 of the circulator 16c. The other end of the waveguide 16d is provided with an output end 16t of the microwave output device 16.

[0053] One end of waveguide 16e is connected to third port 263 of circulator 16c, and the other end of waveguide 16e is connected to dummy load 16j. Waveguide 16e is provided with directional coupler 16h. Note that directional coupler 16h may be provided in waveguide 16d. Directional coupler 16h branches a portion of the microwaves propagating through waveguide 16e (i.e., reflected waves) and outputs the portion of the reflected waves to measuring instrument 16i. Measuring instrument 16i measures the power of the reflected waves propagating through waveguide 16d based on the portion of the reflected waves output from directional coupler 16h, and outputs the measurement result to power control unit 162.

[0054] The dummy load 16j receives the microwaves propagating through the waveguide 16e and absorbs the microwaves, for example, by converting the microwaves into heat.

[0055] The power control unit 162 controls the waveform generating unit 161 and the attenuator 163 so that the difference between the power of the forward wave measured by the measuring instrument 16g and the power of the reflected wave measured by the measuring instrument 16i becomes the power specified by the control device 11. The difference between the power of the forward wave measured by the measuring instrument 16g and the power of the reflected wave measured by the measuring instrument 16i is the power supplied to the processing vessel 12.

[0056] The tuner 26 is provided in the waveguide 21 and adjusts the protruding position of the movable plate based on a control signal from the control device 11 so as to match the impedance on the microwave output device 16 side with the impedance on the processing chamber 12 side. The tuner 26 operates the movable plate using a driver circuit and an actuator (not shown). The adjustment of the protruding position of the movable plate may be achieved by a stub structure.

[0057] Measuring instrument 22 is connected to waveguide 21 via directional coupler 22a provided in waveguide 21. Directional coupler 22a branches a part of the microwaves (i.e., traveling waves) traveling from microwave output device 16 toward processing vessel 12, and outputs the part of the traveling waves to measuring instrument 22. Measuring instrument 22 measures the power of the traveling waves propagating through waveguide 21 for each frequency based on the part of the traveling waves output from directional coupler 22a, and outputs the measurement results to control device 11.

[0058] Furthermore, the measuring instrument 22 is connected to the power feed rod 62 in the processing chamber 12 via the waveguide 22b. The waveguide 22b branches a part of the microwaves (i.e., transmitted waves) that are transmitted through the resonant structure 100 and propagate to the stage 14 and the power feed rod 62, and returns the part of the transmitted waves from the processing chamber 12 to the measuring instrument 22. The measuring instrument 22 measures the power of the transmitted waves that are transmitted through the resonant structure 100 for each frequency, based on the part of the transmitted waves returned from the waveguide 22b, and outputs the measurement results to the control device 11.

[0059] Waveguide 22b is provided with filter 22c and attenuator 22d. Filter 22c removes noise components from the microwaves propagating through waveguide 22b. Attenuator 22d attenuates the microwaves propagating through waveguide 22b at a set attenuation rate.

[0060] [Details of the resonant structure 100] The detailed configuration of the resonant structure 100 will be described with reference to Fig. 1 and Fig. 4. Fig. 4 is a plan view showing an example of the configuration of the dielectric window 20 and the resonant structure 100 according to the first embodiment, viewed from below. In Fig. 4, the lower surface 20a of the dielectric window 20 is shown to be disk-shaped.

[0061] As shown in FIGS. 1 and 4, the resonant structure 100 is disposed along the lower surface 20 a of the dielectric window 20 .

[0062] The resonant structure 100 is formed by arranging a plurality of resonators 101 in a lattice pattern. The resonators 101 are capable of resonating with the magnetic field component of microwaves and have a size smaller than the wavelength of the microwaves. Specifically, the plurality of resonators 101 include at least one of a first resonator 101A, a second resonator 101B, and a third resonator 101C shown in FIGS. 5 to 7. Each of the plurality of resonators 101 forms a series resonant circuit made up of a capacitor equivalent element and a coil equivalent element. The series resonant circuit is realized by patterning a conductor on a plane.

[0063] Fig. 5 is a diagram showing an example of the configuration of a first resonator 101A according to the first embodiment. The first resonator 101A shown in Fig. 5 has a structure in which two C-shaped ring members 111A made of a conductor and arranged concentrically and facing in opposite directions are stacked on one surface of a dielectric plate 112A. Capacitor-equivalent elements are formed on the opposing surfaces of the inner and outer ring members 111A and on both ends of each ring member 111A, and coil-equivalent elements are formed along each ring member 111A. This allows the first resonator 101A to form a series resonant circuit.

[0064] FIG. 6 is a diagram showing an example of the configuration of a second resonator 101B according to the first embodiment. The second resonator 101B shown in FIG. 6 has a structure in which a dielectric plate 112B is sandwiched between both ends of a C-shaped ring member 111B made of a conductor. Capacitor-equivalent elements are formed at both ends of the ring member 111B, and a coil-equivalent element is formed along the ring member 111B. This allows the second resonator 101B to form a series resonant circuit. Note that in the second resonator 101B shown in FIG. 6, another dielectric plate different from the dielectric plate 112B may be joined to one surface of the ring member 111B.

[0065] FIG. 7 is a diagram illustrating an example of the configuration of a third resonator 101C according to the first embodiment. The third resonator 101C illustrated in FIG. 7 has a structure in which a dielectric plate 112C is disposed between two C-shaped ring members 111C made of a conductor and arranged adjacent to each other and facing in opposite directions. That is, in the third resonator 101C, the dielectric plate 112C is sandwiched between the two C-shaped ring members 111C facing in opposite directions. Capacitor-equivalent elements are formed on the opposing surfaces of the two C-shaped ring members 111C and at both ends of each ring member 111C, and coil-equivalent elements are formed along each ring member 111C. This allows the third resonator 101C to form a series resonant circuit.

[0066] In the third resonator 101C shown in FIG. 7, the number of arranged ring members 111C (hereinafter also referred to as the "number of layers") is two, but the number of layers of the ring members 111C may be greater than two. FIG. 8 is a diagram showing another example of the configuration of the third resonator 101C according to the first embodiment. The third resonator 101C shown in FIG. 8 has n (n≧2) C-shaped ring members 111C made of a conductor, and has a structure in which a dielectric plate 112C is disposed between the ring members 111C that are adjacently arranged in opposite directions. With such a structure, the third resonator 101C can also form a series resonant circuit.

[0067] [Change in Resonant Frequency of Resonator Included in Resonant Structure 100] Next, changes in the resonant frequency of the resonant structure 100 will be described with reference to Figs. 9 to 12. As described above, the resonant frequency of the resonant structure 100 changes due to the influence of the mechanical differences of the resonant structure 100 (e.g., dimensional errors, assembly errors, etc.) and the physical properties of the resonant structure 100 (e.g., the dielectric constant of the dielectric material constituting the resonant structure 100). This is thought to be because the resonant frequency of the resonators included in the resonant structure 100 changes due to the influence of the mechanical differences and physical properties of the resonators. The inventors have verified, using a theoretical formula, changes in the theoretical value of the resonant frequency when the mechanical differences and physical properties of the resonators included in the resonant structure 100 are changed.

[0068] Fig. 9 is a diagram showing an example of dimensions of a resonator of the resonant structure 100 used for the verification. The resonator used for the verification is the third resonator 101C shown in Fig. 7. Various dimensions and physical property values ​​of the third resonator 101C are defined as follows. w: width of ring member 111C g: Distance between both ends of the ring member 111C r: radius of ring member 111C r out :Outer diameter of ring member 111C r in : Inner diameter of ring member 111C d: thickness of dielectric plate 112C ε: relative permittivity of dielectric plate 112C

[0069] The theoretical value f of the resonant frequency of the third resonator 101C r0 is expressed by the following equation (2). f r0 =1 / (2π√LC) (2) where L is the inductance of the third resonator 101C, and C is the capacitance of the third resonator 101C.

[0070] The inductance L of the third resonator 101C is expressed by the following equation (3). L=μ0r(log(4π)−1) (3) where μ0 is the magnetic permeability of a vacuum

[0071] Furthermore, the capacitance C of the third resonator 101C is expressed by the following equations (4) and (5). C=1 / (1 / C half +1 / C half ) (4) C half =εε0(π(r out 2 -r in 2 )-gw) / (2d) ··· (5) where ε0 is the dielectric constant of a vacuum

[0072] Fig. 10 is a diagram showing an example of the relationship between the outer diameter of ring member 111C and the theoretical value of the resonant frequency of the resonator included in resonant structure 100. As shown in Fig. 10, the resonant frequency of the resonator included in resonant structure 100 changes in accordance with the change in the outer diameter of ring member 111C.

[0073] Fig. 11 is a diagram showing an example of the relationship between the thickness of the dielectric plate 112C and the theoretical value of the resonant frequency of the resonator included in the resonant structure 100. As shown in Fig. 11, the resonant frequency of the resonator included in the resonant structure 100 changes in accordance with the change in the thickness of the dielectric plate 112C.

[0074] Fig. 12 is a diagram showing an example of the relationship between the relative dielectric constant of the dielectric plate 112C and the theoretical value of the resonant frequency of the resonator included in the resonant structure 100. As shown in Fig. 12, the resonant frequency of the resonator included in the resonant structure 100 changes in accordance with the change in the relative dielectric constant of the dielectric plate 112C.

[0075] 10 to 12, it was confirmed that the resonant frequency of the resonator included in the resonant structure 100 changes due to the influence of the machine difference and physical property values ​​of the resonator. That is, it was confirmed that the resonant frequency of the resonant structure 100 changes due to the influence of the machine difference and physical property values ​​of the resonant structure 100.

[0076] [Frequency distribution of transmission characteristic values ​​of resonant structure 100] FIG. 13 shows the transmission characteristic value (S 2113 is a graph showing an example of a frequency distribution of the S value of the resonant structure 100 when the SP microwave is supplied to the processing space S in the processing container 12. 21 The S value of the resonant structure 100 is plotted for each frequency of the SP microwave. 21 The value is calculated by log(P2 / P1), where P1 is the power of the forward wave and P2 is the power of the transmitted wave.

[0077] In the example of FIG. 13, the frequency of the microwave supplied to the processing space S is equal to the resonant frequency f r (=approximately 2.35 GHz), the S 21 The value of the microwave frequency becomes a minimum value, and resonance occurs between the microwave and the resonant structure 100. The resonance between the microwave and the resonant structure 100 occurs at the resonant frequency f r A predetermined frequency band (e.g., resonant frequency f r The resonant frequency f of the resonant structure 100 is maintained even at frequencies in the range of 100 to about 0.1 GHz. r In a predetermined frequency band higher than , the resonance between the microwave and the resonant structure 100 can make both the permittivity and permeability of the processing space S negative, and as can be seen from the above equation (1), microwave propagation in the processing space S becomes possible.

[0078] Therefore, the resonant frequency f of the resonant structure 100 r If microwaves containing frequency components in a target frequency band (e.g., in the range of approximately 0.1 GHz) higher than the cutoff density are supplied to the processing space S in the processing vessel 12, the microwaves can be resonated with the resonant structure 100. Then, the resonance between the microwaves and the resonant structure 100 can make both the permittivity and permeability of the processing space S negative. Therefore, even when the electron density of the plasma reaches the cutoff density, the microwaves can propagate beyond the skin depth of the plasma, allowing the plasma to efficiently absorb the microwave power. As a result, the plasma can be stably densified by resonance.

[0079] However, the resonant frequency f of the resonant structure 100 rchanges due to the influence of mechanical differences of the resonant structure 100 (e.g., dimensional errors, assembly errors, etc.) and physical properties of the resonant structure 100 (e.g., the dielectric constant of the dielectric material constituting the resonant structure 100). As a result, the resonant frequency of the resonant structure 100 may differ between different plasma processing apparatuses 1. Furthermore, even in the same plasma processing apparatus 1, the resonant structure 100 may experience thermal expansion and contraction of each resonator due to the influence of the environment in which the resonant structure 100 is used (e.g., the temperature of the resonant structure 100), and the resonant frequency f of the resonant structure 100 may vary. r Therefore, the resonant frequency f of the resonant structure 100 is changed based on the design value. r Even if the resonant frequency f r and the resonant frequency f of the actual resonant structure 100 in the processing vessel. r There may be cases where the two are not aligned.

[0080] Figure 14 shows the resonant frequency f determined based on the design values. r1 and the actual resonant frequency f r2 14 is a graph for explaining the deviation from the resonant frequency f determined based on the design value. r1 The transmission characteristic value (S 21 Graph 502 in FIG. 14 is a graph showing the frequency distribution of the actual resonant frequency f r2 The transmission characteristic value (S 21 14 is a graph showing the frequency distribution of the actual resonant frequency f (value) in the processing chamber 12 depending on the machine error, physical property values, and usage environment of the resonant structure 100. r2 is the resonant frequency f determined based on the design value r1 And the resonant frequency f r1 and the resonant frequency f r2 This causes the resonance frequency f r1 The target frequency band B1 and the corresponding resonant frequency f r2When the microwave frequency deviates from the target frequency band due to such a change in the target frequency band, the microwave does not resonate with the resonant structure 100. As a result, the microwave power is not sufficiently absorbed by the plasma, and the plasma is prevented from becoming denser.

[0081] In contrast, the plasma processing apparatus 1 of this embodiment measures the resonant frequency of the actual resonant structure 100 installed in the processing vessel 12 before performing plasma processing in the processing vessel 12. This allows the plasma processing apparatus 1 to accurately measure the resonant frequency of the resonant structure 100 without being affected by mechanical differences of the resonant structure 100, and therefore to accurately determine the target frequency band corresponding to the resonant frequency. As a result, the plasma processing apparatus 1 can prevent the frequency of the microwave supplied to the processing space S in the processing vessel 12 from deviating from the target frequency band. Therefore, during plasma processing, the resonance between the microwave and the resonant structure 100 can maintain both the permittivity and permeability of the processing space S negative, thereby stably increasing the plasma density.

[0082] [Specific Operation of Plasma Processing Apparatus 1] Next, a specific operation of the plasma processing apparatus 1 according to the first embodiment will be described with reference to Fig. 15. Fig. 15 is a flowchart showing the procedure of the process executed by the plasma processing apparatus 1 according to the first embodiment. Note that each process shown in Fig. 15 is realized by the control device 11 controlling each part of the apparatus main body 10.

[0083] First, the control device 11 opens the valve 38b and controls the flow rate controller 38c so that a predetermined flow rate of the processing gas is supplied into the processing vessel 12, thereby starting the supply of the gas to the processing space S in the processing vessel 12 (step S101). Then, the control device 11 controls the exhaust device 56 to adjust the pressure in the processing vessel 12 (step S102).

[0084] Next, the control device 11 controls the microwave output device 16 to generate a first microwave and supply the first microwave to the processing space S in the processing vessel 12 via the antenna 18 (step S103). The first microwave is a microwave with a lower power than the microwave for plasma processing and is a microwave containing a single frequency component (i.e., an SP microwave). The control device 11 generates the SP microwave with a lower power than the microwave for plasma processing so as not to generate plasma in the processing space S.

[0085] Next, the control device 11 controls the microwave output device 16 to start sweeping the frequency of the single frequency component of the SP microwave (step S104).

[0086] Next, the control device 11 measures the power of the forward wave and the power of the transmitted wave using the measuring device 22 (step S105, measurement process). The control device 11 performs the measurement process in a state where no plasma is generated in the processing space S. In addition, the control device 11 performs the measurement process while sweeping the frequency of a single frequency component of the SP microwave.

[0087] Next, the control device 11 calculates the transmission characteristic value (S 21 Based on the frequency distribution of the resonant frequency f r (step S106, calculation process). The control device 11 calculates the transmission characteristic value (S 21 S of the resonant structure 100 in the frequency distribution of 21 The frequency at which the value is the minimum is defined as the resonant frequency f r It is calculated as follows.

[0088] The actual resonant frequency f in the processing vessel 12 varies depending on the machine error, physical properties, and usage environment of the resonant structure 100. r2 is the resonant frequency f determined based on the design value r1 (See Figure 14.) Then, the resonant frequency f r1 and the resonant frequency f r2This causes the resonance frequency f r1 The target frequency band B1 and the corresponding resonant frequency f r2 As a result, the frequency of the microwave deviates from the target frequency band B2 (see FIG. 14). When a microwave for plasma processing is generated and plasma processing of the substrate WP is started in a state in which the microwave frequency deviates from the target frequency band due to such a change in the target frequency band, the microwave does not resonate with the resonant structure 100. As a result, the power of the microwave is not sufficiently absorbed by the plasma, and the plasma is prevented from becoming highly dense.

[0089] Therefore, in the plasma processing apparatus 1 according to this embodiment, before the plasma processing is performed in the processing chamber 12, a measurement process and a calculation process are performed to obtain the resonance frequency f of the actual resonant structure 100 provided in the processing chamber 12. r As a result, the plasma processing apparatus 1 measures the resonant frequency f of the resonant structure 100 without being affected by the mechanical difference of the resonant structure 100. r can be accurately measured.

[0090] Next, the control device 11 calculates the resonance frequency f r As a result, the plasma processing apparatus 1 determines a predetermined frequency band higher than the resonant frequency f of the actual resonant structure 100 provided in the processing chamber 12 as the target frequency band (step S107). r Therefore, the target frequency band corresponding to the frequency band .theta.

[0091] Next, the supply of the processing gas into the processing vessel 12 is temporarily stopped, and the processing gas remaining in the processing vessel 12 is exhausted. Thereafter, the gate valve G is opened, and an unprocessed substrate WP is loaded into the processing vessel 12 through the opening 12c by a robot arm (not shown), and placed on the electrostatic chuck 14c (S108). Then, the gate valve G is closed. Then, the controller 11 opens the valve 38b and controls the flow rate controller 38c so that a predetermined flow rate of the processing gas is supplied into the processing vessel 12, thereby restarting the supply of the gas into the processing vessel 12. Then, the controller 11 controls the exhaust device 56 to adjust the pressure inside the processing vessel 12.

[0092] Next, the control device 11 controls the microwave output device 16 to generate a second microwave and supply the second microwave to the processing space S in the processing vessel 12 (step S109). The second microwave is a microwave for plasma processing that has a higher power than the first microwave. The second microwave may be either an SP microwave or a BB microwave. By supplying the second microwave to the processing space S in the processing vessel 12, plasma of the processing gas is generated, and plasma processing of the substrate WP is initiated. At this time, the electron density of the plasma reaches the cutoff density. When the electron density of the plasma reaches the cutoff density, microwaves cannot propagate in the processing space S in the processing vessel 12.

[0093] Therefore, the control device 11 controls the microwave output device 16 during the plasma processing to set the resonant frequency f r By generating a second microwave including a frequency component in a target frequency band higher than the resonant frequency f of the actual resonant structure 100 provided in the processing chamber 12, a resonance process is performed in which the second microwave resonates with the resonant structure 100. Here, the target frequency band is the resonant frequency f of the actual resonant structure 100 provided in the processing chamber 12. r Therefore, the resonant frequency f r By generating the second microwave including a frequency component in a target frequency band higher than the first microwave, it is possible to reliably resonate the second microwave with the resonant structure 100. As a result, the plasma density can be stably increased by resonance.

[0094] That is, due to the resonance between the second microwave and the resonant structure 100, both the permittivity and the permeability of the plasma in the processing space S can be made negative, and as can be seen from the above formula (1), the second microwave can propagate in the processing space S. As a result, in the processing space S inside the processing vessel 12, the second microwave can propagate beyond the skin depth of the plasma, and the power of the second microwave is efficiently injected into the plasma, resulting in the generation of high-density plasma over a wide area beyond the skin depth of the plasma.

[0095] Next, the control device 11 determines whether a predetermined time has elapsed since the supply of the second microwaves began (step S110). The predetermined time here is the time from the start of the supply of the second microwaves until the completion of plasma processing such as etching on the substrate WP. If the predetermined time has not elapsed (step S110: No), the process shown in step S109 is executed again.

[0096] On the other hand, if the predetermined time has elapsed (step S110: Yes), the controller 11 controls the microwave output device 16 to stop the supply of the second microwave (step S111). Then, the controller 11 closes the valve 38b to stop the supply of the processing gas into the processing vessel 12 (step S112). Then, the controller 11 controls the exhaust device 56 to exhaust the processing gas inside the processing vessel 12. Then, the gate valve G is opened, and the processed substrate WP is unloaded from the processing vessel 12 by a robot arm (not shown) (step S113). After the substrate WP has been unloaded, the controller 11 ends the series of operations in the plasma processing apparatus 1.

[0097] Next, a modified example of the specific operation of the plasma processing apparatus 1 shown in Fig. 15 will be described with reference to Fig. 16 and Fig. 17. Fig. 16 is a flowchart showing another example of the procedure of the process executed by the plasma processing apparatus 1 according to the first embodiment. Note that, except for the points described below, in the process illustrated in Fig. 16, the processes denoted by the same reference numerals as those in Fig. 15 are the same as the processes described using Fig. 15, and therefore detailed description thereof will be omitted.

[0098] After step S102, the control device 11 controls the microwave output device 16 to generate a third microwave and supply the third microwave to the processing space S in the processing vessel 12 via the antenna 18 (step S103a). The third microwave is a microwave (i.e., a BB microwave) that has a lower power than the microwave for plasma processing (i.e., the second microwave) and includes multiple frequency components that belong to a predetermined frequency bandwidth. The control device 11 generates the BB microwave that has a lower power than the microwave for plasma processing so as not to generate plasma in the processing space S.

[0099] Next, the control device 11 measures the power of the forward wave and the power of the transmitted wave using the measuring device 22 (step S105, measurement process). The control device 11 executes the measurement process in a state where no plasma is generated in the processing space S. Furthermore, the control device 11 executes the measurement process for each frequency of the multiple frequency components of the BB microwave. Then, the processes from step S106 onwards are executed.

[0100] According to this example, by using the BB microwave, the measurement process can be performed without sweeping the frequency, and the processing speed of the plasma processing apparatus 1 can be improved.

[0101] Fig. 17 is a flowchart showing another example of the procedure of the process executed by the plasma processing apparatus 1 according to the first embodiment. Note that, except for the points described below, in the process illustrated in Fig. 17, the processes denoted by the same reference numerals as those in Fig. 15 are the same as the processes described using Fig. 15, and therefore detailed description thereof will be omitted.

[0102] After step S102, the control device 11 controls the microwave output device 16 to generate a fourth microwave and supply the fourth microwave to the processing space S in the processing vessel 12 via the antenna 18 (step S121, heating process). The fourth microwave is a microwave having a power equal to or greater than the power of the microwave for plasma processing (i.e., the second microwave). The fourth microwave may be either an SP microwave or a BB microwave. By supplying the fourth microwave to the processing space S in the processing vessel 12, plasma of the processing gas is generated. Then, the generated plasma heats the resonant structure 100.

[0103] Next, the control device 11 determines whether a predetermined time has elapsed since the start of the heat treatment (step S122). The predetermined time here is the time from the start of the heat treatment until the thermal expansion of each resonator in the resonant structure 100 is completed, and is measured in advance by experiment or simulation. If the predetermined time has not elapsed (step S122: No), the process shown in step S121 is executed again.

[0104] On the other hand, if the predetermined time has elapsed (step S122: Yes), the control device 11 controls the microwave output device 16 to generate the first microwave instead of the fourth microwave (step S103), and then executes the processes from step S104 onwards, including the measurement process (step S105).

[0105] In this way, by performing a heating process before performing a measurement process, the resonators in the resonant structure 100 are thermally expanded, and the resonant frequency f r Therefore, even if thermal expansion of each resonator in the resonant structure 100 occurs when the second microwave is supplied to the processing space S in the processing vessel 12, the resonant frequency f r As a result, according to this example, the resonant frequency f of the resonant structure 100 can be kept constant while suppressing the influence of thermal expansion of each resonator in the resonant structure 100. rcan be measured with high accuracy.

[0106] (Second embodiment) In the first embodiment, the transmission characteristic value (S 21 Using the frequency distribution of the resonant frequency f r In contrast to this, in the second embodiment, the reflection characteristic value (S 11 Using the frequency distribution of the resonant frequency f r Calculate.

[0107] Fig. 18 is a diagram showing an example of the configuration of a microwave output device 16, a measuring device 22, and a tuner 26 in the second embodiment. Except for the points described below, in the configuration shown in Fig. 18, the parts denoted by the same reference numerals as in Fig. 2 are the same as the parts described using Fig. 2, and therefore detailed description thereof will be omitted.

[0108] In the plasma processing apparatus 1 according to the second embodiment, the measuring device 22 is connected to the waveguide 21 via a directional coupler 22a provided in the waveguide 21. The directional coupler 22a branches a portion of the microwaves traveling from the microwave output device 16 toward the processing chamber 12 (i.e., traveling waves) and outputs the portion of the traveling waves to the measuring device 22. The directional coupler 22a also branches a portion of the microwaves returning from the processing chamber 12 to the output end 16t of the microwave output device 16 (i.e., reflected waves) and outputs the portion of the reflected waves to the measuring device 22. The measuring device 22 measures the power of the traveling waves propagating through the waveguide 21 for each frequency based on the portion of the traveling waves output from the directional coupler 22a, and outputs the measurement results to the control device 11. The measuring device 22 also measures the power of the reflected waves propagating through the waveguide 21 for each frequency based on the portion of the reflected waves output from the directional coupler 22a, and outputs the measurement results to the control device 11.

[0109] Here, the reflection characteristic value (S 11 The frequency distribution of the S 11The value is calculated by log(P3 / P1), where P1 is the power of the forward wave and P3 is the power of the reflected wave. 11 The frequency distribution of the S 21 That is, when the frequency of the microwave supplied to the processing space S is equal to the resonant frequency f of the resonant structure 100, r (=approximately 2.35 GHz), the S 11 The value of the microwave frequency becomes a minimum value, and resonance occurs between the microwave and the resonant structure 100. The resonance between the microwave and the resonant structure 100 occurs at the resonant frequency f r A predetermined frequency band (e.g., resonant frequency f r This is maintained even at frequencies in the range from 0.1 GHz to approximately 0.1 GHz.

[0110] Next, a specific operation of the plasma processing apparatus 1 according to the second embodiment will be described with reference to Fig. 19. Fig. 19 is a flowchart showing an example of a procedure of a process executed by the plasma processing apparatus 1 according to the second embodiment. Note that, except for the points described below, in the process illustrated in Fig. 19, the processes denoted by the same reference numerals as those in Fig. 15 are the same as the processes described using Fig. 15, and therefore detailed description thereof will be omitted.

[0111] After step S104, the control device 11 measures the power of the forward wave and the power of the reflected wave using the measuring device 22 (step S105a, measurement process). The control device 11 performs the measurement process in a state where no plasma is generated in the processing space S. The control device 11 also performs the measurement process while sweeping the frequency of a single frequency component of the SP microwave.

[0112] Next, the control device 11 calculates the reflection characteristic value (S 11 Based on the frequency distribution of the resonant frequency f r (step S106a, calculation process). The control device 11 calculates the reflection characteristic value (S 11 S of the resonant structure 100 in the frequency distribution of11 The frequency at which the value is the minimum is defined as the resonant frequency f r Then, the processes from step S107 onwards are executed.

[0113] In this way, in the second embodiment, the reflection characteristic value (S 11 Using the frequency distribution of the resonant frequency f r As a result, the plasma processing apparatus 1 can calculate the resonant frequency f of the resonant structure 100 without being affected by the machine difference of the resonant structure 100. r can be accurately measured.

[0114] (Third embodiment) In the first embodiment, the transmission characteristic value (S 21 Using the frequency distribution of the resonant frequency f r In contrast to this, in the third embodiment, the power of the scattered waves scattered laterally from the resonant structure 100 is measured, and the transmission characteristic value (S 21 Using the frequency distribution of the resonant frequency f r Calculate.

[0115] Fig. 20 is a diagram showing an example of the configuration of a microwave output device 16, a measuring instrument 22, and a tuner 26 in the third embodiment. Except for the points described below, in the configuration shown in Fig. 20, the parts denoted by the same reference numerals as in Fig. 2 are the same as the parts described using Fig. 2, and therefore detailed description thereof will be omitted.

[0116] In the plasma processing apparatus 1 according to the third embodiment, the measuring device 22 is connected to the waveguide 21 via a directional coupler 22a provided in the waveguide 21. The directional coupler 22a branches a part of the microwaves (i.e., traveling waves) traveling from the microwave output device 16 toward the processing chamber 12, and outputs the part of the traveling waves to the measuring device 22. The measuring device 22 measures the power of the traveling waves propagating through the waveguide 21 for each frequency based on the part of the traveling waves output from the directional coupler 22a, and outputs the measurement results to the control device 11.

[0117] Furthermore, an antenna 23 is provided on the sidewall of the processing vessel 12, and the measuring instrument 22 is connected to the antenna 23 via a waveguide 22b. The antenna 23 protrudes into the processing vessel 12. The antenna 23 receives microwaves scattered laterally from the resonant structure 100 (i.e., scattered waves). The waveguide 22b returns the scattered waves received by the antenna 23 to the measuring instrument 22 from the processing vessel 12 side. The measuring instrument 22 measures the power of the scattered waves scattered laterally from the resonant structure 100 for each frequency based on the scattered waves returned from the waveguide 22b, and outputs the measurement results to the control device 11.

[0118] Here, the transmission characteristic value (S 21 The frequency distribution of the S 21 The value is calculated by log(P4 / P1), where P1 is the power of the forward wave and P4 is the power of the scattered wave. 21 The frequency distribution of the S 21 That is, when the frequency of the microwave supplied to the processing space S is equal to the resonant frequency f of the resonant structure 100, r (=approximately 2.35 GHz), the S 21 The value of the microwave frequency becomes a minimum value, and resonance occurs between the microwave and the resonant structure 100. The resonance between the microwave and the resonant structure 100 occurs at the resonant frequency f r A predetermined frequency band (e.g., resonant frequency f r This is maintained even at frequencies in the range from 0.1 GHz to approximately 0.1 GHz.

[0119] Next, a specific operation of the plasma processing apparatus 1 according to the third embodiment will be described with reference to Fig. 21. Fig. 21 is a flowchart showing an example of a procedure of a process executed by the plasma processing apparatus 1 according to the third embodiment. Note that, except for the points described below, in the process illustrated in Fig. 21, the processes denoted by the same reference numerals as those in Fig. 15 are the same as the processes described using Fig. 15, and therefore detailed description thereof will be omitted.

[0120] After step S104, the control device 11 measures the power of the progressive wave and the power of the scattered wave using the measuring device 22 (step S105b, measurement process). The control device 11 performs the measurement process in a state where no plasma is generated in the processing space S. The control device 11 also performs the measurement process while sweeping the frequency of a single frequency component of the SP microwave.

[0121] Next, the control device 11 calculates the transmission characteristic value (S 21 Based on the frequency distribution of the resonant frequency f r (step S106b, calculation process). The control device 11 calculates the transmission characteristic value (S 21 S of the resonant structure 100 in the frequency distribution of 21 The frequency at which the value is the minimum is defined as the resonant frequency f r Then, the processes from step S107 onwards are executed.

[0122] As described above, in the third embodiment, the power of the scattered waves scattered laterally from the resonant structure 100 is measured, and the transmission characteristic value (S 21 Using the frequency distribution of the resonant frequency f r As a result, the plasma processing apparatus 1 can calculate the resonant frequency f of the resonant structure 100 without being affected by the machine difference of the resonant structure 100. r can be accurately measured.

[0123] (Other variations) In the above embodiment, the measuring device 22 measures the power of the forward wave and the power of the transmitted wave, reflected wave, or scattered wave for each frequency. The disclosed technology is not limited to this, and the measurement of the power of the forward wave may be omitted. That is, the measuring device 22 may measure the power of the transmitted wave, reflected wave, or scattered wave for each frequency. In such a case, the control device 11 measures the power of the transmitted wave, reflected wave, or scattered wave using the measuring device 22 in the measurement process before performing the plasma process. Then, the control device 11 determines the resonant frequency f of the resonant structure 100 based on the frequency distribution of the power of the transmitted wave, reflected wave, or scattered wave. r Specifically, the control device 11 calculates the frequency at which the power of the transmitted wave, the reflected wave, or the scattered wave has a minimum value in the frequency distribution of the power of the transmitted wave, the reflected wave, or the scattered wave as the resonant frequency f of the resonant structure 100. r It is calculated as follows.

[0124] Here, when the power of the traveling wave does not change substantially with frequency, the frequency distribution of the power of the transmitted wave, the reflected wave, or the scattered wave is determined by the transmission characteristic value (S 21 value) or reflectance characteristic value (S 11 In this case, the control device 11 calculates the resonant frequency f using the frequency distribution of the power of the transmitted wave, the reflected wave, or the scattered wave without measuring the power of the traveling wave. r This allows the transmission characteristic value (S 21 value) or reflectance characteristic value (S 11 Using the frequency distribution of the resonant frequency f r This can reduce the processing load compared to when calculating

[0125] As described above, a plasma processing apparatus (e.g., plasma processing apparatus 1) according to an embodiment includes a processing vessel (e.g., processing vessel 12), an electromagnetic wave generator (e.g., microwave output device 16), a resonant structure (e.g., resonant structure 100), a measurement unit (e.g., measurement device 22), and a control unit (e.g., control device 11). The processing vessel provides a processing space (e.g., processing space S) where plasma processing is performed. The electromagnetic wave generator generates electromagnetic waves (e.g., microwaves) to be supplied to the processing space. The resonant structure is formed by arranging multiple resonators (e.g., resonator 101) that can resonate with the magnetic field component of the electromagnetic waves and have a size smaller than the wavelength of the electromagnetic waves, and is located inside the processing vessel. The measurement unit measures the power of the electromagnetic waves traveling from the electromagnetic wave generator to the resonant structure and the power of the transmitted, reflected, or scattered waves of the electromagnetic waves at the resonant structure for each frequency. The control unit performs a measurement process in which the power of the electromagnetic wave and the power of the transmitted wave, the reflected wave, or the scattered wave are measured by the measurement unit before the plasma processing is performed, and calculates a characteristic value of the resonant structure (for example, a transmission characteristic value (S 21 value) or reflectance characteristic value (S 11 Based on the frequency distribution of the resonant frequency of the resonant structure (e.g., the resonant frequency f r Therefore, according to the plasma processing apparatus of the embodiment, it is possible to stably increase the density of the plasma by resonance.

[0126] Furthermore, the control unit may perform a resonance process during plasma processing by controlling the electromagnetic wave generator to generate electromagnetic waves including frequency components in a target frequency band higher than the resonant frequency, thereby resonating the electromagnetic waves with the resonant structure, thereby generating high-density plasma over a wide range beyond the plasma skin depth.

[0127] Furthermore, the control unit may control the electromagnetic wave generator to generate electromagnetic waves with a lower power than that generated during plasma processing so as not to generate plasma in the processing space, and perform the measurement process in a state in which no plasma is generated in the processing space, thereby making it possible to perform the measurement process while eliminating the influence of plasma.

[0128] The control unit may also control the electromagnetic wave generator to generate electromagnetic waves (e.g., SP microwaves) that have a lower power than the electromagnetic waves generated during plasma processing and contain a single frequency component, and perform the measurement process while sweeping the frequency of the single frequency component of the electromagnetic waves. This allows the power of the electromagnetic waves and the power of the transmitted, reflected, or scattered waves to be quickly measured in a pre-specified frequency band.

[0129] The control unit may also control the electromagnetic wave generator to generate electromagnetic waves (e.g., BB microwaves) that have lower power than the electromagnetic waves generated during plasma processing and include multiple frequency components within a predetermined frequency bandwidth, and perform measurement processing for each frequency of the multiple frequency components of the electromagnetic waves. This allows the measurement processing to be performed without sweeping frequencies, thereby improving the processing speed of the plasma processing apparatus.

[0130] The control unit may control the electromagnetic wave generator to generate electromagnetic waves having a power equal to or greater than that of the electromagnetic waves generated during the plasma processing, thereby generating plasma in the processing space, and may perform a heating process to heat the resonant structure using the generated plasma. This makes it possible to measure the resonant frequency of the resonant structure with high accuracy while suppressing the influence of thermal expansion of each resonator in the resonant structure.

[0131] The plasma processing apparatus according to the embodiment may include a waveguide (e.g., waveguide 21) that guides the electromagnetic waves generated by the electromagnetic wave generator toward the processing space. In such a case, the measurement unit may measure the power of the electromagnetic waves propagating through the waveguide and the power of the reflected waves propagating through the waveguide for each frequency. This allows the power of the electromagnetic waves and the power of the reflected waves to be measured with high accuracy at a position closer to the processing space.

[0132] The resonant structure may be disposed along a first surface (e.g., the lower surface 20a) of a member that is provided with the first surface facing the processing space. This allows the resonant structure located at any position in the processing chamber to achieve high density plasma over a wide area.

[0133] The plasma processing apparatus according to the embodiment may further include a dielectric (e.g., a dielectric window 20) with a first surface (e.g., a lower surface 20a) facing the processing space, and an electromagnetic wave supply unit (e.g., an antenna 18) that supplies electromagnetic waves to the processing space via the dielectric. The resonant structure may be disposed along the first surface of the dielectric. This allows the power of the electromagnetic waves to be efficiently absorbed by the plasma, thereby facilitating the densification of the plasma over a wide area.

[0134] Furthermore, a plasma processing apparatus (e.g., plasma processing apparatus 1) according to an embodiment includes a processing vessel (e.g., processing vessel 12), an electromagnetic wave generator (e.g., microwave output device 16), a resonant structure (e.g., resonant structure 100), a measurement unit (e.g., measurement device 22), and a control unit (e.g., control device 11). The processing vessel provides a processing space (e.g., processing space S) where plasma processing is performed. The electromagnetic wave generator generates electromagnetic waves (e.g., microwaves) to be supplied to the processing space. The resonant structure is formed by arranging multiple resonators (e.g., resonator 101) that can resonate with the magnetic field component of the electromagnetic waves and have a size smaller than the wavelength of the electromagnetic waves, and is located inside the processing vessel. The measurement unit measures the power of transmitted waves, reflected waves, or scattered waves of the electromagnetic waves at each frequency in the resonant structure. The control unit performs a measurement process in which the power of the transmitted wave, the reflected wave, or the scattered wave is measured by the measurement unit before the plasma processing is performed, and determines a resonant frequency (for example, a resonant frequency f r ) is calculated. Therefore, according to the plasma processing apparatus of the embodiment, it is possible to stably increase the density of plasma by resonance. Furthermore, according to the plasma processing apparatus of the embodiment, it is possible to calculate the transmission characteristic value (S 21 value) or reflectance characteristic value (S 11 This reduces the processing load compared to when the resonance frequency is calculated using the frequency distribution of the

[0135] Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative in all respects and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the claims. [Explanation of symbols]

[0136] 1. Plasma processing equipment 10. Device body 11 Control device 12 Processing container 14 Stages 14a Base 14b Edge Ring 14c Electrostatic Chuck 16 Microwave output device 18 Antenna 20 Dielectric window 20a Bottom side 20b Top surface 21 Waveguide 22 Measuring instruments 22a directional coupler 22b waveguide 22c filter 22d Attenuator 23 Antenna 26 Tuner 27 Mode Converter 28 coaxial waveguide 30 slot plate 32 Dielectric plate 34 Cooling jacket 38 Gas Supply Section 100 resonant structure 101 Resonator 101A 1st resonator 101B 2nd resonator 101C 3rd resonator 111A~111C Ring members 112A~112C Dielectric plate S Processing space WP board

Claims

1. a processing vessel providing a processing space in which plasma processing is performed; an electromagnetic wave generator that generates electromagnetic waves to be supplied to the processing space; a resonant structure located within the processing vessel, the resonant structure including an array of a plurality of resonators that can resonate with a magnetic field component of the electromagnetic wave and have a size smaller than the wavelength of the electromagnetic wave; a measuring unit that measures, for each frequency, the power of the electromagnetic wave traveling from the electromagnetic wave generator to the resonant structure and the power of the transmitted wave, reflected wave, or scattered wave of the electromagnetic wave at the resonant structure; Control unit and Equipped with The control unit a measurement process of measuring the power of the electromagnetic wave and the power of the transmitted wave, the reflected wave, or the scattered wave by the measurement unit before the plasma process is performed; a calculation process of calculating a resonance frequency of the resonant structure based on a frequency distribution of a characteristic value of the resonant structure calculated from the power of the electromagnetic wave and the power of the transmitted wave, the reflected wave, or the scattered wave; A plasma processing apparatus that performs the above steps.

2. The control unit 2. The plasma processing apparatus according to claim 1, wherein during the plasma processing, the electromagnetic wave generator is controlled to generate the electromagnetic wave including a frequency component in a target frequency band higher than the resonant frequency, thereby performing a resonance processing in which the electromagnetic wave resonates with the resonant structure.

3. The control unit 2. The plasma processing apparatus according to claim 1, wherein the electromagnetic wave generator is controlled to generate an electromagnetic wave having a lower power than the electromagnetic wave generated during the plasma processing so that plasma is not generated in the processing space, and the measurement processing is performed in a state where no plasma is generated in the processing space.

4. The control unit 4. The plasma processing apparatus according to claim 3, wherein the electromagnetic wave generator is controlled to generate an electromagnetic wave having a lower power than the electromagnetic wave generated during the plasma processing, the electromagnetic wave including a single frequency component, and the measurement processing is performed while sweeping the frequency of the single frequency component of the electromagnetic wave.

5. The control unit 4. The plasma processing apparatus according to claim 3, wherein the electromagnetic wave generator is controlled to generate an electromagnetic wave having a lower power than the electromagnetic wave generated during the plasma processing, the electromagnetic wave including a plurality of frequency components belonging to a predetermined frequency bandwidth, and the measurement processing is performed for each frequency of the plurality of frequency components of the electromagnetic wave.

6. The control unit 2. The plasma processing apparatus according to claim 1, wherein, before performing the measurement process, the electromagnetic wave generator is controlled to generate electromagnetic waves having a power equal to or greater than that of the electromagnetic waves generated during the plasma process, thereby generating plasma in the processing space, and performing a heating process in which the generated plasma is used to heat the resonant structure.

7. a waveguide for guiding the electromagnetic waves generated by the electromagnetic wave generator to the processing space side; The plasma processing apparatus according to claim 1 , wherein the measurement unit measures the power of the electromagnetic wave propagating through the waveguide and the power of the reflected wave propagating through the waveguide for each frequency.

8. The resonant structure comprises: The plasma processing apparatus according to claim 1 , wherein the plasma processing apparatus is disposed along a first surface of a member provided so as to face the processing space.

9. a dielectric body having a first surface facing the processing space; an electromagnetic wave supply unit that supplies the electromagnetic wave to the processing space via the dielectric; Equipped with The resonant structure comprises: The plasma processing apparatus of claim 8 , which is disposed along the first surface of the dielectric.

10. a processing vessel providing a processing space in which plasma processing is performed; an electromagnetic wave generator that generates electromagnetic waves to be supplied to the processing space; a resonant structure located within the processing vessel, the resonant structure including an array of a plurality of resonators that can resonate with a magnetic field component of the electromagnetic wave and have a size smaller than the wavelength of the electromagnetic wave; a measuring unit that measures the power of a transmitted wave, a reflected wave, or a scattered wave of the electromagnetic wave in the resonant structure for each frequency; Control unit and Equipped with The control unit a measurement process of measuring the power of the transmitted wave, the reflected wave, or the scattered wave by the measurement unit before the plasma processing is performed; a calculation process for calculating a resonant frequency of the resonant structure based on a frequency distribution of the power of the transmitted wave, the reflected wave, or the scattered wave; A plasma processing apparatus that performs the above steps.

11. a processing vessel providing a processing space in which plasma processing is performed; an electromagnetic wave generator that generates electromagnetic waves to be supplied to the processing space; a resonant structure located within the processing vessel, the resonant structure including an array of a plurality of resonators that can resonate with a magnetic field component of the electromagnetic wave and have a size smaller than the wavelength of the electromagnetic wave; a measuring unit that measures the power of the transmitted wave, the reflected wave, or the scattered wave of the electromagnetic wave in the resonant structure for each frequency; A method for measuring a resonant frequency of a resonant structure in a plasma processing apparatus comprising: measuring the power of the electromagnetic wave and the power of the transmitted wave, the reflected wave, or the scattered wave for each frequency by the measuring unit before performing the plasma processing; calculating a resonant frequency of the resonant structure based on a frequency distribution of a characteristic value of the resonant structure calculated from the power of the electromagnetic wave and the power of the transmitted wave, the reflected wave, or the scattered wave; A method for measuring a resonant frequency, comprising:

12. 12. The resonant frequency measuring method according to claim 11, further comprising the step of controlling the electromagnetic wave generator during the plasma processing to generate the electromagnetic wave including a frequency component in a target frequency band higher than the resonant frequency, thereby resonating the electromagnetic wave with the resonant structure.

13. a processing vessel providing a processing space in which plasma processing is performed; an electromagnetic wave generator that generates electromagnetic waves to be supplied to the processing space; a resonant structure located within the processing vessel, the resonant structure including an array of a plurality of resonators that can resonate with a magnetic field component of the electromagnetic wave and have a size smaller than the wavelength of the electromagnetic wave; a measuring unit that measures the power of the transmitted wave, the reflected wave, or the scattered wave of the electromagnetic wave in the resonant structure for each frequency; A method for measuring a resonant frequency of a resonant structure in a plasma processing apparatus comprising: measuring the power of the transmitted wave, the reflected wave, or the scattered wave for each frequency by the measuring unit before performing the plasma processing; calculating a resonant frequency of the resonant structure based on the frequency distribution of the power of the transmitted wave, the reflected wave, or the scattered wave; A method for measuring a resonant frequency, comprising:

14. 14. The resonant frequency measuring method according to claim 13, further comprising the step of controlling the electromagnetic wave generator during the plasma processing to generate the electromagnetic wave including a frequency component in a target frequency band higher than the resonant frequency, thereby resonating the electromagnetic wave with the resonant structure.

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