Plasma processing device and plasma measuring method

Abstract

This plasma processing device comprises: a processing container that provides a processing space; an electromagnetic wave generator that is configured so as to supply electromagnetic waves and generate plasma in the processing space; a first dielectric body that is provided such that a first surface thereof faces the processing space; an electromagnetic wave supply unit that is configured so as to supply electromagnetic waves to the processing space via the first dielectric body; and a resonator array structure that is positioned along the first surface of the first dielectric body in the processing container. The resonator array structure includes a plurality of resonators that can resonate with a magnetic field component of the electromagnetic waves and have a size smaller than the wavelength of the electromagnetic waves. The plurality of resonators have a structure in which C-shaped ring members that are constituted by conductors are stacked on one surface of a dielectric plate. At least one of the C-shaped ring members also serves as a probe for measuring plasma information.

Description

Plasma processing apparatus and plasma measurement method

[0001] The present disclosure relates to a plasma processing apparatus and a plasma measurement method.

[0002] The plasma processing apparatus disclosed in Patent Document 1 includes a processing vessel, an electromagnetic wave generator, and a resonator array. The processing vessel provides a processing space. The electromagnetic wave generator generates electromagnetic waves for plasma excitation and is supplied to the processing space. The resonator array is formed by arranging multiple resonators, each of which can resonate with the magnetic field component of the electromagnetic wave and has a size smaller than the wavelength of the electromagnetic wave, and is located within the processing vessel.

[0003] International Publication No. 2023 / 032725

[0004] The present disclosure provides a plasma processing apparatus and a plasma measurement method that can quantitatively evaluate plasma generated via a resonator array structure in the vicinity of the plasma.

[0005] A plasma processing apparatus according to one aspect of the present disclosure includes a processing vessel providing a processing space, an electromagnetic wave generator configured to supply electromagnetic waves and generate plasma in the processing space, a first dielectric body having a first surface facing the processing space, an electromagnetic wave supply unit configured to supply the electromagnetic waves to the processing space via the first dielectric body, and a resonator array structure positioned along the first surface of the first dielectric body within the processing vessel. The resonator array structure includes a plurality of resonators capable of resonating with the magnetic field component of the electromagnetic waves and having a size smaller than the wavelength of the electromagnetic waves. The plurality of resonators have a structure in which C-shaped ring members made of conductors are stacked on one surface of a dielectric plate. At least one of the C-shaped ring members also serves as a probe for measuring plasma information.

[0006] According to the present disclosure, plasma generated via a resonator array structure can be quantitatively evaluated in its vicinity.

[0007] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus according to an embodiment of the present disclosure. FIG. 2 is a plan view showing an example of the configuration of a dielectric window and a resonator array according to the embodiment, viewed from below. FIG. 3 is a view showing an example of the configuration of a card-shaped resonator according to the embodiment. FIG. 4 is a view showing an example of the configuration of a card-shaped resonator according to the embodiment. FIG. 5 is a view showing another example of the configuration of a card-shaped resonator according to the embodiment. FIG. 6 is a view showing an example of a cross section of a card-shaped resonator according to the embodiment. FIG. 7 is a view showing an example of the configuration of a card-shaped resonator that also serves as a probe according to the embodiment. FIG. 8 is a view showing an example of a cross section of a card-shaped resonator that also serves as a probe according to the embodiment. FIG. 9 is a view showing an example of the relationship between the S21 value of a card-shaped resonator and the frequency of a microwave. FIG. 10 is a perspective view showing an example of a resonator array according to the embodiment. FIG. 11 is a plan view showing an example of an arrangement of cells in the resonator array according to the embodiment, viewed from below. FIG. 12 is a perspective view showing an example of a base plate according to the embodiment. FIG. 13 is a cross-sectional view showing an example of the B-B cross section of FIG. 11. Fig. 14 is a cross-sectional view showing an example of the A-A cross section in Fig. 10. Fig. 15 is a diagram showing an example of a combination of a probe and plasma in a cell space. Fig. 16 is a diagram showing an example of a combination of a probe and plasma in a cell space. Fig. 17 is a diagram showing an example of an equivalent circuit for plasma measurement using an insulated probe. Fig. 18 is a diagram showing an example of a Fourier series expansion result of a measured current value. Fig. 19 is a flowchart showing an example of plasma measurement processing according to this embodiment.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a plasma processing apparatus and a plasma measurement method will be described in detail below with reference to the accompanying drawings. However, the disclosed technology is not limited to the following embodiments.

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

[0010] Here, it is known that when the power of the microwaves supplied into the processing vessel is increased and the plasma electron density reaches a certain upper limit, the dielectric constant of the space inside the processing vessel becomes negative. This upper limit of the electron density is appropriately called the "cutoff density." Furthermore, the refractive index is known as an index indicating whether microwaves propagate through space. The refractive index N is expressed by the following formula (1): N = √ε√μ (1) where ε: dielectric constant, μ: magnetic permeability

[0011] Since magnetic permeability is generally positive, when 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). As a result, microwaves are attenuated and cannot propagate through the space within the processing vessel. When the electron density of the plasma 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 being densified over a wide area.

[0012] Therefore, it is expected that it will be possible to realize high density plasma over a wide area, and that the plasma generated via the resonator array structure (hereinafter also referred to as metamaterial) will be quantitatively evaluated in its vicinity.

[0013] 1 is a schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus according to an embodiment of the present disclosure. The plasma processing apparatus 1 includes an apparatus main body 10 and a control device 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, a resonator array structure 100, and a measurement unit 220.

[0014] 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 also 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. An exhaust port 12h for exhaust is provided in the bottom 12b. The upper end of the sidewall 12a is open. The inner wall surface of the sidewall 12a faces the processing space S. That is, the sidewall 12a is provided with its inner wall surface facing the processing space S.

[0015] The sidewall 12a has an opening 12c formed therein for carrying in and out the object WP to be processed. The opening 12c is opened and closed by a gate valve G.

[0016] A dielectric window 20 is provided at the upper end of the side wall 12a, and closes 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 first 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 disposed between the dielectric window 20 and the upper end of the side wall 12a.

[0017] 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. An object to be processed WP is placed on the stage 14.

[0018] The stage 14 includes a base 14 a and an electrostatic chuck 14 c. The base 14 a is made of a conductive material such as aluminum and has a generally disk-like shape. The base 14 a is disposed in the processing chamber 12 such that the central axis of the base 14 a substantially coincides with the axis Z.

[0019] 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.

[0020] An annular baffle plate 52 having a plurality of through holes formed in the thickness direction is provided at the top of 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.

[0021] 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 workpiece WP.

[0022] 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.

[0023] An electrostatic chuck 14c is provided on the upper surface of the base 14a. The electrostatic chuck 14c attracts and holds the workpiece WP by electrostatic force. The electrostatic chuck 14c has a generally disc-shaped outer shape and includes an electrode 14d, an insulating film (dielectric film) 14e, and an insulating film (dielectric film) 14f. 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 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 attracts and holds the workpiece WP on its upper surface by electrostatic force generated by a DC voltage applied from the DC power supply 64. The upper surface of the electrostatic chuck 14c is a mounting surface on which the workpiece WP is placed, and faces the processing space S. That is, the electrostatic chuck 14c is provided with its upper surface, which is the mounting surface, facing the processing space S. An edge ring 14b is also provided on the base 14a. The edge ring 14b is disposed so as to surround the workpiece WP and the electrostatic chuck 14c. The edge ring 14b is also called a focus ring.

[0024] 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 workpiece WP on the electrostatic chuck 14c on the base 14a is controlled via the electrostatic chuck 14c on the base 14a.

[0025] The stage 14 is also 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 workpiece WP.

[0026] The microwave output device 16 outputs microwaves (an example of electromagnetic waves) for exciting the process gas supplied into the process chamber 12. The microwave output device 16 is capable of adjusting the frequency, power, bandwidth, and other parameters of the microwaves. For example, the microwave output device 16 can generate a single-frequency microwave by setting the microwave bandwidth to approximately zero. The microwave output device 16 can also generate microwaves containing multiple frequency components within a predetermined frequency bandwidth (hereinafter referred to as "broadband 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 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 microwave frequency or the central frequency of the broadband microwave, for example, within a range of 2.3 GHz to 2.5 GHz, and can adjust the bandwidth of the broadband microwave, for example, within a range of 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 broadband microwave within a range of, for example, 0 to 25 kHz.

[0027] The device main body 10 also includes a waveguide 21, a tuner 26, a mode converter 27, and a coaxial waveguide 28. The output portion of the microwave output device 16 is connected to one end of the waveguide 21. The other end of the waveguide 21 is connected to the mode converter 27. The waveguide 21 is, for example, a rectangular waveguide. The waveguide 21 is provided with a tuner 26. The tuner 26 has movable plates 26a and 26b. By adjusting the amount of protrusion of each of the movable plates 26a and 26b with respect to the internal space of the waveguide 21, it is possible to match the impedance of the microwave output device 16 with the impedance of the load.

[0028] 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.

[0029] The antenna 18 supplies microwaves to the processing space S. 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 disk-like shape from 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 a plurality of slot holes formed therein. The plurality of slot holes, for example, constitute a plurality of slot pairs. Each of the plurality of slot pairs includes two slot-shaped slot holes extending in directions intersecting each other. The plurality of slot pairs are arranged along one or more concentric circles around the central axis of the slot plate 30. Furthermore, a through-hole 30d is formed in the center of the slot plate 30, through which a conduit 36 ​​(described later) can pass.

[0030] 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.

[0031] 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 an opening formed in the center of the cooling jacket 34 and the dielectric plate 32.

[0032] 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 in the slot plate 30 via the dielectric window 20 .

[0033] The resonator array 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 .

[0034] By positioning the resonator array 100 within the processing vessel 12, microwaves supplied to the processing space S by the antenna 18 can resonate with the multiple resonators of the resonator array 100. Resonance between the microwaves and the multiple resonators allows microwaves to be efficiently supplied to the processing space S of the processing vessel 12 and makes the magnetic permeability of the processing space S 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 microwaves to propagate in the processing space S. As a result, even if the electron density of the plasma generated in the processing space S reaches the cutoff density, microwaves can propagate beyond the skin depth of the plasma, and 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, by positioning the resonator array 100 within the processing vessel 12, high-density plasma can be achieved over a wide area.

[0035] The detailed configuration of the resonator array 100 will now be described with reference to Figures 1 and 2. Figure 2 is a plan view showing an example of the configuration of the dielectric window 20 and the resonator array 100 according to this embodiment, as viewed from below. In Figure 2, the lower surface 20a of the dielectric window 20 is shown as being disk-shaped.

[0036] As shown in FIGS. 1 and 2, the resonator array structure 100 is disposed along the lower surface 20 a of the dielectric window 20 .

[0037] The resonator array structure 100 is formed by arranging a plurality of resonators 101 in a lattice pattern. The resonators 101 can resonate with the magnetic field component of microwaves and have a size smaller than the wavelength of the microwaves. Specifically, the plurality of resonators 101 includes at least one of resonators 101A and 101B shown in FIGS. 3 and 4. At least one of the plurality of resonators 101 includes resonator 101C shown in FIG. 7. Each of the plurality of resonators 101 forms a series resonant circuit consisting of a capacitor equivalent element and a coil equivalent element. The series resonant circuit is realized by patterning a conductor on a plane.

[0038] 3 is a diagram showing an example of the configuration of a card-shaped resonator 101A according to this embodiment. The card-shaped resonator 101A shown in FIG. 3 has a structure in which two C-shaped, concentric, conductor ring members 111A 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 resonator 101A to form a series resonant circuit.

[0039] FIG. 4 is a diagram illustrating an example of the configuration of a card-shaped resonator 101B according to this embodiment. The card-shaped resonator 101B shown in FIG. 4 has a structure in which a dielectric plate 112B is disposed between two C-shaped ring members 111B made of a conductor and arranged adjacent to each other in opposite directions. That is, in the resonator 101B, the dielectric plate 112B is sandwiched between the two C-shaped ring members 111B arranged in opposite directions. Capacitor-equivalent elements are formed on the opposing surfaces of the two C-shaped ring members 111B and on both ends of each ring member 111B, and coil-equivalent elements are formed along each ring member 111B. This allows the resonator 101B to form a series resonant circuit. The card-shaped resonator 101B can also be expressed as a card-shaped configuration for each pair of two C-shaped ring members 111B.

[0040] In the resonator 101B shown in FIG. 4 , the number of ring members 111B arranged (hereinafter also referred to as the "number of stacked layers") is two, but the number of stacked ring members 111B may be greater than two. FIG. 5 is a diagram showing another example of the configuration of the card-shaped resonator 101B according to this embodiment. The resonator 101B shown in FIG. 5 has N (N≧2) C-shaped ring members 111B made of a conductor, and has a structure in which a dielectric plate 112B is disposed between adjacent ring members 111B arranged in opposite directions. Even with this structure, the resonator 101B can form a series resonant circuit.

[0041] Furthermore, an insulating coating may be formed on each of the multiple resonators 101. FIG. 6 is a diagram showing an example of a cross section of a card-shaped resonator 101B according to this embodiment. FIG. 6 shows a side cross section of the resonator 101B shown in FIG. 4. An insulating coating (an example of a second dielectric) 113 is formed on the surface of the resonator 101B. The material of the coating 113 is, for example, ceramic. The thickness of the coating 113 is, for example, in the range of 0.001 mm to 2 mm. By forming the insulating coating 113 on each of the multiple resonators 101, abnormal discharge in each of the multiple resonators 101 can be suppressed.

[0042] Furthermore, at least one of the C-shaped ring members of each of the multiple resonators 101 may also serve as a probe for measuring plasma information. Conventionally, plasma has been measured using, for example, a probe provided on the side wall of the chamber. However, in the resonator array structure 100, plasma is generated locally in each cell (described later), making it difficult to quantitatively monitor the degree to which these plasmas are being controlled. For this reason, in this embodiment, the C-shaped ring member also serves as a probe, allowing the plasma generated via the resonator array structure 100 to be quantitatively monitored in its vicinity.

[0043] FIG. 7 illustrates an example of the configuration of a card-shaped resonator 101C that also serves as a probe according to this embodiment. The resonator 101C shown 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 in opposite directions. That is, in the resonator 101C, the dielectric plate 112C is sandwiched between the two C-shaped ring members 111C arranged in opposite directions. Capacitor-equivalent elements are formed on the opposing surfaces of the two C-shaped ring members 111C and on both ends of each ring member 111C, and coil-equivalent elements are formed along each ring member 111C. This allows the resonator 101C to form a series resonant circuit. Furthermore, wiring 114C is connected to each of the two C-shaped ring members 111C. The wiring 114C extends to the end face of the resonator 101C and can be connected to wiring 122 on the base plate 120, which will be described later, at the end face. The card-shaped resonator 101C can also be expressed as a set of two C-shaped ring members 111C formed in a card shape. The resonator 101C corresponds to the resonator 101B provided with wiring 114C.

[0044] 8 is a diagram showing an example of a cross section of a card-shaped resonator 101C that also serves as a probe according to this embodiment. FIG. 8 shows a side cross section of the resonator 101C shown in FIG. 7. An insulating coating (an example of a second dielectric) 113C is formed on the surface of the resonator 101C. The material of the coating 113C is, for example, ceramic. The thickness of the coating 113C is, for example, in the range of 0.001 mm to 2 mm. Here, the thickness of the coating 113C is defined as a thickness t １ The thickness of the dielectric plate 112C is t ２ Then, in the resonator 101C, the thickness t １ <<Thickness t ２ The thicknesses of the dielectric plate 112C and the coating 113C are determined so as to satisfy the relationship: ２ is the thickness t of the coating 113C １ It is preferable that the thickness of the C-shaped ring members 111C is 100 times or more. As a result, the two C-shaped ring members 111C function as insulating probes to measure the plasma on the side of the coating 113C, to which the wiring 114C is connected. In other words, the dielectric plate 112C is sandwiched between the two C-shaped ring members 111C of the resonator 101C, and is much thicker than the coating 113C, so the impedance between the two C-shaped ring members 111C is high. In other words, the influence of the C-shaped ring member 111C as a probe function on the side of the dielectric plate 112C is reduced.

[0045] In other words, the C-shaped ring members 111C are formed on both sides of the dielectric plate 112C and are covered with the second dielectric coating 113C. The thickness of the dielectric plate 112C between the C-shaped ring members 111C formed on both sides of the dielectric plate 112C is thicker than the thickness of the second dielectric coating 113C that covers the C-shaped ring member 111C. The thickness of the dielectric plate 112C is 100 times or more the thickness of the second dielectric coating 113C.

[0046] Referring again to Figure 1, a conduit 36 ​​is provided inside the inner conductor 28b of the coaxial waveguide 28. A through-hole 30d is formed in the center of the slot plate 30, allowing the conduit 36 ​​to pass through. The conduit 36 ​​extends through the inside of the inner conductor 28b and is connected to a gas supply unit 38.

[0047] The gas supply unit 38 supplies a processing gas for processing the workpiece 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 processing gas supply source. The valve 38b controls the supply and stop of the processing 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 processing gas from the gas supply source 38a.

[0048] The apparatus main body 10 also includes an injector 41. The injector 41 supplies gas from the conduit 36 ​​to the through-hole 20h formed in the dielectric window 20. The gas supplied to the through-hole 20h in the dielectric window 20 is sprayed into the processing space S and excited by microwaves supplied from the antenna 18 to the processing space S via the dielectric window 20. This converts the processing gas into plasma in the processing space S, and the workpiece WP is processed by ions, radicals, and the like contained in the plasma.

[0049] The main body 10 also includes a measuring unit 220. The measuring unit 220 is connected to the C-shaped ring member 111C, which also serves as an insulating probe, via wiring 222 (including wirings 122 and 114C, described later). The measuring unit 220 includes a power supply unit that applies an AC voltage to the C-shaped ring member 111C, which also serves as an insulating probe, via the wiring 222, wiring 122, and wiring 114C, described later, and an ammeter that measures the current flowing through the C-shaped ring member 111C. The power supply unit is controlled to apply a low-frequency AC voltage of, for example, 100 kHz or less and a low voltage of several volts to the C-shaped ring member 111C. In other words, the AC voltage applied from the power supply unit has a frequency and voltage that do not affect the operation of the resonator array 100. The measuring unit 220 may be provided with a low-pass filter, a band-stop filter, or the like, to suppress the influence of electromagnetic waves supplied from the microwave output device 16.

[0050] The measurement unit 220 calculates the electron temperature T ｅ and electron density n ｅ The measurement unit 220 calculates the calculated electron temperature Tｅ and electron density n ｅ The measuring unit 220 outputs the measured current value to the control device 11, and the control device 11 outputs the electron temperature T ｅ and electron density n ｅ The calculated electron temperature T ｅ and electron density n ｅ can be used for feedback control to the microwave output device 16. For example, since the resonator 101 has a sensitive response to the frequency of the electromagnetic wave, the control device 11 can ｅ and electron density n ｅ That is, the microwave output device 16 is controlled to adjust the frequency of the electromagnetic waves while checking the state of the plasma.

[0051] 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.

[0052] For example, when plasma is generated in the processing space S, the control device 11 controls the microwaves supplied to the processing space S by the antenna 18 to resonate with the multiple resonators 101 in a target frequency band higher than the resonant frequencies of the multiple resonators 101. Here, the resonant frequency is, for example, a frequency at which the transmission characteristic value (e.g., S21 value) of the multiple resonators 101 becomes a minimum value.

[0053] 9 is a diagram illustrating an example of the relationship between the S21 value of a card-shaped resonator and the frequency of a microwave. When the frequency of the microwave supplied to the processing space S by the antenna 18 matches the resonant frequency fr (approximately 2.35 GHz) of the multiple resonators 101, the S21 value of the multiple resonators 101 becomes minimal, and resonance occurs between the microwave and the multiple resonators 101. The resonance between the microwave and the multiple resonators 101 is maintained even in a predetermined frequency band (e.g., approximately 0.1 GHz) higher than the resonant frequency fr of the multiple resonators 101. In the predetermined frequency band higher than the resonant frequency fr of the multiple resonators 101, the resonance between the microwave and the multiple resonators 101 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 is possible. In this embodiment, the target frequency band is set to a predetermined frequency band (e.g., approximately 0.1 GHz) higher than the resonant frequency fr of the multiple resonators 101. The target frequency band is preferably, for example, within 0.05 times the resonant frequency fr of the plurality of resonators 101. The resonant frequency fr of the card-shaped resonator 101 can be measured, for example, by a vector network analyzer in which a transmitting / receiving antenna is arranged in a direction parallel to the ring member 111B of the card-shaped resonator 101B.

[0054] Regarding the propagation of electromagnetic waves through a plurality of resonators, the relationship between the resonant frequency and the refractive index, the permittivity, and the magnetic permeability has been reported by D. R. Smith, D. C. Vier, Th. Koschny, and C. M. Soukoulis et al. in "Electromagnetic parameter retrieval from inhomogeneous metamaterials" in "PHYSICAL REVIEW E 71, 036617 (2005)," for example.

[0055] In this way, by resonating the microwave with the multiple resonators 101 in a target frequency band higher than the resonant frequency fr of the multiple resonators 101, microwave propagation beyond the skin depth of the plasma is possible even when the plasma electron density reaches the cutoff density. Therefore, the microwave power can be 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, by resonating the microwave with the multiple resonators 101 in a target frequency band higher than the resonant frequency fr of the multiple resonators 101, high-density plasma can be achieved over a wide area.

[0056] [Details of the Resonator Array] Next, the resonator array 100 will be described in detail. As shown in Fig. 2 , the resonator array 100 has card-shaped resonators 101 arranged in a lattice pattern. In the following description, the resonator array 100 may be referred to as a metamaterial 100, and the card-shaped resonators 101 may be referred to as meta-atoms 101. In the example of Fig. 2 , the meta-atoms 101 are arranged so that cells surrounded by the meta-atoms 101 form five columns in the X-axis direction and five rows in the Y-axis direction. In other words, the meta-atoms 101 are arranged in six rows and five columns, with their longitudinal directions aligned along the X-axis direction, as in arrangements X11, X12, ..., X15, ..., X61, X62, ..., X65. The meta-atoms 101 are arranged in five rows and six columns, with their longitudinal directions aligned along the Y-axis, as in Y11, Y21, ..., Y51, ..., Y16, Y26, ..., Y56. The cell lattice width and depth are equal to or larger than the outer dimensions of the C-shaped ring member of the meta-atom 101 (for example, ring member 111B).

[0057] Furthermore, a through-hole 20h is located in the cell located at the center of the metamaterial 100. When controlling the density of the plasma, the meta-atom 101D constituting the peripheral cells and the meta-atom 101E near the cell of the through-hole 20h may have different resonant frequencies fr. For example, the meta-atom 101D has a resonant frequency fr (=approximately 2.35 GHz). Also, for example, the meta-atom 101E has a resonant frequency fr (=approximately 2.25 GHz or approximately 2.55 GHz) that is a predetermined frequency (e.g., ±0.2 GHz) away from the resonant frequency fr of the meta-atom 101D.

[0058] Fig. 10 is a perspective view showing an example of a resonator array structure according to this embodiment. Note that in the explanation of Fig. 10, the metamaterial 100 is shown upside down. Also, in Fig. 10, ring members are drawn on some of the meta-atoms 101 to make the orientation of the meta-atoms 101 easier to understand, but in reality, the surfaces are covered with a dielectric (insulating film).

[0059] 10 includes a base plate 120. The base plate 120 is made of a dielectric material such as quartz or ceramics. The base plate 120 is provided with a plurality of grooves 121X in the X-axis direction and a plurality of grooves 121Y in the Y-axis direction, into which the meta-atoms 101 are fitted.

[0060] A meta atom 101 is fitted into each of the grooves 121X and 121Y. In the following description, the meta atom 101 fitted into the groove 121X may be referred to as the meta atom 101X, and the meta atom 101 fitted into the groove 121Y may be referred to as the meta atom 101Y. Furthermore, the meta atom 101X is assumed to be wider than the meta atom 101Y, and the ends of the meta atoms 101X are assumed to be in contact with each other. Each area surrounded by the meta atom 101X and the meta atom 101Y is a cell. In the example of FIG. 10, five rows and five columns of cells are formed, consisting of cells C11 to C55.

[0061] The side pressing members 123 are fixed to the base plate 120 using screws 124 so as to contact one side of the meta-atoms 101Y at locations Y11 to Y51 and Y16 to Y56 shown in Fig. 2 among the outermost meta-atoms 101. The side pressing members 123 and the screws 124 are an example of pressing members, and are made of ceramics such as alumina, which is a dielectric material.

[0062] The side pressing members 127 are fixed to the base plate 120 using screws 128 so as to contact one side of the meta-atoms 101 at locations X11 to X15 and X61 to X65 shown in FIG. 2 among the outermost meta-atoms 101. A space 127a is formed between the side pressing members 127 and the outermost meta-atoms 101X. The space 127a is provided in consideration of plasma generation. The side pressing members 127 and the screws 128 are an example of pressing members and are made of ceramics such as alumina, which is a dielectric material.

[0063] The pressing member 129 presses down the meta-atoms 101X and 101Y between the two side pressing members 127. The pressing member 129 is placed between the two side pressing members 127 so as to press down continuously on the top of the meta-atom 101Y in the longitudinal direction and also press down on the upper end of the meta-atom 101X. In other words, the pressing member 129 is placed parallel to the side pressing member 123. The pressing member 129 is made of ceramics such as alumina, which is a dielectric material.

[0064] Member 130 is disposed above side pressing member 127 in order to secure pressing member 129. An end of pressing member 129 is sandwiched between side pressing member 127 and member 130. Member 130 is fixed to side pressing member 127 with screws 131. Member 130 and screw 131 are an example of a pressing member, and are made of ceramics such as alumina, which is a dielectric material.

[0065] Next, the arrangement and wiring of the resonators (meta-atoms) 101C in cells C11 to C55 will be described using FIGS. 11 to 14. FIG. 11 is a plan view showing an example of the arrangement of cells in a resonator array structure according to this embodiment, viewed from below. As shown in FIG. 11, cells C11 to C25 and cells C41 to C55 are surrounded on all four sides by meta-atoms (resonators) 101B. In cells C31 to C35, meta-atoms (resonators) 101C are arranged in the Y-axis direction, and meta-atoms 101B are arranged in the X-axis direction. In other words, meta-atoms 101Ca to 101Cf are arranged in arrangements Y31 to Y36 in FIG. 2, respectively. Note that the meta-atoms 101B and 101C shown in FIG. 11 may be either meta-atoms 101D or 101E in FIG. 2 from the perspective of resonant frequency. Furthermore, the meta-atom 101C may be placed in cell C33 or in any cell through which either one of the circumferences C1 or C2 passes. For example, the meta-atom 101C may be placed in a combination of cell C31 and cell C33, or a combination of cell C32 and cell C33. Cells C11 to C55 define cell spaces CS11 to CS55, which are plasma generation spaces.

[0066] Fig. 12 is a perspective view showing an example of a base plate according to this embodiment. Fig. 13 is a cross-sectional view showing an example of the B-B cross section of Fig. 11. As shown in Figs. 12 and 13, in the B-B cross section of the base plate 120, conductors 122a are provided at the bottom of the grooves 121Y in which the meta-atoms 101Ca to 101Cf are disposed. Each conductor 122a is connected to a respective wiring 122. Each wiring 122 is connected to the measurement unit 220 via each connection portion 122b and each wiring 222.

[0067] FIG. 14 is a cross-sectional view showing an example of the A-A cross section of FIG. 10. Note that FIG. 14 omits components other than the base plate 120 and meta-atoms 101Ca-101Cf. Also, FIG. 14 is upside down compared to FIG. 1. FIG. 14 shows a state in which plasmas P31-P35 are generated in the cell spaces CS31-CS35 of cells C31-C35 in the A-A cross section. At this time, in the meta-atom 101Ca, information on plasma P31 is measured by one of the C-shaped ring members 111C. That is, in the meta-atom 101Ca, an AC voltage is applied from the measurement unit 220 via the wiring 222, the connection member 122b, the wiring 122, the conductor 122a, and the wiring 114C, and the current flowing through one of the C-shaped ring members 111C is measured. Note that the other C-shaped ring member 111C measures the space outside cell C31.

[0068] For meta-atom 101Cb, information on plasma P31 is measured using one C-shaped ring member 111C, and information on plasma P32 is measured using the other C-shaped ring member 111C. Similarly, for meta-atoms 101Cc-101Ce, information on plasmas P32-P34 is measured using one C-shaped ring member 111C, and information on plasmas P33-P35 is measured using the other C-shaped ring member 111C. Furthermore, for meta-atom 101Cf, like meta-atom 101Ca, information on plasma P35 is measured using one C-shaped ring member 111C. Note that the other C-shaped ring member 111C of meta-atom 101Cf measures the space outside cell C35.

[0069] [Measurement with Probes] Here, the combination of probes and plasma in the cell space will be described with reference to FIGS. 15 and 16. FIGS. 15 and 16 are diagrams showing an example of the combination of probes and plasma in the cell space. FIG. 15 shows a case where the wiring 114C of meta-atoms 101Ca to 101Cf are each independently connected to the measurement unit 220. In this case, for example, information on plasma P31 is obtained from the wiring 122C connected to the ring member 111C on the plasma P31 side of meta-atom 101Ca, and the wiring 122C connected to the ring member 111C on the plasma P31 side of meta-atom 101Cb. Since these two probes (ring members 111C) measure the same plasma P31, information on plasma P31 is obtained based on the average value of each current value. Information on plasmas P32 to P35 is similarly obtained based on the average value of each current value. Note that the information on plasmas P31 to P35 includes the electron temperature T ｅ and electron density n ｅ Examples include:

[0070] 16 shows a case where two wires 114C of meta-atoms 101Cb to 101Ce are connected by a conductor 122a to simplify the wiring, and each wire 122 is connected to the measuring unit 220. In other words, this is a case where each wire 122 described in FIGS. 12 to 14 is used. In this case, the information of plasmas P31 to P35 is calculated by the unknown quantity x １ ~x ５ and the current values ​​of the probes (ring members 111C) of the meta-atoms 101Ca to 101Cf are current values ​​Ia to If, the following simultaneous equations (2) to (7) can be expressed.

[0071] x １ =Ia...(2) (x １ +x ２ ) / 2=Ib...(3) (x ２ +x ３ ) / 2=Ic...(4) (x ３ +x ４ ) / 2=Id...(5) (x ４ +x ５ ) / 2=Ie...(6) x５ =If...(7)

[0072] At this time, for example, in the probe of the meta-atom 101Cb, the current value is calculated by the unknown quantities x of the plasmas P31 and P32 of the adjacent cells C31 and C32. １ , x ２ Therefore, the current value Ib is calculated as the sum of the unknowns x １ , x ２ The same applies to the meta-atoms 101Cc to 101Ce, so the current values ​​Ic to Ie are the average values ​​of the adjacent cells, as shown in equations (4) to (6).

[0073] That is, the C-shaped ring members 111C provided on both sides of one resonator (meta-atom) 101 serve as probes, and correspond to adjacent cells. The current value is measured as the sum of the values ​​of the adjacent cells. The electron temperature T ｅ and electron density n ｅ is calculated based on the average value calculated from the total values ​​measured by each probe in the multiple resonators 101 facing each cell.

[0074] Here, we consider the number of equations and the number of unknowns. First, if the number of equations is the same as the number of unknowns, the simultaneous equations can be solved. If the number of equations is greater than the number of unknowns (an overdetermined system), the simultaneous equations cannot be solved, so the least squares method is used to find the solution that best satisfies all equations. If the number of equations is less than the number of unknowns (an underdetermined system), the solution to the simultaneous equations is not unique, so the possible solution with the smallest distance from the origin is estimated to be the solution.

[0075] (When the number of equations is equal to the number of unknowns) For example, in FIG. 16, if the current value If of the meta atom 101Cf is not used, then equations (2) to (6) can be used, and the number of equations and the number of unknowns will be the same. If the simultaneous equations of equations (2) to (6) are expressed as Ax=b using a square matrix A as a matrix, then the following equation (8) is obtained, which can be transformed into equation (9). In addition, A in this case －１is expressed by the following equation (10). In equation (8), the current values ​​Ia to Ie are represented by a to e. That is, the unknown quantity x １ ~x ５ Therefore, information on plasmas P31 to P35 can be obtained.

[0076] x = A －１ b ... (9)

[0077] (When the number of equations is greater than the number of unknowns (overdetermined system)) For example, in FIG. 16, when all current values ​​Ia to If of meta-atoms 101Ca to 101Cf are used, equations (2) to (7) are used, so the number of equations is greater than the number of unknowns. When the simultaneous equations of equations (2) to (7) are expressed as Ax=b using a square matrix A, the following equation (11) is obtained, which can be transformed into equation (12). In addition, Ｔ A) －１ A Ｔ is called a Moore-Penrose inverse matrix, a general inverse matrix, a pseudo-inverse matrix, etc., and is expressed as the following equation (13). In equation (11), the current values ​​Ia to If are represented by a to f. Also, A in equation (12) Ｔ is the transposed matrix of A. In other words, from equations (11) to (13), the unknown x １ ~x ５ Since it is possible to calculate the above, it is possible to obtain information on plasmas P31 to P35. Note that obtaining equation (12) is mathematically equivalent to estimating the solution by the least squares method.

[0078] x ≒ (A Ｔ A) －１ A Ｔ b...(12)

[0079] (Number of equations < number of unknowns (underdetermined system)) For example, in FIG. 16, when using the current values ​​Ib to Ie of the meta-atoms 101Cb to 101Ce, the number of equations is less than the number of unknowns because equations (3) to (6) are used. When the simultaneous equations of equations (3) to (6) are expressed as Ax = b using a square matrix A, the following equation (14) is obtained, which can be transformed into equation (15). In addition, A in this case Ｔ (AA Ｔ ) －１ is called a Moore-Penrose inverse matrix, a general inverse matrix, a pseudo-inverse matrix, etc., and is expressed as the following equation (16). In equation (14), the current values ​​Ib to Ie are represented by b to e. Ｔ is the transposed matrix of A. In other words, from equations (14) to (16), the unknown x １ ~x ５ can be calculated, and information on plasmas P31 to P35 can be obtained. Note that finding equation (15) is mathematically equivalent to finding the solution with the smallest distance from the origin among all possible solutions. Furthermore, plasma information can be obtained in a similar manner even when the number of equations is even smaller. In other words, the location of meta-atom 101C, which is the plasma measurement point, is not limited to the location of each meta-atom 101 in the resonator array structure 100, and can be at any location.

[0080] x ≒ A Ｔ (AA Ｔ ) －１ b...(15)

[0081] [Electron temperature T ｅ and electron density n ｅ Next, the electron temperature T ｅ and electron density n ｅ 17 is a diagram showing an example of an equivalent circuit for plasma measurement using an insulating probe. As shown in FIG. 17, in this embodiment, an AC voltage V is applied to the plasma via a resistor R and a capacitor C. ０ In the insulating probe of this embodiment, the plasma voltage Vｐ The nonlinearity of the current I with respect to ０ Since the AC voltage V is applied, it is possible to measure the plasma even during a process in which by-products (deposits) are generated, which would otherwise interrupt the DC current. ０ is the AC voltage V ０ The current I is measured by a power supply unit of the measuring unit 220 that applies a voltage V. The current I is measured by an ammeter connected in series with the resistance R of the measuring unit 220. Here, the current I is expressed by the following equation (17). ｐ The nonlinearity of the current I with respect to the ion saturation current I is expressed by equation (18) assuming a Maxwellian distribution. Note that equation (18) is the same as that of the Langmuir probe. ｉｓ is expressed by the following equation (19), and the electron saturation current I ｅｓ is expressed by the following equation (20).

[0082] I = f (V ｐ ) ... (17)

[0083] Here, V ｆ represents the floating potential, and φ ｐ represents the plasma potential, and T ｅ represents the electron temperature in eV, and n ｅ represents the electron density, S represents the probe area, e represents the elementary charge, and M ｉ represents the mass of the ion, and m ｅ represents the mass of an electron. AC voltage V ０ The amplitude of V ０ and Equation (17) are applied to Equation (18), and the first kind of modified Bessel function is used as shown in Equation (21) below, and the current is decomposed into frequency components as shown in Equation (22) below.

[0084]

[0085] The electron density information is calculated as the coefficient of each frequency component (electron saturation current I ｅｓ), the electron density n ｅ can be eliminated from the equation, and the electron temperature T ｅ Calculate.

[0086]

[0087] The left side of equation (23) is the measured value, and the fundamental wave (1ω) current i １ω and the amplitude of the first harmonic (2ω) current i ２ω The right side of equation (23) represents the ratio of the fundamental wave (first harmonic current) to the first harmonic (second harmonic current) when the current value measured by the insulating probe is expanded using the first kind of modified Bessel function. Therefore, the electron temperature T ｅ can be calculated based on the equation (23) from the ratio of the measured values ​​and the ratio of the fundamental wave to the first harmonic calculated by Fourier series expansion.

[0088] In addition, the current i １ω The AC component of is expressed by the following equation (24).

[0089]

[0090] Calculated electron temperature T ｅ and the fundamental wave (1ω) current i １ω Based on this, the electron density n ｅ can be calculated.

[0091]

[0092] FIG. 18 shows an example of the Fourier series expansion results of measured current values. Graph 300 in FIG. 18 shows the Fourier series expansion results of current values ​​measured with an insulated probe. A current flows through the probe in contact with the plasma exponentially with respect to the voltage applied to the probe. The current value measured by applying an AC voltage includes, for example, a fundamental wave (1ω) component having a fundamental frequency, and harmonic components such as a first harmonic (2ω) whose wavelength is twice that of the fundamental wave and a second harmonic (3ω) whose wavelength is three times that of the fundamental wave. In the example of graph 300, the fundamental wave (1ω) has a peak around 31 kHz, a first harmonic (2ω) whose peak is around 62 kHz, and a second harmonic (3ω) whose peak is around 93 kHz. By expanding the measured current value into a Fourier series, the ratio of the fundamental wave (1ω) to the first harmonic (2ω) can be calculated, as shown in the above-mentioned equation (23).

[0093] That is, in this embodiment, a sine wave AC voltage is applied to the insulating probe (ring member 111C), and the waveform distorted by the plasma is detected and subjected to Fourier series expansion to obtain the electron temperature T ｅ and electron density n ｅ For example, in the example of FIG. 16, the current values ​​Ia to If measured by the probes (ring members 111C) of the meta-atoms 101Ca to 101Cf are expanded into a Fourier series, and the electron temperature T ｅ and electron density n ｅ is the unknown x １ ~x ５ are calculated as follows:

[0094] [Plasma Measurement Method] Next, an example of plasma measurement processing in the plasma processing apparatus 1 will be described. Fig. 19 is a flowchart showing an example of plasma measurement processing according to this embodiment. The plasma measurement processing shown in Fig. 19 is realized by the control device 11 controlling each part of the apparatus main body 10.

[0095] First, the workpiece WP is loaded into the processing vessel 12 and placed on the electrostatic chuck 14c. The control device 11 then 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. The control device 11 then controls the exhaust device 56 to adjust the pressure inside the processing vessel 12. Next, the control device 11 controls the microwave output device 16 to supply microwaves from the coaxial waveguide 28 to the processing space S inside the processing vessel 12. This generates plasma of the processing gas inside the processing vessel 12 (step S1). The plasma generated in the processing space S inside the processing vessel 12 performs a plasma processing process on the workpiece WP.

[0096] The control device 11 controls the measurement unit 220 to apply an AC voltage to the C-shaped ring member 111C of the meta-atom 101C, which also serves as a probe (step S2). The control device 11 controls the measurement unit 220 to measure the value of the current flowing through the probe (ring member 111C) (step S3). The control device 11 controls the measurement unit 220 to calculate the electron temperature T ｅ and electron density n ｅ (Step S4). The control device 11 calculates the electron temperature T ｅ and electron density n ｅ The control device 11 acquires the acquired electron temperature T ｅ and electron density n ｅ Based on this, for example, the microwave output device 16 is controlled to adjust the frequency of the electromagnetic waves, thereby controlling the plasma.

[0097] When the plasma processing process is completed, the processed object WP is carried out of the processing chamber 12 by a robot arm (not shown).

[0098] As described above, according to this embodiment, the plasma processing apparatus 1 includes a processing vessel 12, an electromagnetic wave generator (microwave output device 16), a first dielectric (dielectric window 20), an electromagnetic wave supply unit (antenna 18), and a resonator array 100. The processing vessel 12 provides a processing space S. The electromagnetic wave generator is configured to supply electromagnetic waves to generate plasma in the processing space. The first dielectric is provided with a first surface facing the processing space S. The electromagnetic wave supply unit is configured to supply electromagnetic waves to the processing space S via the first dielectric. The resonator array 100 is located along the first surface of the first dielectric in the processing vessel 12. The resonator array 100 also includes a plurality of resonators 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. The multiple resonators have a structure in which C-shaped conductive ring members (ring members 111A to 111C) are stacked on one surface of a dielectric plate (dielectric plates 112A to 112C). At least one of the C-shaped ring members (ring member 111C) also serves as a probe for measuring plasma information. As a result, it is possible to achieve high density plasma over a wide area, and to quantitatively evaluate the plasma generated via the resonator array structure 100 in its vicinity.

[0099] Furthermore, according to this embodiment, a power supply unit (measurement unit 220) that applies an AC voltage to the probe (ring member 111C) via wiring (wirings 222, 122, 114C) and an ammeter (measurement unit 220) that measures the value of the current flowing through the probe are further provided. As a result, even if plasma in a plasma process generates by-products (deposits), it is possible to quantitatively evaluate the plasma in the vicinity of the by-products.

[0100] Furthermore, according to this embodiment, the frequency of the AC voltage is lower than the frequency of the electromagnetic wave supplied from the electromagnetic wave generator to the processing space S. As a result, it is possible to prevent the AC voltage for measurement from affecting plasma generation in the resonator array structure 100.

[0101] Furthermore, according to this embodiment, the frequency of the AC voltage is 100 kHz or less, so that the AC voltage for measurement does not affect the plasma generation in the resonator array 100.

[0102] According to this embodiment, the resonator array 100 further includes a base plate 120 having grooves (grooves 121X and 121Y) on the surface facing the processing space S, and pressing members (side pressing members 123, 127, and pressing member 129) configured to press the multiple resonators 101, which are fitted vertically into the grooves, toward the base plate 120. Wiring 122 is provided in the grooves and connected to the probe. As a result, multiple cells (e.g., cells C11 to C55) can be formed, and a probe (ring member 111C) can be positioned to measure plasma in a specific cell (e.g., cells C31 to C35).

[0103] Furthermore, according to this embodiment, the C-shaped ring members are formed on both sides of the dielectric plate, so that each resonator 101 can form a series resonant circuit.

[0104] Furthermore, according to this embodiment, the C-shaped ring member is covered with the second dielectric (coatings 113 and 113C), which makes it possible to suppress abnormal discharge in each resonator 101.

[0105] Furthermore, according to this embodiment, the C-shaped ring members 111C are formed on both sides of the dielectric plate 112C and are covered with a second dielectric (coating 113C). The thickness of the dielectric plate 112C between the C-shaped ring members 111C formed on both sides of the dielectric plate 112C is greater than the thickness of the second dielectric covering the C-shaped ring member 111C. As a result, each of the C-shaped ring members 111C can function as an insulating probe for measuring plasma on the side of the coating 113C.

[0106] Furthermore, according to this embodiment, the thickness of the dielectric plate 112C is 100 times or more the thickness of the second dielectric, and as a result, each of the C-shaped ring members 111C can function as an insulating probe for measuring plasma on the coating 113C side.

[0107] Furthermore, according to this embodiment, the groove is provided so as to enable the formation of a plurality of cells surrounded by a plurality of resonators 101 fitted into the groove, and at least two cells (e.g., cells C31 and C33) among the plurality of cells (e.g., cells C11 to C55) are each provided with at least one resonator 101C including a C-shaped ring member 111C that also serves as a probe. As a result, based on the plasma information measured in the two cells, it is possible to estimate the plasma information in the other cells.

[0108] Furthermore, according to this embodiment, the probes are provided in a first cell (e.g., cell C31) at the center of the resonator array 100 and at least one second cell (e.g., cell C33) located on the outer periphery of the first cell among the plurality of cells. As a result, based on the plasma information measured in the first and second cells, it is possible to estimate the plasma information in the other cells.

[0109] Furthermore, according to this embodiment, the probes are provided in a first cell (e.g., cell C31) among the multiple cells, and in at least one second cell (e.g., cell C33) that is located on a straight line (e.g., line A-A in FIG. 10 ) that passes through the first cell and is horizontal to the base plate 120. As a result, based on the plasma information measured in the first cell and the second cell, it is possible to estimate plasma information in other cells located on the straight line. Furthermore, based on the plasma information in the multiple cells located on the straight line, it is possible to estimate plasma information in multiple cells at other positions.

[0110] Furthermore, according to this embodiment, the second cell is adjacent to the first cell or another second cell, and as a result, based on the plasma information measured in the first cell and the second cell, it is possible to easily estimate plasma information in other cells located on a line connecting the first cell and the second cell.

[0111] Furthermore, according to this embodiment, the C-shaped ring members 111C formed on both sides of the dielectric plate 112C also serve as probes, and are connected to the conductors 122a provided at the bottom of the grooves to establish electrical continuity between them, and the wiring 122 is connected to the conductors 122a. As a result, the wiring 122 can be simplified.

[0112] Furthermore, according to this embodiment, a plasma measurement method is a plasma measurement method in the plasma processing apparatus 1, in which electromagnetic waves are supplied into the processing vessel 12, and plasma is generated in a plurality of cells (e.g., C11 to C55) formed by a plurality of resonators 101 included in the resonator array 100 located within the processing vessel 12, the resonators 101 being capable of resonating with the magnetic field component of the electromagnetic waves and having a size smaller than the wavelength of the electromagnetic waves. Then, the plasma processing apparatus applies an AC voltage to a probe (ring member 111C) that serves as a plasma information measurement probe among at least one of the C-shaped conductive ring members (ring members 111A to 111C) included in the plurality of resonators 101, measures a current value flowing through the probe, and calculates, based on the measured current value, an electron temperature and an electron density of the plasma in the cell where the probe is located. As a result, the plasma generated via the resonator array 100 can be quantitatively evaluated in its vicinity.

[0113] Furthermore, according to this embodiment, the probes are provided in a plurality of cells, and the current value is measured for each cell, thereby making it possible to calculate plasma information for each cell.

[0114] Furthermore, according to this embodiment, the probes are C-shaped ring members 111C provided on both sides of one resonator 101, and correspond to adjacent cells, respectively, and the current value is measured as the total value of each adjacent cell, and the plasma electron temperature and electron density are calculated based on the average values ​​calculated from the total values ​​measured by each probe in the multiple resonators 101 facing each cell. As a result, it is possible to calculate plasma information for each adjacent cell while simplifying the wiring 122.

[0115] Furthermore, according to this embodiment, the number of probes is the same as the number of cells, and the plasma electron temperature and electron density are calculated using the same number of simultaneous equations as the number of probes, which allows for more accurate calculation of plasma information in the cells.

[0116] Furthermore, according to this embodiment, the number of probes is greater than the number of cells, and the plasma electron temperature and electron density are calculated using simultaneous equations in the same number as the number of probes. As a result, the plasma information of the cells can be calculated as an overdetermined system.

[0117] Furthermore, according to this embodiment, the number of probes is smaller than the number of cells, and the plasma electron temperature and electron density are calculated using simultaneous equations in the same number as the number of probes. As a result, the plasma information of the cells can be calculated as an underdetermined system.

[0118] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, and modifications may be made to the above-described embodiments without departing from the spirit and scope of the appended claims.

[0119] In the above embodiment, the resonator array 100 is described as having a plurality of resonators 101 arranged in a lattice pattern, but the present invention is not limited to this. For example, a resonator array may be formed by combining a plurality of rectangular resonators each having a plurality of resonators 101 integrated in the X-axis or Y-axis direction.

[0120] In the above embodiment, the resonator array 100 is arranged along the lower surface 20 a of the dielectric window 20, but this is not limiting. For example, the resonator array 100 may be embedded in the dielectric window 20 or arranged at a distance from the lower surface 20 a of the dielectric window 20. Furthermore, for example, the resonator array 100 may be arranged along the upper surface of the electrostatic chuck 14 c, the upper surface of which faces the processing space S, or may be arranged at a distance from the upper surface of the electrostatic chuck 14 c. Furthermore, for example, the resonator array 100 may be arranged along the inner wall surface of the sidewall 12 a of the processing vessel 12, or may be arranged at a distance from the inner wall surface of the sidewall 12 a of the processing vessel 12.

[0121] In the above-described embodiment, the output portion of the microwave output device 16 may be connected to the base 14a, which is a high-frequency electrode. In this case, the base 14a supplies the electromagnetic waves output from the microwave output device 16 to the processing space S via the electrostatic chuck 14c. In such a configuration, the resonator array 100 may be embedded in the electrostatic chuck 14c.

[0122] In the above-described embodiment, the resonator array 100 is formed by arranging a plurality of resonators 101, each of which can resonate with the magnetic field component of an electromagnetic wave and has a size smaller than the wavelength of the electromagnetic wave, in a lattice pattern along the lower surface 20 a of the dielectric window 20. However, the arrangement of the resonators 101 may be any arrangement along the lower surface 20 a of the dielectric window 20. For example, the resonators 101 may be arranged at predetermined intervals along one direction. Furthermore, for example, the resonator array may be formed in a flat plate shape, and the resonators 101 may be arranged in a lattice pattern along a plane parallel to the lower surface 20 a of the dielectric window 20. In other words, when viewed from the lower surface 20 a, a C-shaped ring member, which is shown transparently, may be arranged in a lattice pattern so that the C shape is visible. In this case, the magnetic field generated by the antenna is directed in a direction that penetrates the C-shaped ring member.

[0123] Furthermore, in the above-described embodiment, an inductively coupled coil is used as the antenna for injecting electromagnetic waves, but the present invention is not limited to this as long as it can generate a magnetic field in a direction penetrating the ring members 111A to 111C of the multiple resonators 101 of the resonator array structure 100. The antenna for injecting such electromagnetic waves is not limited to an inductively coupled coil, and any antenna or mechanism for injecting electromagnetic waves, such as a slot antenna, a monopole antenna, a capacitively coupled electrode, or a magnetron, can be used.

[0124] In the above embodiment, microwaves are used as the electromagnetic waves for plasma excitation supplied to the processing space S. However, the present invention is not limited to this. For example, electromagnetic waves in the very high frequency (VHF) to ultra high frequency (UHF) bands may be supplied to the processing space S as the electromagnetic waves for plasma excitation.

[0125] The present disclosure may also be configured as follows: (1) A plasma processing apparatus comprising: a processing vessel providing a processing space; an electromagnetic wave generator configured to supply electromagnetic waves to generate plasma in the processing space; a first dielectric body having a first surface facing the processing space; an electromagnetic wave supply unit configured to supply the electromagnetic waves to the processing space via the first dielectric body; and a resonator array located along the first surface of the first dielectric body in the processing vessel, wherein the resonator array includes a plurality of resonators that can resonate with a magnetic field component of the electromagnetic waves and have a size smaller than the wavelength of the electromagnetic waves, the plurality of resonators having a structure in which C-shaped ring members made of conductors are stacked on one surface of a dielectric plate, and at least one of the C-shaped ring members also serves as a probe for measuring information about the plasma. (2) The plasma processing apparatus according to (1), further comprising: a power supply unit that applies an AC voltage to the probe via wiring; and an ammeter that measures a value of a current flowing through the probe. (3) The plasma processing apparatus according to (2), wherein the frequency of the AC voltage is lower than the frequency of the electromagnetic waves supplied from the electromagnetic wave generator to the processing space. (4) The plasma processing apparatus according to (3), wherein the frequency of the AC voltage is 100 kHz or less. (5) The plasma processing apparatus according to (2) or (3), wherein the resonator array structure further includes: a base plate having grooves on a surface facing the processing space; and a pressing member configured to press the plurality of resonators fitted vertically into the grooves toward the base plate, and the wiring is provided in the groove and connected to the probe. (6) The plasma processing apparatus according to any one of (1) to (5), wherein the C-shaped ring members are formed on both sides of the dielectric plate. (7) The plasma processing apparatus according to any one of (1) to (6), wherein the C-shaped ring member is covered with a second dielectric.(8) The plasma processing apparatus according to (6), wherein the C-shaped ring members are formed on both sides of the dielectric plate and are covered with a second dielectric, and the thickness of the dielectric plate between the C-shaped ring members formed on both sides of the dielectric plate is thicker than the thickness of the second dielectric covering the C-shaped ring members. (9) The plasma processing apparatus according to (8), wherein the thickness of the dielectric plate is 100 times or more the thickness of the second dielectric. (10) The plasma processing apparatus according to (5), wherein the groove is formed so that a plurality of cells surrounded by the plurality of resonators fitted in the groove can be formed, and at least two of the plurality of cells are each provided with at least one resonator including the C-shaped ring member that also serves as the probe. (11) The plasma processing apparatus according to (10), wherein the probe is provided in a first cell at the center of the resonator array structure and at least one second cell located outer circumferentially of the first cell among the plurality of cells. (12) The plasma processing apparatus according to (11), wherein the probe is provided in the first cell and at least one second cell among the plurality of cells, the second cell being positioned on a straight line passing through the first cell and horizontal to the base plate. (13) The plasma processing apparatus according to (12), wherein the second cell is adjacent to the first cell or another second cell. (14) The plasma processing apparatus according to (5), wherein the C-shaped ring members formed on both sides of the dielectric plate also serve as the probe and are connected to conductors provided at the bottoms of the grooves to be electrically connected to each other, and the wiring is connected to the conductors.(15) A plasma measurement method for a plasma processing apparatus, wherein, in a state in which electromagnetic waves are supplied into a processing vessel of the plasma processing apparatus and plasma is generated in a plurality of cells formed by a plurality of resonators included in a resonator array structure located in the processing vessel, the resonators being capable of resonating with a magnetic field component of the electromagnetic waves and having a size smaller than the wavelength of the electromagnetic waves, the plasma measurement method is performed by the plasma processing apparatus, applying an AC voltage to a probe that measures information about the plasma, the probe being made of at least one C-shaped ring member made of a conductor included in the plurality of resonators, measuring a value of a current flowing through the probe, and calculating an electron temperature and an electron density of the plasma in the cell in which the probe is located based on the measured current value. (16) The plasma measurement method according to (15), wherein the probe is provided in a plurality of the cells, and the current value is measured for each of the cells. (17) The plasma measurement method according to (15), wherein the probes are double-ended by the C-shaped ring members provided on both sides of one of the resonators and correspond to adjacent cells, the current value is measured as a total value for each of the adjacent cells, and the electron temperature and the electron density of the plasma are calculated based on average values ​​calculated from the total values ​​measured by each of the probes in a plurality of the resonators facing each of the cells. (18) The plasma measurement method according to (17), wherein the number of the probes and the number of the cells are the same, and the electron temperature and the electron density of the plasma are calculated using simultaneous equations the same number as the number of the probes. (19) The plasma measurement method according to (17), wherein the number of the probes is greater than the number of the cells, and the electron temperature and the electron density of the plasma are calculated using simultaneous equations the same number as the number of the probes. (20) The plasma measurement method according to (17), wherein the number of the probes is less than the number of the cells, and the electron temperature and the electron density of the plasma are calculated using simultaneous equations the same in number as the number of the probes.

[0126] REFERENCE SIGNS LIST 1 Plasma processing apparatus 10 Apparatus main body 11 Control device 12 Processing container 16 Microwave output device 18 Antenna 20 Dielectric window 100 Resonator array structure (metamaterial) 101 Resonator (metaatom) 111A to 111C Ring member 112A to 112C Dielectric plate 113, 113C Coating 114C, 122, 222 Wiring 120 Base plate 121X, 121Y Groove 122a Conductor 123, 127 Side pressing member 129 Pressing member 220 Measurement unit C11 to C55 Cell S Processing space

Claims

1. A plasma processing apparatus comprising: a processing vessel for providing a processing space; an electromagnetic wave generator configured to supply electromagnetic waves to generate plasma in the processing space; a first dielectric with a first surface facing the processing space; an electromagnetic wave supply unit configured to supply the electromagnetic waves to the processing space via the first dielectric; and a resonator array structure located along the first surface of the first dielectric within the processing vessel, wherein the resonator array structure includes a plurality of resonators capable of resonating with a magnetic field component of the electromagnetic waves and having a size smaller than a wavelength of the electromagnetic waves, the plurality of resonators having a structure in which C-shaped ring members made of a conductor are stacked on one surface of a dielectric plate, and at least one of the C-shaped ring members also serves as a probe for measuring information of the plasma.

2. The plasma processing apparatus according to claim 1, further comprising: a power supply unit that applies an AC voltage to the probe via wiring; and an ammeter that measures a value of a current flowing through the probe.

3. The plasma processing apparatus according to claim 2, wherein the frequency of the AC voltage is lower than the frequency of the electromagnetic waves supplied from the electromagnetic wave generator to the processing space.

4. The plasma processing apparatus according to claim 3, wherein the frequency of the AC voltage is 100 kHz or less.

5. The plasma processing apparatus according to claim 2 or 3, wherein the resonator array structure further includes a base plate having grooves on a surface facing the processing space, and a pressing member configured to press the multiple resonators fitted vertically into the grooves against the base plate, and the wiring is provided in the grooves and connected to the probe.

6. The plasma processing apparatus according to claim 1 or 2, wherein the C-shaped ring members are formed on both sides of the dielectric plate.

7. The plasma processing apparatus according to claim 1 or 2, wherein the C-shaped ring member is covered with a second dielectric material.

8. The plasma processing apparatus described in claim 6, wherein the C-shaped ring members are formed on both sides of the dielectric plate and are covered with a second dielectric, and the thickness of the dielectric plate between the C-shaped ring members formed on both sides of the dielectric plate is thicker than the thickness of the second dielectric covering the C-shaped ring members.

9. The plasma processing apparatus according to claim 8, wherein the thickness of the dielectric plate is 100 times or more the thickness of the second dielectric.

10. The plasma processing apparatus of claim 5, wherein the groove is arranged so as to enable the formation of a plurality of cells surrounded by the plurality of resonators fitted into the groove, and at least two of the plurality of cells are each provided with at least one of the resonators including the C-shaped ring member that also serves as the probe.

11. The plasma processing apparatus according to claim 10, wherein the probe is provided in a first cell at the center of the resonator array structure and at least one second cell located on the outer periphery side of the first cell, among the plurality of cells.

12. The plasma processing apparatus according to claim 11, wherein the probe is provided in the first cell among the plurality of cells and in at least one of the second cells that passes through the first cell and is positioned on a straight line horizontal to the base plate.

13. The plasma processing apparatus according to claim 12, wherein the second cell is adjacent to the first cell or another of the second cells.

14. The plasma processing apparatus described in claim 5, wherein the C-shaped ring members formed on both sides of the dielectric plate also serve as the probe and are connected to a conductor provided at the bottom of the groove so as to be conductive to each other, and the wiring is connected to the conductor.

15. A plasma measurement method in a plasma processing apparatus, comprising: a) supplying an electromagnetic wave into a processing vessel of the plasma processing apparatus; and b) generating plasma in a plurality of cells formed of a plurality of resonators, the plurality of resonators being included in a resonator array structure located in the processing vessel and capable of resonating with a magnetic field component of the electromagnetic wave and having a size smaller than the wavelength of the electromagnetic wave; c) applying an AC voltage to a probe for measuring information of the plasma, the probe being formed by at least one of C-shaped ring members made of a conductor included in the plurality of resonators; d) measuring a current value flowing through the probe; and e) calculating, based on the measured current value, an electron temperature and an electron density of the plasma in the cell in which the probe is located.

16. The plasma measurement method according to claim 15, wherein the probe is provided in a plurality of the cells, and the current value is measured for each of the cells.

17. The plasma measurement method described in claim 15, wherein the probes are C-shaped ring members provided on both sides of one of the resonators and correspond to adjacent cells, respectively, the current value is measured as a total value for each of the adjacent cells, and the electron temperature and electron density of the plasma are calculated based on average values ​​calculated from the total values ​​measured by each of the probes in a plurality of the resonators facing each of the cells.

18. The plasma measurement method according to claim 17, wherein the number of the probes and the number of the cells are the same, and the electron temperature and the electron density of the plasma are calculated using simultaneous equations the same in number as the number of the probes.

19. The plasma measurement method according to claim 17, wherein the number of the probes is greater than the number of the cells, and the electron temperature and the electron density of the plasma are calculated using simultaneous equations the same number as the number of the probes.

20. The plasma measurement method according to claim 17, wherein the number of the probes is less than the number of the cells, and the electron temperature and the electron density of the plasma are calculated using simultaneous equations the same number as the number of the probes.

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