Components for plasma treatment devices and their manufacturing methods

Abstract

A coating (53) is formed on a substrate (52) of a component for a plasma processing apparatus using a suspension plasma spraying method. The suspension (63) used in the suspension plasma spraying comprises: a fluorinated solvent (62); a plurality of yttrium fluoride particles; and a plurality of yttrium oxyfluoride particles.

Description

Component for Plasma Processing Apparatus and Method for Manufacturing the Same The present invention relates to a component for a plasma processing apparatus and a method for manufacturing the same, and more particularly, to a component disposed in a processing chamber of a plasma processing apparatus and exposed to plasma, and a method for manufacturing the same. In the manufacture of semiconductor components such as electronic components or magnetic memories, plasma etching is used for microfabrication. The inner wall of the processing chamber of a plasma processing apparatus for plasma etching is exposed to high-frequency plasma and etching gas during the etching process. Therefore, the inner wall surface of the processing chamber is protected by forming a coating having excellent plasma resistance. As prior art regarding materials for such coatings having plasma resistance, the following techniques are known. Japanese Patent Application Laid-Open No. 2004-197181 (Patent Document 1) describes a coating covering the surface of a ground portion disposed inside a plasma etching apparatus, the coating containing a Group IIIA element and a fluorine element. The coating contains a Group IIIA fluoride phase, which is orthorhombic and contains a crystal phase belonging to the space group Pnma in an amount of 50% or more. Japanese Patent Application Laid-Open No. 2009-176787 (Patent Document 2) describes a coating disposed on the surface of a ground portion inside a plasma etching apparatus, the coating being composed of one or more materials selected from the group consisting of Al 2 O 3 、YAG、Y 2 O 3 、Gd 2 O 3 、Yb 2 O 3 、YF 3 Japanese Patent Application Laid-Open No. 2016-539250 (Patent Document 3) describes a material for a coating disposed on the surface of a ground portion inside a plasma etching apparatus, the material containing Y 3 Al 5 O 12 、Y 4 Al 2 O 9 、Er 2O 3 , Gd 2 O 3 , Y 2 O 3 , Er 3 Al 5 O 12 , Gd 3 Al 5 O 12 , YF 3 、Nd 2 O 3 Any one or Y 4 Al 2 O 9 and Y 2 O 3 -ZrO 2 solid solution. Japanese Patent Application Laid-Open No. 2013-140950 (Patent Document 4) describes that a coating material on the surface of a ground portion of a plasma etching device includes yttrium fluoride and yttrium oxyfluoride. Japanese Patent Publication No. 2014-141390 (Patent Document 5), Japanese Patent Publication No. 2016-27624 (Patent Document 6), and Japanese Patent Publication No. 2018-82154 (Patent Document 7) describe that the material of the coating on the surface of the ground portion disposed inside the plasma etching device is yttrium oxide, yttrium fluoride, and yttrium oxyfluoride with an average crystallite size of less than 100 nm, and the coating is formed by using an aerosol deposition method. It is known that the aerosol deposition method is characterized in that the surface unevenness of the formed coating can be reduced compared to the atmospheric plasma thermal spray method. On the other hand, Kazuhiro Ueda et al. disclosed in the X-ray Analysis Research Committee (Editor) of the Japanese Society for Analytical Chemistry, on pages 197-205 of X-ray Analysis Progress 50 (April 1, 2019) (Non-Patent Document 1), that more foreign substances are generated when the average crystallite size is increased. Japanese Patent Application Laid-Open No. 2019-192701 (Patent Document 8) discloses that by setting the crystallite size of the coating film on the grounding part disposed inside the plasma processing apparatus to 50 nm or less, the generation of foreign substances on the semiconductor wafer subjected to internal processing can be reduced. In addition, it is disclosed that by controlling the temperature of the substrate of the grounding part within a predetermined range when forming the coating film, the low-temperature phase ratio can be made 60% or more, and the crystallite size can be made 50 nm or less. In Japanese Patent Application Laid-Open No. 2017-190475 (Patent Document 9), as a thermal spray material capable of obtaining a yttrium-based fluoride thermal spray coating, a specific range of the mixing ratio of yttrium fluoride granulated powder and yttrium oxide granulated powder is disclosed. The yttrium-based fluoride thermal spray coating has sufficient corrosion resistance to plasma and can effectively prevent damage to the substrate caused by acid penetration even during the pickling process. Japanese Patent Application Laid-Open No. 2017-150085 (Patent Document 10) describes a manufacturing process of a thermal spray coating formed of yttrium fluoride capable of suppressing particle generation. This process uses a high-speed flame spraying method or an atmospheric pressure plasma spraying method to supply a slurry of yttrium fluoride particles having an average particle diameter within a specific range at a position downstream of the nozzle far from the thermal spray gun or at the tip position of the nozzle. Japanese Patent Application Laid-Open No. 2020-172702 (Patent Document 11) describes a method for forming a thermal spray coating on components or members in a plasma etching apparatus. It discloses a method of forming a thermal spray coating by thermal spraying a slurry in which rare earth / aluminum monoclinic system (R 4 Al 2 O 9 ) is dispersed in a solvent, and forming the thermal spray coating by a suspension plasma spraying method. Suspension plasma spraying is also referred to as SPS (Suspension Plasma Spraying), suspension plasma spraying, or suspension liquid plasma spraying. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-197181 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-176787 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-539250 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-140950 [Patent Document 5] Japanese Patent Application Laid-Open No. 2014-141390 [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-27624 [Patent Document 7] Japanese Patent Application Laid-Open No. 2018-82154 [Patent Document 8] Japanese Patent Application Laid-Open No. 2019-192701 [Patent Document 9] Japanese Patent Application Laid-Open No. 2017-190475 [Patent Document 10] Japanese Patent Application Laid-Open No. 2017-150085 [Patent Document 11] Japanese Patent Application Laid-Open No. 2020-172702 [Non-Patent Document] [Non-Patent Document 1] Kazuhiro Ueda, Kazuyuki Ikenaga, Tomoyuki Tamura, Masahiro Kadoya, "Research on the Crystal Structure and Foreign Substance Generation Mechanism of Yttrium-Based Materials for Plasma Etching Devices", The Chemical Society of Japan, X-Ray Analysis Research Committee (Editor), Advances in X-Ray Analysis 50, Agne Technical Center, Publication Date: April 1, 2019, pp. 197-205. [Problems to be Solved by the Invention] However, the inventors' research has found that the above-mentioned prior art using atmospheric plasma spraying has problems due to the following points not being fully considered. In other words, even for the purpose of reducing the crystal size of the formed coating film, when pulverizing the raw material used to form the coating film, due to the friction between the conveying gas such as dry nitrogen and the raw material powder, the raw material powder becomes charged and agglomerates, and the pulverizing effect of the raw material cannot be fully obtained. In addition, even if a conveying gas containing moisture is used to reduce the charging of the raw material powder, the raw material powder will also agglomerate due to the adsorption force of the moisture on the surface of the raw material powder, resulting in the inability to fully obtain the pulverizing effect of the raw material. Furthermore, due to the influence of the agglomeration of the raw material powder, a part of the raw material powder is not completely melted and is deposited in a semi-molten state, so it is difficult to form a thick microcrystalline layer. That is to say, in the above-mentioned prior art using atmospheric plasma spraying, the agglomeration of the above-mentioned raw materials is not fully considered. In order to prevent the agglomeration of the raw material powder, it is effective to use a suspension plasma spraying method in which the raw material is dispersed in a solvent. A method of suspending an oxide raw material in a solvent is disclosed in the suspension plasma spraying in Patent Document 11. In this suspension plasma spraying method, a suspension of raw materials dispersed in an organic solvent such as water or ethanol is used, and the solvent in the suspension acts as a thermally activated solution and reacts with the raw material powder, generating more energy than the atmospheric plasma spraying method. Therefore, in suspension plasma spraying, the raw material powder is completely melted and deposited, and thus a thicker microcrystalline layer can be formed than in the atmospheric plasma spraying method. However, the inventors' research has found that in the suspension plasma spraying method using a suspension in which raw materials are dispersed in a solvent, when fluorides or fluorides oxides are used as raw materials, the following problems occur. In other words, in the process of forming a coating film using the suspension plasma spraying method, the raw material powder composed of fluoride or fluoride oxide thermally decomposes and reacts with oxygen generated in the solvent or oxygen in the atmosphere to form an oxide. As a result, yttrium oxide is mixed into the formed coating film. When such a coating film is used in a plasma etching device, when the coating film is exposed to the fluorine plasma used in the etching process, a part of the yttrium oxide in the coating film reacts with the fluorine plasma and changes to a fluoride. At this time, the volume of the yttrium oxide part expands, resulting in cracks on the surface of the coating film. As a result, fine particles fly off from the coating film as foreign substances. If the scattered fine particles adhere to an object to be processed such as a semiconductor wafer as foreign substances, the object to be processed cannot be normally plasma-processed. As a result, the yield of the plasma processing of the object to be processed decreases. In the above prior art, sufficient consideration has not been given to the conditions for forming a sprayed coating film that can sufficiently suppress the generation of the above-mentioned fine particles. The main object of the present application is to reduce foreign substances generated from the members used in the plasma processing device. Other objects and novel features will become apparent from the description and drawings of this specification. [Means for Solving the Problem] A summary of the representative embodiments disclosed in the present application is briefly described as follows. A method for manufacturing a member for a plasma processing device according to an embodiment forms a coating on a substrate of the member for the plasma processing device using a suspension plasma spraying method. The suspension used in the suspension plasma spraying contains: a solvent containing fluorine; a plurality of yttrium fluoride particles; and a plurality of yttrium fluoride oxide particles. [Advantageous Effects of the Invention] According to one embodiment, foreign substances generated from the surface of the coating film of the member disposed in the processing chamber of the plasma processing device can be reduced, and the life of the coating film can be extended. Hereinafter, the embodiments will be described in detail with reference to the drawings. In addition, in all the drawings used to illustrate the embodiments, components having the same function are given the same reference numerals, and their repeated description will be omitted. And, in the following embodiments, unless particularly necessary, the description of the same or similar parts will not be repeated in principle. (Embodiment 1) <Configuration of Plasma Processing Apparatus> Hereinafter, the plasma processing apparatus 1 of the present embodiment will be described with reference to FIG. 1. FIG. 1 is a longitudinal sectional view showing a schematic configuration of the plasma processing apparatus 1 of the present embodiment. As shown in FIG. 1, the plasma processing apparatus 1 includes a vacuum chamber 2. The processing chamber 3 is the internal space of the vacuum chamber 2. The processing chamber 3 is surrounded by the inner wall of the vacuum chamber 2. The upper part of the processing chamber 3 is a space surrounded by a cylindrical inner wall, and constitutes a discharge chamber (plasma generation chamber) for forming the plasma 4. Below the discharge chamber for forming the plasma 4 and within the processing chamber 3, a stage 5 as a sample stage is disposed. A wafer 6 as a workpiece is disposed and held on the upper surface of the stage 5. The stage 5 is a cylindrical member. The central axis of the stage 5 and the central axis of the discharge chamber are disposed coaxially or at positions that can be regarded as approximately coaxial. An exhaust port 7 is formed at the bottom of the vacuum chamber 2. The upper surface of the bottom of the vacuum chamber 2 constitutes the bottom surface of the processing chamber 3. The exhaust port 7 is disposed below the stage 5. The central axis in the vertical direction of the exhaust port 7 and the central axis in the vertical direction of the stage 5 are disposed coaxially or at positions that can be regarded as approximately coaxial. A space 8 is disposed between the bottom surface of the processing chamber 3 where the exhaust port 7 is formed and the lower surface of the stage 5. This space 8 constitutes the lower part of the processing chamber 3. In the vertical direction of the processing chamber 3, the stage 5 is held at an intermediate position between the upper end surface and the lower end surface of the processing chamber 3. An annular exhaust plate 9 is disposed in the processing chamber 3 so as to surround the stage 5. A plurality of through holes (not shown) are formed in the exhaust plate 9. The plurality of through holes communicate the space above the exhaust plate 9 in the processing chamber 3 with the space 8 below the exhaust plate 9. The space 8 below the stage 5 communicates with the discharge chamber through the plurality of through holes in the exhaust plate 9 and the gap between the side wall of the stage 5 and the cylindrical inner wall of the processing chamber 3. During the processing of the wafer 6 on the stage 5, the products generated on the upper surface of the wafer 6 and in the discharge chamber, as well as the plasma and gas particles in the discharge chamber, pass through the space 8 and are discharged to the outside of the processing chamber 3 through the exhaust port 7. Therefore, the space 8 constitutes an exhaust path. Although the detailed configuration of the mounting stage 5 is not shown in the drawings, the mounting stage 5 has: a base material, which is a cylindrical metal member; a dielectric film, which is arranged to cover the upper surface of the base material; a heater arranged inside the dielectric film; and a refrigerant flow path arranged inside the base material. Inside the mounting stage 5, the refrigerant flow paths are arranged in multiple layers concentrically or spirally around the central axis of the mounting stage 5. In addition, when the wafer 6 is arranged on the upper surface of the dielectric film of the mounting stage 5, a gas with thermal conductivity such as helium (He) gas is supplied into the gap between the lower surface of the wafer 6 and the upper surface of the dielectric film. Therefore, pipes for the flow of the gas with thermal conductivity are arranged inside the base material and the dielectric film in the mounting stage 5. The high-frequency power supply 11 is connected to the base material of the mounting stage 5 via the impedance matcher 12 and a coaxial cable. When the wafer 6 is processed using the plasma 4, the high-frequency power supply 11 supplies high-frequency power to the base material of the mounting stage 5. This high-frequency power forms an electric field above the upper surface of the wafer 6 to attract charged particles in the plasma 4. In addition, in the mounting stage 5, an electrode for electrostatic adsorption is arranged above the heater in the dielectric film on the base material. By supplying DC power to this electrode, an electrostatic force is generated inside the dielectric film and the wafer 6 to adsorb and hold the wafer 6 on the upper surface of the dielectric film. A window member 13 is arranged above the upper surface of the mounting stage 5 facing the mounting stage 5. The window member 13 is formed of a dielectric material such as quartz or ceramic and has a disk shape. The window member 13 forms the upper part of the vacuum chamber 2 and hermetically seals the processing chamber 3. In addition, a shower plate 14 is arranged below the window member 13 at a position forming the top surface of the processing chamber 3. The shower plate 14 is formed of a dielectric material such as quartz and has a disk shape. A plurality of through holes 15 are formed in the central part of the shower plate 14. The shower plate 14 is arranged such that a gap (space) 16 is formed between the lower surface of the window member 13 and the shower plate 14. The window member 13 or the shower plate 14 forms the top of the processing chamber 3. The processing gas supply pipe 17 is connected to the vacuum chamber 2 in a manner communicating with the gap 16. A valve 18 for opening / closing the inside of the processing gas supply pipe 17 is arranged at a specified position on the processing gas supply pipe 17. The processing gas to be supplied into the processing chamber 3 (processing gas) flows into the gap 16 through the processing gas supply pipe 17 opened by the valve 18, then diffuses in the gap 16, and is supplied into the processing chamber 3 through the plurality of through holes 15 of the shower plate 14. Therefore, the processing gas is supplied into the processing chamber 3 from above. The flow rate or velocity of the processing gas is adjusted by a gas flow control unit (not shown) connected to one end side of the processing gas supply pipe 17. A vacuum exhaust unit is disposed below the vacuum chamber 2, and the vacuum exhaust unit is configured to exhaust gas or particles in the processing chamber 3 via the exhaust port 7. The vacuum exhaust unit includes a pressure adjustment plate 21 and a turbo molecular pump 22 serving as a vacuum pump. The pressure adjustment plate 21 is a disk-shaped valve. The pressure adjustment plate 21 moves up and down above the exhaust port 7 to increase or decrease the flow passage area of gas flowing into the exhaust port 7. Further, in the vacuum exhaust unit, the outlet of the turbo molecular pump 22 is connected to a dry pump 23 serving as a rough vacuum pump via an exhaust pipe. A valve 24 is disposed in the exhaust pipe. The pressure adjustment plate 21 also has a function of opening / closing the valve of the exhaust port 7. A pressure detector 25 serving as a sensor is provided in the vacuum chamber 2 to detect the pressure in the processing chamber 3. A signal output from the pressure detector 25 is transmitted to a control unit (not shown) to detect the pressure value. Based on the detected pressure value and an instruction signal output from the control unit, the pressure adjustment plate 21 is driven. As a result, the position of the pressure adjustment plate 21 in the vertical direction changes, and the flow passage area of gas flowing into the exhaust port 7 increases or decreases. The dry pump 23 is connected to the vacuum chamber 2 via an exhaust pipe 27. A valve 28 and a valve 29 are connected to the exhaust pipe 27. The valve 28 is a slow exhaust valve configured to slowly exhaust the inside of the processing chamber 3 from atmospheric pressure to vacuum using the dry pump 23. The valve 29 is a main exhaust valve configured to rapidly exhaust the inside of the processing chamber 3 using the dry pump 23. A plasma forming unit is disposed above the cylindrical portion surrounding the upper part of the vacuum chamber 2 and around the side wall of the cylindrical portion. The plasma forming unit is configured to form an electric field or a magnetic field supplied to the processing chamber 3 to generate plasma 4. The plasma forming unit includes a waveguide 31, a magnetron oscillator 32, a solenoid coil 33, and a solenoid coil 34. That is, the waveguide 31 is disposed above the window member 13. A magnetron oscillator 32 that oscillates and outputs a microwave electric field is disposed at one end of the waveguide 31. The waveguide 31 is a pipe that propagates the microwave electric field output from the magnetron oscillator 32. The microwave electric field propagating in the waveguide 31 is supplied into the processing chamber 3. The waveguide 31 includes a rectangular waveguide portion 31a extending in the horizontal direction and a circular waveguide portion 31b extending in the vertical direction. The longitudinal cross section of the rectangular waveguide portion 31a has a rectangular shape. The magnetron oscillator 32 is disposed at one end of the rectangular waveguide portion 31a. The circular waveguide portion 31b is connected to the other end of the rectangular waveguide portion 31a. The cross section of the circular waveguide portion 31b has a circular shape, and the central axis extends in the vertical direction. A cylindrical cavity portion 31c that expands radially is disposed at the lower end of the circular waveguide portion 31b. An electric field of a specific mode is enhanced inside the cavity portion 31c. Multistage solenoid coils 33 and 34 serving as magnetic field generating units are disposed above and around the cavity portion 31c and around the side of the processing chamber 3. <Operation of Plasma Processing Apparatus> Next, the operation of the plasma processing apparatus 1 will be described. The wafer 6 as the object to be processed is transported inside a transfer chamber within a vacuum transfer container (not shown) connected to the side wall of the vacuum chamber 2, and is carried into the processing chamber 3 of the vacuum chamber 2 of the plasma processing apparatus 1. Specifically, the wafer 6 is placed on the front end of an arm of a vacuum transfer device (not shown) such as a robot arm disposed in the transfer chamber, transported into the processing chamber 3 of the vacuum chamber 2, and placed on the upper surface of the mounting stage 5. When the arm of the vacuum transfer device exits the processing chamber 3, the inside of the processing chamber 3 is sealed, and a DC voltage is applied to the electrostatic chuck electrodes within the dielectric film of the mounting stage 5. The electrostatic force generated thereby holds the wafer 6 on the dielectric film of the mounting stage 5. In this state, a heat-conductive gas such as He is supplied through the piping inside the mounting stage 5 to the gap between the wafer 6 and the upper surface of the dielectric film of the mounting stage 5. A coolant whose temperature has been adjusted by a coolant temperature regulator is supplied to the coolant flow path inside the mounting stage 5. As a result, heat transfer between the substrate of the mounting stage 5 whose temperature has been adjusted and the wafer 6 is promoted, and the temperature of the wafer 6 is adjusted to within a temperature range suitable for plasma processing. The processing gas whose flow rate or velocity has been adjusted by a gas flow controller is supplied into the processing chamber 3 through the processing gas supply pipe 17 and through the plurality of through holes 15 of the shower plate 14 from the gap 16. In addition, through the operation of the turbo molecular pump 22, the inside of the processing chamber 3 is evacuated from the exhaust port 7. By balancing the supply of the processing gas into the processing chamber 3 and the exhaust from the exhaust port 7, the pressure inside the processing chamber 3 is adjusted to within a pressure range suitable for plasma processing. In this state, the microwave electric field oscillated by the magnetron oscillator 32 propagates in the waveguide 31 and is radiated into the processing chamber 3 through the window member 13 and the shower plate 14. In addition, a magnetic field generated by the solenoid coils 33, 34 is supplied to the processing chamber 3, and through the interaction of this magnetic field and the microwave electric field, electron cyclotron resonance (ECR) is generated. As a result, the atoms or molecules of the processing gas are excited, ionized, and dissociated, and plasma 4 is generated inside the processing chamber 3. When generating plasma 4, high-frequency power is supplied from the high-frequency power supply 11 to the substrate on the stage 5, and a bias potential is formed above the upper surface of the wafer 6. As a result, charged particles such as ions in the plasma 4 are attracted to the upper surface of the wafer 6. On the upper surface of the wafer 6, a structure including a film to be processed and a mask layer on the film is pre-formed. Therefore, the film to be processed on the upper surface of the wafer 6 is etched. Since the film to be processed exposed from the mask layer is selectively etched, the etching of the film to be processed proceeds along the shape of the mask layer. When a detector (not shown) detects that the etching process of the film to be processed has reached the end point, the supply of high-frequency power from the high-frequency power supply 11 to the stage 5 is stopped, and the plasma 4 is extinguished. Thereby, the etching process is stopped. When the control unit determines that further etching of the wafer 6 is not required, the processing chamber 3 is evacuated to a high vacuum. In addition, the static electricity on the stage 5 is removed, and the adsorption of the wafer 6 is released. Thereafter, the arm of the vacuum transfer device enters the inside of the processing chamber 3, and after the processed wafer 6 is transferred onto the arm, as the arm contracts, the wafer 6 is carried out to the vacuum transfer chamber outside the processing chamber 3. <Ground electrode> The inner wall (inner side wall surface) of the processing chamber 3 of the plasma processing apparatus 1 is the surface facing the plasma 4 and exposed to the particles in the plasma 4. On the other hand, in order to stabilize the potential of the plasma 4 as a dielectric, a member that functions as a ground electrode facing and in contact with the plasma 4 needs to be arranged in the processing chamber 3. In the plasma processing apparatus 1 of the present embodiment, a ground electrode 41 is arranged in the processing chamber 3. The ground electrode 41 has the function of an electrode for grounding. The ground electrode 41 is an annular member. The ground electrode 41 covers a part of the surface of the inner wall of the processing chamber 3 surrounding the discharge chamber. The ground electrode 41 is arranged so as to surround the periphery (lateral periphery) of the space above the upper surface of the stage 5. At least a part of the ground electrode 41 is located at a position higher than the upper surface of the stage 5 in the vertical direction. The ground electrode 41 includes a substrate (base material) 42 made of a conductive material and a coating film 43 covering the surface of the substrate 42. In the present embodiment, the substrate 42 of the ground electrode 41 is made of a metal such as a stainless steel alloy or an aluminum alloy. The ground electrode 41 is grounded. When the plasma processing apparatus 1 operates, plasma 4 is formed in the processing chamber 3, and the ground electrode 41 is exposed to the plasma 4. Since the ground electrode 41 has the coating film 43, the coating film 43 of the ground electrode 41 is exposed in the plasma 4. In contrast to the present embodiment, if the grounding electrode 41 does not have a coating film on the surface of the base material 42, the base material 42 of the grounding electrode 41 is exposed to the plasma 4, resulting in concerns about corrosion of the base material 42 of the grounding electrode 41 and generation of foreign substances from the base material 42. As a result, there is a concern that the wafer 6 may be contaminated. Therefore, in the present embodiment, a coating film 43 made of a material with high plasma resistance is formed to cover the surface of the base material 42 of the grounding electrode 41. By forming the coating film 43 that covers the base material 42, the function of the grounding electrode 41 as an electrode can be maintained, and damage to the base material 42 of the grounding electrode 41 caused by the plasma 4 can be suppressed. As a result, corrosion of the grounding electrode 41 and the grounding electrode 41 becoming a source of foreign substances can be prevented, and contamination of the wafer 6 can be suppressed. In addition, the coating film 43 can be a laminated film. In the present embodiment, the coating film 43 of the grounding electrode 41 contains yttrium fluoride and yttrium oxyfluoride. Yttrium fluoride and yttrium oxyfluoride are excellent coating film materials with high plasma resistance. Therefore, the coating film 43 containing yttrium fluoride and yttrium oxyfluoride has high plasma tolerance. In the present embodiment, the coating film 43 of the grounding electrode 41 is formed by a suspension plasma spraying method. Compared with the atmospheric plasma spraying method, the advantage of the suspension plasma spraying method is that the raw material particles for spraying are not easily aggregated. In the present embodiment, since the coating film 43 containing yttrium fluoride and yttrium oxyfluoride is formed by the suspension plasma spraying method, the suspension used when forming the coating film 43 contains yttrium fluoride particles and yttrium oxyfluoride particles. However, according to the inventor's study, it was found that when a suspension containing yttrium fluoride particles and yttrium oxyfluoride particles is used and the coating film is formed by the suspension plasma spraying method, yttrium oxide is likely to be mixed into the formed coating film. When the proportion of yttrium oxide becomes large in the coating film containing yttrium fluoride, yttrium oxyfluoride, and yttrium oxide, foreign substances are likely to be generated from the coating film when the coating film is exposed to the plasma in the processing chamber of the plasma processing apparatus. Therefore, it is preferable to suppress the proportion of yttrium oxide in the coating film. Therefore, in the present embodiment, a fluorine-containing solvent is used as the solvent of the suspension used when forming the coating film 43. That is, when the coating film 43 is formed by the suspension plasma spraying method, a suspension containing a fluorine-containing solvent, yttrium fluoride particles, and yttrium oxyfluoride particles is used. Thereby, the mixing of yttrium oxide into the coating film 43 can be suppressed, and the content ratio of yttrium oxide in the coating film 43 can be suppressed. This will be described in more detail later. On the other hand, for the substrate 44 of the vacuum chamber 2 that does not have a grounding function, components made of metals such as stainless steel alloys or aluminum alloys are also used. The surface of the substrate 44 of the vacuum chamber 2 is also subjected to treatments such as passivation treatment, thermal spraying, PVD, and CVD to improve the plasma corrosion resistance and reduce wear. Thereby, corrosion, metal contamination, and generation of foreign substances caused by the exposure of the substrate 44 of the vacuum chamber 2 to the plasma 4 can be suppressed. In addition, a cylindrical cover member (not shown) made of ceramics such as yttrium oxide or quartz can be disposed inside the inner wall surface of the cylindrical substrate 44 and between the discharge chamber and the substrate 44. By disposing such a cover member between the substrate 44 and the plasma 4, contact between highly reactive particles in the plasma 4 and the substrate 44 can be blocked, collisions between the substrate 44 and charged particles can be shielded or reduced, and consumption of the substrate 44 can be suppressed. <Formation method of the coating film> Hereinafter, the formation method of the coating film of the present embodiment will be described with reference to FIG. 2. FIG. 2 is an explanatory diagram of the formation method of the coating film of the present embodiment. Prepare the grounding electrode 41 in a state where the coating film 43 is not formed. At this stage, since the coating film 43 is not formed on the surface of the substrate 42 of the grounding electrode 41, the surface of the substrate 42 of the grounding electrode 41 is exposed. Next, in order to improve the adhesion between the surface of the substrate 42 of the grounding electrode 41 and the coating film 43 formed thereon, the surface of the substrate 42 is roughened using a sandblasting method. The surface roughness Ra of the substrate 42 is preferably 1 μm or more (Ra ≥ 1 μm). Next, the surface of the substrate 42 of the grounding electrode 41 contaminated by the sandblasting method is subjected to a degreasing and cleaning treatment. The degreasing and cleaning treatment can be performed by ultrasonic cleaning using an organic solvent such as acetone. The surface of the substrate 42 of the grounding electrode 41 that has been subjected to the degreasing and cleaning treatment becomes the surface of the substrate 52 shown in FIG. 2. That is, the substrate 52 shown in FIG. 2 corresponds to the substrate 42 of the grounding electrode 41. Next, a process of forming the coating film 53 on the surface of the substrate 52 using a suspension plasma spraying method is performed. This process will be described below. In addition, the coating film 53 corresponds to the coating film 43 of the grounding electrode 41 described above. Put the spraying material (material for spraying) 61 and the solvent (dispersion solvent) 62 into a stirrer (not shown) and stir to prepare a suspension (liquid suspension) 63 in which the spraying material 61 is dispersed in the solvent 62. The thermal spraying material 61 used in this embodiment includes a plurality of yttrium fluoride particles and a plurality of yttrium oxyfluoride particles. Here, the thermal spraying material 61 composed of a plurality of yttrium fluoride particles and a plurality of yttrium oxyfluoride particles is used. The thermal spraying material 61 preferably does not contain yttrium oxide particles. The solvent 62 is a solvent (dispersion solvent) that disperses the thermal spraying material 61. The particles constituting the thermal spraying material 61 are dispersed in the solvent 62. The solvent 62 used in this embodiment contains fluorine. Here, a fluorocarbon liquid formed by CFC (Chlorofluorocarbon) is used as the solvent 62. Therefore, the suspension 63 used in this embodiment is a suspension containing a fluorine-containing solvent, a plurality of yttrium fluoride particles, and a plurality of yttrium oxyfluoride particles. The average crystallite size of the yttrium fluoride particles and the average crystallite size of the yttrium oxyfluoride particles constituting the thermal spraying material 61 are preferably 50 nm or less respectively. In addition, the average particle diameter of the yttrium fluoride particles and the average particle diameter of the yttrium oxyfluoride particles constituting the thermal spraying material 61 are preferably 0.05 μm or more respectively. When the average particle diameter is less than 0.05 μm, the particles are charged due to the friction between the solvent and the particles, and the particles aggregate in the suspension 63. In addition, the average particle diameter of the yttrium fluoride particles and the average particle diameter of the yttrium oxyfluoride particles constituting the thermal spraying material 61 are preferably 50 μm or less respectively. If the average particle diameter is greater than 50 μm, the particles will precipitate in the solvent, and the suspension 63 will no longer function sufficiently as a suitable suspension. In addition, the total content ratio of the yttrium fluoride particles and the yttrium oxyfluoride particles in the suspension 63 is preferably 10% by weight or more and 70% by weight or less. A high voltage 72 is applied to the nozzle 71 of the thermal spraying device, and the plasma gas 73 is caused to flow through the nozzle 71 to generate an arc discharge, thereby generating a thermal spraying flame (plasma jet) 74. The plasma gas 73 is a gas used to generate plasma, and for example, argon alone, nitrogen alone, or a mixed gas of two or more selected from argon, hydrogen, helium, and nitrogen can be used, and there is no particular limitation. The thermal spraying flame 74 is a jet of the gas that has been plasmaized and ejected from the nozzle 71. The suspension 63 prepared as described above is introduced into the suspension supply pipe 75, passed through the suspension supply pipe 75, and introduced into the thermal spraying flame 74. The suspension 63 introduced into the thermal spraying flame 74 is heated by the thermal spraying flame 74. As a result, the solvent 62 contained in the suspension 63 evaporates, and the thermal spraying material 61 contained in the suspension 63, that is, the yttrium fluoride particles and the yttrium oxyfluoride particles, become molten. At this time, a part of the yttrium fluoride and a part of the yttrium oxyfluoride are thermally decomposed to become yttrium ions, fluoride ions, and oxygen ions. Then, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine, yttrium fluoride, yttrium oxyfluoride, and yttrium oxide are formed and sprayed onto the substrate 52. In the prior art suspension plasma spraying method, an organic solvent such as water (H 2 O) or ethanol (C 2 H 5 OH) is used as the solvent for preparing the suspension. In this case, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine in the spraying flame, yttrium oxide is easily formed. This is because there is oxygen in the atmosphere and oxygen generated by the decomposition of the solvent (water or organic solvent), so the environment during recombination becomes an environment with a lot of oxygen. On the other hand, in the suspension plasma spraying method of the present embodiment, a fluorine-containing solvent is used as the solvent 62 contained in the suspension 63, and a fluorocarbon liquid formed from CFC is used. Therefore, in the spraying flame 74, oxygen in the atmosphere, oxygen generated from yttrium oxyfluoride, fluorine generated from yttrium fluoride, fluorine generated from yttrium oxyfluoride, and fluorine generated from the solvent (fluorocarbon liquid) exist around the molten material (molten liquid of the sprayed material 61). The electronegativity of fluorine is greater than that of oxygen. Therefore, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine in the spraying flame 74, the probability of re-forming yttrium oxyfluoride is higher than the probability of forming yttrium oxide. As a result, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine in the spraying flame 74, the probability of forming yttrium oxide can be reduced. Therefore, compared with the case of using water or an organic solvent as the solvent 62, when a fluorine-containing solvent (here CFC) is used as the solvent 62 as in the present embodiment, the formation of yttrium oxide in the spraying flame 74 can be suppressed. The molten yttrium fluoride, molten yttrium oxyfluoride, and molten yttrium oxide are sprayed and adhered to the substrate 52, and then cooled and solidified. As a result, a mixed film of yttrium fluoride crystals, yttrium oxyfluoride crystals, and yttrium oxide crystals is formed on the substrate 52. By repeating this process and laminating the mixed film, a coating film 53 with a thickness of about 100 μm, for example, can be formed. The coating film 53 is formed from a mixture of yttrium fluoride, yttrium oxyfluoride, and yttrium oxide. The proportion of the crystal phases contained in the coating film 53 formed by the suspension plasma spraying method of the present embodiment is as follows: the rectangular crystal (Rectangular crystal) YF 3 phase is 3% by weight, the hexagonal crystal YF 3 phase is 3% by weight, the rectangular crystal Y 5 O 4 F 7The phase is 56% by weight, the hexagonal Y-O-F phase is 36% by weight, and the monoclinic Y 2 O 3 phase is 2% by weight. This crystal phase ratio is determined by semi-quantitative analysis using the RIR (Reference Intensity Ratio) method of the intensity of X-ray diffraction. On the other hand, when water or an organic solvent is used as the solvent 62 and the coating film 53 is formed by the suspension plasma spraying method, the ratio of the crystal phases contained in the coating film 53 is as follows: rectangular crystal YF 3 phase is 3% by weight, hexagonal YF 3 phase is 3% by weight, rectangular crystal Y 5 O 4 F 7 phase is 41% by weight, hexagonal Y-O-F phase is 41% by weight, and monoclinic Y 2 O 3 phase is 6% by weight, cubic Y 2 O 3 phase is 5% by weight. According to the study by the inventor, in the suspension plasma spraying method using water or an organic solvent as the solvent 62, the yttrium oxide phase in the formed coating film 53 cannot be reduced to less than 5% by weight. Therefore, compared with the case of using water or an organic solvent as the solvent 62 and forming the coating film 53 by the suspension plasma spraying method, in the case of using a fluorocarbon liquid (CFC) as the solvent 62 and forming the coating film 53 by the suspension plasma spraying method as in the present embodiment, it was confirmed that the ratio of the yttrium oxide phase in the coating film 53 can be reduced. In order to suppress the generation of foreign substances from the coating film 53 when the coating film 53 is exposed to the plasma 4 in the processing chamber 3 of the plasma processing apparatus 1, the content ratio of yttrium oxide in the coating film 53 is preferably 9% by weight or less, and more preferably 5% by weight or less. Such a yttrium oxide content ratio can be achieved by the method for forming the coating film 53 of the present embodiment. In addition, in the coating film 53, a case where the content ratio of yttrium oxide is zero is also allowed, that is, a case where the coating film 53 does not contain yttrium oxide is allowed. FIG. 3 shows an SEM image of a cross-section of the coating film 53 when a fluorocarbon liquid (CFC) is used as the solvent 62 and the coating film 53 is formed on the substrate 52 by a suspension plasma spraying method in the present embodiment. In the SEM image of FIG. 3, the pure black region is the void 210. From the results of SEM-EDX analysis, it can be confirmed that the brighter (whiter) the contrast of the SEM image, the higher the oxygen concentration, and the darker (blacker), the higher the fluorine concentration. The bright region (white region) 209 is a region with a high oxygen concentration and is considered to be mainly composed of yttrium oxide. The dark region (black region) 208 is a region with a high fluorine concentration and is considered to be mainly composed of yttrium fluoride. Judging from the oxygen concentration and the fluorine concentration, the region 207 with a brightness (color) between the region 208 and the region 209 is considered to be mainly composed of yttrium oxyfluoride. In addition, according to the XRD analysis of the coating film 53, it was confirmed that the crystal grain size on the surface of the coating film 53 was 30 nm or less. Furthermore, through cross-sectional STEM observation, it was determined that in the coating film 53 of the present embodiment, a microcrystalline layer was formed in the region from the surface of the coating film 53 to a depth of 10 μm. In addition, when considered together with the results of the XRD analysis, it was estimated that the thickness of the microcrystalline layer with a crystal grain size of 30 nm or less was 10 μm or more. When the coating film 53 is exposed to the plasma 4 in the processing chamber 3 of the plasma processing apparatus 1, in order to suppress the generation of foreign substances from the coating film 53, it is preferable that the average size of the microcrystals of the yttrium fluoride phase in the coating film 53 and the average size of the microcrystals of the yttrium oxyfluoride phase in the coating film 53 are each 50 nm or less. Such an average size of the microcrystals can be achieved by the method for forming the coating film 53 of the present embodiment. FIG. 4 is an SEM image of a cross-section of the coating film 53 when the coating film 53 is formed on the substrate 52 by a suspension plasma spraying method using water or an organic solvent as the solvent 62. It can be clearly confirmed that the SEM image of FIG. 4 has more bright regions (white regions) 209 formed of yttrium oxide than the SEM image of FIG. 3. In addition, compared with the SEM image of FIG. 3, in the SEM image of FIG. 4, even within the intermediate color region 207, regions close to white or regions close to black are dispersed over a wider range. Therefore, compared with the case where water or an organic solvent is used as the solvent 62 and the coating film 53 is formed by a suspension plasma spraying method, in the case where a fluorocarbon liquid (CFC) is used as the solvent 62 and the coating film 53 is formed by a suspension plasma spraying method as in the present embodiment, it can be confirmed from the SEM image that the proportion of the yttrium oxide phase in the coating film 53 can be reduced. FIG. 5 is an SEM image of a cross-section of the coating film 53 when the coating film 53 is formed on the substrate 52 by an atmospheric plasma spraying method without using a suspension liquid. Compared with FIGS. 3 and 4, in the SEM image of FIG. 5, there is almost no region (white region) with a high oxygen concentration formed in the coating film 53. This implies that almost no yttrium oxide is generated. However, in the SEM image of FIG. 5, the residual particle portion 211 is also observed near the surface of the coating film 53. Here, the residual particle portion 211 is formed by stacking raw material particles in a semi-molten state. When forming the coating film 53 by the atmospheric plasma spraying method, due to the influence of raw material particle aggregation, it is difficult to set the crystal grain size near the surface of the coating film 53 to 30 nm or less. In addition, it is known that the atmospheric plasma spraying method deposits raw material particles in a semi-molten state during film formation. Since the residual particle portion 211 is heated during spraying, large crystals that grow crystallographically inside the particles are contained in the residual particle portion 211. In the atmosphere, due to air resistance, the speed of a solid is greater than that of a liquid, so the semi-molten particles reach the substrate 52 earlier than the molten raw material. As a result, the residual particle portion 211 is first deposited on the substrate 52, and the molten raw material is deposited thereon and crystallized microscopically. Therefore, the coating film 53 formed by the atmospheric plasma spraying method has a laminated structure in which a microcrystalline layer exists on its surface and a residual particle portion 211 exists inside it. When the plasma etching device is operating, due to the influence of reactions with plasma gas or ion collisions, etc., the thickness of the coating film 53 disposed inside the processing chamber gradually becomes thinner. When the microcrystalline layer on the surface of the coating film 53 disappears and the residual particle portion 211 containing large crystal grains is exposed on the surface of the coating film 53, foreign matter is generated due to the residual particle portion 211. This point in time is determined to be the end point of the life of the coating film 53. Therefore, reducing the residual particle portion 211 in the coating film 53 and increasing the thickness of the microcrystalline layer on the surface of the coating film 53 can extend the life of the coating film 53. In the present embodiment, since the coating film 53 is formed by the suspension plasma spraying method instead of the atmospheric plasma spraying method, the formation of the residual particle portion 211 in the coating film 53 can be suppressed or prevented. In addition, the microcrystalline layer on the surface of the coating film 53 can be made thicker. As a result, the life of the coating film 53 can be extended. In addition, a small amount of yttrium oxide exists near the surface of the coating film 53 in FIG. 3. This small amount of yttrium oxide may affect the generation of foreign matter, but considering the probability, there is almost no effect. The reasons are as follows. When the plasma etching device is operating, the event that foreign matter from the inner wall of the processing chamber (i.e., the source of generation) falls onto the wafer occurs when cracks appear in crystals with a larger size than the size regarded as being detected as foreign matter among the multiple crystals on the inner wall surface and fragments scatter, and the scattered fragments accidentally fall onto the wafer. Roughly estimating from the inner wall area, the microcrystalline size of the inner wall material, the number of crystals, the wafer diameter, and the inner diameter of the processing chamber, the probability of this event occurring is at 10 -12 to 10 -13 grades. In other words, in order to be able to detect the generation of foreign matter from the surface of the coating film 53, it is necessary to expose Y 2 O 3 crystals together on the surface of the coating film 53. Therefore, it is considered that the yttrium oxide observed in the SEM image of FIG. 3 has almost no influence on the generation of foreign matter. As described above, according to the present embodiment, it is possible to form the coating film 53 having a small content ratio of the yttrium oxide phase. In addition, it is possible to form the coating film 53 having a thick surface microcrystalline layer with an average microcrystal size of 30 nm or less on the surface. In the processing chamber 3 of the plasma processing apparatus 1 provided with the member (here, the ground electrode 41) having the coating film 53, it is possible to reduce the foreign matter generated from the coating film 53, and thus it is possible to extend the life of the coating film 53. In the present embodiment, CFC (chlorofluorocarbon) is used as the solvent 62. As the solvent 62, any one of FC (fluorocarbon), HCFC (hydrochlorofluorocarbon), or HFC (hydrofluorocarbon) may also be used. Alternatively, a mixed liquid of two or more of CFC, FC, HCFC, and HFC may be used as the solvent 62. Therefore, a fluorocarbon-based liquid can be used as the solvent 62. In these cases, substantially the same effect as when using CFC as the solvent 62 can also be obtained. In addition, in the present embodiment, the case where the coating film 53 and its forming method are applied to the coating film 43 of the ground electrode 41 as a member for a plasma processing apparatus has been described. The coating film 53 and its forming method of the present embodiment can also be applied to the coating film of a member for a plasma processing apparatus other than the ground electrode 41. The member for a plasma processing apparatus to which the coating film 53 and its forming method of the present embodiment are applied is disposed in the processing chamber 3 of the plasma processing apparatus 1, and when the plasma processing apparatus is in operation, the coating film of the member for a plasma processing apparatus is exposed to the plasma 4. (Embodiment 2) In the present embodiment 2, as in the above-described embodiment 1, the coating film 53 is formed by the suspension plasma spraying method, but the solvent 62 contained in the suspension 63 is different from that in the above-described embodiment 1. In the present embodiment 2, an aqueous solution of ammonium fluoride (NH 4 F) is used as the solvent 62. In addition, the common point between the above-described embodiment 1 and the present embodiment 2 is that the solvent 62 contains fluorine. Hereinafter, the process of forming the coating film 53 by the suspension plasma spraying method in the present embodiment 2 will be described with reference to FIG. 2 above. The spraying material 61 and the solvent 62 are placed in a stirrer (not shown) and stirred to prepare the suspension 63. The spraying material 61 used in the present embodiment 2 is the same as that in the above-described embodiment 1. The solvent 62 used in the second embodiment is an aqueous solution of ammonium fluoride (NH 4 F). The concentration of the ammonium fluoride aqueous solution constituting the solvent 62 is preferably 5% by weight or more and 50% by weight or less. The reason is that if the concentration of the ammonium fluoride aqueous solution is greater than 50% by weight, it is difficult to prepare a suitable suspension 63, and NH 4 F precipitates in the suspension 63 with the thermal spraying material 61 as the core. In addition, when the concentration of the ammonium fluoride aqueous solution is less than 5% by weight, the fluorine content ratio of the solvent 62 becomes low, and the effect of suppressing the ratio of yttrium oxide in the coating film 53 formed by the suspension plasma spraying method is reduced. In the second embodiment, a suspension 63 is made by using the same thermal spraying material 61 as in the first embodiment and the solvent 62 formed from an ammonium fluoride aqueous solution, and as in the first embodiment, it is introduced into the suspension supply pipe 75 and fed into the thermal spraying flame 74 through the suspension supply pipe 75. The suspension 63 fed into the thermal spraying flame 74 is heated by the thermal spraying flame 74. As a result, the solvent 62 contained in the suspension 63 evaporates, and the yttrium fluoride particles and yttrium oxyfluoride particles contained in the suspension 63 become molten. At this time, a part of the yttrium fluoride and a part of the yttrium oxyfluoride thermally decompose to become yttrium ions, fluoride ions, and oxygen ions. When the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine, yttrium fluoride, yttrium oxyfluoride, and yttrium oxide are formed and sprayed onto the substrate 52. In the suspension plasma spraying method of the second embodiment, an ammonium fluoride aqueous solution is used as the solvent 62 contained in the suspension 63. Therefore, in the thermal spraying flame 74, oxygen in the atmosphere, oxygen generated from yttrium oxyfluoride, and oxygen generated from the solvent 62 exist around the molten material (molten solution of the thermal spraying material 61). However, fluorine generated from yttrium fluoride, fluorine generated from yttrium oxyfluoride, and fluorine generated from ammonium fluoride constituting the solvent 62 also exist around the molten material. The electronegativity of fluorine is greater than that of oxygen. Therefore, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride in the thermal spraying flame 74 recombine, the probability of re-forming yttrium oxyfluoride is higher than the probability of forming yttrium oxide. As a result, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride in the thermal spraying flame 74 recombine, the probability of forming yttrium oxide can be reduced. Therefore, compared with the case of using water or an organic solvent as the solvent 62, when a fluorine-containing solvent (here, an ammonium fluoride aqueous solution) is used as the solvent 62 as in the second embodiment, the formation of yttrium oxide in the thermal spraying flame 74 can be suppressed. Molten yttrium fluoride, molten yttrium oxyfluoride, and molten yttrium oxide are sprayed and adhered to the substrate 52, and then cooled and solidified. As a result, a mixed film of yttrium fluoride crystals, yttrium oxyfluoride crystals, and yttrium oxide crystals is formed on the substrate 52. By repeating this process and laminating the mixed film, a coating film 53 having a thickness of, for example, about 100 μm is formed. The coating film 53 is formed of a mixture of yttrium fluoride, yttrium oxyfluoride, and yttrium oxide. The proportion of the crystal phase contained in the coating film 53 formed by the suspension plasma spraying method of the present Embodiment 2 is as follows: the rectangular crystal YF 3 phase is 2% by weight, the hexagonal crystal YF 3 phase is 3% by weight, the rectangular crystal Y 5 O 4 F 7 phase is 53% by weight, the hexagonal crystal Y-O-F phase is 39% by weight, and the monoclinic Y 2 O 3 phase is 3% by weight. This crystal phase ratio is determined by using the same method as in the above-described Embodiment 1. Therefore, compared with the case where water or an organic solvent is used as the solvent 62 and the coating film 53 is formed by the suspension plasma spraying method, in the case where an aqueous ammonium fluoride solution is used as the solvent 62 and the coating film 53 is formed by the suspension plasma spraying method as in the present Embodiment 2, it is confirmed that the proportion of the yttrium oxide phase in the coating film 53 can be reduced. Further, as in the present Embodiment 2, in the case where an aqueous ammonium fluoride solution is used as the solvent 62 and the coating film 53 is formed by the suspension plasma spraying method, the SEM image of the cross section of the coating film 53 is similar to the SEM image of FIG. 3 described above. That is, in the SEM image of the coating film 53 of the present Embodiment 2, it is confirmed that the amount of the above-described bright region (white region) 209 formed of yttrium oxide is significantly reduced as compared with the SEM image of FIG. 4 described above. Further, according to the XRD analysis of the coating film 53, it is also confirmed that the crystal grain size of the surface of the coating film 53 of the present Embodiment 2 is 30 nm or less. In addition, through the observation of the cross section by STEM, it can be determined that in the coating film 53 of the present Embodiment 2, a microcrystalline layer is formed in the region from the surface of the coating film 53 to a depth of 10 μm. In addition, when considered together with the XRD analysis results, it can be presumed that the thickness of the microcrystalline layer having a crystal grain size of 30 nm or less is 10 μm or more. As described in the above-described Embodiment 1, reducing the above-described residual particle portion 211 in the coating film 53 and increasing the thickness of the microcrystalline layer on the surface of the coating film 53 result in an extended life of the coating film 53. Similarly, in the present Embodiment 2, generation of the above-described residual particle portion 211 in the coating film 53 can be suppressed or prevented. In addition, the thickness of the microcrystals on the surface of the coating film 53 can be increased. As a result, the life of the coating film 53 can be extended. As described above, according to the present Embodiment 2, a coating film 53 having a low content ratio of yttrium oxide phase can be formed. In addition, a coating film 53 having a surface microcrystalline layer with an average microcrystal size of 30 nm or less in thickness on the surface can be formed. In the processing chamber 3 of the plasma processing apparatus 1 provided with a member (here, the ground electrode 41) having the coating film 53, generation of foreign matter from the surface of the coating film 53 can be reduced, and thus the life of the coating film 53 can be extended. In the present Embodiment 2, an aqueous solution of ammonium fluoride is used as the solvent 62. As the solvent 62, an aqueous solution of potassium fluoride (KF) may be used instead of the aqueous solution of ammonium fluoride. When an aqueous solution of potassium fluoride is used as the solvent 62, substantially the same effect as when an aqueous solution of ammonium fluoride is used as the solvent 62 can be obtained. When an aqueous solution of potassium fluoride is used as the solvent 62, the concentration of the aqueous solution of potassium fluoride is preferably 5% by weight or more and 50% by weight or less, similar to the concentration range of the above-described aqueous solution of ammonium fluoride. In addition, in the present Embodiment 2, an aqueous solution of sodium fluoride (NaF 2 ) can also be used as the solvent 62. When an aqueous solution concentration lower than 5% by weight is required, by using an aqueous solution of sodium fluoride (NaF 2 ) a higher effect can be obtained because the fluorine concentration in the solvent is high. However, the concentration of the aqueous solution of sodium fluoride is preferably 4% by weight or less. The reason is that if the concentration of the aqueous solution of sodium fluoride is greater than 4% by weight, sodium fluoride will precipitate in the suspension 63 with the sprayed material 61 as the nucleus. Therefore, in the present Embodiment 2, any one of an aqueous solution of ammonium fluoride, an aqueous solution of potassium fluoride, or an aqueous solution of sodium fluoride can be used as the solvent 62, or a mixed solution of two or more of an aqueous solution of ammonium fluoride, an aqueous solution of potassium fluoride, or an aqueous solution of sodium fluoride can be used. As described above, the present invention has been specifically described according to the above-described embodiments, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof. 1: Plasma processing apparatus 2: Vacuum chamber 3: Processing chamber 4: Plasma 5: Stage 6: Wafer 7: Exhaust port 8: Space 9: Exhaust plate 11: High-frequency power supply 12: Impedance matcher 13: Window member 14: Shower plate 15: Through hole 16: Gap 17: Processing gas supply pipe 18: Valve 21: Pressure adjustment plate 22: Turbomolecular pump 23: Dry pump 24: Valve 25: Pressure detector 27: Exhaust pipe 28, 29: Valve 31: Waveguide 31a: Square waveguide section 31b: Circular waveguide section 31c: Cavity section 32: Magnetron oscillator 33, 34: Solenoid coil 41: Ground electrode 42: Substrate 43: Coating film 52: Substrate 53: Coating film 61: Spraying material 62: Solvent 63: Suspension 71: Nozzle 72: High voltage 73: Plasma gas 74: Spraying flame [FIG. 1] is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus according to one embodiment. [FIG. 2] is an explanatory diagram showing a method of forming a coating film according to an embodiment. [FIG. 3] is an SEM image of a cross section of the coating film. [FIG. 4] is an SEM image of a cross section of the coating film. [FIG. 5] is an SEM image of a cross section of the coating film. 42: Substrate 43: Coating film 52: Substrate 53: Coating film 61: Spraying material 62: Solvent 63: Suspension 71: Nozzle 72: High voltage 73: Plasma gas 74: Spraying flame 75: Suspension supply pipe

Claims

1. A method for manufacturing a component for a plasma treatment device, comprising: (a) a process of preparing a substrate for use in the component for the plasma treatment device; (b) a process of preparing a first suspension comprising: a fluorinated solvent, a plurality of yttrium fluoride particles and a plurality of yttrium fluoride oxyfluoride particles; and (c) a process of forming a coating on the substrate using the aforementioned first suspension and by means of a suspension plasma spraying method.

2. A method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the solvent is a fluorocarbon liquid.

3. The method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the aforementioned solvent is formed from any one of CFC, FC, HCFC or HFC, or from a mixture of two or more of CFC, FC, HCFC and HFC.

4. The method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the aforementioned solvent is formed from any one of an aqueous solution of ammonium fluoride, an aqueous solution of potassium fluoride, or an aqueous solution of sodium fluoride, or from a mixture of two or more of an aqueous solution of ammonium fluoride, an aqueous solution of potassium fluoride, and an aqueous solution of sodium fluoride.

5. The method for manufacturing a component for a plasma treatment apparatus as claimed in claim 4, wherein the concentrations of the aforementioned ammonium fluoride aqueous solution and the aforementioned potassium fluoride aqueous solution are each 5% by weight or more and 50% by weight or less.

6. The method for manufacturing a component for a plasma treatment apparatus as claimed in claim 4, wherein the concentration of the aforementioned sodium fluoride aqueous solution is 4% by weight or less.

7. A method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the average particle size of the plurality of yttrium fluoride particles and the average particle size of the plurality of yttrium oxyfluoride particles are 0.05 μm or more and 50 μm or less, respectively.

8. A method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the aforementioned component for the plasma treatment apparatus is disposed in the treatment chamber of the plasma treatment apparatus, and the aforementioned coating is exposed to plasma during operation of the aforementioned plasma treatment apparatus.

9. A method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the yttrium oxide content in the aforementioned coating is 9% by weight or less.

10. A method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the yttrium oxide content in the aforementioned coating is 5% by weight or less.

11. A method for manufacturing a component for a plasma treatment apparatus as claimed in claim 1, wherein the aforementioned coating system comprises a yttrium fluoride phase and a yttrium oxyfluoride phase, wherein the average size of the microcrystals in the aforementioned yttrium fluoride phase and the average size of the microcrystals in the aforementioned yttrium oxyfluoride phase are respectively 50 nm or less.

Images